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Sample records for contact sensitizing chemicals
Prediction of the contact sensitizing potential of chemicals using analysis of gene expression changes in human THP-1 monocytes.
Arkusz, Joanna; Stępnik, Maciej; Sobala, Wojciech; Dastych, Jarosław
The aim of this study was to find differentially regulated genes in THP-1 monocytic cells exposed to sensitizers and nonsensitizers and to investigate if such genes could be reliable markers for an in vitro predictive method for the identification of skin sensitizing chemicals. Changes in expression of 35 genes in the THP-1 cell line following treatment with chemicals of different sensitizing potential (from nonsensitizers to extreme sensitizers) were assessed using real-time PCR. Verification of 13 candidate genes by testing a large number of chemicals (an additional 22 sensitizers and 8 nonsensitizers) revealed that prediction of contact sensitization potential was possible based on evaluation of changes in three genes: IL8, HMOX1 and PAIMP1. In total, changes in expression of these genes allowed correct detection of sensitization potential of 21 out of 27 (78%) test sensitizers. The gene expression levels inside potency groups varied and did not allow estimation of sensitization potency of test chemicals. Results of this study indicate that evaluation of changes in expression of proposed biomarkers in THP-1 cells could be a valuable model for preliminary screening of chemicals to discriminate an appreciable majority of sensitizers from nonsensitizers. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
Association between atopic dermatitis and contact sensitization
Hamann, Carsten R; Hamann, Dathan; Egeberg, Alexander
BACKGROUND: It is unclear whether patients with atopic dermatitis (AD) have an altered prevalence or risk for contact sensitization. Increased exposure to chemicals in topical products together with impaired skin barrier function suggest a higher risk, whereas the immune profile suggests a lower...... contact dermatitis is suspected....... risk. OBJECTIVE: To perform a systematic review and meta-analysis of the association between AD and contact sensitization. METHODS: The PubMed/Medline, Embase, and Cochrane databases were searched for articles that reported on contact sensitization in individuals with and without AD. RESULTS...
Multiple chemical sensitivity
Tran, Marie Thi Dao; Arendt-Nielsen, Lars; Kupers, Ron
BACKGROUND: Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by recurrent, non-specific symptoms in response to chemically unrelated exposures in non-toxic concentrations. Although the pathophysiology of MCS remains unknown, central sensitization may be an important factor...
Junge, Anne Gram
Et voksende antal mennesker i Danmark oplever at være overfølsomme over for dufte og kemikalier. Imidlertid er den tilskrevne diagnose Multiple Chemical Sensitivity (MCS) ikke medicinsk anerkendt i Danmark pga. mangel på organiske og patofysiologisk basis for symptomerne. Dette speciale bygger på...
Dantoft, Thomas Meinertz
Multiple chemical sensitivity (MCS) is a chronic disorder characterized by reports of symptoms from various organ systems attributed by the individuals to exposure to common odors and airborne chemicals in doses far below those known to induce toxic effects. There exists a general lack of knowledge......, significantly reduced levels of IL-13 in the MCS group and no group differences in the allergen specific IgE measures. The differences were independent of factors such as sex, age, Body Mass Index, asthma, smoking, depression, anxiety and allergen-specific IgE. In conclusion, the study identified a distinct...
Quantitative Risk Assessment of Contact Sensitization
Api, Anne Marie; Belsito, Donald; Bickers, David
Background: Contact hypersensitivity quantitative risk assessment (QRA) for fragrance ingredients is being used to establish new international standards for all fragrance ingredients that are potential skin sensitizers. Objective: The objective was to evaluate the retrospective clinical data...... as potential sensitizers. Methods: This article reviews clinical data for three fragrance ingredients cinnamic aldehyde, citral, and isoeugenol to assess the utility of the QRA approach for fragrance ingredients. Results: This assessment suggests that had the QRA approach been available at the time standards...
Contact sensitivity and bioavailability of chlorocresol
Andersen, Klaus Ejner; Carlsen, L; Egsgaard, Helge
Chlorocresol sensitization from 5 topical preparations was determined in guinea pigs using the cumulative contact enhancement test. Chlorocresol 5% in olive oil/acetone (4/1), and 5% in aqueous suspension stabilized with carbomer 941 were more sensitizing (55% and 60% of the animals positive......% of the chlorocresol in aqueous suspension permeated the skin in contrast to 34% and 35% of the chlorocresol in olive oil/acetone (4/1) and propylene glycol, respectively. In spite of the same amount of chlorocresol absorption from the 2 latter preparations, they showed a significant difference in sensitizing capacity...
Egsgaard, Helge; Larsen, Elfinn; Carlsen, Lars
Contact sensitivity in palmar hyperkeratotic dermatitis
Minocha Y
Full Text Available 230 patients presenting with palmar hyperkeratotic dermatitis were investigated by patch tests against various antigens depending upon occupation of the patients. Contact sensitivity was detected in 130 patients comprising of housewives (55, businessmen (20, farmers (15, teachers / clerks / students (13, doctors and nurses (9, factory workers and labourers (8, massons (7 and motor mechanics (3. Vegetables were found to be the most common agents followed by detergents and metals predominantly affecting housewives. Among the vegetables, garlic and onion were the most potent sensitizers whereas nickel was a common sensitizer among metals. Occupational factors were seen to have some influence in relation to the causative agents as indicated by higher positivity of vegetables in housewives; detergents, metals, rubber, leather, plastics in businessmen, teachers, clerks and students; fertilizers or animal foods in farmers; drugs in doctors and nurses and chromium and cobalt in massons.
Gigantic Enhancement in Sensitivity Using Schottky Contacted Nanowire Nanosensor
KAUST Repository
Wei, Te-Yu
A new single nanowire based nanosensor is demonstrated for illustrating its ultrahigh sensitivity for gas sensing. The device is composed of a single ZnO nanowire mounted on Pt electrodes with one end in Ohmic contact and the other end in Schottky contact. The Schottky contact functions as a "gate" that controls the current flowing through the entire system. By tuning the Schottky barrier height through the responsive variation of the surface chemisorbed gases and the amplification role played by the nanowire to Schottky barrier effect, an ultrahigh sensitivity of 32 000% was achieved using the Schottky contacted device operated in reverse bias mode at 275 °C for detection of 400 ppm CO, which is 4 orders of magnitude higher than that obtained using an Ohmic contact device under the same conditions. In addition, the response time and reset time have been shortened by a factor of 7. The methodology and principle illustrated in the paper present a new sensing mechanism that can be readily and extensively applied to other gas sensing systems. © 2009 American Chemical Society.
Wei, Te-Yu; Yeh, Ping-Hung; Lu, Shih-Yuan; Wang, Zhong Lin
The association between null mutations in the filaggrin gene and contact sensitization to nickel and other chemicals in the general population
Thyssen, J P; Johansen, J D; Linneberg, A
It was recently shown that filaggrin gene (FLG) null mutations are positively associated with nickel sensitization. We have hypothesized that histidine-rich filaggrin proteins in the epidermis chelate nickel ions and prevent their skin penetration and exposure to Langerhans cells. Furthermore, we...... have proposed that the low degree of genetic predisposition to nickel sensitization found by a Danish twin study was explained by a high prevalence of ear piercing among participants resulting in 'bypassing' of the filaggrin proteins....
International Journal of Biological and Chemical Sciences: Contact
International Journal of Biological and Chemical Sciences: Contact. Journal Home > About the Journal > International Journal of Biological and Chemical Sciences: Contact. Log in or Register to get access to full text downloads.
Current knowledge on biomarkers for contact sensitization and allergic contact dermatitis
Koppes, Sjors A.; Engebretsen, Kristiane A.; Agner, Tove; Angelova-Fischer, Irena; Berents, Teresa; Brandner, Johanna; Brans, Richard; Clausen, Maja-Lisa; Hummler, Edith; Jakasa, Ivone; Jurakić-Ton�ic, Ružica; John, Swen M.; Khnykin, Denis; Molin, Sonja; Holm, Jan O.; Suomela, Sari; Thierse, Hermann-Josef; Kezic, Sanja; Martin, Stefan F.; Thyssen, Jacob P.
Contact sensitization is common and affects up to 20% of the general population. The clinical manifestation of contact sensitization is allergic contact dermatitis. This is a clinical expression that is sometimes difficult to distinguish from other types of dermatitis, for example irritant and
Identification of contact and respiratory sensitizers using flow cytometry
Goutet, Michele; Pepin, Elsa; Langonne, Isabelle; Huguet, Nelly; Ban, Masarin
Identification of the chemicals responsible for respiratory and contact allergies in the industrial area is an important occupational safety issue. This study was conducted in mice to determine whether flow cytometry is an appropriate method to analyze and differentiate the specific immune responses to the respiratory sensitizer trimellitic anhydride (TMA) and to the contact sensitizer dinitrochlorobenzene (DNCB) used at concentrations with comparable immunogenic potential. Mice were exposed twice on the flanks (days 0, 5) to 10% TMA or 1% DNCB and challenged three times on the ears (days 10, 11, 12) with 2.5% TMA or 0.25% DNCB. Flow cytometry analyses were conducted on draining lymph node cells harvested on days 13 and 18. Comparing TMA and DNCB immune responses on day 13, we found obvious differences that persisted for most of them on day 18. An increased proportion of IgE+ cells correlated to total serum IgE level and an enhancement of MHC II molecule expression were observed in the lymph node B lymphocytes from TMA-treated mice. The percentage of IL-4-producing CD4+ lymphocytes and the IL-4 receptor expression were clearly higher following TMA exposure. In contrast, higher proportions of IL-2-producing cells were detected in CD4+ and CD8+ cells from DNCB-treated mice. Both chemicals induced a significant increase in the percentage of IFN-γ-producing cells among CD8+ lymphocytes but to a greater proportion following TMA treatment. In conclusion, this study encourages the use of flow cytometry to discriminate between contact and respiratory sensitizers by identifying divergent expression of immune response parameters
Perpetua U Ibekwe
Conclusions: Most ACD patients showed contact sensitization to leather products, metal, and perfume use. This knowledge is important when considering preventive measures. However, further studies are needed to provide more insight into contact allergy in Nigeria.
Contact sensitization to common haptens is associated with atopic dermatitis: new insight
Thyssen, J P; Linneberg, A; Engkilde, K
and questioned about AD Results: The variable "contact sensitization to common chemicals, but not nickel and thimerosal", was significantly associated with atopic dermatitis (OR=2.53; CI95%=1.59-4.04). The higher prevalence of contact sensitization was mainly driven by fragrance chemicals. In a sub......-analysis in non-pierced women, a positive association was also found for nickel sensitization. Nickel and thimerosal sensitization may introduce bias in data analysis since these allergies often develop following skin piercing where the skin compartments are bypassed. Discussion: We suspect that individuals...
Chemical sensitivity: pathophysiology or pathopsychology?
Genuis, Stephen J
Escalating numbers of people throughout the world are presenting to primary care physicians, allergists, and immunologists with myriad clinical symptoms after low-level exposure to assorted everyday chemicals such as smoke, perfumes, air fresheners, paints, glues, and other products. This clinical state is referred to by various diagnostic labels, including multiple chemical sensitivity disorder, environmental intolerance, chemical sensitivity (CS), and sensitivity-related illness, and has been the subject of much controversy within the health care community. The goal of this study was to provide a brief overview of the etiology, pathogenesis, clinical presentation, and management of CS. An evaluation of the medical community's response to this emerging diagnosis was also explored. This review was prepared by assessing available medical and scientific literature from MEDLINE, as well as by reviewing numerous books, toxicology journals, conference proceedings, government publications, and environmental health periodicals. A primary observation, however, is that there is limited scientific literature available on the issue of CS. The format of a traditional integrated review was chosen because such reviews play a pivotal role in scientific research and professional practice in medical issues with limited primary study and uncharted clinical territory. The sensitization state of CS seems to be initiated by a significant toxic exposure, occurring as a 1-time event, or on surpassing a threshold of toxicity after toxicant accrual from repeated lower-level exposures. Once sensitized through a toxicant-induced loss of tolerance, individuals exposed to inciting triggers such as minute amounts of diverse everyday chemicals may experience various clinical and immune sequelae, sometimes involving lymphocyte, antibody, or cytokine responses. Precautionary avoidance of inciting triggers will prevent symptoms, and desensitization immunotherapy or immune suppression may improve
Chemical kinetic functional sensitivity analysis: Elementary sensitivities
Demiralp, M.; Rabitz, H.
Sensitivity analysis is considered for kinetics problems defined in the space--time domain. This extends an earlier temporal Green's function method to handle calculations of elementary functional sensitivities deltau/sub i//deltaα/sub j/ where u/sub i/ is the ith species concentration and α/sub j/ is the jth system parameter. The system parameters include rate constants, diffusion coefficients, initial conditions, boundary conditions, or any other well-defined variables in the kinetic equations. These parameters are generally considered to be functions of position and/or time. Derivation of the governing equations for the sensitivities and the Green's funciton are presented. The physical interpretation of the Green's function and sensitivities is given along with a discussion of the relation of this work to earlier research
Current knowledge on biomarkers for contact sensitization and allergic contact dermatitis.
Koppes, Sjors A; Engebretsen, Kristiane A; Agner, Tove; Angelova-Fischer, Irena; Berents, Teresa; Brandner, Johanna; Brans, Richard; Clausen, Maja-Lisa; Hummler, Edith; Jakasa, Ivone; Jurakić-Ton�ic, Ružica; John, Swen M; Khnykin, Denis; Molin, Sonja; Holm, Jan O; Suomela, Sari; Thierse, Hermann-Josef; Kezic, Sanja; Martin, Stefan F; Thyssen, Jacob P
Contact sensitization is common and affects up to 20% of the general population. The clinical manifestation of contact sensitization is allergic contact dermatitis. This is a clinical expression that is sometimes difficult to distinguish from other types of dermatitis, for example irritant and atopic dermatitis. Several studies have examined the pathogenesis and severity of allergic contact dermatitis by measuring the absence or presence of various biomarkers. In this review, we provide a non-systematic overview of biomarkers that have been studied in allergic contact dermatitis. These include genetic variations and mutations, inflammatory mediators, alarmins, proteases, immunoproteomics, lipids, natural moisturizing factors, tight junctions, and antimicrobial peptides. We conclude that, despite the enormous amount of data, convincing specific biomarkers for allergic contact dermatitis are yet to be described. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Koppes, Sjors A.; Engebretsen, Kristiane A.; Agner, Tove
Contact sensitization is common and affects up to 20% of the general population. The clinical manifestation of contact sensitization is allergic contact dermatitis. This is a clinical expression that is sometimes difficult to distinguish from other types of dermatitis, for example irritant...... and atopic dermatitis. Several studies have examined the pathogenesis and severity of allergic contact dermatitis by measuring the absence or presence of various biomarkers. In this review, we provide a non-systematic overview of biomarkers that have been studied in allergic contact dermatitis. These include...... genetic variations and mutations, inflammatory mediators, alarmins, proteases, immunoproteomics, lipids, natural moisturizing factors, tight junctions, and antimicrobial peptides. We conclude that, despite the enormous amount of data, convincing specific biomarkers for allergic contact dermatitis are yet...
Evaluation of contact sensitivity to topical drugs in patients with contact dermatitis
Bilge Bülbül Şen
Full Text Available Background and Design: Topical drugs are an important group of contact allergens. The present study aimed to evaluate contact sensitivity to topical drugs in patients with contact dermatitis. Materials and Methods: Between 2003 and 2008, 129 patients were followed up at the Department of Dermatology at Ankara University School of Medicine with clinically suspected contact sensitivity to topical drugs. In this study, the patch test reactions to the European Standard Battery and topical drugs used by the patients and medicament patch test results were evaluated. Results: Positive patch test reaction to one or more allergens was found in 80 (62.0% of 129 patients included in the study. Sixty-one of the 80 patients (61/129, 47.3% had positive patch test reaction to medicaments. Medicament sensitivity was detected in 37.9% (49/129 of subjects. Nitrofurazone was found to be the most common allergen (18.6%. Discussion: The present study showed that topical drugs are a frequent cause of allergic contact dermatitis. Therefore, the probability of contact sensitivity to topical drugs should also be considered in patients with the clinical diagnosis of allergic contact dermatitis and, suspected cases should be evaluated further with patch testing in order to find the responsible allergens.
Migration of human antigen-presenting cells in a human skin graft onto nude mice model after contact sensitization
Hoefakker, S.; Balk, H.P.; Boersma, W.J.A.; Joost, T. van; Notten, W.R.F.; Claassen, E.
Fluorescent contact chemical allergens provoke sensitization after application on both syngeneic and allogeneic skin grafts in mice. We attempted to determine whether the functional activity in a contact sensitization response of human skin graft was affected at the level of antigen uptake and
Metals Are Important Contact Sensitizers: An Experience from Lithuania
Kotryna LinauskienÄ—
Full Text Available Background. Metals are very frequent sensitizers causing contact allergy and allergic contact dermatitis worldwide; up-to-date data based on patch test results has proved useful for the identification of a problem. Objectives. In this retrospective study prevalence of contact allergy to metals (nickel, chromium, palladium, gold, cobalt, and titanium in Lithuania is analysed. Patients/Methods. Clinical and patch test data of 546 patients patch tested in 2014–2016, in Vilnius University Hospital Santariskiu Klinikos, was analysed and compared with previously published data. Results. Almost third of tested patients (29.56% were sensitized to nickel. Younger women were more often sensitized to nickel than older ones (36% versus 22.8%, p=0.0011. Women were significantly more often sensitized to nickel than men (33% versus 6.1%, p<0.0001. Younger patients were more often sensitized to cobalt (11.6% versus 5.7%, p=0.0183. Sensitization to cobalt was related to sensitization to nickel (p<0.0001. Face dermatitis and oral discomfort were related to gold allergy (28% versus 6.9% dermatitis of other parts, p<0.0001. Older patients were patch test positive to gold(I sodium thiosulfate statistically significantly more often than younger ones (44.44% versus 21.21%, p=0.0281. Conclusions. Nickel, gold, cobalt, and chromium are leading metal sensitizers in Lithuania. Cobalt sensitization is often accompanied by sensitization to nickel. Sensitivity rate to palladium and nickel indicates possible cross-reactivity. No sensitization to titanium was found.
Airborne chemicals cause respiratory symptoms in individuals with contact allergy
Elberling, J; Linneberg, A; Mosbech, H
Exposure to fragrance chemicals causes various eye and airway symptoms. Individuals with perfume contact allergy report these symptoms more frequently than individuals with nickel allergy or no contact allergies. However, the associations between contact allergy and respiratory symptoms elicited...... by airborne chemicals other than perfumes are unclear. The study aimed to investigate the association between eye and airway symptoms elicited by airborne chemicals (other than perfumes) and contact allergy in a population-based sample. A questionnaire on respiratory symptoms was posted, in 2002, to 1189...... individuals who participated in 1997/1998 in a Danish population-based study of allergic diseases. Questions about eye and airway symptoms elicited by different airborne chemicals and airborne proteins were included in the questionnaire. Data from the questionnaire were compared with data on patch testing...
The role of glutathione S-transferase and claudin-1 gene polymorphisms in contact sensitization
Ross-Hansen, K; Linneberg, A; Johansen, J D
BACKGROUND: Contact sensitization is frequent in the general population and arises from excessive or repeated skin exposure to chemicals and metals. However, little is known about its genetic susceptibility. OBJECTIVES: To determine the role of polymorphisms of glutathione S-transferase (GST) genes...
Effect of tobacco smoking and alcohol consumption on the prevalence of nickel sensitization and contact sensitization
Thyssen, Jacob P; Johansen, Jeanne D; Menné, Torkil
There is evidence that stimulants such as alcohol and tobacco have an effect on the immune system, but little is known about how these lifestyle factors affect the prevalence of contact sensitization. This study investigated whether smoking and alcohol consumption were associated with contact...
CMS Sensitivity to Quark Contact Interactions using Dijets
Esen, Selda
We estimate CMS sensitivity to quark contact interactions in the dijet final state. The canonical model of a contact interaction among left-handed composite quarks changes the dijet angular distribution at high dijet mass. The dijet ratio variable introduced at the Tevatron is used as a simple measure of the angular distribution as a function of dijet mass. The contact interaction signal and QCD background are estimated for the dijet ratio as a function of dijet mass from 0.3 to 6.5 TeV. Statistical uncertainties are estimated for integrated luminosities of 100 pb^-1, 1 fb^-1, and 10 fb^-1 and a realistic trigger table including multiple thresholds and prescales for the single jet triggers. Systematic uncertainties on the dijet ratio are estimated and are found to be small. The chisquard between the background and the signal is estimated, including systematics, and is used to find CMS sensitivity to the contact interaction scale Lambda^+. For an integrated luminosity of 100 pb^-1, 1 fb^-1, and 10 fb^-1, CMS c...
Identifying sensitive areas on intercultural contacts: An exploratory study
Ignacio Ramos-Vidal
Full Text Available This paper analyzes the negative influence that cultural friction areas can promote on intercultural contacts. First, we expose the critical incident method like cross-cultural training model (Arthur, 2001. Then we show the negative effects that sensitive cultural zones can exert on the formation of prejudices and stereotypes about culturally diverse groups, analyzing 77 critical incidents collected in two different formative contexts. The main cultural shock areas detected are a intercultural communication barriers, b gender roles, and c the cultural expressions statement. Strategies to improve the method validity are proposed.
Contact sensitization from Compositae-containing herbal remedies and cosmetics.
Paulsen, Evy
The Compositae (Asteraceae) family of plants is currently an important cause of allergic plant contact dermatitis in Europe. The family comprises some of the oldest and most valued medicinal plants, and the increasing popularity of herbal medicine and cosmetics may theoretically result in a growing number of Compositae sensitizations from these sources. According to the literature at least 15 species, including among others arnica (Arnica montana), German and Roman chamomile (Chamomilla recutita and Chamaemelum nobile), marigold (Calendula officinalis), Echinacea and elecampane (Inula helenium), have been suspected of sensitization or elicitation of Compositae dermatitis. Epidemiological data are available for 2 species only, arnica and German chamomile, the rest of the evidence being anecdotal. Based on this, sensitization seems to occur relatively frequently with a few species such as arnica and elecampane, and occurs rarely with the majority, especially the widely used German chamomile. Sesquiterpene lactones are the most important allergens, but there are a few cases of sensitization from a coumarin, a sesquiterpene alcohol and a thiophene. The risk of elicitation of dermatitis by using Compositae-containing products in Compositae-sensitive individuals is by-and-large unknown.
Chemically sensitive interfaces on SAW devices
Ricco, A.J.; Martin, S.J. [Sandia National Labs., Albuquerque, NM (United States); Crooks, R.M.; Xu, Chuanjing [Texas A and M Univ., College Station, TX (United States); Allred, R.E. [Adherent Technologies, Inc., Albuquerque, NM (United States)
Using surface acoustic wave (SAW) devices, three approaches to the effective use of chemically sensitive interfaces that are not highly chemically selective have been examined: (1) molecular identification from time-resolved permeation transients; (2) using multifrequency SAW devices to determine the frequency dependence of analyte/film interactions; (3) use of an array of SAW devices bearing diverse chemically sensitive interfaces to produce a distinct response pattern for each analyte. In addition to their well-known sensitivity to mass changes (0.0035 monolayer of N{sub 2} can be measured), SAW devices respond to the mechanical and electronic properties of thin films, enhancing response information content but making a thorough understanding of the perturbation critical. Simultaneous measurement of changes in frequency and attenuation, which can provide the information necessary to determine the type of perturbation, are used as part of the above discrimination schemes.
Association between atopic dermatitis and contact sensitization: A systematic review and meta-analysis.
Hamann, Carsten R; Hamann, Dathan; Egeberg, Alexander; Johansen, Jeanne D; Silverberg, Jonathan; Thyssen, Jacob P
It is unclear whether patients with atopic dermatitis (AD) have an altered prevalence or risk for contact sensitization. Increased exposure to chemicals in topical products together with impaired skin barrier function suggest a higher risk, whereas the immune profile suggests a lower risk. To perform a systematic review and meta-analysis of the association between AD and contact sensitization. The PubMed/Medline, Embase, and Cochrane databases were searched for articles that reported on contact sensitization in individuals with and without AD. The literature search yielded 10,083 citations; 417 were selected based on title and abstract screening and 74 met inclusion criteria. In a pooled analysis, no significant difference in contact sensitization between AD and controls was evident (random effects model odds ratio [OR] = 0.891; 95% confidence interval [CI] = 0.771-1.03). There was a positive correlation in studies that compared AD patients with individuals from the general population (OR 1.50, 95% CI 1.23-1.93) but an inverse association when comparing with referred populations (OR 0.753, 95% CI 0.63-0.90). Included studies used different tools to diagnose AD and did not always provide information on current or past disease. Patch test allergens varied between studies. No overall relationship between AD and contact sensitization was found. We recommend that clinicians consider patch testing AD patients when allergic contact dermatitis is suspected. Copyright © 2017 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.
CONCURRENT CONTACT SENSITIZATION TO METALS IN DENTAL EXPOSURES
Maya Lyapina
Full Text Available Purpose: Sensitization to metals is a significant problem for both dental patients treated with dental materials and for dental professionals in occupational exposures. The purpose of the present study was to evaluate the incidence of concurrent contact sensitization to relevant for dental practice metals among students of dental medicine, students from dental technician school, dental professionals and patients. Material and Methods: A total of 128 participants were included in the study. All of them were patch-tested with nickel, cobalt, copper, potassium dichromate, palladium, aluminium, gold and tin. The results were subject to statistical analysis (p < 0.05. Results: For the whole studied population, potassium dichromate exhibited concomitant reactivity most often; copper and tin also often manifested co-reactivity. For the groups, exposed in dental practice, potassium dichromate and tin were outlined as the most often co-reacting metal allergens, but statistical significance concerning the co-sensitization to copper and the other metals was established only for aluminium. An increased incidence and OR for concomitant sensitization to cobalt and nickel was established in the group of dental students; to copper and nickel - in the control group; to palladium and nickel - in the group of dental professionals, the group of students of dental medicine and in the control group; to potassium dichromate and cobalt - in the group of dental students; to copper and palladium - in the control group of dental patients; to potassium dichromate and copper - in the group of dental professionals; to copper and aluminum - in the groups of students from dental technician school and of dental professionals; to copper and gold - in the groups of dental professionals and in the group of dental patients; to potassium dichromate and aluminum - in the group of dental professionals; to potassium dichromate and gold - in the group of dental professionals, and to
Predicting allergic contact dermatitis: a hierarchical structure activity relationship (SAR) approach to chemical classification using topological and quantum chemical descriptors
Basak, Subhash C.; Mills, Denise; Hawkins, Douglas M.
A hierarchical classification study was carried out based on a set of 70 chemicals—35 which produce allergic contact dermatitis (ACD) and 35 which do not. This approach was implemented using a regular ridge regression computer code, followed by conversion of regression output to binary data values. The hierarchical descriptor classes used in the modeling include topostructural (TS), topochemical (TC), and quantum chemical (QC), all of which are based solely on chemical structure. The concordance, sensitivity, and specificity are reported. The model based on the TC descriptors was found to be the best, while the TS model was extremely poor.
Sensory irritation and multiple chemical sensitivity.
Anderson, R C; Anderson, J H
Many of the symptoms described in Sick Building Syndrome (SBS) and multiple chemical sensitivity (MCS) resemble the symptoms known to be elicited by airborne irritant chemicals. Irritation of the eye, nose, and throat is common to SBS, MCS, and sensory irritation (SI). Difficulty of breathing is often seen with SBS, MCS, and pulmonary irritation (PI). We therefore asked the question: can indoor air pollutants cause SI and/or PI? In laboratory testing in which mice breathed the dilute volatile emissions of air fresheners, fabric softeners, colognes, and mattresses for 1 h, we measured various combinations of SI and PI as well as airflow decreases (analogous to asthma attacks). Air samples taken from sites associated with repeated human complaints of poor air quality also caused SI, PI, and airflow limitation (AFL) in the mice. In previous publications, we have documented numerous behavior changes in mice (which we formally studied with a functional observational battery) after exposure to product emissions or complaint site air; neurological complaints are a prominent part of SBS and MCS. All together, these data suggest that many symptoms of SBS and MCS can be described as SI, PI, AFL, and neurotoxicity. All these problems can be caused by airborne irritant chemicals such as those emitted by common commercial products and found in polluted indoor air. With some chemical mixtures (e.g., emissions of some fabric softeners, disposable diapers, and vinyl mattress covers) but not others (e.g., emissions of a solid air freshener), the SI response became larger (2- to 4-fold) when we administered a series of two or three 1-h exposures over a 24-h period. Since with each exposure the intensity of the stimulus was constant yet the magnitude of the response increased, we concluded that there was a change in the sensitivity of the mice to these chemicals. The response was not a generalized stress response because it occurred with only some mixtures of irritants and not others
Chemical control of electrical contact to sp2 carbon atoms
Frederiksen, Thomas; Foti, Giuseppe; Scheurer, Fabrice; Speisser, Virginie; Schull, Guillaume
Carbon-based nanostructures are attracting tremendous interest as components in ultrafast electronics and optoelectronics. The electrical interfaces to these structures play a crucial role for the electron transport, but the lack of control at the atomic scale can hamper device functionality and integration into operating circuitry. Here we study a prototype carbon-based molecular junction consisting of a single C60 molecule and probe how the electric current through the junction depends on the chemical nature of the foremost electrode atom in contact with the molecule. We find that the efficiency of charge injection to a C60 molecule varies substantially for the considered metallic species, and demonstrate that the relative strength of the metal-C bond can be extracted from our transport measurements. Our study further suggests that a single-C60 junction is a basic model to explore the properties of electrical contacts to meso- and macroscopic sp2 carbon structures.
Sensitive chemical neutron dosimetry using silver colloids
Brede, O.; Boes, J.; Hoesselbarth, B.
The radiation-induced formation of silver colloid was checked for its use as a sensitive dosimeter for neutron irradiation. For non-monoenergetic pulsed neutron irradiation in the Dubna IBR-30 reactor, the colloid dosimeter was found to be suitable to indicate the chemical neutron effect, i.e., to determine the sum concentration of the primary particles of water radiolysis: esub(aq)sup(-), OH and H. (author)
Identification of contact and respiratory sensitizers according to IL-4 receptor α expression and IL-2 production
Goutet, Michèle, E-mail: michele.goutet@inrs.fr; Pépin, Elsa; Langonné, Isabelle; Huguet, Nelly; Ban, Masarin
Identification of allergenic chemicals is an important occupational safety issue. While several methods exist to identify contact sensitizers, there is currently no validated model to predict the potential of chemicals to act as respiratory sensitizers. Previously, we reported that cytometry analysis of the local immune responses induced in mice dermally exposed to the respiratory sensitizer trimellitic anhydride (TMA 10%) and contact sensitizer dinitrochlorobenzene (DNCB 1%) could identify divergent expression of several immune parameters. The present study confirms, first, that IgE-positive B cells, MHC class II molecules, interleukin (IL)-2, IL-4 and IL-4Rα can differentiate the allergic reactions caused by high doses of strong respiratory (TMA, phthalic anhydride and toluene diisocyanate) and contact sensitizers (DNCB, dinitrofluorobenzene and oxazolone). The second part of the study was designed to test the robustness of these markers when classing the weakly immunogenic chemicals most often encountered. Six respiratory allergens, including TMA (2.5%), five contact allergens, including DNCB (0.25%), and two irritants were compared at doses of equivalent immunogenicity. The results indicated that IL-4Rα and IL-2 can be reliably used to discriminate sensitizers. Respiratory sensitizers induced markedly higher IL-4Rα levels than contact allergens, while irritants had no effect on this parameter. Inversely, contact allergens tended to induce higher percentages of IL-2{sup +}CD8{sup +} cells than respiratory allergens. In contrast, the markers MHC-II, IgE and IL-4 were not able to classify chemicals with low immunogenic potential. In conclusion, IL-4Rα and IL-2 have the potential to be used in classifying a variety of chemical allergens. -- Highlights: ► Identification of chemical allergens is an important occupational safety issue. ► There is currently no model to predict the potential of chemicals to induce asthma. ► We analyze immune responses induced
Goutet, Michèle; Pépin, Elsa; Langonné, Isabelle; Huguet, Nelly; Ban, Masarin
Identification of allergenic chemicals is an important occupational safety issue. While several methods exist to identify contact sensitizers, there is currently no validated model to predict the potential of chemicals to act as respiratory sensitizers. Previously, we reported that cytometry analysis of the local immune responses induced in mice dermally exposed to the respiratory sensitizer trimellitic anhydride (TMA 10%) and contact sensitizer dinitrochlorobenzene (DNCB 1%) could identify divergent expression of several immune parameters. The present study confirms, first, that IgE-positive B cells, MHC class II molecules, interleukin (IL)-2, IL-4 and IL-4Rα can differentiate the allergic reactions caused by high doses of strong respiratory (TMA, phthalic anhydride and toluene diisocyanate) and contact sensitizers (DNCB, dinitrofluorobenzene and oxazolone). The second part of the study was designed to test the robustness of these markers when classing the weakly immunogenic chemicals most often encountered. Six respiratory allergens, including TMA (2.5%), five contact allergens, including DNCB (0.25%), and two irritants were compared at doses of equivalent immunogenicity. The results indicated that IL-4Rα and IL-2 can be reliably used to discriminate sensitizers. Respiratory sensitizers induced markedly higher IL-4Rα levels than contact allergens, while irritants had no effect on this parameter. Inversely, contact allergens tended to induce higher percentages of IL-2 + CD8 + cells than respiratory allergens. In contrast, the markers MHC-II, IgE and IL-4 were not able to classify chemicals with low immunogenic potential. In conclusion, IL-4Rα and IL-2 have the potential to be used in classifying a variety of chemical allergens. -- Highlights: ► Identification of chemical allergens is an important occupational safety issue. ► There is currently no model to predict the potential of chemicals to induce asthma. ► We analyze immune responses induced in mice
An epidermal equivalent assay for identification and ranking potency of contact sensitizers
Gibbs, Susan, E-mail: S.Gibbs@VUMC.nl [Department of Dermatology, VU University Medical Centre, Dept of Oral Cell Biology, ACTA, Amsterdam (Netherlands); Corsini, Emanuela [Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano (Italy); Spiekstra, Sander W. [Department of Dermatology, VU University Medical Centre, Dept of Oral Cell Biology, ACTA, Amsterdam (Netherlands); Galbiati, Valentina [Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano (Italy); Fuchs, Horst W. [CellSystems GmbH, Troisdorf (Germany); DeGeorge, George; Troese, Matthew [MB Research Labs, Spinnerstown, PA (United States); Hayden, Patrick; Deng, Wei [MatTek Corporation, Ashland, MA (United States); Roggen, Erwin [3Rs Management and Consultancy (Denmark)
The purpose of this study was to explore the possibility of combining the epidermal equivalent (EE) potency assay with the assay which assesses release of interleukin-18 (IL-18) to provide a single test for identification and classification of skin sensitizing chemicals, including chemicals of low water solubility or stability. A protocol was developed using different 3D-epidermal models including in house VUMC model, epiCS® (previously EST1000â"¢), MatTek EpiDermâ"¢ and SkinEthicâ"¢ RHE and also the impact of different vehicles (acetone:olive oil 4:1, 1% DMSO, ethanol, water) was investigated. Following topical exposure for 24 h to 17 contact allergens and 13 non-sensitizers a robust increase in IL-18 release was observed only after exposure to contact allergens. A putative prediction model is proposed from data obtained from two laboratories yielding 95% accuracy. Correlating the in vitro EE sensitizer potency data, which assesses the chemical concentration which results in 50% cytotoxicity (EE-EC{sub 50}) with human and animal data showed a superior correlation with human DSA{sub 05} (μg/cm{sup 2}) data (Spearman r = 0.8500; P value (two-tailed) = 0.0061) compared to LLNA data (Spearman r = 0.5968; P value (two-tailed) = 0.0542). DSA{sub 05} = induction dose per skin area that produces a positive response in 5% of the tested population Also a good correlation was observed for release of IL-18 (SI-2) into culture supernatants with human DSA{sub 05} data (Spearman r = 0.8333; P value (two-tailed) = 0.0154). This easily transferable human in vitro assay appears to be very promising, but additional testing of a larger chemical set with the different EE models is required to fully evaluate the utility of this assay and to establish a definitive prediction model. - Highlights: • A potential epidermal equivalent assay to label and classify sensitizers • Il-18 release distinguishes sensitizers from non sensitizers • IL-18 release can rank sensitizer potency â
Gibbs, Susan; Corsini, Emanuela; Spiekstra, Sander W.; Galbiati, Valentina; Fuchs, Horst W.; DeGeorge, George; Troese, Matthew; Hayden, Patrick; Deng, Wei; Roggen, Erwin
The purpose of this study was to explore the possibility of combining the epidermal equivalent (EE) potency assay with the assay which assesses release of interleukin-18 (IL-18) to provide a single test for identification and classification of skin sensitizing chemicals, including chemicals of low water solubility or stability. A protocol was developed using different 3D-epidermal models including in house VUMC model, epiCS® (previously EST1000™), MatTek EpiDerm™ and SkinEthic™ RHE and also the impact of different vehicles (acetone:olive oil 4:1, 1% DMSO, ethanol, water) was investigated. Following topical exposure for 24 h to 17 contact allergens and 13 non-sensitizers a robust increase in IL-18 release was observed only after exposure to contact allergens. A putative prediction model is proposed from data obtained from two laboratories yielding 95% accuracy. Correlating the in vitro EE sensitizer potency data, which assesses the chemical concentration which results in 50% cytotoxicity (EE-EC 50 ) with human and animal data showed a superior correlation with human DSA 05 (μg/cm 2 ) data (Spearman r = 0.8500; P value (two-tailed) = 0.0061) compared to LLNA data (Spearman r = 0.5968; P value (two-tailed) = 0.0542). DSA 05 = induction dose per skin area that produces a positive response in 5% of the tested population Also a good correlation was observed for release of IL-18 (SI-2) into culture supernatants with human DSA 05 data (Spearman r = 0.8333; P value (two-tailed) = 0.0154). This easily transferable human in vitro assay appears to be very promising, but additional testing of a larger chemical set with the different EE models is required to fully evaluate the utility of this assay and to establish a definitive prediction model. - Highlights: • A potential epidermal equivalent assay to label and classify sensitizers • Il-18 release distinguishes sensitizers from non sensitizers • IL-18 release can rank sensitizer potency • EC50 (chemical
Differential gene expression responses distinguish contact and respiratory sensitizers and nonsensitizing irritants in the local lymph node assay.
Adenuga, David; Woolhiser, Michael R; Gollapudi, B Bhaskar; Boverhof, Darrell R
Genomic approaches have the potential to enhance the specificity and predictive accuracy of existing toxicology endpoints, including those for chemical sensitization. The present study was conducted to determine whether gene expression responses can distinguish contact sensitizers (1-chloro-2,4-dinitrobenzene [DNCB] and hexyl cinnamic aldehyde [HCA]), respiratory sensitizers (ortho-phthalaldehyde and trimellitic anhydride [TMA]), and nonsensitizing irritants (methyl salicylate [MS] and nonanoic acid [NA]) in the local lymph node assay (LLNA). Female Balb/c mice received doses of each chemical as per the standard LLNA dosing regimen on days 1, 2, and 3. Auricular lymph nodes were analyzed for tritiated thymidine ((3)HTdR) incorporation on day 6 and for gene expression responses on days 6 and 10. All chemicals induced dose-dependent increases in stimulation index, which correlated strongly with the number of differentially expressed genes. A majority of genes modulated by the irritants were similarly altered by the sensitizers, consistent with the irritating effects of the sensitizers. However, a select number of responses involved with immune-specific functions, such as dendritic cell activation, were unique to the sensitizers and may offer the ability to distinguish sensitizers from irritants. Genes for the mast cell proteases 1 and 8, Lgals7, Tim2, Aicda, Il4, and Akr1c18 were more strongly regulated by respiratory sensitizers compared with contact sensitizers and may represent potential biomarkers for discriminating between contact and respiratory sensitizers. Collectively, these data suggest that gene expression responses may serve as useful biomarkers to distinguish between respiratory and contact sensitizers and nonsensitizing irritants in the LLNA.
Contact allergy to preservatives in patients with occupational contact dermatitis and exposure analysis of preservatives in registered chemical products for occupational use.
Schwensen, Jakob Ferløv; Friis, Ulrik Fischer; Menné, Torkil; Flyvholm, Mari-Ann; Johansen, Jeanne Duus
The aim of the study is to investigate risk factors for sensitization to preservatives and to examine to which extent different preservatives are registered in chemical products for occupational use in Denmark. A retrospective epidemiological observational analysis of data from a university hospital was conducted. All patients had occupational contact dermatitis and were consecutively patch tested with 11 preservatives from the European baseline series and extended patch test series during a 5-year period: 2009-2013. Information regarding the same preservatives in chemical products for occupational use ('substances and materials') registered in the Danish Product Register Database (PROBAS) was obtained. The frequency of preservative contact allergy was 14.2% (n = 141) in 995 patients with occupational contact dermatitis. Patients with preservative contact allergy had significantly more frequently facial dermatitis (19.9 versus 13.1%) and age > 40 years (71.6 versus 45.8%) than patients without preservative contact allergy, whereas atopic dermatitis was less frequently observed (12.1 versus 19.8%). Preservative contact allergy was more frequent in painters with occupational contact dermatitis as compared to non-painters with occupational contact dermatitis (p contact allergy to methylisothiazolinone and contact allergy to formaldehyde. Analysis of the registered substances and materials in PROBAS revealed that preservatives occurred in several product categories, e.g., 'paints and varnishes', 'cleaning agents', 'cooling agents', and 'polishing agents'. Formaldehyde and isothiazolinones were extensively registered in PROBAS. The extensive use of formaldehyde and isothiazolinones in chemical products for occupational use may be problematic for the worker. Appropriate legislation, substitution, and employee education should be prioritized.
Highly sensitive MoS2 photodetectors with graphene contacts
Han, Peize; St. Marie, Luke; Wang, Qing X.; Quirk, Nicholas; El Fatimy, Abdel; Ishigami, Masahiro; Barbara, Paola
Two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) are ideal candidates to create ultra-thin electronics suitable for flexible substrates. Although optoelectronic devices based on TMDs have demonstrated remarkable performance, scalability is still a significant issue. Most devices are created using techniques that are not suitable for mass production, such as mechanical exfoliation of monolayer flakes and patterning by electron-beam lithography. Here we show that large-area MoS2 grown by chemical vapor deposition and patterned by photolithography yields highly sensitive photodetectors, with record shot-noise-limited detectivities of 8.7 × 1014 Jones in ambient condition and even higher when sealed with a protective layer. These detectivity values are higher than the highest values reported for photodetectors based on exfoliated MoS2. We study MoS2 devices with gold electrodes and graphene electrodes. The devices with graphene electrodes have a tunable band alignment and are especially attractive for scalable ultra-thin flexible optoelectronics.
Dendritic cells' death induced by contact sensitizers is controlled by Nrf2 and depends on glutathione levels
El Ali, Zeina [UMR996 - Inflammation, Chemokines and Immunopathology-, INSERM, Univ Paris-Sud, Université Paris-Saclay, 92296 Châtenay-Malabry (France); Deloménie, Claudine [IFR141 IPSIT, Univ Paris-Sud, Université Paris-Saclay, Châtenay-Malabry (France); Botton, Jérémie [INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Team (France); Pallardy, Marc [UMR996 - Inflammation, Chemokines and Immunopathology-, INSERM, Univ Paris-Sud, Université Paris-Saclay, 92296 Châtenay-Malabry (France); Kerdine-Römer, Saadia, E-mail: saadia.kerdine-romer@u-psud.fr [UMR996 - Inflammation, Chemokines and Immunopathology-, INSERM, Univ Paris-Sud, Université Paris-Saclay, 92296 Châtenay-Malabry (France)
Dendritic cells (DC) are known to play a major role during contact allergy induced by contact sensitizers (CS). Our previous studies showed that Nrf2 was induced in DC and controlled allergic skin inflammation in mice in response to chemicals. In this work, we raised the question of the role of Nrf2 in response to a stress provoked by chemical sensitizers in DC. We used two well-described chemical sensitizers, dinitrochlorobenzene (DNCB) and cinnamaldehyde (CinA), known to have different chemical reactivity and mechanism of action. First, we performed a RT-qPCR array showing that CinA was a higher inducer of immune and detoxification genes compared to DNCB. Interestingly, in the absence of Nrf2, gene expression was dramatically affected in response to DNCB but was slightly affected in response to CinA. These observations prompted us to study DC's cell death in response to both chemicals. DNCB and CinA increased apoptotic cells and decreased living cells in the absence of Nrf2. The characterization of DC apoptosis induced by both CS involved the mitochondrial-dependent caspase pathway and was regulated via Nrf2 in response to both chemicals. Oxidative stress induced by DNCB, and leading to cell death, was regulated by Nrf2. Unlike CinA, DNCB treatment provoked a significant reduction of intracellular GSH levels and up-regulated bcl-2 gene expression, under the control of Nrf2. This work underlies that chemical reactivity may control Nrf2-dependent gene expression leading to different cytoprotective mechanisms in DC. - Highlights: • Nrf2 controls cell death induced by contact sensitizers in dendritic cells. • DNCB reduced GSH levels and up-regulated bcl-2 gene expression unlike CinA. • Chemical reactivity controls Nrf2-dependent genes having protective effect in DC.
INFLUENCE OF MODIFIED BIOFLAVONOIDS UPON EFFECTOR LYMPHOCYTES IN MURINE MODEL OF CONTACT SENSITIVITY
D. Z. Albegova
Full Text Available Contact sensitivity reaction (CSR to 2,4-dinitrofluorobenzene (DNFB in mice is a model of in vivo immune response, being an experimental analogue to contact dermatitis in humans. CSR sensitization phase begins after primary contact with antigen, lasting for 10-15 days in humans, and 5-7 days, in mice. Repeated skin exposure to the sensitizing substance leads to its recognition and triggering immune inflammatory mechanisms involving DNFB-specific effector T lymphocytes. The CSR reaches its maximum 18-48 hours after re-exposure to a hapten. There is only scarce information in the literature about effects of flavonoids on CSR, including both stimulatory and inhibitory effects. Flavonoids possessed, predominantly, suppressive effects against the CSR development. In our laboratory, a model of contact sensitivity was reproduced in CBA mice by means of cutaneous sensitization by 2,4-dinitrofluorobenzene. The aim of the study was to identify the mechanisms of immunomodulatory action of quercetin dihydrate and modified bioflavonoids, using the method of adoptive transfer contact sensitivity by splenocytes and T-lymphocytes. As shown in our studies, a 30-min pre-treatment of splenocytes and T-lymphocytes from sensitized mice with modified bioflavonoids before the cell transfer caused complete prevention of contact sensitivity reaction in syngeneic recipient mice. Meanwhile, this effect was not associated with cell death induction due to apoptosis or cytotoxicity. Quercetin dihydrate caused only partially suppression the activity of adaptively formed T-lymphocytes, the contact sensitivity effectors. It was shown that the modified bioflavonoid more stronger suppress adoptive transfer of contact sensitivity in comparison with quercetin dehydrate, without inducing apoptosis of effector cells. Thus, the modified bioflavonoid is a promising compound for further studies in a model of contact sensitivity, due to its higher ability to suppress transfer of CSR with
Tc1-mediated contact sensitivity reaction, its mechanism and regulation
Magdalena Zemelka-WiÄ…cek
Full Text Available The contact hypersensitivity reaction (CHS to haptens is a classic example of cell-mediated immune response. In the effector phase, two stages can be distinguished: an early component, that appears only 2 hours after subsequent contact with the hapten, and the late component that develops approximately 24 hours later which is mediated by TCRαβ+ cells. The effector lymphocytes may be CD4+ T helper 1 (Th1 cells or CD8+ T cytotoxic 1 (Tc1 cells, which depends on the employed hapten and/or mice strain. NKT lymphocytes play the crucial role in the CHS initiation, by supporting B1 cells in the antigen-specific IgM antibodies production. The development of an early component is essential for the recruitment of T effector (Teff cells to the side of hapten deposition and for the complete expansion of inflammatory reaction. The CHS reaction is under T regulatory (Treg cells control, both in the induction phase as well as in the effector phase. A new view of a negative regulation of the Tc1 mediated CHS response is based on the suppression induced by epicutaneous (EC application of protein antigen. The DNP-BSA skin application, on a gauze patch, leads to a state of immunosuppression. This maneuver results in rising the population of Treg cells with TCRαβ+CD4+CD25+Foxp3+ phenotype. The mechanism of suppression requires direct contact between Treg cells and Teff cells and the participation of CTLA-4 molecule is also necessary. The described method of evoking immune tolerance via EC immunization may contribute to elaborate a new method of allergic contact dermatitis therapy. This is because of its effectiveness, ease of induction and non-invasive protein antigen application.
Contact and respiratory sensitizers can be identified by cytokine profiles following inhalation exposure
Jong, W.H. de; Arts, J.H.E.; Klerk, A. de; Schijf, M.A.; Ezendam, J.; Kuper, C.F.; Loveren, H. van
There are currently no validated animal models that can identify low molecular weight (LMW) respiratory sensitizers. The Local Lymph Node Assay (LLNA) is a validated animal model developed to detect contact sensitizers using skin exposure, but all LMW respiratory sensitizers tested so far were also
De Jong, Wim H.; Arts, Josje H.E.; De Klerk, Arja; Schijf, Marcel A.; Ezendam, Janine; Kuper, C. Frieke; Van Loveren, Henk
There are currently no validated animal models that can identify low molecular weight (LMW) respiratory sensitizers. The Local Lymph Node Assay (LLNA) is a validated animal model developed to detect contact sensitizers using skin exposure, but all LMW respiratory sensitizers tested so far were also positive in this assay. Discrimination between contact and respiratory sensitizers can be achieved by the assessment of cytokine profiles. In a LLNA using the inhalation route, both contact and respiratory sensitizers enhanced proliferation in the draining lymph nodes. The question was if their cytokine profiles were affected by the route of exposure. Male BALB/c mice were exposed head/nose-only during 3 consecutive days to the respiratory sensitizers trimellitic anhydride, phthalic anhydride, toluene diisocyanate, hexamethylene diisocyanate (HDI), and isophorone diisocyanate; the contact sensitizers dinitrochlorobenzene (DNCB), oxazolone (OXA) and formaldehyde (FA), and the irritant methyl salicylate (MS). Three days after the last exposure the draining lymph nodes were excised and cytokine production was measured after ex vivo stimulation with Concanavalin A. Skin application was used as a positive control. After inhalation exposure the respiratory sensitizers induced more interleukin-4 (IL-4) and interleukin (IL-10) compared to the contact sensitizers, whereas the contact sensitizers, except formaldehyde, induced relatively more interferon-γ (IFN-γ) production. When IL-4 and IFN-γ were plotted as a function of the proliferative response, it was shown that IL-4 could be used to identify respiratory sensitizers, except HDI, at concentration levels inducing intermediate stimulation indices. HDI could be distinguished from DNCB and OXA at high SI values. In contrast, contact sensitizers could only be identified when IFN-γ was measured at high stimulation indices. The skin positive control, tested at high concentrations, showed comparable results for IL-4 and IL-10
Immune suppression with supraoptimal doses of antigen in contact sensitivity. I. Demonstration of suppressor cells and their sensitivity to cyclophosphamide.
Sy, M S; Miller, S D; Claman, H N
Immunologic suppression was induced in a mouse model of contact sensitization to DNFB by using supraoptimal doses of antigen. In these studies, in vivo measurement of ear swelling as an indication of immunologic responsiveness correlated well with measurement of in vitro antigen-induced cell proliferation. This unresponsiveness was specific, since supraoptimal doses of DNFB did not interfere with the development of contact sensitivity to another contactant, oxazolone. The decrease in responsiveness is a form of active suppression, as lymphoid cells from supraoptimally sensitized donors transferred suppression to normal recipients. Furthermore, pretreatment with cyclophosphamide (Cy) reversed the suppression seen in supraoptimally sensitized animals but had no effect on the optimal sensitization regimen. These results indicate that supraoptimal doses of contactants can activate suppressor cells and that precursors of these cells are sensitive to Cy. Such suppressors regenerate within 7 to 14 days after Cy treatment. The ability of Cy pretreatment to affect supraoptimal sensitization without affecting optimal sensitization confirms other reports indicating that the observed results of Cy treatment depend critically upon the dose of antigen used.
Prevalence and effects of multiple chemical sensitivities in Australia
Anne Steinemann
Full Text Available Multiple chemical sensitivities (MCS is a medical condition associated with exposure to common chemical pollutants. The aims of this study are to assess the prevalence of MCS, its overlaps with asthma and fragrance sensitivity, and its health and societal effects in Australia. Data were collected in June 2016 using an on-line survey with a representative national sample (N = 1098 of adults (ages 18–65 in Australia. Results found that, across the country, 6.5% report medically diagnosed MCS, 18.9% report chemical sensitivity (being unusually sensitive to everyday chemicals and chemically formulated products, and 19.9% either or both. Among people with MCS, 74.6% also have diagnosed asthma or an asthma-like condition, and 91.5% have fragrance sensitivity, reporting health problems (such as migraine headaches when exposed to fragranced consumer products (such as air fresheners and cleaning supplies. In addition, among people with MCS, 77.5% are prevented from access to places because of fragranced products, 52.1% lost workdays or a job in the past year due to fragranced product exposure in the workplace, and 55.4% report health effects considered potentially disabling. Results indicate that MCS is a widespread disease, affecting an estimated 1 million adult Australians, with chemical sensitivity affecting another 2 million. Reducing chemical exposure to problematic sources, such as fragranced consumer products, is critical to reduce adverse effects. Keywords: MCS, Multiple chemical sensitivities, Chemical sensitivity, Asthma, Fragrance sensitivity, Fragranced consumer products
[Epidemiology of contact dermatitis: prevalence of sensitization to different allergens and associated factors].
Bordel-Gómez, Ma T; Miranda-Romero, A; Castrodeza-Sanz, J
In clinical practice, contact dermatitis is a relatively common skin complaint, whose prevalence has increased in recent years. Study by patch testing is essential for diagnosis of contact sensitization. To study the prevalence of sensitization to different allergens in a standard battery and observe the influence of different epidemiological and clinical variables on contact sensitization. A large number of allergens were included in our battery in order to detect new sensitizations whose prevalence might justify further study. This was a retrospective, observational, epidemiological study of 1092 patients, conducted in our skin allergy unit between January 1, 2000, and December 31, 2005. All patients were studied with a battery of 51 allergens. We assessed the following variables: sex, age, type of referral, occupation, site and course of skin lesions, personal and family history of atopy, positive patch tests, clinical significance, diagnosis, source of sensitization, and occupational relationship. At least 1 positive result was found in 55% of the patients, and 55.7% presented atopic dermatitis in one of its clinical variants: allergic contact dermatitis (28.2%), irritant contact dermatitis (20.1%), photoallergic contact dermatitis (2.2%), and phototoxic contact dermatitis (1.2%). The most prevalent allergens were nickel sulfate (29.3%), palladium chloride (11.7%), cobalt chloride (10.8%), potassium dichromate (7.5%), fragrance blends (6.3%), and p-phenylenediamine (6.1%). A positive occupational relationship was found in 41.1%, and 21.3% of the patients studied were diagnosed with occupational contact dermatitis. Metal workers, construction workers, and professional hairdressers were the most strongly represented groups. The most common source of sensitization was contact with metallic objects, followed by drugs, cosmetics, and rubber items. Female sex was the only independent variable that had a significant influence on the risk of contact sensitization in
Human sensitivity to eye contact in 2D and 3D videoconferencing
Eijk, van R.L.J.; Kuijsters, A.; Dijkstra, K.I.; IJsselsteijn, W.A.
Gaze awareness and eye contact serve important functions in social interaction. In order to maintain those functions in 2D and 3D videoconferencing systems, human sensitivity to eye contact and gaze direction needs to be taken into account in the design of such systems. Here we experimentally
Contact sensitization in Dutch children and adolescents with and without atopic dermatitis - a retrospective analysis
Lubbes, Stefanie; Rustemeyer, Thomas; Smitt, Johannes H. Sillevis; Schuttelaar, Marie-Louise A.; Middelkamp-Hup, Maritza A
Background. Allergic contact dermatitis is known to occur in children with and without atopic dermatitis, but more data are needed on contact sensitization profiles in these two groups. Objectives. To identify frequent allergens in children with and without atopic dermatitis suspected of having
Multiple chemical sensitivity, en veldefineret lidelse?
Kolstad, Henrik A.; Silberschmidt, Martin; Nielsen, Jesper Bo
, even though a number of theories have been proposed. The authors of this review conclude that this is a functional condition. These patients need information and treatment in accordance with this fact. Instead of being advised how to avoid exposure to chemicals, they should be properly trained...... in appropriate confrontation with the chemicals encountered in everyday life....
Surface charging, discharging and chemical modification at a sliding contact
Singh, Shailendra Vikram; Kusano, Yukihiro; Morgen, Per
Electrostatic charging, discharging, and consequent surface modification induced by sliding dissimilar surfaces have been studied. The surface-charge related phenomena were monitored by using a home-built capacitive, non-contact electrical probe, and the surface chemistry was studied by X...... are also able to comment on the behavior and the charge decay time in the ambient air-like condition, once the sliding contact is discontinued. XPS analysis showed a marginal deoxidation effect on the polyester disks due to the charging and discharging of the surfaces. Moreover, these XPS results clearly...
Sensitive Diagnostics for Chemically Reacting Flows
Farooq, Aamir
This talk will feature latest diagnostic developments for sensitive detection of gas temperature and important combustion species. Advanced optical strategies, such as intrapulse chirping, wavelength modulation, and cavity ringdown are employed.
Contact allergy to preservatives in patients with occupational contact dermatitis and exposure analysis of preservatives in registered chemical products for occupational use
Schwensen, Jakob Ferløv; Friis, Ulrik Fischer; Menné, Torkil
PURPOSE: The aim of the study is to investigate risk factors for sensitization to preservatives and to examine to which extent different preservatives are registered in chemical products for occupational use in Denmark. METHODS: A retrospective epidemiological observational analysis of data from...... a university hospital was conducted. All patients had occupational contact dermatitis and were consecutively patch tested with 11 preservatives from the European baseline series and extended patch test series during a 5-year period: 2009-2013. Information regarding the same preservatives in chemical products...... in several product categories, e.g., 'paints and varnishes', 'cleaning agents', 'cooling agents', and 'polishing agents'. Formaldehyde and isothiazolinones were extensively registered in PROBAS. CONCLUSIONS: The extensive use of formaldehyde and isothiazolinones in chemical products for occupational use may...
Sensitivity of animals to chemical compounds links to metabolic rate.
Baas, J.; Kooijman, S.A.L.M.
Ecotoxicological studies have shown considerable variation in species sensitivity for chemical compounds, but general patterns in sensitivity are still not known. A better understanding of this sensitivity is important in the context of environmental risk assessment but also in a more general
Evaluation of human skin tests for potential dermal irritant and contact sensitizing products: a position paper
Loveren H van; Jong WH de; Garssen J; LPI
Prediction of human cutaneous irritation and sensitization in view of hazard identification has primarily relied on the use of laboratory animals. Such studies in laboratory animals have been very instrumental in the detection of potential contact sensitizing agents. There are however many
Contact allergy to popular perfumes; assessed by patch test, use test and chemical analysis.
Johansen, J D; Rastogi, S C; Menné, T
The frequency of contact allergy to the 10 best-selling women's perfumes was studied in 335 consecutive female eczema patients by patch testing. The diagnostic ability of the fragrance mix, in relation to these products, was evaluated. Of eczema patients, 6.9% had a positive patch test to one or more of the perfumes, and 56.5% of these had a concurrent positive reaction to the fragrance mix. Hence, testing with the patients' own cosmetics is a significant part of diagnosing perfume allergy. The clinical relevance of the patch-test reactions to the commercial perfumes was equal to that of the fragrance mix, as judged from the patient's history and use testing with one of the perfumes. At least three of the chemically defined sensitizers in the fragrance mix were detected in all the perfumes by gas chromatography-mass spectrometry, which indicates that the fragrance mix is a good imitation of actual exposure.
Contact allergy to popular perfumes; assessed by patch test, use test and chemical analysis
Johansen, J D; Rastogi, Suresh Chandra; Menné, T
The frequency of contact allergy to the 10 best-selling women's perfumes was studied in 335 consecutive female eczema patients by patch testing. The diagnostic ability of the fragrance mix, in relation to these products, was evaluated. Of eczema patients, 6.9% had a positive patch test to one...... or more of the perfumes, and 56.5% of these had a concurrent positive reaction to the fragrance mix. Hence, testing with the patients' own cosmetics is a significant part of diagnosing perfume allergy. The clinical relevance of the patch-test reactions to the commercial perfumes was equal...... to that of the fragrance mix, as judged from the patient's history and use testing with one of the perfumes. At least three of the chemically defined sensitizers in the fragrance mix were detected in all the perfumes by gas chromatography-mass spectrometry, which indicates that the fragrance mix is a good imitation...
Genetic susceptibility factors for multiple chemical sensitivity revisited
Berg, Nikolaj Drimer; Rasmussen, Henrik Berg; Linneberg, Allan
of this study was to investigate genetic susceptibility factors for MCS and self-reported chemical sensitivity in a population sample. Ninety six MCS patients and 1,207 controls from a general population divided into four severity groups of chemical sensitivity were genotyped for variants in the genes encoding......Multiple chemical sensitivity (MCS) is characterised by adverse effects due to exposure to low levels of chemical substances. Various genes, especially genes of importance to the metabolism of xenobiotic compounds, have been associated with MCS, but findings are inconsistent. The purpose...... significant (OR=1.2, p=0.28). Fast arylamine N-acetyltransferase 2 metaboliser status was associated with severity of chemical sensitivity only in the most severely affected group in the population sample (OR=3.1, p=0.04). The cholecystokinin 2 receptor allele with 21 CT repeats was associated with MCS when...
Shoe contact dermatitis from dimethyl fumarate: clinical manifestations, patch test results, chemical analysis, and source of exposure.
Giménez-Arnau, Ana; Silvestre, Juan Francisco; Mercader, Pedro; De la Cuadra, Jesus; Ballester, Isabel; Gallardo, Fernando; Pujol, Ramón M; Zimerson, Erik; Bruze, Magnus
The methyl ester form of fumaric acid named dimethyl fumarate (DMF) is an effective mould-growth inhibitor. Its irritating and sensitizing properties were demonstrated in animal models. Recently, DMF has been identified as responsible for furniture contact dermatitis in Europe. To describe the clinical manifestations, patch test results, shoe chemical analysis, and source of exposure to DMF-induced shoe contact dermatitis. Patients with suspected shoe contact dermatitis were studied in compliance with the Declaration of Helsinki. Patch test results obtained with their own shoe and the European baseline series, acrylates and fumaric acid esters (FAE), were recorded according to international guidelines. The content of DMF in shoes was analysed with gas chromatography and mass spectrometry. Acute, immediate irritant contact dermatitis and non-immunological contact urticaria were observed in eight adults and two children, respectively. All the adult patients studied developed a delayed sensitization demonstrated by a positive patch testing to DMF Global preventive measures for avoiding contact with DMF are necessary.
A plasmacytoid dendritic cell (CD123+/CD11c-) based assay system to predict contact allergenicity of chemicals
Ayehunie, Seyoum; Snell, Maureen; Child, Matthew; Klausner, Mitchell
A predictive allergenicity test system for assessing the contact allergenicity of chemicals is needed by the cosmetic and pharmaceutical industry to monitor product safety in the marketplace. Development of such non-animal alternative assay systems for skin sensitization and hazard identification has been pursued by policy makers and regulatory agencies. We investigated whether phenotypic and functional changes to a subset of dendritic cells (DC), plasmacytoid DC (pDC), could be used to identify contact allergens. To achieve this goal, normal human DC were generated from CD34+ progenitor cells and cryopreserved. Frozen DC were thawed and the pDC fraction (CD123+/CD11c-) was harvested using FACS sorting. The pDC were cultured, expanded, and exposed to chemical allergens (N=26) or non-allergens (N=22). Concentrations of each chemical that resulted in >50% viability was determined using FACS analysis of propidium iodide stained cells using pDC from 2-5 donors. Expression of the surface marker, CD86, which has been implicated in dendritic cell maturation, was used as a marker of allergenicity. CD86 expression increased (≥ 1.5 fold) for 25 of 26 allergens (sensitivity = 96%) but did not increase for 19 of 22 non-allergens (specificity = 86%). In a direct comparison to historical data for the regulatory approved, mouse local lymph node assay (LLNA) for 23 allergens and 22 non-allergens, the pDC method had sensitivity and specificity of 96% and 86%, respectively, while the sensitivity and specificity of the LLNA assay was 83% and 82%, respectively. In conclusion, CD86 expression in pDC appears to be a sensitive and specific indicator to identify contact allergenicity. Such an assay method utilizing normal human cells will be useful for high throughput screening of chemicals for allergenicity. PMID:19665512
A predictive allergenicity test system for assessing the contact allergenicity of chemicals is needed by the cosmetic and pharmaceutical industry to monitor product safety in the marketplace. Development of such non-animal alternative assay systems for skin sensitization and hazard identification has been pursued by policy makers and regulatory agencies. We investigated whether phenotypic and functional changes to a subset of dendritic cells (DC), plasmacytoid DC (pDC), could be used to identify contact allergens. To achieve this goal, normal human DC were generated from CD34+ progenitor cells and cryopreserved. Frozen DC were thawed and the pDC fraction (CD123+/CD11c-) was harvested using FACS sorting. The pDC were cultured, expanded, and exposed to chemical allergens (N = 26) or non-allergens (N = 22). Concentrations of each chemical that resulted in >50% viability was determined using FACS analysis of propidium iodide stained cells using pDC from 2 to 5 donors. Expression of the surface marker, CD86, which has been implicated in dendritic cell maturation, was used as a marker of allergenicity. CD86 expression increased (≥1.5-fold) for 25 of 26 allergens (sensitivity = 96%) but did not increase for 19 of 22 non-allergens (specificity = 86%). In a direct comparison to historical data for the regulatory approved, mouse local lymph node assay (LLNA) for 23 allergens and 22 non-allergens, the pDC method had sensitivity and specificity of 96% and 86%, respectively, while the sensitivity and specificity of the LLNA assay was 83% and 82%, respectively. In conclusion, CD86 expression in pDC appears to be a sensitive and specific indicator to identify contact allergenicity. Such an assay method utilizing normal human cells will be useful for high throughput screening of chemicals for allergenicity.
The safety and efficacy of contact lens wear in the industrial and chemical workplace.
Tyhurst, Keith; McNett, Ryan; Bennett, Edward
The use and safety of contact lenses in the industrial and chemical workplace has often been questioned since the 1960s because of many unconfirmed reports of ocular injury resulting from contact lens wear. Because of these urban legends, contact lens wear has been banned or wearers have been required to wear additional personal protective equipment (PPE) not required of non-contact lens wearers. Literature review via Medline and Google search. Research has shown that contact lenses typically provide protective benefits that decrease the severity of ocular injury and improve worker performance. While contact lens wear contraindications do exist, in most cases, and with proper precautions, contact lens wear is still possible. Industrial and chemical companies need to establish written contact lens use policies based on current studies that have shown the safety of workplace contact lens wear when combined with the same PPE required of non-contact lens wearers. Practitioners need to discuss, with their contact lens patients, the additional responsibilities required to maintain proper lens hygiene and proper PPE in the workplace.
Chemical identification of contaminants in paper and board food contact materials
Bengtström, Linda
Paper and board are used for a variety of food contact materials, such as baking paper, microwave popcorn bags and packaging for cereals as well as fast foods. Despite this extensive use, there are currently large data gaps about the chemical composition of different paper and board food contact...
Contact Irritant Responses of Aedes aegypti Using Sublethal Concentration and Focal Application of Pyrethroid Chemicals
Manda, Hortance; Shah, Pankhil; Polsomboon, Suppaluck; Chareonviriyaphap, Theeraphap; Castro-Llanos, Fanny; Morrison, Amy; Burrus, Roxanne G.; Grieco, John P.; Achee, Nicole L.
BACKGROUND: Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application. METHODS: Cont...
The Possible Role of Contact Sensitization to Fragrances and Preservatives in Poikiloderma of Civatte
Khunkhet S; Wattanakrai P
Numerous mechanisms have been postulated to play an important role in the pathogenesis of poikiloderma of Civatte, including chronic exposure to ultraviolet radiation, menopause-related hormonal changes, contact hypersensitivity and genetic predisposition. Herein, we report a case of contact sensitization to fragrances and commonly used preservatives, methylchloroisothiazolinone and methylisothiazolinone, also widely known as Kathon CG, in a post-menopausal woman with poikiloderma of Civatte,...
Khunkhet, Saranya; Wattanakrai, Penpun
Numerous mechanisms have been postulated to play an important role in the pathogenesis of poikiloderma of Civatte (PC), including chronic exposure to ultraviolet radiation, menopause-related hormonal changes, contact hypersensitivity and genetic predisposition. Herein, we report a case of contact sensitization to fragrances and commonly used preservatives, methylchloroisothiazolinone and methylisothiazolinone, also widely known as Kathon CG, in a post-menopausal woman with PC, who denied exce...
CONTACT DERMATITIS TO METHYLDIBROMOGLUTARONITRILE: EMERGENCE OF SENSITIZATION IN THE CENTRAL REGION OF TUNISIA
Maher Maoua
Full Text Available Methyldibromoglutaronitrile (MDBGN is a preservative found in cosmetics as well as in products for industrial use. It caused an outbreak of allergic contact dermatitis in Europe in the 1990s and early 2000s. To assess the prevalence of MDBGN sensitization among consultants in the occupational dermato-allergology unit of Farhat Hached University Hospital in Sousse-Tunisia, we carried out a study of all cases of contact dermatitis to MDBGN confirmed by patch-tests from 1 January 2011 to 31 December 2015. The prevalence of allergic contact dermatitis to MDBGN was 4.5% of all cases of contact dermatitis recorded during the same period with an increase from 1.7% in 2011 to 5.4% in 2015. Associated allergens with contact dermatitis to MDBGN were the Peru balsam in 4 cases, nickel sulfate and kathon CG in 3 cases each. Contact dermatitis to Dibromodicyanobutane was associated with sensitization to other preservatives in 4 cases and cosmetic allergens in 6 cases. An increasing rates of sensitization are noticed in our region. The absence of legal restrictions regarding this preservative agent may explain an increase of its use in non-European countries.
Hair dye dermatitis and p-phenylenediamine contact sensitivity: A preliminary report
Mrinal Gupta
Full Text Available Background: The contact allergic reactions from p-phenylenediamine (PPD in hair dyes vary from mild contact dermatitis to severe life- threatening events (angioedema, bronchospasm, asthma, renal impairment. Objectives: To study the clinical patterns and PPD contact sensitivity in patients with hair-dye dermatitis. Materials and Methods: Eighty (M: F 47:33 consecutive patients aged between 18 and 74 years suspected to have contact allergy from hair dye were studied by patch testing with Indian Standard Series including p-phenylenediamine (PPD, 1.0% pet. Results: 54 Fifty-four (M: F 21:33 patients showed positive patch tests from PPD. Eight of these patients also showed positive patch test reaction from fragrance mix, thiuram mix, paraben mix, or colophony. Fifty-seven (71% patients affected were aged older than 40 years. The duration of dermatitis varied from 1 year with exacerbation following hair coloring. Forty-nine patients had dermatitis of scalp and/or scalp margins and 23 patients had face and neck dermatitis. Periorbital dermatitis, chronic actinic dermatitis, and erythema multiforme-like lesions were seen in 4, 2, and 1 patients, respectively. Conclusions: Hair dyes and PPD constitute a significant cause of contact dermatitis. There is an urgent need for creating consumer awareness regarding hair-dyes contact sensitivity and the significance of performing sensitivity testing prior to actual use.
Hyperspectral monitoring of chemically sensitive plant sentinels
Simmons, Danielle A.; Kerekes, John P.; Raqueno, Nina G.
Automated detection of chemical threats is essential for an early warning of a potential attack. Harnessing plants as bio-sensors allows for distributed sensing without a power supply. Monitoring the bio-sensors requires a specifically tailored hyperspectral system. Tobacco plants have been genetically engineered to de-green when a material of interest (e.g. zinc, TNT) is introduced to their immediate vicinity. The reflectance spectra of the bio-sensors must be accurately characterized during the de-greening process for them to play a role in an effective warning system. Hyperspectral data have been collected under laboratory conditions to determine the key regions in the reflectance spectra associated with the degreening phenomenon. Bio-sensor plants and control (nongenetically engineered) plants were exposed to TNT over the course of two days and their spectra were measured every six hours. Rochester Institute of Technologys Digital Imaging and Remote Sensing Image Generation Model (DIRSIG) was used to simulate detection of de-greened plants in the field. The simulated scene contains a brick school building, sidewalks, trees and the bio-sensors placed at the entrances to the buildings. Trade studies of the bio-sensor monitoring system were also conducted using DIRSIG simulations. System performance was studied as a function of field of view, pixel size, illumination conditions, radiometric noise, spectral waveband dependence and spectral resolution. Preliminary results show that the most significant change in reflectance during the degreening period occurs in the near infrared region.
The cytokine-dependent MUTZ-3 cell line as an in vitro model for the screening of contact sensitizers
Azam, Philippe; Peiffer, Jean-Luc; Chamousset, Delphine; Tissier, Marie-Helene; Bonnet, Pierre-Antoine; Vian, Laurence; Fabre, Isabelle; Ourlin, Jean-Claude
Langerhans cells (LC) are key mediators of contact allergenicity in the skin. However, no in vitro methods exist which are based on the activation process of LC to predict the sensitization potential of chemicals. In this study, we have evaluated the performances of MUTZ-3, a cytokine-dependent human monocytic cell line, in its response to sensitizers. First, we compared undifferentiated MUTZ-3 cells with several standard human cells such as THP-1, KG-1, HL-60, K-562, and U-937 in their response to the strong sensitizer DNCB and the irritant SDS by monitoring the expression levels of HLA-DR, CD54, and CD86 by flow cytometry. Only MUTZ-3 and THP-1 cells show a strong and specific response to sensitizer, while other cell lines showed very variable responses. Then, we tested MUTZ-3 cells against a wider panel of sensitizers and irritants on a broader spectrum of cell surface markers (HLA-DR, CD40, CD54, CD80, CD86, B7-H1, B7-H2, B7-DC). Of these markers, CD86 proved to be the most reliable since it detected all sensitizers, including benzocaine, a classical false negative in local lymph node assay (LLNA) but not irritants. We confirmed the MUTZ-3 response to DNCB by real-time PCR analysis. Taken together, our data suggest that undifferentiated MUTZ-3 cells may represent a valuable in vitro model for the screening of potential sensitizers
Predicting a contact's sensitivity to initial conditions using metrics of frictional coupling
Flicek, Robert C.; Hills, David A.; Brake, Matthew Robert W.
This paper presents a method for predicting how sensitive a frictional contact's steady-state behavior is to its initial conditions. Previous research has proven that if a contact is uncoupled, i.e. if slip displacements do not influence the contact pressure distribution, then its steady-state response is independent of initial conditions, but if the contact is coupled, the steady-state response depends on initial conditions. In this paper, two metrics for quantifying coupling in discrete frictional systems are examined. These metrics suggest that coupling is dominated by material dissimilarity due to Dundurs' composite material parameter β when β ≥ 0.2, but geometric mismatch becomes the dominant source of coupling for smaller values of β. Based on a large set of numerical simulations with different contact geometries, material combinations, and friction coefficients, a contact's sensitivity to initial conditions is found to be correlated with the product of the coupling metric and the friction coefficient. For cyclic shear loading, this correlation is maintained for simulations with different contact geometries, material combinations, and friction coefficients. Furthermore, for cyclic bulk loading, the correlation is only maintained when the contact edge angle is held constant.
Defect-engineered graphene chemical sensors with ultrahigh sensitivity.
Lee, Geonyeop; Yang, Gwangseok; Cho, Ara; Han, Jeong Woo; Kim, Jihyun
We report defect-engineered graphene chemical sensors with ultrahigh sensitivity (e.g., 33% improvement in NO2 sensing and 614% improvement in NH3 sensing). A conventional reactive ion etching system was used to introduce the defects in a controlled manner. The sensitivity of graphene-based chemical sensors increased with increasing defect density until the vacancy-dominant region was reached. In addition, the mechanism of gas sensing was systematically investigated via experiments and density functional theory calculations, which indicated that the vacancy defect is a major contributing factor to the enhanced sensitivity. This study revealed that defect engineering in graphene has significant potential for fabricating ultra-sensitive graphene chemical sensors.
National Prevalence and Effects of Multiple Chemical Sensitivities.
Steinemann, Anne
The aim of this study was to assess the prevalence of multiple chemical sensitivities (MCS), its co-occurrence with asthma and fragrance sensitivity, and effects from exposure to fragranced consumer products. A nationally representative cross-sectional population-based sample of adult Americans (n = 1137) was surveyed in June 2016. Among the population, 12.8% report medically diagnosed MCS and 25.9% report chemical sensitivity. Of those with MCS, 86.2% experience health problems, such as migraine headaches, when exposed to fragranced consumer products; 71.0% are asthmatic; 70.3% cannot access places that use fragranced products such as air fresheners; and 60.7% lost workdays or a job in the past year due to fragranced products in the workplace. Prevalence of diagnosed MCS has increased over 300%, and self-reported chemical sensitivity over 200%, in the past decade. Reducing exposure to fragranced products could help reduce adverse health and societal effects.
Gibbs, S.; Corsini, E.; Spiekstra, S.W.; Galbiati, V.; Fuchs, H.W.; Degeorge, G.; Troese, M.; Hayden, P.; Deng, W.; Roggen, E.
The purpose of this study was to explore the possibility of combining the epidermal equivalent (EE) potency assay with the assay which assesses release of interleukin-18 (IL-18) to provide a single test for identification and classification of skin sensitizing chemicals, including chemicals of low
Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties
Madsen, Jakob Torp; Vogel, Stefan; Johansen, Jeanne Duus
Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens...... in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug...... dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed...
Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens...... in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug...... dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed...
Nickel contact sensitivity in the guinea pig. An efficient open application test method
Nielsen, G D; Rohold, A E; Andersen, Klaus Ejner
Nickel contact sensitivity was successfully induced in guinea pigs using an open epicutaneous application method. Immediately after pretreatment with 1% aqueous sodium lauryl sulfate, upper back skin was treated daily for 4 weeks with 0.3%-3% nickel sulfate in either a 1% lanolin cream (Vaseline, p...
Effects of symbiotic bacteria on chemical sensitivity of Daphnia magna.
Manakul, Patcharaporn; Peerakietkhajorn, Saranya; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime
The crustacean zooplankton Daphnia magna has been widely used for chemical toxicity tests. Although abiotic factors have been well documented in ecotoxicological test protocols, biotic factors that may affect the sensitivity to chemical compounds remain limited. Recently, we identified symbiotic bacteria that are critical for the growth and reproduction of D. magna. The presence of symbiotic bacteria on Daphnia raised the question as to whether these bacteria have a positive or negative effect on toxicity tests. In order to evaluate the effects of symbiotic bacteria on toxicity tests, bacteria-free Daphnia were prepared, and their chemical sensitivities were compared with that of Daphnia with symbiotic bacteria based on an acute immobilization test. The Daphnia with symbiotic bacteria showed higher chemical resistance to nonylphenol, fenoxycarb, and pentachlorophenol than bacteria-free Daphnia. These results suggested potential roles of symbiotic bacteria in the chemical resistance of its host Daphnia. Copyright © 2017 Elsevier Ltd. All rights reserved.
The prevalence of allergic contact sensitization in a general population in Tromsø, Norway.
Dotterud, Lars KÃ¥re
This study investigated the prevalence of contact sensitization in a general adult population and the relationship between the history of metal dermatitis and sensitization to metal allergens. A cross-sectional population study using patch tests and a questionnaire was conducted among adults in Tromsø, Northern Norway. A random sample of 830 participants aged 18-75 years were invited to participate in the patch testing and completed a 1-page self-administered questionnaire. Of the adults, 531 (64%) were actually TRUE tested (using a standardized, ready-to-apply patch test system) and completed the self-administered questionnaire about ear piercing, metal reactions, skin reactions to different allergens, atopic dermatitis, eczema, cooking equipment and diet. The study showed that nickel (19.2%; women 31.1% and men 5.0%), fragrance mix (3.4%) and cobalt (1.7%) were the most prevalent allergens causing contact sensitization. For all other allergens, less than 1.1% tested positive. Eighty-four (45.2%) subjects with a positive history of metal dermatitis had negative patch tests. Contact sensitization was found frequently in this general adult population, especially to nickel and perfumes with a predominance among females. An eczematous reaction caused by cheap earrings seemed to be the best indicator for metal sensitivity.
Determination of contact maps in proteins: A combination of structural and chemical approaches
Wołek, Karol; Cieplak, Marek, E-mail: mc@ifpan.edu.pl [Institute of Physics, Polish Academy of Science, Al. Lotników 32/46, 02-668 Warsaw (Poland); Gómez-Sicilia, Àngel [Instituto Cajal, Consejo Superior de Investigaciones Cientificas (CSIC), Av. Doctor Arce, 37, 28002 Madrid (Spain); Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), C/Faraday 9, 28049 Cantoblanco (Madrid) (Spain)
Contact map selection is a crucial step in structure-based molecular dynamics modelling of proteins. The map can be determined in many different ways. We focus on the methods in which residues are represented as clusters of effective spheres. One contact map, denoted as overlap (OV), is based on the overlap of such spheres. Another contact map, named Contacts of Structural Units (CSU), involves the geometry in a different way and, in addition, brings chemical considerations into account. We develop a variant of the CSU approach in which we also incorporate Coulombic effects such as formation of the ionic bridges and destabilization of possible links through repulsion. In this way, the most essential and well defined contacts are identified. The resulting residue-residue contact map, dubbed repulsive CSU (rCSU), is more sound in its physico-chemical justification than CSU. It also provides a clear prescription for validity of an inter-residual contact: the number of attractive atomic contacts should be larger than the number of repulsive ones — a feature that is not present in CSU. However, both of these maps do not correlate well with the experimental data on protein stretching. Thus, we propose to use rCSU together with the OV map. We find that the combined map, denoted as OV+rCSU, performs better than OV. In most situations, OV and OV+rCSU yield comparable folding properties but for some proteins rCSU provides contacts which improve folding in a substantial way. We discuss the likely residue-specificity of the rCSU contacts. Finally, we make comparisons to the recently proposed shadow contact map, which is derived from different principles.
Environmental issues and work: women with multiple chemical sensitivities.
Lipson, Juliene G; Doiron, Nathalie
Multiple chemical sensitivities (MCS) is an acquired condition in which exposure to low levels of chemicals causes symptoms in multiple organ systems. Some 12%-16% of the U.S. population has some level of chemical sensitivity, 80% of whom are women. Attempts to reduce chemical exposures leads to enormous life difficulties at home, school, and workplace. We base our article on an ethnographic study of MCS in the United States and Canada. We describe here themes related to work issues in terms of a general trajectory of becoming sick from work exposures, coping with toxic physical environments and dealing with coworkers and, when unable to continue working, applying for workers' compensation, or disability status, or both.
The possible role of contact sensitization to fragrances and preservatives in poikiloderma of civatte.
Numerous mechanisms have been postulated to play an important role in the pathogenesis of poikiloderma of Civatte (PC), including chronic exposure to ultraviolet radiation, menopause-related hormonal changes, contact hypersensitivity and genetic predisposition. Herein, we report a case of contact sensitization to fragrances and commonly used preservatives, methylchloroisothiazolinone and methylisothiazolinone, also widely known as Kathon CG, in a post-menopausal woman with PC, who denied excessive sun exposure and a family history. After abstaining from the use of her personal care products containing the documented allergens, not only the itching and burning symptoms, but also the cutaneous changes appeared to improve partially. This report underlines the possible influence of contact hypersensitivity in the pathogenesis of PC.
Saranya Khunkhet
Full Text Available Numerous mechanisms have been postulated to play an important role in the pathogenesis of poikiloderma of Civatte (PC, including chronic exposure to ultraviolet radiation, menopause-related hormonal changes, contact hypersensitivity and genetic predisposition. Herein, we report a case of contact sensitization to fragrances and commonly used preservatives, methylchloroisothiazolinone and methylisothiazolinone, also widely known as Kathon CG, in a post-menopausal woman with PC, who denied excessive sun exposure and a family history. After abstaining from the use of her personal care products containing the documented allergens, not only the itching and burning symptoms, but also the cutaneous changes appeared to improve partially. This report underlines the possible influence of contact hypersensitivity in the pathogenesis of PC.
Occupational contact sensitization in female geriatric nurses: Data of the Information Network of Departments of Dermatology (IVDK) 2005-2014.
Schubert, S; Bauer, A; Molin, S; Skudlik, C; Geier, J
Geriatric nurses (GN) have a high risk of occupational contact dermatitis (OCD), with chronic irritant contact dermatitis predominating. However, allergic contact dermatitis is an important issue as well. Little is known whether the relevant occupational allergen spectrum reported in the 1990s, including fragrances, preservatives, rubber chemicals and ingredients of surface disinfectants to be the most common sensitizers in GN, is still valid. To monitor the current allergen spectrum in GN with OCD and verify the validity of the patch test recommendations (baseline-, preservative-, ointment base-, rubber-, disinfectant, series and fragrances) in GN with suspected OCD given by the German Contact Dermatitis Research Group (DKG). Retrospective analysis of IVDK data (2005-2014) of 743 female GN with OCD, in comparison to 695 GN without OCD. GN with OCD reacted significantly more frequently to both fragrance mixes, hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC), thiuram mix, zinc diethyldithiocarbamate and mercaptobenzothiazole than GN without OCD. Reactions to MDBGN, methylchloroisothiazolinone/methylisothiazolinone and oil of turpentine occurred substantially, but not significantly more frequently among GN with OCD. The latter may be due to former use of a special alcoholic liniment in geriatric care. Among material from the patients' workplaces, tetrazepam was a frequent allergen, due to dust exposure from pill crushing. Furthermore, occupationally used protective gloves, body care products as well as surface disinfectants were often tested positively. The general allergen spectrum in GN with OCD is unchanged, so the DKG patch test recommendations are still valid. Prevention of occupational sensitization should focus on fragrance-free hygiene and body care products, usage of accelerator-free protective gloves and avoidance of drug dust exposure. © 2016 European Academy of Dermatology and Venereology.
Hall effect enhanced low-field sensitivity in a three-contact extraordinary magnetoresistance sensor
Sun, Jian
An extraordinary magnetoresistance (EMR) device with a 3-contact geometry has been fabricated and characterized. A large enhancement of the output sensitivity at low magnetic fields compared to the conventional EMR device has been found, which can be attributed to an additional influence coming from the Hall effect. Output sensitivities of 0.19 mV/T at zero-field and 0.2 mV/T at 0.01 T have been measured in the device, which is equivalent to the ones of the conventional EMR sensors with a bias of ∼0.04 T. The exceptional performance of EMR sensors in the high field region is maintained in the 3-contact device.
Perfume sensitivity in adult females. A study of contact sensitivity to a perfume mix in two groups of student nurses.
Guin, J D; Berry, V K
The incidence of contact sensitivity to a perfume mix was investigated in two groups of student nurses by questionnaire and patch testing. Twenty-nine of ninety gave a history of dermatitis on exposure to fragrances or perfumed cosmetics. Fifteen of eighty-five showed a positive patch test reaction to a perfume mix comprising 2% concentrations of eight different perfume ingredients, and twelve of the fifteen had a positive history. Chi-square analysis of the data indicates that the results of the two methods of measurements are significantly related (p < 0.0001).
Contact sensitivity to newsprint: a rare manifestation of coal tar allergy
Illchyshyn, A; Cartwright, P H; Smith, A G
Contact dermatitis due to coal tar is infrequently reported in spite of the fact that it consists of a mixture of 10,000 constituents, and is still often used to treat both eczema and psoriasis. Discusses patient with coal tar sensitivity in whom the source of exacerbation of her dermatitis is shown to be newsprint, a common product containing coal tar-derived material. 6 refs.
Structure and Properties of Hydrophobic Aggregation Hydrogel with Chemical Sensitive Switch
Jiufang Duan
Full Text Available Hydrogels with chemical sensitive switch have control release properties in special environments. A series of polyacrylamide-octadecyl methacrylate hydrogels crosslinked by N,N′-bis (acryloyl cystamine were synthesized as potential chemical sensitive system. When this hydrogel encounters dithiothreitol it can change its quality. The properties of the hydrogels were characterized by infrared spectroscopy, contact angle, and scanning electron microscopy. The water absorption of the hydrogel has the maximum value of 475%, when the content of octadecyl methacrylate is 5 wt%. The amount of weight loss was changed from 34.6% to 17.2%, as the content of octadecyl methacrylate increased from 3 wt% to 9.4 wt%. At the same time, the stress of the hydrogel decreased from 67.01% to 47.61%; the strength of the hydrogel reaches to the maximum 0.367 Mpa at 7 wt% octadecyl methacrylate. The increasing content of octadecyl methacrylate from 3 wt% to 9.4 wt% can enhance the hydrophobicity of the hydrogel; the contact angle of water to hydrogel changed from 14.10° to 19.62°. This hydrogel has the porous structure which permits loading of oils into the gel matrix. The functionalities of the hydrogel make it have more widely potential applications in chemical sensitive response materials.
Development and Utilization of an Ex Vivo Bromodeoxyuridine Local Lymph Node Assay (LLNA) Protocol for Assessing Potential Chemical Sensitizers
The murine local lymph node assay (LLNA) is widely used to identify chemicals that may cause allergic contact dermatitis. Exposure to a dermal sensitizer results in proliferation of local lymph node T cells, which has traditionally been measured by in vivo incorporation of [3H]m...
Analysis of Wetting and Contact Angle Hysteresis on Chemically Patterned Surfaces
Xu, Xianmin; Wang, Xiaoping
Wetting and contact angle hysteresis on chemically patterned surfaces in two dimensionsare analyzed from a stationary phase-field model for immiscible two phase fluids. We first study the sharp-interface limit of the model by the method of matched asymptotic expansions. We then justify the results rigorously by the γ-convergence theory for the related variational problem and study the properties of the limiting minimizers. The results also provide a clear geometric picture of the equilibrium configuration of the interface. This enables us to explicitly calculate the total surface energy for the two phase systems on chemically patterned surfaces with simple geometries, namely the two phase flow in a channel and the drop spreading. By considering the quasi-staticmotion of the interface described by the change of volume (or volume fraction), we can follow the change-of-energy landscape which also reveals the mechanism for the stick-slip motion of the interface and contact angle hysteresis on the chemically patterned surfaces. As the interface passes throughpatterned surfaces, we observe not only stick-slip of the interface and switching of the contact angles but also the hysteresis of contact point and contact angle. Furthermore, as the size of the patternde creases to zero, the stick-slip becomes weaker but the hysteresis becomes stronger in the sense that one observes either the advancing contact angle or the receding contact angle (when the interface ismoving in the opposite direction) without the switching in between. © 2011 Society for Industrial and Applied Mathematics.
Immunological, chemical and clinical aspects of exposure to mixtures of contact allergens
Bonefeld, Charlotte M.; Geisler, Carsten; Gimenéz-Arnau, Elena
relevant. In this article, we provide a general introduction to immune responses to contact allergens, and discuss the literature concerning immune responses to mixtures of allergens. According to the existing evidence, increased responses are induced following sensitization with combinations of allergens...
The Prevalence of Allergic Contact Sensitization of Practicing and Student Nurses
A Akan
Full Text Available Background: Contact dermatitis (CD is a significant problem among nurses. Although there are reports about the prevalence of CD from different parts of the world, data about its frequency in Turkey and about allergic contact sensitization among nurses is insufficient. Objective: To define the frequency and patterns of allergic contact sensitization and related symptoms in practicing and student nurses. Methods: There were 123 nurses in our hospital practicing in the in-patient clinics. All were invited to participate in the study. 69 working-in nurses and 79 student nurses participated in the study. The main reason for refusal of nurses was that they were usually having a shower daily after a hard working day and they had to postpone having a bath for 3 days if they had a patch test on their back. A ready-to-use patch test system (TRUE test® with 29 standardized test substances was applied to all of the participants. History about symptoms of CD and allergic diseases was investigated by questionnaire. Results: While 34.8% (24/69 of practicing nurses had symptoms of CD, 19% (15/79 of student nurses reported the symptoms (p=0.039. The most prevalent positive reaction was to nickel sulfate followed by thimerosal. There was no difference for positive reaction rates between practicing and student nurses. Nurses who had symptoms of CD were older than those without symptoms (p=0.003. The participants with symptoms of CD were more frequently from practicing nurses (p=0.047. Conclusion: CD is more frequent in practicing nurses than student nurses; allergic contact sensitization is not. This may be attributed to the length of occupation that is also correlated well with the length of exposure to the occupational irritants.
Screening for skin-sensitizing allergens among patients with clinically suspected allergic contact dermatitis
Zahid Shakoor
Full Text Available Objectives: To detect common skin-sensitizing agents among patients experiencing allergic contact dermatitis (ACD. Methods: This was a retrospective study of 152 patients with clinically suspected ACD who underwent patch testing in an allergy clinic at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia between January 2012 and February 2015. Of these patients, only 74 (48% patients reacted to one or more contact allergens. This group of patients included 58 (78.4% women and 16 (21.6% men (mean age: 37.8±13.8 years. Patch testing was performed using the thin-layer rapid-use epicutaneous patch test panels. Results: Nickel sulfate was the most common sensitizing agent, with 26 (35.1% patients yielding a positive result; followed by p-phenylenediamine in 17 (22.9%, butyl-tetra-phenol formaldehyde in 12 (16.2%, gold sodium thiosulfate in 10 (13.5%, and thimerosal in 6 (8.1% patients. Nickel reactivity was significantly higher among women (41.4% than among men (12.5% (p less than 0.0001. Similarly, gold reactivity among women (15.5% was also higher than among men (6.2% (p≤0.02. Conclusion: The high level of skin sensitization due to nickel, PPD, and gold in patients with ACD emphasizes the need for measures to decrease exposure to these sensitizing agents.
Two Cases of Occupational Contact Urticaria Caused by Percutaneous Sensitization to Parvalbumin
Akiyo Sano
Full Text Available Background: In recent years, it has been proposed that the primary mechanism for the development of food allergies is percutaneous sensitization. Since 2010, in Japan, the number of immediate-type wheat allergy due to hydrolyzed wheat protein has dramatically increased among those who have been using soap containing hydrolyzed wheat. This incidence supports the hypothesis that food allergens arise through percutaneous sensitization. Clinical Summary: A 25-year-old man (case 1 and an 18-year-old girl (case 2 with atopic dermatitis visited our Department because of food allergy and hand eczema. After starting their work with fish, severe itchy eczema appeared on their hands. They subsequently started to experience oral allergic symptoms, intraoral itchiness and dyspnea after eating fish. Specific IgE antibodies were detected for many fishes, and skin prick tests showed positive reactions for a variety of fishes in both cases. Furthermore, the fluorescence intensities of specific IgE antibodies against parvalbumin from various types of fish in microarray immunoassay analysis showed positive reactions. We diagnosed them as contact urticaria caused by percutaneous sensitization to parvalbumin through job-related physical contact with fish. Conclusion: The patients' histories and findings indicate the possibility of percutaneous sensitization through occupational exposure to parvalbumin, leading to food allergy.
Two Cases of Occupational Contact Urticaria Caused by Percutaneous Sensitization to Parvalbumin.
Sano, Akiyo; Yagami, Akiko; Suzuki, Kayoko; Iwata, Yohei; Kobayashi, Tsukane; Arima, Masaru; Kondo, Yasuto; Yoshikawa, Tetsushi; Matsunaga, Kayoko
In recent years, it has been proposed that the primary mechanism for the development of food allergies is percutaneous sensitization. Since 2010, in Japan, the number of immediate-type wheat allergy due to hydrolyzed wheat protein has dramatically increased among those who have been using soap containing hydrolyzed wheat. This incidence supports the hypothesis that food allergens arise through percutaneous sensitization. A 25-year-old man (case 1) and an 18-year-old girl (case 2) with atopic dermatitis visited our Department because of food allergy and hand eczema. After starting their work with fish, severe itchy eczema appeared on their hands. They subsequently started to experience oral allergic symptoms, intraoral itchiness and dyspnea after eating fish. Specific IgE antibodies were detected for many fishes, and skin prick tests showed positive reactions for a variety of fishes in both cases. Furthermore, the fluorescence intensities of specific IgE antibodies against parvalbumin from various types of fish in microarray immunoassay analysis showed positive reactions. We diagnosed them as contact urticaria caused by percutaneous sensitization to parvalbumin through job-related physical contact with fish. The patients' histories and findings indicate the possibility of percutaneous sensitization through occupational exposure to parvalbumin, leading to food allergy.
Contact sensitization to cosmetic series of allergens in a general population in Beijing.
Zhao, Jian; Li, Lin-Feng
Cosmetic allergic contact dermatitis (CACD) due to common cosmetic allergens in standard series has been extensively studied; however, the prevalence of contact allergy to other cosmetic allergens other than those in standard series is largely unknown. In this study, the frequency of contact sensitization to a European cosmetic series of allergens (Chemotechnique Diagnostics, Vellinge, Sweden) in healthy university student volunteers were detected in Beijing. Of 201 students studied, fifty-eight exhibited positive results, and 9 of them reported had cosmetics related dermatitis previously. The total positivity rate was not correlated to gender. The leading allergens were thimerosal (19.4%), shellac (3.0%), cocamidopropyl betaine (2.0%), hexamethylenetetramine (1.5%), dodecyl gallate (1.5%), hexahydro-1,3,5-tris-(2-hydroxyethyl)triazine (1.0%) and methyldibromo glutaronitrile (1.0%). The positivity rate of thimerosal patch test in men (9.8%) was lower than that of women (23.6%, P cosmetic allergens in men and women (P > 0.05, Chi square test). These results suggested that some cosmetic-related contact allergies may be missed by just testing patients with the European standard series or T.R.U.E. test system only, we recommend shellac, cocamidopropyl betaine, hexamethylenetetramine and dodecyl gallate as the additionally candidates for patch testing in patients with suspected CACD. © 2014 Wiley Periodicals, Inc.
Contact irritant responses of Aedes aegypti Using sublethal concentration and focal application of pyrethroid chemicals.
Hortance Manda
Full Text Available BACKGROUND: Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application. METHODS: Contact irritancy (escape behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin. RESULTS: Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%. CONCLUSIONS/SIGNIFICANCE: Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is
Manda, Hortance; Shah, Pankhil; Polsomboon, Suppaluck; Chareonviriyaphap, Theeraphap; Castro-Llanos, Fanny; Morrison, Amy; Burrus, Roxanne G; Grieco, John P; Achee, Nicole L
Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application. Contact irritancy (escape) behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru) using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC) of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin. Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR) resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at time of exit (by four hours) and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%. Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.
CHEMICAL VAPOUR DEPOSITION FROM A RADIATION-SENSITIVE PRECURSOR
The present invention relates in one aspect to a method of depositing a thin film on a substrate by chemical vapour deposition (CVD) from a radiation-sensitive precursor substance. The method comprises the steps of: (i) placing the substrate in a reaction chamber of a CVD system; (ii) heating...... heating pulse followed by an idle period; (iii) during at least one of the idle periods, providing a pressure pulse of precursor substance inside the reaction chamber by feeding at least one precursor substance to the reaction chamber so as to establish a reaction partial pressure for thin film deposition...... is formed. According to a further aspect, the invention relates to a chemical vapour deposition (CVD) system for depositing a thin film onto a substrate using precursor substances containing at least one radiation sensitive species....
Tribo-chemical behavior of eutectoid steel during rolling contact friction
Zhou, Y.; Cai, Z.B. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Peng, J.F. [Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China); Cao, B.B. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Jin, X.S. [Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China); Zhu, M.H., E-mail: zhuminhao@swjtu.cn [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China)
Highlights: • Tribo-chemical behavior was investigated during rolling contact friction. • Tribo-film may weaken the absorptive ability of O/C atoms on the surface. • Tribo-film is related to a low friction coefficient at rolling friction condition. - Abstract: The tribo-chemical behavior of the eutectoid steel during rolling contact friction is investigated via scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and electron probe X-ray microanalysis. The worn surface is divided into three zones: matrix zone (without friction), tribo-film zone (formed during friction) and delamination zone (tribo-film spalling). The different chemical states of atoms between those three zones and the air were investigated using the XPS analysis. The results showed that the matrix zone is composed of Fe{sub 2}O{sub 3}, FeO and metallic Fe, while the tribo-film and delamination zones only contain Fe{sub 2}O{sub 3} and FeO. Where the tribo-film is formed, the absorptive ability of O and C atoms on the top 2–3 atomic layers is probably weakened, while the exposed fresh metal in the delamination zone tends to be continuously oxidized and form tribo-film. The tribo-chemical reaction in the delamination zone is more activated than that in the other two zones. The protective nature of the tribo-film probably maintains a low friction coefficient under rolling contact friction condition.
High-throughput dietary exposure predictions for chemical migrants from food contact substances for use in chemical prioritization.
Biryol, Derya; Nicolas, Chantel I; Wambaugh, John; Phillips, Katherine; Isaacs, Kristin
Under the ExpoCast program, United States Environmental Protection Agency (EPA) researchers have developed a high-throughput (HT) framework for estimating aggregate exposures to chemicals from multiple pathways to support rapid prioritization of chemicals. Here, we present methods to estimate HT exposures to chemicals migrating into food from food contact substances (FCS). These methods consisted of combining an empirical model of chemical migration with estimates of daily population food intakes derived from food diaries from the National Health and Nutrition Examination Survey (NHANES). A linear regression model for migration at equilibrium was developed by fitting available migration measurements as a function of temperature, food type (i.e., fatty, aqueous, acidic, alcoholic), initial chemical concentration in the FCS (C 0 ) and chemical properties. The most predictive variables in the resulting model were C 0 , molecular weight, log K ow , and food type (R 2 =0.71, pchemicals identified via publicly-available data sources as being present in polymer FCSs were predicted for 12 food groups (combinations of 3 storage temperatures and food type). The model was parameterized with screening-level estimates of C 0 based on the functional role of chemicals in FCS. By combining these concentrations with daily intakes for food groups derived from NHANES, population ingestion exposures of chemical in mg/kg-bodyweight/day (mg/kg-BW/day) were estimated. Calibrated aggregate exposures were estimated for 1931 chemicals by fitting HT FCS and consumer product exposures to exposures inferred from NHANES biomonitoring (R 2 =0.61, pchemicals), they can provide critical refinement to aggregate exposure predictions used in risk-based chemical priority-setting. Published by Elsevier Ltd.
Contact dermatitis caused by tulips: identification of contact sensitizers in tulip workers of Kashmir Valley in North India.
Hassan, Iffat; Rasool, Farhan; Akhtar, Saniya; Kamili, Afifa; Rather, Parvaiz; Kanth, Raihana; Bhat, Yasmeen; Rather, Shagufta; Mubashir, Syed; Yaseen, Atiya; Bashir, Safia
Tulip, belonging to the genus Tulipa and family Liliaceae, is a spring-blooming perennial that grows from bulbs. Owing to manual handling, contact dermatitis can occur in professionals at any stage of the growth cycle of the tulip plant. To determine the clinical pattern of contact dermatitis resulting from tulip plant cultivation, and to assess contact allergy in workers coming into contact with this plant. One hundred and sixty-four tulip workers were screened, and 48 patients with suspected contact dermatitis were patch tested with 39 allergens, including haptens from the Indian baseline series, a plant series, and extracts from different parts of the tulip plant. Thirty-nine positive patch test reactions were observed in 21 patients. Seventeen patients showed positive reactions to either α-methylene-γ-butyrolactone or to tulip plant extract. Clinical relevance was observed for 13 of 17 positive patch test reactions. Contact dermatitis is an important health hazard in workers dealing with tulip bulbs. Further studies to identify and isolate other possible tulip allergens, and to quantify the amounts of allergens in different parts of the tulip plant, are recommended. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Identifying populations sensitive to environmental chemicals by simulating toxicokinetic variability.
Ring, Caroline L; Pearce, Robert G; Setzer, R Woodrow; Wetmore, Barbara A; Wambaugh, John F
physiological parameters for a virtual population. For risk-based prioritization of chemicals, predicted bioactive equivalent doses were compared to demographic-specific inferences of exposure rates that were based on NHANES urinary analyte biomonitoring data. The inclusion of NHANES-derived inter-individual variability decreased predicted bioactive equivalent doses by 12% on average for the total population when compared to previous methods. However, for some combinations of chemical and demographic groups the margin was reduced by as much as three quarters. This TK modeling framework allows targeted risk prioritization of chemicals for demographic groups of interest, including potentially sensitive life stages and subpopulations. Published by Elsevier Ltd.
Hand eczema: Correlation of morphologic patterns, atopy, contact sensitization and disease severity
Sanjeev Handa
Full Text Available Background: Hand eczema is a common distressing condition aggravated by a number of endogenous and exogenous factors. Various morphological forms of hand eczema have been described, but categorization into one of them is not always possible. Aims: To study the morphological patterns of hand eczema, relationship of atopy with hand eczema, and the implications of contact sensitization with respect to severity and diagnosis of hand eczema. Methods: Hundred consecutive patients of hand eczema attending the contact dermatitis clinic of the institute were recruited over a two year period from 2004-05. Objective assessment was done using hand eczema severity index (HECSI and all the patients were patch tested using Indian standard series. Results: Unspecified type of hand eczema with no definite morphologic picture was seen in 62% followed by pompholyx in 14%. Hand eczema severity was not found to be statistically associated with age, sex, and atopic status of the patient. Positive patch test to one or more allergen was present in 65% of patients. The most common allergens were potassium dichromate (25%, fragrance mix (16%, nickel sulphate (14%, and PPD (13%. There was no significant correlation between patch test positivity and hand eczema severity or atopic status of the patient. Among the morphological patterns pompholyx was strongly associated with an atopic status (P=0.004. Conclusions: Hand eczema was seen twice more commonly in men. Atopic and non-atopic patients of hand eczema had no difference in the severity of disease. Contact sensitivity to different allergens did not correlate with increased eczema severity.
Evaluation of touch-sensitive screen tablet terminal button size and spacing accounting for effect of fingertip contact angle.
Nishimura, T; Doi, K; Fujimoto, H
Touch-sensitive screen terminals enabling intuitive operation are used as input interfaces in a wide range of fields. Tablet terminals are one of the most common devices with a touch-sensitive screen. They have a feature of good portability, enabling use under various conditions. On the other hand, they require a GUI designed to prevent decrease of usability under various conditions. For example, the angle of fingertip contact with the display changes according to finger posture during operation and how the case is held. When a human fingertip makes contact with an object, the contact area between the fingertip and contact object increases or decreases as the contact angle changes. A touch-sensitive screen detects positions using the change in capacitance of the area touched by the fingertip; hence, differences in contact area between the touch-sensitive screen and fingertip resulting from different forefinger angles during operation could possibly affect operability. However, this effect has never been studied. We therefore conducted an experiment to investigate the relationship between size/spacing and operability, while taking the effect of fingertip contact angle into account. As a result, we have been able to specify the button size and spacing conditions that enable accurate and fast operation regardless of the forefinger contact angle.
Novel approach for classifying chemicals according to skin sensitizing potency by non-radioisotopic modification of the local lymph node assay.
Takeyoshi, Masahiro; Iida, Kenji; Shiraishi, Keiji; Hoshuyama, Satsuki
The murine local lymph node assay (LLNA) is currently recognized as a stand-alone sensitization test for determining the sensitizing potential of chemicals, and it has the advantage of yielding a quantitative endpoint that can be used to predict the sensitization potency of chemicals. The EC3 has been proposed as a parameter for classifying chemicals according to the sensitization potency. We previously developed a non-radioisotopic endpoint for the LLNA based on 5-bromo-2'-deoxyuridine (BrdU) incorporation (non-RI LLNA), and we are proposing a new procedure to predict the sensitization potency of chemicals based on comparisons with known human contact allergens. Nine chemicals (i.e. diphencyclopropenone, p-phenylenediamine, glutaraldehyde, cinnamicaldehyde, citral, eugenol, isopropyl myristate, propyleneglycol and hexane) categorized as human contact allergen classes 1-5 were tested by the non-RI LLNA with the following reference allergens: 2,4-dinitrochlorobenzene (DNCB) as a class 1 human contact allergen, isoeugenol as a class 2 human contact allergen and alpha-hexylcinnamic aldehyde (HCA) as a class 3 human contact allergen. Consequently, nine test chemicals were almost assigned to their correct allergen class. The results suggested that the new procedure for non-RI LLNA can provide correct sensitization potency data. Sensitization potency data are useful for evaluating the sensitization risk to humans of exposure to new chemical products. Accordingly, this approach would be an effective modification of LLNA with regard to its experimental design. Moreover, this procedure can be applied also to the standard LLNA with radioisotopes and to other modifications of the LLNA. Copyright 2005 John Wiley & Sons, Ltd.
Cellular dynamics in the draining lymph nodes during sensitization and elicitation phases of contact hypersensitivity
Larsen, Jeppe Madura; Geisler, Carsten; Nielsen, Martin Weiss
BACKGROUND: The different role of various immunological effector cells in contact hypersensitivity (CHS) is receiving increased attention. During the past decade, the involvement of different cell types in CHS has been investigated by the use of antibody-induced depletion of specific subtypes...... of immunological cells and by studying knockout mice lacking one or more of these immunological cell populations. OBJECTIVES: To develop a method for studying the collective cellular dynamics of immune cells in the draining lymph nodes during CHS in intact animals. PATIENTS/METHODS: Mice were sensitized and....../or challenged with 2,4-dinitrofluorobenzene or oxazolone. Using multi-parameter flow cytometry we determined the proliferation, activation state, and absolute number of helper T cells, cytotoxic T cells, B cells, and natural killer cells in the draining lymph nodes. RESULTS: The presented method can be applied...
Chemical control of electrical contact to sp² carbon atoms.
Carbon-based nanostructures are attracting tremendous interest as components in ultrafast electronics and optoelectronics. The electrical interfaces to these structures play a crucial role for the electron transport, but the lack of control at the atomic scale can hamper device functionality and integration into operating circuitry. Here we study a prototype carbon-based molecular junction consisting of a single C60 molecule and probe how the electric current through the junction depends on the chemical nature of the foremost electrode atom in contact with the molecule. We find that the efficiency of charge injection to a C60 molecule varies substantially for the considered metallic species, and demonstrate that the relative strength of the metal-C bond can be extracted from our transport measurements. Our study further suggests that a single-C60 junction is a basic model to explore the properties of electrical contacts to meso- and macroscopic sp(2) carbon structures.
Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces.
Chen, Szu-Ying; Kaufman, Yair; Schrader, Alex M; Seo, Dongjin; Lee, Dong Woog; Page, Steven H; Koenig, Peter H; Isaacs, Sandra; Gizaw, Yonas; Israelachvili, Jacob N
Measuring truly equilibrium adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing-receding contact angles and loading-unloading adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±V, focusing on the thermodynamic limit of ±V → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) adhesion energies and contact angles suitable for both (i) dynamic adhesion measurements using the classic Johnson-Kendall-Roberts (JKR, 1971) theory of "contact mechanics" and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V contact angles converged toward the same theoretical (thermodynamic) values as V → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic theories of adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the
Sensitivity of juvenile striped bass to chemicals used in aquaculture
Bills, Terry D.; Marking, Leif L.; Howe, George E.
Efforts to restore anadromous striped bass (Morone saxatilis) populations by the U.S. Fish and Wildlife Service and other agencies over the past 20 years have concentrated on hatchery culture to supplement dwindling natural reproduction. Adult fish captured for artificial spawning are stressed by handling and crowding in rearing ponds and are often exposed to therapeutants, anesthetics, disinfectants, and herbicides used in fish culture. We determined the toxicity of 17 fishery chemicals (chloramine-T, erythromycin, formalin, Hyamine 3500, Roccal, malachite green, sulfamerazine, benzocaine, etomidate, Finquel (MS-222) , metomidate, quinaldine sulfate, chlorine, potassium permanganate, Aquazine, copper sulfate, and Rodeo) to striped bass fry (average weight = 1 g) in reconstituted water (total hardness 40 mg/L) at 12 degree C. The 96-h LC50's (concentration calculated to produce 50% mortality in a population) ranged from 0.129 mg/L for malachite green to 340 mg/L for erythromycin. We also determined the effects of selected levels of water temperature, hardness, and pH on the toxicity of chloramine-T, formalin, malachite green, and Roccal. There were no differences in toxicity for any of the chemicals at any water quality variable tested except for chloramine-T, which was about 25 times more toxic in soft, acid water than in soft, alkaline water. Our data show that the striped bass is as sensitive to fishery chemicals as rainbow trout (Oncorhynchus mykiss), but is generally less resistant than bluegill (Lepomis macrochirus) and channel catfish (Ictalurus punctatus).
125I-Fibrin deposition in contact sensitivity reactions in the mouse. Sensitivity of the assay for quantitating reactions after active or passive sensitization
Mekori, Y.A.; Dvorak, H.F.; Galli, S.J.
The clotting associated with delayed hypersensitivity (DH) responses in the mouse by sensitizing the animals to the contactant oxazolone (Ox), and then administering 125 I-guinea pig fibrinogen i.v. 10 to 30 min before antigen challenge 5 days later. Early (4 to 8 hr) contact sensitivity (CS) responses in immunized mice were barely detectable by three conventional measures of CS, but the total 125 I-cpm in ears challenged with hapten was 3.6 to 4.5 x that in control ears challenged with vehicle alone; moreover, the amount of urea-insoluble cpm (cross-linked 125 I-fibrin-associated cpm) in the reactions to Ox was 6.5-fold to 8.2-fold that present in the control reactions. In 24 hr reactions that were near peak intensity by measurements of ear swelling, ear weight ratios, and ratios of 125 I-5-iodo-2-deoxyuridine-labeled leukocyte infiltration, the cpm in antigen-challenged ears exceeded that in control ears by 13-fold to 53-fold. In addition, antigen-challenged ears contained 27 to 300 x the urea-insoluble cpm present in control ears. 125 I-Fibrin deposition was not a specific characteristic of CS reactions, because a small amount of urea-insoluble reactivity was also detected in some reactions to Ox in native mice. Nevertheless, the assay was exquisitely sensitive and readily detected quantitative differences between the immunologically specific and nonspecific reactions at very early intervals after challenge or with suboptimal doses of antigen
Transient receptor potential ankyrin 1 activation enhances hapten sensitization in a T-helper type 2-driven fluorescein isothiocyanate-induced contact hypersensitivity mouse model
Shiba, Takahiro; Tamai, Takuma; Sahara, Yurina; Kurohane, Kohta; Watanabe, Tatsuo; Imai, Yasuyuki
Some chemicals contribute to the development of allergies by increasing the immunogenicity of other allergens. We have demonstrated that several phthalate esters, including dibutyl phthalate (DBP), enhance skin sensitization to fluorescein isothiocyanate (FITC) in a mouse contact hypersensitivity model, in which the T-helper type 2 (Th2) response is essential. On the other hand, some phthalate esters were found to activate transient receptor potential ankyrin 1 (TRPA1) cation channels on sensory neurons. We then found a positive correlation between the enhancing effects of several types of phthalate esters on skin sensitization to FITC and their ability to activate TRPA1. Here we examined the involvement of TRPA1 in sensitization to FITC by using TRPA1 agonists other than phthalate esters. During skin sensitization to FITC, the TRPA1 agonists (menthol, carvacrol, cinnamaldehyde and DBP) augmented the ear-swelling response as well as trafficking of FITC-presenting dendritic cells to draining lymph nodes. We confirmed that these TRPA1 agonists induced calcium influx into TRPA1-expressing Chinese hamster ovary (CHO) cells. We also found that TRPA1 antagonist HC-030031 inhibited DBP-induced calcium influx into TRPA1-expressing CHO cells. After pretreatment with this antagonist upon skin sensitization to FITC, the enhancing effect of DBP on sensitization was suppressed. These results suggest that TRPA1 activation will become a useful marker to find chemicals that facilitate sensitization in combination with other immunogenic haptens. -- Highlights: â–º Role of TRPA1 activation was revealed in a mouse model of skin sensitization to FITC. â–º TRPA1 agonists enhanced skin sensitization as well as dendritic cell trafficking. â–º Dibutyl phthalate (DBP) has been shown to enhance skin sensitization to FITC. â–º TRPA1 activation by DBP was inhibited by a selective antagonist, HC-030031. â–º HC-030031 inhibited the enhancing effect of DBP on skin sensitization to FITC.
Shiba, Takahiro; Tamai, Takuma; Sahara, Yurina; Kurohane, Kohta [Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, 52�1 Yada, Suruga-ku, Shizuoka City, Shizuoka 422�8526 (Japan); Watanabe, Tatsuo [Laboratory of Food Chemistry, School of Food and Nutritional Sciences, University of Shizuoka, 52�1 Yada, Suruga-ku, Shizuoka City, Shizuoka 422�8526 (Japan); Imai, Yasuyuki, E-mail: imai@u-shizuoka-ken.ac.jp [Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, 52�1 Yada, Suruga-ku, Shizuoka City, Shizuoka 422�8526 (Japan)
Stick-Slip Motion of Moving Contact Line on Chemically Patterned Surfaces
Wu, Congmin; Lei, Siulong; Qian, Tiezheng; Wang, Xiaoping
Based on our continuum hydrodynamic model for immiscible two-phase flows at solid surfaces, the stick-slip motion has been predicted for moving contact line at chemically patterned surfaces [Wang et al., J. Fluid Mech., 605 (2008), pp. 59-78]. In this paper we show that the continuum predictions can be quantitatively verified by molecular dynamics (MD) simulations. Our MD simulations are carried out for two immiscible Lennard-Jones fluids confined by two planar solid walls in Poiseuille flow geometry. In particular, one solid surface is chemically patterned with alternating stripes. For comparison, the continuum model is numerically solved using material parameters directly measured in MD simulations. From oscillatory fluid-fluid interface to intermittent stick-slip motion of moving contact line, we have quantitative agreement between the continuum and MD results. This agreement is attributed to the accurate description down to molecular scale by the generalized Navier boundary condition in our continuum model. Numerical results are also presented for the relaxational dynamics of fluid-fluid interface, in agreement with a theoretical analysis based on the Onsager principle of minimum energy dissipation. © 2010 Global-Science Press.
Broad spectrum antibiotic enrofloxacin modulates contact sensitivity through gut microbiota in a murine model.
Strzępa, Anna; Majewska-Szczepanik, Monika; Lobo, Francis M; Wen, Li; Szczepanik, Marian
Medical advances in the field of infection therapy have led to an increasing use of antibiotics, which, apart from eliminating pathogens, also partially eliminate naturally existing commensal bacteria. It has become increasingly clear that less exposure to microbiota early in life may contribute to the observed rise in "immune-mediated" diseases, including autoimmunity and allergy. We sought to test whether the change of gut microbiota with the broad spectrum antibiotic enrofloxacin will modulate contact sensitivity (CS) in mice. Natural gut microbiota were modified by oral treatment with enrofloxacin prior to sensitization with trinitrophenyl chloride followed by CS testing. Finally, adoptive cell transfers were performed to characterize the regulatory cells that are induced by microbiota modification. Oral treatment with enrofloxacin suppresses CS and production of anti-trinitrophenyl chloride IgG1 antibodies. Adoptive transfer experiments show that antibiotic administration favors induction of regulatory cells that suppress CS. Flow cytometry and adoptive transfer of purified cells show that antibiotic-induced suppression of CS is mediated by TCR αβ + CD4 + CD25 + FoxP3 + Treg, CD19 + B220 + CD5 + IL-10 + , IL-10 + Tr1, and IL-10 + TCR γδ + cells. Treatment with the antibiotic induces dysbiosis characterized by increased proportion of Clostridium coccoides (cluster XIVa), C coccoides-Eubacterium rectale (cluster XIVab), Bacteroidetes, and Bifidobacterium spp, but decreased segmented filamentous bacteria. Transfer of antibiotic-modified gut microbiota inhibits CS, but this response can be restored through oral transfer of control gut bacteria to antibiotic-treated animals. Oral treatment with a broad spectrum antibiotic modifies gut microbiota composition and promotes anti-inflammatory response, suggesting that manipulation of gut microbiota can be a powerful tool to modulate the course of CS. Copyright © 2017 American Academy of Allergy, Asthma & Immunology
TiO{sub 2} films obtained by microwave-activated chemical-bath deposition used to improve TiO{sub 2}-conducting glass contact
Zumeta, I.; Gonzalez, B. [Institute for Material Science and Technology, University of Havana, Colina Universitaria, Ciudad Habana 10 400 (Cuba); Ayllon, J.A.; Domenech, X. [Chemistry Department, Autonomous University of Barcelona, 08290 Cerdanyola del Valles (Spain); Vigil, E. [Institute for Material Science and Technology, University of Havana, Colina Universitaria, Ciudad Habana 10 400 (Cuba); Physics Faculty, University of Havana, Colina Universitaria, Ciudad Habana 10 400 (Cuba)
In traditional solar cells, metal-semiconductor contacts used to extract photogenerated carriers are very important. In dye-sensitized solar cells (DSSC) not much attention has been given to contact between the TiO{sub 2} and the transparent conducting glass (TCO), which is used instead of a metal contact to extract electrons. TiO{sub 2} layers obtained by microwave-activated chemical-bath deposition (MW-CBD) are proposed to improve TiO{sub 2} contact to conducting glass. Spectra of incident photon to current conversion efficiency (IPCE) are obtained for two-photoelectrode TiO{sub 2} photoelectrochemical cells. IPCE spectra show higher values when TiO{sub 2} double layer photoelectrodes are used. In these, the first layer or contacting layer is made by MW-CBD. Best results are obtained for double layer photoelectrodes on FTO (SnO{sub 2}:F) as conducting oxide substrate. Modeling of IPCE spectra reveals the importance of electrical contact and electron extraction rate at the TiO{sub 2}/TCO interface. (author)
Aqueous media treatment and decontamination of hazardous chemical and biological substances by contact plasma
Pivovarov, A.; Kravchenko, A.; Kublanovsky, V.
Usage of non-equilibrium contact plasma for processes of decontamination and neutralization in conditions of manifestation of chemical, biological and radiation terrorism takes on special significance due to portability of equipment and its mobility in places where toxic liquid media hazardous for people's health are located. Processes of decontamination of aqueous media, seminated with pathogenic microorganisms and viruses, treatment of water containing toxic heavy metals, cyanides, surface-active substances, and heavy radioactive elements, are investigated. Examples of activation processes in infected water and toxic aqueous solutions present convincing evidence of the way, how new quality technological approach for achievement of high enough degree of the said media treatment is used in each specific case. Among new properties of water activated as a result of action of non-equilibrium contact plasma, it is necessary to mention presence of cluster structure, confirmed by well-known spectral and physical-chemical methods, presence of peroxide compounds, active particles and radicals. Anti-microbial activity which is displayed under action of plasma in aqueous media (chemically pure water, drinking water, aqueous solutions of sodium chloride, potassium iodide, as well as other inorganic compounds) towards wide range of pathogenic and conventionally pathogenic microorganisms allows use them as reliable, accessible and low-cost preparations for increasing the degree of safety of food products. Combination of such processes with known methods of filtration and ultra-filtration gives an efficient and available complex capable of withstanding any threats, which may arise for population and living organisms. Present-day level of machine-building, electrical engineering, and electronics allows predict creation of industrial plasma installations, adapted to conditions of various terrorist threats, with minimized power consumption and optimized technological parameters
Pivovarov, A; Kravchenko, A [Ukrainian State University of Chemical Engineering, Dnepropetrovsk (Ukraine); Kublanovsky, V [V. I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Science, Kiev (Ukraine)
Chemosensory perception, symptoms and autonomic responses during chemical exposure in multiple chemical sensitivity
Andersson, Linus; Claeson, Anna Sara; Dantoft, Thomas Meinertz
Purpose: Multiple chemical sensitivity (MCS) is a prevalent medically unexplained symptom characterized by symptom reactions to everyday chemical exposure below hygienic thresholds. The aim of this study was to investigate the expressions of hyper-reactivity in MCS during whole-body exposure to low...... concentrations of the odorant n-butanol. Methods: We exposed 18 participants with MCS and 18 non-ill controls to a low concentration of the odorant n-butanol using an exposure chamber. The first 10 min constituted blank exposure, after which the n-butanol concentration increased and reached a plateau at 11.5 mg....../m3. Results: MCS participants, compared with controls, reported greater perceived odor intensities, more unpleasantness to the exposure and increasing symptoms over time. MCS participants also expressed higher pulse rate and lower pulse rate variability than controls did. No group differences were...
Wet-Chemical Preparation of Silicon Tunnel Oxides for Transparent Passivated Contacts in Crystalline Silicon Solar Cells.
Köhler, Malte; Pomaska, Manuel; Lentz, Florian; Finger, Friedhelm; Rau, Uwe; Ding, Kaining
Transparent passivated contacts (TPCs) using a wide band gap microcrystalline silicon carbide (μc-SiC:H(n)), silicon tunnel oxide (SiO 2 ) stack are an alternative to amorphous silicon-based contacts for the front side of silicon heterojunction solar cells. In a systematic study of the μc-SiC:H(n)/SiO 2 /c-Si contact, we investigated selected wet-chemical oxidation methods for the formation of ultrathin SiO 2 , in order to passivate the silicon surface while ensuring a low contact resistivity. By tuning the SiO 2 properties, implied open-circuit voltages of 714 mV and contact resistivities of 32 mΩ cm 2 were achieved using μc-SiC:H(n)/SiO 2 /c-Si as transparent passivated contacts.
Comparison of the sensitivities of the Buehler test and the guinea pig maximization test for predictive testing of contact allergy
Frankild, S; Vølund, A; Wahlberg, J E
International test guidelines, such as the Organisation for Economic Cooperation and Development (OECD) guideline #406, recommend 2 guinea pig methods for testing of the contact allergenic potential of chemicals: the Guinea Pig Maximization Test (GPMT) and the Buehler test. Previous comparisons...
Toxicity testing and chemical analyses of recycled fibre-based paper for food contact
Binderup, Mona-Lise; Pedersen, Gitte Alsing; Vinggaard, Anne
of different qualities as food-contact materials and to Perform a preliminary evaluation of their suitability from a safety point of view, and, second, to evaluate the use of different in vitro toxicity tests for screening of paper and board. Paper produced from three different categories of recycled fibres (B...... of the paper products were extracted with either 99% ethanol or water. Potential migrants in the extracts were identified and semiquantified by GC-1R-MS or GC-HRMS. In parallel to the chemical analyses, a battery of four different in vitro toxicity tests with different endpoints were applied to the same...... was less cytotoxic than the extracts prepared from paper made from recycled fibres, and extracts prepared from C was the most cytotoxic. None of the extracts showed mutagenic activity No conclusion about the oestrogenic activity could be made, because all extracts were cytotoxic to the test organism (yeast...
Effects of gamma irradiation on food contact polyethylene, polypropylene and polystyrene: additives and other chemicals
Kawamura, Yoko; Sayama, Kayo; Yamada, Takashi
The effects of gamma irradiation on additives, oligomers, and other chemicals in food contact polyethylene, polypropylene and polystyrene were investigated. Polyethylene and polypropylene products contained several antioxidants, lubricants and plasticizers. After gamma irradiation, the contents of all the antioxidants significantly decreased. Irgafos 168 disappeared the fastest. Lubricants and plasticizers decreased to some extent or not at all. 2,4-Di-tert-butylphenol was detected not only after irradiation but also before irradiation, and 1,3-di-tert-butylbenzene and 2,6-di-tert-butyl-1,4-benzoquinone were detected only after irradiation. They were presumed to be degradation products of the irradiation, though the former should be also a degradation product of the manufacturing process. On the other hand, the polystyrene products contained styrene dimers and trimers and their contents did not change after the gamma irradiation. (author)
Treatment of high-salinity chemical wastewater by indigenous bacteria--bioaugmented contact oxidation.
Li, Qiang; Wang, Mengdi; Feng, Jun; Zhang, Wei; Wang, Yuanyuan; Gu, Yanyan; Song, Cunjiang; Wang, Shufang
A 90 m(3) biological contact oxidation system in chemical factory was bioaugmented with three strains of indigenous salt-tolerant bacteria. These three strains were screened from contaminative soil in situ. Their activity of growth and degradation was investigated with lab-scale experiments. Their salt-tolerant mechanism was confirmed to be compatible-solutes strategy for moderately halophilic bacteria, with amino acid and betaine playing important roles. The running conditions of the system were recorded for 150 days. The indigenous bacteria had such high suitability that the reactor got steady rapidly and the removal of COD maintained above 90%. It was introduced that biofilm fragments in sedimentation tank were inversely flowed to each reaction tank, and quantitative PCR demonstrated that this process could successfully maintain the bacterial abundance in the reaction tanks. In addition, the T-RFLP revealed that bioaugmented strains dominated over others in the biofilm. Copyright © 2013 Elsevier Ltd. All rights reserved.
Sensitivity of men and women to effect of chemical factors
Aliyev, V.A.
The activity of enzymes performing energy metabolism and electron transport in the respiratory chain and anabolism and catabolism processes in cells of the blood system of men and women petroleum processing workers is described and discussed. Enzymic activity was studied by cytochemical methods. Subjects included basic petroleum processing device operators (96 women and 74 men ranging in age from 19-30 years with work experience ranging from 4 months to 10 years). The control group included 133 persons of corresponding age-sex groups who were not involved in petroleum processing work. The cytoenzymic studies refuted the assumption that women workers are more sensitive than men workers to the effect of toxic substances. On the whole, the men in the study were found to be less resistant to the effect of chemical factors encountered in petroleum processing work. It was assumed that specific features of functioning of the female body (menstruation, pregnancy and birth), causing stress and reconstruction of homeostasis systems, promoted improvement of adaptational mechanisms in the process of evolution, which mechanisms were coded in the gene pool. It is speculated that sexual differences may cause differences in cell metabolism. 12 refs.
Rate and State Friction Relation for Nanoscale Contacts: Thermally Activated Prandtl-Tomlinson Model with Chemical Aging
Tian, Kaiwen; Goldsby, David L.; Carpick, Robert W.
Rate and state friction (RSF) laws are widely used empirical relationships that describe macroscale to microscale frictional behavior. They entail a linear combination of the direct effect (the increase of friction with sliding velocity due to the reduced influence of thermal excitations) and the evolution effect (the change in friction with changes in contact "state," such as the real contact area or the degree of interfacial chemical bonds). Recent atomic force microscope (AFM) experiments and simulations found that nanoscale single-asperity amorphous silica-silica contacts exhibit logarithmic aging (increasing friction with time) over several decades of contact time, due to the formation of interfacial chemical bonds. Here we establish a physically based RSF relation for such contacts by combining the thermally activated Prandtl-Tomlinson (PTT) model with an evolution effect based on the physics of chemical aging. This thermally activated Prandtl-Tomlinson model with chemical aging (PTTCA), like the PTT model, uses the loading point velocity for describing the direct effect, not the tip velocity (as in conventional RSF laws). Also, in the PTTCA model, the combination of the evolution and direct effects may be nonlinear. We present AFM data consistent with the PTTCA model whereby in aging tests, for a given hold time, static friction increases with the logarithm of the loading point velocity. Kinetic friction also increases with the logarithm of the loading point velocity at sufficiently high velocities, but at a different increasing rate. The discrepancy between the rates of increase of static and kinetic friction with velocity arises from the fact that appreciable aging during static contact changes the energy landscape. Our approach extends the PTT model, originally used for crystalline substrates, to amorphous materials. It also establishes how conventional RSF laws can be modified for nanoscale single-asperity contacts to provide a physically based friction
Exploring the sensitivity of the zone of inhibition test for leachable biocides from paper and board food contact materials, and improvements thereof.
Castle, L; Kelly, J; Jickells, S M; Johns, S M; Mountfort, K A
The zone of inhibition method to test the release of biocides from paper and board food contact materials was evaluated. The method tests the paper by placing a small specimen directly onto culture plates of Bacillus subtilis and Aspergillus niger. The principle is that any extractable biocide will diffuse from the paper into the surrounding nutrient medium and so inhibit growth of the microorganism in the vicinity. The test was found to have insufficient sensitivity for assuring food safety, where detection limits for migration at or below the mg l(-1) (parts per million) level are needed. Also, the test does not mimic the actual or foreseeable conditions of use since most paper/board materials are not intended for direct contact with an aqueous medium for up to 3 days at 30°C (B. subtilis) or 25°C (A. niger), which are the incubation conditions used. The sensitivity of the test was increased approximately 100-fold by preparing a concentrated extract of the paper to be tested and applying this extract to the assay via a blank paper carrier. This was done using methanol as a good solvent for most biocides, as a proof of principle. Other solvents or food simulants could be used to mimic the conditions of use intended for the particular paper/board samples under examination, e.g. contact with dry, fatty, aqueous or acidic foods, hot or cold. Twenty-four plain (unconverted) paper and board samples and 100 food packaging samples were evaluated using the modified procedure. The results revealed that the method has been developed to the stage where background cytotoxic action of normal paper constituents gives a weak response. Unlike the original method, therefore, the modified method with its improved sensitivity and the facility to link with the intended food contact conditions may be considered a suitable bioassay screening test to complement chemical analysis of paper/board for composition and migration.
Self-powered, ultra-sensitive, flexible tactile sensors based on contact electrification
Wang, Zhong Lin; Zhu, Guang
A tactile sensor for sensing touch from a human finger includes a triboelectric layer and includes a material that becomes electrically charged after being in contact with the finger. The first side of a first conductive layer is in contact with the second side of triboelectric layer. The first side of a dielectric layer is in contact with the first conductive layer and the second side of the dielectric layer is in contact with a second conductive layer. When the triboelectric layer becomes electrically charged after being in contact with the finger, the first conductive layer and the second conductive layer are subjected to an electric field, which has a first field strength at the first conductive layer and a second field strength, different from the first field strength, at the second conductive layer. A plurality of tactile sensors can be arranged as a keyboard.
Allergological and Toxicological Aspects in a Multiple Chemical Sensitivity Cohort
Pigatto, Paolo D.; Minoia, Claudio; Ronchi, Anna; Brambilla, Lucia; Ferrucci, Silvia M.; Spadari, Francesco; Passoni, Manuela; Somalvico, Francesco; Bombeccari, Gian Paolo
Background. Multiple chemical sensitivity (MCS) is a chronic condition characterized by an exaggerated response to toxicants. We ascertained the prevalence of allergy to metals and toxicological aspects in MCS patients. Methods. We conducted a retrospective review of medical records of 41 patients with MCS. We performed patch testing (n = 21) for dental series and did lymphocyte transformation test (n = 18) for metals. We measured mercury in samples of blood (n = 19), urine (n = 19), saliva (n = 20), and scalp hair (n = 17) to investigate the association between mercury levels and cases of MCS. Results. The prevalence of metal immune hypersensitivity in a subset of 26 patients was 92.3 percent. Elevations of mercury occurred in 81.2 percent (26 of 32). The mean (±SD) in blood concentrations of mercury was 7.6 ± 13.6 μg/L; mean in urine was 1.9 ± 2.5 μg/L; mean in scalp hair was 2.2 ± 2.5 μg/g; mean in saliva was 38.1 ± 52.1 μg/L. Subgroup analyses showed that elevation of mercury levels in biological matrices were associated with mercury amalgams in patients with MCS (22 patients), compared with controls (8 patients) (odds ratio 11 : 95 percent confidence interval 1.5 to 81.6; P = 0.023). Conclusions. Our data show an increased prevalence of metal allergy and elevation of mercury levels in bioindicators among patients with MCS. PMID:24367721
ER-mitochondria contacts control surface glycan expression and sensitivity to killer lymphocytes in glioma stem-like cells.
Bassoy, Esen Yonca; Kasahara, Atsuko; Chiusolo, Valentina; Jacquemin, Guillaume; Boydell, Emma; Zamorano, Sebastian; Riccadonna, Cristina; Pellegatta, Serena; Hulo, Nicolas; Dutoit, Valérie; Derouazi, Madiha; Dietrich, Pierre Yves; Walker, Paul R; Martinvalet, Denis
Glioblastoma is a highly heterogeneous aggressive primary brain tumor, with the glioma stem-like cells (GSC) being more sensitive to cytotoxic lymphocyte-mediated killing than glioma differentiated cells (GDC). However, the mechanism behind this higher sensitivity is unclear. Here, we found that the mitochondrial morphology of GSCs modulates the ER-mitochondria contacts that regulate the surface expression of sialylated glycans and their recognition by cytotoxic T lymphocytes and natural killer cells. GSCs displayed diminished ER-mitochondria contacts compared to GDCs. Forced ER-mitochondria contacts in GSCs increased their cell surface expression of sialylated glycans and reduced their susceptibility to cytotoxic lymphocytes. Therefore, mitochondrial morphology and dynamism dictate the ER-mitochondria contacts in order to regulate the surface expression of certain glycans and thus play a role in GSC recognition and elimination by immune effector cells. Targeting the mitochondrial morphology, dynamism, and contacts with the ER could be an innovative strategy to deplete the cancer stem cell compartment to successfully treat glioblastoma. © 2017 The Authors.
Recent trends in epidemiology, sensitization and legal requirements of selected relevant contact allergens
Schwensen, Jakob F; Bregnbak, David; Johansen, Jeanne Duus
the last 5 years, a comprehensive review of methylisothiazolinone, chromium, cobalt, rubber accelerators and fragrance ingredients were conducted. Of each allergen we discuss in detail the temporal trend of prevalence, source of exposure, clinical manifestation of allergic contact dermatitis...
Non-allergic cutaneous reactions in airborne chemical sensitivity--a population based study
Berg, Nikolaj Drimer; Linneberg, Allan; Thyssen, Jacob Pontoppidan
the relationship between cutaneous reactions from patch testing and self-reported severity of chemical sensitivity to common airborne chemicals. A total of 3460 individuals participating in a general health examination, Health 2006, were patch tested with allergens from the European standard series and screened...... for chemical sensitivity with a standardised questionnaire dividing the participants into four severity groups of chemical sensitivity. Both allergic and non-allergic cutaneous reactions--defined as irritative, follicular, or doubtful allergic reactions--were analysed in relationship with severity of chemical...... most severe groups of self-reported sensitivity to airborne chemicals. When adjusting for confounding, associations were weakened, and only non-allergic cutaneous reactions were significantly associated with individuals most severely affected by inhalation of airborne chemicals (odds ratio = 2.5, p = 0...
Contact glow discharge electrolysis: its origin, plasma diagnostics and non-faradaic chemical effects
Sen Gupta, Susanta K
Contact glow discharge electrolysis (CGDE) also termed plasma electrolysis is a novel electrolysis where a stable sheath of light emitting plasma develops around an electrode immersed well inside a relatively high-conductivity liquid electrolyte during normal electrolysis (NE) at several hundred volts. The phenomenon may develop in dc-, pulsed dc-, ac- as well as RF-driven electrolyses. The chemical effects of CGDE are remarkably non-faradaic in respect to the nature of the products as well as their yields. The article traces comprehensively the progress made in studies of CGDE in aqueous and non-aqueous solutions since 1844 and reviews the developments in the understanding of its origin, light emission, plasma state and non-faradaic effects leading to the elucidation of detailed mechanism of the origin of CGDE on the basis of the onset of hydrodynamic instabilities in local vaporization of the solvent near the working electrode during NE, and that of highly non-faradaic effects of CGDE based on a model of two reaction zones located within the electrode plasma and at the plasma–liquid interface producing solvent derived radicals at high local concentrations. Keeping in view the recent surge of interest in varied applications of CGDE, the article is appended with highlights of these applications across synthetic chemistry, waste water treatment, electrosurgical devices, nanoparticle fabrications, surface engineering and micro-machining. (topical review)
Contact sensitization in Dutch children and adolescents with and without atopic dermatitis - a retrospective analysis.
Lubbes, Stefanie; Rustemeyer, Thomas; Sillevis Smitt, Johannes H; Schuttelaar, Marie Louise; Middelkamp-Hup, Maritza A
Allergic contact dermatitis is known to occur in children with and without atopic dermatitis, but more data are needed on contact sensitization profiles in these two groups. To identify frequent allergens in children with and without atopic dermatitis suspected of having allergic contact dermatitis. A retrospective analysis of children aged 0-17 years patch tested between 1996 and 2013 was performed. Of all 1012 children tested because of suspected contact dermatitis, 46% developed one or more positive reactions, the proportions for children with (n = 526) and without (n = 395) atopic dermatitis being 48% and 47%, respectively. Children with atopic dermatitis reacted more often to lanolin alcohol (30% pet., p = 0.030), Amerchol L-101 (p = 0.030), and fragrances [fragrance mix I (p = 0.048) and Myroxylon pereirae (p = 0.005)]. Allergens outside the European baseline series that frequently gave positive reactions in these groups included cocamidopropyl betaine and Amerchol L-101. Reactivity to these allergens was significantly more common in atopic dermatitis children. Sensitization prevalences in children with and without atopic dermatitis were similar, but children with atopic dermatitis reacted significantly more often to lanolin alcohol and fragrances. Testing with additional series besides the European baseline series may be necessary, as reactions to, for example, cocamidopropyl betaine and Amerchol L-101 may otherwise be missed. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Occupational allergic contact dermatitis caused by sterile non-latex protective gloves: clinical investigation and chemical analyses.
Pontén, Ann; Hamnerius, Nils; Bruze, Magnus; Hansson, Christer; Persson, Christina; Svedman, Cecilia; Thörneby Andersson, Kirsten; Bergendorff, Ola
An increased frequency of occupational contact hand dermatitis among surgical operating theatre personnel has been noticed. To evaluate patients with occupational contact dermatitis caused by their rubber gloves, and to describe a method for analysing the content of the allergens in the gloves. Patch tests were performed with the baseline series, a rubber chemical series, and the patients' own gloves. A method for analysing 1,3-diphenylguanidine (DPG) and cetylpyridinium chloride in the gloves was developed. Contact allergy to thiuram mix was found in 8 of 16 patients, whereas 12 of 16 patients reacted to DPG. In 7 of 8 patients, contact allergy to cetylpyridinium chloride was found. In the patients' gloves, cetylpyridinium chloride and DPG were detected at higher concentrations on the inside of the gloves than on the outside. Most patients had worked for decades in their present occupations, but their hand dermatitis had only been present for months. Contact allergy to DPG in gloves has been disputed, but, in this study, we were able to confirm the presence of DPG and cetylpyridinium chloride in the causative gloves by using a modified method for the analysis. The presence of these chemicals in gloves caused an increase in occupational contact dermatitis in surgical operating theatre personnel. © 2012 John Wiley & Sons A/S.
Air-borne contact dermatitis due to Chrysanthemum with true cross sensitivity to Parthenium hysterophorus and Xanthium strumarium
Pasricha J
Full Text Available A 60-year old man living in Srinagar (Jammu and Kashmir had air-borne contact dermatitis for last 10 years. He had never traveled to any other part of the country where Parthenium hysterophorus or Xanthium strumarium are prevalent but he used to cultivate chrysanthemums. Patch tests with standardized extracts of various plants revealed the strongest reaction with Chrysanthemum, while the reactions with Xanthium strumarium and Parthenium hysterophorus were also positive but milder. This seems to be a case of primary sensitivity to Chrysanthemum with cross sensitivity to Xanthium strumarium and Parthenium hysterophorus.
Resonant characteristics and sensitivity dependency on the contact surface in QCM-micropillar-based system of coupled resonator sensors
Kashan, M A M; Kalavally, V; Ramakrishnan, N; Lee, H W
We report the characteristics and sensitivity dependence over the contact surface in coupled resonating sensors (CRSs) made of high aspect ratio resonant micropillars attached to a quartz crystal microbalance (QCM). Through experiments and simulation, we observed that when the pillars of resonant heights were placed in maximum displacement regions the resonance frequency of the QCM increased following the coupled resonance characteristics, as the pillar offered elastic loading to the QCM surface. However, the same pillars when placed in relatively lower displacement regions, in spite of their resonant dimension, offered inertial loading and resulted in a decrease in QCM resonance frequency, as the displacement amplitude was insufficient to couple the vibrations from the QCM to the pillars. Accordingly, we discovered that the coupled resonance characteristics not only depend on the resonant structure dimensions but also on the contact regions in the acoustic device. Further analysis revealed that acoustic pressure at the contact surface also influences the resonance frequency characteristics and sensitivity of the CRS. To demonstrate the significance of the present finding for sensing applications, humidity sensing is considered as the example measurand. When a sensing medium made of resonant SU-8 pillars was placed in a maximum displacement region on a QCM surface, the sensitivity increased by 14 times in comparison to a resonant sensing medium placed in a lower displacement region of a QCM surface. (paper)
Contact dermatitis in saffron workers: clinical profile and identification of contact sensitizers in a saffron-cultivating area of Kashmir Valley of North India.
Hassan, Iffat; Kamili, Afifa; Rasool, Farhan; Nehvi, Firdous; Rather, Parvaiz; Yasmin, Salwee; Pampori, Rafiq A; Jabeen, Yasmeen; Yaseen, Atiya; Bashir, Safia; Naaz, Saima
Saffron, a bulbous perennial plant belonging to Iridaceae family, is the most expensive cultivated herb that is widely used for industrial and nonindustrial purposes. However, besides its attractive and valuable properties, contact dermatitis due to saffron is an uncommon reported entity. The aims of this study were to determine the clinical pattern patch-testing profile of contact dermatitis in saffron workers and to identify the most common allergens/sensitizers. One hundred ten saffron workers were patch-tested with 39 allergens, which included Indian standard series antigens, plant series antigens, and extracts from different parts of saffron flower. The allergens in Indian standard series accounted for 52.44% of positive reactions. Plant series and different parts of saffron accounted for 47.56% of the positive reactions. Among those patients with positive responses to the supplemental saffron allergens, 83.3% were of present or past relevance. The data observed in the present study confirm that the saffron dermatitis is a distinct clinical entity with characteristic clinical presentation and has a strong significance as an occupational allergen in those handling this plant. Patch testing with different parts of saffron flower has a role to play in finding out the etiological cause.
Sensitivity enhancement by multiple-contact cross-polarization under magic-angle spinning.
Raya, J; Hirschinger, J
Multiple-contact cross-polarization (MC-CP) is applied to powder samples of ferrocene and l-alanine under magic-angle spinning (MAS) conditions. The method is described analytically through the density matrix formalism. The combination of a two-step memory function approach and the Anderson-Weiss approximation is found to be particularly useful to derive approximate analytical solutions for single-contact Hartmann-Hahn CP (HHCP) and MC-CP dynamics under MAS. We show that the MC-CP sequence requiring no pulse-shape optimization yields higher polarizations at short contact times than optimized adiabatic passage through the HH condition CP (APHH-CP) when the MAS frequency is comparable to the heteronuclear dipolar coupling, i.e., when APHH-CP through a single sideband matching condition is impossible or difficult to perform. It is also shown that the MC-CP sideband HH conditions are generally much broader than for single-contact HHCP and that efficient polarization transfer at the centerband HH condition can be reintroduced by rotor-asynchronous multiple equilibrations-re-equilibrations with the proton spin bath. Boundary conditions for the successful use of the MC-CP experiment when relying on spin-lattice relaxation for repolarization are also examined. Copyright © 2017 Elsevier Inc. All rights reserved.
An effect-directed strategy for characterizing emerging chemicals in food contact materials made from paper and board
Rosenmai, Anna Kjerstine; Bengtström, Linda; Taxvig, Camilla
Food contact materials (FCM) are any type of item intended to come into contact with foods and thus represent a potential source for human exposure to chemicals. Regarding FCMs made of paper and board, information pertaining to their chemical constituents and the potential impacts on human health...... FCMs exhibited activities in at least one assay. As proof-of-principle, FCM samples obtained from a sandwich wrapper and a pizza box were carried through a complete step-by-step multi-tiered approach. The pizza box exhibited ER activity, likely caused by the presence of bisphenol A, dibutyl phthalate......, and benzylbutyl phthalate. The sandwich wrapper exhibited AR antagonism, likely caused by abietic acid and dehydroabietic acid. Migration studies confirmed that the active chemicals can transfer from FCMs to food simulants. In conclusion, we report an effect-directed strategy that can identify hazards posed...
Chemical protection and sensitization to ionizing radiation:molecular investigations
Badiello, R.
Chemical radioprotection and radiosensitization are induced by the presence of certain chemical compounds, which reduce or enhance the effect of ionizing radiation on living organisms. Such substances are either naturally present or may be artificially introduced in the living cells. Chemical radioprotectors are interesting for possible application in the health protection of both professionally exposed workers and patients treated by radiation for diagnostic and thereapeutic purposes. Interest in chemical radiosensitization has increased recently because of its potential application in the radiotherapy of tumours. Both radioprotection and radiosensitization occur by means of complicated mechanisms, which at first correspond to very fast reactions. The mechanism of the interaction between such substances and radiation-induced biological radicals has been investigated by means of pulse radiolysis and rapid mixing techniques. Examples of the application of these techniques are given to illustrate how information has been obtained on the molecular basis of radiation chemical modi-fication at the cellular level. In particular some interactions between model systems of biological interest (DNA, DNA components, enzymes, amino acids, etc.) and sulphur-containing radioprotectors (glutathione, cysteine, etc.) and/or electroaffinic radiosensitizers, are described. (H.K.)
Sensitive and fast mutation detection by solid phase chemical cleavage
Hansen, Lise Lotte; Justesen, Just; Kruse, Torben A
We have developed a solid phase chemical cleavage method (SpCCM) for screening large DNA fragments for mutations. All reactions can be carried out in microtiterwells from the first amplification of the patient (or test) DNA through the search for mutations. The reaction time is significantly...... reduced compared to the conventional chemical cleavage method (CCM), and even by using a uniformly labelled probe, the exact position and nature of the mutation can be revealed. The SpCCM is suitable for automatization using a workstation to carry out the reactions and a fluorescent detection-based DNA...
Expression of surface markers on the human monocytic leukaemia cell line, THP-1, as indicators for the sensitizing potential of chemicals.
An, Susun; Kim, Seoyoung; Huh, Yong; Lee, Tae Ryong; Kim, Han-Kon; Park, Kui-Lea; Eun, Hee Chul
Evaluation of skin sensitization potential is an important part of the safety assessment of cosmetic ingredients and topical drugs. Recently, evaluation of changes in surface marker expression induced in dendritic cells (DC) or DC surrogate cell lines following exposure to chemicals represents one approach for in vitro test methods. The study aimed to test the change of expression patterns of surface markers on THP-1 cells by chemicals as a predictive in vitro method for contact sensitization. We investigated the expression of CD54, CD86, CD83, CD80, and CD40 after a 1-day exposure to sensitizers (1-chloro-2,4-dinitrobenzene; 2,4-dinitrofluorobenzene; benzocaine; 5-chloro-2-methyl-4-isothiazolin-3-one; hexyl cinnamic aldehyde; eugenol; nickel sulfate hexahydrate; potassium dichromate; cobalt sulfate; 2-mercaptobenzothiazole; and ammonium tetrachloroplatinate) and non-sensitizers (sodium lauryl sulfate, benzalkonium chloride, lactic acid, salicylic acid, isopropanol, and dimethyl sulphoxide). The test concentrations were 0.1x, 0.5x, and 1x of the 50% inhibitory concentration, and the relative fluorescence intensity was used as an expression indicator. By evaluating the expression patterns of CD54, CD86, and CD40, we could classify the chemicals as sensitizers or non-sensitizers, but CD80 and CD83 showed non-specific patterns of expression. These data suggest that the THP-1 cells are good model for screening contact sensitizers and CD40 could be a useful marker complementary to CD54 and CD86.
Contact sensitization to fragrances in the general population: a Koch's approach may reveal the burden of disease
Thyssen, J P; Menné, T; Linneberg, A
subjects were tested in total. The median prevalence of FM and MP sensitization among adults was 2.3% (women, 1.7%; men, 1.3%) and 1.1% (women, 1.4%; men, 0%), respectively. CONCLUSIONS: Based on the reliability of patch test data from the general population and exposure data obtained from patients...... the prevalence of fragrance sensitization in the general population, and to suggest how future population-based studies and questionnaires should be constructed, better to assess the prevalence and burden of fragrance sensitization. This is of relevance as it is often difficult to establish causality...... in biological systems. METHODS: A systematic review of the literature was carried out by searching Pubmed-Medline, Biosis and contact dermatitis textbooks. RESULTS: Nineteen studies were identified, of which 13 were performed among adults. Sample sizes varied between 82 and 2545 tested subjects, and 11 648...
Multicenter study of preservative sensitivity in patients with suspected cosmetic contact dermatitis in Korea.
Lee, Sang S; Hong, Dong K; Jeong, Nam J; Lee, Jeung H; Choi, Yun-Seok; Lee, Ai-Young; Lee, Cheol-Heon; Kim, Kea J; Park, Hae Y; Yang, Jun-Mo; Lee, Ga-Young; Lee, Joon; Eun, Hee C; Moon, Kee-Chan; Seo, Seong J; Hong, Chang K; Lee, Sang W; Choi, Hae Y; Lee, Jun Y
As many new cosmetic products are introduced into the market, attention must be given to contact dermatitis, which is commonly caused by cosmetics. We investigate the prevalence of preservative allergy in 584 patients with suspected cosmetic contact dermatitis at 11 different hospitals. From January 2010 to March 2011, 584 patients at 11 hospital dermatology departments presented with cosmetic contact dermatitis symptoms. These patients were patch-tested for preservative allergens. An irritancy patch test performed on 30 control subjects using allergens of various concentrations showed high irritancy rates. Preservative hypersensitivity was detected in 41.1% of patients. Allergens with the highest positive test rates were benzalkonium chloride (12.1%), thimerosal (9.9%) and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (5.5%). Benzalkonium chloride and chlorphenesin had the highest irritancy rate based on an irritancy patch test performed using various concentrations. Seven of 30 normal subjects had a positive irritant patch reading with 0.1% benzalkonium chloride and eight of 30 normal subjects had a positive irritant patch reading at 4 days with 0.5% chlorphenesin in petrolatum. Although benzalkonium chloride was highly positive for skin reactions in our study, most reactions were probably irritation. MCI/MI and thimerosal showed highly positive allergy reactions in our study. The optimum concentration of chlorphenesin to avoid skin reactions is less than 0.5%. © 2012 Japanese Dermatological Association.
Transparent front contact optimization in dye sensitized solar cells: use of cadmium stannate and titanium oxide by sputtering
Braga, A., E-mail: antonio.braga@iit.it [CNR-IDASC SENSOR Lab and Department of Chemistry and Physics, Brescia University, Via Valotti 9, 25131 Brescia (Italy); Baratto, C. [CNR-IDASC SENSOR Lab and Department of Chemistry and Physics, Brescia University, Via Valotti 9, 25131 Brescia (Italy); Bontempi, E. [INSTM and Chemistry for Technologies Laboratory, University of Brescia, Via Branze 28, 25133 Brescia (Italy); Colombi, P. [Centro Coating C.S.M.T. Gestione S.c.a.r.l., Via Branze, 45 25123 Brescia (Italy); Sberveglieri, G. [CNR-IDASC SENSOR Lab and Department of Chemistry and Physics, Brescia University, Via Valotti 9, 25131 Brescia (Italy)
A reliable transparent front contact of cadmium stannate (CTO) and titanium oxide (TiO{sub 2}) entirely deposited by magnetron sputtering has been studied and applied to build standard dye-sensitized solar cell. CTO gives very high average optical transmittance (T{sub avg} ≥ 90%) along with competitive sheet resistance (R{sub sheet} ≤ 15 Ω/sq), while a very thin layer of TiO{sub 2} (thickness < 5 nm) acts as buffer layer to prevent charge recombination. The matched materials allow achievement of good performances of the cells, in terms of short circuit current and power conversion efficiency. UV-visible spectrophotometry, glancing incident X-rays diffraction and X-rays reflectivity techniques were used to characterize thin films before cell realization; sealed solar cells were tested under simulated solar irradiance at 1 Sun to determine functional properties. - Highlights: • Double layer cadmium stannate–TiO{sub 2} transparent front contact by sputtering. • Very thin TiO{sub 2} buffer layer for charge recombination prevention. • Application of novel transparent contact in standard dye sensitized solar cells.
Fabrication and characterization of a multidirectional-sensitive contact-enhanced inertial microswitch with a electrophoretic flexible composite fixed electrode
Yang, Zhuoqing; Zhu, Bin; Chen, Wenguo; Ding, Guifu; Wang, Hong; Zhao, Xiaolin
A multidirectional-sensitive inertial microswitch with a polymer–metal composite fixed electrode has been designed and fabricated based on surface micromachining in this work. The microswitch mainly consists of a suspended proof mass as a movable electrode and a T-shaped structure on the substrate with maple leaf-like top and cantilevers around the central cylinder as vertical and lateral fixed electrodes. It can sense the applied shock accelerations from any radial direction in the xoy plane and z-axis. The new vertical composite fixed electrode of the switch is completed by electroplating and electrophoretic deposition, which can realize a flexible contact between the electrodes and reduce the bounces and prolong the contact time. As a result, the stability and reliability of the inertial switch could be greatly improved. The fabricated microswitches have been tested and characterized by a standard dropping hammer system. It is shown that the threshold acceleration of the prototype is generally uniform in different sensitive directions in the xoy plane and z-axis, which is about 70 g. The contact time of the microswitch with the composite fixed electrode is ∼110 µs in the vertical direction, which is longer than that (∼65 µs) without a polymer. The test data are in agreement with dynamic finite-element simulation results. (paper)
Braga, A.; Baratto, C.; Bontempi, E.; Colombi, P.; Sberveglieri, G.
A reliable transparent front contact of cadmium stannate (CTO) and titanium oxide (TiO 2 ) entirely deposited by magnetron sputtering has been studied and applied to build standard dye-sensitized solar cell. CTO gives very high average optical transmittance (T avg ≥ 90%) along with competitive sheet resistance (R sheet ≤ 15 Ω/sq), while a very thin layer of TiO 2 (thickness < 5 nm) acts as buffer layer to prevent charge recombination. The matched materials allow achievement of good performances of the cells, in terms of short circuit current and power conversion efficiency. UV-visible spectrophotometry, glancing incident X-rays diffraction and X-rays reflectivity techniques were used to characterize thin films before cell realization; sealed solar cells were tested under simulated solar irradiance at 1 Sun to determine functional properties. - Highlights: • Double layer cadmium stannate–TiO 2 transparent front contact by sputtering. • Very thin TiO 2 buffer layer for charge recombination prevention. • Application of novel transparent contact in standard dye sensitized solar cells
Effect of contact with male on the physical and chemical qualities of ...
A group of 30 Black HARCO laying hens were reared together with 3 mature cocks, while another group were reared in an adjacent pen without cocks. Thus, while the first group of hens had full physical contact (including mating) with the males, the second group was restricted only to auditory and visual contacts with the ...
Background: In recent years, it has been proposed that the primary mechanism for the development of food allergies is percutaneous sensitization. Since 2010, in Japan, the number of immediate-type wheat allergy due to hydrolyzed wheat protein has dramatically increased among those who have been using soap containing hydrolyzed wheat. This incidence supports the hypothesis that food allergens arise through percutaneous sensitization. Clinical Summary: A 25-year-old man (case 1) and an 18-year-...
Ethosome formulations of known contact allergens can increase their sensitizing capacity
Madsen, Jacob Torp; Vogel, Stefan; Karlberg, Ann-Therese
a modified local lymph node assay (LLNA). The results were compared with those for the same allergens in similar concentrations and vehicles without ethosomes. Both allergens encapsulated in 200-300 nm ethosomes showed increased sensitizing potency in the murine assay compared with the allergens in solution...... without ethosomes. Empty ethosomes were non-sensitizing according to LLNA. The clinical implications are so far uncertain, but increased allergenicity from ethosome-encapsulated topical product ingredients cannot be excluded....
Non-allergic cutaneous reactions in airborne chemical sensitivity--a population based study.
Berg, Nikolaj Drimer; Linneberg, Allan; Thyssen, Jacob Pontoppidan; Dirksen, Asger; Elberling, Jesper
Multiple chemical sensitivity (MCS) is characterised by adverse effects due to exposure to low levels of chemical substances. The aetiology is unknown, but chemical related respiratory symptoms have been found associated with positive patch test. The purpose of this study was to investigate the relationship between cutaneous reactions from patch testing and self-reported severity of chemical sensitivity to common airborne chemicals. A total of 3460 individuals participating in a general health examination, Health 2006, were patch tested with allergens from the European standard series and screened for chemical sensitivity with a standardised questionnaire dividing the participants into four severity groups of chemical sensitivity. Both allergic and non-allergic cutaneous reactions--defined as irritative, follicular, or doubtful allergic reactions--were analysed in relationship with severity of chemical sensitivity. Associations were controlled for the possible confounding effects of sex, age, asthma, eczema, atopic dermatitis, psychological and social factors, and smoking habits. In unadjusted analyses we found associations between allergic and non-allergic cutaneous reactions on patch testing and the two most severe groups of self-reported sensitivity to airborne chemicals. When adjusting for confounding, associations were weakened, and only non-allergic cutaneous reactions were significantly associated with individuals most severely affected by inhalation of airborne chemicals (odds ratio = 2.5, p = 0.006). Our results suggest that individuals with self-reported chemical sensitivity show increased non-allergic cutaneous reactions based on day 2 readings of patch tests. Copyright © 2011 Elsevier GmbH. All rights reserved.
Mass loss and chemical structures of wheat and maize straws in response to ultraviolet-B radiation and soil contact
Zhou, Guixiang; Zhang, Jiabao; Mao, Jingdong; Zhang, Congzhi; Chen, Lin; Xin, Xiuli; Zhao, Bingzi
The role of photodegradation, an abiotic process, has been largely overlooked during straw decomposition in mesic ecosystems. We investigated the mass loss and chemical structures of straw decomposition in response to elevated UV-B radiation with or without soil contact over a 12-month litterbag experiment. Wheat and maize straw samples with and without soil contact were exposed to three radiation levels: a no-sunlight control, ambient solar UV-B, and artificially elevated UV-B radiation. A block control with soil contact was not included. Compared with the no-sunlight control, UV-B radiation increased the mass loss by 14–19% and the ambient radiation by 9–16% for wheat and maize straws without soil contact after 12 months. Elevated UV-B exposure decreased the decomposition rates of both wheat and maize straws when in contact with soil. Light exposure resulted in decreased O-alkyl carbons and increased alkyl carbons for both the wheat and maize straws compared with no-sunlight control. The difference in soil contact may influence the contribution of photodegradation to the overall straw decomposition process. These results indicate that we must take into account the effects of photodegradation when explaining the mechanisms of straw decomposition in mesic ecosystems. PMID:26423726
Mass loss and chemical structures of wheat and maize straws in response to ultraviolet-B radiation and soil contact.
The role of photodegradation, an abiotic process, has been largely overlooked during straw decomposition in mesic ecosystems. We investigated the mass loss and chemical structures of straw decomposition in response to elevated UV-B radiation with or without soil contact over a 12-month litterbag experiment. Wheat and maize straw samples with and without soil contact were exposed to three radiation levels: a no-sunlight control, ambient solar UV-B, and artificially elevated UV-B radiation. A block control with soil contact was not included. Compared with the no-sunlight control, UV-B radiation increased the mass loss by 14-19% and the ambient radiation by 9-16% for wheat and maize straws without soil contact after 12 months. Elevated UV-B exposure decreased the decomposition rates of both wheat and maize straws when in contact with soil. Light exposure resulted in decreased O-alkyl carbons and increased alkyl carbons for both the wheat and maize straws compared with no-sunlight control. The difference in soil contact may influence the contribution of photodegradation to the overall straw decomposition process. These results indicate that we must take into account the effects of photodegradation when explaining the mechanisms of straw decomposition in mesic ecosystems.
Pressure vessel steels: influence of chemical composition on irradiation sensitivity
Ghoniem, M.M.; Hammad, F.H.
Neutron irradiation of the steels used in the construction of the nuclear reactor pressure vessels can lead to the embrittlement of these materials, increasing the ductile-to-brittle transition temperature and decreasing the fracture energy, which can limit the plant life. The knowledge of irradiation embrittlement and the means for minimizing such degradation is therefore important in the field of assuring the safety of the nuclear power plants. Irradiation embrittlement is quite a complex process. It involves many variables. The most important of these are irradiation temperature, neutron fluence (neutron dose), neutron flux (neutron dose rate), and chemical composition of the irradiated material. This paper is concerned with the effect of chemical composition, the role of residual and alloying elements in the irradiation embrittlement of nuclear reactor pressure vessel steels in light water reactors. It presents a critical review for the published work in this field through the last 25 years
the relationship between cutaneous reactions from patch testing and self-reported severity of chemical sensitivity to common airborne chemicals. A total of 3460 individuals participating in a general health examination, Health 2006, were patch tested with allergens from the European standard series and screened...... most severe groups of self-reported sensitivity to airborne chemicals. When adjusting for confounding, associations were weakened, and only non-allergic cutaneous reactions were significantly associated with individuals most severely affected by inhalation of airborne chemicals (odds ratio = 2.5, p = 0...
A study of the enhanced sensitizing capacity of a contact allergen in lipid vesicle formulations
Simonsson, Carl; Madsen, Jakob Torp; Graneli, Annette
, an indicator of a compounds sensitizing capacity, increased when RBITC was applied in lipid vesicles as compared to an ethanol:water (Et:W) solution. Micro-scale vesicles showed a slightly higher cell proliferative response compared to nano-scale vesicles. TPM imaging revealed that the vesicle formulations...... improved the skin penetration of RBITC compared to the Et:W solution. A strong fluorescent region in the stratum corneum and upper epidermis implies elevated association of RBITC to these skin layers when formulated in lipid vesicles. In conclusion, the results indicate that there could be an elevated risk...... of sensitization when haptens are delivered in vehicles containing lipid vesicles. Although the size of the vesicles seems to be of minor importance, further studies are needed before a more generalized conclusion can be drawn. It is likely that the enhanced sensitizing capacity is a consequence of the improved...
A simple in chemico method for testing skin sensitizing potential of chemicals using small endogenous molecules.
Nepal, Mahesh Raj; Shakya, Rajina; Kang, Mi Jeong; Jeong, Tae Cheon
Among many of the validated methods for testing skin sensitization, direct peptide reactivity assay (DPRA) employs no cells or animals. Although no immune cells are involved in this assay, it reliably predicts the skin sensitization potential of a chemical in chemico. Herein, a new method was developed using endogenous small-molecular-weight compounds, cysteamine and glutathione, rather than synthetic peptides, to differentiate skin sensitizers from non-sensitizers with an accuracy as high as DPRA. The percent depletion of cysteamine and glutathione by test chemicals was measured by an HPLC equipped with a PDA detector. To detect small-size molecules, such as cysteamine and glutathione, a derivatization by 4-(4-dimethylaminophenylazo) benzenesulfonyl chloride (DABS-Cl) was employed prior to the HPLC analysis. Following test method optimization, a cut-off criterion of 7.14% depletion was applied to differentiate skin sensitizers from non-sensitizers in combination of the ratio of 1:25 for cysteamine:test chemical with 1:50 for glutathione:test chemical for the best predictivity among various single or combination conditions. Although overlapping HPLC peaks could not be fully resolved for some test chemicals, high levels of sensitivity (100.0%), specificity (81.8%), and accuracy (93.3%) were obtained for 30 chemicals tested, which were comparable or better than those achieved with DPRA. Copyright © 2018 Elsevier B.V. All rights reserved.
Chemical and volatile composition of jujube wines fermented by Saccharomyces cerevisiae with and without pulp contact and protease treatment
Wenye ZHANG
Full Text Available Abstract This study evaluated the chemical and volatile composition of jujube wines fermented with Saccharomyces cerevisiae A1.25 with and without pulp contact and protease treatment during fermentation. Yeast cell population, total reducing sugar and methanol contents had significant differences between nonextracted and extracted wine. The nonextracted wines had significantly higher concentrations of ethyl 9-hexadecenoate, ethyl palmitate and ethyl oleate than the extracted wines. Pulp contact also could enhance phenylethyl alcohol, furfuryl alcohol, ethyl palmitat and ethyl oleate. Furthermore, protease treatment can accelerate the release of fusel oils. The first principal component separated the wine from the extracted juice without protease from other samples based on the higher concentrations of medium-chain fatty acids and medium-chain ethyl esters. Sensory evaluation showed pulp contact and protease could improve the intensity and complexity of wine aroma due to the increase of the assimilable nitrogen.
Methylisothiazolinone testing at 2000 ppm: a prevalent sensitizer for allergic contact dermatitis.
Ham, Kaiya; Posso-De Los Rios, Claudia J; Gooderham, Melinda
Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) have been identified as potent allergens. The optimal MI concentration for patch testing for reaction to these agents has not yet been identified, but it has been suggested that testing MI at 2000 ppm may reduce false-negative reactions. The aim of this study was to report allergic reactions to MI and MCI/MI detected in a community dermatology practice setting in Ontario, Canada. The patch test records of patients with suspected allergic contact dermatitis seen between October 2007 and June 2014 were reviewed. We compared positive patch testing before and after December 2011 when a higher MI concentration was used (2000 ppm aqueous) in addition to the baseline series MCI/MI at 100 ppm. A total of 794 patient records were reviewed. There were 38 true-positive reactions to MI or MCI/MI. Of these 38 patients, 26 (68%) were female. We detected an overall increase in the rate of positive patch testing to MCI/MI, MI alone, or both from 3.13% to 7.45% when MI concentration was introduced at 2000 ppm aqueous. Occupational differences existed between sexes. The addition of MI at 2000 ppm to our screening series effectively increased the detection of MI-induced allergic contact dermatitis.
Shotgun lipidomic analysis of chemically sulfated sterols compromises analytical sensitivity
Casanovas, Albert; Hannibal-Bach, Hans Kristian; Jensen, Ole Nørregaard
Shotgun lipidomics affords comprehensive and quantitative analysis of lipid species in cells and tissues at high-throughput [1 5]. The methodology is based on direct infusion of lipid extracts by electrospray ionization (ESI) combined with tandem mass spectrometry (MS/MS) and/or high resolution F...... low ionization efficiency in ESI [7]. For this reason, chemical derivatization procedures including acetylation [8] or sulfation [9] are commonly implemented to facilitate ionization, detection and quantification of sterols for global lipidome analysis [1-3, 10]....
Chemical and electrical characteristics of annealed Ni/Au and Ni/Ir/Au contacts on AlGaN
Ngoepe, P.N.M., E-mail: phuti.ngoepe@up.ac.za [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Meyer, W.E.; Auret, F.D.; Omotoso, E.; Diale, M. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Swart, H.C.; Duvenhage, M.M.; Coetsee, E. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)
The evolution of Ni/Au and Ni/Ir/Au metal contacts deposited on AlGaN was investigated at different annealing temperatures. The samples were studied with electrical and chemical composition techniques. I–V characteristics of the Schottky diodes were optimum after 500 and 600 °C annealing for Ni/Au and Ni/Ir/Au based diodes, respectively. The depth profiles of the contacts were measured by x-ray photoelectron spectroscopy and time of flight secondary ion mass spectroscopy. These chemical composition techniques were used to examine the evolution of the metal contacts in order to verify the influence the metals have on the electrical properties of the diodes. The insertion of Ir as a diffusion barrier between Ni and Au effected the electrical properties, improving the stability of the contacts at high temperatures. Gold diffused into the AlGaN film, degrading the electrical properties of the Ni/Au diode. At 500 °C, the insertion of Ir, however, prevented the in-diffusion of Au into the AlGaN substrate.
Simonsson, Carl; Madsen, Jakob Torp; Graneli, Annette; Andersen, Klaus E.; Karlberg, Ann-Therese; Jonsson, Charlotte A.; Ericson, Marica B.
The growing focus on nanotechnology and the increased use of nano-sized structures, e.g. vesicles, in topical formulations has led to safety concerns. We have investigated the sensitizing capacity and penetration properties of a fluorescent model compound, rhodamine B isothiocyanate (RBITC), when administered in micro- and nano-scale vesicle formulations. The sensitizing capacity of RBITC was studied using the murine local lymph node assay (LLNA) and the skin penetration properties were compared using diffusion cells in combination with two-photon microscopy (TPM). The lymph node cell proliferation, an indicator of a compounds sensitizing capacity, increased when RBITC was applied in lipid vesicles as compared to an ethanol:water (Et:W) solution. Micro-scale vesicles showed a slightly higher cell proliferative response compared to nano-scale vesicles. TPM imaging revealed that the vesicle formulations improved the skin penetration of RBITC compared to the Et:W solution. A strong fluorescent region in the stratum corneum and upper epidermis implies elevated association of RBITC to these skin layers when formulated in lipid vesicles. In conclusion, the results indicate that there could be an elevated risk of sensitization when haptens are delivered in vehicles containing lipid vesicles. Although the size of the vesicles seems to be of minor importance, further studies are needed before a more generalized conclusion can be drawn. It is likely that the enhanced sensitizing capacity is a consequence of the improved penetration and increased formation of hapten-protein complexes in epidermis when RBITC is delivered in ethosomal formulations. - Graphical Abstract: Display Omitted
Identification of Lilial as a fragrance sensitizer in a perfume by bioassay-guided chemical fractionation and structure-activity relationships.
Arnau, E G; Andersen, K E; Bruze, M; Frosch, P J; Johansen, J D; Menné, T; Rastogi, S C; White, I R; Lepoittevin, J P
Fragrance materials are among the most common causes of allergic contact dermatitis. The aim of this study was to identify in a perfume fragrance allergens not included in the fragrance mix, by use of bioassay-guided chemical fractionation and chemical analysis/structure-activity relationships (SARs). The basis for the investigation was a 45-year-old woman allergic to her own perfume. She had a negative patch test to the fragrance mix and agreed to participate in the study. Chemical fractionation of the perfume concentrate was used for repeated patch testing and/or repeated open application test on the pre-sensitized patient. The chemical composition of the fractions giving a positive patch-test response and repeated open application test reactions was obtained by gas chromatography-mass spectrometry. From the compounds identified, those that contained a "structural alert" in their chemical structure, indicating an ability to modify skin proteins and thus behave as a skin sensitizer, were tested on the patient. The patient reacted positively to the synthetic fragrance p-t-butyl-alpha-methylhydrocinnamic aldehyde (Lilial), a widely used fragrance compound not present in the fragrance mix. The combination of bioassay-guided chemical fractionation and chemical analysis/structure-activity relationships seems to be a valuable tool for the investigation of contact allergy to fragrance materials.
Sun, Jian; Kosel, Jü rgen
be attributed to an additional influence coming from the Hall effect. Output sensitivities of 0.19 mV/T at zero-field and 0.2 mV/T at 0.01 T have been measured in the device, which is equivalent to the ones of the conventional EMR sensors with a bias of ∼0.04 T
Madsen, Jakob Torp; Vogel, Stefan; Karlberg, Ann-Therese
Vesicular systems, such as liposomes and ethosomes, are used in cosmetic and pharmaceutical products to encapsulate ingredients, to protect ingredients from degradation, to increase bioavailability, and to improve cosmetic performance. Some reports have suggested that formulation of cosmetic ingr...... without ethosomes. Empty ethosomes were non-sensitizing according to LLNA. The clinical implications are so far uncertain, but increased allergenicity from ethosome-encapsulated topical product ingredients cannot be excluded....
An elevated pro-inflammatory cytokine profile in multiple chemical sensitivity
Dantoft, Thomas Meinertz; Elberling, J.; Brix, Susanne
BackgroundMultiple chemical sensitivity (MCS) is a medically unexplained condition characterized by reports of recurrent unspecific symptoms attributed to exposure to low levels of common volatile chemicals. The etiology of MCS is poorly understood, but dysregulation of the immune system has been...
radioactive survey on the contact zone (paleogene - neogene) in Ad-Daww basin of Syria, using alpha sensitive plastic film technique
Mouty, M.; Al-Hilal, M.; Kattaa, B.
A detailed radon survey has been carried out over the contact zone of marine Paleogene and continental Neogene Formations in Ad-Daww basin (Central Syria), for the purpose of uranium exploration. Radon measurements were performed in a grid pattern using alpha sensitive plastic film technique, type 1B CN-85. Radon concentrations in soil were monitored across the aforementioned zone for 1.5 year, from April 93 to July 94, and their average has been calculated. Alpha Track density was found to be varying from 81 to 227 T/mm2 in Qarytein station, 65 to 124 T/mm2 in Bardeh station and 101 to 196 T/mm2 in Tyas station. The results of this work showed that the anomalous radon values were found to be corresponded to the Oligocene-Miocene geological surface in the study area. These relatively high values are most likely related to scattered uranium mineralization precipitated on surface along a chemically reducing zone where surface water of terrestrial and marine origin intermingled. A comparison between gamma count rate and trak etch density revealed a fairly good correlation, which indicates that the uranium occurrences on the geological contact (Oli - Mio) in Ad-Daww basin are of surficial nature. However, this may give a preliminary indication of probable subsurface extension of these occurrences preserved at depth away from surfacial weathering. (author). 6 refs., 2 tabs
An in vitro method for detecting chemical sensitization using human reconstructed skin models and its applicability to cosmetic, pharmaceutical, and medical device safety testing.
McKim, James M; Keller, Donald J; Gorski, Joel R
Chemical sensitization is a serious condition caused by small reactive molecules and is characterized by a delayed type hypersensitivity known as allergic contact dermatitis (ACD). Contact with these molecules via dermal exposure represent a significant concern for chemical manufacturers. Recent legislation in the EU has created the need to develop non-animal alternative methods for many routine safety studies including sensitization. Although most of the alternative research has focused on pure chemicals that possess reasonable solubility properties, it is important for any successful in vitro method to have the ability to test compounds with low aqueous solubility. This is especially true for the medical device industry where device extracts must be prepared in both polar and non-polar vehicles in order to evaluate chemical sensitization. The aim of this research was to demonstrate the functionality and applicability of the human reconstituted skin models (MatTek Epiderm(®) and SkinEthic RHE) as a test system for the evaluation of chemical sensitization and its potential use for medical device testing. In addition, the development of the human 3D skin model should allow the in vitro sensitization assay to be used for finished product testing in the personal care, cosmetics, and pharmaceutical industries. This approach combines solubility, chemical reactivity, cytotoxicity, and activation of the Nrf2/ARE expression pathway to identify and categorize chemical sensitizers. Known chemical sensitizers representing extreme/strong-, moderate-, weak-, and non-sensitizing potency categories were first evaluated in the skin models at six exposure concentrations ranging from 0.1 to 2500 µM for 24 h. The expression of eight Nrf2/ARE, one AhR/XRE and two Nrf1/MRE controlled gene were measured by qRT-PCR. The fold-induction at each exposure concentration was combined with reactivity and cytotoxicity data to determine the sensitization potential. The results demonstrated that
Further observations on sensitization of chemically stabilized stainless steels
Samans, C.H.; Kinoshita, K.; Matsushima, I.
Niobium additions to an 18Cr:8Ni type matrix reduce carbon solubility to such an extent that any ''solution treatment'' below 1150 0 C causes stabilization. Consequently, no Cr 23 C 6 precipitates at lower temperatures to sensitize the structure. Further observations on Type 321 suggest that two types of TiC precipitate from solid solution in an 18 : 8 type matrix. The size of the TiC nucleus decreases with the precipitating temperature. Above 1050 to 1100 0 C the initial TiC is probably incoherent, large enough to be stable, and resistant to ferric sulfate-sulfuric acid solution. Below 1050 to 1100 0 C the initial TiC, known as ''dot TiC'' or ''TiC on dislocations,'' is probably coherent, not large enough to be stable without further growth, and not resistant to ferric sulfate-sulfuric acid solution. During holding at temperatures below 1050 to 1100 0 C, stabilization occurs as the TiC on dislocations agglomerates to larger, incoherent particles. The time required increases as the temperature decreases down to the minimum TiC nucleation temperature near 610 0 C. Cold work makes it easier for the coherent particles to become incoherent, in effect facilitating approach to equilibrium carbon solubility at any temperature. Once chromium carbide forms, dissolved titanium eventually reacts with it, forming TiC and releasing chromium to desensitize the structure. This reaction can occur, given sufficient time for titanium diffusion, at any temperature at which chromium carbide nucleates. It is much more rapid than back diffusion of chromium from the matrix
Smart structure with elastomeric contact surface for prosthetic fingertip sensitivity development
Gu, Chunxin; Liu, Weiting; Yu, Ping; Cheng, Xiaoying; Fu, Xin
Current flexible/compliant tactile sensors suffer from low sensitivity and high hysteresis introduced by the essential viscosity characteristic of soft material, either used as compliant sensing element or as flexible coverage. To overcome these disadvantages, this paper focuses on developing a tactile sensor with a smart hybrid structure to obtain comprehensive properties in terms of size, compliance, robustness and pressure sensing ability so as to meet the requirements of limited space applications such as prosthetic fingertips. Employing micro-fabricated tiny silicon-based pressure die as the sensing element, it is easy to have both small size and good mechanical performance. To protect it from potential damage and maintain the compliant surface, a rigid base and a soft layer form a sealed chamber and encapsulate the fixed die together with fluid. The fluid serves as highly efficient pressure propagation media of mechanical stimulus from the compliant skin to the pressure die without any hazard impacting the vulnerable connecting wires. To understand the pressure transmission mechanism, a simplified and concise analytic model of a spring system is proposed. Using easy fabrication technologies, a prototype of a 3 × 3 sensor array with total dimensions of 14 mm × 14 mm × 6.5 mm was developed. Based on the quasi-linear relationship between fluid volume and pressure, finite element modeling was developed to analyze the chamber deformation and pressure output of the sensor cell. Experimental tests of the sensor prototype were implemented. The results showed that the sensor cell had good sensing performance with sensitivity of 19.9 mV N-1, linearity of 0.998, repeatability error of 3.41%, and hysteresis error of 3.34%. The force sensing range was from 5 mN to 1.6 N.
Predicting the sensitivity of populations from individual exposure to chemicals: the role of ecological interactions.
Gabsi, Faten; Schäffer, Andreas; Preuss, Thomas G
Population responses to chemical stress exposure are influenced by nonchemical, environmental processes such as species interactions. A realistic quantification of chemical toxicity to populations calls for the use of methodologies that integrate these multiple stress effects. The authors used an individual-based model for Daphnia magna as a virtual laboratory to determine the influence of ecological interactions on population sensitivity to chemicals with different modes of action on individuals. In the model, hypothetical chemical toxicity targeted different vital individual-level processes: reproduction, survival, feeding rate, or somatic growth rate. As for species interactions, predatory and competition effects on daphnid populations were implemented following a worst-case approach. The population abundance was simulated at different food levels and exposure scenarios, assuming exposure to chemical stress solely or in combination with either competition or predation. The chemical always targeted one vital endpoint. Equal toxicity-inhibition levels differently affected the population abundance with and without species interactions. In addition, population responses to chemicals were highly sensitive to the environmental stressor (predator or competitor) and to the food level. Results show that population resilience cannot be attributed to chemical stress only. Accounting for the relevant ecological interactions would reduce uncertainties when extrapolating effects of chemicals from individuals to the population level. Validated population models should be used for a more realistic risk assessment of chemicals. © 2014 SETAC.
Some Sensitivity Studies of Chemical Transport Simulated in Models of the Soil-Plant-Litter System
Begovich, C.L.
Fifteen parameters in a set of five coupled models describing carbon, water, and chemical dynamics in the soil-plant-litter system were varied in a sensitivity analysis of model response. Results are presented for chemical distribution in the components of soil, plants, and litter along with selected responses of biomass, internal chemical transport (xylem and phloem pathways), and chemical uptake. Response and sensitivity coefficients are presented for up to 102 model outputs in an appendix. Two soil properties (chemical distribution coefficient and chemical solubility) and three plant properties (leaf chemical permeability, cuticle thickness, and root chemical conductivity) had the greatest influence on chemical transport in the soil-plant-litter system under the conditions examined. Pollutant gas uptake (SO{sub 2}) increased with change in plant properties that increased plant growth. Heavy metal dynamics in litter responded to plant properties (phloem resistance, respiration characteristics) which induced changes in the chemical cycling to the litter system. Some of the SO{sub 2} and heavy metal responses were not expected but became apparent through the modeling analysis.
Monitoring contact sensitization to p-phenylenediamine (PPD) by patch testing with PPD 0.3% in petrolatum.
Geier, Johannes; Ballmer-Weber, Barbara K; Dickel, Heinrich; Frosch, Peter J; Bircher, Andreas; Weisshaar, Elke; Hillen, Uwe
Being a contact allergen of general relevance, p-phenylenediamine (PPD) is patch tested in the baseline series. However, PPD 1% in petrolatum may actively sensitize. Patch testing with PPD at 0.35% pet. proved to be safe, as far as active sensitization is concerned. To determine whether PPD 0.3% pet. reliably detects PPD sensitization. Patch testing with PPD 0.3% pet. and 1% pet. synchronously was performed in consecutive patients in a multicentre study within the Information Network of Departments of Dermatology. Altogether, 2042 patients were patch tested. PPD 1% pet. yielded 6.0% positive reactions (n = 123), and PPD 0.3% pet. yielded 4.7% (n = 95). The synchronous reproducibility of PPD reactions was similar as known from parallel patch tests with identical PPD concentrations. The diagnostic properties of PPD 0.3% pet. expressed as reaction index and positivity ratio were good. Of the 123 patients reacting to PPD 1% pet., 32 (26%) had no positive reaction to PPD 0.3% pet. In 22 of these 32 patients (69%), no clinical relevance could be found. As patch testing with PPD 0.3% pet. is reliable according to our results, we recommend replacing PPD 1% pet. in the baseline series with PPD 0.3% pet. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Development and utilization of an ex vivo bromodeoxyuridine local lymph node assay protocol for assessing potential chemical sensitizers.
Williams, W C; Copeland, C; Boykin, E; Quell, S J; Lehmann, D M
The murine local lymph node assay (LLNA) is widely used to identify chemicals that may cause allergic contact dermatitis. Exposure to a dermal sensitizer results in proliferation of local lymph node T cells, which has traditionally been measured by in vivo incorporation of [(3) H]methyl thymidine. A more recent non-isotopic variation of the assay utilizes bromodeoxyuridine (BrdU) incorporation in vivo. To further improve the utility of this assay, we developed an ex vivo BrdU labeling procedure eliminating the need for in vivo injections. The results of this assay correctly identified a strong sensitizer (i.e., trimellitic anhydride) as well as weak/moderate sensitizers (i.e., eugenol, cinnamaldehyde and hexylcinnaminic aldehyde). As anticipated, neither non-sensitizers isopropanol and lactic acid nor the false negative chemical nickel II sulfate hexahydrate induced a positive threshold response in the assay. The results of this assay are in close agreement with those of the in vivo LLNA:BrdU-enzyme-linked immunosorbent assay labeling procedure. We also used the ex vivo BrdU LLNA procedure to evaluate ammonium hexachloroplatinate, ammonium tetrachloroplatinate and cis-diamminedichloroplatinum(II) and the assay correctly identified them as sensitizers based on the calculation of EC2 values. We conclude that this ex vivo BrdU labeling method offers predictive capacity comparable to previously established LLNA protocols while eliminating animal injections and the use of radioisotope. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
PH Sensitive Polymers for Improving Reservoir Sweep and Conformance Control in Chemical Flooring
Mukul Sharma; Steven Bryant; Chun Huh
There is an increasing opportunity to recover bypassed oil from depleted, mature oilfields in the US. The recovery factor in many reservoirs is low due to inefficient displacement of the oil by injected fluids (typically water). The use of chemical flooding methods to increase recovery efficiencies is severely constrained by the inability of the injected chemicals to contact the bypassed oil. Low sweep efficiencies are the primary cause of low oil recoveries observed in the field in chemical flooding operations even when lab studies indicate high oil recovery efficiency. Any technology that increases the ability of chemical flooding agents to better contact the remaining oil and reduce the amount of water produced in conjunction with the produced oil will have a significant impact on the cost of producing oil domestically in the US. This translates directly into additional economically recoverable reserves, which extends the economic lives of marginal and mature wells. The objective of this research project was to develop a low-cost, pH-triggered polymer for use in IOR processes to improve reservoir sweep efficiency and reservoir conformance in chemical flooding. Rheological measurements made on the polymer solution, clearly show that it has a low viscosity at low pH and exhibits a sudden increase in viscosity (by 2 orders of magnitude or more) at a pH of 3.5 to 4. This implies that the polymer would preferentially flow into zones containing water since the effective permeability to water is highest in these zones. As the pH of the zone increases due to the buffering capacity of the reservoir rock, the polymer solution undergoes a liquid to gel transition causing a sharp increase in the viscosity of the polymer solution in these zones. This allows operationally robust, in-depth conformance treatment of such water bearing zones and better mobility control. The rheological properties of HPAM solutions were measured. These include: steady-shear viscosity and
Allergic contact dermatitis from ophthalmic products: can pre-treatment with sodium lauryl sulfate increase patch test sensitivity?
Corazza, Monica; Virgili, Annarosa
In patients suspected of allergic contact dermatitis because of topical ophthalmic medicaments, patch tests performed with patients' own products are often negative. The irritant anionic surfactant sodium lauryl sulfate (SLS) may alter the stratum corneum and increase antigen penetration. Pre-treatment of the skin with SLS 0.5% for 24 h was performed in the sites of patch tests with patients' own products in 15 selected patients. In patients previously negative to their own products tested with conventional patch tests, SLS pre-treatment showed 6 new relevant positive reactions and induced a stronger positive reaction in 1 patient. SLS pre-treatment could be proposed as an alternative promising method, which may increase sensitivity of patch tests with patients' own products.
Amphibian Metamorphosis: A Sensitive Life Stage to Chemical and Non-chemical Stressors
Amphibian metamorphosis is a dynamic period of post-embryonic development which transforms the larval anuran into the juvenile. The body structure is remodeled through a variety of processes which may be perturbed by exposure to chemicals as well as other environmental stressors....
Local lymph node assay (LLNA) for detection of sensitization capacity of chemicals.
Gerberick, G Frank; Ryan, Cindy A; Dearman, Rebecca J; Kimber, Ian
The local lymph node assay (LLNA) is a murine model developed to evaluate the skin sensitization potential of chemicals. The LLNA is an alternative approach to traditional guinea pig methods and in comparison provides important animal welfare benefits. The assay relies on measurement of events induced during the induction phase of skin sensitization, specifically lymphocyte proliferation in the draining lymph nodes which is a hallmark of a skin sensitization response. Since its introduction the LLNA has been the subject of extensive evaluation on a national and international scale, and has been successfully validated and incorporated worldwide into regulatory guidelines. Experience gained in recent years has demonstrated that adherence to published procedures and guidelines for the LLNA (e.g., with respect to dose and vehicle selection) is critical for the successful conduct and eventual interpretation of the data. In addition to providing a robust method for skin sensitization hazard identification, the LLNA has proven very useful in assessing the skin sensitizing potency of test chemicals, and this has provided invaluable information to risk assessors. The primary method to make comparisons of the relative potency of chemical sensitizers is to use linear interpolation to estimate the concentration of chemical required to induce a stimulation index of three relative to concurrent vehicle-treated controls (EC3). In certain situations where there are available less than optimal dose response data a log-linear extrapolation method can be used to estimate an EC3 value which can reduce significantly the need for repeat testing of chemicals. The LLNA, when conducted according to published guidelines, provides a robust method for skin sensitization testing that not only provides reliable hazard identification information but also data necessary for effective risk assessment and risk management.
Keratinocyte gene expression profiles discriminate sensitizing and irritating compounds
Briel, R.J. van de; Pennings, J.L.A.; Baken, K.A.; Pronk, T.E.; Boorsma, A.; Gottschalk, R.; Loveren, H. van
Many chemicals can induce allergic contact dermatitis. Because evaluation of skin sensitizing potential by animal testing is prohibited for cosmetics, and screening of many chemicals is required within Registration, Evaluation, Authorisation and Restriction of Chemicals, urgent need exists for
Pred-Skin: A Fast and Reliable Web Application to Assess Skin Sensitization Effect of Chemicals.
Braga, Rodolpho C; Alves, Vinicius M; Muratov, Eugene N; Strickland, Judy; Kleinstreuer, Nicole; Trospsha, Alexander; Andrade, Carolina Horta
Chemically induced skin sensitization is a complex immunological disease with a profound impact on quality of life and working ability. Despite some progress in developing alternative methods for assessing the skin sensitization potential of chemical substances, there is no in vitro test that correlates well with human data. Computational QSAR models provide a rapid screening approach and contribute valuable information for the assessment of chemical toxicity. We describe the development of a freely accessible web-based and mobile application for the identification of potential skin sensitizers. The application is based on previously developed binary QSAR models of skin sensitization potential from human (109 compounds) and murine local lymph node assay (LLNA, 515 compounds) data with good external correct classification rate (0.70-0.81 and 0.72-0.84, respectively). We also included a multiclass skin sensitization potency model based on LLNA data (accuracy ranging between 0.73 and 0.76). When a user evaluates a compound in the web app, the outputs are (i) binary predictions of human and murine skin sensitization potential; (ii) multiclass prediction of murine skin sensitization; and (iii) probability maps illustrating the predicted contribution of chemical fragments. The app is the first tool available that incorporates quantitative structure-activity relationship (QSAR) models based on human data as well as multiclass models for LLNA. The Pred-Skin web app version 1.0 is freely available for the web, iOS, and Android (in development) at the LabMol web portal ( http://labmol.com.br/predskin/ ), in the Apple Store, and on Google Play, respectively. We will continuously update the app as new skin sensitization data and respective models become available.
Sensitivity of the Early Development of Ramshorn Snail, Marisa cornuarietis (Ampullariidae) to Environmental Chemicals
Sawasdee, Banthita
In this study, the suitability of the M. cornuarietis embryo toxicity test (MariETT) for environmental chemicals was investigated. The purpose of this study was to determine the sensitivity of the recently introduced M. cornuarietis embryo toxicity test (MariETT) using selected metals (inorganic pollutants) and pesticides (organic pollutants), and to compare its sensitivity and practicability to other established bioassay. The following endpoints were observed: mortality, formation of tentacl...
Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films
Belibel, R.; Avramoglou, T. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Garcia, A. [CNRS UPR 3407, Laboratoire des Sciences des Procédés et des Matériau, Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Barbaud, C. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Mora, L., E-mail: Laurence.mora@univ-paris13.fr [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France)
Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid–base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie–Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. - Highlights: • We develop different polymers with various chemical compositions. • Wettability properties were calculated using Cassie corrected contact angles. • Percentage of acid groups in polymers is directly correlated to acid part of SFE. • Cassie corrections are necessary for heterogeneous polymers.
Identification of Lilial as a fragrance sensitizer in a perfume by bioassay-guided chemical fractionation and structure-activity relationships
Arnau, E G; Andersen, Klaus Ejner; Bruze, M
Fragrance materials are among the most common causes of allergic contact dermatitis. The aim of this study was to identify in a perfume fragrance allergens not included in the fragrance mix, by use of bioassay-guided chemical fractionation and chemical analysis/structure-activity relationships...... (SARs). The basis for the investigation was a 45-year-old woman allergic to her own perfume. She had a negative patch test to the fragrance mix and agreed to participate in the study. Chemical fractionation of the perfume concentrate was used for repeated patch testing and/or repeated open application......" in their chemical structure, indicating an ability to modify skin proteins and thus behave as a skin sensitizer, were tested on the patient. The patient reacted positively to the synthetic fragrance p-t-butyl-alpha-methylhydrocinnamic aldehyde (Lilial), a widely used fragrance compound not present in the fragrance...
Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity
Pospori, Andreas; Marques, C. A. F.; Saez-Rodriguez, D.
An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors......, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β-transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force...... sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors....
Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.
An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β -transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors.
The contact angle of wetting of the solid phase of soil before and after chemical modification
Tyugai Zemfira
Full Text Available Wettability of soil affects a wide variety of processes including infiltration, preferential flow and surface runoff. Wettability of surface is usually expressed in terms of contact angle (CA measurement. If the CA between liquid and solid surface is less than 90°, the surface is called hydrophilic, otherwise the surface is called hydrophobic. If the CA of water droplet on hydrophilic surface is in a range of 0-30° this surface is called superhydrophilic. In case of superhydrophobic surfaces the CA exceeds 150° that means that these surfaces are extremely difficult to wet. CA of wetting of mineral soil particles depends on the overlying organic and iron compounds. The object of study is a sample of the humus-accumulative horizon of typical chernozem (Kursk, Russia and two samples (horizons A1, B2 of red ferrallitic soils (Fr. Norfolk, NE Oceania. The soil samples were analyzed for organic carbon, forms of non-silicate iron and hydrophobic-hydrophilic composition of humic substances. CA of wetting was determined in the intact samples and after removal of organic matter (H2O2 treatment, amorphous and crystallized forms of iron. Static contact angles were determined with the sessile drop method using a digital goniometer (Drop Shape Analysis System, DSA100, Krüss GmbH, Hamburg, Germany. The contact angle was calculated by the Young–Laplace method (fitting of Young–Laplace equation to the drop shape. The measurements were repeated 10-15 times for every sample. Oxidation of organic matter (H2O2 treatment causes an increase in the values of CA of wetting (in chernozem from 9.3 to 28,0-29.5º, in ferrallitic soil from 18.0 − 27.3 to 22.4 − 33.4º. CA remained constant for chernozem and slightly decreased in the case of ferrallitic soil, when the removal of amorphous and crystallized forms of iron was performed on samples pretreated with H2O2. CA increase occurs after successive removal of nonsilicate forms of iron from soil samples of
Sevoflurane anaesthesia for nasal surgery in a patient with multiple chemical sensitivity.
Fernández Martín, M T; �lvarez López, J C
Multiple chemical sensitivity syndrome is a group of complex disorders that include psychiatric disorders, chronic fatigue and/or respiratory problems. This syndrome could be triggered by specific allergens and toxins that cause neurophysiological sensitization and the appearance of the clinical symptomatology. Anaesthesia for these patients always poses a challenge for the anaesthetist, because they need to find and use drugs that do not trigger or aggravate the symptoms of the disease. Therefore, sevoflurane in these circumstances might be "the ideal anaesthetic". Performing general anaesthesia with sevoflurane as the sole anaesthetic agent, together with a series of environmental measures formed the basis for successful anaesthesia and surgery in our patient with a multiple chemical sensitivity syndrome. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.
Electroconvulsive therapy substantially reduces symptom severity and social disability associated with multiple chemical sensitivity: a case report
Elberling, Jesper; Gulmann, Nils; Rasmussen, Alice
Multiple chemical sensitivity (MCS) is a chronic nonallergic, multisymptom disorder triggered by common environmental chemicals in concentrations considered nontoxic for most individuals. The condition may lead to loss of occupation and social isolation, and no effective treatment has been reported...
Sesquiterpene lactone mix as a diagnostic tool for Asteraceae allergic contact dermatitis: chemical explanation for its poor performance and Sesquiterpene lactone mix II as a proposed improvement.
Jacob, Mathias; Brinkmann, Jürgen; Schmidt, Thomas J
Two preparations are currently in use for the diagnosis of allergic contact dermatitis caused by Asteraceae: (i) Sesquiterpene lactone (SL) mix [three pure sesquiterpene lactones (STLs)], whose use has been questioned, owing to an insufficient rate of true-positive results; and (ii) Compositae mix, consisting of five Asteraceae extracts, which is problematic because of lack of standardization and questionable reproducibility. To analyse the reasons for the narrow sensitivity of SL mix from a chemoinformatic point of view, and to propose a solution by rational selection of alternative constituents for a new SL mix II covering a broader cohort of allergic patients. Structural and biological information on allergenic STLs was retrieved from databases and the literature, and molecular modelling and chemoinformatic computations were performed. An explanation for the insufficient hit rate of SL mix is that the three constituents possess extremely similar molecular structures/properties and do not represent well the structural diversity of allergenic STLs. STLs that are known as constituents of Compositae mix plants show much a wider diversity, which explains the higher positive rate. On the basis of their positions in chemical property space, a new collection of STLs that more evenly cover the overall structural diversity spectrum is proposed. SL mix II is likely to detect a larger number of patients sensitized to Asteraceae. © 2012 John Wiley & Sons A/S.
An improvement of LLNA:DA to assess the skin sensitization potential of chemicals.
Zhang, Hongwei; Shi, Ying; Wang, Chao; Zhao, Kangfeng; Zhang, Shaoping; Wei, Lan; Dong, Li; Gu, Wen; Xu, Yongjun; Ruan, Hongjie; Zhi, Hong; Yang, Xiaoyan
We developed a modified local lymph node assay based on ATP (LLNA:DA), termed the Two-Stage LLNA:DA, to further reduce the animal numbers in the identification of sensitizers. In the Two-Stage LLNA:DA procedure, 13 chemicals ranging from non-sensitizers to extreme sensitizers were selected. The first stage used reduced LLNA:DA (rLLNA:DA) to screen out sensitive chemicals. The second stage used LLNA:DA based on OECD 442 (A) to classify those potential sensitizers screened out in the first stage. In the first stage, the SIs of the methyl methacrylate, salicylic acid, methyl salicylate, ethyl salicylate, isopropanol and propanediol were below 1.8 and need not to be tested in the second step. Others continued to be tested by LLNA:DA. In the second stage, sodium lauryl sulphate and xylene were classified as weak sensitizers. a-hexyl cinnamic aldehyde and eugenol were moderate sensitizers. Benzalkonium chloride and glyoxal were strong sensitizers, and phthalic anhydride was an extreme sensitizer. The 9/9, 11/12, 10/11, and 8/13 (positive or negative only) categories of the Two-Stage LLNA:DA were consistent with those from the other methods (LLNA, LLNA:DA, GPMT/BT and HMT/HPTA), suggesting that Two-Stage LLNA:DA have a high coincidence rate with reported data. In conclusion, The Two-Stage LLNA:DA is in line with the "3R" rules, and can be a modification of LLNA:DA but needs more study.
Ultraviolet laser ablation of fluorine-doped tin oxide thin films for dye-sensitized back-contact solar cells
Yang, Huan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Fu, Dongchuan [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia); Jiang, Ming [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Duan, Jun, E-mail: duans@hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Zhang, Fei; Zeng, Xiaoyan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Bach, Udo [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia)
In this study, laser ablation of a fluorine-doped tin oxide (FTO) thin film on a glass substrate was conducted using a 355 nm Nd:YVO{sub 4} ultraviolet (UV) laser to obtain a 4 × 4 mm microstructure. The microstructure contains a symmetric set of interdigitated FTO finger electrodes of a monolithic back-contact dye-sensitized solar cell (BC-DSC) on a common substrate. The effects of UV laser ablation parameters (such as laser fluence, repetition frequency, and scanning speed) on the size precision and quality of the microstructure were investigated using a 4 × 4 orthogonal design and an assistant experimental design. The incident photon-to-electron conversion efficiency and the current–voltage characteristics of the BC-DSC base of the interdigitated FTO finger electrodes were also determined. The experimental results show that an FTO film microstructure with high precision and good quality can be produced on a glass substrate via laser ablation with high scanning speed, high repetition frequency, and appropriate laser fluence. - Highlights: ► The ablation width and depth generally depend on the laser fluence. ► The scanning speed and the repetition frequency must match each other. ► Slight ablation of the glass substrate can completely remove F-doped tin oxide.
A national population study of the prevalence of multiple chemical sensitivity.
Caress, Stanley M; Steinemann, Anne C
The authors conducted a telephone survey of 1054 randomly selected individuals within the continental United States to determine the prevalence of chemical hypersensitivity and the medical diagnosis of multiple chemical sensitivity (MCS) in the American population. The etiology and symptomatology of MCS also were investigated. Results produced a 95% confidence level and a +/-3% margin of error. The authors found that 11.2% of Americans reported an unusual hypersensitivity to common chemical products such as perfume, fresh paint, pesticides, and other petrochemical-based substances, and 2.5% reported they had been medically diagnosed with MCS. Additionally, 31.1% of those sampled reported adverse reactions to fragranced products, and 17.6% experienced breathing difficulties and other health problems when exposed to air fresheners. Although chemical hypersensitivity was more common in women, it affected individuals in all demographic groups studied.
Micro-light-emitting diodes with III–nitride tunnel junction contacts grown by metalorganic chemical vapor deposition
Hwang, David
Micro-light-emitting diodes (µLEDs) with tunnel junction (TJ) contacts were grown entirely by metalorganic chemical vapor deposition. A LED structure was grown, treated with UV ozone and hydrofluoric acid, and reloaded into the reactor for TJ regrowth. The silicon doping level of the n++-GaN TJ was varied to examine its effect on voltage. µLEDs from 2.5 × 10−5 to 0.01 mm2 in area were processed, and the voltage penalty of the TJ for the smallest µLED at 20 A/cm2 was 0.60 V relative to that for a standard LED with indium tin oxide. The peak external quantum efficiency of the TJ LED was 34%.
Hwang, David; Mughal, Asad J.; Wong, Matthew S.; Alhassan, Abdullah I.; Nakamura, Shuji; DenBaars, Steven P.
Quantitative Genome-Wide Analysis of Yeast Deletion Strain Sensitivities to Oxidative and Chemical Stress
Stanley Fields
Full Text Available Understanding the actions of drugs and toxins in a cell is of critical importance to medicine, yet many of the molecular events involved in chemical resistance are relatively uncharacterized. In order to identify the cellular processes and pathways targeted by chemicals, we took advantage of the haploid Saccharomyces cerevisiae deletion strains (Winzeler et al., 1999. Although ~4800 of the strains are viable, the loss of a gene in a pathway affected by a drug can lead to a synthetic lethal effect in which the combination of a deletion and a normally sublethal dose of a chemical results in loss of viability. WE carried out genome-wide screens to determine quantitative sensitivities of the deletion set to four chemicals: hydrogen peroxide, menadione, ibuprofen and mefloquine. Hydrogen peroxide and menadione induce oxidative stress in the cell, whereas ibuprofen and mefloquine are toxic to yeast by unknown mechanisms. Here we report the sensitivities of 659 deletion strains that are sensitive to one or more of these four compounds, including 163 multichemicalsensitive strains, 394 strains specific to hydrogen peroxide and/or menadione, 47 specific to ibuprofen and 55 specific to mefloquine.We correlate these results with data from other large-scale studies to yield novel insights into cellular function.
Endocrine disrupting chemicals and other substances of concern in food contact materials: an updated review of exposure, effect and risk assessment.
Muncke, Jane
Food contact materials (FCM) are an underestimated source of chemical food contaminants and a potentially relevant route of human exposure to endocrine disrupting chemicals (EDCs). Quantifying the exposure of the general population to substances from FCM relies on estimates of food consumption and leaching into food. Recent studies using polycarbonate plastics show that food simulants do not always predict worst-case leaching of bisphenol A, a common FCM substance. Also, exposure of children to FCM substances is not always realistically predicted using the common conventions and thus possibly misjudged. Further, the exposure of the whole population to substances leaching into dry foods is underestimated. Consumers are exposed to low levels of substances from FCM across their entire lives. Effects of these compounds currently are assessed with a focus on mutagenicity and genotoxicity. This approach however neglects integrating recent new toxicological findings, like endocrine disruption, mixture toxicity, and developmental toxicity. According to these new toxicology paradigms women of childbearing age and during pregnancy are a new sensitive population group requiring more attention. Furthermore, in overweight and obese persons a change in the metabolism of xenobiotics is observed, possibly implying that this group of consumers is insufficiently protected by current risk assessment practice. Innovations in FCM risk assessment should therefore include routine testing for EDCs and an assessment of the whole migrate toxicity of a food packaging, taking into account all sensitive population groups. In this article I focus on recent issues of interest concerning either exposure to or effects of FCM-related substances. Further, I review the use of benzophenones and organotins, two groups of known or suspected EDCs, in FCM authorized in the US and EU. Copyright © 2010 Elsevier Ltd. All rights reserved.
Comparative sensitivity of human and rat neural cultures to chemical-induced inhibition of neurite outgrowth
Harrill, Joshua A.; Freudenrich, Theresa M.; Robinette, Brian L.; Mundy, William R., E-mail: mundy.william@epa.gov
There is a need for rapid, efficient and cost-effective alternatives to traditional in vivo developmental neurotoxicity testing. In vitro cell culture models can recapitulate many of the key cellular processes of nervous system development, including neurite outgrowth, and may be used as screening tools to identify potential developmental neurotoxicants. The present study compared primary rat cortical cultures and human embryonic stem cell-derived neural cultures in terms of: 1) reproducibility of high content image analysis based neurite outgrowth measurements, 2) dynamic range of neurite outgrowth measurements and 3) sensitivity to chemicals which have been shown to inhibit neurite outgrowth. There was a large increase in neurite outgrowth between 2 and 24 h in both rat and human cultures. Image analysis data collected across multiple cultures demonstrated that neurite outgrowth measurements in rat cortical cultures were more reproducible and had higher dynamic range as compared to human neural cultures. Human neural cultures were more sensitive than rat cortical cultures to chemicals previously shown to inhibit neurite outgrowth. Parallel analysis of morphological (neurite count, neurite length) and cytotoxicity (neurons per field) measurements were used to detect selective effects on neurite outgrowth. All chemicals which inhibited neurite outgrowth in rat cortical cultures did so at concentrations which did not concurrently affect the number of neurons per field, indicating selective effects on neurite outgrowth. In contrast, more than half the chemicals which inhibited neurite outgrowth in human neural cultures did so at concentrations which concurrently decreased the number of neurons per field, indicating that effects on neurite outgrowth were secondary to cytotoxicity. Overall, these data demonstrate that the culture models performed differently in terms of reproducibility, dynamic range and sensitivity to neurite outgrowth inhibitors. While human neural
Harrill, Joshua A.; Freudenrich, Theresa M.; Robinette, Brian L.; Mundy, William R.
Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor
Ma, Chunrui [Univ. of Texas, San Antonio, TX (United States); Enriquez, Erik [Univ. of Texas, San Antonio, TX (United States); Wang, Haibing [Univ. of Texas, San Antonio, TX (United States); Xu, Xing [Univ. of Texas, San Antonio, TX (United States); Bao, Shangyong [Univ. of Texas, San Antonio, TX (United States); Collins, Gregory [Univ. of Texas, San Antonio, TX (United States)
The research has been focused to design, fabricate, and develop high temperature/high sensitivity novel multifunctional chemical sensors for the selective detection of fossil energy gases used in power and fuel systems. By systematically studying the physical properties of the LnBaCo2O5+d (LBCO) [Ln=Pr or La] thin-films, a new concept chemical sensor based high temperature chemical resistant change has been developed for the application for the next generation highly efficient and near zero emission power generation technologies. We also discovered that the superfast chemical dynamic behavior and an ultrafast surface exchange kinetics in the highly epitaxial LBCO thin films. Furthermore, our research indicates that hydrogen can superfast diffuse in the ordered oxygen vacancy structures in the highly epitaxial LBCO thin films, which suggest that the LBCO thin film not only can be an excellent candidate for the fabrication of high temperature ultra sensitive chemical sensors and control systems for power and fuel monitoring systems, but also can be an excellent candidate for the low temperature solid oxide fuel cell anode and cathode materials.
Thermodynamic approach to the conditions of chemical deposition of boron by contact with an inert substrate
Thebault, J.; Naslain, R.; Hagenmuller, P.; Bernard, C.
The optimum conditions for the synthesis of boron by chemical vapour deposition (CVD) from BCl 3 -H 2 or BBr 3 -H 2 mixtures onto an inert substrate (boron or boronized metals) have been studied by a thermodynamic approach. This approach, which postulates that states close to equilibrium are reached in the vicinity of the hot substrate, is based on the minimization of the total Gibbs free energy of the system. Between 1200 and 1900 K and under a total pressure of 1 atm, the hydrogen reduction of BCl 3 can lead to two types of by-products: BHCl 2 at all temperatures, and BCl 2 or BCl subhalides at high temperatures; BHCl 2 is the main product of the reduction at the lowest temperatures. The hydrogen reduction of BCl 3 is never complete for the conditions commonly used for the synthesis of boron. The amount of by-products and of BBr 3 which must be recycled can be minimized by utilizing BCl 3 -H 2 mixtures rich in hydrogen. The amount of boron deposited exhibits a maximum for a temperature close to 1700 K. Similar results have been obtained for BBr 3 . However, between 1000 and 1500 K and under a total pressure of 1 atm the amount of by-products (BHBr 2 and BBr 2 ) is smaller than in the case of BCl 3 . The boron yield from the reduction of BBr 3 is higher than that from BCl 3 and the percentage of boron halide which must be recycled is lower in the case of BBr 3 . Thus, BBr 3 appears to be a better source than BCl 3 for the CVD of boron. (Auth.)
The potential pathogenicity of chlorhexidine-sensitive Acanthamoeba strains isolated from contact lens cases from asymptomatic individuals in Tenerife, Canary Islands, Spain.
Martín-Navarro, Carmen M; Lorenzo-Morales, Jacob; Cabrera-Serra, M Gabriela; Rancel, Fernando; Coronado-Alvarez, Nieves M; Piñero, José E; Valladares, Basilio
Pathogenic strains of the genus Acanthamoeba are causative agents of a serious sight-threatening infection of the eye known as Acanthamoeba keratitis. The prevalence of this infection has risen in the past 20 years, mainly due to the increase in number of contact lens wearers. In this study, the prevalence of Acanthamoeba in a risk group constituted by asymptomatic contact lens wearers from Tenerife, Canary Islands, Spain, was evaluated. Contact lenses and contact lens cases were analysed for the presence of Acanthamoeba isolates. The isolates' genotypes were also determined after rDNA sequencing. The pathogenic potential of the isolated strains was subsequently established using previously described molecular and biochemical assays, which allowed the selection of three strains with high pathogenic potential. Furthermore, the sensitivity of these isolates against two standard drugs, ciprofloxacin and chlorhexidine, was analysed. As the three selected strains were sensitive to chlorhexidine, its activity and IC(50) were evaluated. Chlorhexidine was found to be active against these strains and the obtained IC(50) values were compared to the concentrations of this drug present in contact lens maintenance solutions. It was observed that the measured IC(50) was higher than the concentration found in these maintenance solutions. Therefore, the ineffectiveness of chlorhexidine-containing contact lens maintenance solutions against potentially pathogenic strains of Acanthamoeba is demonstrated in this study.
Controlled assembly of organic whispering-gallery-mode microlasers as highly sensitive chemical vapor sensors.
Gao, Miaomiao; Wei, Cong; Lin, Xianqing; Liu, Yuan; Hu, Fengqin; Zhao, Yong Sheng
We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.
Inflammatory Mediator Profiling of n-butanol Exposed Upper Airways in Individuals with Multiple Chemical Sensitivity
Dantoft, Thomas Meinertz; Skovbjerg, Sine; Andersson, Linus
Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by reports of recurrent symptoms in response to low level exposure to various chemical substances. Recent findings suggests that dysregulation of the immune system may play a role in MCS pathophysiology. The aim of this study...... inflammatory mediator profiles (P>0.05) at baseline. Likewise, direct comparison of mediator levels in the MCS group and controls after n-butanol exposure revealed no significant group differences. We demonstrate no abnormal upper airway inflammatory mediator levels in MCS subjects before or after a symptom...
HMOX1 and NQO1 genes are upregulated in response to contact sensitizers in dendritic cells and THP-1 cell line: role of the Keap1/Nrf2 pathway.
Ade, Nadège; Leon, Fanny; Pallardy, Marc; Peiffer, Jean-Luc; Kerdine-Romer, Saadia; Tissier, Marie-Hélène; Bonnet, Pierre-Antoine; Fabre, Isabelle; Ourlin, Jean-Claude
Electrophilicity is one of the most common features of skin contact sensitizers and is necessary for protein haptenation. The Keap1 (Kelch-like ECH-associated protein 1)/Nrf2 -signaling pathway is dedicated to the detection of electrophilic stress in cells leading to the upregulation of genes involved in protection or neutralization of chemical reactive species. Signals provided by chemical stress could play an important role in dendritic cell activation and the aim of this work was to test whether contact sensitizers were specific activators of the Keap1/Nrf2 pathway. CD34-derived dendritic cells (CD34-DC) and the THP-1 myeloid cell line were treated by a panel of sensitizers (Ni, 1-chloro 2,4-dinitrobenzene, cinnamaldehyde, 7-hydroxycitronellal, 1,4-dihydroquinone, alpha-methyl-trans-cinnamaldehyde, 2-4-tert-(butylbenzyl)propionaldehyde or Lilial, and 1,4-phenylenediamine), irritants (sodium dodecyl sulfate, benzalkonium chloride), and a nonsensitizer molecule (chlorobenzene). Three well-known Nrf2 activators (tert-butylhydroquinone, lipoic acid, sulforaphane) were also tested. Expression of hmox1 and nqo1 was measured using real-time PCR and cellular accumulation of Nrf2 was assessed by Western blot. Our results showed an increased expression at early time points of hmox1 and nqo1 mRNAs in response to sensitizers but not to irritants. Accumulation of the Nrf2 protein was also observed only with chemical sensitizers. A significant inhibition of the expression of hmox1 and nqo1 mRNAs and CD86 expression was found in 1-chloro 2,4-dinitrobenzene-treated THP-1 cells preincubated with N-acetyl cysteine, a glutathione precursor. Altogether, these data suggested that the Keap1/Nrf2-signaling pathway was activated by electrophilic molecules including sensitizers in dendritic cells and in the THP-1 cell line. Monitoring of this pathway may provide new biomarkers (e.g., Nrf2, hmox1) for the detection of the sensitization potential of chemicals.
Auxetic Foam-Based Contact-Mode Triboelectric Nanogenerator with Highly Sensitive Self-Powered Strain Sensing Capabilities to Monitor Human Body Movement
Zhang, Steven L.; Lai, Ying-Chih; He, Xu; Liu, Ruiyuan; Zi, Yunlong; Wang, Zhong Lin
The first contact-mode triboelectric self-powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self-powered scale to measure weight, and a seat belt to measure body movements inside a car seat.
Zhang, Steven L.
The Influences of Face Inversion and Facial Expression on Sensitivity to Eye Contact in High-Functioning Adults with Autism Spectrum Disorders
Vida, Mark D.; Maurer, Daphne; Calder, Andrew J.; Rhodes, Gillian; Walsh, Jennifer A.; Pachai, Matthew V.; Rutherford, M. D.
We examined the influences of face inversion and facial expression on sensitivity to eye contact in high-functioning adults with and without an autism spectrum disorder (ASD). Participants judged the direction of gaze of angry, fearful, and neutral faces. In the typical group only, the range of directions of gaze leading to the perception of eye…
An 8.68% efficiency chemically-doped-free graphene-silicon solar cell using silver nanowires network buried contacts.
Yang, Lifei; Yu, Xuegong; Hu, Weidan; Wu, Xiaolei; Zhao, Yan; Yang, Deren
Graphene-silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.
Control of peptide nanotube diameter by chemical modifications of an aromatic residue involved in a single close contact
Tarabout, Christophe; Roux, Stéphane; Gobeaux, Frédéric; Fay, Nicolas; Pouget, Emilie; Meriadec, Cristelle; Ligeti, Melinda; Thomas, Daniel; IJsselstijn, Maarten; Besselievre, François; Buisson, David-Alexandre; Verbavatz, Jean-Marc; Petitjean, Michel; Valéry, Céline; Perrin, Lionel; Rousseau, Bernard; Artzner, Franck; Paternostre, Maité; Cintrat, Jean-Christophe
Supramolecular self-assembly is an attractive pathway for bottom-up synthesis of novel nanomaterials. In particular, this approach allows the spontaneous formation of structures of well-defined shapes and monodisperse characteristic sizes. Because nanotechnology mainly relies on size-dependent physical phenomena, the control of monodispersity is required, but the possibility of tuning the size is also essential. For self-assembling systems, shape, size, and monodispersity are mainly settled by the chemical structure of the building block. Attempts to change the size notably by chemical modification usually end up with the loss of self-assembly. Here, we generated a library of 17 peptides forming nanotubes of monodisperse diameter ranging from 10 to 36Â nm. A structural model taking into account close contacts explains how a modification of a few â"« of a single aromatic residue induces a fourfold increase in nanotube diameter. The application of such a strategy is demonstrated by the formation of silica nanotubes of various diameters. PMID:21518895
Highly Sensitive Bulk Silicon Chemical Sensors with Sub-5 nm Thin Charge Inversion Layers.
Fahad, Hossain M; Gupta, Niharika; Han, Rui; Desai, Sujay B; Javey, Ali
There is an increasing demand for mass-producible, low-power gas sensors in a wide variety of industrial and consumer applications. Here, we report chemical-sensitive field-effect-transistors (CS-FETs) based on bulk silicon wafers, wherein an electrostatically confined sub-5 nm thin charge inversion layer is modulated by chemical exposure to achieve a high-sensitivity gas-sensing platform. Using hydrogen sensing as a "litmus" test, we demonstrate large sensor responses (>1000%) to 0.5% H 2 gas, with fast response (<60 s) and recovery times (<120 s) at room temperature and low power (<50 μW). On the basis of these performance metrics as well as standardized benchmarking, we show that bulk silicon CS-FETs offer similar or better sensing performance compared to emerging nanostructures semiconductors while providing a highly scalable and manufacturable platform.
Suitability of macrophage inflammatory protein-1beta production by THP-1 cells in differentiating skin sensitizers from irritant chemicals.
Lim, Yeon-Mi; Moon, Seong-Joon; An, Su-Sun; Lee, Soo-Jin; Kim, Seo-Young; Chang, Ih-Seop; Park, Kui-Lea; Kim, Hyoung-Ah; Heo, Yong
Worldwide restrictions in animal use for research have driven efforts to develop alternative methods. The study aimed to test the efficacy of the macrophage inflammatory protein-1beta (MIP-1beta) assay for testing chemicals' skin-sensitizing capacity. The assay was performed using 9 chemicals judged to be sensitizing and 7 non-sensitizing by the standard in vivo assays. THP-1 cells were cultured in the presence or absence of 4 doses, 0.01x, 0.1x, 0.5x, or 1x IC(50) (50% inhibitory concentration for THP-1 cell proliferation) of these chemicals for 24 hr, and the MIP-1beta level in the supernatants was determined. Skin sensitization by the test chemicals was determined by MIP-1beta production rates. The MIP-1beta production rate was expressed as the relative increase in MIP-1beta production in response to chemical treatment compared with vehicle treatment. When the threshold MIP-1beta production rate used was 100% or 105% of dimethyl sulfoxide, all the sensitizing chemicals tested (dinitrochlorobenzene, hexyl cinnamic aldehyde, eugenol, hydroquinone, dinitrofluorobenzene, benzocaine, nickel, chromium, and 5-chloro-2-methyl-4-isothiazolin-3-one) were positive, and all the non-sensitizing chemicals (methyl salicylate, benzalkonium chloride, lactic acid, isopropanol, and salicylic acid), with the exception of sodium lauryl sulfate, were negative for MIP-1beta production. These results indicate that MIP-1beta could be a biomarker for classification of chemicals as sensitizers or non-sensitizers.
The local lymph node assay: current position in the regulatory classification of skin sensitizing chemicals.
Basketter, David A; Gerberick, G Frank; Kimber, Ian
The local lymph node assay (LLNA) is being used increasingly in the identification of skin sensitizing chemicals for regulatory purposes. In the context of new chemicals legislation (REACH) in Europe, it is the preferred assay. The rationale for this is that the LLNA quantitative and objective approach to skin sensitization testing allied with the important animal welfare benefits that the method offers. However, as with certain guinea pig sensitization tests before it, this increasing use also brings experience with an increasingly wide range of industrial and other chemicals where the outcome of the assay does not always necessarily meet with the expectations of those conducting it. Sometimes, the result appears to be a false negative, but rather more commonly, the complaint is that the chemical represents a false positive. Against this background we have here reviewed a number of instances where false positive and false negative results have been described and have sought to reconcile science with expectation. Based on these analyses, it is our conclusion that false positives and false negatives do occur in the LLNA, as they do with any other skin sensitization assay (and indeed with all tests used for hazard identification), and that this occurs for a number of reasons. We further conclude, however, that false positive results in the LLNA, as with the guinea pig maximization test, arise most commonly via failure to distinguish what is scientifically correct from that which is unpalatable. The consequences of this confusion are discussed in the article, particularly in relation to the need to integrate both potency measurement and risk assessments into classification and labelling schemes that aim to manage potential risks to human health.
Application of rat mast cell incubates as a possible short-time test for sensitizing occupational chemicals
Diel, F.; Neidhart, B.; Opree, W.
The direct action of sensitizing occupational chemicals (formaldehyde, phenol, phenylhydrazine, p-aminophenol) on rat mast cells was investigated by determination of histamine using HPLC separation and fluorimetric detection. It turned out that dispersed mast cells from immunized and non-immunized Wistar-rats are more sensitive than small-cut lung tissue slices. Passive cutaneous anaphylaxis was negative after a fortnight sensitizing experiment with the here described occupational chemicals. Short-time tests with rat mast cells reflect anaphylactoid response and are suitable for the screening of sensitizing chemicals.
Chemically Designed Metallic/Insulating Hybrid Nanostructures with Silver Nanocrystals for Highly Sensitive Wearable Pressure Sensors.
Kim, Haneun; Lee, Seung-Wook; Joh, Hyungmok; Seong, Mingi; Lee, Woo Seok; Kang, Min Su; Pyo, Jun Beom; Oh, Soong Ju
With the increase in interest in wearable tactile pressure sensors for e-skin, researches to make nanostructures to achieve high sensitivity have been actively conducted. However, limitations such as complex fabrication processes using expensive equipment still exist. Herein, simple lithography-free techniques to develop pyramid-like metal/insulator hybrid nanostructures utilizing nanocrystals (NCs) are demonstrated. Ligand-exchanged and unexchanged silver NC thin films are used as metallic and insulating components, respectively. The interfaces of each NC layer are chemically engineered to create discontinuous insulating layers, i.e., spacers for improved sensitivity, and eventually to realize fully solution-processed pressure sensors. Device performance analysis with structural, chemical, and electronic characterization and conductive atomic force microscopy study reveals that hybrid nanostructure based pressure sensor shows an enhanced sensitivity of higher than 500 kPa -1 , reliability, and low power consumption with a wide range of pressure sensing. Nano-/micro-hierarchical structures are also designed by combining hybrid nanostructures with conventional microstructures, exhibiting further enhanced sensing range and achieving a record sensitivity of 2.72 × 10 4 kPa -1 . Finally, all-solution-processed pressure sensor arrays with high pixel density, capable of detecting delicate signals with high spatial selectivity much better than the human tactile threshold, are introduced.
Evaluation of selected biomarkers for the detection of chemical sensitization in human skin: a comparative study applying THP-1, MUTZ-3 and primary dendritic cells in culture.
Hitzler, Manuel; Bergert, Antje; Luch, Andreas; Peiser, Matthias
Dendritic cells (DCs) exhibit the unique capacity to induce T cell differentiation and proliferation, two processes that are crucially involved in allergic reactions. By combining the exclusive potential of DCs as the only professional antigen-presenting cells of the human body with the well known handling advantages of cell lines, cell-based alternative methods aimed at detecting chemical sensitization in vitro commonly apply DC-like cells derived from myeloid cell lines. Here, we present the new biomarkers programmed death-ligand 1 (PD-L1), DC immunoreceptor (DCIR), IL-16, and neutrophil-activating protein-2 (NAP-2), all of which have been detectable in primary human DCs upon exposure to chemical contact allergens. To evaluate the applicability of DC-like cells in the prediction of a chemical's sensitization potential, the expression of cell surface PD-L1 and DCIR was analyzed. In contrast to primary DCs, only minor subpopulations of MUTZ-3 and THP-1 cells presented PD-L1 or DCIR at their surface. After exposure to increasing concentrations of nickel and cinnamic aldehyde, the expression level of PD-L1 and DCIR revealed much stronger affected on monocyte-derived DCs (MoDCs) or Langerhans cells (MoLCs) when compared to THP-1 and MUTZ-3 cells. Applying protein profiler arrays we further identified the soluble factors NAP-2, IL-16, IL-8 and MIP-1α as sensitive biomarkers showing the capacity to discriminate sensitizing from non-sensitizing chemicals or irritants. An allergen-specific release of IL-8 and MIP-1α could be detected in the supernatants of MoDCs and MoLCs and also in MUTZ-3 and THP-1 cells, though at much lower levels. On the protein and transcriptional level, NAP-2 and IL-16 indicated sensitizers most sensitively and specifically in MoDCs. Altogether, we have proven the reciprocal regulated surface molecules PD-L1 and DCIR and the soluble factors MIP-1α, NAP-2 and IL-16 as reliable biomarkers for chemical sensitization. We further show that primary
Rapid and sensitive reporter gene assays for detection of antiandrogenic and estrogenic effects of environmental chemicals
Vinggaard, Anne; Jørgensen, E.C.B.; Larsen, John Christian
Reports on increasing incidences in developmental abnormalities of the human male reproductive tract and the recent identifications of environmental chemicals with antiandrogenic activity necessitate the screening of a larger number of compounds in order to get an overview of potential antiandrog......Reports on increasing incidences in developmental abnormalities of the human male reproductive tract and the recent identifications of environmental chemicals with antiandrogenic activity necessitate the screening of a larger number of compounds in order to get an overview of potential...... antiandrogenic chemicals present in our environment. Thus, there is a great need for an effective in vitro screening method for (anti)androgenic chemicals. We have developed a rapid, sensitive, and reproducible reporter gene assay for detection of antiandrogenic chemicals. Chinese Hamster Ovary cells were...... calcium phosphate transfection method, this method has the advantage of being more feasible, as the assay can be scaled down to the microtiter plate format. Furthermore, the transfection reagent is noncytotoxic, allowing its addition together with the test compounds thereby reducing the hands...
Sickness-related dysfunction in persons with self-reported multiple chemical sensitivity at four levels of severity.
Gibson, Pamela Reed; Vogel, Valerie M
To examine quality of life outcome for persons who self-report chemical sensitivity, often referred to as multiple chemical sensitivity. Multiple chemical sensitivity is poorly understood with few providers specialising in its treatment. This lack of treatment and the ubiquity of chemicals engender severe life impacts such as job loss, financial loss, social isolation and even homelessness for persons who experience these sensitivities. Survey. We examined chemical incitants, symptoms and sickness-related behavioural dysfunction as measured by the Sickness Impact Profile in 254 persons self-identified with multiple chemical sensitivity. Chemicals rated as causing the most symptomatology in respondents were pesticide, formaldehyde, fresh paint, new carpet, diesel exhaust, perfume and air fresheners. The five highest rated symptoms in this sample were tiredness/lethargy, difficulty concentrating, muscle aches, memory difficulties and long-term fatigue. Overall mean Sickness Impact Profile score was 25.25%, showing serious impairment, with the most serious dysfunction in the categories of work (55.36%), alertness behaviour (53.45%) and recreation and pastimes (45.20%). Multiple chemical sensitivity is an important health care issue because it often includes serious dysfunction, is poorly understood by providers and poses extensive financial and treatment obstacles for those who experience it. Persons with multiple chemical sensitivity seek medical treatment in a variety of contexts and informed providers can both avoid iatrogenic harm due to medical exposures and provide any possible treatment for the chemical sensitivities. Understanding the impact of the health condition is crucial to communicate with and treat persons who experience the sensitivities.
High Sensitivity, Low Power Nano Sensors and Devices for Chemical Sensing
Li, Jing; Powell, Dan; Getty, Stephanie; Lu, Yi-Jiang
The chemical sensor market has been projected to grow to better than $40 billion dollars worldwide within the next 10 years. Some of the primary motivations to develop nanostructured chemical sensors are monitoring and control of environmental pollution; improved diagnostics for consumption; improvement in measurement precision and accuracy; and improved detection limits for Homeland security, battlefield environments, and process and quality control of industrial applications. In each of these applications, there is demand for sensitivity, selectivity and stability of environmental and biohazard detection and capture beyond what is currently commercially available. Nanotechnology offers the ability to work at the molecular level, atom by atom, to create large structures with fundamentally new molecular organization. It is essentially concerned with materials, devices, and systems whose structures and components exhibit novel and significantly improved physical, chemical and biological properties, phenomena, and process control due to their nanoscale size. One such nanotechnology-enabled chemical sensor has been developed at NASA Ames leveraging nanostructures, such as single walled carbon nanotubes (SWNTs) and metal oxide nanobelts or nanowires, as a sensing medium bridging a pair of interdigitated electrodes (IDE) realized through a silicon-based microfabrication and micromachining technique. The DE fingers are fabricated on a silicon substrate using standard photolithography and thin film metallization techniques. It is noteworthy that the fabrication techniques employed are not confined to the silicon substrate. Through spin casting and careful substrate selection (i.e. clothing, glass, polymer, etc.), additional degrees of freedom can be exploited to enhance sensitivity or to conform to unique applications. Both in-situ growth of nanostructured materials and casting of nanostructured dispersions were used to produce analogous chemical sensing devices.
Windows of sensitivity to toxic chemicals in the motor effects development.
Ingber, Susan Z; Pohl, Hana R
Many chemicals currently used are known to elicit nervous system effects. In addition, approximately 2000 new chemicals introduced annually have not yet undergone neurotoxicity testing. This review concentrated on motor development effects associated with exposure to environmental neurotoxicants to help identify critical windows of exposure and begin to assess data needs based on a subset of chemicals thoroughly reviewed by the Agency for Toxic Substances and Disease Registry (ATSDR) in Toxicological Profiles and Addenda. Multiple windows of sensitivity were identified that differed based on the maturity level of the neurological system at the time of exposure, as well as dose and exposure duration. Similar but distinct windows were found for both motor activity (GD 8-17 [rats], GD 12-14 and PND 3-10 [mice]) and motor function performance (insufficient data for rats, GD 12-17 [mice]). Identifying specific windows of sensitivity in animal studies was hampered by study designs oriented towards detection of neurotoxicity that occurred at any time throughout the developmental process. In conclusion, while this investigation identified some critical exposure windows for motor development effects, it demonstrates a need for more acute duration exposure studies based on neurodevelopmental windows, particularly during the exposure periods identified in this review. Published by Elsevier Inc.
Novel chemically cross-linked solid state electrolyte for dye-sensitized solar cells
Yin Xiong; Tan Weiwei; Xiang Wangchun; Lin Yuan; Zhang Jingbo; Xiao Xurui; Li Xueping; Zhou Xiaowen; Fang Shibi
Poly(vinylpyridine-co-ethylene glycol methyl ether methacrylate) (P(VP-co-MEOMA)) and α,ω-diiodo poly(ethylene oxide-co-propylene oxide) (I[(EO) 0.8 -co-(PO) 0.2 ] y I) were synthesized and used as chemically cross-linked precursors of the electrolyte for dye-sensitized solar cells. Meanwhile, α-iodo poly(ethylene oxide-co-propylene oxide) methyl ether (CH 3 O[(EO) 0.8 -co-(PO) 0.2 ] x I) was synthesized and added into the electrolyte as an internal plasticizer. Novel polymer electrolyte resulting from chemically cross-linked precursors was obtained by the quaterisation at 90 o C for 30 min. The characteristics for this kind of electrolyte were investigated by means of ionic conductivity, thermogravimetric and photocurrent-voltage. The ambient ionic conductivity was significantly enhanced to 2.3 x 10 -4 S cm -1 after introducing plasticizer, modified-ionic liquid. The weight loss of the solid state electrolyte at 200 o C was 1.8%, and its decomposition temperature was 287 o C. Solid state dye-sensitized solar cell based on chemically cross-linked electrolyte presented an overall conversion efficiency of 2.35% under AM1.5 irradiation (100 mW cm -2 ). The as-fabricated device maintained 88% of its initial performance at room temperature even without sealing for 30 days, showing a good stability.
Color stability, radiopacity, and chemical characteristics of white mineral trioxide aggregate associated with 2 different vehicles in contact with blood.
Guimarães, Bruno Martini; Tartari, Talita; Marciano, Marina Angélica; Vivan, Rodrigo Ricci; Mondeli, Rafael Francisco Lia; Camilleri, Josette; Duarte, Marco Antonio Hungaro
Discoloration of mineral trioxide aggregate (MTA) can be exacerbated by the interaction of the cement with body fluids such as blood. This study aimed to analyze the color alteration, chemical characteristics, and radiopacity of MTA manipulated with 2 different vehicles after immersion in blood or distilled water (DW). MTA mixed with 100% DW or 80% DW/20% propylene glycol (PG) as vehicles were placed into rubber rings and incubated at 37°C and 100% relative humidity until set. Color assessment and scanning electron microscopy/energy-dispersive spectroscopy analysis were performed after setting and repeated after 7, 15, and 30 days after immersion in blood and DW. Statistical analysis for color alteration and radiopacity was performed using nonparametric Kruskal-Wallis and Dunn tests (P vehicle, significantly lower color alterations were observed for all time periods compared with 100% DW when immersed in blood (P media because of loss of bismuth. A decrease in radiopacity was observed over time in all groups, with a statistically significant difference after 30 days for groups DW immersed in blood and 80% DW/20% immersed in both media (P vehicle for MTA results in a lower color alteration when in contact with blood. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Research on removing reservoir core water sensitivity using the method of ultrasound-chemical agent for enhanced oil recovery.
Wang, Zhenjun; Huang, Jiehao
The phenomenon of water sensitivity often occurs in the oil reservoir core during the process of crude oil production, which seriously affects the efficiency of oil extraction. In recent years, near-well ultrasonic processing technology attaches more attention due to its safety and energy efficient. In this paper, the comparison of removing core water sensitivity by ultrasonic wave, chemical injection and ultrasound-chemical combination technique are investigated through experiments. Results show that: lower ultrasonic frequency and higher power can improve the efficiency of core water sensitivity removal; the effects of removing core water sensitivity under ultrasonic treatment get better with increase of core initial permeability; the effect of removing core water sensitivity using ultrasonic treatment won't get better over time. Ultrasonic treatment time should be controlled in a reasonable range; the effect of removing core water sensitivity using chemical agent alone is slightly better than that using ultrasonic treatment, however, chemical injection could be replaced by ultrasonic treatment for removing core water sensitivity from the viewpoint of oil reservoir protection and the sustainable development of oil field; ultrasound-chemical combination technique has the best effect for water sensitivity removal than using ultrasonic treatment or chemical injection alone. Copyright © 2017 Elsevier B.V. All rights reserved.
Chemical cross-linking with thiol-cleavable reagents combined with differential mass spectrometric peptide mapping--a novel approach to assess intermolecular protein contacts
Bennett, K L; Kussmann, M; Björk, P
The intermolecular contact regions between monomers of the homodimeric DNA binding protein ParR and the interaction between the glycoproteins CD28 and CD80 were investigated using a strategy that combined chemical cross-linking with differential MALDI-MS analyses. ParR dimers were modified in vit...
Investigating the effect of silicon surface chemical treatment on Al/Si contact properties in GaP/Si solar cells
Kudryashov, D.; Gudovskikh, A.
In the present work, experimental studies have been carried out to reveal how chemical treatment of a silicon surface affects the properties of the Al/Si contact. It has been shown that for p-type monocrystalline silicon substrates with a resistivity of 10 ohm cm, it is possible to form an ohmic Al/Si contact by magnetron sputtering of an aluminum thin film and its further annealing at temperatures of 400 - 450 °C. In the range of annealing temperatures of 250 - 400 °C, the Si substrate treatment in the HF solution leads to a significant increase in currents on the current-voltage curves of the Al/Si contact, while in the range of 450 - 700 °C, the effect of chemical treatment of the silicon is not detected.
Physico-chemical mechanism for the vapors sensitivity of photoluminescent InP quantum dots
Prosposito, P.; De Angelis, R.; De Matteis, F.; Hatami, F.; Masselink, W. T.; Zhang, H.; Casalboni, M.
InP/InGaP surface quantum dots are interesting materials for optical chemical sensors since they present an intense emission at room temperature, whose intensity changes rapidly and reversibly depending on the composition of the environmental atmosphere. We present here their emission properties by time resolved photoluminescence spectroscopy investigation and we discuss the physico-chemical mechanism behind their sensitivity to the surrounding atmosphere. Photoluminescence transients in inert atmosphere (N2) and in solvent vapours of methanol, clorophorm, acetone and water were measured. The presence of vapors of clorophorm, acetone and water showed a very weak effect on the transient times, while an increase of up to 15% of the decay time was observed for methanol vapour exposure. On the basis of the vapor molecule nature (polarity, proticity, steric hindrance, etc.) and of the interaction of the vapor molecules with the quantum dots surface a sensing mechanism involving quantum dots non-radiative surface states is proposed.
Prosposito, P.; De Angelis, R.; De Matteis, F.; Casalboni, M.; Hatami, F.; Masselink, W.T.; Zhang, H.
InP/InGaP surface quantum dots are interesting materials for optical chemical sensors since they present an intense emission at room temperature, whose intensity changes rapidly and reversibly depending on the composition of the environmental atmosphere. We present here their emission properties by time resolved photoluminescence spectroscopy investigation and we discuss the physico-chemical mechanism behind their sensitivity to the surrounding atmosphere. Photoluminescence transients in inert atmosphere (N 2 ) and in solvent vapours of methanol, chloroform, acetone and water were measured. The presence of vapors of chloroform, acetone and water showed a very weak effect on the transient times, while an increase of up to 15% of the decay time was observed for methanol vapour exposure. On the basis of the vapor molecule nature (polarity, proticity, steric hindrance, etc.) and of the interaction of the vapor molecules with the quantum dots surface a sensing mechanism involving quantum dots non-radiative surface states is proposed. (paper)
Two-Dimensional Photonic Crystals for Sensitive Microscale Chemical and Biochemical Sensing
Miller, Benjamin L.
Photonic crystals – optical devices able to respond to changes in the refractive index of a small volume of space – are an emerging class of label-free chemical-and bio-sensors. This review focuses on one class of photonic crystal, in which light is confined to a patterned planar material layer of sub-wavelength thickness. These devices are small (on the order of tens to 100s of microns square), suitable for incorporation into lab-on-a-chip systems, and in theory can provide exceptional sensitivity. We introduce the defining characteristics and basic operation of two-dimensional photonic crystal sensors, describe variations of their basic design geometry, and summarize reported detection results from chemical and biological sensing experiments. PMID:25563402
Experimental assessment of the sensitiveness of an electrochemical oscillator towards chemical perturbations.
Graziela C A Ferreira
Full Text Available In this study we address the problem of the response of a (electrochemical oscillator towards chemical perturbations of different magnitudes. The chemical perturbation was achieved by addition of distinct amounts of trifluoromethanesulfonate (TFMSA, a rather stable and non-specifically adsorbing anion, and the system under investigation was the methanol electro-oxidation reaction under both stationary and oscillatory regimes. Increasing the anion concentration resulted in a decrease in the reaction rates of methanol oxidation and a general decrease in the parameter window where oscillations occurred. Furthermore, the addition of TFMSA was found to decrease the induction period and the total duration of oscillations. The mechanism underlying these observations was derived mathematically and revealed that inhibition in the methanol oxidation through blockage of active sites was found to further accelerate the intrinsic non-stationarity of the unperturbed system. Altogether, the presented results are among the few concerning the experimental assessment of the sensitiveness of an oscillator towards chemical perturbations. The universal nature of the complex chemical oscillator investigated here might be used for reference when studying the dynamics of other less accessible perturbed networks of (biochemical reactions.
Effect of genes controlling radiation sensitivity on chemically induced mutations in Saccharomyces cerevisiae
Prakash, L.
The effect of 16 different genes (rad) conferring radiation sensitivity on chemically induced reversion in the yeast Saccharomyces cerevisiae was determined. The site of reversion used was a well-defined chain initiation mutant mapping in the structural gene coding for iso-1-cytochrome c. High doses of EMS and HNO 2 resulted in decreased reversion of cyc1-131 in rad6, rad9 and rad15 strains compared to the normal RAD + strains. In addition, rad52 greatly decreased EMS reversion of cyc1-131 but had no effect on HNO 2 -induced reversion; rad18, on the other hand, increased HNO 2 -induced reversion but did not alter EMS-induced reversion. When NQO was used as the mutagen, every rad gene tested, except for rad18, had an effect on reversion; rad6, rad9, rad15, rad17, rad18, rad22, rev1, rev2, and rev3 lowered NQO reversion while rad1, rad2, rad3, rad4, rad10, rad12, and rad16 increased it compared to the RAD + strain. The effect of rad genes on chemical mutagenesis is discussed in terms of their effect on uv mutagenesis. It is concluded that although the nature of the repair pathways may differ for uv- and chemically-induced mutations in yeast, a functional repair system is required for the induction of mutation by the chemical agents NQO, EMS, and HNO 2
Improving the photovoltaic parameters in Quantum dot sensitized solar cells through employment of chemically deposited compact titania blocking layer
Rajendra Prasad, M.B., E-mail: rajendraprasadmb75@gmail.com [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); National Defence Academy, Khadakwasla, Pune, 411023 (India); Kadam, Vishal [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); Joo, Oh-Shim [Korea Institute of Science and Technology, PO Box No. 131, Chongryang, Seoul, 130-650 (Korea, Republic of); Pathan, Habib M. [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India)
Incorporation of compact blocking layer at the Transparent Conducting Oxide (TCO)/Electrolyte interface is an effective method to improve the device performance in QDSSC through mitigation of electron recombinations at this interface. This paper reports the most facile and cost effective method of depositing a rutile titania Compact Layer (CL) over Fluorine doped Tin Oxide (FTO) substrate and its application in titania based CdS QD sensitized solar cells. The deposited compact layers are characterized to study their structural, optical, morphological and electrochemical properties using X-Ray Diffractometry, UV–Visible spectroscopy, Scanning electron microscopy, Cyclic Voltammetry and Contact Angle measurements. Sandwich solar cells are fabricated using these CL based electrodes and characterized using Electrochemical Impedance Spectroscopy, Open Circuit Voltage Decay and J-V characteristics. The CL incorporated CdS QDSSC showed more than 100% increase in the photoconversion efficiency (1.68%) as compared to its bare FTO counterpart (0.73%) proving the efficacy of employed strategy. - Highlights: • Deposited titania compact layer by a facile room temperature chemical bath method. • Employed this to mitigate back electron transfer at TCO/Electrolyte interface. • Compact layer incorporation has improved the solar cell performance by 130%.
Enhanced expression of IL-8 in normal human keratinocytes and human keratinocyte cell line HaCaT in vitro after stimulation with contact sensitizers, tolerogens and irritants.
Mohamadzadeh, M; Müller, M; Hultsch, T; Enk, A; Saloga, J; Knop, J
To investigate the interleukin-8 production of keratinocytes after stimulation in vitro we have used various agents: (i) contact sensitizer (2,4-dinitrofluorobenzene, 3-n-pentadecylcatechol); (ii) tolerogen (5-methyl-3-n-pentadecylcatechol); (iii) irritant (sodium lauryl sulfate). Interleukin-8 gene expression was assessed by northern blot hybridization of the total cytoplasmic RNA extracted from subconfluent normal human keratinocyte cultures and the keratinocyte cell line HaCaT using a radiolabeled DNA probe specific for human interleukin-8. Interleukin-8 gene expression was markedly increased upon in vitro stimulation after 1-6 h with contact sensitizers, tolerogen and the irritant. In contrast, interleukin-8 production was not detectable in unstimulated normal human keratinocytes or the HaCaT keratinocyte cell line. These results suggest that the induction and production of interleukin-8 is a response to nonspecific stimuli and may play a critical role in the early response to immunogenic or inflammatory signals in man.
Psychogenic chemical sensitivity: psychogenic pseudoseizures elicited by provocation challenges with fragrances.
Staudenmayer, H; Kramer, R E
A middle-aged woman with a 10-year history of disability attributed to chemical sensitivities complained that exposure to specific fragrances immediately elicited seizures. Video-EEG monitoring was performed in a hospital neurodiagnostic laboratory during provocative challenge studies employing fragrances identified by the patient as reliably inducing symptoms. The baseline clinical EEG was normal. Immediately after each provocation with air deodorant and perfume, she consistently showed both generalized tonic/clonic and multifocal myoclonic jerking, at times was nonresponsive, spoke with slurred speech, and complained of right-sided paralysis and lethargy. None of these events were associated with any EEG abnormalities. Psychological assessment (MMPI-2, MCMI-II) revealed personality traits that predisposed her to somatization and beliefs about environmental sensitivities. The convulsions were a manifestation of psychogenic pseudoseizures that had been iatrogenically reinforced.
Highly sensitive methanol chemical sensor based on undoped silver oxide nanoparticles prepared by a solution method
Rahman, M.M.; Khan, S.B.; Asiri, A.M.; Jamal, A.; Faisal, M.
We have prepared silver oxide nanoparticles (NPs) by a simple solution method using reducing agents in alkaline medium. The resulting NPs were characterized by UV-vis and FT-IR spectroscopy, X-ray powder diffraction, and field-emission scanning electron microscopy. They were deposited on a glassy carbon electrode to give a sensor with a fast response towards methanol in liquid phase. The sensor also displays good sensitivity and long-term stability, and enhanced electrochemical response. The calibration plot is linear (r 2 = 0.8294) over the 0.12 mM to 0.12 M methanol concentration range. The sensitivity is ∼ 2.65 μAcm -2 mM -1 , and the detection limit is 36.0 μM (at a SNR of 3). We also discuss possible future prospective uses of this metal oxide semiconductor nanomaterial in terms of chemical sensing. (author)
Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic.
Khan, Muhammad Shar Jhahan; Wang, Ya-Wen; Senge, Mathias O; Peng, Yu
Two highly sensitive probes bearing a nucleophilic imine moiety have been utilized for the selective detection of chemical warfare agent (CWA) mimics. Diethyl chlorophosphate (DCP) was used as mimic CWAs. Both iminocoumarin-benzothiazole-based probes not only demonstrated a remarkable fluorescence ON-OFF response and good recognition, but also exhibited fast response times (10s) along with color changes upon addition of DCP. Limits of detection for the two sensors 1 and 2 were calculated as 0.065μM and 0.21μM, respectively, which are much lower than most other reported probes. These two probes not only show high sensitivity and selectivity in solution, but can also be applied for the recognition of DCP in the gas state, with significant color changes easily observed by the naked eye. Copyright © 2017 Elsevier B.V. All rights reserved.
Evaluation of Doped Phthalocyanines and a Chemically-Sensitive Field Effect Transistor for Detecting Nitrogen Dioxide
exposure. Muller, et al., attempted to correct a problem with their simple arrays. With a simple array, each individual detector within the array would be...tna! relates fundamental material and geometrica ! considerations in the development of a chemically-sensitive microsensor based upon the IGEFET. Also...MEASUREMENT 5600 P-RINT * 5650 PRINT "SET-UP THE ELECTROMETER FOR ZERO CORRECT " 5660 INPUT 'ENTER RETURN WHEN READY", M'ULL$ 5700 S$="F1" 'SET 10 MEASURE
Occupation, exposure to chemicals, sensitizing agents, and risk of multiple myeloma in Sweden.
Lope, Virginia; Pérez-Gómez, Beatriz; Aragonés, Nuria; López-Abente, Gonzalo; Gustavsson, Per; Plato, Nils; Zock, Jan-Paul; Pollán, Marina
This study sought to identify occupations with high incidence of multiple myeloma and to investigate possible excess risk associated with occupational exposure to chemicals and sensitizing agents in Sweden. A historical cohort of 2,992,166 workers was followed up (1971--1989) through record linkage with the National Cancer and Death Registries. For each job category, age and period standardized incidence ratios and age and period adjusted relative risks of multiple myeloma were calculated using Poisson models. Exposure to chemicals and to sensitizing agents was also assessed using two job-exposure matrices. Men and women were analyzed separately. During follow-up, 3,127 and 1,282 myelomas were diagnosed in men and women, respectively. In men, excess risk was detected among working proprietors, agricultural, horticultural and forestry enterprisers, bakers and pastry cooks, dental technicians, stone cutters/carvers, and prison/reformatory officials. In women, this excess was observed among attendants in psychiatric care, metal workers, bakers and pastry cooks, and paper/paperboard product workers. Workers, particularly bakers and pastry cooks, exposed to high molecular weight sensitizing agents registered an excess risk of over 40% across the sexes. Occasional, although intense, exposure to pesticides was also associated with risk of myeloma in our cohort. Our study supports a possible etiologic role for farming and use of pesticides in myeloma risk. The high incidence found in both female and male bakers and pastry cooks has not been described previously. Further research is required to assess the influence of high molecular weight sensitizing agents on risk of multiple myeloma.
Repeated monthly epicutaneous challenges with diphenylcyclopropenone result in a clinically reproducible level of contact allergy in de novo sensitized individuals
Mose, K. F.; Andersen, F.; Skov, L
Diphenylcyclopropenone (DPCP) has been used as an experimental contact allergen in humans and for topical immunotherapy of patients with alopecia areata. However, the efficacy is mostly based on case series. Randomized controlled clinical trials are lacking(1) , as is detailed descriptions of how...... repeated topical exposure to DPCP affect the level of hypersensitivity. This article is protected by copyright. All rights reserved.......Diphenylcyclopropenone (DPCP) has been used as an experimental contact allergen in humans and for topical immunotherapy of patients with alopecia areata. However, the efficacy is mostly based on case series. Randomized controlled clinical trials are lacking(1) , as is detailed descriptions of how...
Incidence of allergic contact sensitization in Danish adults between 1990 and 1998; the Copenhagen Allergy Study, Denmark
Nielsen, N H; Linneberg, A; Menné, T
factors for developing contact allergy in an adult general population sample. PATIENTS AND METHODS: In 1990 a random sample of 567 persons of the 15-69-year-old population living in the western part of Copenhagen County (Denmark) was patch tested in a cross-sectional study. In 1998 a follow-up study...... of these women had bought the eliciting item in Denmark before 1995, when vigorous control of the Danish nickel legislation was introduced. CONCLUSIONS: We found a considerable number of incident cases of contact allergy in the adult population. The results of the study support the actions taken to restrict...
Sensitivity enhancement of chemically amplified resists and performance study using extreme ultraviolet interference lithography
Buitrago, Elizabeth; Nagahara, Seiji; Yildirim, Oktay; Nakagawa, Hisashi; Tagawa, Seiichi; Meeuwissen, Marieke; Nagai, Tomoki; Naruoka, Takehiko; Verspaget, Coen; Hoefnagels, Rik; Rispens, Gijsbert; Shiraishi, Gosuke; Terashita, Yuichi; Minekawa, Yukie; Yoshihara, Kosuke; Oshima, Akihiro; Vockenhuber, Michaela; Ekinci, Yasin
Extreme ultraviolet lithography (EUVL, λ=13.5 nm) is the most promising candidate to manufacture electronic devices for future technology nodes in the semiconductor industry. Nonetheless, EUVL still faces many technological challenges as it moves toward high-volume manufacturing (HVM). A key bottleneck from the tool design and performance point of view has been the development of an efficient, high-power EUV light source for high throughput production. Consequently, there has been extensive research on different methodologies to enhance EUV resist sensitivity. Resist performance is measured in terms of its ultimate printing resolution, line width roughness (LWR), sensitivity [S or best energy (BE)], and exposure latitude (EL). However, there are well-known fundamental trade-off relationships (line width roughness, resolution and sensitivity trade-off) among these parameters for chemically amplified resists (CARs). We present early proof-of-principle results for a multiexposure lithography process that has the potential for high sensitivity enhancement without compromising other important performance characteristics by the use of a "Photosensitized Chemically Amplified Resist™" (PSCAR™). With this method, we seek to increase the sensitivity by combining a first EUV pattern exposure with a second UV-flood exposure (λ=365 nm) and the use of a PSCAR. In addition, we have evaluated over 50 different state-of-the-art EUV CARs. Among these, we have identified several promising candidates that simultaneously meet sensitivity, LWR, and EL high-performance requirements with the aim of resolving line space (L/S) features for the 7- and 5-nm logic node [16- and 13-nm half-pitch (HP), respectively] for HVM. Several CARs were additionally found to be well resolved down to 12- and 11-nm HP with minimal pattern collapse and bridging, a remarkable feat for CARs. Finally, the performance of two negative tone state-of-the-art alternative resist platforms previously investigated
Preparation and investigation of burried metal/molecule contact interfaces with surface sensitive methods; Praeparation und Untersuchung verborgener Metall/Molekuel-Kontaktgrenzflaechen mit oberflaechensensitiven Methoden
Vrdoljak, Pavo
The present thesis establishes an optimised concept of a delamination technique suitable for ultra high vacuum (UHV) with which model systems of buried interfaces were made accessible for surface sensitive methods which were applied to investigate their electronic and topographical properties. A primary focus of this work is on the question how buried interfaces could be accessed successfully for surface sensitive methods using buried metal/NTCDA and metal/PTCDA interfaces as model systems. Contacts of approximately 10 x 15 mm{sup 2} in size were accessed. The second focus of the thesis is on the investigation of the electronical and topographical properties of the buried interfaces, for which some similarities between delaminated metal (Au,Ag)/ PTCDA- and Ag/NTCDA interfaces were found: After the delamination of top-contacts there were inhomogeneous layers of molecules on the metal contacts. Whereas PTCDA covered metal contacts had thicker molecular layers (4-5 ML PTCDA on Ag), NTCDA covered contacts showed only one monolayer coverage over large areas of at least 2 mm in diameter. Regions with multilayer coverage showed smooth surfaces whereas metal surfaces showed a fissured, meander-like and rough surface. Both contact systems also had in common that the adhesive made PES investigations of valence states very difficult. Furthermore, it was possible to thin out the molecular layers thermally but afterwards no valence states could be measured. Investigating in-situ delaminated buried interfaces, the focus was on metal (Au,Ag)/PTCDA interfaces first. The molecular layers could be successfully desorbed thermally at 260 C to 1-3 monolayers so that valence states were investigated. The spectra of the in-situ delaminated and thermally desorbed Ag/PTCDA contact were noticeably broadened so that the positions of HOMO and FLUMO could only be estimated at 1.9 eV and 0.7 eV, respectively. Additionally, interfaces of Ag/NTCDA contacts were investigated. With UPS it was found
[Multiple chemical sensitivity: Clinical evaluation of the severity and psychopathological profile].
Lago Blanco, Eva; Puiguriguer Ferrando, Jordi; Rodríguez Enríquez, Mónica; Agüero Gento, Laura; Salvà Coll, Joan; Pizà Portell, Maria Rosa
Multiple chemical sensitivity (MCS) is a multisystem disorder of controversial etiology, affecting some subjects when exposed to chemicals at no harmful concentrations. The objective of this paper is to describe the epidemiological, clinical and psychological features of a sample of patients with MCS for further specific group treatment. Descriptive study of patients diagnosed with MCS in a toxicology unit. We administered the Quick Environmental Exposure and Sensitivity Inventory, the structured interview SCID-II, the anxiety scale HAS and the type A personality test, PCTA. Seventy-three patients were included. The mean age was 52,6 years (range 33-77; SD 9.29). Sixty-six were females (90.4%). Fifty-three percent were classified as i-ii and ii grade. Sixty-one patients (83%) presented some type of comorbidity, mainly chronic pain, fibromyalgia and chronic fatigue. They exhibited higher levels of anxiety (average score of 19.2), prevalence of phobic-avoidant traits of personality and type A behavior in 31.1%. MCS affects middle-aged women with comorbidities (chronic pain, fibromyalgia and chronic fatigue) and high anxiety and avoidance behaviors. This preliminary analysis should help provide a specific therapeutic approach to these patients. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.
Reduction and Uncertainty Analysis of Chemical Mechanisms Based on Local and Global Sensitivities
Esposito, Gaetano
Numerical simulations of critical reacting flow phenomena in hypersonic propulsion devices require accurate representation of finite-rate chemical kinetics. The chemical kinetic models available for hydrocarbon fuel combustion are rather large, involving hundreds of species and thousands of reactions. As a consequence, they cannot be used in multi-dimensional computational fluid dynamic calculations in the foreseeable future due to the prohibitive computational cost. In addition to the computational difficulties, it is also known that some fundamental chemical kinetic parameters of detailed models have significant level of uncertainty due to limited experimental data available and to poor understanding of interactions among kinetic parameters. In the present investigation, local and global sensitivity analysis techniques are employed to develop a systematic approach of reducing and analyzing detailed chemical kinetic models. Unlike previous studies in which skeletal model reduction was based on the separate analysis of simple cases, in this work a novel strategy based on Principal Component Analysis of local sensitivity values is presented. This new approach is capable of simultaneously taking into account all the relevant canonical combustion configurations over different composition, temperature and pressure conditions. Moreover, the procedure developed in this work represents the first documented inclusion of non-premixed extinction phenomena, which is of great relevance in hypersonic combustors, in an automated reduction algorithm. The application of the skeletal reduction to a detailed kinetic model consisting of 111 species in 784 reactions is demonstrated. The resulting reduced skeletal model of 37--38 species showed that the global ignition/propagation/extinction phenomena of ethylene-air mixtures can be predicted within an accuracy of 2% of the full detailed model. The problems of both understanding non-linear interactions between kinetic parameters and
Non-specific chemical inhibition of the Fanconi anemia pathway sensitizes cancer cells to cisplatin
Jacquemont Céline
Full Text Available Abstract Background Platinum compounds such as cisplatin and carboplatin are DNA crosslinking agents widely used for cancer chemotherapy. However, the effectiveness of platinum compounds is often tempered by the acquisition of cellular drug resistance. Until now, no pharmacological approach has successfully overcome cisplatin resistance in cancer treatment. Since the Fanconi anemia (FA pathway is a DNA damage response pathway required for cellular resistance to DNA interstrand crosslinking agents, identification of small molecules that inhibit the FA pathway may reveal classes of chemicals that sensitize cancer cells to cisplatin. Results Through a cell-based screening assay of over 16,000 chemicals, we identified 26 small molecules that inhibit ionizing radiation and cisplatin-induced FANCD2 foci formation, a marker of FA pathway activity, in multiple human cell lines. Most of these small molecules also compromised ionizing radiation-induced RAD51 foci formation and homologous recombination repair, indicating that they are not selective toward the regulation of FANCD2. These compounds include known inhibitors of the proteasome, cathepsin B, lysosome, CHK1, HSP90, CDK and PKC, and several uncharacterized chemicals including a novel proteasome inhibitor (Chembridge compound 5929407. Isobologram analyses demonstrated that half of the identified molecules sensitized ovarian cancer cells to cisplatin. Among them, 9 demonstrated increased efficiency toward FA pathway-proficient, cisplatin-resistant ovarian cancer cells. Six small molecules, including bortezomib (proteasome inhibitor, CA-074-Me (cathepsin B inhibitor and 17-AAG (HSP90 inhibitor, synergized with cisplatin specifically in FA-proficient ovarian cancer cells (2008 + FANCF, but not in FA-deficient isogenic cells (2008. In addition, geldanamycin (HSP90 inhibitor and two CHK1 inhibitors (UCN-01 and SB218078 exhibited a significantly stronger synergism with cisplatin in FA
SKIN SENSITIZATION AND ALLERGIC CONTACT DERMATITIS (BASIC COURSE): THE GLOBAL REGULATORY ENVIRONMENT - CONTINUING EDUCATION COURSE; 1 OF 4 SPEAKERS FOR AN SOT BASIC COURSE
New regulations have emerged in recent years giving guidance on how best to conduct skin sensitization testing on new chemical entities. For example, recently The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) in the U.S. and the European Ce...
Chemical biology drug sensitivity screen identifies sunitinib as synergistic agent with disulfiram in prostate cancer cells.
Kirsi Ketola
Full Text Available Current treatment options for castration- and treatment-resistant prostate cancer are limited and novel approaches are desperately needed. Our recent results from a systematic chemical biology sensitivity screen covering most known drugs and drug-like molecules indicated that aldehyde dehydrogenase inhibitor disulfiram is one of the most potent cancer-specific inhibitors of prostate cancer cell growth, including TMPRSS2-ERG fusion positive cancers. However, the results revealed that disulfiram alone does not block tumor growth in vivo nor induce apoptosis in vitro, indicating that combinatorial approaches may be required to enhance the anti-neoplastic effects.In this study, we utilized a chemical biology drug sensitivity screen to explore disulfiram mechanistic details and to identify compounds potentiating the effect of disulfiram in TMPRSS2-ERG fusion positive prostate cancer cells. In total, 3357 compounds including current chemotherapeutic agents as well as drug-like small molecular compounds were screened alone and in combination with disulfiram. Interestingly, the results indicated that androgenic and antioxidative compounds antagonized disulfiram effect whereas inhibitors of receptor tyrosine kinase, proteasome, topoisomerase II, glucosylceramide synthase or cell cycle were among compounds sensitizing prostate cancer cells to disulfiram. The combination of disulfiram and an antiangiogenic agent sunitinib was studied in more detail, since both are already in clinical use in humans. Disulfiram-sunitinib combination induced apoptosis and reduced androgen receptor protein expression more than either of the compounds alone. Moreover, combinatorial exposure reduced metastatic characteristics such as cell migration and 3D cell invasion as well as induced epithelial differentiation shown as elevated E-cadherin expression.Taken together, our results propose novel combinatorial approaches to inhibit prostate cancer cell growth. Disulfiram
Colored Contact Lens Dangers
Full Text Available ... Costume Contacts May Contain Chemicals Harmful to Eyes Four Ways Over-the-Counter Costume Contact Lenses Can ... was in severe pain and on medication for four weeks, and couldn't see well enough to ...
Sensitivity enhancement of chemically amplified resists and performance study using EUV interference lithography
Extreme ultraviolet lithography (EUVL, λ = 13.5 nm) is the most promising candidate to manufacture electronic devices for future technology nodes in the semiconductor industry. Nonetheless, EUVL still faces many technological challenges as it moves toward high-volume manufacturing (HVM). A key bottleneck from the tool design and performance point of view has been the development of an efficient, high power EUV light source for high throughput production. Consequently, there has been extensive research on different methodologies to enhance EUV resist sensitivity. Resist performance is measured in terms of its ultimate printing resolution, line width roughness (LWR), sensitivity (S or best energy BE) and exposure latitude (EL). However, there are well-known fundamental trade-off relationships (LRS trade-off) among these parameters for chemically amplified resists (CARs). Here we present early proof-of-principle results for a multi-exposure lithography process that has the potential for high sensitivity enhancement without compromising other important performance characteristics by the use of a Photosensitized Chemically Amplified Resist (PSCAR). With this method, we seek to increase the sensitivity by combining a first EUV pattern exposure with a second UV flood exposure (λ = 365 nm) and the use of a PSCAR. In addition, we have evaluated over 50 different state-of-the-art EUV CARs. Among these, we have identified several promising candidates that simultaneously meet sensitivity, LWR and EL high performance requirements with the aim of resolving line space (L/S) features for the 7 and 5 nm logic node (16 nm and 13 nm half-pitch HP, respectively) for HVM. Several CARs were additionally found to be well resolved down to 12 nm and 11 nm HP with minimal pattern collapse and bridging, a remarkable feat for CARs. Finally, the performance of two negative tone state-of-the-art alternative resist platforms previously investigated was compared to the CAR performance at and
Proteomic Signatures of the Zebrafish (Danio rerio) Embryo: Sensitivity and Specificity in Toxicity Assessment of Chemicals.
Hanisch, Karen; Küster, Eberhard; Altenburger, Rolf; Gündel, Ulrike
Studies using embryos of the zebrafish Danio rerio (DarT) instead of adult fish for characterising the (eco-) toxic potential of chemicals have been proposed as animal replacing methods. Effect analysis at the molecular level might enhance sensitivity, specificity, and predictive value of the embryonal studies. The present paper aimed to test the potential of toxicoproteomics with zebrafish eleutheroembryos for sensitive and specific toxicity assessment. 2-DE-based toxicoproteomics was performed applying low-dose (EC(10)) exposure for 48 h with three-model substances Rotenone, 4,6-dinitro-o-cresol (DNOC) and Diclofenac. By multivariate "pattern-only" PCA and univariate statistical analyses, alterations in the embryonal proteome were detectable in nonetheless visibly intact organisms and treatment with the three substances was distinguishable at the molecular level. Toxicoproteomics enabled the enhancement of sensitivity and specificity of the embryonal toxicity assay and bear the potency to identify protein markers serving as general stress markers and early diagnosis of toxic stress.
Process development for waveguide chemical sensors with integrated polymeric sensitive layers
Amberkar, Raghu; Gao, Zhan; Park, Jongwon; Henthorn, David B.; Kim, Chang-Soo
Due to the proper optical property and flexibility in the process development, an epoxy-based, high-aspect ratio photoresist SU-8 is now attracting attention in optical sensing applications. Manipulation of the surface properties of SU-8 waveguides is critical to attach functional films such as chemically-sensitive layers. We describe a new integration process to immobilize fluorescence molecules on SU-8 waveguide surface for application to intensity-based optical chemical sensors. We use two polymers for this application. Spin-on, hydrophobic, photopatternable silicone is a convenient material to contain fluorophore molecules and to pattern a photolithographically defined thin layer on the surface of SU-8. We use fumed silica powders as an additive to uniformly disperse the fluorophores in the silicone precursor. In general, additional processes are not critically required to promote the adhesion between the SU-8 and silicone. The other material is polyethylene glycol diacrylate (PEGDA). Recently we demonstrated a novel photografting method to modify the surface of SU-8 using a surface bound initiator to control its wettability. The activated surface is then coated with a monomer precursor solution. Polymerization follows when the sample is exposed to UV irradiation, resulting in a grafted PEGDA layer incorporating fluorophores within the hydrogel matrix. Since this method is based the UV-based photografting reaction, it is possible to grow off photolithographically defined hydrogel patterns on the waveguide structures. The resulting films will be viable integrated components in optical bioanalytical sensors. This is a promising technique for integrated chemical sensors both for planar type waveguide and vertical type waveguide chemical sensors.
Clinical update on contact allergy
Uter, Wolfgang; Johansen, Jeanne Duus; Orton, David I
PURPOSE OF REVIEW: The aim of this article is to review recent findings in contact allergy, regarding clinical research. RECENT FINDINGS: The biocide methyldibromo glutaronitrile was identified to be an important sensitizer. Subsequently, it was banned from leave-on cosmetics in the European Union...... a classification of newly introduced chemicals; increasingly, the local lymph node assay is supplementing and potentially replacing the guinea pig maximization test. Recent advances in occupational contact allergy include, for example, some attempts to improve diagnostics for epoxy resin and other plastic, glue...
Contrasting effects of ultraviolet-A and ultraviolet B exposure on induction of contact sensitivity in human skin
Skov, Lone; Hansen, Henrik; Barker, J. N.
Ultraviolet-B (UVB), in addition to direct effects on DNA, induces immunological changes in the skin that predispose to the development of skin cancer. Whether ultraviolet-A (UVA) induces similar changes is unknown. This effect can be investigated in humans in vivo using epicutaneous antigens...... as a model of tumour antigens. Volunteers (n = 46) were randomly assigned to received no sensitization, sensitization with the allergen diphenylcyclopropenone (DPCP) on non-UV-exposed normal skin, or sensitization with DPCP on skin exposed to three minimal erythema doses (MED) of either UVA or UVB radiation...... the immunization rate compared with sensitization on non-irradiated skin (P UVA radiation did not result in a decreased immunization rate compared with non-irradiated skin. These results indicate that in humans erythemagenic...
High sensitivity detection and characterization of the chemical state of trace element contamination on silicon wafers
Pianetta, Piero A; Baur, K; Brennan, S; Homma, T; Kubo, N
Increasing the speed and complexity of semiconductor integrated circuits requires advanced processes that put extreme constraints on the level of metal contamination allowed on the surfaces of silicon wafers. Such contamination degrades the performance of the ultrathin SiO sub 2 gate dielectrics that form the heart of the individual transistors. Ultimately, reliability and yield are reduced to levels that must be improved before new processes can be put into production. It should be noted that much of this metal contamination occurs during the wet chemical etching and rinsing steps required for the manufacture of integrated circuits and industry is actively developing new processes that have already brought the metal contamination to levels beyond the measurement capabilities of conventional analytical techniques. The measurement of these extremely low contamination levels has required the use of synchrotron radiation total reflection X-ray fluorescence (SR-TXRF) where sensitivities 100 times better than conv...
The contact-temperature ignition (CTI) criteria for propagating chemical reactions including the effect of moisture and application to Hanford waste
Cash, R.J.
To assure the continued absence of uncontrolled condensed-phase chemical reactions in connection with the Hanford waste materials, efforts have been underway including both theoretical and experimental investigations to clarify the requirements for such reactions. This document defines the differences and requirements for homogeneous runaway and propagating chemical reactions incuding a discussion of general contact-temperature ignition (CTI) condition for propagating reactions that include the effect of moisture. The CTI condition implies that the contact temperature or interface temperature between reacted and unreacted materials must exceed the ignition temperature and is compared to experimental data including both synthetic ferrocyanide and surrogate organic materials. In all cases, the occurrences of ignition accompanied by self-propagating reactions are consistent with the theoretical anticipations of the CTI condition
Evaluation of non-radioactive endpoints of ex vivo local lymph node assay-BrdU to investigate select contact sensitizers.
Ulker, Ozge Cemiloglu; Ates, Ilker; Atak, Aysegul; Karakaya, Asuman
The present study sought to verify the utility of the non-radioactive endpoints LLNA BrdU (5-bromo-2'-deoxyuridine) ex vivo incorporation and cytokine release using auricular lymph node cells isolated from BALB/c mice topically treated with a strong (formaldehyde or p-phenylene-diamine [PPD]), moderate sensitizer (cinnamal), or weak sensitizer (eugenol). Stimulation index (SI) and EC₃ values were calculated for each agent. Based on the results of ex vivo LLNA-BrdU assays, EC₃ values were calculated to be 0.29, 0.09, 1.91, and 16.60% for formaldehyde, PPD, cinnamal, and eugenol, respectively. These results were in good agreement with data from previous standard radioactive LLNA. Cytokine analyses indicated T(H)1 and T(H)2 cytokine involvement in the regulation of murine contact allergy and these could be utilized as endpoints in assessments of contact allergy in mice. In conclusion, the current study provided evidence that the non-radioactive endpoint LLNA BrdU ex vivo incorporation could be of use as a viable alternative approach to assess the skin sensitization potential of test compound with respect to improving animal welfare. This is of particular importance in the case of any laboratory where it might be difficult to handle and/or readily employ radioisotopes. Further studies will be required to confirm--across test agents--the reproducibility as well as the limits of utility of this new ex vivo BrdU method.
Uncertainty and sensitivity analysis: Mathematical model of coupled heat and mass transfer for a contact baking process
Feyissa, Aberham Hailu; Gernaey, Krist; Adler-Nissen, Jens
to uncertainty in the model predictions. The aim of the current paper is to address this uncertainty challenge in the modelling of food production processes using a combination of uncertainty and sensitivity analysis, where the uncertainty analysis and global sensitivity analysis were applied to a heat and mass......Similar to other processes, the modelling of heat and mass transfer during food processing involves uncertainty in the values of input parameters (heat and mass transfer coefficients, evaporation rate parameters, thermo-physical properties, initial and boundary conditions) which leads...
Debating the legitimacy of a contested environmental illness: a case study of multiple chemical sensitivities (MCS).
Phillips, Tarryn
More than 20years after it was first identified, the anomalous condition, multiple chemical sensitivities (MCS), remains immersed in controversy, with a continuing debate over its causation being played out in the medico-scientific community and in the courts. This article examines why sceptical and supportive experts disagree over the condition's legitimacy as an organic condition. Drawing on ethnographic research conducted in Perth, Western Australia, the author scrutinises the decision-making practices of 16 experts (eight sceptical and eight supportive of a chemical explanation). Both groups were found to use evidence-based, inductive reasoning. However, sceptical experts tended to use a different set of evidence requirements, exhibited more faith in the efficiency of the current biomedical paradigm regarding toxicity and were less likely to acknowledge uncertainty in their field. All the experts recognised a spectrum of beliefs about the causal mechanisms of MCS. However, when they were engaged in litigation as expert witnesses due to their supportive or sceptical tendency, the oppositional legal system polarised their opinions and exacerbated the perceived divide between them. Ultimately, the adversarial medico-legal process inhibits genuine dialogue between some of the key players in the MCS debate, thus impeding understanding and consensus about the condition. © 2010 The Author. Sociology of Health & Illness © 2010 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.
Highly sensitive fiber grating chemical sensors: An effective alternative to atomic absorption spectroscopy
Laxmeshwar, Lata. S.; Jadhav, Mangesh S.; Akki, Jyoti. F.; Raikar, Prasad; Kumar, Jitendra; prakash, Om; Raikar, U. S.
Accuracy in quantitative determination of trace elements like Zinc, present in drinking water in ppm level, is a big challenge and optical fiber gratings as chemical sensors may provide a promising solution to overcome the same. This paper presents design of two simple chemical sensors based on the principle of shift in characteristic wavelength of gratings with change in their effective refractive index, to measure the concentration of Zinc in drinking water using etched short period grating (FBG) and Long period grating (LPG) respectively. Three samples of drinking water from different places have been examined for presence of Zinc. Further, the results obtained by our sensors have also been verified with the results obtained by a standard method, Atomic absorption spectroscopy (AAS). The whole experiment has been performed by fixing the fibers in a horizontal position with the sensor regions at the center of the fibers, making it less prone to disturbance and breaking. The sensitivity of LPG sensor is about 205 times that of the FBG sensor. A few advantages of Fiber grating sensors, besides their regular features, over AAS have also been discussed, that make our sensors potential alternatives for existing techniques in determination of trace elements in drinking water.
Outbreak of contact sensitization to methylisothiazolinone: an analysis of French data from the REVIDAL-GERDA network.
Hosteing, Stéphanie; Meyer, Nicolas; Waton, Julie; Barbaud, Annick; Bourrain, Jean-Luc; Raison-Peyron, Nadia; Felix, Brigitte; Milpied-Homsi, Brigitte; Ferrier Le Bouedec, Marie-Christine; Castelain, Michel; Vital-Durand, Dominique; Debons, Michèle; Collet, Evelyne; Avenel-Audran, Martine; Mathelier-Fusade, Pascale; Vermeulen, Christophe; Assier, Haudrey; Gener, Gwendoline; Lartigau-Sezary, Isabelle; Catelain-Lamy, Amandine; Giordano-Labadie, Françoise
The preservative methylisothiazolinone (MI) is used in combination with methylchloroisothiazolinone (MCI), but the MCI/MI mixture has been identified as highly allergenic. MI is considered to be less allergenic, and since the mid-2000s has been widely used alone, but is now clearly identified as a contact allergen. The French Vigilance Network for Dermatology and Allergy of the Study and Research Group on Contact Dermatitis (REVIDAL-GERDA) added MI to its baseline patch testing series in 2010. To evaluate the change in the proportion of MI-positive tests in France between 2010 and 2012. We conducted a nationwide, multicentre, retrospective study of all MI-tested patients between 2010 and 2012. Sixteen centres participated in the study (7874 patients were tested). Patch tests were performed mainly at a concentration of MI 200 ppm aq. We observed a significant increase in the proportion of MI-positive tests in 2012 and 2011 as compared with 2010 (5.6%, 3.3%, and 1.5%, respectively; p
Sensitive detection of rutin based on {beta}-cyclodextrin-chemically reduced graphene/Nafion composite film
Liu Kunping; Wei Jinping [School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)
Highlights: > {beta}-CD-graphene composite obtained via a simple sonication-induced assembly. > Accelerating electron transfer on electrode to amplify the electrochemical signal. > A highly sensitive electrochemical sensor for rutin detection. > Good selectivity and reproducibility for the detection of rutin in real samples. - Abstract: An electrochemical sensor based on chemically reduced graphene (CRG) was developed for the sensitive detection of rutin. To construct the base of the sensor, a novel composite was initially fabricated and used as the substrate material by combining CRG and {beta}-cyclodextrin ({beta}-CD) via a simple sonication-induced assembly. Due to the high rutin-loading capacity on the electrode surface and the upstanding electric conductivity of graphene, the electrochemical response of the fabricated sensor was greatly enhanced and displayed excellent analytical performance for rutin detection from 6.0 x 10{sup -9} to 1.0 x 10{sup -5} mol L{sup -1} with a low detection limit of 2.0 x 10{sup -9} mol L{sup -1} at 3{sigma}. Moreover, the proposed electrochemical sensor also exhibited good selectivity and acceptable reproducibility and could be used for the detection of rutin in real samples. Therefore, the present work offers a new way to broaden the analytical applications of graphene in pharmaceutical analysis.
Extremely sensitive multiple sensing ring PCF sensor for lower indexed chemical detection
Veerpal Kaur
Full Text Available In this article, we have designed and analysed a photonic crystal fiber with multiple sensing ring in core for chemical and biochemical sensing applications. In this proposed design, three and four sensing ring describe in core which offers remarkable high sensitivity and spiral cladding pattern confines large fraction of power in core region and thus reduce the overall confinement loss. This novel proposed model exhibits simultaneously ultra high relative sensitivity 95.40%, 93.13% and minimum confinement loss 7.108×10−08, 2.47×10−08dB/km for four and three ring pattern. These sensing rings are filled with different sensing liquid. Multiple sensing rings as compared to multiple air holes are desirable feature from fabrication point of view. This proposed PCF design overcomes some experimental challenge such as PCF probe needs some displacement after filling the sensing liquid. These uniform circular sensing rings around the solid core overcome the losses and support better evanescent field matter interaction for sensing application. Multiple sensing rings as compared to multiple tiny air holes are desirable feature from fabrication point of view.
Correlation between chemical, crystallographic and spectroscopic parameters in graphite thermometry applied to a contact aureole of La Soledad monzogranite (Venezuelan Andes
K. Reategui
Full Text Available Graphite samples from a metamorphic contact aureole between phyllites of the Cerro Azul Association (Palaeozoic and La Soledad Monzogranite, in the Venezuelan Andes, were studied by chemical (% inorganic carbon and isotopic distribution, crystallographic (DRX and spectroscopic (Raman techniques in order to assess changes in the graphite in the vicinity of the contact, the correlation between the different parameters, and the determination of the higher temperature reached by the host rock during igneous intrusion. The δ13C reached less negative values near the monzogranite, caused by devolatilization; the graphite present just in contact with the pluton experienced retrograde recrystallization, which causes a shift towards more negative values. The calculated degree of graphitization intervals (GD = 53–80 corresponds to a well-structured mineral with ordered packaging. The peak metamorphic temperature at the contact was calculated from crystallographic (XRD and spectroscopic (Raman parameters with great agreement in both techniques, registering the 528 ± 16 and 526 ± 20 ºC respectively. The metapelitic rocks reached the Cordierite Zone (cordierite + biotite + muscovite in the contact aureole where the graphite is well ordered and in hexagonal microtexture. Factors such as fluid activity and the subsequent retrograde recrystallization have an effect on isotopic redistributions after the intrusive event, as well as on the crystallinity change rate with the temperature, avoiding a clear correlation between the isotopic variations of 13C in graphite and the temperature.
Linear chemically sensitive electron tomography using DualEELS and dictionary-based compressed sensing
AlAfeef, Ala, E-mail: a.al-afeef.1@research.gla.ac.uk [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); School of Computing Science, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Bobynko, Joanna [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Cockshott, W. Paul. [School of Computing Science, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Craven, Alan J. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Zuazo, Ian; Barges, Patrick [ArcelorMittal Maizières Research, Maizières-lès-Metz 57283 (France); MacLaren, Ian, E-mail: ian.maclaren@glasgow.ac.uk [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
We have investigated the use of DualEELS in elementally sensitive tilt series tomography in the scanning transmission electron microscope. A procedure is implemented using deconvolution to remove the effects of multiple scattering, followed by normalisation by the zero loss peak intensity. This is performed to produce a signal that is linearly dependent on the projected density of the element in each pixel. This method is compared with one that does not include deconvolution (although normalisation by the zero loss peak intensity is still performed). Additionally, we compare the 3D reconstruction using a new compressed sensing algorithm, DLET, with the well-established SIRT algorithm. VC precipitates, which are extracted from a steel on a carbon replica, are used in this study. It is found that the use of this linear signal results in a very even density throughout the precipitates. However, when deconvolution is omitted, a slight density reduction is observed in the cores of the precipitates (a so-called cupping artefact). Additionally, it is clearly demonstrated that the 3D morphology is much better reproduced using the DLET algorithm, with very little elongation in the missing wedge direction. It is therefore concluded that reliable elementally sensitive tilt tomography using EELS requires the appropriate use of DualEELS together with a suitable reconstruction algorithm, such as the compressed sensing based reconstruction algorithm used here, to make the best use of the limited data volume and signal to noise inherent in core-loss EELS. - Highlights: • DualEELS is essential for chemically sensitive electron tomography using EELS. • A new compressed sensing based algorithm (DLET) gives high fidelity reconstruction. • This combination of DualEELS and DLET will give reliable results from few projections.
THP-1 monocytes but not macrophages as a potential alternative for CD34+ dendritic cells to identify chemical skin sensitizers
Lambrechts, Nathalie; Verstraelen, Sandra; Lodewyckx, Hanne; Felicio, Ana; Hooyberghs, Jef; Witters, Hilda; Tendeloo, Viggo van; Cauwenberge, Paul van; Nelissen, Inge; Heuvel, Rosette van den; Schoeters, Greet
Early detection of the sensitizing potential of chemicals is an emerging issue for chemical, pharmaceutical and cosmetic industries. In our institute, an in vitro classification model for prediction of chemical-induced skin sensitization based on gene expression signatures in human CD34 + progenitor-derived dendritic cells (DC) has been developed. This primary cell model is able to closely mimic the induction phase of sensitization by Langerhans cells in the skin, but it has drawbacks, such as the availability of cord blood. The aim of this study was to investigate whether human in vitro cultured THP-1 monocytes or macrophages display a similar expression profile for 13 predictive gene markers previously identified in DC and whether they also possess a discriminating capacity towards skin sensitizers and non-sensitizers based on these marker genes. To this end, the cell models were exposed to 5 skin sensitizers (ammonium hexachloroplatinate IV, 1-chloro-2,4-dinitrobenzene, eugenol, para-phenylenediamine, and tetramethylthiuram disulfide) and 5 non-sensitizers (L-glutamic acid, methyl salicylate, sodium dodecyl sulfate, tributyltin chloride, and zinc sulfate) for 6, 10, and 24 h, and mRNA expression of the 13 genes was analyzed using real-time RT-PCR. The transcriptional response of 7 out of 13 genes in THP-1 monocytes was significantly correlated with DC, whereas only 2 out of 13 genes in THP-1 macrophages. After a cross-validation of a discriminant analysis of the gene expression profiles in the THP-1 monocytes, this cell model demonstrated to also have a capacity to distinguish skin sensitizers from non-sensitizers. However, the DC model was superior to the monocyte model for discrimination of (non-)sensitizing chemicals.
The impact of vehicle on the relative potency of skin-sensitizing chemicals in the local lymph node assay.
Jowsey, Ian R; Clapp, Catherine J; Safford, Bob; Gibbons, Ben T; Basketter, David A
The identification and characterization of chemicals that possess skin-sensitizing potential are typically performed using predictive tests. However, human exposure to skin-sensitizing chemicals often occurs via a matrix (vehicle) that differs from that used in these tests. It is thus important to account for the potential impact of vehicle differences when undertaking quantitative risk assessment for skin sensitization. This is achieved through the application of a specific sensitization assessment factor (SAF), scaled between 1 and 10, when identifying an acceptable exposure level. The objective of the analysis described herein is to determine the impact of vehicle differences on local lymph node assay (LLNA) EC3 values (concentrations of test chemical required to provoke a 3-fold increase in lymph node cell proliferation). Initially, the inherent variability of the LLNA was investigated by examining the reproducibility of EC3 values for 14 chemicals that have been tested more than once in the same vehicle (4:1 acetone:olive oil, AOO). This analysis reveals that the variability in EC3 value for these chemicals following multiple assessments is LLNA using at least 2 of 15 different vehicles. These data demonstrate that often the variability in EC3 values observed for a given chemical in different vehicles is no greater than the 5-fold inherent variability observed when assessing a chemical in the same vehicle on multiple occasions. However, there are examples where EC3 values for a chemical differ by a factor of more than 10 between different vehicles. These observations were often associated with an apparent underestimation of potency (higher EC3 values) with predominantly aqueous vehicles or propylene glycol. These data underscore the need to consider vehicle effects in the context of skin-sensitization risk assessments.
Sensitivity of transatlantic dust transport to chemical aging and related atmospheric processes
Abdelkader, Mohamed
We present a sensitivity study on transatlantic dust transport, a process which has many implications for the atmosphere, the ocean and the climate. We investigate the impact of key processes that control the dust outflow, i.e., the emission flux, convection schemes and the chemical aging of mineral dust, by using the EMAC model following Abdelkader et al. (2015). To characterize the dust outflow over the Atlantic Ocean, we distinguish two geographic zones: (i) dust interactions within the Intertropical Convergence Zone (ITCZ), or the dust–ITCZ interaction zone (DIZ), and (ii) the adjacent dust transport over the Atlantic Ocean (DTA) zone. In the latter zone, the dust loading shows a steep and linear gradient westward over the Atlantic Ocean since particle sedimentation is the dominant removal process, whereas in the DIZ zone aerosol–cloud interactions, wet deposition and scavenging processes determine the extent of the dust outflow. Generally, the EMAC simulated dust compares well with CALIPSO observations; however, our reference model configuration tends to overestimate the dust extinction at a lower elevation and underestimates it at a higher elevation. The aerosol optical depth (AOD) over the Caribbean responds to the dust emission flux only when the emitted dust mass is significantly increased over the source region in Africa by a factor of 10. These findings point to the dominant role of dust removal (especially wet deposition) in transatlantic dust transport. Experiments with different convection schemes have indeed revealed that the transatlantic dust transport is more sensitive to the convection scheme than to the dust emission flux parameterization. To study the impact of dust chemical aging, we focus on a major dust outflow in July 2009. We use the calcium cation as a proxy for the overall chemical reactive dust fraction and consider the uptake of major inorganic acids (i.e., H2SO4, HNO3 and HCl) and their anions, i.e., sulfate (SO42−), bisulfate
Seismic Wave Propagation from Underground Chemical Explosions: Sensitivity to Velocity and Thickness of a Weathered Layer
Hirakawa, E. T.; Ezzedine, S. M.
Recorded motions from underground chemical explosions are complicated by long duration seismic coda as well as motion in the tangential direction. The inability to distinguish the origins of these complexities as either source or path effects comprises a limitation to effective monitoring of underground chemical explosions. With numerical models, it is possible to conduct rigorous sensitivity analyses for chemical explosive sources and their resulting ground motions under the influence of many attributes, including but not limited to complex velocity structure, topography, and non-linear source characteristics. Previously we found that topography can cause significant scattering in the direct wave but leads to relatively little motion in the coda. Here, we aim to investigate the contribution from the low-velocity weathered layer that exists in the shallow subsurface apart from and in combination with surface topography. We use SW4, an anelastic anisotropic fourth order finite difference code to simulate chemical explosive source in a 1D velocity structure consisting of a single weathered layer over a half space. A range of velocity magnitudes are used for the upper weathered layer with the velocities always being lower than that of the granitic underlaying layer. We find that for lower weathered layer velocities, the wave train is highly dispersed and causes a large percentage of energy to be contained in the coda in relation to the entire time series. The percentage of energy contained in the coda grows with distance from the source but saturates at a certain distance that depends on weathered layer velocity and thickness. The saturation onset distance increases with decreasing layer thickness and increasing velocity of the upper layer. Measurements of relative coda energy and coda saturation onset distance from real recordings can provide an additional constraint on the properties of the weathered layer in remote sites as well as test sites like the Nevada
Chemical management in fungicide sensitivity of Mycosphaerella fijiensis collected from banana fields in México.
Aguilar-Barragan, Alejandra; García-Torres, Ana Elisa; Odriozola-Casas, Olga; Macedo-Raygoza, Gloria; Ogura, Tetsuya; Manzo-Sánchez, Gilberto; James, Andrew C; Islas-Flores, Ignacio; Beltrán-García, Miguel J
The chemical management of the black leaf streak disease in banana caused by Mycosphaerella fijiensis (Morelet) requires numerous applications of fungicides per year. However this has led to fungicide resistance in the field. The present study evaluated the activities of six fungicides against the mycelial growth by determination of EC50 values of strains collected from fields with different fungicide management programs: Rustic management (RM) without applications and Intensive management (IM) more than 25 fungicide application/year. Results showed a decreased sensitivity to all fungicides in isolates collected from IM. Means of EC50 values in mg L(-1) for RM and IM were: 13.25 ± 18.24 and 51.58 ± 46.14 for azoxystrobin, 81.40 ± 56.50 and 1.8575 ± 2.11 for carbendazim, 1.225 ± 0.945 and 10.01 ± 8.55 for propiconazole, 220 ± 67.66 vs. 368 ± 62.76 for vinclozolin, 9.862 ± 3.24 and 54.5 ± 21.08 for fludioxonil, 49.2125 ± 34.11 and 112.25 ± 51.20 for mancozeb. A molecular analysis for β-tubulin revealed a mutation at codon 198 in these strains having an EC50 greater than 10 mg L(-1) for carbendazim. Our data indicate a consistency between fungicide resistance and intensive chemical management in banana fields, however indicative values for resistance were also found in strains collected from rustic fields, suggesting that proximity among fields may be causing a fungus interchange, where rustic fields are breeding grounds for development of resistant strains. Urgent actions are required in order to avoid fungicide resistance in Mexican populations of M. fijiensis due to fungicide management practices.
Inflammatory Mediator Profiling of n-butanol Exposed Upper Airways in Individuals with Multiple Chemical Sensitivity.
Thomas Meinertz Dantoft
Full Text Available Multiple Chemical Sensitivity (MCS is a chronic condition characterized by reports of recurrent symptoms in response to low level exposure to various chemical substances. Recent findings suggests that dysregulation of the immune system may play a role in MCS pathophysiology.The aim of this study was to examine baseline and low dose n-butanol-induced upper airway inflammatory response profiles in MCS subjects versus healthy controls.Eighteen participants with MCS and 18 age- and sex-matched healthy controls were enrolled in the study. Epithelial lining fluid was collected from the nasal cavity at three time points: baseline, within 15 minutes after being exposed to 3.7 ppm n-butanol in an exposure chamber and four hours after exposure termination. A total of 19 cytokines and chemokines were quantified. Furthermore, at baseline and during the exposure session, participants rated the perceived intensity, valence and levels of symptoms and autonomic recordings were obtained.The physiological and psychophysical measurements during the n-butanol exposure session verified a specific response in MCS individuals only. However, MCS subjects and healthy controls displayed similar upper airway inflammatory mediator profiles (P>0.05 at baseline. Likewise, direct comparison of mediator levels in the MCS group and controls after n-butanol exposure revealed no significant group differences.We demonstrate no abnormal upper airway inflammatory mediator levels in MCS subjects before or after a symptom-eliciting exposure to low dose n-butanol, implying that upper airways of MCS subjects are functionally intact at the level of cytokine and chemokine production and secretory capacity. This suggests that previous findings of increased cytokine plasma levels in MCS are unlikely to be caused by systemic priming via excessive upper airway inflammatory processes.
Dantoft, Thomas Meinertz; Skovbjerg, Sine; Andersson, Linus; Claeson, Anna-Sara; Lind, Nina; Nordin, Steven; Brix, Susanne
Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by reports of recurrent symptoms in response to low level exposure to various chemical substances. Recent findings suggests that dysregulation of the immune system may play a role in MCS pathophysiology. The aim of this study was to examine baseline and low dose n-butanol-induced upper airway inflammatory response profiles in MCS subjects versus healthy controls. Eighteen participants with MCS and 18 age- and sex-matched healthy controls were enrolled in the study. Epithelial lining fluid was collected from the nasal cavity at three time points: baseline, within 15 minutes after being exposed to 3.7 ppm n-butanol in an exposure chamber and four hours after exposure termination. A total of 19 cytokines and chemokines were quantified. Furthermore, at baseline and during the exposure session, participants rated the perceived intensity, valence and levels of symptoms and autonomic recordings were obtained. The physiological and psychophysical measurements during the n-butanol exposure session verified a specific response in MCS individuals only. However, MCS subjects and healthy controls displayed similar upper airway inflammatory mediator profiles (P>0.05) at baseline. Likewise, direct comparison of mediator levels in the MCS group and controls after n-butanol exposure revealed no significant group differences. We demonstrate no abnormal upper airway inflammatory mediator levels in MCS subjects before or after a symptom-eliciting exposure to low dose n-butanol, implying that upper airways of MCS subjects are functionally intact at the level of cytokine and chemokine production and secretory capacity. This suggests that previous findings of increased cytokine plasma levels in MCS are unlikely to be caused by systemic priming via excessive upper airway inflammatory processes.
Chemical Kinetic Insights into the Octane Number and Octane Sensitivity of Gasoline Surrogate Mixtures
Singh, Eshan
Gasoline octane number is a significant empirical parameter for the optimization and development of internal combustion engines capable of resisting knock. Although extensive databases and blending rules to estimate the octane numbers of mixtures have been developed and the effects of molecular structure on autoignition properties are somewhat understood, a comprehensive theoretical chemistry-based foundation for blending effects of fuels on engine operations is still to be developed. In this study, we present models that correlate the research octane number (RON) and motor octane number (MON) with simulated homogeneous gas-phase ignition delay times of stoichiometric fuel/air mixtures. These correlations attempt to bridge the gap between the fundamental autoignition behavior of the fuel (e.g., its chemistry and how reactivity changes with temperature and pressure) and engine properties such as its knocking behavior in a cooperative fuels research (CFR) engine. The study encompasses a total of 79 hydrocarbon gasoline surrogate mixtures including 11 primary reference fuels (PRF), 43 toluene primary reference fuels (TPRF), and 19 multicomponent (MC) surrogate mixtures. In addition to TPRF mixture components of iso-octane/n-heptane/toluene, MC mixtures, including n-heptane, iso-octane, toluene, 1-hexene, and 1,2,4-trimethylbenzene, were blended and tested to mimic real gasoline sensitivity. ASTM testing protocols D-2699 and D-2700 were used to measure the RON and MON of the MC mixtures in a CFR engine, while the PRF and TPRF mixtures' octane ratings were obtained from the literature. The mixtures cover a RON range of 0–100, with the majority being in the 70–100 range. A parametric simulation study across a temperature range of 650–950 K and pressure range of 15–50 bar was carried out in a constant-volume homogeneous batch reactor to calculate chemical kinetic ignition delay times. Regression tools were utilized to find the conditions at which RON and MON
A non-contact, thermal noise based method for the calibration of lateral deflection sensitivity in atomic force microscopy
Mullin, Nic; Hobbs, Jamie K.
Calibration of lateral forces and displacements has been a long standing problem in lateral force microscopies. Recently, it was shown by Wagner et al. that the thermal noise spectrum of the first torsional mode may be used to calibrate the deflection sensitivity of the detector. This method is quick, non-destructive and may be performed in situ in air or liquid. Here we make a full quantitative comparison of the lateral inverse optical lever sensitivity obtained by the lateral thermal noise method and the shape independent method developed by Anderson et al. We find that the thermal method provides accurate results for a wide variety of rectangular cantilevers, provided that the geometry of the cantilever is suitable for torsional stiffness calibration by the torsional Sader method, in-plane bending of the cantilever may be eliminated or accounted for and that any scaling of the lateral deflection signal between the measurement of the lateral thermal noise and the measurement of the lateral deflection is eliminated or corrected for. We also demonstrate that the thermal method may be used to characterize the linearity of the detector signal as a function of position, and find a deviation of less than 8% for the instrument used
Large-Area Chemical Vapor Deposited MoS2 with Transparent Conducting Oxide Contacts toward Fully Transparent 2D Electronics
Dai, Zhenyu
2D semiconductors are poised to revolutionize the future of electronics and photonics, much like transparent oxide conductors and semiconductors have revolutionized the display industry. Herein, these two types of materials are combined to realize fully transparent 2D electronic devices and circuits. Specifically, a large-area chemical vapor deposition process is developed to grow monolayer MoS2 continuous films, which are, for the first time, combined with transparent conducting oxide (TCO) contacts. Transparent conducting aluminum doped zinc oxide contacts are deposited by atomic layer deposition, with composition tuning to achieve optimal conductivity and band-offsets with MoS2. The optimized process gives fully transparent TCO/MoS2 2D electronics with average visible-range transmittance of 85%. The transistors show high mobility (4.2 cm2 V−1 s−1), fast switching speed (0.114 V dec−1), very low threshold voltage (0.69 V), and large switching ratio (4 × 108). To our knowledge, these are the lowest threshold voltage and subthreshold swing values reported for monolayer chemical vapor deposition MoS2 transistors. The transparent inverters show fast switching properties with a gain of 155 at a supply voltage of 10 V. The results demonstrate that transparent conducting oxides can be used as contact materials for 2D semiconductors, which opens new possibilities in 2D electronic and photonic applications.
Risk assessment of contact allergens: a feasibility study
Iersel AAJ van; LEO; LGM; LPI
Skin sensitization, allergic contact dermatitis, is not a life-threatening condition but it can be very impairing. For that reason contemporary legislation prescribes the assessment of the skin sensitizing properties of substances like chemicals, house-hold and personel-care products. In general,
Multiple chemical sensitivity and workplace discrimination: the national EEOC ADA research project.
Vierstra, Courtney V; Rumrill, Phillip D; Koch, Lynn C; McMahon, Brian T
Information from the Integrated Mission System of the United States Equal Employment Opportunity Commission (EEOC) was used to investigate the employment discrimination experiences of Americans with multiple chemical sensitivity (MCS) in comparison to Americans in a general disability group with allergies, asthma, HIV, gastrointestinal impairment, cumulative trauma disorder and tuberculosis. Specifically, the researchers examined demographic characteristics of the charging parties; the industry designation, location, and size of employers against whom allegations were filed; the nature of discrimination (i.e., type of adverse action) alleged to occur; and the legal outcomes or resolutions of these allegations. Findings indicate that persons with MCS were, on average, older than the comparison group and comparatively overrepresented by Caucasians and women. People with MCS were proportionally more likely than the comparison group to allege discrimination related to reasonable accommodations. People with MCS were proportionally more likely than the comparison group to file allegations against employers in the manufacturing and public administration industries, employers with 201-500 workers, and employers in the Western Census region. People with MCS were proportionally more likely than the comparison group to receive non-merit resolutions as a result of the EEOC's Americans with Disabilities Act Title I investigatory process. Implications for policy and advocacy are addressed.
A highly stable and sensitive chemically modified screen-printed electrode for sulfide analysis
Tsai, D.-M. [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China); Kumar, Annamalai Senthil [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China); Zen, J.-M. [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China)]. E-mail: jmzen@dragon.nchu.edu.tw
We report here a highly stable and sensitive chemically modified screen-printed carbon electrode (CMSPE) for sulfide analysis. The CMSPE was prepared by first ion-exchanging ferricyanide into a Tosflex anion-exchange polymer and then sealing with a tetraethyl orthosilicate sol-gel layer. The sol-gel overlayer coating was crucial to stabilize the electron mediator (i.e., Fe(China){sub 6} {sup 3-}) from leaching. The strong interaction between the oxy-hydroxy functional group of sol-gel and the hydrophilic sites of Tosflex makes the composite highly rigid to trap the ferricyanide mediator. An obvious electrocatalytic sulfide oxidation current signal at {approx}0.20 V versus Ag/AgCl in pH 7 phosphate buffer solution was observed at the CMSPE. A linear calibration plot over a wide range of 0.1 {mu}M to 1 mM with a slope of 5.6 nA/{mu}M was obtained by flow injection analysis. The detection limit (S/N = 3) was 8.9 nM (i.e., 25.6 ppt). Practical utility of the system was applied to the determination of sulfide trapped from cigarette smoke and sulfide content in hot spring water.
Chemical sensitizers for hypoxic cells: a decade of experience in clinical radiotherapy
Dische, S [Mount Vernon Hospital, Northwood (UK)
The clinical work with chemical agents to restore the radiosensitivity of hypoxic cells began in 1973 with metronidazole, misonidazole was first given in 1974. The results so far recorded of the clinical trials with misonidazole have been generally disappointing. Hypoxic cells must exist in all human tumours presenting for treatment and it is, however, probable that the oxygen effect is an important one at all dose fractionation regimes employed in radiotherapy but, after conventional fractionated radiotherapy, hypoxia may be a reason for failure in only a proportion of cases. The most important factor underlying the failure of misonidazole to acheive useful advantage is undoubtedly the low radiosensitizing concentrations achievable with the permitted dose of this neurotoxic drug. New drugs are under development and some have different dose-limiting toxicity. Those showing promise at this time are the Stanford compound, SR-2508 and the Roche compounds, Ro 03-8799. It is possible that the greatest sensitization with the greatest tolerance will be achieved by a combination of drugs.
GaN-based vertical-cavity surface-emitting lasers with tunnel junction contacts grown by metal-organic chemical vapor deposition
Lee, SeungGeun; Forman, Charles A.; Lee, Changmin; Kearns, Jared; Young, Erin C.; Leonard, John T.; Cohen, Daniel A.; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.
We report the first demonstration of III–nitride vertical-cavity surface-emitting lasers (VCSELs) with tunnel junction (TJ) intracavity contacts grown completely by metal–organic chemical vapor deposition (MOCVD). For the TJs, n++-GaN was grown on in-situ activated p++-GaN after buffered HF surface treatment. The electrical properties and epitaxial morphologies of the TJs were first investigated on TJ LED test samples. A VCSEL with a TJ intracavity contact showed a lasing wavelength of 408 nm, a threshold current of ∼15 mA (10 kA/cm2), a threshold voltage of 7.8 V, a maximum output power of 319 µW, and a differential efficiency of 0.28%.
Sensitivity of ab Initio vs Empirical Methods in Computing Structural Effects on NMR Chemical Shifts for the Example of Peptides.
Sumowski, Chris Vanessa; Hanni, Matti; Schweizer, Sabine; Ochsenfeld, Christian
The structural sensitivity of NMR chemical shifts as computed by quantum chemical methods is compared to a variety of empirical approaches for the example of a prototypical peptide, the 38-residue kaliotoxin KTX comprising 573 atoms. Despite the simplicity of empirical chemical shift prediction programs, the agreement with experimental results is rather good, underlining their usefulness. However, we show in our present work that they are highly insensitive to structural changes, which renders their use for validating predicted structures questionable. In contrast, quantum chemical methods show the expected high sensitivity to structural and electronic changes. This appears to be independent of the quantum chemical approach or the inclusion of solvent effects. For the latter, explicit solvent simulations with increasing number of snapshots were performed for two conformers of an eight amino acid sequence. In conclusion, the empirical approaches neither provide the expected magnitude nor the patterns of NMR chemical shifts determined by the clearly more costly ab initio methods upon structural changes. This restricts the use of empirical prediction programs in studies where peptide and protein structures are utilized for the NMR chemical shift evaluation such as in NMR refinement processes, structural model verifications, or calculations of NMR nuclear spin relaxation rates.
Highly sensitive refractive index fiber inline Mach-Zehnder interferometer fabricated by femtosecond laser micromachining and chemical etching
Sun, Xiao-Yan; Chu, Dong-Kai; Dong, Xin-Ran; Zhou, Chu; Li, Hai-Tao; Luo-Zhi; Hu, You-Wang; Zhou, Jian-Ying; Cong-Wang; Duan, Ji-An
A High sensitive refractive index (RI) sensor based on Mach-Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed, which is fabricated by femtosecond laser transversal-scanning inscription method and chemical etching. A rectangular cavity structure is formed in part of fiber core and cladding interface. The MZI sensor shows excellent refractive index sensitivity and linearity, which exhibits an extremely high RI sensitivity of -17197 nm/RIU (refractive index unit) with the linearity of 0.9996 within the refractive index range of 1.3371-1.3407. The experimental results are consistent with theoretical analysis.
Changes on the mineralogical and physico-chemical properties of a compacted bentonite in contact with hyperalkaline pore fluids
Fernandez, A.M.; Melon, A.; Sanchez, D.M.
Document available in extended abstract form only. In high-level radioactive waste disposal (HLW) concepts, compacted bentonites are being considered in many countries as a sealing material because of their low permeability, high swelling capacity and high plasticity. In the case of the geological disposal of nuclear wastes in argillaceous host formations, concrete will be also used as support of tunnels and galleries and as waste containment material. Therefore, the bentonite barrier will become saturated with the water resulting from the host-rock/concrete interaction. An understanding of the rate and nature of the bentonite alteration, as well as the evolution of the bentonite pore water in the long-term is important for performance assessment. In this work the behaviour of the bentonite has been simulated in a laboratory test. A concrete-bentonite interaction experiment has been performed at a high solid to liquid ratio with FEBEX bentonite. The aim of the experiment was to analyse the buffering capacity of the bentonite and the clay mineral stability in a high-pH environment over a long contact period. The rate of pH buffering capacity of the bentonite is related to its surface hydroxyl sites (≡SOH) located along the edges of the clay platelets (fast reaction), and the montmorillonite crystal lattice itself (governed by reaction kinetics). Two infiltration tests with hyper-alkaline water were performed with FEBEX bentonite compacted at a dry density of 1.65 g/cm 3 with a hygroscopic water content (w.c.) of 13.4% in small-scale hermetic cells (50- mm diameter and 25-mm high). The experiments were running for 1.65 years under anoxic conditions inside an anoxic glove (< 1 ppm O 2 ) box and at temperature of 30-35 deg. C. The type of alkaline solution was a Na-K-OH water in equilibrium with portlandite, Ca(OH) 2 , at pH 13.5. This water is representative of an average pore water of a mortar made with CEM-I-SR type Portland cement (sulphate-resistant) at a 0
Contact dermatitis caused by preservatives.
Yim, Elizabeth; Baquerizo Nole, Katherine L; Tosti, Antonella
Preservatives are biocidal chemicals added to food, cosmetics, and industrial products to prevent the growth of microorganisms. They are usually nontoxic and inexpensive and have a long shelf life. Unfortunately, they commonly cause contact dermatitis. This article reviews the most important classes of preservatives physicians are most likely to encounter in their daily practice, specifically isothiazolinones, formaldehyde and formaldehyde-releasers, iodopropynyl butylcarbamate, methyldibromoglutaronitrile, and parabens. For each preservative mentioned, the prevalence of sensitization, clinical presentation of contact dermatitis, patch testing concentrations, cross reactions, and related legislation will be discussed. Mandatory labeling of preservatives is required in some countries, but not required in others. Until policies are made, physicians and patients must be proactive in identifying potential sensitizers and removing their use. We hope that this article will serve as a guide for policy makers in creating legislation and future regulations on the use and concentration of certain preservatives in cosmetics and industrial products.
Acute sensitivity of freshwater mollusks and commonly tested invertebrates to select chemicals with different toxic models of action
Previous studies indicate that freshwater mollusks are more sensitive than commonly tested organisms to some chemicals, such as copper and ammonia. Nevertheless, mollusks are generally under-represented in toxicity databases. Studies are needed to generate data with which to comp...
Deranged Dimensionality of Vestibular Re-Weighting in Multiple Chemical Sensitivity
Alessandro Micarelli
Full Text Available Background: Multiple chemical sensitivity (MCS is a chronic multisystem condition characterized by low levels of multiple chemical susceptibility inducing a spectrum of central nervous system symptoms, including dizziness. Thus, considering (i the overlapping psychogenic and organic burdens shared in MCS development and in vestibular disorders; (ii the number of previous studies describing central processing impairment related to inner ear inflow in this syndrome; and (iii the lack of literature with respect to clinical evidence of the presentation of MCS dizziness, the purpose of the present study was to highlight the possible hidden aspects of vestibular impairment by applying the recent contribution of implemented otoneurological testing, inferential statistic and principal component (PC analysis in 18 MCS and 20 healthy subjects (HC; Methods: Both groups filled in a dizziness and environment exposure inventory and underwent the Rod and Disc and Rod and Frame Test, video Head Impulse Test (vHIT and Static Posturography Test (SPT with fast Fourier Transform (FFT. Between-group analysis of variance and PC analysis implemented on otoneurological variables were performed; Results: Defective vestibular processing was identified in 18 MCS patients (11 female and 7 male; mean age 49.5 ± 9.3 years by finding a significant increase in SPT and FFT parameters and in Visual Dependency (VD behaviour and a decrease in vHIT scores. Component correlation analysis in MCS showed a positive correlation of FFT parameters in PC1 and SPT parameters in PC2 with a negative correlation of vHIT and VD values in PC2. HC subjects demonstrated a positive correlation of VD and SPT parameters in PC1 and FFT parameters in PC2. Conclusion: Inferential and PC analysis provided the opportunity to disclose such possible hidden phenomena to (i support that MCS physiopathological cascades could lead to a vestibular decay; and (ii suggest rearrangement of the dimension of the
Lack of contralateral suppression in transient-evoked otoacoustic emissions in multiple chemical sensitivity: a clinical correlation study
Full Text Available Multiple chemical sensitivity (MCS is a chronic disorder characterized by a variety of symptoms associated with the exposure to chemicals at a concentration below the toxic level. Previous studies have demonstrated peculiar responses in brain activity in these patients with respect to sensory stimuli while the association between chemical sensitivity and other environmental intolerances such as noise sensitivity has been questioned by researchers. In this study, a cohort of 18 MCS patients underwent transient-evoked otoacoustic emission (TEOAE testing with and without contralateral suppression to evaluate the functionality of the medial olivocochlear (MOC reflex involved in speech-in-noise sensitivity. Results were compared with an age- and gender-matched control group (n = 20 and correlation analysis with disease onset and quick environmental exposure sensitivity inventory (qEESI symptom severity scale was performed. Subjects affected by MCS showed statistically significant impairment of MOC reflex, and the onset of the disease and several symptom subscales showed to be correlated to such reduction in some of the frequencies tested. These data suggest that alterations of MOC reflex could be part of the complex features of this disease although more studies are needed to further explore auditory perception disorders in environmental intolerances.
Further development of LLNA:DAE method as stand-alone skin-sensitization testing method and applied for evaluation of relative skin-sensitizing potency between chemicals.
Yamashita, Kunihiko; Shinoda, Shinsuke; Hagiwara, Saori; Itagaki, Hiroshi
To date, there has been no well-established local lymph node assay (LLNA) that includes an elicitation phase. Therefore, we developed a modified local lymph node assay with an elicitation phase (LLNA:DAE) to discriminate true skin sensitizers from chemicals that gave borderline positive results and previously reported this assay. To develop the LLNA:DAE method as a useful stand-alone testing method, we investigated the complete procedure for the LLNA:DAE method using hexyl cinnamic aldehyde (HCA), isoeugenol, and 2,4-dinitrochlorobenzene (DNCB) as test compounds. We defined the LLNA:DAE procedure as follows: in the dose-finding test, four concentrations of chemical applied to dorsum of the right ear on days 1, 2, and 3 and dorsum of both ears on day 10. Ear thickness and skin irritation score were measured on days 1, 3, 5, 10, and 12. Local lymph nodes were excised and weighed on day 12. The test dose for the primary LLNA:DAE study was selected as the dose that gave the highest left ear lymph node weight in the dose-finding study, or the lowest dose that produced a left ear lymph node of over 4 mg. This procedure was validated using nine different chemicals. Furthermore, qualitative relationship was observed between the degree of elicitation response in the left ear lymph node and the skin sensitizing potency of 32 chemicals tested in this study and the previous study. These results indicated that LLNA:DAE method was as first LLNA method that was able to evaluate the skin sensitizing potential and potency in elicitation response.
Advantages of chemical exchange-sensitive spin-lock (CESL) over chemical exchange saturation transfer (CEST) for hydroxyl- and amine-water proton exchange studies.
Jin, Tao; Kim, Seong-Gi
The chemical exchange (CE) rate of endogenous hydroxyl and amine protons with water is often comparable to the difference in their chemical shifts. These intermediate exchange processes have been imaged by the CE saturation transfer (CEST) approach with low-power and long-duration irradiation. However, the sensitivity is not optimal and, more importantly, the signal is contaminated by slow magnetization transfer processes. Here, the properties of CEST signals are compared with those of a CE-sensitive spin-lock (CESL) technique irradiating at the labile proton frequency. First, using a higher power and shorter irradiation in CE-MRI, we obtain: (i) an increased selectivity to faster CE rates via a higher sensitivity to faster CEs and a lower sensitivity to slower CEs and magnetization transfer processes; and (ii) a decreased in vivo asymmetric magnetization transfer contrast measured at ±15 ppm. The sensitivity gain of CESL over CEST is higher for a higher power and shorter irradiation. Unlike CESL, CEST signals oscillate at a very high power and short irradiation. Second, time-dependent CEST and CESL signals are well modeled by analytical solutions of CE-MRI with an asymmetric population approximation, which can be used for quantitative CE-MRI and validated by simulations of Bloch-McConnell equations and phantom experiments. Finally, the in vivo amine-water proton exchange contrast measured at 2.5 ppm with ω1 = 500 Hz is 18% higher in sensitivity for CESL than CEST at 9.4 T. Overall, CESL provides better exchange rate selectivity and sensitivity than CEST; therefore, CESL is more suitable for CE-MRI of intermediate exchange protons. Copyright © 2014 John Wiley & Sons, Ltd.
Allergic contact dermatitis caused by a new temporary blue-black tattoo dye - sensitization to genipin from jagua (Genipa americana L.) fruit extract.
Bircher, Andreas J; Sigg, Rita; Scherer Hofmeier, Kathrin; Schlegel, Urs; Hauri, Urs
Temporary tattoos made with an extract of the jagua fruit (Genipa americana L.) are becoming increasingly popular. It is claimed that it is 'dermatologically tested' and does not contain p-phenylenediamine. Extracts of jagua and gardenia fruits have been used by indigenous people in South America, as well as in traditional Chinese medicine, for centuries. Genipin is currently used for its cross-linking effect in the manufacture of polysaccharides, and is being investigated for its anti-inflammatory and other properties. To report the presence of the allergenic substance genipin in a self-administered temporary tattoo dye made from the fruit juice of jagua (Genipa americana L.). A 39-year-old female who repeatedly applied 'completely natural and 100% safe' Earth Jagua® tattoo, obtained via the internet, to her left hand developed allergic contact dermatitis within 6 weeks. Analysis of the dye showed the presence of geniposide and genipin. Patch tests with the dye and with its main components, including genipin, gave strong positive reactions to the latter. There was no sensitization to other ingredients or p-amino compounds. We report an extensively evaluated case of allergic contact dermatitis caused by a temporary Earth Jagua® tattoo. The allergen identified is genipin, a substance that is increasingly used for tattoos and as a therapeutic agent in medicine. This could result in an increase in the number of allergic reactions in the future. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity.
Alessandrini, Marco; Micarelli, Alessandro; Chiaravalloti, Agostino; Bruno, Ernesto; Danieli, Roberta; Pierantozzi, Mariangela; Genovesi, Giuseppe; Öberg, Johanna; Pagani, Marco; Schillaci, Orazio
Multiple chemical sensitivity (MCS) patients usually react to odour compounds and the majority of neuroimaging studies assessed, especially at the cortical level, many olfactory-related correlates. The purpose of the present study was to depict sub-cortical metabolic changes during a neutral (NC) and pure (OC) olfactory stimulation by using a recently validated (18)F-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computer tomography procedure in 26 MCS and 11 healthy (HC) resting subjects undergoing a battery of clinical tests. Twelve subcortical volumes of interest were identified by the automated anatomical labeling library and normalized to thalamus FDG uptake. In both groups, when comparing OC to NC, the within-subjects ANOVA demonstrated a relative decreased metabolism in bilateral putamen and hippocampus and a relative increased metabolism in bilateral amygdala, olfactory cortex (OLF), caudate and pallidum. The between-groups ANOVA demonstrated in MCS a significant higher metabolism in bilateral OLF during NC. As in HC subjects negative correlations were found in OC between FDG uptake in bilateral amygdala and hippocampus and odor pleasantness scale, the latter positively correlated with MCS subjects' bilateral putamen FDG uptake in OC. Besides FDG uptake resemblances in both groups were found, for the first time a relative higher metabolism increase in OLF in MCS subjects at rest with respect to HC was found. When merging this aspect to the different subcortical FDG uptake correlations patterns in the two groups, the present study demonstrated to describe a peculiar metabolic index of behavioral and neurological aspects of MCS complaints.
Vertically aligned carbon nanotube field emitter arrays with Ohmic base contact to silicon by Fe-catalyzed chemical vapor deposition
Morassutto, M.; Tiggelaar, Roald M.; Smithers, M.A.; Smithers, M.A.; Gardeniers, Johannes G.E.
Abstract In this study, dense arrays of aligned carbon nanotubes are obtained by thermal catalytic chemical vapor deposition, using Fe catalyst dispersed on a thin Ta layer. Alignment of the carbon nanotubes depends on the original Fe layer thickness from which the catalyst dispersion is obtained by
Effects of chemical intermixing on electrical and thermal contact conductances at metallized bismuth and antimony telluride interfaces
Devender,; Mehta, Rutvik J.; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Yamaguchi, Masashi [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)
Tailoring electrical and thermal contact conductivities (Σ{sub c} and Γ{sub c}) across metallized pnictogen chalcogenide interfaces is key for realizing efficient thermoelectric devices. The authors report that Cu, Ni, Ti, and Ta diffusion and interfacial telluride formation with n-Bi{sub 2}Te{sub 3} and p-Sb{sub 2}Te{sub 3} influence both Σ{sub c} and Γ{sub c}. Cu metallization yields the highest Γ{sub c} and the lowest Σ{sub c}, correlating with maximal metal diffusion and copper telluride formation. Ni diffuses less and yields the highest Σ{sub c} with Sb{sub 2}Te{sub 3} due to p-type nickel telluride formation, which diminishes Σ{sub c} improvement with n-Bi{sub 2}Te{sub 3} interfaces. Ta and Ti contacts yield the lowest properties similar to that in Ni-metallized structures. These correlations between interfacial diffusion and phase formation on electronic and thermal transport properties will be important for devising suitable metallization for thermoelectric devices.
Safety evaluation of food contact paper and board using chemical tests and in vitro bioassays: role of known and unknown substances.
Honkalampi-Hämäläinen, U; Bradley, E L; Castle, L; Severin, I; Dahbi, L; Dahlman, O; Lhuguenot, J-C; Andersson, M A; Hakulinen, P; Hoornstra, D; Mäki-Paakkanen, J; Salkinoja-Salonen, M; Turco, L; Stammati, A; Zucco, F; Weber, A; von Wright, A
In vitro toxicological tests have been proposed as an approach to complement the chemical safety assessment of food contact materials, particularly those with a complex or unknown chemical composition such as paper and board. Among the concerns raised regarding the applicability of in vitro tests are the effects of interference of the extractables on the outcome of the cytotoxicity and genotoxicity tests applied and the role of known compounds present in chemically complex materials, such as paper and board, either as constituents or contaminants. To answer these questions, a series of experiments were performed to assess the role of natural substances (wood extracts, resin acids), some additives (diisopropylnaphthalene, phthalates, acrylamide, fluorescent whitening agents) and contaminants (2,4-diaminotoluene, benzo[a]pyrene) in the toxicological profile of paper and board. These substances were individually tested or used to spike actual paper and board extracts. The toxic concentrations of diisopropylnaphthalenes and phthalates were compared with those actually detected in paper and board extracts showing conspicuous toxicity. According to the results of the spiking experiments, the extracts did not affect the toxicity of tested chemicals nor was there any significant metabolic interference in the cases where two compounds were used in tests involving xenobiotic metabolism by the target cells. While the identified substances apparently have a role in the cytotoxicity of some of the project samples, their presence does not explain the total toxicological profile of the extracts. In conclusion, in vitro toxicological testing can have a role in the safety assessment of chemically complex materials in detecting potentially harmful activities not predictable by chemical analysis alone.
Experimental study on the influence of chemical sensitizer on pressure resistance in deep water of emulsion explosives
Liu, Lei; zhang, Zhihua; Wang, Ya; Qin, hao
The study on the pressure resistance performance of emulsion explosives in deep water can provide theoretical basis for underwater blasting, deep-hole blasting and emulsion explosives development. The sensitizer is an important component of emulsion explosives. By using reusable experimental devices to simulate the charge environment in deep water, the influence of the content of chemical sensitizer on the deep-water pressure resistance performance of emulsion explosives was studied. The experimental results show that with the increasing of the content of chemical sensitizer, the deep-water pressure resistance performance of emulsion explosives gradually improves, and when the pressure is fairly large, the effect is particularly pronounced; in a certain range, with the increase of the content of chemical sensitizer, that emulsion explosives' explosion performance also gradually improve, but when the content reaches a certain value, the explosion properties declined instead; under the same emulsion matrix condition, when the content of NANO2 is 0.2%, that the emulsion explosives has good resistance to water pressure and good explosion properties. The correctness of the results above was testified in model blasting.
Sensitivity of chemical vapor deposition diamonds to DD and DT neutrons at OMEGA and the National Ignition Facility
Kabadi, N. V.; Sio, H.; Glebov, V.; Gatu Johnson, M.; MacPhee, A.; Frenje, J. A.; Li, C. K.; Seguin, F.; Petrasso, R.; Forrest, C.; Knauer, J.; Rinderknecht, H. G.
The particle-time-of-flight (pTOF) detector at the National Ignition Facility (NIF) is used routinely to measure nuclear bang-times in inertial confinement fusion implosions. The active detector medium in pTOF is a chemical vapor deposition diamond. Calibration of the detectors sensitivity to neutrons and protons would allow measurement of nuclear bang times and hot spot areal density (�R) on a single diagnostic. This study utilizes data collected at both NIF and Omega in an attempt to determine pTOF's absolute sensitivity to neutrons. At Omega pTOF's sensitivity to DT-n is found to be stable to within 8% at different bias voltages. At the NIF pTOF's sensitivity to DD-n varies by up to 59%. This variability must be decreased substantially for pTOF to function as a neutron yield detector at the NIF. Some possible causes of this variability are ruled out.
Expression of CD73 slows down migration of skin dendritic cells, affecting the sensitization phase of contact hypersensitivity reactions in mice.
Neuberger, A; Ring, S; Silva-Vilches, C; Schrader, J; Enk, A; Mahnke, K
Application of haptens to the skin induces release of immune stimulatory ATP into the extracellular space. This "danger" signal can be converted to immunosuppressive adenosine (ADO) by the action of the ectonucleotidases CD39 and CD73, expressed by skin and immune cells. Thus, the expression and regulation of CD73 by skin derived cells may have crucial influence on the outcome of contact hypersensitivity (CHS) reactions. To investigate the role of CD73 expression during 2,4,6-trinitrochlorobenzene (TNCB) induced CHS reactions. Wild type (wt) and CD73 deficient mice were subjected to TNCB induced CHS. In the different mouse strains the resulting ear swelling reaction was recorded along with a detailed phenotypic analysis of the skin migrating subsets of dendritic cells (DC). In CD73 deficient animals the motility of DC was higher as compared to wt animals and in particular after sensitization we found increased migration of Langerin + DC from skin to draining lymph nodes (LN). In the TNCB model this led to a stronger sensitization as indicated by increased frequency of interferon-γ producing T cells in the LN and an increased ear thickness after challenge. CD73 derived ADO production slows down migration of Langerin + DC from skin to LN. This may be a crucial mechanism to avoid over boarding immune reactions against haptens. Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.
Colors and contact dermatitis.
Bonamonte, Domenico; Foti, Caterina; Romita, Paolo; Vestita, Michelangelo; Angelini, Gianni
The diagnosis of skin diseases relies on several clinical signs, among which color is of paramount importance. In this review, we consider certain clinical presentations of both eczematous and noneczematous contact dermatitis in which color plays a peculiar role orientating toward the right diagnosis. The conditions that will be discussed include specific clinical-morphologic subtypes of eczematous contact dermatitis, primary melanocytic, and nonmelanocytic contact hyperchromia, black dermographism, contact chemical leukoderma, and others. Based on the physical, chemical, and biologic factors underlying a healthy skin color, the various skin shades drawing a disease picture are thoroughly debated, stressing their etiopathogenic origins and histopathologic aspects.
Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment.
Avonto, Cristina; Wang, Mei; Chittiboyina, Amar G; Vukmanovic, Stanislav; Khan, Ikhlas A
Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.
Evaluation of a high-throughput peptide reactivity format assay for assessment of the skin sensitization potential of chemicals
Chin Lin eWong
Full Text Available The direct peptide reactivity assay (DPRA is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the research is to ensure that the analytical component of the peptide reactivity assay is robust, accurate and reproducible in accordance with criteria that are used for the validation of bioanalytical methods. Analytical performance was evaluated using quality control samples (QCs; heptapeptides at low, medium and high concentrations and incubation of control chemicals (chemicals with known sensitization capacity, weak, moderate, strong, extreme and non-sensitizers with each of three synthetic heptapeptides, viz Cor1-C420 (Ac-NKKCDLF, cysteine- (Ac-RFAACAA and lysine- (Ac-RFAAKAA containing heptapeptides. The optimal incubation temperature for all three heptapeptides was 25°C. Apparent heptapeptide depletion was affected by vial material composition. Incubation of test chemicals with Cor1-C420, showed that peptide depletion was unchanged in polypropylene vials over 3-days storage in an autosampler but this was not the case for borosilicate glass vials. For cysteine-containing heptapeptide, the concentration was not stable by day 3 post-incubation in borosilicate glass vials. Although the lysine-containing heptapeptide concentration was unchanged in both polypropylene and borosilicate glass vials, the apparent extent of lysine-containing heptapeptide depletion by ethyl acrylate, differed between polypropylene (24.7% and glass (47.3% vials. Additionally, the peptide-chemical complexes for Cor1-C420-cinnamaldehyde and cysteine-containing heptapeptide-2,4-dinitrochlorobenzene were partially reversible during 3-days of autosampler storage. These observations further
Laser photoacoustic spectroscopy helps fight terrorism: High sensitivity detection of chemical Warfare Agent and explosives
Patel, C. K. N.
Tunable laser photoacoustic spectroscopy is maturing rapidly in its applications to real world problems. One of the burning problems of the current turbulent times is the threat of terrorist acts against civilian population. This threat appears in two distinct forms. The first is the potential release of chemical warfare agents (CWA), such as the nerve agents, in a crowded environment. An example of this is the release of Sarin by Aum Shinrikyo sect in a crowded Tokyo subway in 1995. An example of the second terrorist threat is the ever-present possible suicide bomber in crowded environment such as airports, markets and large buildings. Minimizing the impact of both of these threats requires early detection of the presence of the CWAs and explosives. Photoacoustic spectroscopy is an exquisitely sensitive technique for the detection of trace gaseous species, a property that Pranalytica has extensively exploited in its CO2 laser based commercial instrumentation for the sub-ppb level detection of a number of industrially important gases including ammonia, ethylene, acrolein, sulfur hexafluoride, phosphine, arsine, boron trichloride and boron trifluoride. In this presentation, I will focus, however, on our recent use of broadly tunable single frequency high power room temperature quantum cascade lasers (QCL) for the detection of the CWAs and explosives. Using external grating cavity geometry, we have developed room temperature QCLs that produce continuously tunable single frequency CW power output in excess of 300 mW at wavelengths covering 5 μm to 12 μm. I will present data that show a CWA detection capability at ppb levels with false alarm rates below 1:108. I will also show the capability of detecting a variety of explosives at a ppb level, again with very low false alarm rates. Among the explosives, we have demonstrated the capability of detecting homemade explosives such as triacetone triperoxide and its liquid precursor, acetone which is a common household
Patients with multiple contact allergies
Carlsen, Berit Christina; Andersen, Klaus Ejner; Menné, Torkil
Patients with multiple contact allergies, also referred to as polysensitized, are more frequent than predicted from prevalence of single sensitivities. The understanding of why some people develop multiple contact allergies, and characterization of patients with multiple contact allergies...... of developing multiple contact allergies. Evidence of allergen clusters among polysensitized individuals is also reviewed. The literature supports the idea that patients with multiple contact allergies constitute a special entity within the field of contact allergy. There is no generally accepted definition...... of patients with multiple contact allergies. We suggest that contact allergy to 3 or more allergens are defined as multiple contact allergies....
Generation of dissolved organic matter and byproducts from activated sludge during contact with sodium hypochlorite and its implications to on-line chemical cleaning in MBR.
Cai, Weiwei; Liu, Jiaqi; Zhang, Xiangru; Ng, Wun Jern; Liu, Yu
On-line chemical cleaning of membranes with sodium hypochlorite (NaClO) has been commonly employed for maintaining a constant permeability of membrane bioreactor (MBR) due to its simple and efficient operation. However, activated sludge is inevitably exposed to NaClO during this cleaning process. In spite of the broad applications of on-line chemical cleaning in MBR such as chemical cleaning-in-place (CIP) and chemical enhanced backwash (CEB), little information is currently available for the release of emerging dissolved organic matter (DOM) and byproducts from this prevalent practice. Therefore, in this study, activated sludge suspended in a phosphate buffered saline solution was exposed to different doses of NaClO in order to determine the generation of potential DOM and byproducts. The results showed the occurrence of significant DOM release (up to 24.7 mg/L as dissolved organic carbon) after exposure to NaClO for 30 min. The dominant components of the released DOM were characterized to be humic acid-like as well as protein-like substances by using an excitation-emission matrix fluorescence spectrophotometer. Furthermore, after the contact of activated sludge with NaClO, 19 kinds of chlorinated and brominated byproducts were identified by ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, eight of which were confirmed and characterized with standard compounds. Many byproducts were found to be halogenated aromatic compounds, including halopyrroles and halo(hydro)benzoquinones, which had been reported to be significantly more toxic than the halogenated aliphatic ones. Consequently, this study offers new insights into the practice of on-line chemical cleaning, and opens up a window to re-examine the current operation of MBR by looking into the generation of micropollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.
Clinical vocabulary as a boundary object in multidisciplinary care management of multiple chemical sensitivity, a complex and chronic condition.
Sampalli, Tara; Shepherd, Michael; Duffy, Jack
Research has shown that accurate and timely communication between multidisciplinary clinicians involved in the care of complex and chronic health conditions is often challenging. The domain knowledge for these conditions is heterogeneous, with poorly categorized, unstructured, and inconsistent clinical vocabulary. The potential of boundary object as a technique to bridge communication gaps is explored in this study. A standardized and controlled clinical vocabulary was developed as a boundary object in the domain of a complex and chronic health condition, namely, multiple chemical sensitivity, to improve communication among multidisciplinary clinicians. A convenience sample of 100 patients with a diagnosis of multiple chemical sensitivity, nine multidisciplinary clinicians involved in the care of patients with multiple chemical sensitivity, and 36 clinicians in the community participated in the study. Eighty-two percent of the multidisciplinary and inconsistent vocabulary was standardized using the Systematized Nomenclature of Medicine - Clinical Terms (SNOMED(®) CT as a reference terminology. Over 80% of the multidisciplinary clinicians agreed on the overall usefulness of having a controlled vocabulary as a boundary object. Over 65% of clinicians in the community agreed on the overall usefulness of the vocabulary. The results from this study are promising and will be further evaluated in the domain of another complex chronic condition, ie, chronic pain. The study was conducted as a preliminary analysis for developing a boundary object in a heterogeneous domain of knowledge.
Application of BALB/c mouse in the local lymph node assay:BrdU-ELISA for the prediction of the skin sensitizing potential of chemicals.
Hou, Fenxia; Xing, Caihong; Li, Bin; Cheng, Juan; Chen, Wei; Zhang, Man
Allergic contact dermatitis (ACD) is a skin disease characterized by eczema and itching. A considerable proportion of chemicals induce ACD in humans. More than 10,000 substances should be tested for skin sensitization potential under the Registration, Evaluation, Authorization and Restriction of Chemical substances (REACH) regulation. The Local Lymph Node Assay (LLNA) has been designated as the first-choice in vivo assay for sensitization testing by REACH. The LLNA:BrdU-ELISA is a validated non-radioactive modification to the LLNA. For both the LLNA and the LLNA:BrdU-ELISA, CBA/JN mouse is the preferred mouse strain recommended in the regulatory guidelines. However, the availability of CBA/JN mouse in China is only limited to a few animal suppliers, which makes the mouse difficult to obtain. BALB/c mouse, which is widely commercially available, is considered for alternative use but it can only be used in the assay after it has been evaluated by formal validation study. Thus, a validation study was conducted in our laboratory to determine if BALB/c mouse could also be used in the LLNA:BrdU-ELISA. Forty-three test substances including 32 LLNA sensitizers and 11 LLNA non-sensitizers, their vehicles and each concentration used were the same as that used in the formal validation study for the LLNA:BrdU-ELISA using CBA/JN mouse. Female BALB/c mice of 8-10 weeks old were randomly allocated to groups (four mice per group). The test substance (25 μl) or the vehicle alone was applied to the dorsum of both ears daily for 3 consecutive days. A single intraperitoneal injection of 0.5 ml of BrdU (10mg/ml) solution was given on day 5. On day 6, a pair of auricular lymph nodes from each mouse was excised, weighed and stored at -20°C until BrdU-ELISA was conducted. This validation study for the LLNA:BrdU-ELISA using BALB/c mouse correctly identified 30 of 31 sensitizers and 8 of 11 non-sensitizers. The accuracy, sensitivity, specificity, false positive rate, false negative rate
Sensitivity of chemically and electrochemically etched CR 39 polymers to the neutrons of AmBe source
Turek, K.; Spurny, F.; Dajko, G.; Somogyi, G.
Seven samples of polymers by different manufacturers were used in a study of the sensitivity of CR 39 polymers to Am-Be neutrons. In the polymer, proton tracks for a relatively broad energy range can also be recorded. The following characteristics were studied: the sample background for different etching methods, the dependence of sensitivity on the etched thickness and on neutron fluence, the effect of type and thickness of external proton emitters, and the effect of the choice of electric parameters on the resulting sensitivity in electrochemical etching. Good results were obtained when chemical and electrochemical etching was used in combination. It was found that with electrochemical etching, sensitivity decreases for neutron fluence exceeding 10 8 cm -2 . The sensitivity of the studied CR 39 polymer samples only little differed. When the most sensitive polymer was used, the minimum dose equivalent in the human body for Am-Be neutrons which could be determined using combination etching was 0.4 mSv (ie., 40 mrems). (B.S.)
Effect of Hydroxyl Concentration on Chemical Sensitivity of Polyvinyl Alcohol/Carbon-Black Composite Chemiresistors
Hughes, Robert C.; Patel, Sanjay V.; Yelton, W. Graham
The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage (''-OH'') of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an array to distinguish the responses to methanol-water mixtures
Sensitivity of neuroprogenitor cells to chemical-induced apoptosis using a multiplexed assay suitable for high-throughput screening
Druwe, Ingrid; Freudenrich, Theresa M.; Wallace, Kathleen; Shafer, Timothy J.; Mundy, William R.
High-throughput methods are useful for rapidly screening large numbers of chemicals for biological activity, including the perturbation of pathways that may lead to adverse cellular effects. In vitro assays for the key events of neurodevelopment, including apoptosis, may be used in a battery of tests for detecting chemicals that could result in developmental neurotoxicity. Apoptosis contributes to nervous system development by regulating the size of the neuroprogenitor cell pool, and the balance between cellular proliferation and apoptosis during neuroprogenitor cell proliferation helps to determine the size and shape of the nervous system. Therefore, chemicals that affect apoptosis during neuronal development can have deleterious effects on the developing brain. The present study examined the utility of a high-throughput assay to detect chemical-induced apoptosis in mouse or human neuroprogenitor cells, as well as differentiated human neurons derived from induced pluripotent stem cells. Apoptosis was assessed using an assay that measures enzymatic activity of caspase-3/7 in a rapid and cost efficient manner. The results show that all three commercially available models generated a robust source of proliferating neuroprogenitor cells, and that the assay was sensitive and reproducible when used in a multi-well plate format. There were differences in the response of rodent and human neuroprogenitor cells to a set of chemicals previously shown to induce apoptosis in vitro. Neuroprogenitor cells were more sensitive to chemical-induced apoptosis than differentiated neurons, suggesting that neuroprogenitor cells are one of the cell models that should be considered for use in a developmental neurotoxicity screening battery
Ultra-high sensitive hydrazine chemical sensor based on low-temperature grown ZnO nanoparticles
Mehta, S.K.; Singh, Kulvinder; Umar, Ahmad; Chaudhary, G.R.; Singh, Sukhjinder
Graphical abstract: Systematic representation of the fabricated amperometric hydrazine chemical sensor based on ZnO NPs/Au modified electrode. Highlights: ► Synthesis of well-crystalline ZnO NPs has been achieved in aqueous solution. ► ZnO NPs act as efficient electron mediators for hydrazine sensor. ► Extremely high sensitivity and low-detection limit have been obtained. - Abstract: Using well-crystalline ZnO nanoparticles (NPs), an ultra high sensitive hydrazine amperometric sensor has been fabricated and reported in this paper. The ZnO NPs have been synthesized by very simple aqueous solution process at 90 °C and characterized in detail in terms of their morphological, compositional, structural and optical properties. The detailed investigations reveal that the synthesized products are well-crystalline NPs, possessing wurtzite hexagonal phase and exhibit good optical properties. The fabricated amperometric hydrazine sensor exhibits ultra-high sensitivity of ∼97.133 μA cm −2 μM −1 and very low-detection limit of 147.54 nM. To the best of our knowledge, this is the first report in which an ultra-high sensitivity and low-detection limit have been obtained for the hydrazine chemical sensor based on ZnO nanostructures.
Language Contact.
Nelde, Peter Hans
Examines the phenomenon of language contact and recent trends in linguistic contact research, which focuses on language use, language users, and language spheres. Also discusses the role of linguistic and cultural conflicts in language contact situations. (13 references) (MDM)
Chemical allergy in humans
Kimber, Ian; Basketter, David A; Thyssen, Jacob P
Abstract There is considerable interest in the immunobiological processes through which the development of allergic sensitization to chemicals is initiated and orchestrated. One of the most intriguing issues is the basis for the elicitation by chemical sensitizers of different forms of allergic...... reaction; that is, allergic contact dermatitis or sensitization of the respiratory tract associated with occupational asthma. Studies in rodents have revealed that differential forms of allergic sensitization to chemicals are, in large part at least, a function of the selective development of discrete...... functional sub-populations of CD4(+) and CD8(+) T-lymphocytes. Evidence for a similar association of chemical allergy in humans with discrete T-lymphocyte populations is, however, limited. It is of some interest, therefore, that two recent articles from different teams of investigators have shed new light...
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 303 (FGE.303): Spilanthol from chemical group 30
Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister
The Scientific Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (the Panel) was asked to provide scientific advice to the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs in the Member States. In particular...... of the flavouring substances in Europe. However, when the Panel examined the information provided by the European Flavouring Industry on the use levels in various foods, it appeared obvious that the MSDI approach in a number of cases would grossly underestimate the intake by regular consumers of products flavoured...... whether the conclusion for the candidate substance can be applied to the material of commerce, it is necessary to consider the available specifications. Adequate specifications including complete purity criteria and identity for the material of commerce have been provided for the flavouring substance...
Predicting chemically-induced skin reactions. Part I: QSAR models of skin sensitization and their application to identify potentially hazardous compounds
Alves, Vinicius M. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Muratov, Eugene [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Laboratory of Theoretical Chemistry, A.V. Bogatsky Physical-Chemical Institute NAS of Ukraine, Odessa 65080 (Ukraine); Fourches, Denis [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Strickland, Judy; Kleinstreuer, Nicole [ILS/Contractor Supporting the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), P.O. Box 13501, Research Triangle Park, NC 27709 (United States); Andrade, Carolina H. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Tropsha, Alexander, E-mail: alex_tropsha@unc.edu [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States)
Repetitive exposure to a chemical agent can induce an immune reaction in inherently susceptible individuals that leads to skin sensitization. Although many chemicals have been reported as skin sensitizers, there have been very few rigorously validated QSAR models with defined applicability domains (AD) that were developed using a large group of chemically diverse compounds. In this study, we have aimed to compile, curate, and integrate the largest publicly available dataset related to chemically-induced skin sensitization, use this data to generate rigorously validated and QSAR models for skin sensitization, and employ these models as a virtual screening tool for identifying putative sensitizers among environmental chemicals. We followed best practices for model building and validation implemented with our predictive QSAR workflow using Random Forest modeling technique in combination with SiRMS and Dragon descriptors. The Correct Classification Rate (CCR) for QSAR models discriminating sensitizers from non-sensitizers was 71–88% when evaluated on several external validation sets, within a broad AD, with positive (for sensitizers) and negative (for non-sensitizers) predicted rates of 85% and 79% respectively. When compared to the skin sensitization module included in the OECD QSAR Toolbox as well as to the skin sensitization model in publicly available VEGA software, our models showed a significantly higher prediction accuracy for the same sets of external compounds as evaluated by Positive Predicted Rate, Negative Predicted Rate, and CCR. These models were applied to identify putative chemical hazards in the Scorecard database of possible skin or sense organ toxicants as primary candidates for experimental validation. - Highlights: • It was compiled the largest publicly-available skin sensitization dataset. • Predictive QSAR models were developed for skin sensitization. • Developed models have higher prediction accuracy than OECD QSAR Toolbox. • Putative
Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Andrade, Carolina H.; Tropsha, Alexander
Sensitivity of a Chemical Mass Balance model for PM2.5 to source profiles for differing styles of cooking
Abdullahi, K. L.; Delgado-Saborit, J. M.; Harrison, Roy M.
Use of a Chemical Mass Balance model is one of the two most commonly used approaches to estimating atmospheric concentrations of cooking aerosol. Such models require the input of chemical profiles for each of the main sources contributing to particulate matter mass and there is appreciable evidence from the literature that not only the mass emission but also the chemical composition of particulate matter varies according to the food being prepared and the style of cooking. In this study, aerosol has been sampled in the laboratory from four different styles of cooking, i.e. Indian, Chinese, Western and African cooking. The chemical profiles of molecular markers have been quantified and are used individually within a Chemical Mass Balance model applied to air samples collected in a multi-ethnic area of Birmingham, UK. The model results give a source contribution estimate for cooking aerosol which is consistent with other comparable UK studies, but also shows a very low sensitivity of the model to the cooking aerosol profile utilised. A survey of local restaurants suggested a wide range of cooking styles taking place which may explain why no one profile gives an appreciably better fit in the CMB model.
PURPOSE OF REVIEW: The aim of this article is to review recent findings in contact allergy, regarding clinical research. RECENT FINDINGS: The biocide methyldibromo glutaronitrile was identified to be an important sensitizer. Subsequently, it was banned from leave-on cosmetics in the European Union....... Another group of important allergens that have been studied extensively included the fragrances oak moss absolute, isoeugenol, hydroxyisohexyl 3-cyclohexene carboxaldehyde and farnesol. A new fragrance mix II has been developed for standard testing, which includes the two latter compounds. Dose response...... a classification of newly introduced chemicals; increasingly, the local lymph node assay is supplementing and potentially replacing the guinea pig maximization test. Recent advances in occupational contact allergy include, for example, some attempts to improve diagnostics for epoxy resin and other plastic, glue...
Allergic Contact Dermatitis
Meltem Önder
Full Text Available Allergic contact dermatitis is the delayed type hypersensitivity reaction to exogenous agents. Allergic contact dermatitis may clinically present acutely after allergen exposure and initial sensitization in a previously sensitized individual. Acute phase is characterized by erythematous, scaly plaques. In severe cases vesiculation and bullae in exposed areas are very characteristic. Repeated or continuous exposure of sensitized individual with allergen result in chronic dermatitis. Lichenification, erythematous plaques, hyperkeratosis and fissuring may develop in chronic patients. Allergic contact dermatitis is very common dermatologic problem in dermatology daily practice. A diagnosis of contact dermatitis requires the careful consideration of patient history, physical examination and patch testing. The knowledge of the clinical features of the skin reactions to various contactans is important to make a correct diagnosis of contact dermatitis. It can be seen in every age, in children textile product, accessories and touch products are common allergens, while in adults allergic contact dermatitis may be related with topical medicaments. The contact pattern of contact dermatitis depends on fashion and local traditions as well. The localization of allergic reaction should be evaluated and patients' occupation and hobbies should be asked. The purpose of this review is to introduce to our collaques up dated allergic contact dermatitis literatures both in Turkey and in the World.
A comparison of chemical shift sensitivity of trifluoromethyl tags: optimizing resolution in {sup 19}F NMR studies of proteins
Ye, Libin; Larda, Sacha Thierry; Frank Li, Yi Feng [University of Toronto, UTM, Department of Chemistry (Canada); Manglik, Aashish [Stanford University School of Medicine, Department of Molecular and Cellular Physiology (United States); Prosser, R. Scott, E-mail: scott.prosser@utoronto.ca [University of Toronto, UTM, Department of Chemistry (Canada)
The elucidation of distinct protein conformers or states by fluorine ({sup 19}F) NMR requires fluorinated moieties whose chemical shifts are most sensitive to subtle changes in the local dielectric and magnetic shielding environment. In this study we evaluate the effective chemical shift dispersion of a number of thiol-reactive trifluoromethyl probes [i.e. 2-bromo-N-(4-(trifluoromethyl)phenyl)acetamide (BTFMA), N-(4-bromo-3-(trifluoromethyl)phenyl)acetamide (3-BTFMA), 3-bromo-1,1,1-trifluoropropan-2-ol (BTFP), 1-bromo-3,3,4,4,4-pentafluorobutan-2-one (BPFB), 3-bromo-1,1,1-trifluoropropan-2-one (BTFA), and 2,2,2-trifluoroethyl-1-thiol (TFET)] under conditions of varying polarity. In considering the sensitivity of the {sup 19}F NMR chemical shift to the local environment, a series of methanol/water mixtures were prepared, ranging from relatively non-polar (MeOH:H{sub 2}OÂ =Â 4) to polar (MeOH:H{sub 2}OÂ =Â 0.25). {sup 19}F NMR spectra of the tripeptide, glutathione ((2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl] -2-sulfanylethyl]carbamoyl}butanoic acid), conjugated to each of the above trifluoromethyl probes, revealed that the BTFMA tag exhibited a significantly greater range of chemical shift as a function of solvent polarity than did either BTFA or TFET. DFT calculations using the B3LYP hybrid functional and the 6-31G(d,p) basis set, confirmed the observed trend in chemical shift dispersion with solvent polarity.
Changes in mechanical, chemical, and thermal sensitivity of the cornea after topical application of nonsteroidal anti-inflammatory drugs.
Acosta, M Carmen; Berenguer-Ruiz, Leticia; García-Gálvez, Alberto; Perea-Tortosa, David; Gallar, Juana; Belmonte, Carlos
In addition to their well-known anti-inflammatory actions, some of the nonsteroidal anti-inflammatory drugs (NSAIDs) appear to have an analgesic effect. In human subjects, the changes in threshold and intensity of sensations evoked by mechanical, chemical, and thermal stimulation of the cornea induced by topical administration of two commercial NSAIDs, diclofenac sodium (Voltaren; Novartis, Basel, Switzerland) and flurbiprofen (Ocuflur; Allergan, Irvine, CA), were studied. Corneal sensitivity was measured in 10 young, healthy subjects with a gas esthesiometer. Chemical (10%-70% CO2 in air), mechanical (0-264 mL/min), and thermal (corneal temperature changes between -4.5 degrees C and +3 degrees C around the normal value) stimuli were applied to the center of the cornea. The intensity and perceived magnitude of the psychophysical attributes of the evoked sensation were scored at the end of the pulse in a 10-cm, continuous visual analog scale (VAS). The threshold was expressed as the stimulus intensity that evoked a VAS score >0.5. Sensitivity was measured in both eyes of each subject on two separate days, one without treatment and the other 30 minutes after topical application of 0.03% flurbiprofen (seven subjects) or 0.1% diclofenac sodium (six subjects). Diclofenac attenuated significantly all the sensation parameters evoked by high-intensity mechanical, chemical, and thermal stimuli. Flurbiprofen produced a slight reduction of the sensations evoked by mechanical and chemical stimulation that became significant only for the irritation caused by chemical stimuli of maximum intensity (70% CO2). None of the drugs modified significantly the detection threshold of the different stimuli. Flurbiprofen had a very limited effect on sensations evoked by corneal stimulation, whereas diclofenac reduced the intensity of sensations evoked by stimuli of different modality, suggesting a mild local anesthetic effect of this drug on all types of corneal sensory fibers. Such
Local lymph node activation in rats after dermal application of the sensitizers 2,4-dinitrochlorobenzene and trimellitic anhydride
Arts, J.H.E.; Dröge, S.C.M.; Bloksma, N.; Kuper, C.F.
Five rat strains were compared for their performance in the local lymph node assay (LLNA) a promising test system for the identification of the skin-sensitizing potential of chemicals in the mouse. The contact sensitizer 2,4-dinitrochlorobenzene (DNCB) and the contact and respiratory sensitizer
Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.
Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki
A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.
Chemical cues from fish heighten visual sensitivity in larval crabs through changes in photoreceptor structure and function.
Charpentier, Corie L; Cohen, Jonathan H
Several predator avoidance strategies in zooplankton rely on the use of light to control vertical position in the water column. Although light is the primary cue for such photobehavior, predator chemical cues or kairomones increase swimming responses to light. We currently lack a mechanistic understanding for how zooplankton integrate visual and chemical cues to mediate phenotypic plasticity in defensive photobehavior. In marine systems, kairomones are thought to be amino sugar degradation products of fish body mucus. Here, we demonstrate that increasing concentrations of fish kairomones heightened sensitivity of light-mediated swimming behavior for two larval crab species (Rhithropanopeus harrisii and Hemigrapsus sanguineus). Consistent with these behavioral results, we report increased visual sensitivity at the retinal level in larval crab eyes directly following acute (1-3 h) kairomone exposure, as evidenced electrophysiologically from V-log I curves and morphologically from wider, shorter rhabdoms. The observed increases in visual sensitivity do not correspond with a decline in temporal resolution, because latency in electrophysiological responses actually increased after kairomone exposure. Collectively, these data suggest that phenotypic plasticity in larval crab photobehavior is achieved, at least in part, through rapid changes in photoreceptor structure and function. © 2015. Published by The Company of Biologists Ltd.
Abdelkader, Mohamed; Metzger, Swen; Steil, Benedikt; Klingmü ller, Klaus; Tost, Holger; Pozzer, Andrea; Stenchikov, Georgiy L.; Barrie, Leonard; Lelieveld, Jos
We present a sensitivity study on transatlantic dust transport, a process which has many implications for the atmosphere, the ocean and the climate. We investigate the impact of key processes that control the dust outflow, i.e., the emission flux
Sensitivity analysis of large system of chemical kinetic parameters for engine combustion simulation
Hsieh, H; Sanz-Argent, J; Petitpas, G; Havstad, M; Flowers, D
In this study, the authors applied the state-of-the art sensitivity methods to downselect system parameters from 4000+ to 8, (23000+ -> 4000+ -> 84 -> 8). This analysis procedure paves the way for future works: (1) calibrate the system response using existed experimental observations, and (2) predict future experiment results, using the calibrated system.
Changes in the pattern of sensitization to common contact allergens in denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies
Johansen, J d; Menné, T; Christophersen, J
sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation......The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period. Attention is given to possible effects of preventive strategies introduced in Denmark regarding nickel and chromate...... was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0...
Sensitivity analysis of the Gupta and Park chemical models on the heat flux by DSMC and CFD codes
Morsa, Luigi; Festa, Giandomenico; Zuppardi, Gennaro
The present study is the logical continuation of a former paper by the first author in which the influence of the chemical models by Gupta and by Park on the computation of heat flux on the Orion and EXPERT capsules was evaluated. Tests were carried out by the direct simulation Monte Carlo code DS2V and by the computational fluiddynamic (CFD) code H3NS. DS2V implements the Gupta model, while H3NS implements the Park model. In order to compare the effects of the chemical models, the Park model was implemented also in DS2V. The results showed that DS2V and H3NS compute a different composition both in the flow field and on the surface, even using the same chemical model (Park). Furthermore DS2V computes, by the two chemical models, different compositions in the flow field but the same composition on the surface, therefore the same heat flux. In the present study, in order to evaluate the influence of these chemical models also in a CFD code, the Gupta and the Park models have been implemented in FLUENT. Tests by DS2V and by FLUENT, have been carried out for the EXPERT capsule at the altitude of 70 km and with velocity of 5000 m/s. The capsule experiences a hypersonic, continuum low density regime. Due to the energy level of the flow, the vibration equation, lacking in the original version of FLUENT, has been implemented. The results of the heat flux computation verify that FLUENT is quite sensitive to the Gupta and to the Park chemical models. In fact, at the stagnation point, the percentage difference between the models is about 13%. On the opposite the DS2V results by the two models are practically equivalent.
A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.
Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan
In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.
LaF3 thin films as chemically sensitive material for semiconductor sensors
Szeponik, J.; Moritz, W.; Sellam, F.
A new kind of semiconductor based fluoride sensor was prepared by growing thin polycrystalline LaF 3 films directly on silicon substrates using vacuum vapour deposition technique. The EICS (Electrolyte Ion Conductor Semiconductor) structure was investigated by means of impedance spectroscopy, C-V measurements and exchange measurements with labeled ions ( 18 F). Whereas charge and potential conditions at the LaF 3 /electrolyte interface are governed by the fast fluoride exchange the LaF 3 bulk and the blocked Si/LaF 3 interface determine the electrical behavior. Although the Si/LaF 3 contact is not reversible the potential stability of the EICS structure is surprisingly high. Additional results at epitaxial LaF 3 layers, prepared by MBE, were taken into account for comparision with those at polycrystalline layers. (orig.)
Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction.
Escala, D M; Muñuzuri, A P; De Wit, A; Carballido-Landeira, J
The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity. We characterize this coupled reactive system showing the effects of changes in the initial concentrations of the polymer and in the chemical reagents on the induction time, the magnitude of the pH variations and the temporal modifications of the viscosity.
Chemical modification of conventional cancer radiotherapy. Tumor sensitization combined with normal tissue protection
Kagiya, Tsutomu
Nitrotriazole radiosensitizer, Sanazole (AK-2123, N-(2'-methoxyethyl)-2-(3''-nitro-1''-triazolyl) acetamide) developed by Kyoto University group was studied by 18 groups of 7 countries on fundamental aspects and clinical studies by 30 groups of 12 countries, and reported its effects on tumor sensitization of conventional cancer radiotherapy. On the other hand, the glucosides of vitamin C (Ascorbic acid glucoside, (AsAG) and water soluble derivative of vitamin-E (α-tocopherol glucoside, TMG) developed by Kyoto University group were studied fundamentally by 4 groups of 4 countries and clinically by 2 groups of 2 countries, and reported their effects on normal tissue protection in cancer treatments. These two studies of tumor sensitization and normal tissue protection were proposed as an advanced strategy of conventional cancer radiotherapy. (author)
A randomised, placebo-controlled trial of transcranial pulsed electromagnetic fields in patients with multiple chemical sensitivity
Tran, Marie Thi Dao; Skovbjerg, Sine; Arendt-Nielsen, Lars
was the Life Impact Scale (LIS) of the Quick Environmental Exposure and Sensitivity Inventory (QEESI). Secondary outcomes were the Symptom Severity Scale (SSS) and the Chemical Intolerance Scale of QEESI. RESULTS: A total of 39 participants were randomised to PEMF or placebo treatment. No significant...... difference was observed on QEESI LIS between groups with a mean change score of -5.9 in the PEMF group compared with -1.5 in the placebo group (p=0.35, effect size=-0.31). However, a significant decrease was detected on QEESI SSS within and between groups with a mean change score of -11.3 in the PEMF group...
Mechanisms involved in the chemical inhibition of the Eosin-sensitized photooxidation of trypsin
Rizzuto, F.; Spikes, J.D.
A large series of compounds was screened for ability to protect trypsin from eosin-sensitized photodynamic inactivation. Eosin-sensitized photooxidation reactions of this type typically proceed via the triplet state of the dye and often involve singlet state oxygen as the oxidizing entity. In order to determine the mechanisms by which trypsin is protected from photoinactivation, a number of good protective agents (inhibitors) and some non-protective agents were selected for more detailed flash photolysis studies. Good inhibitors such as p-phenylenediamine, n-propyl gallate, serotonin creatinine sulfate and p-toluenediamine competed efficiently with oxygen and with trypsin for reaction with the triplet state of eosin. The inhibitors were shown to quench triplet eosin to the ground state and/or reduce triplet eosin to form the semireduced eosin radical and an oxidized form of the inhibitor. In the latter case, oxidized inhibitor could react by a reverse electron transfer reaction with the semireduced eosin radical to regenerate ground state eosin and the inhibitor. The good inhibitors also competed effectively with trypsin for oxidation by semioxidized eosin, thus giving another possible protective mechanism. Non-inhibitors such as halogen ions and the paramagnetic ions Co/sup + +/, Cu/sup + +/ and Mn/sup + +/ reacted only slowly with triplet and with semioxidized eosin. The primary pathway for the eosin-sensitized photooxidation of trypsin at pH 8.0 involved singlet oxygen, although semioxidized eosin may also participate.
Highly sensitive and selective room-temperature NO_2 gas sensor based on bilayer transferred chemical vapor deposited graphene
Seekaew, Yotsarayuth; Phokharatkul, Ditsayut; Wisitsoraat, Anurat; Wongchoosuk, Chatchawal
Highlights: • Simple and low-cost fabrication of bilayer graphene gas sensor was presented. • Layer effects of graphene on NO_2 gas-sensing properties were investigated. • Bilayer graphene sensor exhibited a high linear NO_2 sensitivity of 1.409 ppm"−"1. • The NO_2-sensing mechanisms based on band diagram were highlighted. - Abstract: This work presents a highly sensitive room-temperature gas sensor based on bilayer graphene fabricated by an interfacial transfer of chemical vapor deposited graphene onto nickel interdigitated electrodes. Scanning electron microscopic and Raman spectroscopic characterizations confirm the presence of graphene on interdigitated nickel electrodes with varying numbers of graphene layers. The NO_2 detection performances of bilayer graphene gas sensor have been investigated in comparison with those of monolayer and multilayer graphene gas sensors at room temperature. From results, the bilayer graphene gas sensor exhibits higher response, sensitivity and selectivity to NO_2 than monolayer and multilayer graphene. The sensitivity of bilayer graphene gas sensor is 1.409 ppm"−"1 towards NO_2 over a concentration range of 1–25 ppm, which is more than twice higher than that of monolayer graphene. The NO_2-sensing mechanism of graphene sensing film has been explained based on the direct charge transfer process due to the adsorption of NO_2 molecules.
Effect of genes controlling radiation sensitivity on chemical mutagenesis in yeast
Ultraviolet radiation, x radiation, nitrogen mustard, methyl methanesulfonate, and dimethyl sulfate were found to revert all the tester strains with the same efficiency or without any dependence on simple types of base-pair changes, and it was concluded that these mutagens were nonspecific in the types of base-pair changes produced. The cycl-131 tester was used in studies designed to determine the genetic control of mutation induction using a variety of mutagens. The rad 6 and rad g genes greatly reduce the frequency of chemically induced reversion of cycl-131
Repetitive exposure to a chemical agent can induce an immune reaction in inherently susceptible individuals that leads to skin sensitization. Although many chemicals have been reported as skin sensitizers, there have been very few rigorously validated QSAR models with defined applicability domains (AD) that were developed using a large group of chemically diverse compounds. In this study, we have aimed to compile, curate, and integrate the largest publicly available dataset related to chemically-induced skin sensitization, use this data to generate rigorously validated and QSAR models for skin sensitization, and employ these models as a virtual screening tool for identifying putative sensitizers among environmental chemicals. We followed best practices for model building and validation implemented with our predictive QSAR workflow using random forest modeling technique in combination with SiRMS and Dragon descriptors. The Correct Classification Rate (CCR) for QSAR models discriminating sensitizers from non-sensitizers were 71–88% when evaluated on several external validation sets, within a broad AD, with positive (for sensitizers) and negative (for non-sensitizers) predicted rates of 85% and 79% respectively. When compared to the skin sensitization module included in the OECD QSAR toolbox as well as to the skin sensitization model in publicly available VEGA software, our models showed a significantly higher prediction accuracy for the same sets of external compounds as evaluated by Positive Predicted Rate, Negative Predicted Rate, and CCR. These models were applied to identify putative chemical hazards in the ScoreCard database of possible skin or sense organ toxicants as primary candidates for experimental validation. PMID:25560674
Precisely Controlled Ultrathin Conjugated Polymer Films for Large Area Transparent Transistors and Highly Sensitive Chemical Sensors.
Khim, Dongyoon; Ryu, Gi-Seong; Park, Won-Tae; Kim, Hyunchul; Lee, Myungwon; Noh, Yong-Young
A uniform ultrathin polymer film is deposited over a large area with molecularlevel precision by the simple wire-wound bar-coating method. The bar-coated ultrathin films not only exhibit high transparency of up to 90% in the visible wavelength range but also high charge carrier mobility with a high degree of percolation through the uniformly covered polymer nanofibrils. They are capable of realizing highly sensitive multigas sensors and represent the first successful report of ethylene detection using a sensor based on organic field-effect transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Chemical Selectivity and Sensitivity of a 16-Channel Electronic Nose for Trace Vapour Detection
Drago Strle
Full Text Available Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10+12 N2 molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H2S, HCN, FeS, NH3, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10+7 times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods.
[News on occupational contact dermatitis].
Crépy, Marie-Noëlle; Bensefa-Colas, Lynda
Contact dermatitis--irritant contact dermatitis, allergic contact dermatitis and protein contact dermatitis--are the most common occupational skin diseases, most often localized to the hands. Contact urticaria is rarer The main occupational irritants are wet work, detergents and disinfectants, cutting oils, and solvents. The main occupational allergens are rubber additives, metals (chromium, nickel, cobalt), plastics (epoxy resins, acrylic), biocides and plants. Diagnosis is based on clinical examination, medical history and allergy testing. For a number of irritating or sensitizing agents, irritant or allergic dermatitis can be notified as occupational diseases. The two main prevention measures are reducing skin contact with irritants and complete avoidance of skin contact with offending allergens.
Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization
Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R 2 = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q 2 ext = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin sensitization and
Alves, Vinicius M. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Muratov, Eugene [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Laboratory of Theoretical Chemistry, A.V. Bogatsky Physical–Chemical Institute NAS of Ukraine, Odessa 65080 (Ukraine); Fourches, Denis [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Strickland, Judy; Kleinstreuer, Nicole [ILS/Contractor supporting the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), P.O. Box 13501, Research Triangle Park, NC 27709 (United States); Andrade, Carolina H. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Tropsha, Alexander, E-mail: alex_tropsha@unc.edu [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States)
Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R{sup 2} = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q{sup 2}{sub ext} = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin
Sensitivity of the deep-sea amphipod Eurythenes gryllus to chemically dispersed oil.
Olsen, Gro Harlaug; Coquillé, Nathalie; Le Floch, Stephane; Geraudie, Perrine; Dussauze, Matthieu; Lemaire, Philippe; Camus, Lionel
In the context of an oil spill accident and the following oil spill response, much attention is given to the use of dispersants. Dispersants are used to disperse an oil slick from the sea surface into the water column generating a cloud of dispersed oil droplets. The main consequence is an increasing of the sea water-oil interface which induces an increase of the oil biodegradation. Hence, the use of dispersants can be effective in preventing oiling of sensitive coastal environments. Also, in case of an oil blowout from the seabed, subsea injection of dispersants may offer some benefits compared to containment and recovery of the oil or in situ burning operation at the sea surface. However, biological effects of dispersed oil are poorly understood for deep-sea species. Most effects studies on dispersed oil and also other oil-related compounds have been focusing on more shallow water species. This is the first approach to assess the sensitivity of a macro-benthic deep-sea organism to dispersed oil. This paper describes a toxicity test which was performed on the macro-benthic deep-sea amphipod (Eurythenes gryllus) to determine the concentration causing lethality to 50% of test individuals (LC50) after an exposure to dispersed Brut Arabian Light (BAL) oil. The LC50 (24 h) was 101 and 24 mg L(-1) after 72 h and 12 mg L(-1) at 96 h. Based on EPA scale of toxicity categories to aquatic organisms, an LC50 (96 h) of 12 mg L(-1) indicates that the dispersed oil was slightly to moderately toxic to E. gryllus. As an attempt to compare our results to others, a literature study was performed. Due to limited amount of data available for dispersed oil and amphipods, information on other crustacean species and other oil-related compounds was also collected. Only one study on dispersed oil and amphipods was found, the LC50 value in this study was similar to the LC50 value of E. gryllus in our study. Since toxicity data are important input to risk assessment and net environmental
Glucose metabolism-weighted imaging with chemical exchange-sensitive MRI of 2-deoxyglucose (2DG) in brain: Sensitivity and biological sources.
Jin, Tao; Mehrens, Hunter; Wang, Ping; Kim, Seong-Gi
Recent proof-of-principle studies have demonstrated the feasibility of measuring the uptake and metabolism of non-labeled 2-deoxy-D-glucose (2DG) by a chemical exchange-sensitive spin-lock (CESL) MRI approach. In order to gain better understanding of this new approach, we performed dynamic in vivo CESL MRI on healthy rat brains with an intravenous injection of 2DG under various conditions at 9.4T. For three 2DG doses of 0.25, 0.5 and 1g/kg, we found that 2DG-CESL signals increased linearly with injection dose at the initial (40min) suggesting time-dependent differential weightings of 2DG transport and metabolism. Remaining 2DG-CESL studies were performed with 0.25g/kg 2DG. Since a higher isoflurane level reduces glucose metabolism and increases blood flow, 2DG-CESL was measured under 0.5%, 1.5% and 2.2% isoflurane. The 2DG-CESL signal was reduced at higher isoflurane levels correlating well with the 2DG phosphorylation in the intracellular space. To detect regional heterogeneities of glucose metabolism, 2DG-CESL with 0.33×0.33×1.50mm 3 resolution was obtained, which indeed showed a higher response in the cortex compared to the corpus callosum. Lastly, unlike CESL MRI with the injection of non-transportable mannitol, the 2DG-CESL response decreased with an increased spin-lock pulse power confirming that 2DG-CESL is dominated by chemical exchange processes in the extravascular space. Taken together, our results showed that 2DG-CESL MRI signals mainly indicate glucose transport and metabolism and may be a useful biomarker for metabolic studies of normal and diseased brains. Copyright © 2016 Elsevier Inc. All rights reserved.
Investigation of Electrochemically Deposited and Chemically Reduced Platinum Nanostructured Thin Films as Counter Electrodes in Dye-Sensitized Solar Cells
Chih-Hung Tsai
Full Text Available In this paper, we demonstrated that platinum (Pt counter electrodes (CEs fabricated using electrochemical deposition and chemical reduction can replace conventional high-temperature thermally decomposed Pt electrodes. In this study, Pt electrodes were fabricated using thermal decomposition, electrochemical deposition, and chemical reduction, and the influence of the different Pt counter electrodes on the efficiency of the dye-sensitized solar cells (DSSCs was analyzed. The properties of the various Pt CEs were analyzed using scanning electron microscopy (SEM, surface area analysis, X-ray diffraction (XRD, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. DSSCs with various Pt CEs were characterized using current density-voltage (J-V, incident photo-current conversion efficiency (IPCE, and EIS measurements. The results show that the power conversion efficiencies of these three types of DSSC devices were between 7.43% and 7.72%. The DSSCs based on the Pt electrode fabricated through electrochemical deposition exhibited the optimal power conversion efficiency. Because the processes of electrochemical deposition and chemical reduction do not require high-temperature sintering, these two methods are suitable for the fabrication of Pt on flexible plastic substrates.
Chemical sensitive interfacial free volume studies of nanophase Al-rich alloys
Lechner, W.; Puff, W.; Wuerschum, R.; Wilde, G.
Full text: Al-based nanocrystalline alloys have attracted substantial interest due to their outstanding mechanical properties. These alloys can be obtained by crystallization of melt-spun amorphous precursors or by grain refinement upon repeated cold-rolling of elemental layers. For both synthesis routes, the nanocrystallization process is sensitively affected by interfacial chemistry and free volumes. In order to contribute to an atomistic understanding of the interfacial structure and processes during nanocrystallization, the present work deals with studies of interfacial free volumes by means of positron-annihilation-spectroscopy. In addition to positron lifetime spectroscopy which yields information on the size of free volumes, coincident Doppler broadening of the positron-electron annihilation photons is applied as novel technique for studying the chemistry of interfaces in nanophase materials on an atomistic scale. Al-rich alloys of the above mentioned synthesis routes were studied in this work. (author)
A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts
Ahmed A. Ibrahim
Full Text Available Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE. Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM−1·cm−2, a lower limit of detection at 7.8 µM, a regression coefficient (R2 of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM−1·cm−2, an experimental Limit of detection (LOD of 0.125 mM, and a linear dynamic range (LDR of 1.0 mM–5.0 mM were observed for the fabricated picric acid sensor.
Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)
Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd
The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier
Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat [Faculty of Science and Technology, University Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Amin, Mohd. Cairul Iqbal Mohd [Faculty of Pharmacy, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia)
The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.
Assessing the sensitivity of benzene cluster cation chemical ionization mass spectrometry toward a wide array of biogenic volatile organic compounds
Lavi, Avi; Vermeuel, Michael; Novak, Gordon; Bertram, Timothy
Chemical ionization mass spectrometry is a real-time, sensitive and selective measurement technique for the detection of volatile organic compounds (VOCs). The benefits of CIMS technology make it highly suitable for field measurements that requires fast (10Hz and higher) response rates, such as the study of surface-atmosphere exchange processes by the eddy covariance method. The use of benzene cluster cations as a regent ion was previously demonstrated as a sensitive and selective method for the detection of select biogenic VOCs (e.g. isoprene, monoterpenes and sesquiterpenes) [Kim et al., 2016; Leibrock and Huey, 2000]. Quantitative analysis of atmospheric trace gases necessitates calibration for each analyte as a function of atmospheric conditions. We describe a custom designed calibration system, based on liquid evaporation, for determination of the sensitivity of the benzene-CIMS to a wide range of organic compounds at atmospherically relevant mixing ratios (volatile organic compounds, Atmos Meas Tech, 9(4), 1473-1484, doi:10.5194/amt-9-1473-2016. Leibrock, E., and L. G. Huey (2000), Ion chemistry for the detection of isoprene and other volatile organic compounds in ambient air, Geophys Res Lett, 27(12), 1719-1722, doi:Doi 10.1029/1999gl010804.
Gimenéz-Arnau, Elena; Andersen, K E; Bruze, M
Fragrance materials are among the most common causes of allergic contact dermatitis. The aim of this study was to identify in a perfume fragrance allergens not included in the fragrance mix, by use of bioassay-guided chemical fractionation and chemical analysis/structure-activity relationships...... (SARs). The basis for the investigation was a 45-year-old woman allergic to her own perfume. She had a negative patch test to the fragrance mix and agreed to participate in the study. Chemical fractionation of the perfume concentrate was used for repeated patch testing and/or repeated open application...
Contact stress sensor
Kotovsky, Jack [Oakland, CA
A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.
Future Needs and Recommendations in the Development of Species Sensitivity Distributions: Estimating Toxicity Thresholds for Aquatic Ecological Communities and Assessing Impacts of Chemical Exposures
A species sensitivity distribution (SSD) is a probability model of the variation of species sensitivities to a stressor, in particular chemical exposure. The SSD approach has been used as a decision support tool in environmental protection and management since the 1980s, and the ...
Nanoscopic platinum particles on TiO{sub 2}(110). STM and point-contact studies on the chemical and photosensitivity; Nanoskopische Platin-Teilchen auf TiO{sub 2}(110). STM- und Punktkontaktuntersuchungen zur chemischen und Photosensitivitaet
Koelbach, Johannes Micha
In the ultra high vacuum produced nanoscopical platinum particles on TiO{sub 2}(110)- single crystal surfaces are contacted with the tunneltip of a raster tunnel microscope, and the chemical as well as photo sensitivity of an individual hetero contact are determined. For the experiments a UHV equipment was developed, equipped with methods to the controlled preparation and surface-analytic techniques (LEED, AES and STM). Platinum is resistively evaporated and thus small platinum particles with a size of about 8nm are generated on the pure titanium dioxide surface and characterized by STM and STS. A new developed oxygen source based on zirconoxide ceramics enables in-situ experiments for undisturbed determination of current-voltage characteristics in the tunneling and contact mode. A special preamplifier with controllable range of amplification is applied. Applying a voltage to the ceramic oxygen can be let into the UHV chamber by the oxygen source and the partial pressure can be adjusted within the range of 1.10{sup -10} mbar to 1.10{sup -5} mbar. The effect of the oxygen on the electrical characteristics of the Pt/TiO{sub 2}-contacts was proven. The clear dependence of the current-voltage characteristics on the oxygen partial pressure can be explained as a result of interface states due to the dissociation and adsorption of the oxygen, which determine the electrical characteristic of the contact. Schottky barriere heights and quality parameters were determined and compared with values of macroscopic surface contacts. For the investigations of the photo sensitivity a special STM head was developed, which enables the coupling of laser light with a wavelength of 413.1 nm. Irradiation of the nanoscopical Pt/TiO{sub 2}-contacts changes the current-voltage characteristics as well. The results of the power-dependent measurements refer to a temperature effect, that dominates the photoelectric effect. The combined power-and oxygen partial pressure dependent measurements are
Surface Alpha Interactions in P-Type Point-Contact HPGe Detectors: Maximizing Sensitivity of 76Ge Neutrinoless Double-Beta Decay Searches
Gruszko, Julieta
Though the existence of neutrino oscillations proves that neutrinos must have non-zero mass, Beyond-the-Standard-Model physics is needed to explain the origins of that mass. One intriguing possibility is that neutrinos are Majorana particles, i.e., they are their own anti-particles. Such a mechanism could naturally explain the observed smallness of the neutrino masses, and would have consequences that go far beyond neutrino physics, with implications for Grand Unification and leptogenesis. If neutrinos are Majorana particles, they could undergo neutrinoless double-beta decay (0nBB), a hypothesized rare decay in which two antineutrinos annihilate one another. This process, if it exists, would be exceedingly rare, with a half-life over 1E25 years. Therefore, searching for it requires experiments with extremely low background rates. One promising technique in the search for 0nBB is the use of P-type point-contact (P-PC) high-purity Germanium (HPGe) detectors enriched in 76Ge, operated in large low-background arrays. This approach is used, with some key differences, by the MAJORANA and GERDA Collaborations. A problematic background in such large granular detector arrays is posed by alpha particles incident on the surfaces of the detectors, often caused by 222Rn contamination of parts or of the detectors themselves. In the MAJORANA DEMONSTRATOR, events have been observed that are consistent with energy-degraded alphas originating near the passivated surface of the detectors, leading to a potential background contribution in the region-of-interest for neutrinoless double-beta decay. However, it is also observed that when energy deposition occurs very close to the passivated surface, high charge trapping occurs along with subsequent slow charge re-release. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. Here we discuss the characteristics of these events and the development of a filter that can identify the
Dynamic contact angle cycling homogenizes heterogeneous surfaces.
Belibel, R; Barbaud, C; Mora, L
In order to reduce restenosis, the necessity to develop the appropriate coating material of metallic stent is a challenge for biomedicine and scientific research over the past decade. Therefore, biodegradable copolymers of poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) were prepared in order to develop a new coating exhibiting different custom groups in its side chain and being able to carry a drug. This material will be in direct contact with cells and blood. It consists of carboxylic acid and hexylic groups used for hydrophilic and hydrophobic character, respectively. The study of this material wettability and dynamic surface properties is of importance due to the influence of the chemistry and the potential motility of these chemical groups on cell adhesion and polymer kinetic hydrolysis. Cassie theory was used for the theoretical correction of contact angles of these chemical heterogeneous surfaces coatings. Dynamic Surface Analysis was used as practical homogenizer of chemical heterogeneous surfaces by cycling during many cycles in water. In this work, we confirmed that, unlike receding contact angle, advancing contact angle is influenced by the difference of only 10% of acidic groups (%A) in side-chain of polymers. It linearly decreases with increasing acidity percentage. Hysteresis (H) is also a sensitive parameter which is discussed in this paper. Finally, we conclude that cycling provides real information, thus avoiding theoretical Cassie correction. H(10)is the most sensible parameter to %A. Copyright © 2016 Elsevier B.V. All rights reserved.
Prevalence of contact allergy in the general population: Sensitization to metals with a focus on nickel sulfate, the EDEN Fragrance Study Group
Schuttelaar, M.-L.; Ofenloch, R.; Bruze, M.; Cazzaniga, S.; Elsner, P.; Gonçalo, M.; Naldi, L.; Svensson, Å.; Diepgen, T.
Sensitization to metals is assessed mostly in clinical populations. Studies in the general population are scarce. Our objective was to determine the prevalence of metal sensitization in the general population and to determine risk factors for nickel sensitization. In five European countries (the
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Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R2=0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q2ext = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. PMID:25560673
Tomato contact dermatitis
Paulsen, Evy; Christensen, Lars P; Andersen, Klaus Ejner
The tomato plant (Solanum lycopersicum) is an important crop worldwide. Whereas immediate-type reactions to tomato fruits are well known, contact dermatitis caused by tomatoes or tomato plants is rarely reported. The aims of this study were to present new data on contact sensitization to tomato...... plants and review the literature on contact dermatitis caused by both plants and fruits. An ether extract of tomato plants made as the original oleoresin plant extracts, was used in aimed patch testing, and between 2005 and 2011. 8 of 93 patients (9%) tested positive to the oleoresin extracts....... This prevalence is in accordance with the older literature that reports tomato plants as occasional sensitizers. The same applies to tomato fruits, which, in addition, may cause protein contact dermatitis. The allergens of the plant are unknown, but both heat-stable and heat-labile constituents seem...
MOFs for the Sensitive Detection of Ammonia: Deployment of fcu-MOF Thin Films as Effective Chemical Capacitive Sensors.
Assen, Ayalew H; Yassine, Omar; Shekhah, Osama; Eddaoudi, Mohamed; Salama, Khaled N
This work reports on the fabrication and deployment of a select metal-organic framework (MOF) thin film as an advanced chemical capacitive sensor for the sensing/detection of ammonia (NH 3 ) at room temperature. Namely, the MOF thin film sensing layer consists of a rare-earth (RE) MOF (RE-fcu-MOF) deposited on a capacitive interdigitated electrode (IDE). Purposely, the chemically stable naphthalene-based RE-fcu-MOF (NDC-Y-fcu-MOF) was elected and prepared/arranged as a thin film on a prefunctionalized capacitive IDE via the solvothermal growth method. Unlike earlier realizations, the fabricated MOF-based sensor showed a notable detection sensitivity for NH 3 at concentrations down to 1 ppm, with a detection limit appraised to be around 100 ppb (at room temperature) even in the presence of humidity and/or CO 2 . Distinctly, the NDC-Y-fcu-MOF based sensor exhibited the required stability to NH 3 , in contrast to other reported MOFs, and a remarkable detection selectivity toward NH 3 vs CH 4 , NO 2 , H 2 , and C 7 H 8 . The NDC-Y-fcu-MOF based sensor exhibited excellent performance for sensing ammonia for simulated breathing system in the presence of the mixture of carbon dioxide and/or humidity (water vapor), with no major alteration in the detection signal.
Electroconvulsive therapy substantially reduces symptom severity and social disability associated with multiple chemical sensitivity: a case report.
Multiple chemical sensitivity (MCS) is a chronic nonallergic, multisymptom disorder triggered by common environmental chemicals in concentrations considered nontoxic for most individuals. The condition may lead to loss of occupation and social isolation, and no effective treatment has been reported. Electroconvulsive therapy (ECT) is a safe and effective treatment of severe depression and medical conditions such as chronic pain disorders. We report a case of a 45-year-old man with a 5-year history of MCS who had to quit his job to live a solitary life without his wife and children because of the condition. The patient had no history of psychiatric illness and no signs of clinical depression at treatment start. Over a 3-week period, he underwent a course of 8 ECTs, giving a remarkable effect on symptom severity and social functional level. After a partial symptom relapse, maintenance treatment was started with 1 ECT every second week. No memory impairment or other complications of ECT were reported at the 4-month follow-up. In this case, a substantial, positive effect on symptom severity and social disability related to MCS was obtained by an initial ECT course and maintenance treatment. Electroconvulsive therapy should be considered an option in severe and socially disabling MCS, but more studies are needed to evaluate if ECT can be recommended as a treatment in MCS.
MOFs for the Sensitive Detection of Ammonia: Deployment of fcu-MOF Thin-Films as Effective Chemical Capacitive Sensors.
Assen, Ayalew Hussen Assen
This work reports on the fabrication and deployment of a select metal-organic framework (MOF) thin film as an advanced chemical capacitive sensor for the sensing/detection of ammonia (NH3) at room temperature. Namely, the MOF thin film sensing layer consists of a rare-earth (RE) MOF (RE-fcu-MOF) deposited on a capacitive interdigitated electrode (IDE). Purposely, the chemically stable naphthalene-based RE-fcu-MOF (NDC-Y-fcu-MOF) was elected and prepared/arranged as a thin film on a pre-functionalized capacitive IDE via the solvothermal growth method. Unlike earlier realizations, the fabricated MOF-based sensor showed a notable detection sensitivity for NH3 at concentrations down to 1 ppm, with a detection limit appraised to be around 100 ppb (at room temperature) even in the presence of humidity and/or CO2. Distinctly, the NDC-Y-fcu-MOF based sensor exhibited the required stability to NH3, in contract to other reported MOFs, and a remarkable detection selectivity towards NH3 vs. CH4, NO2, H2 and C7H8. The NDC-Y-fcu-MOF based sensor exhibited excellent performance for sensing ammonia for simulated breathing system in the presence of the mixture of carbon dioxide and/or humidity (water vapor), with no major alteration in the detection signal.
Contacts to semiconductors
Tove, P.A.
Contacts to semiconductors play an important role in most semiconductor devices. These devices range from microelectronics to power components, from high-sensitivity light or radiation detectors to light-emitting of microwave-generating components. Silicon is the dominating material but compound semiconductors are increasing in importance. The following survey is an attempt to classify contact properties and the physical mechanisms involved, as well as fabrication methods and methods of investigation. The main interest is in metal-semiconductor type contacts where a few basic concepts are dealt with in some detail. (Auth.)
Anchoring molecular mechanisms to the adverse outcome pathway for skin sensitization: Analysis of existing data
Veen, J.W. van der; Soeteman-Hernández, L.G.; Ezendam, J.; Stierum, R.; Kuper, F.C.; Loveren, H. van
Allergic contact dermatitis (ACD) is a hypersensitivity immune response induced by small protein-reactive chemicals. Currently, the murine local lymph node assay (LLNA) provides hazard identification and quantitative estimation of sensitizing potency. Given the complexity of ACD, a single
Elaborate Manipulation for Sub-10 nm Hollow Catalyst Sensitized Heterogeneous Oxide Nanofibers for Room Temperature Chemical Sensors.
Jang, Ji-Soo; Choi, Seon-Jin; Koo, Won-Tae; Kim, Sang-Joon; Cheong, Jun Young; Kim, Il-Doo
Room-temperature (RT) operation sensors are constantly in increasing demand because of their low power consumption, simple operation, and long lifetime. However, critical challenges such as low sensing performance, vulnerability under highly humid state, and poor recyclability hinder their commercialization. In this work, sub-10 nm hollow, bimetallic Pt-Ag nanoparticles (NPs) were successfully formed by galvanic replacement reaction in bioinspired hollow protein templates and sensitized on the multidimensional SnO 2 -WO 3 heterojunction nanofibers (HNFs). Formation of hollow, bimetallic NPs resulted in the double-side catalytic effect, rendering both surface and inner side chemical reactions. Subsequently, SnO 2 -WO 3 HNFs were synthesized by incorporating 2D WO 3 nanosheets (NSs) with 0D SnO 2 sphere by c-axis growth inhibition effect and fluid dynamics of liquid Sn during calcination. Hierarchically assembled HNFs effectively modulate surface depletion layer of 2D WO 3 NSs by electron transfers from WO 3 to SnO 2 stemming from creation of heterojunction. Careful combination of bimetallic catalyst NPs with HNFs provided an extreme recyclability under exhaled breath (95 RH%) with outstanding H 2 S sensitivity. Such sensing platform clearly distinguished between the breath of healthy people and simulated halitosis patients.
Dry transfer of chemical-vapor-deposition-grown graphene onto liquid-sensitive surfaces for tunnel junction applications
Feng, Ying; Chen, Ke
We report a dry transfer method that can tranfer chemical vapor deposition (CVD) grown graphene onto liquid-sensitive surfaces. The graphene grown on copper (Cu) foil substrate was first transferred onto a freestanding 4 μm thick sputtered Cu film using the conventional wet transfer process, followed by a dry transfer process onto the target surface using a polydimethylsiloxane stamp. The dry-transferred graphene has similar properties to traditional wet-transferred graphene, characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and electrical transport measurements. It has a sheet resistance of 1.6 ∼ 3.4 kΩ/□, hole density of (4.1 ∼ 5.3) × 10 12 cm −2 , and hole mobility of 460 ∼ 760 cm 2 V −1 s −1 without doping at room temperature. The results suggest that large-scale CVD-grown graphene can be transferred with good quality and without contaminating the target surface by any liquid. Mg/MgO/graphene tunnel junctions were fabricated using this transfer method. The junctions show good tunneling characteristics, which demonstrates the transfer technique can also be used to fabricate graphene devices on liquid-sensitive surfaces. (paper)
Chemical bath deposition of ZnO nanowire-nanoparticle composite electrodes for use in dye-sensitized solar cells
Ku, C-H; Wu, J-J [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)
ZnO nanowire (NW)-layered basic zinc acetate (LBZA)/ZnO nanoparticle (NP) composite electrodes with different NP occupying extents have been synthesized using a simple wet-chemical route for use in dye-sensitized solar cells (DSSCs). By employing mercurochrome as the sensitizer, superior efficiencies ({eta}) of 1.27-2.37% are obtained using the ZnO NW-LBZA/ZnO NP composite electrodes composed of a 5.5 {mu}m thick NW array with different NP occupying extents in comparison with the ZnO NW DSSC ({eta} = 0.45%). It suggests that the ZnO NW-LBZA/ZnO NP composite films which possess a considerable enlarged surface area by NPs growth, without sacrificing electron transport efficiency of single-crystalline ZnO NWs at the same time, are promising photoanodes for use in DSSCs. In addition to the extent of NP occupation, the overall efficiency of the ZnO NW-LBZA/ZnO NP composite DSSC is also influenced by the thickness of the composite film as well as the LBZA fraction and the cracks within the composite. The fraction of LBZA affected by the NP growth period and post-annealing conditions is found to play a crucial role in electron transport through the composite anode. Up to now, a high efficiency DSSC of 3.2% is achieved using a mercurochrome-sensitized and 6.2 {mu}m thick NW-NP composite film.
The implications of non-linear biological oscillations on human electrophysiology for electrohypersensitivity (EHS) and multiple chemical sensitivity (MCS).
Sage, Cindy
maintenance; and resilience can be compromised. Electrohypersensitivity can be caused by successive assaults on human bioelectrochemical dynamics from exogenous electromagnetic fields (EMF) and RFR or a single acute exposure. Once sensitized, further exposures are widely reported to cause reactivity to lower and lower intensities of EMF/RFR, at which point thousand-fold lower levels can cause adverse health impacts to the electrosensitive person. Electrohypersensitivity (EHS) can be a precursor to, or linked with, multiple chemical sensitivity (MCS) based on reports of individuals who first develop one condition, then rapidly develop the other. Similarity of chemical biomarkers is seen in both conditions [histamines, markers of oxidative stress, auto-antibodies, heat shock protein (HSP), melatonin markers and leakage of the blood-brain barrier]. Low intensity pulsed microwave activation of voltage-gated calcium channels (VGCCs) is postulated as a mechanism of action for non-thermal health effects.
From individual coping strategies to illness codification: the reflection of gender in social science research on multiple chemical sensitivities (MCS).
Nadeau, Geneviève; Lippel, Katherine
Emerging fields such as environmental health have been challenged, in recent years, to answer the growing methodological calls for a finer integration of sex and gender in health-related research and policy-making. Through a descriptive examination of 25 peer-reviewed social science papers published between 1996 and 2011, we explore, by examining methodological designs and theoretical standpoints, how the social sciences have integrated gender sensitivity in empirical work on Multiple Chemical Sensitivities (MCS). MCS is a "diagnosis" associated with sensitivities to chronic and low-dose chemical exposures, which remains contested in both the medical and institutional arenas, and is reported to disproportionately affect women. We highlighted important differences between papers that did integrate a gender lens and those that did not. These included characteristics of the authorship, purposes, theoretical frameworks and methodological designs of the studies. Reviewed papers that integrated gender tended to focus on the gender roles and identity of women suffering from MCS, emphasizing personal strategies of adaptation. More generally, terminological confusions in the use of sex and gender language and concepts, such as a conflation of women and gender, were observed. Although some men were included in most of the study samples reviewed, specific data relating to men was undereported in results and only one paper discussed issues specifically experienced by men suffering from MCS. Papers that overlooked gender dimensions generally addressed more systemic social issues such as the dynamics of expertise and the medical codification of MCS, from more consistently outlined theoretical frameworks. Results highlight the place for a critical, systematic and reflexive problematization of gender and for the development of methodological and theoretical tools on how to integrate gender in research designs when looking at both micro and macro social dimensions of environmental
Chemical exchange-sensitive spin-lock MRI of glucose analog 3-O-methyl-d-glucose in normal and ischemic brain.
Glucose transport is important for understanding brain glucose metabolism. We studied glucose transport with a presumably non-toxic and non-metabolizable glucose analog, 3-O-methyl-d-glucose, using a chemical exchange-sensitive spin-lock MRI technique at 9.4 Tesla. 3-O-methyl-d-glucose showed comparable chemical exchange properties with d-glucose and 2-deoxy-d-glucose in phantoms, and higher and lower chemical exchange-sensitive spin-lock sensitivity than Glc and 2-deoxy-d-glucose in in vivo experiments, respectively. The changes of the spin-lattice relaxation rate in the rotating frame (Δ R 1 �) in normal rat brain peaked at ∼15 min after the intravenous injection of 1 g/kg 3-O-methyl-d-glucose and almost maintained a plateau for >1 h. Doses up to 4 g/kg 3-O-methyl-d-glucose were linearly correlated with Δ R 1 �. In rats with focal ischemic stroke, chemical exchange-sensitive spin-lock with 3-O-methyl-d-glucose injection at 1 h after stroke onset showed reduced Δ R 1 � in the ischemic core but higher Δ R 1 � in the peri-core region compared to normal tissue, which progressed into the ischemic core at 3 h after stroke onset. This suggests that the hyper-chemical exchange-sensitive spin-lock region observed at 1 h is the ischemic penumbra at-risk of infarct. In summary, 3-O-methyl-d-glucose-chemical exchange-sensitive spin-lock can be a sensitive MRI technique to probe the glucose transport in normal and ischemic brains.
Electric contact arcing
Cuthrell, R.E.
Electrical contacts must function properly in many types of components used in nuclear weapon systems. Design, application, and testing of these components require detailed knowledge of chemical and physical phenomena associated with stockpile storage, stockpile testing, and operation. In the past, investigation of these phenomena has led to significant discoveries on the effects of surface contaminants, friction and wear, and the mechanics of closure on contact performance. A recent investigation of contact arcing phenomena which revealed that, preceding contact closure, arcs may occur at voltages lower than had been previously known is described. This discovery is important, since arcing may damage contacts, and repetitive testing of contacts performed as part of a quality assurance program might produce cumulative damage that would yield misleading life-test data and could prevent proper operation of the contacts at some time in the future. This damage can be avoided by determining the conditions under which arcing occurs, and ensuring that these conditions are avoided in contact testing
Sensitivity of Global Methane Bayesian Inversion to Surface Observation Data Sets and Chemical-Transport Model Resolution
Lew, E. J.; Butenhoff, C. L.; Karmakar, S.; Rice, A. L.; Khalil, A. K.
Methane is the second most important greenhouse gas after carbon dioxide. In efforts to control emissions, a careful examination of the methane budget and source strengths is required. To determine methane surface fluxes, Bayesian methods are often used to provide top-down constraints. Inverse modeling derives unknown fluxes using observed methane concentrations, a chemical transport model (CTM) and prior information. The Bayesian inversion reduces prior flux uncertainties by exploiting information content in the data. While the Bayesian formalism produces internal error estimates of source fluxes, systematic or external errors that arise from user choices in the inversion scheme are often much larger. Here we examine model sensitivity and uncertainty of our inversion under different observation data sets and CTM grid resolution. We compare posterior surface fluxes using the data product GLOBALVIEW-CH4 against the event-level molar mixing ratio data available from NOAA. GLOBALVIEW-CH4 is a collection of CH4 concentration estimates from 221 sites, collected by 12 laboratories, that have been interpolated and extracted to provide weekly records from 1984-2008. Differently, the event-level NOAA data records methane mixing ratios field measurements from 102 sites, containing sampling frequency irregularities and gaps in time. Furthermore, the sampling platform types used by the data sets may influence the posterior flux estimates, namely fixed surface, tower, ship and aircraft sites. To explore the sensitivity of the posterior surface fluxes to the observation network geometry, inversions composed of all sites, only aircraft, only ship, only tower and only fixed surface sites, are performed and compared. Also, we investigate the sensitivity of the error reduction associated with the resolution of the GEOS-Chem simulation (4°×5° vs 2°×2.5°) used to calculate the response matrix. Using a higher resolution grid decreased the model-data error at most sites, thereby
Can We Make Cosmetic Contact Allergy History?
David Basketter
Full Text Available Chemical allergy is of considerable importance to the toxicologist, who, amongst other things, has the responsibility of identifying and characterizing the skin (and respiratory sensitizing potential of chemicals, and estimating the risk they pose to human health. Allergic contact dermatitis (ACD is to a large extent a preventable disease. Although quantitative risk assessment (QRA for contact allergy can be performed, it is reasonable to ask why the burden of the skin disease ACD appears to remain stubbornly high, and in particular, that the general level of ACD to sensitizing ingredients found in cosmetics has not fallen noticeably over recent decades; some could argue that it has increased. In this review, this conundrum is addressed, considering whether and to what extent the prevalence of cosmetic allergy is truly unchanged, whether the predicted test methods and potency estimations are sufficiently precise and how proposed changes to the QRA process (i.e., cumulative exposure may ameliorate the situation. Improved and more widespread use of risk assessment, better education of risk assessors, better post-marketing surveillance and monitoring of dermatology clinic feedback to improve QRA, all together could help to "make contact allergy history�.
Footwear contact dermatitis from dimethyl fumarate.
Švecová, Danka; Šimaljakova, Maria; Doležalová, Anna
Dimethyl fumarate (DMF) is an effective inhibitor of mold growth. In very low concentrations, DMF is a potent sensitizer that can cause severe allergic contact dermatitis (ACD). It has been identified as the agent responsible for furniture contact dermatitis in Europe. The aim of this study was to evaluate patients in Slovakia with footwear ACD associated with DMF, with regard to clinical manifestations, patch test results, and results of chemical analysis of their footwear. Nine patients with suspected footwear contact dermatitis underwent patch testing with the following allergens: samples of their own footwear, commercial DMF, the European baseline, shoe screening, textile and leather dye screening, and industrial biocides series. The results were recorded according to international guidelines. The content of DMF in footwear and anti-mold sachets was analyzed using gas chromatography and mass spectrometry. Acute ACD was observed in nine Caucasian female patients. All patients developed delayed sensitization, as demonstrated by positive patch testing using textile footwear lining. Seven patients were patch tested with 0.1% DMF, and all seven were positive. Chemical analysis of available footwear showed that DMF was present in very high concentrations (25-80 mg/Kg). Dimethyl fumarate is a new footwear allergen and was responsible for severe ACD in our patients. To avoid an increase in the number of cases, the already approved European preventive measures should be accepted and commonly employed. © 2013 The International Society of Dermatology.
Chemical-exchange-sensitive MRI of amide, amine and NOE at 9.4Â T versus 15.2Â T.
Chung, Julius Juhyun; Choi, Wonmin; Jin, Tao; Lee, Jung Hee; Kim, Seong-Gi
Chemical exchange (CE)-sensitive MRI benefits greatly from stronger magnetic fields; however, field effects on CE-sensitive imaging have not yet been studied well in vivo. We have compared CE-sensitive Z-spectra and maps obtained at the fields of 9.4 T and 15.2 T in phantoms and rats with off-resonance chemical-exchange-sensitive spin lock (CESL), which is similar to conventional chemical exchange saturation transfer. At higher fields, the background peak at water resonance has less spread and the exchange rate relative to chemical shift decreases, thus CESL intensity is dependent on B 0 . For the in vivo amide and nuclear Overhauser enhancement (NOE) composite resonances of rat brains, intensities were similar for both magnetic fields, but effective amide proton transfer and NOE values obtained with three-point quantification or a curve fitting method were larger at 15.2 T due to the reduced spread of attenuation at the direct water resonance. When using intermediate exchange-sensitive irradiation parameters, the amine proton signal was 65% higher at 15.2 T than at 9.4 T due to a reduced ratio of exchange rate to chemical shift. In summary, increasing magnetic field provides enhancements to CE-sensitive signals in the intermediate exchange regime and reduces contamination from background signals in the slow exchange regime. Consequently, ultrahigh magnetic field is advantageous for CE-sensitive MRI, especially for amine and hydroxyl protons. Copyright © 2017 John Wiley & Sons, Ltd.
Sample handling in surface sensitive chemical and biological sensing: a practical review of basic fluidics and analyte transport.
Orgovan, Norbert; Patko, Daniel; Hos, Csaba; Kurunczi, Sándor; Szabó, Bálint; Ramsden, Jeremy J; Horvath, Robert
This paper gives an overview of the advantages and associated caveats of the most common sample handling methods in surface-sensitive chemical and biological sensing. We summarize the basic theoretical and practical considerations one faces when designing and assembling the fluidic part of the sensor devices. The influence of analyte size, the use of closed and flow-through cuvettes, the importance of flow rate, tubing length and diameter, bubble traps, pressure-driven pumping, cuvette dead volumes, and sample injection systems are all discussed. Typical application areas of particular arrangements are also highlighted, such as the monitoring of cellular adhesion, biomolecule adsorption-desorption and ligand-receptor affinity binding. Our work is a practical review in the sense that for every sample handling arrangement considered we present our own experimental data and critically review our experience with the given arrangement. In the experimental part we focus on sample handling in optical waveguide lightmode spectroscopy (OWLS) measurements, but the present study is equally applicable for other biosensing technologies in which an analyte in solution is captured at a surface and its presence is monitored. Explicit attention is given to features that are expected to play an increasingly decisive role in determining the reliability of (bio)chemical sensing measurements, such as analyte transport to the sensor surface; the distorting influence of dead volumes in the fluidic system; and the appropriate sample handling of cell suspensions (e.g. their quasi-simultaneous deposition). At the appropriate places, biological aspects closely related to fluidics (e.g. cellular mechanotransduction, competitive adsorption, blood flow in veins) are also discussed, particularly with regard to their models used in biosensing. Copyright © 2014 Elsevier B.V. All rights reserved.
Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 2: Base Case and Sensitivity Analysis
Zhao, Zhenlong
Part 1 (10.1021/ef3014103) of this series describes a new rotary reactor for gas-fueled chemical-looping combustion (CLC), in which, a solid wheel with microchannels rotates between the reducing and oxidizing streams. The oxygen carrier (OC) coated on the surfaces of the channels periodically adsorbs oxygen from air and releases it to oxidize the fuel. A one-dimensional model is also developed in part 1 (10.1021/ef3014103). This paper presents the simulation results based on the base-case design parameters. The results indicate that both the fuel conversion efficiency and the carbon separation efficiency are close to unity. Because of the relatively low reduction rate of copper oxide, fuel conversion occurs gradually from the inlet to the exit. A total of 99.9% of the fuel is converted within 75% of the channel, leading to 25% redundant length near the exit, to ensure robustness. In the air sector, the OC is rapidly regenerated while consuming a large amount of oxygen from air. Velocity fluctuations are observed during the transition between sectors because of the complete reactions of OCs. The gas temperature increases monotonically from 823 to 1315 K, which is mainly determined by the solid temperature, whose variations with time are limited within 20 K. The overall energy in the solid phase is balanced between the reaction heat release, conduction, and convective cooling. In the sensitivity analysis, important input parameters are identified and varied around their base-case values. The resulting changes in the model-predicted performance revealed that the most important parameters are the reduction kinetics, the operating pressure, and the feed stream temperatures. © 2012 American Chemical Society.
Mindfulness-based cognitive therapy for multiple chemical sensitivity: a study protocol for a randomized controlled trial
Hauge Christian Riise
Full Text Available Abstract Background Multiple chemical sensitivity (MCS is a condition characterized by recurrent, self-reported symptoms from multiple organ systems, attributable to exposure to a wide range of chemically unrelated substances at low levels. The pathophysiology is unknown, and affected individuals generally favor avoidance of the symptom triggering substances as a coping strategy. The impact of MCS on daily life may thus be severe. An intervention that may effectively reduce the impact of MCS, alleviate the symptoms and the psychological distress associated with the condition is therefore highly needed. In this study we will assess the effects of a mindfulness-based cognitive (MBCT program on MCS. Methods/Design Using a randomized controlled design (RCT, we will compare MBCT with treatment as usual (TAU. The MBCT intervention will include 8 weekly 2.5 hour sessions, and 45 minutes of mindfulness home practice 6 days each week. Participants will be asked to complete questionnaires at baseline, post-treatment, and at 6 and 12 months' follow-up. Based on sample size estimation, 82 participants will be randomized to either the MBCT intervention or to TAU. The primary outcome will be a measure of the impact of MCS on the participants' lives. The secondary outcome measures are physical symptoms of psychological distress, perceived stress, illness perceptions, QOL, and work ability. Lastly, we will assess whether any effect of MBCT on the primary effect measure is mediated by level of mindfulness, self-compassion, perceived stress, and rumination. Discussion This trial will provide important information on the effects of MBCT on MCS. Trials registration Clinical trials identifier NCT01240395
Bidirectional shifts of TRPM8 channel gating by temperature and chemical agents modulate the cold sensitivity of mammalian thermoreceptors.
Mälkiä, Annika; Madrid, Rodolfo; Meseguer, Victor; de la Peña, Elvira; Valero, María; Belmonte, Carlos; Viana, Félix
TRPM8, a member of the melastatin subfamily of transient receptor potential (TRP) cation channels, is activated by voltage, low temperatures and cooling compounds. These properties and its restricted expression to small sensory neurons have made it the ion channel with the most advocated role in cold transduction. Recent work suggests that activation of TRPM8 by cold and menthol takes place through shifts in its voltage-activation curve, which cause the channel to open at physiological membrane potentials. By contrast, little is known about the actions of inhibitors on the function of TRPM8. We investigated the chemical and thermal modulation of TRPM8 in transfected HEK293 cells and in cold-sensitive primary sensory neurons. We show that cold-evoked TRPM8 responses are effectively suppressed by inhibitor compounds SKF96365, 4-(3-chloro-pyridin-2-yl)-piperazine-1-carboxylic acid (4-tert-butyl-phenyl)-amide (BCTC) and 1,10-phenanthroline. These antagonists exert their effect by shifting the voltage dependence of TRPM8 activation towards more positive potentials. An opposite shift towards more negative potentials is achieved by the agonist menthol. Functionally, the bidirectional shift in channel gating translates into a change in the apparent temperature threshold of TRPM8-expressing cells. Accordingly, in the presence of the antagonist compounds, the apparent response-threshold temperature of TRPM8 is displaced towards colder temperatures, whereas menthol sensitizes the response, shifting the threshold in the opposite direction. Co-application of agonists and antagonists produces predictable cancellation of these effects, suggesting the convergence on a common molecular process. The potential for half maximal activation of TRPM8 activation by cold was approximately 140 mV more negative in native channels compared to recombinant channels, with a much higher open probability at negative membrane potentials in the former. In functional terms, this difference translates
New non-chemically amplified molecular resist design with switchable sensitivity for multi-lithography applications and nanopatterning
Thakur, Neha; Guruprasad Reddy, Pulikanti; Nandi, Santu; Yogesh, Midathala; Sharma, Satinder K.; Pradeep, Chullikkattil P.; Ghosh, Subrata; Gonsalves, Kenneth E.
The development of new photoresist materials for multi-lithography applications is crucial but a challenging task for semiconductor industries. During the last few decades, given the need for new resists to meet the requirements of semiconductor industries, several research groups have developed different resist materials for specific lithography applications. In this context, we have successfully synthesized a new molecular non-chemically amplified resist (n-CAR) (C3) based on the functionalization of aromatic hydroxyl core (4,4‧-(9H-fluorene-9,9-diyl)diphenol) with radiation sensitive sulfonium triflates for various lithography applications. While, micron scale features have been developed using i-line (365 nm) and DUVL (254 nm) exposure tools, electron beam studies on C3 thin films enabled us to pattern 20 nm line features with L/3S (line/space) characteristics on the silicon substrate. The sensitivity and contrast were calculated from the contrast curve analysis as 280 µC cm-2 and 0.025 respectively. Being an important parameter for any newly developed resists, the line edge roughness (LER) of 30 nm (L/5S) features were calculated, using SUMMIT metrology package, to be 3.66  ±  0.3 nm and found to be within the acceptable range. AFM analysis further confirmed 20 nm line width with smooth pattern wall. No deformation of patterned features was observed during AFM analysis which indicated good adhesion property between patterned resists and silicon substrates.
Comparison of Chemical Sensitivity of Fresh and Long-Stored Heat Resistant Neosartorya fischeri Environmental Isolates Using BIOLOG Phenotype MicroArray System.
Jacek Panek
Full Text Available Spoilage of heat processed food and beverage by heat resistant fungi (HRF is a major problem for food industry in many countries. Neosartorya fischeri is the leading source of spoilage in thermally processed products. Its resistance to heat processing and toxigenicity makes studies about Neosartorya fischeri metabolism and chemical sensitivity essential. In this study chemical sensitivity of two environmental Neosartorya fischeri isolates were compared. One was isolated from canned apples in 1923 (DSM3700, the other from thermal processed strawberry product in 2012 (KC179765, used as long-stored and fresh isolate, respectively. The study was conducted using Biolog Phenotype MicroArray platforms of chemical sensitivity panel and traditional hole-plate method. The study allowed for obtaining data about Neosartorya fischeri growth inhibitors. The fresh isolate appeared to be much more resistant to chemical agents than the long-stored isolate. Based on phenotype microarray assay nitrogen compounds, toxic cations and membrane function compounds were the most effective in growth inhibition of N. fischeri isolates. According to the study zaragozic acid A, thallium(I acetate and sodium selenate were potent and promising N. fischeri oriented fungicides which was confirmed by both chemical sensitivity microplates panel and traditional hole-plate methods.
Fragrance allergic contact dermatitis.
Cheng, Judy; Zug, Kathryn A
Fragrances are a common cause of allergic contact dermatitis in Europe and in North America. They can affect individuals at any age and elicit a spectrum of reactions from contact urticaria to systemic contact dermatitis. Growing recognition of the widespread use of fragrances in modern society has fueled attempts to prevent sensitization through improved allergen identification, labeling, and consumer education. This review provides an overview and update on fragrance allergy. Part 1 discusses the epidemiology and evaluation of suspected fragrance allergy. Part 2 reviews screening methods, emerging fragrance allergens, and management of patients with fragrance contact allergy. This review concludes by examining recent legislation on fragrances and suggesting potential additions to screening series to help prevent and detect fragrance allergy.
Cortical activity during olfactory stimulation in multiple chemical sensitivity: a 18F-FDG PET/CT study
Chiaravalloti, Agostino; Di Pietro, Barbara; Pagani, Marco; Micarelli, Alessandro; Alessandrini, Marco; Genovesi, Giuseppe; Schillaci, Orazio
To investigate the differences in brain glucose consumption during olfactory stimulation between subjects affected by multiple chemical sensitivity (MCS) and a group of healthy individuals. Two 18 F-FDG PET/CT scans were performed in 26 subjects (6 men and 20 women; mean age 46.7 ± 11 years) with a clinical diagnosis of MCS and in 11 healthy controls (6 women and 5 men; mean age 45.7 ± 11 years), the first scan after a neutral olfactory stimulation (NS) and the second after a pure olfactory stimulation (OS). Differences in 18 F-FDG uptake were analysed by statistical parametric mapping (SPM2). In controls OS led to an increase in glucose consumption in BA 18 and 19 and a reduction in glucose metabolism in BA 10, 11, 32 and 47. In MCS subjects, OS led to an increase in glucose consumption in BA 20, 23, 18 and 37 and a reduction in glucose metabolism in BA 8, 9 and 10. The results of our study suggest that cortical activity in subjects with MCS differs from that in healthy individuals during olfactory stimulation. (orig.)
Cortical activity during olfactory stimulation in multiple chemical sensitivity: a {sup 18}F-FDG PET/CT study
Chiaravalloti, Agostino; Di Pietro, Barbara [University Tor Vergata, Department of Biomedicine and Prevention, Rome (Italy); Pagani, Marco [Institute of Cognitive Sciences and Technologies, CNR, Rome (Italy); Department of Nuclear Medicine Karolinska Hospital Stockholm, Stockholm (Sweden); Micarelli, Alessandro; Alessandrini, Marco [University Tor Vergata, Department of Medical Science and Translational Medicine, Rome (Italy); Genovesi, Giuseppe [University La Sapienza, Department of Experimental Medicine, Rome (Italy); University La Sapienza, Regional Center for Diagnosis, Treatment and Prevention of MCS, Rome (Italy); Schillaci, Orazio [University Tor Vergata, Department of Biomedicine and Prevention, Rome (Italy); IRCCS Neuromed, Pozzilli (Italy)
To investigate the differences in brain glucose consumption during olfactory stimulation between subjects affected by multiple chemical sensitivity (MCS) and a group of healthy individuals. Two {sup 18}F-FDG PET/CT scans were performed in 26 subjects (6 men and 20 women; mean age 46.7 ± 11 years) with a clinical diagnosis of MCS and in 11 healthy controls (6 women and 5 men; mean age 45.7 ± 11 years), the first scan after a neutral olfactory stimulation (NS) and the second after a pure olfactory stimulation (OS). Differences in {sup 18}F-FDG uptake were analysed by statistical parametric mapping (SPM2). In controls OS led to an increase in glucose consumption in BA 18 and 19 and a reduction in glucose metabolism in BA 10, 11, 32 and 47. In MCS subjects, OS led to an increase in glucose consumption in BA 20, 23, 18 and 37 and a reduction in glucose metabolism in BA 8, 9 and 10. The results of our study suggest that cortical activity in subjects with MCS differs from that in healthy individuals during olfactory stimulation. (orig.)
Cortical activity during olfactory stimulation in multiple chemical sensitivity: a (18)F-FDG PET/CT study.
Chiaravalloti, Agostino; Pagani, Marco; Micarelli, Alessandro; Di Pietro, Barbara; Genovesi, Giuseppe; Alessandrini, Marco; Schillaci, Orazio
To investigate the differences in brain glucose consumption during olfactory stimulation between subjects affected by multiple chemical sensitivity (MCS) and a group of healthy individuals. Two (18)F-FDG PET/CT scans were performed in 26 subjects (6 men and 20 women; mean age 46.7 ± 11 years) with a clinical diagnosis of MCS and in 11 healthy controls (6 women and 5 men; mean age 45.7 ± 11 years), the first scan after a neutral olfactory stimulation (NS) and the second after a pure olfactory stimulation (OS). Differences in (18)F-FDG uptake were analysed by statistical parametric mapping (SPM2). In controls OS led to an increase in glucose consumption in BA 18 and 19 and a reduction in glucose metabolism in BA 10, 11, 32 and 47. In MCS subjects, OS led to an increase in glucose consumption in BA 20, 23, 18 and 37 and a reduction in glucose metabolism in BA 8, 9 and 10. The results of our study suggest that cortical activity in subjects with MCS differs from that in healthy individuals during olfactory stimulation.
Further important sensitizers in patients sensitive to fragrances
Frosch, Peter J; Johansen, J D; Menné, T
(series I). Each patient was classified regarding a history of adverse reactions to fragrances: certain, probable, questionable, none. Reactions to FM occurred in 11.3% of the subjects. The 6 substances with the highest reactivity following FM were Lyral (2.7%), citral (1.1%), farnesol P (0...... further sensitizers relevant for patch testing of patients with contact dermatitis, of which Lyral is the most important single chemical....
Heterodimerization with the β1 subunit directs the α2 subunit of nitric oxide-sensitive guanylyl cyclase to calcium-insensitive cell-cell contacts in HEK293 cells: Interaction with Lin7a.
Hochheiser, Julia; Haase, Tobias; Busker, Mareike; Sömmer, Anne; Kreienkamp, Hans-Jürgen; Behrends, Sönke
Nitric oxide-sensitive guanylyl cyclase is a heterodimeric enzyme consisting of an α and a β subunit. Two different α subunits (α 1 and α 2 ) give rise to two heterodimeric enzymes α 1 /β 1 and α 2 /β 1 . Both coexist in a wide range of tissues including blood vessels and the lung, but expression of the α 2 /β 1 form is generally much lower and approaches levels similar to the α 1 /β 1 form in the brain only. In the present paper, we show that the α 2 /β 1 form interacts with Lin7a in mouse brain synaptosomes based on co-precipitation analysis. In HEK293 cells, we found that the overexpressed α 2 /β 1 form, but not the α 1 /β 1 form is directed to calcium-insensitive cell-cell contacts. The isolated PDZ binding motif of an amino-terminally truncated α 2 subunit was sufficient for cell-cell contact localization. For the full length α 2 subunit with the PDZ binding motif this was only the case in the heterodimer configuration with the β 1 subunit, but not as isolated α 2 subunit. We conclude that the PDZ binding motif of the α 2 subunit is only accessible in the heterodimer conformation of the mature nitric oxide-sensitive enzyme. Interaction with Lin7a, a small scaffold protein important for synaptic function and cell polarity, can direct this complex to nectin based cell-cell contacts via MPP3 in HEK293 cells. We conclude that heterodimerization is a prerequisite for further protein-protein interactions that direct the α 2 /β 1 form to strategic sites of the cell membrane with adjacent neighbouring cells. Drugs increasing the nitric oxide-sensitivity of this specific form may be particularly effective. Copyright © 2016 Elsevier Inc. All rights reserved.
Contact sensitization to 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (MCI/MI). A European multicentre study
Menné, T; Frosch, P J; Veien, Niels
, formaldehyde, paraben-mix, and MCI/MI. 19.4% of the patients had positive patch tests to nickel, making this the most common allergen. 3% of the patients reacted to 100 ppm MCI/MI, while 2.6% reacted to formaldehyde and 1.1% to parabens. There was great variation in the frequency of MCI/MI sensitivity among...
A simple sheathless CE-MS interface with a sub-micrometer electrical contact fracture for sensitive analysis of peptide and protein samples
Nguyen, Tam T. T. N.; Petersen, Nickolaj J.; Rand, Kasper Dyrberg
Online coupling of capillary electrophoresis (CE) to electrospray ionization mass spectrometry (MS) has shown considerable potential, however, technical challenges have limited its use. In this study, we have developed a simple and sensitive sheathless CE-MS interface based on the novel concept o...
Contact sensitization to calocephalin, a sesquiterpene lactone of the guaianolide type from cushion bush (Leucophyta brownii, Compositae)
Paulsen, Evy; Christensen, Lars P; Hindsén, Monica
Cushion bush [Leucophyta brownii Cass. = Calocephalus brownii (Cass.) F. Muell.] is an Australian Compositae shrub that has been introduced into Scandinavia as a pot plant. The first case of sensitization occurred in a gardener, and the main allergen was identified as the guaianolide calocephalin....
Aquatic plants: Test species sensitivity and minimum data requirement evaluations for chemical risk assessments and aquatic life criteria development for the USA
Phytotoxicity results from the publicly-available ECOTOX database were summarized for 20 chemicals and 188 aquatic plants to determine species sensitivities and the ability of a species-limited toxicity data set to serve as a surrogate for a larger data set. The lowest effect con...
LSENS: A General Chemical Kinetics and Sensitivity Analysis Code for homogeneous gas-phase reactions. Part 1: Theory and numerical solution procedures
Radhakrishnan, Krishnan
LSENS, the Lewis General Chemical Kinetics and Sensitivity Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 1 of a series of three reference publications that describe LENS, provide a detailed guide to its usage, and present many example problems. Part 1 derives the governing equations and describes the numerical solution procedures for the types of problems that can be solved. The accuracy and efficiency of LSENS are examined by means of various test problems, and comparisons with other methods and codes are presented. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions.
Cobalt as chemical modifier to improve chromium sensitivity and minimize matrix effects in tungsten coil atomic emission spectrometry
Silva, Sidnei G. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Donati, George L., E-mail: georgedonati@yahoo.com.br [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Santos, Luana N. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Jones, Bradley T. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Nóbrega, Joaquim A. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil)
Graphical abstract: -- Highlights: •Charge transfer reactions increase the population of Cr{sup +}. •Chromium ions and electrons recombine to form excited-state Cr atoms. •A 10-fold improvement in LOD is observed for Cr emission measurements. •The two-step ionization/excitation mechanism improves sensitivity and accuracy. •High concentrations of Co also minimize matrix effects. -- Abstract: Cobalt is used as chemical modifier to improve sensitivity and minimize matrix effects in Cr determinations by tungsten coil atomic emission spectrometry (WCAES). The atomizer is a tungsten filament extracted from microscope light bulbs. A solid-state power supply and a handheld CCD-based spectrometer are also used in the instrumental setup. In the presence of 1000 mg L{sup −1} Co, WCAES limit of detection for Cr (λ = 425.4 nm) is calculated as 0.070 mg L{sup −1}; a 10-fold improvement compared to determinations without Co modifier. The mechanism involved in such signal enhancement is similar to the one observed in ICP OES and ICP-MS determinations of As and Se in the presence of C. Cobalt increases the population of Cr{sup +} by charge transfer reactions. In a second step, Cr{sup +}/e{sup −} recombination takes place, which results in a larger population of excited-state Cr atoms. This alternative excitation route is energetically more efficient than heat transfer from atomizer and gas phase to analyte atoms. A linear dynamic range of 0.25–10 mg L{sup −1} and repeatability of 3.8% (RSD, n = 10) for a 2.0 mg L{sup −1} Cr solution are obtained with this strategy. The modifier high concentration also contributes to improving accuracy due to a matrix-matching effect. The method was applied to a certified reference material of Dogfish Muscle (DORM-2) and no statistically significant difference was observed between determined and certified Cr values at a 95% confidence level. Spike experiments with bottled water samples resulted in recoveries between 93% and
Self-testing for contact sensitization to hair dyes--scientific considerations and clinical concerns of an industry-led screening programme
Thyssen, Jacob P; Søsted, Heidi; Uter, Wolfgang
The cosmetic industry producing hair dyes has, for many years, recommended that their consumers perform 'a hair dye allergy self-test' or similar prior to hair dyeing, to identify individuals who are likely to react upon subsequent hair dyeing. This review offers important information...... on the requirements for correct validation of screening tests, and concludes that, in its present form, the hair dye self-test has severe limitations: (i) it is not a screening test but a diagnostic test; (ii) it has not been validated according to basic criteria defined by scientists; (iii) it has been evaluated...... in the wrong population group; (iv) skin reactions have been read by dermatologists and not by the targeted group (consumers and hairdressers); (v) hair dyes contain strong and extreme sensitizers that are left on the skin in high concentrations, potentially resulting in active sensitization; and (vi...
Lettuce contact allergy.
Paulsen, Evy; Andersen, Klaus E
Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Advantages of Chemical Exchange-Sensitive Spin-Lock (CESL) Over Saturation Transfer (CEST) for Hydroxyl- and Amine-Water Proton Exchange Studies
The chemical exchange (CE) rate of endogenous hydroxyl and amine protons with water is often comparable to the difference in their chemical shifts. These intermediate exchange (IMEX) processes have been imaged by the CE saturation transfer (CEST) approach with low-power and long-duration irradiation. However, its sensitivity is not optimal, and more importantly, the signal is contaminated by slow magnetization transfer processes. Here, the property of CEST signals is compared to a CE-sensitive spin-locking (CESL) technique irradiating at the labile proton frequency. Firstly, using a higher power and shorter irradiation in CE-MRI yields i) increasing selectivity to faster chemical exchange rates by higher sensitivity to faster exchanges and less sensitivity to slower CE and magnetization transfer processes, and ii) decreasing in vivo asymmetric magnetization transfer contrast measured at ±15 ppm. The sensitivity gain of CESL over CEST is higher for a higher-power and shorter irradiation. Unlike CESL, CEST signals oscillate at a very high power and short irradiation. Secondly, time-dependent CEST and CESL signals are well modeled by analytical solutions of CE-MRI with asymmetric population approximation (CEAPA), which can be used for quantitative CE-MRI, and validated by simulations of Bloch-McConnell equations and phantom experiments. Lastly, in vivo amine-water proton exchange contrast measured at 2.5 ppm with ω1 of 500 Hz is 18% higher in sensitivity for CESL than CEST at 9.4 T. Overall, CESL provides better exchange rate selectivity and sensitivity than CEST; therefore, CESL is more suitable for CE-MRI of IMEX protons. PMID:25199631
Visible-light sensitization of TiO2 photocatalysts via wet chemical N-doping for the degradation of dissolved organic compounds in wastewater treatment: a review
Zhang, Wei; Jia, Baoping; Wang, Qiuze; Dionysiou, Dionysois
Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO2 photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO2 synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO2 preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO2 in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment.
Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO 2 photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO 2 synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO 2 preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO 2 in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment
Physico-chemical behaviour of a metal/polymer contact subject to a low amplitude friction in a chlorinated medium. Effect of ionitriding and ion implantation surface treatment
Rabbe, L.M.
The fretting-corrosion behaviour of two tribological couples (TA6V/PMMA and 316L/PMMA) had been studied in order to better understand the degradation mechanisms observed on pivot prosthesis sealed in bones. Pressure appears to have a major role; at high contact pressure, the PMMA wear is the main degradation mechanism with PMMA debris acting as a metal surface protecting agent; at low contact pressure, both material deterioration is involved, and titanium has a corrosion-dominated degradation. An optimal resistance to fretting is achieved when TA6V is coated with Ti N (ion implantation) and Ti N, Ti 2 N (ionitriding). When nitriding, processing temperature appears as a critical factor to ensure thickness and homogeneity of the nitride coatings. 181 p., 106 figs., 110 refs
Drug loading optimization and extended drug delivery of corticoids from pHEMA based soft contact lenses hydrogels via chemical and microstructural modifications.
García-Millán, Eva; Koprivnik, Sandra; Otero-Espinar, Francisco Javier
This paper proposes an approach to improve drug loading capacity and release properties of poly(2-hydroxyethyl methacrylate) (p(HEMA)) soft contact lenses based on the optimization of the hydrogel composition and microstructural modifications using water during the polymerization process. P(HEMA) based soft contact lenses were prepared by thermal or photopolymerization of 2-hydroxyethyl methacrylate (HEMA) solutions containing ethylene glycol di-methacrylate as crosslinker and different proportions of N-vinyl-2-pyrrolidone (NVP) or methacrylic acid (MA) as co-monomers. Transmittance, water uptake, swelling, microstructure, drug absorption isotherms and in vitro release were characterized using triamcinolone acetonide (TA) as model drug. Best drug loading ratios were obtained with lenses containing the highest amount (200 mM) of MA. Incorporation of 40% V/V of water during the polymerization increases the hydrogel porosity giving a better drug loading capacity. In vitro TA release kinetics shows that MA hydrogels released the drug significantly faster than NVP-hydrogels. Drug release was found to be diffusion controlled and kinetics was shown to be reproducible after consecutive drug loading/release processes. Results of p(HEMA) based soft contact lenses copolymerized with ethylene glycol dimethacrylate (EGDMA) and different co-monomers could be a good alternative to optimize the loading and ocular drug delivery of this corticosteroid drug. Copyright © 2015. Published by Elsevier B.V.
Old and stable soil organic matter is not necessarily chemically recalcitrant: Implications for modeling concepts and temperature sensitivity
Kleber, M.; Nico, P.S.; Plante, A.; Filley, T.; Kramer, M.; Swanston, C.; Sollins, P.
Soil carbon turnover models generally divide soil carbon into pools with varying intrinsic decomposition rates. Although these decomposition rates are modified by factors such as temperature, texture, and moisture, they are rationalized by assuming chemical structure is a primary controller of decomposition. In the current work, we use near edge X-ray absorption fine structure (NEXAFS) spectroscopy in combination with differential scanning calorimetry (DSC) and alkaline cupric oxide (CuO) oxidation to explore this assumption. Specifically, we examined material from the 2.3-2.6 kg L{sup -1} density fraction of three soils of different type (Oxisol, Alfisol, Inceptisol). The density fraction with the youngest {sup 14}C age (Oxisol, 107 years) showed the highest relative abundance of aromatic groups and the lowest O-alkyl C/aromatic C ratio as determined by NEXAFS. Conversely, the fraction with the oldest C (Inceptisol, 680 years) had the lowest relative abundance of aromatic groups and highest O-alkyl C/aromatic C ratio. This sample also had the highest proportion of thermally labile materials as measured by DSC, and the highest ratio of substituted fatty acids to lignin phenols as indicated by CuO oxidation. Therefore, the organic matter of the Inceptisol sample, with a {sup 14}C age associated with 'passive' pools of carbon (680 years), had the largest proportion of easily metabolizable organic molecules with low thermodynamic stability, whereas the organic matter of the much younger Oxisol sample (107 years) had the highest proportion of supposedly stable organic structures considered more difficult to metabolize. Our results demonstrate that C age is not necessarily related to molecular structure or thermodynamic stability, and we suggest that soil carbon models would benefit from viewing turnover rate as codetermined by the interaction between substrates, microbial actors, and abiotic driving variables. Furthermore, assuming that old carbon is composed
Occupational contact dermatitis in hairdressers
Schwensen, Jakob F; Johansen, Jeanne Duus; Veien, Niels K
BACKGROUND: Occupational contact dermatitis among hairdressers is frequent, owing to daily exposure to irritants and allergens. OBJECTIVES: To identify sensitization to the most common allergens associated with the occupation of hairdressing. METHODS: Patch test results of 399 hairdressers and 1995...... matched controls with contact dermatitis, registered by the Danish Contact Dermatitis Group between January 2002 and December 2011, were analysed. All patients were patch tested with the European baseline series, and hairdressers were additionally tested with the hairdressing series. RESULTS: Occupational...... contact dermatitis (p dermatitis was less commonly observed among hairdressers (21.3%) than among controls (29.4%) (p
Fast, sensitive, and selective gas chromatography tandem mass spectrometry method for the target analysis of chemical secretions from femoral glands in lizards.
Sáiz, Jorge; García-Roa, Roberto; Martín, José; Gómara, Belén
Chemical signaling is a widespread mode of communication among living organisms that is used to establish social organization, territoriality and/or for mate choice. In lizards, femoral and precloacal glands are important sources of chemical signals. These glands protrude chemical secretions used to mark territories and also, to provide valuable information from the bearer to other individuals. Ecologists have studied these chemical secretions for decades in order to increase the knowledge of chemical communication in lizards. Although several studies have focused on the chemical analysis of these secretions, there is a lack of faster, more sensitive and more selective analytical methodologies for their study. In this work a new GC coupled to tandem triple quadrupole MS (GC-QqQ (MS/MS)) methodology is developed and proposed for the target study of 12 relevant compounds often found in lizard secretions (i.e. 1-hexadecanol, palmitic acid, 1-octadecanol, oleic acid, stearic acid, 1-tetracosanol, squalene, cholesta-3,5-diene, α-tocopherol, cholesterol, ergosterol and campesterol). The method baseline-separated the analytes in less than 7min, with instrumental limits of detection ranging from 0.04 to 6.0ng/mL. It was possible to identify differences in the composition of the samples from the lizards analyzed, which depended on the species, the habitat occupied and the diet of the individuals. Moreover, α-tocopherol has been determined for the first time in a lizard species, which was thought to lack its expression in chemical secretions. Globally, the methodology has been proven to be a valuable alternative to other published methods with important improvements in terms of analysis time, sensitivity, and selectivity. Copyright © 2017 Elsevier B.V. All rights reserved.
Precision contact level gauge
Krejci, M.; Pilat, M.; Stulik, P.
Equipment was developed measuring the heavy water level in the TR-0 reactor core within an accuracy of several hundredths of a millimeter in a range of around 3.5 m and at a temperature of up to 90 degC. The equipment uses a vibrating needle contact as a high sensitivity level gauge and a servomechanical system with a motion screw carrying the gauge for monitoring and measuring the level in the desired range. The advantage of the unique level gauge consists in that that the transducer converts the measured level position to an electric signal, ie., pulse width, with high sensitivity and without hysteresis. (Kr)
Fragrance contact allergy
Johansen, Jeanne D
. This gives a positive patch-test reaction in about 10% of tested patients with eczema, and the most recent estimates show that 1.7-4.1% of the general population are sensitized to ingredients of the fragrance mix. Fragrance allergy occurs predominantly in women with facial or hand eczema. These women...... development to identify contact allergy to new allergens, reflecting the continuous developments and trends in exposure....
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 12, Revision 2 (FGE.12Rev2): Primary saturated or unsaturated alicyclic alcohol, aldehyde, acid, and esters from chemical group 7
The European Food Safety Authority (EFSA) asked the Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (the Panel) to provide scientific advice to the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs....... However, this does not preclude evaluation of the flavouring substances in the present group using the Procedure (SCF, 1999a). It is considered that on the basis of the default MSDI approach these nine flavouring substances would not give rise to safety concerns at the estimated levels of intake arising...
Pediatric contact dermatitis
Sharma Vinod
Full Text Available Allergic contact dermatitis (ACD in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and it begins right from early childhood, including 1-week-old neonates. Vaccinations, piercing, topical medicaments and cosmetics in younger patients are potential exposures for sensitization. Nickel is the most common sensitizer in almost all studies pertaining to pediatric contact dermatitis. Other common allergens reported are cobalt, fragrance mix, rubber, lanolin, thiomersol, neomycin, gold, mercapto mix, balsum of Peru and colophony. Different factors like age, sex, atopy, social and cultural practices, habit of parents and caregivers and geographic changes affect the patterns of ACD and their variable clinical presentation. Patch testing should be considered not only in children with lesions of a morphology suggestive of ACD, but in any child with dermatitis that is difficult to control.
Evaluation of the skin sensitization potential of chemicals using expression of co-stimulatory molecules, CD54 and CD86, on the naive THP-1 cell line.
Yoshida, Y; Sakaguchi, H; Ito, Y; Okuda, M; Suzuki, H
It has been known that dendritic cells (DCs) including Langerhans cells (LCs) play a critical role in the skin sensitization process. Many attempts have been made to develop in vitro sensitization tests that employ DCs derived from peripheral blood mononuclear cells (PBMC-DC) or CD34+ hematopoietic progenitor cells (CD34+ HPC) purified from cord blood or bone marrow. However, the use of the DCs in in vitro methods has been difficult due to the nature of these cells such as low levels in the source and/or donor-to-donor variability. In our studies, we employed the human monocytic leukemia cell line, THP-1, in order to avoid some of these difficulties. At the start, we examined whether treatment of the cells with various cytokines could produce DCs from THP-1. Treatment of THP-1 cells with cytokines such as GM-CSF, IL-4, TNF-alpha, and/or PMA did induce some phenotypic changes in THP-1 cells that were characteristic of DCs. Subsequently, responses to a known sensitizer, dinitrochlorobenzene (DNCB), and a non-sensitizer, dimethyl sulfoxide (DMSO) or sodium lauryl sulfate (SLS), on the expression of co-stimulatory molecules, CD54 and CD86, were examined between the naive cells and the cytokine-treated cells. Interestingly, the naive THP-1 cells responded only to DNCB and the response to the sensitizer was more distinct than cytokine-treated THP-1 cells. Similar phenomena were also observed in the human myeloid leukemia cell line, KG-1. Furthermore, with treatment of DNCB, naive THP-1 cells showed augmented expression of HLA, CD80 and secretion of IL-1 beta. The response of THP-1 cells to a sensitizer was similar to that of LCs/DCs. Upon demonstrating the differentiation of monocyte cells in our system, we then evaluated a series of chemicals, including known sensitizers and non-sensitizers, for their potential to augment CD54 and CD86 expression on naive THP-1 cells. Indeed, known sensitizers such as PPD and 2-MBT significantly augmented CD54 and CD86 expression in a
The sensitivity and reproducibility of the zebrafish (Danio rerio) embryo test for the screening of waste water quality and for testing the toxicity of chemicals.
Lahnsteiner, Franz
The sensitivity of the zebrafish embryo test, a test proposed for routine waste water control, was compared with the acute fish toxicity test, in the determination of six types of waste water and ten different chemicals. The waste water was sampled from the following industrial processes: paper and cardboard production, hide tanning, metal galvanisation, carcass treatment and utilisation, and sewage treatment. The chemicals tested were: dimethylacetamide, dimethylsulphoxide, cadmium chloride, cyclohexane, hydroquinone, mercuric chloride, nickel chloride, nonylphenol, resmethrin and sodium nitrite. For many of the test substances, the zebrafish embryo test and the acute fish toxicity test results showed high correlations. However, there were certain environmentally-relevant substances for which the results of the zebrafish embryo test and the acute fish toxicity test differed significantly, up to 10,000-fold (Hg(2+) > 150-fold difference; NO(2)(-) > 300-fold; Cd(2+) > 200-fold; resmethrin > 10,000-fold). For the investigated waste water samples and chemicals, the survival rate of the zebrafish embryos showed high variations between different egg samples, within the range of the EC50 concentration. Subsequently, 5-6 parallel assays were deemed to be the appropriate number necessary for the precise evaluation of the toxicity of the test substances. Also, it was found that the sensitivities of different ontogenetic stages to chemical exposure differed greatly. During the first 12 hours after fertilisation (4-cell stage to the 5-somite stage), the embryos reacted most sensitively to test substance exposure, whereas the later ontogenetic stages showed only slight or no response, indicating that the test is most sensitive during the first 24 hours post-fertilisation.
EFSA EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 304 (FGE.304): Five carboxamides from chemical group 30
The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate five flavouring substances in the Flavouring Group Evaluation 304, using the Procedure in Commission Regulation (EC) No 1565/2000. None of the substances...... data are required. Besides the safety assessment of these flavouring substances, the specifications for the materials of commerce have also been considered. Specifications including complete purity criteria and identity for the materials of commerce have been provided for all five candidate substances....
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF) ; Scientific Opinion on Flavouring Group Evaluation 305 (FGE.305): L - Methionylglycine of chemical group 34
Beltoft, Vibe Meister; Binderup, Mona-Lise; Frandsen, Henrik Lauritz
use in foods that are not heated or intended to be heated. Besides the safety assessment of the flavouring substance, the specifications for the material of commerce have also been considered. Adequate specifications including complete purity criteria and identity for the material of commerce have......The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate one flavouring substance, the dipeptide L-methionylglycine [FL-no: 17.037], in the Flavouring Group Evaluation 305, using the Procedure in Commission...... been provided for the candidate substance. © European Food Safety Authority, 2013...
Study on the chemical stability of catalyst counter electrodes for dye-sensitized solar cells using a simple X-ray photoelectron spectroscopy-based method
Yun, Dong-Jin; Kim, Jungmin; Chung, Jongwon; Park, SungHoon; Baek, WoonJoong; Kim, Yongsu; Kim, Seongheon; Kwon, Young-Nam; Chung, JaeGwan; Kyoung, Yongkoo; Kim, Ki-Hong; Heo, Sung
Since the chemical/electrical stability and catalytic activity are essential conditions for catalyst counter electrodes (CCEs) in dye-sensitized solar cells (DSSCs), a simple dipping method is employed for evaluating the chemical stability of CCE candidates in an iodine-based liquid electrolyte (I-electrolyte). The chemical stabilities and transition mechanisms of the CCEs are successfully analyzed by studying the chemical transitions in X-ray photoelectron spectroscopy (XPS) core levels after dipping in the I-electrolyte. All films including the Pt film undergo degradation depending on the type of material. While dipping in the I-electrolyte, Cu and Au films scarcely dissolves as their respective metal sulfides, and the Al film gradually loss its metallic properties owing to Al2O3 growth. On the other hand, a previously unknown transition mechanism of organic conducting CCEs is determined based on the proposed method. Compared to the other metal films, the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and multi wall carbon nanotube (MWCNT)/PEDOT:PSS films undergo an entirely unique transition mechanism, which results from the chemical adsorption of organic molecules onto PEDOT:PSS molecules in the I-electrolyte. Consequently, these chemical structure transitions correspond well to the degrees of alternation in the electrical properties of DSSCs with all the investigated CCEs.
Trace level detection of compounds related to the chemical weapons convention by 1H-detected 13C NMR spectroscopy executed with a sensitivity-enhanced, cryogenic probehead.
Cullinan, David B; Hondrogiannis, George; Henderson, Terry J
Two-dimensional 1H-13C HSQC (heteronuclear single quantum correlation) and fast-HMQC (heteronuclear multiple quantum correlation) pulse sequences were implemented using a sensitivity-enhanced, cryogenic probehead for detecting compounds relevant to the Chemical Weapons Convention present in complex mixtures. The resulting methods demonstrated exceptional sensitivity for detecting the analytes at trace level concentrations. 1H-13C correlations of target analytes at chemical shift information could be derived quickly and simultaneously from the resulting spectra. The fast-HMQC pulse sequences generated magnitude mode spectra suitable for detailed analysis in approximately 4.5 h and can be used in experiments to efficiently screen a large number of samples. The HSQC pulse sequences, on the other hand, required roughly twice the data acquisition time to produce suitable spectra. These spectra, however, were phase-sensitive, contained considerably more resolution in both dimensions, and proved to be superior for detecting analyte 1H-13C correlations. Furthermore, a HSQC spectrum collected with a multiplicity-edited pulse sequence provided additional structural information valuable for identifying target analytes. The HSQC pulse sequences are ideal for collecting high-quality data sets with overnight acquisitions and logically follow the use of fast-HMQC pulse sequences to rapidly screen samples for potential target analytes. Use of the pulse sequences considerably improves the performance of NMR spectroscopy as a complimentary technique for the screening, identification, and validation of chemical warfare agents and other small-molecule analytes present in complex mixtures and environmental samples.
Analysis of air-, moisture- and solvent-sensitive chemical compounds by mass spectrometry using an inert atmospheric pressure solids analysis probe.
Mosely, Jackie A; Stokes, Peter; Parker, David; Dyer, Philip W; Messinis, Antonis M
A novel method has been developed that enables chemical compounds to be transferred from an inert atmosphere glove box and into the atmospheric pressure ion source of a mass spectrometer whilst retaining a controlled chemical environment. This innovative method is simple and cheap to implement on some commercially available mass spectrometers. We have termed this approach inert atmospheric pressure solids analysis probe ( iASAP) and demonstrate the benefit of this methodology for two air-/moisture-sensitive chemical compounds whose characterisation by mass spectrometry is now possible and easily achieved. The simplicity of the design means that moving between iASAP and standard ASAP is straightforward and quick, providing a highly flexible platform with rapid sample turnaround.
HTTK R Package v1.5 - Identifying populations sensitive to environmental chemicals by simulating toxicokinetic variability
Data.gov (United States)
U.S. Environmental Protection Agency — httk: High-Throughput Toxicokinetics Functions and data tables for simulation and statistical analysis of chemical toxicokinetics ("TK") using data obtained from...
Contact activation of blood-plasma coagulation
Golas, Avantika
Surface engineering of biomaterials with improved hemocompatibility is an imperative, given the widespread global need for cardiovascular devices. Research summarized in this dissertation focuses on contact activation of FXII in buffer and blood plasma frequently referred to as autoactivation. The extant theory of contact activation imparts FXII autoactivation ability to negatively charged, hydrophilic surfaces. According to this theory, contact activation of plasma involves assembly of proteins comprising an "activation complex" on activating surfaces mediated by specific chemical interactions between complex proteins and the surface. This work has made key discoveries that significantly improve our core understanding of contact activation and unravel the existing paradigm of plasma coagulation. It is shown herein that contact activation of blood factor XII (FXII, Hageman factor) in neat-buffer solution exhibits a parabolic profile when scaled as a function of silanized-glass-particle activator surface energy (measured as advancing water adhesion tension t°a=g° Iv costheta in dyne/cm, where g°Iv is water interfacial tension in dyne/cm and theta is the advancing contact angle). Nearly equal activation is observed at the extremes of activator water-wetting properties --36 moderated by adsorption of plasma proteins unrelated to coagulation through an "adsorption-dilution" effect that blocks FXII contact with hydrophobic activator surfaces. The adsorption-dilution effect explains the apparent specificity for hydrophilic activators pursued by earlier investigators. Finally a comparison of FXII autoactivation in buffer, serum, protein cocktail, and plasma solutions is shown herein. Activation of blood plasma coagulation in vitro by contact with material surfaces is demonstrably dependent on plasma-volume-to-activator-surface-area ratio. However, activation of factor XII dissolved in buffer, protein cocktail, heat-denatured serum, and FXI deficient plasma does not
Prioritized Contact Transport Stream
Hunt, Walter Lee, Jr. (Inventor)
A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.
Friction behavior of glass and metals in contact with glass in various environments
Buckley, D. H.
Sliding friction experiments have been conducted for heat-resistant glass and metals in contact with glass. These experiments were conducted in various environments including vacuum, moist air, dry air, octane, and stearic acid in hexadecane. Glass exhibited a higher friction force in moist air than it did in vacuum when in sliding contact with itself. The metals, aluminum, iron, and gold, all exhibited the same friction coefficient when sliding on glass in vacuum as glass sliding on glass. Gold-to-glass contacts were extremely sensitive to the environment despite the relative chemical inertness of gold.
Unexpected Ge-Ge contacts in the two-dimensional Ge{sub 4}Se{sub 3}Te phase and analysis of their chemical cause with the density of energy (DOE) function
Kuepers, Michael; Konze, Philipp M.; Maintz, Stefan; Steinberg, Simon [Institute of Inorganic Chemistry, Chair of Solid-State and Quantum Chemistry, RWTH Aachen University (Germany); Mio, Antonio M.; Cojocaru-Miredin, Oana; Zhu, Min; Wuttig, Matthias [I. Physikalisches Institut, RWTH Aachen University (Germany); Mueller, Merlin; Mayer, Joachim [Gemeinschaftslabor fuer Elektronenmikroskopie, RWTH Aachen University (Germany); Luysberg, Martina [Ernst-Ruska-Center, Forschungszentrum Juelich GmbH (Germany); Dronskowski, Richard [Institute of Inorganic Chemistry, Chair of Solid-State and Quantum Chemistry, RWTH Aachen University (Germany); Juelich-Aachen Research Alliance (JARA-HPC), RWTH Aachen University (Germany)
A hexagonal phase in the ternary Ge-Se-Te system with an approximate composition of GeSe{sub 0.75}Te{sub 0.25} has been known since the 1960s but its structure has remained unknown. We have succeeded in growing single crystals by chemical transport as a prerequisite to solve and refine the Ge{sub 4}Se{sub 3}Te structure. It consists of layers that are held together by van der Waals type weak chalcogenide-chalcogenide interactions but also display unexpected Ge-Ge contacts, as confirmed by electron microscopy analysis. The nature of the electronic structure of Ge{sub 4}Se{sub 3}Te was characterized by chemical bonding analysis, in particular by the newly introduced density of energy (DOE) function. The Ge-Ge bonding interactions serve to hold electrons that would otherwise go into antibonding Ge-Te contacts. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 310 (FGE.310): Rebaudioside A from chemical group 30
The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate rebaudioside A [FL-no: 16.113], a steviol glycoside. The substance was not considered to have genotoxic potential. Since a comprehensive and adequate...... toxicological database, including human studies, is available for steviol glycosides, the Panel based its evaluation of rebaudioside A on a comparison of the ADI of 4 mg/kg bw, expressed as steviol, established by EFSA, with the estimated dietary exposure figures based on the MSDI and mTAMDI approaches....... The Panel concluded that rebaudioside A [FL-no: 16.113] would not give rise to safety concerns at the estimated level of intake arising from its use as flavouring substance....
Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact.
Zeng, Hao; Takahashi, Tsunaki; Kanai, Masaki; Zhang, Guozhu; He, Yong; Nagashima, Kazuki; Yanagida, Takeshi
Long-term stability of a chemical sensor is an essential quality for long-term collection of data related to exhaled breath, environmental air, and other sources in the Internet of things (IoT) era. Although an oxide nanowire sensor has shown great potential as a chemical sensor, the long-term stability of sensitivity has not been realized yet due to electrical degradation under harsh sensing conditions. Here, we report a rational concept to accomplish long-term electrical stability of metal oxide nanowire sensors via introduction of a heavily doped metal oxide contact layer. Antimony-doped SnO 2 (ATO) contacts on SnO 2 nanowires show much more stable and lower electrical contact resistance than conventional Ti contacts for high temperature (200 °C) conditions, which are required to operate chemical sensors. The stable and low contact resistance of ATO was confirmed for at least 1960 h under 200 °C in open air. This heavily doped oxide contact enables us to realize the long-term stability of SnO 2 nanowire sensors while maintaining the sensitivity for both NO 2 gas and light (photo) detections. The applicability of our method is confirmed for sensors on a flexible polyethylene naphthalate (PEN) substrate. Since the proposed fundamental concept can be applied to various oxide nanostructures, it will give a foundation for designing long-term stable oxide nanomaterial-based IoT sensors.
The influence of hard-baking temperature applied for SU8 sensor layer on the sensitivity of capacitive chemical sensor
Klanjšek Gunde, Marta; Hauptman, Nina; Ma�ek, Marijan; Kunaver, Matjaž
SU8, the near-UV photosensitive epoxy-based polymer was used as a sensor layer in the capacitive chemical sensor, ready for integration with a generic double-metal CMOS technology. It was observed that the response of the sensor slowly increases with the temperature applied in hard-baking process as long as it remains below 300°C. At this temperature the response of the sensor abruptly increases and becomes almost threefold. It was shown that fully crosslinked structure of the sensor layer becomes opened and disordered when the sensor is hard-baked at temperatures between 300°C and 320°C, that is, still well below the degradation temperature of the polymer. These changes in chemical structure were analyzed by Fourier-transform infrared spectroscopy. The temperature-dependent changes of the sensor layer structure enable one to prepare a combination of capacitive chemical sensors with good discrimination between some volatile organic compounds.
Influence of the physical–chemical properties of polyaniline thin films on the final sensitivity of varied field effect sensors
Mello, Hugo José Nogueira Pedroza Dias; Heimfarth, Tobias; Mulato, Marcelo
We investigated the use of electrodeposited polyaniline (PANI) thin sensing films in pH sensors. Two configurations of the Extended Gate Field Effect Transistor (EGFET) sensor were studied: the Single EGFET (S-EGFET) and the Instrumental Amplifier EGFET (IA-EGFET) setups. The films were analyzed in both systems and the sensitivity and linearity of each sensor were compared. Initial sensitivities (70–80 mV/pH) measured in the IA-EGFET were reduced due to polymer bulk protonation after a prior measurement in the S-EGFET system. Films with high amount of deposited polymer had their sensitivities least reduced. Bulk protonation occurred due to the step potential applied to the reference electrode in the S-EGFET system. These changes were also analyzed by scanning electron microscopy (SEM), visible reflectance spectroscopy and evaluation of CIE L*a*b* color scale. PANI pH EGFET sensors exhibited good linearity and stability that along with their high sensitivity, easy processing and low cost film production have large potential applications. - Highlights: • Electrodeposited polyaniline thin films were analyzed in two EGFET setups. • Polymer protonation provided changeable sensitivities. • Color and morphological variation confirm polymer aggregation and electrical changes
Mello, Hugo José Nogueira Pedroza Dias, E-mail: hugodiasmello@usp.br; Heimfarth, Tobias; Mulato, Marcelo
We investigated the use of electrodeposited polyaniline (PANI) thin sensing films in pH sensors. Two configurations of the Extended Gate Field Effect Transistor (EGFET) sensor were studied: the Single EGFET (S-EGFET) and the Instrumental Amplifier EGFET (IA-EGFET) setups. The films were analyzed in both systems and the sensitivity and linearity of each sensor were compared. Initial sensitivities (70–80 mV/pH) measured in the IA-EGFET were reduced due to polymer bulk protonation after a prior measurement in the S-EGFET system. Films with high amount of deposited polymer had their sensitivities least reduced. Bulk protonation occurred due to the step potential applied to the reference electrode in the S-EGFET system. These changes were also analyzed by scanning electron microscopy (SEM), visible reflectance spectroscopy and evaluation of CIE L*a*b* color scale. PANI pH EGFET sensors exhibited good linearity and stability that along with their high sensitivity, easy processing and low cost film production have large potential applications. - Highlights: • Electrodeposited polyaniline thin films were analyzed in two EGFET setups. • Polymer protonation provided changeable sensitivities. • Color and morphological variation confirm polymer aggregation and electrical changes.
Sensitivity of neuroprogenitor cells to chemical-induced apoptosis using a multiplexed assay suitable for high-throughput screening*
AbstractHigh-throughput methods are useful for rapidly screening large numbers of chemicals for biological activity, including the perturbation of pathways that may lead to adverse cellular effects. In vitro assays for the key events of neurodevelopment, including apoptosis, may ...
The critical review of methodologies and approaches to assess the inherent skin sensitization potential (skin allergies) of chemicals. Part II
Thyssen, Jacob P; Giménez-Arnau, Elena; Lepoittevin, Jean-Pierre
To identify specific cases, classes or specific use situations of chemicals for which 'safety thresholds' or 'safety limits' were set (in regulations, standards, in scientific research/clinical work, etc.) and critically review the scientific and methodological parameters used to set those limits....
Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.
Part 1 (10.1021/ef3014103) of this series describes a new rotary reactor for gas-fueled chemical-looping combustion (CLC), in which, a solid wheel with microchannels rotates between the reducing and oxidizing streams. The oxygen carrier (OC) coated
Assen, Ayalew Hussen Assen; Yassine, Omar; Shekhah, Osama; Eddaoudi, Mohamed; Salama, Khaled N.
This work reports on the fabrication and deployment of a select metal-organic framework (MOF) thin film as an advanced chemical capacitive sensor for the sensing/detection of ammonia (NH3) at room temperature. Namely, the MOF thin film sensing layer
In-Doped ZnO Hexagonal Stepped Nanorods and Nanodisks as Potential Scaffold for Highly-Sensitive Phenyl Hydrazine Chemical Sensors.
Umar, Ahmad; Kim, Sang Hoon; Kumar, Rajesh; Al-Assiri, Mohammad S; Al-Salami, A E; Ibrahim, Ahmed A; Baskoutas, Sotirios
Herein, we report the growth of In-doped ZnO (IZO) nanomaterials, i.e., stepped hexagonal nanorods and nanodisks by the thermal evaporation process using metallic zinc and indium powders in the presence of oxygen. The as-grown IZO nanomaterials were investigated by several techniques in order to examine their morphological, structural, compositional and optical properties. The detailed investigations confirmed that the grown nanomaterials, i.e., nanorods and nanodisks possess well-crystallinity with wurtzite hexagonal phase and grown in high density. The room-temperature PL spectra exhibited a suppressed UV emissions with strong green emissions for both In-doped ZnO nanomaterials, i.e., nanorods and nanodisks. From an application point of view, the grown IZO nanomaterials were used as a potential scaffold to fabricate sensitive phenyl hydrazine chemical sensors based on the I-V technique. The observed sensitivities of the fabricated sensors based on IZO nanorods and nanodisks were 70.43 μA·mM -1 cm -2 and 130.18 μA·mM -1 cm -2 , respectively. For both the fabricated sensors, the experimental detection limit was 0.5 μM, while the linear range was 0.5 μM-5.0 mM. The observed results revealed that the simply grown IZO nanomaterials could efficiently be used to fabricate highly sensitive chemical sensors.
Chemical surface treatment with toluene to enhance sensitivity of NO2 gas sensors based on CuPcTs/Alq3 thin films
Mahdi H. Suhail
Full Text Available A nitrogen dioxide (NO2 gas sensor based on the blend of copper phthalocyanine-tetrasulfonic acid tetrasodium/tris-(8-hydroxyquinolinealuminum (CuPcTs/Alq3 thin films was fabricated. The effect of chemical surface treatment with toluene on the structural, surface morphology and device sensitivity has been examined. The X-ray diffraction (XRD patterns of as-deposited and toluene-treated films exhibit a broad hump peak at 2θ = 24°. The atomic force microscopy (AFM measurements show that the average particle diameter decreases with immersing time. The needle like shapes can be seen from scanning electron microscopy (SEM images for films treated with toluene for an immersing time of 60 min. Gas sensor characterizations demonstrate that all samples have superior NO2 gas sensitivity at a operating temperature of 373 K. The increase of the sensor sensitivity with increasing chemical treatment time up to 60 min was observed. All films show the stable and repeatable response patterns.
Incorporation of Mn2+ into CdSe quantum dots by chemical bath co-deposition method for photovoltaic enhancement of quantum dot-sensitized solar cells.
Zhang, Chenguang; Liu, Shaowen; Liu, Xingwei; Deng, Fei; Xiong, Yan; Tsai, Fang-Chang
A photoelectric conversion efficiency (PCE) of 4.9% was obtained under 100 mW cm -2 illumination by quantum-dot-sensitized solar cells (QDSSCs) using a CdS/Mn : CdSe sensitizer. CdS quantum dots (QDs) were deposited on a TiO 2 mesoporous oxide film by successive ionic layer absorption and reaction. Mn 2+ doping into CdSe QDs is an innovative and simple method-chemical bath co-deposition, that is, mixing the Mn ion source with CdSe precursor solution for Mn : CdSe QD deposition. Compared with the CdS/CdSe sensitizer without Mn 2+ incorporation, the PCE was increased from 3.4% to 4.9%. The effects of Mn 2+ doping on the chemical, physical and photovoltaic properties of the QDSSCs were investigated by energy dispersive spectrometry, absorption spectroscopy, photocurrent density-voltage characteristics and electrochemical impedance spectroscopy. Mn-doped CdSe QDs in QDSSCs can obtain superior light absorption, faster electron transport and slower charge recombination than CdSe QDs.
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 11, Revision 2 (FGE.11Rev2): Aliphatic dialcohols, diketones, and hydroxyketones from chemical groups 8 and 10
The Scientific Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (the Panel) was asked to provide scientific advice to the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs in the Member States. In particular......, the Panel was requested to evaluate 12 flavouring substances in the Flavouring Group Evaluation 11, Revision 2 (FGE.11Rev2), using the Procedure as referred to in the Commission Regulation (EC) No 1565/2000. These 12 flavouring substances belong to chemical group 10, Annex I of the Commission Regulation (EC...... is a tertiary alcohol) [FL-no: 07.097, 07.165 and 07.184] all belonging to chemical groups 8 and 10. One of the 12 candidate substances possesses four chiral centres [FL-no: 06.134] two possesses two chiral centres [FL-no: 02.133 and 07.168] and four substances possesses one chiral centre [FL-no: 07.097, 07...
Time-of-flight secondary ion mass spectrometry with energetic cluster ion impact ionization for highly sensitive chemical structure characterization
Hirata, K., E-mail: k.hirata@aist.go.jp [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Saitoh, Y.; Chiba, A.; Yamada, K.; Narumi, K. [Takasaki Advanced Radiation Research Institute (TARRI), Japan Atomic Energy Agency (JAEA), Takasaki, Gumma 370-1292 (Japan)
Energetic cluster ions with energies of the order of sub MeV or greater were applied to time-of-flight (TOF) secondary ion (SI) mass spectrometry. This gave various advantages including enhancement of SIs required for chemical structure characterization and prevention of charging effects in SI mass spectra for organic targets. We report some characteristic features of TOF SI mass spectrometry using energetic cluster ion impact ionization and discuss two future applications of it.
Sensitivity of simulated convection-driven stratosphere-troposphere exchange in WRF-Chem to the choice of physical and chemical parameterization
Phoenix, Daniel B.; Homeyer, Cameron R.; Barth, Mary C.
Tropopause-penetrating convection is capable of rapidly transporting air from the lower troposphere to the upper troposphere and lower stratosphere (UTLS), where it can have important impacts on chemistry, the radiative budget, and climate. However, obtaining in situ measurements of convection and convective transport is difficult and such observations are historically rare. Modeling studies, on the other hand, offer the advantage of providing output related to the physical, dynamical, and chemical characteristics of storms and their environments at fine spatial and temporal scales. Since these characteristics of simulated convection depend on the chosen model design, we examine the sensitivity of simulated convective transport to the choice of physical (bulk microphysics or BMP and planetary boundary layer or PBL) and chemical parameterizations in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). In particular, we simulate multiple cases where in situ observations are available from the recent (2012) Deep Convective Clouds and Chemistry (DC3) experiment. Model output is evaluated using ground-based radar observations of each storm and in situ trace gas observations from two aircraft operated during the DC3 experiment. Model results show measurable sensitivity of the physical characteristics of a storm and the transport of water vapor and additional trace gases into the UTLS to the choice of BMP. The physical characteristics of the storm and transport of insoluble trace gases are largely insensitive to the choice of PBL scheme and chemical mechanism, though several soluble trace gases (e.g., SO2, CH2O, and HNO3) exhibit some measurable sensitivity.
Allergic contact dermatitis from resin hardeners during the manufacture of thermosetting coating paints.
Foulds, I S; Koh, D
5 production operators from 2 factories manufacturing thermosetting coating paint developed work-related skin disorders within 12 months of the introduction of a new powdered paint product. All 5 workers were found to have allergic contact dermatitis from 2 epoxy resin hardeners, both of which were commercial preparations of triglycidyl isocyanurate (TGIC). 2 of the workers had concomitant sensitization to epoxy resin in the standard series and several of the epoxy resin preparations at the workplace. TGIC has been reported as a contact sensitizer both in persons producing the chemical and among end-users of TGIC-containing products. These 5 reported cases document allergic contact dermatitis from commercial TGIC among exposed workers during an intermediate process of powdered paint manufacture. The possibility of substituting this epoxy resin hardener with less sensitizing alternatives should be explored.
Gene expression profiling in persons with multiple chemical sensitivity before and after a controlled n-butanol exposure session
was that unexposed and symptom-free MCS participants have similar gene expression patterns to controls and a second hypothesis that MCS participants can be separated from controls based on differential gene expression upon a controlled n-butanol exposure. Participants were exposed to 3.7 ppm n-butanol while seated...... min after being exposed to and 4 hours after the exposure. Participants suffering from MCS and healthy controls were recruited through advertisement at public places and in a local newspaper. 36 participants who considered themselves sensitive were prescreened for eligibility. 18 sensitive persons...... displayed similar gene expression levels both at baseline and after the exposure and the computed AUC values were likewise comparable between the 2 groups. The intragroup variation in expression levels among MCS participants was noticeably greater than the controls. MCS participants and controls have...
Prospective multicenter survey on the clinical management of pediatric contact dermatitis.
Ruggiero, Giuseppe; Carnevale, Claudia; Diociaiuti, Andrea; Arcangeli, Fabio; El Hachem, May
Contact dermatitis can be defined as an inflammatory process affecting the skin surface and induced by contact with chemical, physical and/or biotic agents in the environment. It causes lesions to skin, mucosae and semi-mucosae by means of allergic and irritant pathogenic mechanisms. Among the main triggers of contact dermatitis in the pediatric age are chemical or physical agents, which cause irritant contact dermatitis (ICD), and sensitizers, which cause a tissue damage through an allergic mechanism (allergic contact dermatitis [ACD]). A prospective, multicenter, observational study was carried out in 204 children affected by contact dermatitis, aged up to 14 years, and enrolled by pediatricians from 7 different Italian provinces. The diagnosis of contact dermatitis was based on the pediatrician's clinical evaluation. The data were collected through a series of simple and multiple choice questions, anonymously filled out by pediatricians. In 90% of cases (184 of 204 patients), there was complete remission of contact dermatitis, with no cases of worsening. No adverse events were observed, either. The effectiveness of the therapy was rated as "very effective" by 84.4% of the parents and 86.8% of the pediatricians. In only 10 patients a new therapy had to be prescribed. Contact dermatitis is a heterogeneous inflammatory skin disease induced by contact with different kinds of environmental agents. Cutaneous manifestations are highly variable and depend on the modality of contact, on the causative agent and on the pathogenesis. This Italian experience of a clinical approach to contact dermatitis stresses the need of daily skin care through different therapeutic strategies, based on the diagnosis, the clinical severity and the parents and children compliance. The first therapeutic measure to be implemented is prevention, through the removal of the causative agent and the use of protective devices. Indeed, preserving the skin's barrier function is an important goal and
Sensitivity analysis in molecular dynamics and chemical kinetics and a theory of intramolecular energy transfer in the presence of intense radiation fields
Eslava, L.A.
This thesis is an investigation of two topics in the area of molecular and chemical dynamics phenomena. The first topic, Sensitivity Analysis in Molecular Dynamics and Chemical Kinetics, explores the response of the numerical solutions to variation in the input information. After a brief consideration of elementary sensitivity coefficients (i.e. partial derivatives of observables with respect to model parameters), attention is focused on an entire new family of derived coefficients capable of exhibiting important aspects of the underlying dynamics. Each derived sensitivity coefficient has a unique physical interpretation in terms of an experiment or modeling calculation. Also, a fitting model for rotationally inelastic cross sections that accurately predicts cross sections away from the region of parameter space used in the fitting is presented. The global behavior of cross sections in parameter space is examined, and a nonlinear interpolation formula is suggested which utilizes sensitivity information. The second topic, A Theory of Intramolecular Energy Transfer in the Presence of Intense Radiation Fields, represents a theoretical formulation of energy redistribution based on stochastic considerations. The fundamental assumption is that a random phase approximation is valid at specific time intervals. This results in the replacement of the Schrodinger equation by a master-type equation, which is further approximated by a Fokker-Planck diffusion like equation. Energy transfer is described as a flow of probability among the quantum states, and the dissociation of dynamics are embodied in the boundary conditions. By virtue of the continuous character of the Fokker-Planck equation, the computational difficulty of its numerical solution depends only on the number of degrees of freedom and not on the number of states
Graphene oxide as sensitive layer in Love-wave surface acoustic wave sensors for the detection of chemical warfare agent simulants.
Sayago, Isabel; Matatagui, Daniel; Fernández, María Jesús; Fontecha, José Luis; Jurewicz, Izabela; Garriga, Rosa; Muñoz, Edgar
A Love-wave device with graphene oxide (GO) as sensitive layer has been developed for the detection of chemical warfare agent (CWA) simulants. Sensitive films were fabricated by airbrushing GO dispersions onto Love-wave devices. The resulting Love-wave sensors detected very low CWA simulant concentrations in synthetic air at room temperature (as low as 0.2 ppm for dimethyl-methylphosphonate, DMMP, a simulant of sarin nerve gas, and 0.75 ppm for dipropylene glycol monomethyl ether, DPGME, a simulant of nitrogen mustard). High responses to DMMP and DPGME were obtained with sensitivities of 3087 and 760 Hz/ppm respectively. Very low limit of detection (LOD) values (9 and 40 ppb for DMMP and DPGME, respectively) were calculated from the achieved experimental data. The sensor exhibited outstanding sensitivity, good linearity and repeatability to all simulants tested. The detection mechanism is here explained in terms of hydrogen bonding formation between the tested CWA simulants and GO. Copyright © 2015 Elsevier B.V. All rights reserved.
Highly sensitive and selective room-temperature NO{sub 2} gas sensor based on bilayer transferred chemical vapor deposited graphene
Seekaew, Yotsarayuth [Department of Physics, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900 (Thailand); Phokharatkul, Ditsayut; Wisitsoraat, Anurat [Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, Klong Luang, Pathumthani 12120 (Thailand); Wongchoosuk, Chatchawal, E-mail: chatchawal.w@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900 (Thailand)
Highlights: • Simple and low-cost fabrication of bilayer graphene gas sensor was presented. • Layer effects of graphene on NO{sub 2} gas-sensing properties were investigated. • Bilayer graphene sensor exhibited a high linear NO{sub 2} sensitivity of 1.409 ppm{sup −1}. • The NO{sub 2}-sensing mechanisms based on band diagram were highlighted. - Abstract: This work presents a highly sensitive room-temperature gas sensor based on bilayer graphene fabricated by an interfacial transfer of chemical vapor deposited graphene onto nickel interdigitated electrodes. Scanning electron microscopic and Raman spectroscopic characterizations confirm the presence of graphene on interdigitated nickel electrodes with varying numbers of graphene layers. The NO{sub 2} detection performances of bilayer graphene gas sensor have been investigated in comparison with those of monolayer and multilayer graphene gas sensors at room temperature. From results, the bilayer graphene gas sensor exhibits higher response, sensitivity and selectivity to NO{sub 2} than monolayer and multilayer graphene. The sensitivity of bilayer graphene gas sensor is 1.409 ppm{sup −1} towards NO{sub 2} over a concentration range of 1–25 ppm, which is more than twice higher than that of monolayer graphene. The NO{sub 2}-sensing mechanism of graphene sensing film has been explained based on the direct charge transfer process due to the adsorption of NO{sub 2} molecules.
The Different Sensitive Behaviors of a Hydrogen-Bond Acidic Polymer-Coated SAW Sensor for Chemical Warfare Agents and Their Simulants
Yin Long
Full Text Available A linear hydrogen-bond acidic (HBA linear functionalized polymer (PLF, was deposited onto a bare surface acoustic wave (SAW device to fabricate a chemical sensor. Real-time responses of the sensor to a series of compounds including sarin (GB, dimethyl methylphosphonate (DMMP, mustard gas (HD, chloroethyl ethyl sulphide (2-CEES, 1,5-dichloropentane (DCP and some organic solvents were studied. The results show that the sensor is highly sensitive to GB and DMMP, and has low sensitivity to HD and DCP, as expected. However, the sensor possesses an unexpected high sensitivity toward 2-CEES. This good sensing performance can't be solely or mainly attributed to the dipole-dipole interaction since the sensor is not sensitive to some high polarity solvents. We believe the lone pair electrons around the sulphur atom of 2-CEES provide an electron-rich site, which facilitates the formation of hydrogen bonding between PLF and 2-CEES. On the contrary, the electron cloud on the sulphur atom of the HD molecule is offset or depleted by its two neighbouring strong electron-withdrawing groups, hence, hydrogen bonding can hardly be formed.
Development of LLNA:DAE: a new local lymph node assay that includes the elicitation phase, discriminates borderline-positive chemicals, and is useful for cross-sensitization testing.
We developed a new local lymph node assay (LLNA) that includes the elicitation phase termed LLNA:DAE for discrimination of borderline-positive chemicals as classified by the LLNA modified by Daicel based on ATP content (LLNA:DA) and for cross-sensitization testing. Although the LLNA:DA method could help identify skin sensitizers, some skin irritants classified as non-sensitizers by the LLNA were classified as borderline positive. In addition, the evaluation for the cross-sensitization potential between chemicals was impossible. In the LLNA:DAE procedure, test group of mice received four applications of chemicals on the dorsum of the right ear for induction and one application on the dorsum of the left ear for elicitation. Control group of mice received one chemical application on the dorsum of the left ear. We evaluated the sensitizing potential by comparing the weights of the lymph nodes from the left ears between the two groups. The results of using the LLNA:DAE method to examine 24 chemicals, which contained borderline-positive chemicals, were consistent with those from the LLNA method, except for nickel chloride (NiCl2). Two chemical pairs, 2,4-dinitrochlorobenzene (DNCB) with 2,4-dinitrofluorobenzene (DNFB) and hydroquinone (HQ) with p-benzoquinone (p-BQ), showed clear cross-sensitization with each other, while another chemical pair, DNFB with hexylcinnamic aldehyde (HCA) did not. Taken together, our results suggest that the LLNA:DAE method is useful for discriminating borderline-positive chemicals and for determining chemical cross-sensitization.
EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Flavouring Group Evaluation 46, Revision 1 (FGE.46Rev1): Ammonia and three ammonium salts from chemical group 30
The Scientific Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (the Panel) was asked to provide scientific advice to the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs in the Member States. In particular...... in a wide range of food items up to very high amounts. Hydrogen sulphide is also reported to occur naturally in a wide range of food items. In its evaluation, the Panel as a default used the "Maximised Survey-derived Daily Intake� (MSDI) approach to estimate the per capita intakes of the flavouring...... substances in Europe. However, when the Panel examined the information provided by the European Flavouring Industry on the use levels in various foods, it appeared obvious that the MSDI approach in a number of cases would grossly underestimate the intake by regular consumers of products flavoured at the use...
... Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More sharing ... www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative Contact ...
Application of Photocured Polymer Ion Selective Membranes for Solid-State Chemical Sensors
Natalia Abramova
Full Text Available Application of conducting polymers with additional functional groups for a solid contact formation and photocurable membranes as sensitive elements of solid-state chemical sensors is discussed. Problems associated with application of UV-curable polymers for sensors are analyzed. A method of sensor fabrication using copolymerized conductive layer and sensitive membrane is presented and the proof of concept is confirmed by two examples of solid-contact electrodes for Ca ions and pH.
Evaluation of the skin sensitizing potency of chemicals by using the existing methods and considerations of relevance for elicitation
Basketter, David A; Andersen, Klaus E; Liden, Carola
be translated into practical thresholds and whether these could be set for both induction and elicitation. Examples are given for substances falling into various potency groups for skin sensitization relating to results from the local lymph node assay, the guinea pig maximization test, the Buehler method...... products, cosmetics, food and feeding stuffs, which are subject to specific community legislation. The main questions that are answered in this report are whether it would be possible to give detailed guidance on how to grade allergen potency based on the existing methods, whether such grading could...
Assessment of the U937 cell line for the detection of contact allergens
Python, Francois; Goebel, Carsten; Aeby, Pierre
The human myeloid cell line U937 was evaluated as an in vitro test system to identify contact sensitizers in order to develop alternatives to animal tests for the cosmetic industry. Specific culture conditions (i.e., presence of interleukin-4, IL-4) were applied to obtain a dendritic cell-like phenotype. In the described test protocol, these cells were exposed to test chemicals and then analyzed by flow cytometry for CD86 expression and by quantitative real-time reverse transcriptase-polymerase chain reaction for IL-1β and IL-8 gene expressions. Eight sensitizers, three non-sensitizers and five oxidative hair dye precursors were examined after 24-, 48- and 72-h exposure times. Test item-specific modulations of the chosen activation markers (CD86, IL-1β and IL-8) suggest that this U937 activation test could discriminate test items classified as contact sensitizers or non-sensitizers in the local lymph node assay in mice (LLNA). More specifically, a test item can be considered as a potential sensitizer when it significantly induced the upregulation of the expression of at least two markers. Using this approach, we could correctly evaluate the dendritic cell (DC) activation potential for 15 out of 16 tested chemicals. We conclude that the U937 activation test may represent an useful tool in a future in vitro test battery for predicting sensitizing properties of chemicals
Future needs and recommendations in the development of species sensitivity distributions: Estimating toxicity thresholds for aquatic ecological communities and assessing impacts of chemical exposures.
Belanger, Scott; Barron, Mace; Craig, Peter; Dyer, Scott; Galay-Burgos, Malyka; Hamer, Mick; Marshall, Stuart; Posthuma, Leo; Raimondo, Sandy; Whitehouse, Paul
A species sensitivity distribution (SSD) is a probability model of the variation of species sensitivities to a stressor, in particular chemical exposure. The SSD approach has been used as a decision support tool in environmental protection and management since the 1980s, and the ecotoxicological, statistical, and regulatory basis and applications continue to evolve. This article summarizes the findings of a 2014 workshop held by the European Centre for Toxicology and Ecotoxicology of Chemicals and the UK Environment Agency in Amsterdam, The Netherlands, on the ecological relevance, statistical basis, and regulatory applications of SSDs. An array of research recommendations categorized under the topical areas of use of SSDs, ecological considerations, guideline considerations, method development and validation, toxicity data, mechanistic understanding, and uncertainty were identified and prioritized. A rationale for the most critical research needs identified in the workshop is provided. The workshop reviewed the technical basis and historical development and application of SSDs, described approaches to estimating generic and scenario-specific SSD-based thresholds, evaluated utility and application of SSDs as diagnostic tools, and presented new statistical approaches to formulate SSDs. Collectively, these address many of the research needs to expand and improve their application. The highest priority work, from a pragmatic regulatory point of view, is to develop a guidance of best practices that could act as a basis for global harmonization and discussions regarding the SSD methodology and tools. Integr Environ Assess Manag 2017;13:664-674. © 2016 SETAC. © 2016 SETAC.
Dermatite de contato por metais: prevalência de sensibilização ao níquel, cobalto e cromo Metal contact dermatitis: prevalence of sensitization to nickel, cobalt and chromium
Full Text Available FUNDAMENTOS: Dermatite de contato (DC por metais é dermatose comum em diversos grupos populacionais. OBJETIVOS: Caracterizar o grupo com DC ao níquel, cromo e cobalto na população estudada, determinar a prevalência da sensibilização aos mesmos, verificar as combinações de testes positivos e comparar com a literatura. CASU�STICAS E MÉTODOS: Foram realizados testes epicutâneos em 1.208 pacientes com hipótese diagnóstica de DC. Selecionaram-se aqueles com testes positivos aos metais. RESULTADOS: Obtiveram-se 404 pacientes (33,5% da amostra com pelo menos um teste positivo ao níquel e/ou cobalto e/ou cromo. Foram 487 testes positivos a metais, correspondendo a 48% de todos os testes positivos. A maioria dos pacientes era do sexo feminino (72%, de cor branca (54%, com idade entre 40 e 49 anos (25% empregada na área de limpeza (59%. Dos 404, 329 (81,5% foram positivos a apenas um tipo de metal, sendo 60% com teste positivo ao níquel, 13% ao cromo e 8,5% ao cobalto. Cerca de 18,5% apresentaram testes positivos a dois ou três metais, sendo a associação níquel/cobalto a mais comum. CONCLUSÕES: A sensibilização aos metais foi de 48%, entre os testes positivos e ocorreu principalmente em mulheres da cor branca, na faixa etária de 40 a 49 anos e sem correlação ocupacional. A maioria apresentou sensibilização a apenas um metal. Esses dados são semelhantes aos de outros trabalhos já publicados.BACKGROUND: Metal contact dermatitis (nickel, cobalt and chromium is a common dermatosis among several population groups. OBJECTIVE: To describe the individuals with metal contact dermatitis in the group studied, to determine the prevalence of skin sensitization by nickel, cobalt and chromium, to verify the positive test combinations among these three substances and to compare our results with the literature. PATIENTS AND METHODS: Patch test was performed in 1208 patients with a presumptive diagnosis of contact dermatitis. Those with
Radiation sensitizations at DNA-level by chemical and biological agents. Coordinated programme on improvement of radiotherapy of cancer using modifiers of radiosensitivity of cells
Altmann, H.
Radiation sensitization by chemical agents at DNA level is discussed. Procaine, Halothan and Metronidazole showed no significant effect on unscheduled DNA synthesis (UDS) in mouse spleen cells, investigated by autoradiography and no effect on rejoining of DNA single strand breaks after gamma or UV irradiation. Oxyphenbutazon and prednisolone reduced the replicative DNA synthesis in vitro and in vivo but there was only little effect on DNA repair in the in vivo experiments. These two substances showed also a small reduction in poly(ADP-ribose) synthesis (PAR synthesis). 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) in combination with UV irradiation showed that 5-MOP was more toxic than mutagen, but induced much less DNA crosslinks than 8-MOP. Autoradiographic studies of radiation sensitization by biological agents showed significant inhibition of UDS in Yoshida tumor cells after acute mycoplasma infection in rats. Nucleoid sedimentation studies showed only in the case of Yoshida tumor cells after mycoplasma infection a dramatic effect in the sedimentation behaviour. Sensitization of cells by changing chromatin structure was also studied. Benzamide, 3-NH 2 -benzamide, 3-Methoxybenzamide, Spermine, Theophyllin and Caffeine were tested in different concentrations on replicative DNA synthesis, UDS after UV irradiation and PAR synthesis Chinese hamster ovary cells. 5-Methoxybenzamide was the strongest sensitizer and inhibitor of the PAR synthesis, and was used in further experiments. Results of KFA Juelich on sensitization of a mamma-adenocarcinoma EO 771 on C57 B1 mice are given. Replicative DNA synthesis, DNA repair and PAR synthesis were compared in spleen cells and adenocarcinoma cells after treatment with 5-Methoxybenzamide. An inhibitory effect on UDS could be shown only in adenocarcinoma cells but not in the mice spleen cells
Fragrance contact allergy: a clinical review.
Most people in modern society are exposed daily to fragrance ingredients from one or more sources. Fragrance ingredients are also one of the most frequent causes of contact allergic reactions. The diagnosis is made by patch testing with a mixture of fragrance ingredients, the fragrance mix. This gives a positive patch-test reaction in about 10% of tested patients with eczema, and the most recent estimates show that 1.7-4.1% of the general population are sensitized to ingredients of the fragrance mix. Fragrance allergy occurs predominantly in women with facial or hand eczema. These women typically have a history of rash to a fine fragrance or scented deodorants. Chemical analysis has revealed that well known allergens from the fragrance mix are present in 15-100% of cosmetic products, including deodorants and fine fragrances, and most often in combinations of three to four allergens in the same products. This means that it is difficult to avoid exposure, as products labelled as 'fragrance free' have also been shown to contain fragrance ingredients, either because of the use of fragrance ingredients as preservatives or masking perfumes, or the use of botanicals. About 2500 different fragrance ingredients are currently used in the composition of perfumes and at least 100 of these are known contact allergens. Therefore, it is advisable to supplement standard patch testing with the patient's own stay-on cosmetic products, as well as the fragrance chemical hydroxyisohexyl-3-cyclohexane carboxaldehyde, which on its own gives responses in 1-3% of tested patients. The focus in recent years on the ingredients of the fragrance mix will probably result in the fragrance industry changing the composition of perfumes, and thus make the current diagnostic test less useful. New diagnostic tests are under development to identify contact allergy to new allergens, reflecting the continuous developments and trends in exposure.
Schottky-contact plasmonic rectenna for biosensing
Alavirad, Mohammad; Siadat Mousavi, Saba; Roy, Langis; Berini, Pierre
We propose a plasmonic gold nanodipole array on silicon, forming a Schottky contact thereon, and covered by water. The behavior of this array under normal excitation has been extensively investigated. Trends have been found and confirmed by identification of the mode propagating in nanodipoles and its properties. This device can be used to detect infrared radiation below the bandgap energy of the substrate via internal photoelectric effect (IPE). Also we estimate its responsivity and detection limit. Finally, we assess the potential of the structure for bulk and surface (bio) chemical sensing. Based on modal results an analytical model has been proposed to estimate the sensitivity of the device. Results show a good agreement between numerical and analytical interpretations.
Footwear dermatitis - Clinical patterns and contact allergens
Handa S
Full Text Available Thirty patients suspected of contact dermatitis to footwear studied to evaluate various clinical presentations and possible sensitizers. ′V′ chappals and sandals were suspected alone in 12, a combination of open and closed shoes in 15 and closed shoes alone in 3 patients. Commonest affected sites were dorsa of feet and toes in 14 and dorsa of feet corresponding to the shape of footwear in 12 patients. Patch tests were done using a battery of sixteen allergens. Positive patch tests were seen in 29 patients. Rubber chemicals were the commonest allergens detected in 26 patients, dyes in 10,leather in 6, glues and neoprene cements in 4 and rubber material from suspected footwear as such in 4 patients respectively.
Chemical synthesis of CdS onto TiO2 nanorods for quantum dot sensitized solar cells
Pawar, Sachin A.; Patil, Dipali S.; Lokhande, Abhishek C.; Gang, Myeng Gil; Shin, Jae Cheol; Patil, Pramod S.; Kim, Jin Hyeok
A quantum dot sensitized solar cell (QDSSC) is fabricated using hydrothermally grown TiO2 nanorods and successive ionic layer adsorption and reaction (SILAR) deposited CdS. Surface morphology of the TiO2 films coated with different SILAR cycles of CdS is examined by Scanning Electron Microscopy which revealed aggregated CdS QDs coverage grow on increasing onto the TiO2 nanorods with respect to cycle number. Under AM 1.5G illumination, we found the TiO2/CdS QDSSC photoelectrode shows a power conversion efficiency of 1.75%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.04 mA/cm2 which is higher than that of a bare TiO2 nanorods array.
Highly Sensitive Magnetic-SERS Dual-Function Silica Nanoprobes for Effective On-Site Organic Chemical Detection
Jeong, Cheolhwan; Kim, Hyung-Mo; Park, So Yeon; Cha, Myeong Geun; Park, Sung-Jun; Kyeong, San; Pham, Xuan-Hung; Hahm, Eunil; Ha, Yuna; Jeong, Dae Hong; Jun, Bong-Hyun; Lee, Yoon-Sik
We report magnetic silver nanoshells (M-AgNSs) that have both magnetic and SERS properties for SERS-based detection. The M-AgNSs are composed of hundreds of Fe3O4 nanoparticles for rapid accumulation and bumpy silver shell for sensitive SERS detection by near-infrared laser excitation. The intensity of the SERS signal from the M-AgNSs was strong enough to provide single particle-level detection. We obtained much stronger SERS signal intensity from the aggregated M-AgNSs than from the non-aggregated AgNSs. 4-Fluorothiophenol was detected at concentrations as low as 1 nM, which corresponds to 0.16 ppb. The limit of detection for tetramethylthiuram disulfide was 10 μM, which corresponds to 3 ppm. The M-AgNSs can be used to detect trace amounts of organic molecules using a portable Raman system. PMID:28608835
Cheolhwan Jeong
Full Text Available We report magnetic silver nanoshells (M-AgNSs that have both magnetic and SERS properties for SERS-based detection. The M-AgNSs are composed of hundreds of Fe3O4 nanoparticles for rapid accumulation and bumpy silver shell for sensitive SERS detection by near-infrared laser excitation. The intensity of the SERS signal from the M-AgNSs was strong enough to provide single particle-level detection. We obtained much stronger SERS signal intensity from the aggregated M-AgNSs than from the non-aggregated AgNSs. 4-Fluorothiophenol was detected at concentrations as low as 1 nM, which corresponds to 0.16 ppb. The limit of detection for tetramethylthiuram disulfide was 10 μM, which corresponds to 3 ppm. The M-AgNSs can be used to detect trace amounts of organic molecules using a portable Raman system.
A STUDY ON CONTACT DERMATITIS TO HAIR DYE AND HENNA
Neerja Puri
Full Text Available P- Phenylenediamine is an oxidative chemical that is frequently used as a permanent hair-coloring agent. It is added to henna to increase the intensity and longevity of the tattoo and expedites its drying time. Henna itself is a greenish brown vegetable coloring made from the leaves of Lawsonia inermis and rarely causes allergic contact dermatitis. The addition of PPD causes the contact sensitization to black henna. Serious adverse skin reactions to permanent hair dyes and temporary black tattoos have been reported. As temporary tattoos have become fashionable among adolescents, the risk profile for p-phenylenediamine (PPD sensitization of the population has changed simultaneously with an increasing use of hair dyes in this age group. With increased popularity of body art such as body piercing and tattooing, an increase in temporary henna tattoos has also occurred. Although the appeal of non-permanence exists for henna tattoos, dermatologists have begun to see numerous cases of allergic contact dermatitis linked with a certain type of henna. We selected 50 patients using hair dye and henna for our study. Patch testing was done in all the patients using Indian standard series of antigens. Regarding to the side effects to hair dye and henna and itching was the commonest symptom seen in 16% patients, erythematous scaly plaques were seen in 10% patients, vesicular reactions were seen in 6% patients, angioneurotic oedema and contact urticaria was seen in 4% patients each and anaphylaxis and keloidal reaction was seen in 2% patients each.
Chemically stable Au nanorods as probes for sensitive surface enhanced scattering (SERS) analysis of blue BIC ballpoint pens
Alyami, Abeer; Saviello, Daniela; McAuliffe, Micheal A. P.; Cucciniello, Raffaele; Mirabile, Antonio; Proto, Antonio; Lewis, Liam; Iacopino, Daniela
Au nanorods were used as an alternative to commonly used Ag nanoparticles as Surface Enhanced Raman Scattering (SERS) probes for identification of dye composition of blue BIC ballpoint pens. When used in combination with Thin Layer Chromatography (TLC), Au nanorod colloids allowed identification of the major dye components of the BIC pen ink, otherwise not identifiable by normal Raman spectroscopy. Thanks to their enhanced chemical stability compared to Ag colloids, Au nanorods provided stable and reproducible SERS signals and allowed easy identification of phthalocyanine and triarylene dyes in the pen ink mixture. These findings were supported by FTIR and MALDI analyses, also performed on the pen ink. Furthermore, the self-assembly of Au nanorods into large area ordered superstructures allowed identification of BIC pen traces. SERS spectra of good intensity and high reproducibility were obtained using Au nanorod vertical arrays, due to the high density of hot spots and morphological reproducibility of these superstructures. These results open the way to the employment of SERS for fast screening analysis and for quantitative analysis of pens and faded pens which are relevant for the fields of forensic and art conservation sciences.
Highly sensitive sorption-luminescence determination of trace europium with preconcentration on silica chemically modified with iminodiacetic acid
Voronina, R.D.; Zorov, N.B.
Features of a sorption-luminescence method for the determination of trace europium were studied. The method includes the preliminary sorption of europium at pH 7.1 from solutions with silica chemically modified with iminodiacetic acid, the subsequent treatment of the sorbent with 2-thenoyltrifluoroacetone at pH 8.0, and the measurement of the intensity of luminescence of the surface three-component europium complex at 613 nm. The effect of moisture as the quencher of luminescence of the surface europium complex was studied, and techniques for its removal were proposed. Sorption in the static mode provides the detection limit of europium of 7 x 10 -5 g/ml. The calibration plot is linear in the range of two orders of magnitude of europium concentration in solutions. The relative standard deviation in the determination of 1.5 x 10 -2 μg/ml europium is 5%. In the dynamic mode of sorption from 1000 ml of an analyzed solution with the use of sorption-desorption, the detection limit of europium of 8 x 10 -7 μg/ml was attained [ru
Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity.
Kenichi Azuma
Full Text Available Multiple chemical sensitivity (MCS is a disorder characterized by nonspecific and recurrent symptoms from various organ systems associated with exposure to low levels of chemicals. Patients with MCS process odors differently than controls do. Previously, we suggested that this odor processing was associated with increased regional cerebral blood flow (rCBF in the prefrontal area during olfactory stimulation using near-infrared spectroscopic (NIRS imaging. The aim of this study was to investigate the association of odor thresholds and changes in rCBF during olfactory stimulation at odor threshold levels in patients with MCS. We investigated changes in the prefrontal area using NIRS imaging and a T&T olfactometer during olfactory stimulation with two different odorants (sweet and fecal at three concentrations (zero, odor recognition threshold, and normal perceived odor level in 10 patients with MCS and six controls. The T&T olfactometer threshold test and subjective assessment of irritating and hedonic odors were also performed. The results indicated that the scores for both unpleasant and pungent odors were significantly higher for those for sweet odors at the normal perceived level in patients with MCS than in controls. The brain responses at the recognition threshold (fecal odor and normal perceived levels (sweet and fecal odors were stronger in patients with MCS than in controls. However, significant differences in the odor detection and recognition thresholds and odor intensity score between the two groups were not observed. These brain responses may involve cognitive and memory processing systems during past exposure to chemicals. Further research regarding the cognitive features of sensory perception and memory due to past exposure to chemicals and their associations with MCS symptoms is needed.
Occupational contact urticaria and protein contact dermatitis.
Doutre, Marie-Sylvie
Irritant dermatitis and eczema are the most prevalent occupational skin diseases. Less common are immediate contact reactions such as contact urticaria and protein contact dermatitis. Occupational contact urticaria can be subdivided into two categories, immunological and non immunological. However, some agents can induce these two types of reactions. Contact urticaria to natural rubber latex is particularly frequent among health care personnel, but contact urticaria to a wide variety of other substances occurs in many other occupations. Among those at risk are cooks, bakers, butchers, restaurant personnel, veterinarians, hairdressers, florists, gardeners, and forestry workers. Protein contact dermatitis in some of these occupations is caused principally by proteins of animal or plant origin, especially among individuals with a history of atopic dermatitis. Diagnosis requires careful interrogation, clinical examination and skin tests (open tests and prick tests with immediate lecture) to identify a particular contact allergen.
Direct measurement of graphene contact resistivity to pre-deposited metal in buried contact test structure
Qaisi, Ramy M.; Smith, Casey; Ghoneim, Mohamed T.; Yu, Qingkai; Hussain, Muhammad Mustafa
We demonstrate a buried contact based novel test structure for direct contact resistivity measurement of graphene-metal interfaces. We also observe excellent contact resistivity 1 μO-cm2 without any additional surface modification suggesting that the intrinsic Au-graphene contact is sufficient for achieving devices with low contact resistance. The chemical mechanical polishing less test structure and data described herein highlights an ideal methodology for systematic screening and engineering of graphene-metal contact resistivity to enable low power high speed carbon electronics. © 2013 IEEE.
Qaisi, Ramy M.
Mechanoluminescent Contact Type Sensor
A. K. Yefremov
Full Text Available Mechanoluminescent sensing elements convert mechanical stress into optical radiation. Advantages of such sensors are the ability to generate an optical signal, solid-state, simple structure, and resistance to electromagnetic interference. Mechanoluminescent sensor implementations can possess the concentrated and distributed sensitivity, thereby allowing us to detect the field of mechanical stresses distributed across the area and in volume. Most modern semiconductor photo-detectors can detect mechanoluminescent radiation, so there are no difficulties to provide its detection when designing the mechanoluminescent sensing devices. Mechanoluminescent substances have especial sensitivity to shock loads, and this effect can be used to create a fuse the structure of which includes a target contact type sensor with a photosensitive actuator. The paper briefly describes the theoretical basics of mechanoluminiscence: a light signal emerges from the interaction of crystalline phosphor luminescence centers with electrically charged dislocations, moving due to the deformation of the crystal. A mathematical model of the mechanoluminescent conversion is represented as a functional interaction between parameters of the mechanical shock excitation and the sensor light emission. Examples of computing the optical mechanoluminescent output signal depending on the duration and peak level of impulse load are given. It is shown that the luminous flux, generated by mechanoluminescent sensing element when there is an ammunition-target collision causes the current emerging in photo-detector (photodiode that is sufficient for a typical actuator of the fuse train to operate. The potential possibility to create a contact target type sensor based on the light-sensitive mechanoluminescent sensor was proved by the calculation and simulation results.
Personal Chemical Exposure informatics
Chemical Exposure science is the study of human contact with chemicals (from manufacturing facilities, everyday products, waste) occurring in their environments and advances knowledge of the mechanisms and dynamics of events that cause or prevent adverse health outcomes. (adapted...
Contact lens surface by electron beam
Shin, Jung Hyuck; Lee, Suk Ju; Hwang, Kwang Ha; Jeon Jin
Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility
Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... Costume Contact Lenses Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored ...
Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ...
in the same products. This means that it is difficult to avoid exposure, as products labelled as 'fragrance free' have also been shown to contain fragrance ingredients, either because of the use of fragrance ingredients as preservatives or masking perfumes, or the use of botanicals. About 2500 different...... fragrance ingredients are currently used in the composition of perfumes and at least 100 of these are known contact allergens. Therefore, it is advisable to supplement standard patch testing with the patient's own stay-on cosmetic products, as well as the fragrance chemical hydroxyisohexyl-3-cyclohexane...... carboxaldehyde, which on its own gives responses in 1-3% of tested patients. The focus in recent years on the ingredients of the fragrance mix will probably result in the fragrance industry changing the composition of perfumes, and thus make the current diagnostic test less useful. New diagnostic tests are under...
Hair dye contact allergy
Søsted, Heidi; Rastogi, Suresh Chandra; Andersen, Klaus Ejner
Colouring of hair can cause severe allergic contact dermatitis. The most frequently reported hair dye allergens are p-phenylenediamine (PPD) and toluene-2,5-diamine, which are included in, respectively, the patch test standard series and the hairdressers series. The aim of the present study...... was to identify dye precursors and couplers in hair dyeing products causing clinical hair dye dermatitis and to compare the data with the contents of these compounds in a randomly selected set of similar products. The patient material comprised 9 cases of characteristic clinical allergic hair dye reaction, where...... exposure history and patch testing had identified a specific hair dye product as the cause of the reaction. The 9 products used by the patients were subjected to chemical analysis. 8 hair dye products contained toluene-2,5-diamine (0.18 to 0.98%). PPD (0.27%) was found in 1 product, and m-aminophenol (0...
Fluorescent Metal-Organic Framework (MOF) as a Highly Sensitive and Quickly Responsive Chemical Sensor for the Detection of Antibiotics in Simulated Wastewater.
Zhu, Xian-Dong; Zhang, Kun; Wang, Yu; Long, Wei-Wei; Sa, Rong-Jian; Liu, Tian-Fu; Lü, Jian
A Zn(II)-based fluorescent metal-organic framework (MOF) was synthesized and applied as a highly sensitive and quickly responsive chemical sensor for antibiotic detection in simulated wastewater. The fluorescent chemical sensor, denoted FCS-1, exhibited enhanced fluorescence derived from its highly ordered, 3D MOF structure as well as excellent water stability in the practical pH range of simulated antibiotic wastewater (pH = 3.0-9.0). Remarkably, FCS-1 was able to effectively detect a series of sulfonamide antibiotics via photoinduced electron transfer that caused detectable fluorescence quenching, with fairly low detection limits. Two influences impacting measurements related to wastewater treatment and water quality monitoring, the presence of heavy-metal ions and the pH of solutions, were studied in terms of fluorescence quenching, which was nearly unaffected in sulfonamide-antibiotic detection. Additionally, the effective detection of sulfonamide antibiotics was rationalized by the theoretical computation of the energy bands of sulfonamide antibiotics, which revealed a good match between the energy bands of FCS-1 and sulfonamide antibiotics, in connection with fluorescence quenching in this system.
FIA-automated system used to electrochemically measure nitrite and its interfering chemicals through a 1-2 DAB / Au electrode: gain of sensitivity at upper potentials
Almeida, F. L.; dos Santos Filho, S. G.; Fontes, M. B. A.
The measurement of nitrite and its interfering-chemicals (paracetamol, ascorbic acid and uric acid) was performed employing a Flow-injection Analysis (FIA) system, which was automated using solenoid valves and air-pump. It is very important to quantify nitrite from river water, food and biologic fluids due to its antibacterial capacity in moderated concentrations, or its toxicity for human health even at low concentrations (> 20 μmol L-1 in blood fluids). Electrodes of the electrochemical planar sensor were defined by silk-screen technology. The measuring electrode was made from gold paste covered with 1-2 cis Diaminobenzene (DAB), which allowed good selectivity, linearity, repeatability, stability and optimized gain of sensitivity at 0.5 VAg/AgCl Nafion®117 (6.93 μA mol-1 L mm-2) compared to 0.3 VAg/AgCl Nafion® 117. The reference electrode was obtained from silver/palladium paste modified with chloride and covered with Nafion® 117. The auxiliary electrode was made from platinum paste. It was noteworthy that nitrite response adds to the response of the studied interfering-chemicals and it is predominant for concentrations lower than 175 μmol L-1.
Fractional enrichment of proteins using [2-{sup 13}C]-glycerol as the carbon source facilitates measurement of excited state {sup 13}Cα chemical shifts with improved sensitivity
Ahlner, Alexandra; Andresen, Cecilia; Khan, Shahid N. [Linköping University, Division of Chemistry, Department of Physics, Chemistry and Biology (Sweden); Kay, Lewis E. [The University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry, One King's College Circle (Canada); Lundström, Patrik, E-mail: patlu@ifm.liu.se [Linköping University, Division of Chemistry, Department of Physics, Chemistry and Biology (Sweden)
A selective isotope labeling scheme based on the utilization of [2-{sup 13}C]-glycerol as the carbon source during protein overexpression has been evaluated for the measurement of excited state {sup 13}Cα chemical shifts using Carr–Purcell–Meiboom–Gill (CPMG) relaxation dispersion (RD) experiments. As expected, the fractional incorporation of label at the Cα positions is increased two-fold relative to labeling schemes based on [2-{sup 13}C]-glucose, effectively doubling the sensitivity of NMR experiments. Applications to a binding reaction involving an SH3 domain from the protein Abp1p and a peptide from the protein Ark1p establish that accurate excited state {sup 13}Cα chemical shifts can be obtained from RD experiments, with errors on the order of 0.06 ppm for exchange rates ranging from 100 to 1000 s{sup −1}, despite the small fraction of {sup 13}Cα–{sup 13}Cβ spin-pairs that are present for many residue types. The labeling approach described here should thus be attractive for studies of exchanging systems using {sup 13}Cα spin probes.
[Contact allergy to henna tattoos].
Steinkjer, Bjarte; Stangeland, Katarina Zak; Mikkelsen, Carsten Sauer
Tattoos with henna colours have become very popular and the prevalence of contact allergy seems to increase. This is a short review article based on our own clinical experience and literature identified through a search in PubMed with the words "henna", "paraphenylendiamin" and "allergic contact dermatitis." A case report is included. It is well documented that many experience skin reactions after henna tattoos. The cause is almost always contact allergy to the azo compound paraphenylendiamin, which is added to speed up the process and make the colour darker. Most people, including children, get henna tattoos during vacations in Asia or the Mediterranean. Established contact allergy is permanent. Many hair-colour products contain paraphenylendiamin, and persons with contact allergy against the product may develop a very strong contact allergic eczema by use of such substances. Acute reactions are treated with local cortisone products, or with systemic steroids. Cross reaction to substances with a similar chemical structure may occur. Tattoos with paraphenylendiamin-containing henna colours should be avoided.
Simplistic graphene transfer process and its impact on contact resistance
Ghoneim, Mohamed T.; Smith, Casey; Hussain, Muhammad Mustafa
Chemical vapor deposition based graphene grown on copper foil is attractive for electronic applications owing to its reliable growth process, large area coverage, and relatively defect free nature. However, transfer of the synthesized graphene to host substrate for subsequent device fabrication is extremely sensitive and can impact ultimate performance. Although ultra-high mobility is graphene's most prominent feature, problems with high contact resistance have severely limited its true potential. Therefore, we report a simple poly-(methyl methacrylate) based transfer process without post-annealing to achieve specific contact resistivity of 3.8 × 10−5 Ω cm2 which shows 80% reduction compared to previously reported values.
Ghoneim, Mohamed T.
Chemical vapor deposition based graphene grown on copper foil is attractive for electronic applications owing to its reliable growth process, large area coverage, and relatively defect free nature. However, transfer of the synthesized graphene to host substrate for subsequent device fabrication is extremely sensitive and can impact ultimate performance. Although ultra-high mobility is graphene\\'s most prominent feature, problems with high contact resistance have severely limited its true potential. Therefore, we report a simple poly-(methyl methacrylate) based transfer process without post-annealing to achieve specific contact resistivity of 3.8 × 10−5 Ω cm2 which shows 80% reduction compared to previously reported values.
Immunotherapy of allergic contact dermatitis.
Spiewak, Radoslaw
The term 'immunotherapy' refers to treating diseases by inducing, enhancing or suppressing immune responses. As allergy is an excessive, detrimental immune reaction to otherwise harmless environmental substances, immunotherapy of allergic disease is aimed at the induction of tolerance toward sensitizing antigens. This article focuses on the historical developments, present state and future outlook for immunotherapy with haptens as a therapeutic modality for allergic contact dermatitis. Inspired by the effectiveness of immunotherapy in respiratory allergies, attempts were undertaken at curing allergic contact dermatitis by means of controlled administration of the sensitizing haptens. Animal and human experiments confirmed that tolerance to haptens can be induced most effectively when the induction of tolerance precedes attempted sensitization. In real life, however, therapy is sought by people who are already sensitized and an effective reversal of hypersensitivity seems more difficult to achieve. Decades of research on Rhus hypersensitivity le