International Psychogeriatrics (5)
International Journal of Technology Assessment in Health Care (3)
Journal of Materials Research (2)
Journal of the International Neuropsychological Society (2)
Canadian Journal of Neurological Sciences (1)
Ergodic Theory and Dynamical Systems (1)
Health Technology Assessment International (3)
International Neuropsychological Society INS (2)
PP159 Making Health Technology Assessment A Common Language In Controversies: A Hidden Role For The National Evidence-Based Healthcare Collaborating Agency
Jeong-eun Park, Min Ji Lee, Eunkyo Park, Miseong Kim, Jooyeon Park
Journal: International Journal of Technology Assessment in Health Care / Volume 34 / Issue S1 / 2018
In order to improve research planning it is critical to understand how decision makers have used previous health technology assessment (HTA) results, and what expectations policy makers and health professionals have in HTA programs. In this study, we aimed to examine how HTA results have been used by decision makers, and explore complex relationships between the National Evidence-based Healthcare Collaborating Agency (NECA) and various decision-making bodies in Korea.
Three areas of healthcare decision in which NECA has been extensively involved were selected: prevention programs, single technology reimbursement, and clinical guidelines. We conducted in-depth interviews with two or three key informants from decision making bodies in each selected area. The interview participants included clinicians and government officials. We also conducted interviews with the researchers who participated in the related research to better capture the context. The interviews were analyzed using qualitative content analysis.
Eight interviews with decision makers and five interviews with researchers were conducted and analyzed. Three main themes were revealed in the data. Firstly, it was revealed that NECA was primarily expected to be an intermediary between clinicians and government. Both government and clinicians had referred to NECA's HTA results, which are expected to be scientific and impartial, when they need to reach one another on controversial topics. Secondly, there was a high need for deliberative process to resolve the conflicting interests regarding HTA results. Lastly, they wanted the HTA process to be more responsive to fast changing healthcare environments by introducing a form of rapid review.
Lack of effective communication channels between government and healthcare providers in Korea has made a room for HTA to be a common language for both sides. It is time to give up the 'one-size-fits-all' approach to conducting HTA research and tailor the research process to various needs of decision makers.
VP10 Impact Of Health Technology Assessment On Policy And Clinical Decision Making In Korea
Min Ji Lee, Jeong-eun Park, Miseong Kim, Eunkyo Park, Jooyeon Park
Published online by Cambridge University Press: 03 January 2019, p. 162
Since established in 2009, the National Evidence-based healthcare Collaborating Agency (NECA) has been the sole government-funded Health Technology Assessment (HTA) institution in Korea, yet little effort has been made to systematically evaluate the influence of its products. In this study, we aimed to measure the impact of the HTA products of NECA on clinical and policy decisions by introducing a systematic framework.
We included HTA reports published from 2009 to 2015. Among the 141 research reports published during this period, there were 67 HTA reports. We gathered data on the influence by literature and news article search, review of administrative documents and directly listening to the decision makers. The influence was categorized into three decision types: changes in clinical guidelines, administrative decision on investment/disinvestment and healthcare policy making. Whether a research report was used directly in decision making, or followed by subsequent researches or round-table conference, was recorded to examine the knowledge transfer process.
In total, 67.2 percent of the included HTA reports were used to support clinical and policy decisions. Twenty-seven reports had influenced administrative decisions on investment/disinvestment. Ten provided evidence for new health policies or legislation. Eight were reflected in clinical guidelines. The impact of HTA reports published by NECA was more evident when the research was directly requested by decision-making bodies such as government institutions. Although most HTA reports were conducted in collaboration with clinicians, the use of results by clinicians was limited. Definitive results were more likely to be used, but reports with competing interests had fewer impacts.
HTA by NECA had impacts on the rational use of healthcare resources in Korea, and NECA has established its role as an intermediary between governmental decision-making bodies and clinicians. However, more continuous approaches rather than one-time HTA research are needed for HTA on controversial topics to have impacts on decision making.
Purely infinite labeled graph $C^{\ast }$ -algebras
JA A JEONG, EUN JI KANG, GI HYUN PARK
Journal: Ergodic Theory and Dynamical Systems / Volume 39 / Issue 8 / August 2019
Published online by Cambridge University Press: 04 December 2017, pp. 2128-2158
In this paper, we consider pure infiniteness of generalized Cuntz–Krieger algebras associated to labeled spaces $(E,{\mathcal{L}},{\mathcal{E}})$ . It is shown that a $C^{\ast }$ -algebra $C^{\ast }(E,{\mathcal{L}},{\mathcal{E}})$ is purely infinite in the sense that every non-zero hereditary subalgebra contains an infinite projection (we call this property (IH)) if $(E,{\mathcal{L}},{\mathcal{E}})$ is disagreeable and every vertex connects to a loop. We also prove that under the condition analogous to (K) for usual graphs, $C^{\ast }(E,{\mathcal{L}},{\mathcal{E}})=C^{\ast }(p_{A},s_{a})$ is purely infinite in the sense of Kirchberg and Rørdam if and only if every generating projection $p_{A}$ , $A\in {\mathcal{E}}$ , is properly infinite, and also if and only if every quotient of $C^{\ast }(E,{\mathcal{L}},{\mathcal{E}})$ has property (IH).
Do we always need gelfoam packing in the middle ear cavity during tympanoplasty?: Presenting Author: Woo Jin Kim
Woo Jin Kim, Ji Sun Kong, Jamil AL-Swiahb, So Young Park, Chang Yeong Jeong, Dong Kee Kim, Sang Won Yeo, Shi Nae Park
Journal: The Journal of Laryngology & Otology / Volume 130 / Issue S3 / May 2016
Published online by Cambridge University Press: 03 June 2016, p. S191
Association between personality traits and mental health outcomes in older adults with lifetime trauma exposure: a nationwide community sample
Jee Eun Park, Hye Won Suk, Su Jeong Seong, Ji Hoon Sohn, Bong-Jin Hahm, Dong-Woo Lee, Maeng Je Cho
Journal: International Psychogeriatrics / Volume 28 / Issue 9 / September 2016
Published online by Cambridge University Press: 05 February 2016, pp. 1533-1543
This study evaluated the impacts of earlier traumatic events on the mental health of older adults, in terms of mental disorders and mental well-being, according to sociodemographic variables, trauma-related characteristics, and personality traits in a nationally representative sample of older Koreans.
A total of 1,621 subjects aged 60 to 74 years from a Korean national epidemiological survey of mental disorders responded face-to-face interviews. The Korean Composite International Diagnostic Interview was used to investigate lifetime trauma exposure (LTE) and psychiatric diagnoses. The EuroQol health classification system and life satisfaction scale were used to assess quality of life (QoL), and the Big Five Inventory-10 (BFI-10) to measure personality traits.
Five-hundred and seventy-seven subjects (35.6%) reported a history of LTE (mean age at trauma, 30.8 years old). Current mental disorders were more prevalent in elderly people with LTE, while better current QoL was more frequent in those without LTE. Among older people with LTE, lower extraversion and higher neuroticism increased the risk of current mood or anxiety disorders, whereas higher extraversion increased the probability of experiencing mental well-being after adjusting for sociodemographic and trauma-related variables.
Personality traits, especially extraversion, and neuroticism, may be useful for predicting the mental health outcomes of LTE in older adults. Further longitudinal studies investigating the relationship between traumatic events and mental health outcomes are needed.
EARLY ASSESSMENT AND PREDICTION OF POTENTIAL IMPACT OF THE IMPLANTATION OF POLYURETHANE SCAFFOLD IN PARTIAL MENISCAL LESIONS: A PILOT HORIZON SCANNING ACTIVITY IN SOUTH KOREA
Ji Yun Tark, Ji-young Jeong, Min Lee, Eunjung Park, Jooyeon Park, Ji Jeong Park, Sungkyu Lee, Chaemin Shin
Journal: International Journal of Technology Assessment in Health Care / Volume 31 / Issue 6 / 2015
Published online by Cambridge University Press: 18 December 2015, pp. 380-389
Objectives: The aim of this study was to predict the potential impact of the introduction of implantation of polyurethane scaffold for the treatment of partial meniscal lesions in the South Korean healthcare system.
Methods: The horizon scanning process was used to select a target technology and assess its potential impacts on patients and the Korean healthcare system. We identified and filtered research-phase health technologies that are not listed yet in Korean, but appear promising. After a process of prioritization, we chose the implantation of polyurethane scaffolds as a target technology. Then, through the procedures of assessment and peer review, we analyzed current evidence and its predicted potential impacts.
Results: There were eight studies included in the review: one prospective cohort and seven case-series studies. Six revealed significant improvements in function and pain relief. Of the six studies, which reported safety endpoints, four stated no major postoperative complications related to scaffold, and two reported adverse events and serious adverse events such as pain, joint swelling, et cetera. We also included the potential impact of this technology based on the experts' consultation. They all agreed that it would satisfy the diverse needs of patients and fulfill clinical needs. However, the majority of related clinical studies were based on short-term follow-up observations without any validation process involving comparison with control groups.
Conclusions: Through a horizon scanning activity, we found that the implantation of polyurethane scaffolds is a promising technology to resolve articular cartilage defects; however, long-term evidence with comparison groups for safety and effectiveness is required.
Periventricular white matter hyperintensities and the risk of dementia: a CREDOS study
Sangha Kim, Seong Hye Choi, Young Min Lee, Min Ji Kim, Young Don Kim, Jin Young Kim, Jin Hong Park, Woojae Myung, Hae Ri Na, Hyun Jeong Han, Yong S. Shim, Jong Hun Kim, Soo Jin Yoon, Sang Yun Kim, Doh Kwan Kim
Journal: International Psychogeriatrics / Volume 27 / Issue 12 / December 2015
Cerebral white matter hyperintensities (WMH) are prevalent incident findings on brain MRI scans among elderly people and have been consistently implicated in cognitive dysfunction. However, differential roles of WMH by region in cognitive function are still unclear. The aim of this study was to ascertain the differential role of regional WMH in predicting progression from mild cognitive impairment (MCI) to different subtypes of dementia.
Participants were recruited from the Clinical Research Center for Dementia of South Korea (CREDOS) study. A total of 622 participants with MCI diagnoses at baseline and follow-up evaluations were included for the analysis. Initial MRI scans were rated for WMH on a visual rating scale developed for the CREDOS. Differential effects of regional WMH in predicting incident dementia were evaluated using the Cox proportional hazards model.
Of the 622 participants with MCI at baseline, 139 patients (22.3%) converted to all-cause dementia over a median of 14.3 (range 6.0–36.5) months. Severe periventricular WMH (PWMH) predicted incident all-cause dementia (Hazard ratio (HR) 2.22; 95% confidence interval (CI) 1.43–3.43) and Alzheimer's disease (AD) (HR 1.86; 95% CI 1.12–3.07). Subcortical vascular dementia (SVD) was predicted by both PWMH (HR 16.14; 95% CI 1.97–132.06) and DWMH (HR 8.77; 95% CI 1.77–43.49) in more severe form (≥ 10 mm).
WMH differentially predict dementia by region and severity. Our findings suggest that PWMH may play an independent role in the pathogenesis of dementia, especially in AD.
Knock-in fibroblasts and transgenic blastocysts for expression of human FGF2 in the bovine β-casein gene locus using CRISPR/Cas9 nuclease-mediated homologous recombination
Young-Hee Jeong, Yeong Ji Kim, Eun Young Kim, Se Eun Kim, Jiwoo Kim, Min Jee Park, Hong-Gu Lee, Se Pill Park, Man-Jong Kang
Journal: Zygote / Volume 24 / Issue 3 / June 2016
Many transgenic domestic animals have been developed to produce therapeutic proteins in the mammary gland, and this approach is one of the most important methods for agricultural and biomedical applications. However, expression and secretion of a protein varies because transgenes are integrated at random sites in the genome. In addition, distal enhancers are very important for transcriptional gene regulation and tissue-specific gene expression. Development of a vector system regulated accurately in the genome is needed to improve production of therapeutic proteins. The objective of this study was to develop a knock-in system for expression of human fibroblast growth factor 2 (FGF2) in the bovine β-casein gene locus. The F2A sequence was fused to the human FGF2 gene and inserted into exon 3 of the β-casein gene. We detected expression of human FGF2 mRNA in the HC11 mouse mammary epithelial cells by RT-PCR and human FGF2 protein in the culture media using western blot analysis when the knock-in vector was introduced. We transfected the knock-in vector into bovine ear fibroblasts and produced knock-in fibroblasts using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system. Moreover, the CRISPR/Cas9 system was more efficient than conventional methods. In addition, we produced knock-in blastocysts by somatic cell nuclear transfer using the knock-in fibroblasts. Our knock-in fibroblasts may help to create cloned embryos for development of transgenic dairy cattle expressing human FGF2 protein in the mammary gland via the expression system of the bovine β-casein gene.
Effects of social supports on burden in caregivers of people with dementia
Ji Won Han, Hyeon Jeong, Jae Young Park, Tae Hui Kim, Dong Young Lee, Dong Woo Lee, Seung-Ho Ryu, Shin-Kyeom Kim, Jong Chul Yoon, JinHyeong Jhoo, Jeong Lan Kim, Seok Bum Lee, Jung Jae Lee, Kyung Phil Kwak, Bong-Jo Kim, Joon Hyuk Park, Ki Woong Kim
Journal: International Psychogeriatrics / Volume 26 / Issue 10 / October 2014
Social support programs for dementia caregivers were widely used in order to reduce care burden. We investigated which types of social supports can reduce psychological and non-psychological burdens of dementia caregivers, and explored the mechanism of those social supports.
We evaluated 731 community-dwelling dementia patients and their caregivers from the National Survey of Dementia Care in South Korea. We investigated the five types of social supports (emotional support, informational support, tangible support, positive social interaction, affectionate support) using the Medical Outcomes Study Social Support Survey in each caregiver. The mechanisms of specific types of social support on psychological/non-psychological burden were examined using path analysis.
Positive social interaction and affectionate support reduced psychological burden via direct and indirect paths. Tangible support reduced the non-psychological burden via direct and indirect paths. Informational support and emotional support were not helpful for reducing psychological or non-psychological burden. A maximum of 20% of psychological burden could be relieved by positive social interaction and 10.3% of that could be reduced by affectionate support. Tangible support was associated with a 15.1% maximal improvement in non-psychological burden.
In order to reduce caregiver burden in dementia effectively, psychosocial interventions should be tailored to target type of caregiver burden.
Contralesional Spasticity of Conjugate Gaze in Striatocapsular Infarction
Jin-Woo Park, Jeong-Yoon Choi, Jin-Man Jung, Do-Young Kwon, Moon Ho Park, Ji-Soo Kim
Journal: Canadian Journal of Neurological Sciences / Volume 41 / Issue 2 / March 2014
A 44-year-old man developed sudden non-fluent aphasia and right hemiplegia due to left striatocapsular infarction (Figure). Neurologic examination revealed gaze deviation to the right with eyes closed, but not with eyes open (Video). There was no spontaneous or gaze-evoked nystagmus, even after elimination of visual fixation. Leftward pursuit was impaired in a craniotopic frame of reference, and horizontal saccades were hypometric in both directions. Head impulse test was normal in the horizontal plane and there were no visual field defects. The contralesional gaze deviation with eye closure persisted for ten days.
Role of severity and gender in the association between late-life depression and all-cause mortality
Hyun-Ghang Jeong, Jung Jae Lee, Seok Bum Lee, Joon Hyuk Park, Yoonseok Huh, Ji Won Han, Tae Hui Kim, Ho Jun Chin, Ki Woong Kim
Journal: International Psychogeriatrics / Volume 25 / Issue 4 / April 2013
Background: Mortality associated with depression may be influenced by severity of depression and gender. We investigated the differential impacts on all-cause mortality of late-life depression by the type of depression (major depressive disorder, MDD; minor depressive disorder, MnDD; subsyndromal depression, SSD) and gender after adjusting comorbid conditions in the randomly sampled elderly.
Methods: One thousand community-dwelling elderly individuals were enrolled. Standardized face-to-face clinical interviews, neurological examination, and physical examination were conducted to diagnose depressive disorders and comorbid cognitive disorders. Depressive disorders were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria and SSD to study-specific operational criteria. Five-year survivals were compared between groups using Cox proportional hazards models.
Results: By the end of 2010, 174 subjects (17.4%) died. Depressive disorder (p = 0.001) and its interaction term with gender (p < 0.001) were significant in predicting five-year survival. MDD was an independent risk factor for mortality in men (hazard ratio = 3.65, 95% confidence interval = 1.67–7.96) whereas MnDD and SSD were not when other risk factors were adjusted.
Conclusions: MDD may directly confer the risk of mortality in elderly men whereas non-major depression may be just an indicator of increased mortality in both genders.
Epidemiology and Clinical Features of Community-Onset Acinetobacter baumannii Infections
Seung Ji Kang, Cheol-In Kang, So Yeon Park, Young Eun Ha, Eun-Jeong Joo, Doo Ryeon Chung, Kyong Ran Peck, Nam Yong Lee, Jae-Hoon Song
Journal: Infection Control & Hospital Epidemiology / Volume 33 / Issue 10 / October 2012
Interactive influences of demographics on the Mini-Mental State Examination (MMSE) and the demographics-adjusted norms for MMSE in elderly Koreans
Jeong Lan Kim, Joon Hyuk Park, Bong Jo Kim, Moon Doo Kim, Shin-Kyum Kim, Yeon Kyung Chi, Tae Hui Kim, Seok Woo Moon, Moon Ho Park, Jae Nam Bae, Jong Inn Woo, Seung-Ho Ryu, Jong Chul Yoon, Nam-Jin Lee, Dong Young Lee, Dong Woo Lee, Seok Bum Lee, Jung Jae Lee, Chang-Uk Lee, Sung Man Chang, Ji Won Han, Jin Hyeong Jhoo, Changsu Han, Maeng Je Cho, Ki Woong Kim
Background: The influences of demographics, culture, language, and environmental changes on Mini-Mental State Examination (MMSE) scores are considerable.
Methods: Using a sample of 7452 healthy, community-dwelling elderly Koreans, aged 55 to 94 years, who participated in the four ongoing geriatric cohorts in Korea, we investigated demographic influences on MMSE scores and derived normative data for this population. Geropsychiatrists strictly excluded subjects with cognitive disorders according to the protocol of the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (CERAD-K) Clinical Assessment Battery (CERAD-K-C).
Results: Education (standardized β = 0.463), age (standardized β = −0.303), and gender (standardized β = −0.057) had significant effects on MMSE scores (p < 0.001). The score of MMSE increase 0.379 point per 1-year education, decrease 0.188 per 1-year older, and decrease 0.491 in women compared to men. Education explained 30.4% of the scores' total variance, which was much larger than the variances explained by age (8.4%) or gender (0.3%). Accordingly, we present normative data for the MMSE stratified by education (0, 1–3, 4–6, 7–9, 10–12, and ≥ 13 years), age (60–69, 70–79, and 80–89 years), and gender.
Conclusions: We provide contemporary education-, age-, and gender-stratified norms for the MMSE, derived from a large, community-dwelling elderly Korean population sample, which could be useful in evaluating individual MMSE scores.
Reliable semi-transparent pentacene thin-film transistors with polymer gate dielectric layers cured at an optimum temperature
Do Kyung Hwang, Ji Hoon Park, Jeong Min Choi, Jiyoul Lee, Seong Hun Jeong, Eugene Kim, Jae Hoon Kim, Seongil Im
Published online by Cambridge University Press: 26 February 2011, 0905-DD05-15
We report on the insulator-charging-effects of poly-4-vinylphenol (PVP) gate dielectric on the reliabilities of pentacene thin-film transistors (TFTs). Our PVP films were prepared by spin coating and curing at various temperatures (155, 175, and 200 °C). Evaluated using Au/PVP/p +−Si structures, the dielectric strength of PVP films cured at 175 °C was superior to those of the other PVP films cured at different temperatures. Although saturation current and field mobility (∼0.13 cm2/Vs) obtained from a TFT with PVP film cured at 200 °C appeared higher than those (∼0.07 cm2/Vs) from the device with 175 °C-cured polymer film, the TFT prepared at 200 °C revealed a low on/off current ratio of less than 104 due to its high off-state current and also unreliable saturation behavior under repetitive gate voltage sweep. The unreliable behavior is due to the dielectric-charging caused by gate-electron-injection. We thus conclude that there are some optimal PVP-curing conditions to improve the reliability of pentacene TFT.
Activation of the Occipital Cortex and Deactivation of the Default Mode Network During Working Memory in the Early Blind
Hae-Jeong Park, Ji-Won Chun, Bumhee Park, Haeil Park, Joong Il Kim, Jong Doo Lee, Jae-Jin Kim
Journal: Journal of the International Neuropsychological Society / Volume 17 / Issue 3 / May 2011
Although blind people heavily depend on working memory to manage daily life without visual information, it is not clear yet whether their working memory processing involves functional reorganization of the memory-related cortical network. To explore functional reorganization of the cortical network that supports various types of working memory processes in the early blind, we investigated activation differences between 2-back tasks and 0-back tasks using fMRI in 10 congenitally blind subjects and 10 sighted subjects. We used three types of stimulus sequences: words for a verbal task, pitches for a non-verbal task, and sound locations for a spatial task. When compared to the sighted, the blind showed additional activations in the occipital lobe for all types of stimulus sequences for working memory and more significant deactivation in the posterior cingulate cortex of the default mode network. The blind had increased effective connectivity from the default mode network to the left parieto-frontal network and from the occipital cortex to the right parieto-frontal network during the 2-back tasks than the 0-back tasks. These findings suggest not only cortical plasticity of the occipital cortex but also reorganization of the cortical network for the executive control of working memory. (JINS, 2011, 17, 407–422)
Spiral Photonic Actuator
Jin Kwang-Yong, Park Seul-Ki, Jang Ji-Hyun, Cheongyang Koh, Mattew J Graham, Park Soo-Jin, Nah Changwoon, Lee Myung-Hoon, Stephen Z. D. Cheng, Edwin Thomas, Jeong Kwang-Un
Published online by Cambridge University Press: 31 January 2011, 1190-NN03-11
There has been a significant effort to create spiral sensors by changing either the periodic d-spacing of the structure or the dielectric constants of the materials by combining the multi-faceted environmental responsiveness of polymer hydrogels with dielectrical structures.1 Reversible spiral switches with dimensional functionalities that respond to chemical environment were constructed. When the spiral photonic actuator was swollen in hydrophilic acetic acid, right-handed spiral structures are formed, while the spiral photonic actuator was swollen in hydrophobic hexane, left-handed spiral structures are formed. All actuators returned back to the transparent planar state after deswelling processes. These reversible spiral photonic actuators can be applied in the application of mechanical actuators, electrical devices, and optical components.
Evaluative processing of ambivalent stimuli in patients with schizophrenia and depression: A [15O] H2O PET study
JAE-JIN KIM, HAE-JEONG PARK, YOUNG-CHUL JUNG, JI WON CHUN, HYE SUN KIM, JEONG HO SEOK, NAM WOOK KIM, IL HO PARK, MAENG-GUN OH, JONG DOO LEE
Journal: Journal of the International Neuropsychological Society / Volume 15 / Issue 6 / November 2009
Published online by Cambridge University Press: 01 November 2009, pp. 990-1001
Decision making in an emotionally conflicting situation is important in social life. We aimed to address the similarity and disparity of neural correlates involved in processing ambivalent stimuli in patients with schizophrenia and patients with depression. Behavioral task-related hemodynamic responses were measured using [15O]H2O positron emission tomography (PET) in 12 patients with schizophrenia and 12 patients with depression. The task was a modified word-stem completion task, which was designed to evoke ambivalence in forced and non-forced choice conditions. The prefrontal cortex and the cerebellum were found to show increased activity in the healthy control group. In the schizophrenia group, activity in these two regions was negligible. In the depression group, the pattern of activity was altered and a functional compensatory recruitment of the inferior parietal regions was suggested. The prefrontal cortex seems to be associated with the cognitive control to resolve the conflict toward the ambivalent stimuli, whereas the cerebellum reflects the sustained working memory to search for compromise alternatives. The deficit of cerebellar activation in the schizophrenia group might underlie the inability to search and consider compromising responses for conflict resolution. (JINS, 2009, 15, 990–1001.)
Low-temperature growth and characterization of epitaxial ZnO nanorods by metalorganic chemical vapor deposition
Dong Chan Kim, Bo Hyun Kong, Sung-Yun Jeon, Ji-Beom Yoo, Hyung Koun Cho, Dong Jun Park, Jeong Yong Lee
Journal: Journal of Materials Research / Volume 22 / Issue 7 / July 2007
By injecting additional argon gas, we were able to grow one-dimensional ZnO nanorod arrays with a uniform distribution on a large scale at a low temperature of less than 330 °C by metalorganic chemical vapor deposition. All of the nanorods grown on the sapphire substrate had a 30° in-plane rotation with respect to the substrate and showed the epitaxial characteristics of [10¯10]ZnO//[11¯20]sapphire, despite the low-temperature growth. These ZnO nanorods with high crystalline quality exhibited a high enhancement factor and low turn-on field value, thus having good potential to be used as a field emitter.
Microstructural characterization of sputter-deposited Pt thin film electrode
Ji-Eun Lim, Jae Kyeong Jeong, Kun Ho Ahn, Hyeong Joon Kim, Cheol Seong Hwang, Dong-Yeon Park, Dong-Su Lee
Journal: Journal of Materials Research / Volume 19 / Issue 2 / February 2004
Pt thin films of various thicknesses (30 nm ∼ 200 nm) were deposited on Si wafers with SiO2, Ti, TiO2, or IrO2 buffer layers at various temperatures (room temperature ∼200 °C) by a direct current magnetron sputtering process. The Pt films showed a strong (111)-preferred texture irrespective of the thickness, under-layer, and growth temperature. The authors previously reported [J-E. Lim, D-Y. Park, J.K. Jeong, G. Darlinski, H.J. Kim, and C.S. Hwang, Appl. Phys. Lett. 81, 3224 (2002)] that the films were composed of three kinds of grains with slightly different (111) lattice parameters (bulklike, 1.0% and 2.1% larger). This study details the microstructural variations of the Pt films according to the variations of experimental parameters. The different deposition conditions produced slightly different crystalline structures, but the three different (111) lattice parameters were always found. Epitaxial (200) Pt films on a (200) MgO substrate and a highly (111) textured Au thin film on a SiO2/Si did not show the same splitting in the lattice parameter. The grains with 1.0% and 2.1% larger (111) lattice parameter almost disappeared after postannealing at 1000 °C. However, surface chemical binding of the Pt film before and after annealing was unchanged. Therefore, it is believed that the lattice parameter splitting in the (111) textured Pt film originated from the interfacial grains with the distorted crystal structure due probably to growth stress.