text:
OSA Publishing > Optical Materials Express > Volume 8 > Issue 4 > Page 919
Alexandra Boltasseva, Editor-in-Chief
Compact refractive index sensor based on an S-tapered fiber probe
Chao Chen, Rui Yang, Xuan-yu Zhang, Wei-hua Wei, Qi Guo, Xing Zhang, Li Qin, Yong-qiang Ning, and Yong-sen Yu
Chao Chen,1,4 Rui Yang,2 Xuan-yu Zhang,3 Wei-hua Wei,3 Qi Guo,3 Xing Zhang,1 Li Qin,1 Yong-qiang Ning,1 and Yong-sen Yu3,5
1State Key Laboratory of Luminescence and Application, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
2Beijing Aerospace Yilian Science & Technology Development Co., Ltd, Beijing 100176, China
3State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China
4chenc@ciomp.ac.cn
5yuys@jlu.edu.cn
C Chen
R Yang
X Zhang
W Wei
Q Guo
L Qin
Y Ning
Y Yu
Vol. 8,
•https://doi.org/10.1364/OME.8.000919
Chao Chen, Rui Yang, Xuan-yu Zhang, Wei-hua Wei, Qi Guo, Xing Zhang, Li Qin, Yong-qiang Ning, and Yong-sen Yu, "Compact refractive index sensor based on an S-tapered fiber probe," Opt. Mater. Express 8, 919-925 (2018)
Serial-tilted-tapered fiber with high sensitivity for low refractive index range (OE)
Distributed refractive index sensing based on tapered fibers in optical frequency domain reflectometry (OE)
High sensitivity of taper-based Mach–Zehnder interferometer embedded in a thinned optical fiber for refractive index sensing (AO)
Fiber Bragg gratings
Long period gratings
Microstructured fibers
Fiber design and fabrication (060.2280)
Fiber optics (060.2310)
Fiber optics sensors (060.2370)
Revised Manuscript: February 11, 2018
Manuscript Accepted: February 12, 2018
2. Experimental methods
3. Results and discussions
We have demonstrated a refractive index (RI) sensor based on an S-tapered fiber probe (STFP) with a silver mirror on its end facet. The fiber probe has a compact size of about 1 mm, making it proper for sensing in narrow or limited space. The reflection spectra of the STFPs with different structure lengths have been analyzed and simulated. Its RI sensitivity in the range of 1.332 ~1.387 reaches 268.8 nm/RI unit, which is 9 times higher than that of the existing reflective fiber-taper-based RI sensor. Furthermore, the thermal response experimental results show that the STFP is temperature insensitive.
For decades, optical fiber sensors have attracted lots of interests in various physical, chemical and biological sensing applications due to their merits of small size, fast response, corrosion resistance, and biocompatibility [1–3]. Among them, fiber refractive index (RI) sensors have been intensively studied in recent years, because RI itself is an important physical parameter and many other biochemical parameters, such as solution concentration and pH value, can be measured based on RI change [4, 5]. To date, variety of fiber RI sensors have been developed, for example, fiber Bragg gratings (FBGs) [2, 6–8], long period fiber gratings (LPFGs) [3, 9], microstructured optical fibers (MOFs) [10–13], micro/nano fiber [14, 15], fiber-taper-based interferometers [16–22], and so on. The fiber-grating-based (FBGs and LPFGs) RI sensors have high resolution and a large detection range, but they require precise and expensive fabrication methods, including phase mask and laser source. The MOFs have high RI sensitivity, but the analytes need to be filled into the microholes of the fiber for each measurement, seriously complicating the test process. Micro/nanofiber sensor is also one of the best choices to realize highly sensitive RI measurement, which can achieve stronger evanescent field, but the mechanical strength and stability of the device will be reduced. The fiber-taper-based RI sensors in conventional optical fibers have advantages of simple structure, ease of fabrication and low cost, but their RI sensitivities are not satisfyingly high, and they usually have a large structure size with the total length of tens of millimeters, which is not compact for integrated applications. Recently, a novel RI sensor based on a single "S"-like fiber taper has been reported [21, 22]. The S fiber taper (SFT) sensor has a small size (less than 1 mm) and a high RI sensitivity. But its ultra-high axial strain sensitivity may affect the measurements when the structure has a small bending. In addition, like most of the fiber-taper-based Mach-Zehnder interferometers (MZIs) [16–18], the SFT works in the transmission mode, which is not flexible compared with the reflection-type sensors and limits its practical applications especially when the detection is required in some narrow or limited space, such as small-bore chemical containers or human blood vessels. However, the existing fiber-taper-based reflection-type RI sensors [19, 20] are too long to form a compact fiber probe.
In this paper, we propose a RI sensor based on the reflection-type S-tapered fiber probe (STFP), which has a silver mirror on the cleaved fiber end facet next to the SFT. The STFP has a short structure length of about 1 mm, which is more flexible in practical applications and is not easy to bend, avoiding the cross-sensitivity of structure bending. When the STFP has a proper structure length, its reflection dips and peaks will narrow down, improving the measurement accuracy. Its RI sensitivity in the low RI range of 1.332 ~1.387, which is more significant in chemical and biomedical sensing, reaches as high as 268.8 nm/RI unit (RIU), nine times higher than that of the fiber-taper-based Michelson interferometer RI sensor [19]. Moreover, the STFP is temperature-insensitive, making it a suitable candidate for temperature independent RI sensing.
The schematic diagram of the STFP is shown in Fig. 1 (a). It consists of an S fiber taper and a silver mirror on the end facet. We first fabricated the SFT on a standard telecom single-mode fiber (SMF-28e, Corning, Inc.) by using a fusion splicer (Ericsson FSU-975). The detailed fabrication method was described in ref [22]. In our experiment, the discharge current, tapering time and axial offset of the fiber holders were set as 10 mA, 9 s and 150 μm, respectively. The obtained SFT was 725 μm in length and 62.5 μm in waist diameter. The axial offset is 100 μm [Fig. 1(b), inset]. Its transmission spectrum is shown in Fig. 2(a). The deepest attenuation peak is located at 1545 nm with an extinction ratio (attenuation difference of maximum and minimum value) of over 10 dB. Later, the SFT was cleaved and the silver mirror was fabricated on its end face. The fiber cleaving process was conducted under a microscope with a graduated scale on it in order to guarantee the flatness of the fiber end face and precisely control the length of the S-tapered fiber end-tip. The silver mirror was fabricated with chemical plating method. After cleaving, the cleaved fiber was dipped into the stannous chloride solution for several seconds to sensitize the surface of the fiber. Then the Tollens' reagent was prepared with a test tube and the temperature was set about 40 °C with water bath. In the end, the fiber was dipped in the test tube for 3 ~5 mins. In this way, a silver mirror with thickness of hundereds of nanometers was deposited on its end facet to form a fiber probe, as shown in the inset figure of Fig. 1(b). The opaque region on the fiber probe is silver coating. The silver mirror is used not only for enhancing the reflection (reflectivity R~80%) but also to protect the fiber end facet from contamination. The STFP was connected to a reflection-type optical path for RI sensing, as shown in Fig. 1(b). Light from a supercontinuum broadband light source (BBS) (Superk Compact, NKT Photonics, Inc.) propagates through a circulator and goes into the STFP. Then the reflected light passes through the circulator again and is collected by an optical spectrum analyzer (OSA) (Yokogawa AQ6370B) to monitor and record the reflection spectrum change.
Fig. 1 (a) Schematic diagram of the STFP. (b) Experimental setup for RI sensing. Inset figure is the optical microscope image of the STFP.
Fig. 2 (a) Transmission spectrum of the SFT. (b), (c), (d) Reflection spectra of the STFPs with L of 10 mm, 375 μm, and 20 μm, respectively.
3.1 Spectral characteristics and numerical simulation
The reflection spectrum of the STFP is dependent on the length of L from the end of SFT to silver mirror, as shown in Fig. 1(a). The obtained reflection spectra of the STFPs with different L of 10 mm, 375 μm, and 20 μm are plotted in Fig. 2(b)-(d), respectively. The number of attenuation peaks reduces with L decreasing. Actually, the light interference occurs twice in the STFP, which is similar but different with the double-pass in-line fiber taper MZI [20]. In the case of double-pass fiber taper MZI, the second interference derived from the reflected light just considers the core mode because the fiber pigtail is long enough to attenuate the cladding mode energy. However, in the STFP, the reflected cladding mode must be considered to participate in the second light interference, because the reflected cladding mode cannot be ignored due to the short length of L. So the whole interference process in the STFP is divided into two steps. Firstly, the input light propagates through the SFT and the first interference occurs, which can be simply described as the two-wave interference form
(1)IT=I1+I2+2I1I2cos(ΔΦ)
where I1 and I2 are the light intensities of the core mode and the cladding mode, and ΔΦ is the phase difference between them. Here, ΔΦ=2πΔneffLeff/λ, where Δneff is the effective RI difference between the core and the cladding modes, Leff is the effective length of the SFT interferometer, and λ is the input light wavelength.
In the next step, the second interference of the reflected light occurs in the SFT and the output light intensity is expressed as a three-wave interference form
(2)IR=I1'+I2'+Icl+2I1'I2'cos(ΔΦ1)+2I1'Iclcos(ΔΦ2)+2I2'Iclcos(ΔΦ3)
where I1' and I2' are the light intensities of the core mode and the cladding mode in the SFT derived from the reflected core mode (R×IT), Icl is the light intensity of the reflected cladding mode, ΔΦ1, ΔΦ2, and ΔΦ3 are the phase differences between I1', I2' and Icl, respectively. We believe that just one dominant cladding mode needs to be considered in the interference. Therefore, the light intensities of I2' and Icl correspond to the same high-order cladding mode. Except for the amplitude, the main difference between them is that they have the different phase. So the phase differences aforementioned can be expressed as ΔΦ1=2πΔneffLeff/λ, ΔΦ2=2πΔneff(Leff+2L)/λ, ΔΦ3=0, respectively. ΔΦ1 has the same form as ΔΦ. For ΔΦ2, the cavity length of the interferometer is Leff+2L, in which 2L represents the light passing through the L section twice due to the silver mirror reflection and Leff represents the second interference in the SFT. Because the cladding modes of I2' and Icl have the same effective RI value, the effective RI difference between them is zero, resulting in ΔΦ3=0. The transmission spectrum of the SFT and the reflection spectra of the STFPs with different L were simulated based on the above formulas. As shown in Figs. 3(a)-(d), the computed spectra are consistent with the experimental results [Figs. 2(a)-(d)].
Fig. 3 (a) Computed transmission spectrum of the SFT. (b), (c), (d) Computed reflection spectra of the STFPs with L of 10 mm, 375 μm, 20 μm, respectively.
The reflection spectrum actually consists of a main and a secondary interferences. The main interference is dominantly controlled by the light intensities of I1' and I2', which are influenced by the geometrical parameters of the SFT and the silver mirror but are not affected by the length of L. The secondary interference is mainly influenced by the Icl and L. In the case of Fig. 2(b), the periodicity of the main interference is defined by the phase difference ΔΦ1. In addition, the relatively long L results in the dense resonance of the secondary interference. For Fig. 2(d), the L is so short that the phase difference of ΔΦ2 is nearly the same as ΔΦ1. So the secondary interference is negligible and the main periodicity of the interference is also determined by ΔΦ1, making the reflection dip and peak wavelengths of Figs. 2(b) and (d) are about the same.
When the length of L is shortening, the secondary interference peaks decrease and even disappear. So the relative short STFP has a simple reflection spectrum [Figs. 2(c) and (d)] and is good for sensor design. For Fig. 2(c), the narrow loss peaks used for sensing will enhance the measurement accuracy.
3.2 Sensing characteristics and discussions
The STFPs with L of 375 μm and 20 μm were chosen to test their RI responses at room temperature (20 °C). The STFPs were immersed in different concentrations of glycerin water solutions. The RI values of these solutions were calibrated by an Abbe refractometer at room temperature. We recorded the spectra change of attenuation peaks A and B [Figs. 2(c) and (d)] with different surrounding RI (SRI). The RI sensing results are shown in Fig. 4. Reflection spectra of the STFPs have a redshift with SRI increasing due to higher-order cladding mode, excited by the bending structure [21, 23], taking part in the light interference. Figures 4(b) and (d) show the wavelengths of peaks A and B change with SRI, respectively. The RI sensitivities in different RI ranges were also obtained. For peak A, in the RI ranges of 1.3320 ~1.4010, 1.4010 ~1.4146, and 1.4146 ~1.4216, the corresponding RI sensitivities are 158.7 nm/RIU, 323.5 nm/RIU, and 814.3 nm/RIU, respectively. The linearity is 0.993 through the linear fitting to the low RI range of 1.3320 ~1.4010. Its highest RI sensitivity is 1882.4 nm/RIU when the SRI changes between 1.4216 and1.4284. For peak B, in the RI range of 1.3320 ~1.3870, the RI sensitivity is 268.8 nm/RIU, which is 9 times higher than that of the reflective fiber-taper-based Michelson interferometer sensor [19], and the fitting linearity is 0.982. The other sensitivities are 562.1 nm/RIU, 908 nm/RIU, and 1760.3 nm/RIU in the RI ranges of 1.3870 ~1.4010, 1.4010 ~1.4216, and 1.4216 ~1.4284, respectively. The RI sensitivity augments with RI is owing to the cladding mode field expanding more energy to the environment with RI increasing, resulting in more sensitive response to SRI. Moreover, in order to improve the RI sensitivity of the sensor, we could minimize the waist diameter of the fiber to increase the evanescent field.
Fig. 4 (a) Reflection spectrum of the loss peak A changes with different SRI. (b) Relationship between the wavelength of peak A and SRI. (c) Reflection spectrum of the loss peak B changes with different SRI. (d) Relationship between the wavelength of peak B and SRI.
The thermal characteristic of the STFP is required and needs to be compensated in practical RI measurement, so we also investigated the temperature response of the STFP. The device was mounted on a hot plate, which was then heated up from room temperature to 100 °C in steps of 10 °C. The reflection spectrum of the STFP was nearly unchanged at different temperatures. The bottom wavelengths of loss peaks A and B just have random fluctuations with temperature, as shown in Fig. 5. Compared with the wavelength change with SRI, the temperature response of the STFP is negligible. This may be due to the combined effects of temperature induced RI change and thermal expansion induced axial strain variation in the SFT. The former drives the spectrum to move to longer wavelength but the latter pulls it back, making the two effects cancelled out. So the STFP is proper for the temperature independent RI sensing around room temperature.
Fig. 5 (a), (b) Wavelengths of peak A and peak B change with temperature, respectively.
In conclusion, we have fabricated an S-tapered fiber probe for highly sensitive RI measurement. The STFP consists of an SFT and a silver mirror on the end facet. Its total length is about 1 mm, making it proper for sensing in narrow and small area. The reflection spectrum of the STFP has been discussed and simulated, and it is dependent on the total length of the structure. RI and temperature sensing experiments have been carried out. The results show that the STFP is temperature insensitive and has a RI sensitivity of 268.8 nm/RIU in the linear RI range of 1.3320 ~1.3870. This sensitive, low cost and simple structured RI sensor will find applications in chemical and biological sensing fields.
National Key Research and Development Program of China (No. 2017YFB1104300); National Natural Science Foundation of China (Nos. 61505206, 61590930, 91423102, 91323301, and 61435005); Science and Technology Development Project of Jilin Province (No. 20180201014GX).
C. Chen and R. Yang contributed equally to this work.
1. B. H. Lee, Y. H. Kim, K. S. Park, J. B. Eom, M. J. Kim, B. S. Rho, and H. Y. Choi, "Interferometric fiber optic sensors," Sensors (Basel) 12(3), 2467–2486 (2012). [CrossRef] [PubMed]
2. A. Cusano, D. Paladino, and A. Iadicicco, "Microstructured fiber Bragg gratings," J. Lightwave Technol. 27(11), 1663–1697 (2009). [CrossRef]
3. S. W. James and R. P. Tatam, "Optical fibre long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14(5), R49–R61 (2003). [CrossRef]
4. P. Vaiano, B. Carotenuto, M. Pisco, A. Ricciardi, G. Quero, M. Consales, A. Crescitelli, E. Esposito, and A. Cusano, "Lab on fiber technology for biological sensing applications," Laser Photonics Rev. 10(6), 922–961 (2016). [CrossRef]
5. T. Guo, "Fiber grating-assisted surface plasmon resonance for biochemical and electrochemical sensing," J. Lightwave Technol. 35(16), 3323–3333 (2017). [CrossRef]
6. W. Liang, Y. Y. Huang, Y. Xu, R. K. Lee, and A. Yariv, "Highly sensitive fiber Bragg grating refractive index sensors," Appl. Phys. Lett. 86(15), 151122 (2005). [CrossRef]
7. C. Chen, Y. S. Yu, R. Yang, C. Wang, J. C. Guo, Y. Xue, Q. D. Chen, and H. B. Sun, "Reflective optical fiber sensors based on tilted fiber Bragg gratings fabricated with femtosecond laser," J. Lightwave Technol. 31(3), 455–460 (2013). [CrossRef]
8. T. Allsop, R. Arif, R. Neal, K. Kalli, V. Kundrát, A. Rozhin, P. Culverhouse, and D. J. Webb, "Photonic gas sensors exploiting directly the optical properties of hybrid carbon nanotube localized surface plasmon structures," Light Sci. Appl. 5(2), e16036 (2016). [CrossRef]
9. M. Śmietana, M. Koba, P. Mikulic, and W. J. Bock, "Towards refractive index sensitivity of long-period gratings at level of tens of µm per refractive index unit: fiber cladding etching and nano-coating deposition," Opt. Express 24(11), 11897–11904 (2016). [CrossRef] [PubMed]
10. O. Frazão, J. L. Santos, F. M. Araújo, and L. A. Ferreira, "Optical sensing with photonic crystal fibers," Laser Photonics Rev. 2(6), 449–459 (2008). [CrossRef]
11. D. K. Wu, B. T. Kuhlmey, and B. J. Eggleton, "Ultrasensitive photonic crystal fiber refractive index sensor," Opt. Lett. 34(3), 322–324 (2009). [CrossRef] [PubMed]
12. A. Schwuchow, M. Zobel, A. Csaki, K. Schröder, J. Kobelke, W. Fritzsche, and K. Schuster, "Monolayers of different metal nanoparticles in microstructured optical fibers with multiplex plasmonic properties," Opt. Mater. Express 2(8), 1050–1055 (2012). [CrossRef]
13. N. Zhang, G. Humbert, Z. Wu, K. Li, P. P. Shum, N. M. Y. Zhang, Y. Cui, J. L. Auguste, X. Q. Dinh, and L. Wei, "In-line optofluidic refractive index sensing in a side-channel photonic crystal fiber," Opt. Express 24(24), 27674–27682 (2016). [CrossRef] [PubMed]
14. J. Zhang, Q. Sun, R. Liang, J. Wo, D. Liu, and P. Shum, "Microfiber Fabry-Perot interferometer fabricated by taper-drawing technique and its application as a radio frequency interrogated refractive index sensor," Opt. Lett. 37(14), 2925–2927 (2012). [CrossRef] [PubMed]
15. Q. Sun, H. Luo, H. Luo, M. Lai, D. Liu, and L. Zhang, "Multimode microfiber interferometer for dual-parameters sensing assisted by Fresnel reflection," Opt. Express 23(10), 12777–12783 (2015). [CrossRef] [PubMed]
16. Z. Tian, S. S. H. Yam, J. Barnes, W. Bock, P. Greig, J. M. Fraser, H. P. Loock, and R. D. Oleschuk, "Refractive index sensing with Mach-Zehnder interferometer based on concatenating two single-mode fiber tapers," IEEE Photonics Technol. Lett. 20(8), 626–628 (2008). [CrossRef]
17. Y. Miao, X. Ma, J. Wu, B. Song, H. Zhang, K. Zhang, B. Liu, and J. Yao, "Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids," Opt. Lett. 40(16), 3905–3908 (2015). [CrossRef] [PubMed]
18. S. L. Fu, H. H. Dai, Q. G. Shi, and B. J. Peng, "A refractive index sensor based on the tapering theory," IEEE Sens. J. 16(4), 954–957 (2016). [CrossRef]
19. Z. Tian, S. S. H. Yam, and H. P. Loock, "Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber," Opt. Lett. 33(10), 1105–1107 (2008). [CrossRef] [PubMed]
20. Y. Li, L. Chen, E. Harris, and X. Bao, "Double-pass in-line fiber taper Mach-Zehnder interferometer sensor," IEEE Photonics Technol. Lett. 22(23), 1750–1752 (2010). [CrossRef]
21. R. Yang, Y. S. Yu, Y. Xue, C. Chen, Q. D. Chen, and H. B. Sun, "Single S-tapered fiber Mach-Zehnder interferometers," Opt. Lett. 36(23), 4482–4484 (2011). [CrossRef] [PubMed]
22. R. Yang, Y. S. Yu, C. Chen, Y. Xue, X. L. Zhang, J. C. Guo, C. Wang, F. Zhu, B. L. Zhang, Q. D. Chen, and H. B. Sun, "S-tapered fiber sensors for highly sensitive measurement of refractive index and axial strain," J. Lightwave Technol. 30(19), 3126–3132 (2012). [CrossRef]
23. H. F. Taylor, "Bending effects in optical fibers," J. Lightwave Technol. 2(5), 617–628 (1984). [CrossRef]
B. H. Lee, Y. H. Kim, K. S. Park, J. B. Eom, M. J. Kim, B. S. Rho, and H. Y. Choi, "Interferometric fiber optic sensors," Sensors (Basel) 12(3), 2467–2486 (2012).
A. Cusano, D. Paladino, and A. Iadicicco, "Microstructured fiber Bragg gratings," J. Lightwave Technol. 27(11), 1663–1697 (2009).
S. W. James and R. P. Tatam, "Optical fibre long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14(5), R49–R61 (2003).
P. Vaiano, B. Carotenuto, M. Pisco, A. Ricciardi, G. Quero, M. Consales, A. Crescitelli, E. Esposito, and A. Cusano, "Lab on fiber technology for biological sensing applications," Laser Photonics Rev. 10(6), 922–961 (2016).
T. Guo, "Fiber grating-assisted surface plasmon resonance for biochemical and electrochemical sensing," J. Lightwave Technol. 35(16), 3323–3333 (2017).
W. Liang, Y. Y. Huang, Y. Xu, R. K. Lee, and A. Yariv, "Highly sensitive fiber Bragg grating refractive index sensors," Appl. Phys. Lett. 86(15), 151122 (2005).
C. Chen, Y. S. Yu, R. Yang, C. Wang, J. C. Guo, Y. Xue, Q. D. Chen, and H. B. Sun, "Reflective optical fiber sensors based on tilted fiber Bragg gratings fabricated with femtosecond laser," J. Lightwave Technol. 31(3), 455–460 (2013).
T. Allsop, R. Arif, R. Neal, K. Kalli, V. Kundrát, A. Rozhin, P. Culverhouse, and D. J. Webb, "Photonic gas sensors exploiting directly the optical properties of hybrid carbon nanotube localized surface plasmon structures," Light Sci. Appl. 5(2), e16036 (2016).
M. Śmietana, M. Koba, P. Mikulic, and W. J. Bock, "Towards refractive index sensitivity of long-period gratings at level of tens of µm per refractive index unit: fiber cladding etching and nano-coating deposition," Opt. Express 24(11), 11897–11904 (2016).
O. Frazão, J. L. Santos, F. M. Araújo, and L. A. Ferreira, "Optical sensing with photonic crystal fibers," Laser Photonics Rev. 2(6), 449–459 (2008).
D. K. Wu, B. T. Kuhlmey, and B. J. Eggleton, "Ultrasensitive photonic crystal fiber refractive index sensor," Opt. Lett. 34(3), 322–324 (2009).
A. Schwuchow, M. Zobel, A. Csaki, K. Schröder, J. Kobelke, W. Fritzsche, and K. Schuster, "Monolayers of different metal nanoparticles in microstructured optical fibers with multiplex plasmonic properties," Opt. Mater. Express 2(8), 1050–1055 (2012).
N. Zhang, G. Humbert, Z. Wu, K. Li, P. P. Shum, N. M. Y. Zhang, Y. Cui, J. L. Auguste, X. Q. Dinh, and L. Wei, "In-line optofluidic refractive index sensing in a side-channel photonic crystal fiber," Opt. Express 24(24), 27674–27682 (2016).
J. Zhang, Q. Sun, R. Liang, J. Wo, D. Liu, and P. Shum, "Microfiber Fabry-Perot interferometer fabricated by taper-drawing technique and its application as a radio frequency interrogated refractive index sensor," Opt. Lett. 37(14), 2925–2927 (2012).
Q. Sun, H. Luo, H. Luo, M. Lai, D. Liu, and L. Zhang, "Multimode microfiber interferometer for dual-parameters sensing assisted by Fresnel reflection," Opt. Express 23(10), 12777–12783 (2015).
Z. Tian, S. S. H. Yam, J. Barnes, W. Bock, P. Greig, J. M. Fraser, H. P. Loock, and R. D. Oleschuk, "Refractive index sensing with Mach-Zehnder interferometer based on concatenating two single-mode fiber tapers," IEEE Photonics Technol. Lett. 20(8), 626–628 (2008).
Y. Miao, X. Ma, J. Wu, B. Song, H. Zhang, K. Zhang, B. Liu, and J. Yao, "Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids," Opt. Lett. 40(16), 3905–3908 (2015).
S. L. Fu, H. H. Dai, Q. G. Shi, and B. J. Peng, "A refractive index sensor based on the tapering theory," IEEE Sens. J. 16(4), 954–957 (2016).
Z. Tian, S. S. H. Yam, and H. P. Loock, "Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber," Opt. Lett. 33(10), 1105–1107 (2008).
Y. Li, L. Chen, E. Harris, and X. Bao, "Double-pass in-line fiber taper Mach-Zehnder interferometer sensor," IEEE Photonics Technol. Lett. 22(23), 1750–1752 (2010).
R. Yang, Y. S. Yu, Y. Xue, C. Chen, Q. D. Chen, and H. B. Sun, "Single S-tapered fiber Mach-Zehnder interferometers," Opt. Lett. 36(23), 4482–4484 (2011).
R. Yang, Y. S. Yu, C. Chen, Y. Xue, X. L. Zhang, J. C. Guo, C. Wang, F. Zhu, B. L. Zhang, Q. D. Chen, and H. B. Sun, "S-tapered fiber sensors for highly sensitive measurement of refractive index and axial strain," J. Lightwave Technol. 30(19), 3126–3132 (2012).
H. F. Taylor, "Bending effects in optical fibers," J. Lightwave Technol. 2(5), 617–628 (1984).
Allsop, T.
Araújo, F. M.
Arif, R.
Auguste, J. L.
Bao, X.
Barnes, J.
Bock, W.
Bock, W. J.
Carotenuto, B.
Chen, Q. D.
Choi, H. Y.
Consales, M.
Crescitelli, A.
Csaki, A.
Cui, Y.
Culverhouse, P.
Cusano, A.
Dai, H. H.
Dinh, X. Q.
Eom, J. B.
Esposito, E.
Ferreira, L. A.
Fraser, J. M.
Frazão, O.
Fritzsche, W.
Fu, S. L.
Greig, P.
Guo, J. C.
Guo, T.
Harris, E.
Huang, Y. Y.
Humbert, G.
Iadicicco, A.
James, S. W.
Kalli, K.
Kim, M. J.
Kim, Y. H.
Koba, M.
Kobelke, J.
Kuhlmey, B. T.
Kundrát, V.
Lai, M.
Lee, B. H.
Lee, R. K.
Li, K.
Liang, R.
Liu, B.
Liu, D.
Loock, H. P.
Luo, H.
Ma, X.
Miao, Y.
Mikulic, P.
Neal, R.
Oleschuk, R. D.
Paladino, D.
Park, K. S.
Peng, B. J.
Pisco, M.
Quero, G.
Rho, B. S.
Ricciardi, A.
Rozhin, A.
Santos, J. L.
Schröder, K.
Schuster, K.
Schwuchow, A.
Shi, Q. G.
Shum, P.
Shum, P. P.
Smietana, M.
Song, B.
Sun, H. B.
Tatam, R. P.
Taylor, H. F.
Vaiano, P.
Wang, C.
Webb, D. J.
Wei, L.
Wo, J.
Wu, D. K.
Wu, Z.
Xu, Y.
Xue, Y.
Yam, S. S. H.
Yang, R.
Yariv, A.
Yu, Y. S.
Zhang, B. L.
Zhang, K.
Zhang, N.
Zhang, N. M. Y.
Zhang, X. L.
Zhu, F.
Zobel, M.
IEEE Sens. J. (1)
Light Sci. Appl. (1)
Meas. Sci. Technol. (1)
Opt. Mater. Express (1)
Sensors (Basel) (1)
(1) I T = I 1 + I 2 + 2 I 1 I 2 cos ( Δ Φ )
(2) I R = I 1 ' + I 2 ' + I c l + 2 I 1 ' I 2 ' cos ( Δ Φ 1 ) + 2 I 1 ' I c l cos ( Δ Φ 2 ) + 2 I 2 ' I c l cos ( Δ Φ 3 )


text:
Using Signaling Pathways to Overcome Immune Tolerance to Tumors
Edgar G. Engleman1,2,*,
Joshua Brody1, and
Luis Soares2
1Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
2Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
↵*Corresponding author. E-mail: edengleman{at}stanford.edu
Vol. 2004, Issue 241, pp. pe28
DOI: 10.1126/stke.2412004pe28
Edgar G. Engleman
1Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.2Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
Joshua Brody
Luis Soares
The ability of tumors to evade the immune system is thought to result from the inability of T lymphocytes to recognize and respond to tumor antigens. This lack of T cell response may depend on a failure of dendritic cells to present antigen in the proper context so that T cells become tolerant to tumor antigens rather than primed to undergo an immune response. The inability of tumor-associated dendritic cells to effectively present antigen may in turn depend on inhibitory factors in the tumor milieu. Recent experiments suggest that the administration of toll-like receptor ligands stimulate dendritic cell activation and maturation and may thus help overcome T cell tolerance to tumor antigens. Whether or not such an approach is clinically feasible remains to be seen.
You are going to email the following Using Signaling Pathways to Overcome Immune Tolerance to Tumors
By Edgar G. Engleman, Joshua Brody, Luis Soares
Science's STKE 13 Jul 2004 : pe28

redpajama_set_name: RedPajamaCommonCrawl


text:
In der Liste der Kulturdenkmale in Bitterfeld-Wolfen sind alle Kulturdenkmale der Stadt Bitterfeld-Wolfen (Landkreis Anhalt-Bitterfeld) und ihrer Ortsteile aufgelistet. Grundlage ist das Denkmalverzeichnis des Landes Sachsen-Anhalt, das auf Basis des Denkmalschutzgesetzes des Landes Sachsen-Anhalt vom 21. Oktober 1991 durch das Landesamt für Denkmalpflege und Archäologie Sachsen-Anhalt erstellt und seither laufend ergänzt wurde (Stand: 31. Dezember 2020).

Kulturdenkmale nach Ortsteilen

Bitterfeld

|}

Bobbau

|}

Greppin

|}

Holzweißig

|}

Nord

|}

Reuden

|}

Rödgen

|}

Thalheim

|}

Wolfen

|}

Zschepkau

|}

Ehemalige Kulturdenkmale nach Ortsteilen
Die nachfolgenden Objekte waren ursprünglich ebenfalls denkmalgeschützt oder wurden in der Literatur als Kulturdenkmale geführt. Die Denkmale bestehen heute jedoch nicht mehr, ihre Unterschutzstellung wurde aufgehoben oder sie werden nicht mehr als Denkmale betrachtet.

Bitterfeld

|}

Greppin

|}

Holzweißig

|}

Wolfen

|}

Legende

Literatur
 Sabine Oszmer: Denkmalverzeichnis Sachsen-Anhalt, Band 13, Landkreis Bitterfeld. Michael Imhof Verlag, Petersberg 2004, ISBN 3-937251-53-7.

Quellen
 Kleine Anfrage und Antwort Olaf Meister (Bündnis 90/Die Grünen), Prof. Dr. Claudia Dalbert (Bündnis 90/Die Grünen), Kultusministerium 19. März 2015 Drucksache 6/3905 (KA 6/8670) Denkmalverzeichnis Sachsen-Anhalt

Weblinks

 Denkmalinformationssystem Sachsen-Anhalt

Einzelnachweise und Anmerkungen

Bitterfeld-Wolfen
!

redpajama_set_name: RedPajamaWikipedia


text:
China overtakes US as world's biggest movie box office in 2020
Movie-going remains strong in China but the American industry is feeling the effects of postponed releases and delayed production.
By Sabah Choudhry, news reporter
Monday 19 October 2020 13:00, UK
Image: Chinese cinemas have been bolstered by hit domestic films like Second World War drama The Eight Hundred
China has surpassed the US for movie ticket sales for the first time, making it the world's biggest film box office.
Sales have so far reached $1.98bn (£1.5bn) for 2020, exceeding the US total of $1.9bn, according to Asian film industry consultancy Artisan Gateway.
Analysts expect the gap to widen "considerably" by the end of the year, according to The Hollywood Reporter.
North America has traditionally led the way in dominating box office sales, but the COVID-19 pandemic appears to have accelerated the shift towards China - the world's most populous country.
The change is being attributed to cinemas in the country staying open - albeit at 75% seating capacity - and China's apparent success in containing the virus.
Its recent week-long National Day holiday also helped boost ticket sales.
Image: Several big Hollywood film releases have been delayed - including the latest Bond
Between October 1-8, the country's cinemas sold $568m (£430m) of tickets, according to latest data.
More on China
Chinese spy: Alerts about foreign interference in British politics will become more common, Priti Patel tells MPs
Beijing Winter Olympics: Tickets won't be sold to general public due to 'severe and complex' COVID-19 situation
China posts 8.1% growth for 2021 but a property downturn and its zero-COVID policy could add pressure
Local blockbuster My People, My Homeland, meanwhile, made $19.1m (£14m) this past weekend - with the romance raising its earnings to $360m (£272m) after almost three weeks.
China has also produced the world's biggest film of 2020 - Second World War drama The Eight Hundred - bringing in $460m (£348m) and counting.
Hollywood's biggest earner is Sony's Bad Boys for Life at $426.5m (£355m), with the US market continuing to be hit by studios pushing back releases and postponing production.
:: Subscribe to the Backstage podcast on Apple Podcasts, Google Podcasts, Spotify, Spreaker
Marvel's Black Widow and the latest James Bond film will now be released next year.
Producers of No Time To Die pushed the film back a second time to April 2021 "in order to be seen by a worldwide theatrical audience".
Some industry experts are also reportedly concerned that political turmoil between Washington and Beijing could damage Hollywood's long-term position in China - the single market where film sales are on the rise again.


text:
Nicholas Gaskill
Andrew W. Mellon Postdoctoral Fellow in the Humanities
American Literature and Visual Culture (19th–early 20th century)
Ph.D., University of North Carolina at Chapel Hill, 2006
Nicholas Gaskill studies nineteenth- and early-twentieth-century U.S. literature, philosophy, and visual culture. He's currently writing a book on U.S. literature and theories of color perception at the turn of the twentieth century. He is an editor of The Lure of Whitehead (U of Minnesota P, 2014) and the author of several articles on topics such as aesthetics, pragmatism, the poster craze of the 1890s, and turn-of-the-twentieth-century U.S. fiction.
Vibrant Environments: The Feel of Color from the White Whale to the Red Wheelbarrow
This book project situates the color terms and images of modern U.S. writers within the sweeping changes to the visual landscape wrought by synthetic dyes, vibrant color media, and psychological accounts of embodied color perception. Focusing on four sites—the landscape, the domestic interior, the city, and the schoolroom—it argues that turn-of-the-century discussions of color encompass a range of concerns about the bodily and often nonconscious ways in which we engage our surroundings, as well as with the social and artistic techniques for managing such interactions. Within this general framework, Gaskill demonstrates how writers as diverse as Charlotte Perkins Gilman, L. Frank Baum, and Gertrude Stein developed their literary styles in relation to the practices of observation, presentation, and description that emerged alongside modern color. As a result, Gaskill's study provides a revisionary account of American literary modernism, a cultural history of abstract color in art, and a theoretical model for relating text and image.


As nail art lovers, here at The Amazing Blog we know how a good manicure can give the final touch to every outfit. That is why we couldn't be more excited when we received the new Summer range of nail polishes by Roxanne Campbell.
We tried two of these vibrant colours: "Violets Are Blue", which is a pretty flashy blue and "Off to Jamaica" a warm and light orange tone. What we liked the most about the Summer collection was its variety: from more subtle colours to flamboyant and energetic tints. You can use these delightful colours to play and match with your bikini look and they will let you enjoy until the last ray of sun by the pool as they are highly long lasting.
Roxanne Campbell mixed her past experience in Fashion Weeks, Nail Art at 2012 Olympics and her knowledge of nail art techniques to create high-quality nail polishes inspired by seasonal fashion trends and with a glossy effect when dried.
We cannot wait to try the Winter's range but for now, uplift your outfit and get your favourite Summer colours here for £ 10 each.


text:
当前期刊: Current Opinion in Solid State & Materials Science Go to current issue 加入关注
Coupling in situ experiments and modeling – Opportunities for data fusion, machine learning, and discovery of emergent behavior
Curr. Opin. Solid State Mater. Sci. (IF 8.418) Pub Date : 2019-11-30
Michael D. Sangid
This paper reviews recent studies, that not only includes both experiments and modeling components, but celebrates a close coupling between these techniques, in order to provide insights into the plasticity and failure of polycrystalline metals. Examples are provided of studies across multiple-scales, including, but not limited to, density functional theory combined with atom probe tomography, molecular dynamics combined with in situ transmission electron miscopy, discrete dislocation dynamics combined with nanopillars experiments, crystal plasticity combined with digital image correlation, and crystal plasticity combined with in situ high energy X-ray diffraction. The close synergy between in situ experiments and modeling provides new opportunities for model calibration, verification, and validation, by providing direct means of comparison, thus removing aspects of epistemic uncertainty in the approach. Further, data fusion between in situ experimental and model-based data, along with data driven approaches, provides a paradigm shift for determining the emergent behavior of deformation and failure, which is the foundation that underpins the mechanical behavior of polycrystalline materials.
Designing and transforming yield-stress fluids
Arif Z. Nelson, Kenneth S. Schweizer, Brittany M. Rauzan, Ralph G. Nuzzo, Jan Vermant, Randy H. Ewoldt
We review progress in designing and transforming multi-functional yield-stress fluids and give a perspective on the current state of knowledge that supports each step in the design process. We focus mainly on the rheological properties that make yield-stress fluids so useful and the trade-offs which need to be considered when working with these materials. Thinking in terms of "design with" and "design of" yield-stress fluids motivates how we can organize our scientific understanding of this field. "Design with" involves identification of rheological property requirements independent of the chemical formulation, e.g. for 3D direct-write printing which needs to accommodate a wide range of chemistry and material structures. "Design of" includes microstructural considerations: conceptual models relating formulation to properties, quantitative models of formulation-structure-property relations, and chemical transformation strategies for converting effective yield-stress fluids to be more useful solid engineering materials. Future research directions are suggested at the intersection of chemistry, soft-matter physics, and material science in the context of our desire to design useful rheologically-complex functional materials.
Electrocatalytic/photocatalytic properties and aqueous media applications of 2D transition metal carbides (MXenes)
Alessandro Sinopoli, Zakarya Othman, Kashif Rasool, Khaled A. Mahmoud
Exploring new links between crystal plasticity models and high-energy X-ray diffraction microscopy
Paul A. Shade, William D. Musinski, Mark Obstalecki, Darren C. Pagan, Armand J. Beaudoin, Joel V. Bernier, Todd J. Turner
The advancement and transition of computational materials models requires corresponding developments in experimental methods to provide new phenomenological insights as well as quantification of model performance. In this article, we explore the natural links between crystal plasticity modeling and a suite of high-energy X-ray diffraction experimental techniques referred to as high-energy diffraction microscopy (HEDM). HEDM methods provide information such as the elastic strain state of individual grains and the distribution of crystallographic orientations. As a non-destructive characterization method, pairing HEDM with in situ mechanical testing enables tracking of material state evolution through quantitative measurements that may be directly compared to a simulation. We highlight some recent successes in this area and provide suggestions for future research.
Biomaterials for 4D stem cell culture.
Amber M Hilderbrand,Elisa M Ovadia,Matthew S Rehmann,Prathamesh M Kharkar,Chen Guo,April M Kloxin
Stem cells reside in complex three-dimensional (3D) environments within the body that change with time, promoting various cellular functions and processes such as migration and differentiation. These complex changes in the surrounding environment dictate cell fate yet, until recently, have been challenging to mimic within cell culture systems. Hydrogel-based biomaterials are well suited to mimic aspects of these in vivo environments, owing to their high water content, soft tissue-like elasticity, and often-tunable biochemical content. Further, hydrogels can be engineered to achieve changes in matrix properties over time to better mimic dynamic native microenvironments for probing and directing stem cell function and fate. This review will focus on techniques to form hydrogel-based biomaterials and modify their properties in time during cell culture using select addition reactions, cleavage reactions, or non-covalent interactions. Recent applications of these techniques for the culture of stem cells in four dimensions (i.e., in three dimensions with changes over time) also will be discussed for studying essential stem cell processes.
Antimicrobial peptides and induced membrane curvature: geometry, coordination chemistry, and molecular engineering.
Nathan W Schmidt,Gerard C L Wong
Short cationic, amphipathic antimicrobial peptides are multi-functional molecules that have roles in host defense as direct microbicides and modulators of the immune response. While a general mechanism of microbicidal activity involves the selective disruption and permeabilization of cell membranes, the relationships between peptide sequence and membrane activity are still under investigation. Here, we review the diverse functions that AMPs collectively have in host defense, and show that these functions can be multiplexed with a membrane mechanism of activity derived from the generation of negative Gaussian membrane curvature. As AMPs preferentially generate this curvature in model bacterial cell membranes, the selective generation of negative Gaussian curvature provides AMPs with a broad mechanism to target microbial membranes. The amino acid constraints placed on AMPs by the geometric requirement to induce negative Gaussian curvature are consistent with known AMP sequences. This 'saddle-splay curvature selection rule' is not strongly restrictive so AMPs have significant compositional freedom to multiplex membrane activity with other useful functions. The observation that certain proteins involved in cellular processes which require negative Gaussian curvature contain domains with similar motifs as AMPs, suggests this rule may be applicable to other curvature-generating proteins. Since our saddle-splay curvature design rule is based upon both a mechanism of activity and the existing motifs of natural AMPs, we believe it will assist the development of synthetic antimicrobials.
Polymeric Nanomedicines Based on Poly(lactide) and Poly(lactide-co-glycolide).
Rong Tong,Nathan P Gabrielson,Timothy M Fan,Jianjun Cheng
Small molecule chemotherapeutics often have undesired physiochemical and pharmacological properties, such as low solubility, severe side effect and narrow therapeutic index. To address these challenges, polymeric nanomedicine drug delivery technology has been routinely employed, in particular with the use of biodegradable and biocompatible polyesters, such as poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA). Here we review the development and use of PLA and PLGA for the delivery of chemotherapeutic agents in the forms of polymer-drug conjugates and nanoconjugates.
Nanocrystals for the parenteral delivery of poorly water-soluble drugs.
Bo Sun,Yoon Yeo
Nanocrystals have drawn increasing interest in pharmaceutical industry because of the ability to improve dissolution of poorly water-soluble drugs. Nanocrystals can be produced by top-down and bottom-up technologies and have been explored for a variety of therapeutic applications. Here we review the methods of nanocrystal production and parenteral applications of nanocrystals. We also discuss remaining challenges in the development of nanocrystal products.
Peptide Self-Assembly for Crafting Functional Biological Materials.
John B Matson,R Helen Zha,Samuel I Stupp
Self-assembling, peptide-based scaffolds are frontrunners in the search for biomaterials with widespread impact in regenerative medicine. The inherent biocompatibility and cell signaling capabilities of peptides, in combination with control of secondary structure, has led to the development of a broad range of functional materials with potential for many novel therapies. More recently, membranes formed through complexation of peptide nanostructures with natural biopolymers have led to the development of hierarchically-structured constructs with potentially far-reaching applications in biology and medicine. In this review, we highlight recent advances in peptide-based gels and membranes, including work from our group and others. Specifically, we discuss the application of peptide-based materials in the regeneration of bone and enamel, cartilage, and the central nervous system, as well as the transplantation of islets, wound-healing, cardiovascular therapies, and treatment of erectile dysfunction after prostatectomy.
Polymer physics of the cytoskeleton.
Qi Wen,Paul A Janmey
The cytoskeleton is generally visualized by light or electron microscopy as a meshwork of protein filaments that spans the space between the nuclear envelope and the plasma membrane. In most cell types, this meshwork is formed by a three dimensional composite network of actin filaments, microtubules (MT), and intermediate filaments (IF) together with the host of proteins that bind to the sides or ends of these linear polymers. Cytoskeletal binding proteins regulate filament length, crosslink filaments to each other, and apply forces to the filaments. One approach to modeling the mechanical properties of the cytoskeleton and of cell in general is to consider the elements of the cytoskeleton as polymers, using experimental methods and theoretical models developed for traditional polymers but modified for the much larger, stiffer, and fragile biopolymers comprising the cytoskeleton. The presence of motor proteins that move actin filaments and microtubules also creates a new class of active materials that are out of thermodynamic equilibrium, and unconstrained by limitations of the fluctuation-dissipation theorem. These active materials create rich opportunities for experimental design and theoretical developments. The degree to which the mechanics of live cells can usefully be modeled as highly complex polymer networks is by no means certain, and this article will discuss recent progress in quantitatively measuring cytoskeletal polymer systems and relating them to the properties of the cell.
Living scaffolds for neuroregeneration.
Laura A Struzyna,Kritika Katiyar,D Kacy Cullen
Neural tissue engineers are exploiting key mechanisms responsible for neural cell migration and axonal path finding during embryonic development to create living scaffolds for neuroregeneration following injury and disease. These mechanisms involve the combined use of haptotactic, chemotactic, and mechanical cues to direct cell movement and re-growth. Living scaffolds provide these cues through the use of cells engineered in a predefined architecture, generally in combination with biomaterial strategies. Although several hurdles exist in the implementation of living regenerative scaffolds, there are considerable therapeutic advantages to using living cells in conjunction with biomaterials. The leading contemporary living scaffolds for neurorepair are utilizing aligned glial cells and neuronal/axonal tracts to direct regenerating axons across damaged tissue to appropriate targets, and in some cases to directly replace the function of lost cells. Future advances in technology, including the use of exogenous stimulation and genetically engineered stem cells, will further the potential of living scaffolds and drive a new era of personalized medicine for neuroregeneration.
Integrating Concepts of Material Mechanics, Ligand Chemistry, Dimensionality and Degradation to Control Differentiation of Mesenchymal Stem Cells.
Matthew G Haugh,Sarah C Heilshorn
The role of substrate mechanics in guiding mesenchymal stem cell (MSC) fate has been the focus of much research over the last decade. More recently, the complex interplay between substrate mechanics and other material properties such as ligand chemistry and substrate degradability to regulate MSC differentiation has begun to be elucidated. Additionally, there are several changes in the presentation of these material properties as the dimensionality is altered from two- to three-dimensional substrates, which may fundamentally alter our understanding of substrate-induced mechanotransduction processes. In this review, an overview of recent findings that highlight the material properties that are important in guiding MSC fate decisions is presented, with a focus on underlining gaps in our existing knowledge and proposing potential directions for future research.
Controlling stem cell behavior with decellularized extracellular matrix scaffolds.
Gillie Agmon,Karen L Christman
Decellularized tissues have become a common regenerative medicine platform with multiple materials being researched in academic laboratories, tested in animal studies, and used clinically. Ideally, when a tissue is decellularized the native cell niche is maintained with many of the structural and biochemical cues that naturally interact with the cells of that particular tissue. This makes decellularized tissue materials an excellent platform for providing cells with the signals needed to initiate and maintain differentiation into tissue-specific lineages. The extracellular matrix (ECM) that remains after the decellularization process contains the components of a tissue specific microenvironment that is not possible to create synthetically. The ECM of each tissue has a different composition and structure and therefore has unique properties and potential for affecting cell behavior. This review describes the common methods for preparing decellularized tissue materials and the effects that decellularized materials from different tissues have on cell phenotype.
Materials approaches for modulating neural tissue responses to implanted microelectrodes through mechanical and biochemical means.
Salah Sommakia,Heui C Lee,Janak Gaire,Kevin J Otto
Implantable intracortical microelectrodes face an uphill struggle for widespread clinical use. Their potential for treating a wide range of traumatic and degenerative neural disease is hampered by their unreliability in chronic settings. A major factor in this decline in chronic performance is a reactive response of brain tissue, which aims to isolate the implanted device from the rest of the healthy tissue. In this review we present a discussion of materials approaches aimed at modulating the reactive tissue response through mechanical and biochemical means. Benefits and challenges associated with these approaches are analyzed, and the importance of multimodal solutions tested in emerging animal models are presented.
Advanced Materials for Neural Surface Electrodes.
Amelia A Schendel,Kevin W Eliceiri,Justin C Williams
Designing electrodes for neural interfacing applications requires deep consideration of a multitude of materials factors. These factors include, but are not limited to, the stiffness, biocompatibility, biostability, dielectric, and conductivity properties of the materials involved. The combination of materials properties chosen not only determines the ability of the device to perform its intended function, but also the extent to which the body reacts to the presence of the device after implantation. Advances in the field of materials science continue to yield new and improved materials with properties well-suited for neural applications. Although many of these materials have been well-established for non-biological applications, their use in medical devices is still relatively novel. The intention of this review is to outline new material advances for neural electrode arrays, in particular those that interface with the surface of the nervous tissue, as well as to propose future directions for neural surface electrode development.
New insights into nickel-free superelastic titanium alloys for biomedical applications
A. Ramezannejad, W. Xu, W.L. Xiao, K. Fox, D. Liang, M. Qian
Superelastic titanium (Ti) alloys are a group of unique functional metallic materials capable of recovering a substantial amount of mechanical strain thereby offering superior resilience. Such strain recovery is significantly greater than that exhibited by conventional elasticity and has been demonstrated to be clearly beneficial and necessary for a vast range of biomedical and dental applications. For example, the age-related physiological deterioration of bones signifies the necessity of employing superelastic implants. Currently, NiTi alloy remains to be the premier choice of superelastic alloys in the broad biomedical sector. However, recently reinforced views on the toxic, carcinogenic and allergenic properties of nickel have resulted in intensified concerns. This has encouraged the design and fabrication of Ni-free superelastic Ti alloys. In addition, enabled by additive manufacturing (AM) or 3D printing, hierarchical micro-architectured lattice meta-materials can exhibit exceptional superelasticity without undergoing phase transformations, upending the conventional perception and unlocking brand-new pathways to exploiting metal superelasticity. This article discusses recent developments in Ni-free superelastic Ti alloys and the determining factors affecting their superelastic recoverable strain. The importance of implant superelasticity relative to the elastic and "superelastic" properties of human bones is examined. Also discussed are the advances in Ni-free Ti-based superelastic alloy design and superelasticity-demanding medical and dental applications. The impact of the AM-enabled micro-architectural design on the development of superelastic structures or superelastic meta-materials is deliberated. Future research priorities are suggested.
Current state of the art on tailoring the MXene composition, structure, and surface chemistry
Per.O.Å. Persson, Johanna Rosen
MXenes constitute a family of two-dimensional transition metal carbides, carbonitrides and nitrides. Discovered in 2011, the number of MXenes has expanded significantly and more than 20 different MXenes have been synthesized, with many more predicted from theoretical calculations. MXenes constitute an exceptional family of materials based on their availability for elemental alloying and control of surface terminations, which enables synthesis of a range of structures and chemistries. Consequently, the MXenes exhibit an unparalleled potential for tuning of the materials properties for a wide range of applications. At present, MXenes have emerged with astonishing electronic, optical, plasmonic and thermoelectric properties. This has resulted in a global surge of research around a wide variety of applications, including but not limited to energy storage, carbon capture, electromagnetic interference shielding, reinforcement for composites, water filtering, sensors, and photo-, electro- and chemical catalysis etc. In this review, we present the available state of the art tailoring of the MXene properties owing to recent advances in structural ordering and tuning of surface terminations.
Nanocellulose-based films and their emerging applications
Zhiqiang Fang, Gaoyuan Hou, Chaoji Chen, Liangbing Hu
Extensive research has been directed towards the reinvention of paper for advanced applications. Nanocellulose-based films, a novel class of specialty paper primarily made of nanocellulose, demonstrate an ideal combination of sustainability and enhanced or novel properties. Enormous efforts have been devoted to enhancing these intrinsic properties and/or creating novel functions to expedite and expand the use of these materials in high-end fields such as touchscreen, solar cells, and nanogenerators. We review state-of-the-art advances in nanocellulose-based films and their utilization in several emerging and promising fields. We begin with an introduction of four types of nanocellulose-based films distinguished by their functional material loads (e.g., synthetic macromolecular polymers, 0D, 1D, and 2D nanomaterials), which involves their manufacturing techniques, structure design, properties, novel functions, and underlying principles. Additionally, we summarize the value-added applications of nanocellulose-based films in flexible electronics, energy converting or harvesting devices, and water treatment. Finally, we provide a critical viewpoint on the remaining challenges and future opportunities in this field.
Micro-scale fatigue mechanisms in metals: Insights gained from small-scale experiments and discrete dislocation dynamics simulations
Steven Lavenstein, Jaafar A. El-Awady
This review paper providing a comprehensive review of insights gained from cyclic loading discrete dislocation dynamics simulations and micro-scale fatigue experiments on dislocation structure evolution, size effects on fatigue life and fatigue strength, and crack initiation/propagation in metals.
Chemical effects on He bubble superlattice formation in high entropy alloys
R.W. Harrison, G. Greaves, H. Le, H. Bei, Y. Zhang, S.E. Donnelly
The probable formation mechanism of He bubble superlattices relies on long range anisotropic diffusion of self-interstitial atoms (SIAs). Here we study He ion irradiation of pure Ni and two equiatomic concentrated solid-solution alloys (CSAs) of FeNi and FeCrNiCo. It is expected from the significantly reduced diffusion of SIAs in CSAs, including high entropy alloys (HEAs), that long range anisotropic SIA migration cannot be active. We report the formation of a He bubble lattice in pure Ni, and for the first time in FeNi and FeCrNiCo systems under 30 keV He ion irradiation at room temperature. The ion dose and flux required to form a bubble superlattice increase with chemical complexity. Comparing to Ni, SIA clusters change directions more frequently due to anisotropic elementally-biased diffusion from the higher degree of chemical non-homogeneity in CSAs. Nevertheless, anisotropic 1-D diffusion of interstitial defects is possible in these complex alloys over incrementally longer time scales and irradiation doses. The sluggish diffusion, characteristic in CSAs, leads to smaller superlattice parameters and smaller bubble diameters. The chemical biased SIA diffusion and its effects on He evolution revealed here have important implications on understanding and improving radiation tolerance over a wide range of extreme conditions.
A review of corrosion inhibitors for rust preventative fluids
Zhenglin Tang
Corrosion of metals has been a widespread issue in industries for centuries. The use of corrosion inhibitors in rust preventative fluids are commonly employed to provide the temporary corrosion protection to metals. The aim of this review is to summarize the rust inhibition properties, inhibition mechanism, chemistry and development of corrosion inhibitors for rust preventative fluids. Some suggestions for further research on corrosion inhibitors have also been discussed.
Predicting damage production in monoatomic and multi-elemental targets using stopping and range of ions in matter code: Challenges and recommendations
William J. Weber, Yanwen Zhang
The computer code, Stopping and Range of Ions in Matter (SRIM), is widely used to describe energetic processes of ion-solid interactions; its predictive power relies on the accuracy of energy loss/transfer and collision processes being considered. While the SRIM code is commonly applied in radiation effects research to predict damage production and in the semiconductor industry to estimate ion range and dopant concentration profiles, two challenges exist that affect its use: (1) inconsistency in estimations of atomic displacements between full-cascade and quick (modified Kinchin–Pease) options and (2) overestimation of electronic stopping power for slow heavy ions in light targets (e.g., Be and Si) or in compound targets containing light elements (e.g., C, N and O in carbides, nitrides and oxides). Based on a literature review and our experimental investigations, we discuss the underlying reasons for the discrepancies, clarify the physical limitations of the SRIM predictions, and, more importantly, provide recommendations to address the two challenges.
Recent advances in the manipulation of circularly polarised light with cellulose nanocrystal films
S.N. Fernandes, L.F. Lopes, M.H. Godinho
Significant advances have been made to control the iridescence and the selective reflection of left circularly polarised (LCP) light, and transmission of right circularly polarised (RCP) light of solid films prepared from cellulose nanocrystals (CNCs). However the manipulation of the photonic properties of the CNCs films, which reflect both RCP and LCP light is less investigated. Solid films prepare from natural sources as CNCs have advantageous characteristics that are absent in other synthetic structures, such as wide availability and renewability. Here we review and compare recent research activity involving the production and characterization of photonic band gap structures resulting from an anisotropic layer inserted between two cholesteric layers with different helical pitches but the same handedness. We make connections between systems existing in Nature and synthetic ones with the hope of advancing in the production and manipulation of CNCs-based photonic structures.
Chemically-biased diffusion and segregation impede void growth in irradiated Ni-Fe alloys
Alexander Barashev, Yuri Osetsky, Hongbin Bei, Chenyang Lu, Lumin Wang, Yanwen Zhang
Recent irradiations of Ni-Fe concentrated solid solution alloys have demonstrated significant improvement of radiation performance. This improvement is attributed to redistribution of the alloying elements near sinks of point defects (voids, dislocations) due to chemically-biased atomic diffusion, where vacancies have preference to migrate via Fe atoms and interstitials via Ni atoms. In Ni-Fe, all sinks are enriched by Ni atoms, which strongly affects further interactions of radiation-produced mobile defects with voids and dislocations, hence void growth and dislocation climb. Ni-decorated sinks interact stronger with interstitial atoms than vacancies, which enhances dislocation loops growth. At the same time, Ni segregation creates Fe-enriched "channels" for vacancy migration out of the damage region to agglomerate in the outer regions, inaccessible to interstitial atoms. Strong effect of chemically-biased diffusion is supported by transmission electron microscope characterization and calls for special attention in designing alloys with desired properties through tuning defect mobilities.
Recent advances and an industrial perspective of cellulose nanocrystal functionalization through polymer grafting
Stephanie A. Kedzior, Justin O. Zoppe, Richard M. Berry, Emily D. Cranston
Cellulose nanocrystals (CNCs) are an emerging nanomaterial for applications ranging from coatings and construction to adhesives and biomedical devices. Owing to their high aspect ratio, stiffness, and reinforcing potential, CNCs have shown great promise to be used in polymer nanocomposites. However, due to their inherent hydrophilicity and compatibility with polar environments, the use of CNCs in hydrophobic polymer matrices or in organic solvent-based formulations has been limited. To overcome this incompatibility, many reports on grafting polymers onto the surface of CNCs have been published over the past ten years. This review describes the recent advances in CNC surface functionalization through polymer grafting, and comprehensively covers the existing work to date. Methods including polymer "grafting to" and "grafting from" are described in detail, using polymerization techniques such as free radical, ring opening, and controlled radical polymerization. Purification and characterization of polymer-grafted CNCs, the potential for upscaling these functionalization methods, and current perspectives from academic and industrial viewpoints are presented.
Diverse nanocelluloses prepared from TEMPO-oxidized wood cellulose fibers: Nanonetworks, nanofibers, and nanocrystals
Akira Isogai, Yaxin Zhou
Effect of electronic energy dissipation on strain relaxation in irradiated concentrated solid solution alloys
Neila Sellami, Aurélien Debelle, Mohammad W. Ullah, Hans M. Christen, Jong K. Keum, Hongbin Bei, Haizhou Xue, William J. Weber, Yanwen Zhang
The effect of energy deposition by energetic particles on Ni and two single-phase concentrated solid solution alloys (NiFe and NiCoCrFe) is investigated through combined experimental and modelling efforts. Damage evolution as a function of increasing ion fluence is monitored via elastic strain developed in the irradiated crystals. We show that damage produced from displacement collision cascades is sensitive to subsequent highly ionizing irradiation that the strain generated by elastic nuclear collisions undergoes partial relaxation upon high-energy irradiation. This finding indicates a change in the damage structure upon electronic energy deposition due to both predominant defect annealing and growth of small defect clusters. Strain relaxation, more pronounced in the alloys than in Ni, is ascribed to both higher thermal conductivity and weaker electron-phonon coupling in Ni.
Critical insights into the reinforcement potential of cellulose nanocrystals in polymer nanocomposites
Chuanwei Miao, Wadood Y. Hamad
Cellulose nanocrystals (CNCs) are highly polar, negatively-charged hydrophilic nanoparticles extracted from biomass through acid hydrolysis. They have high crystallinity and stiffness, as well as exceptional capability in reinforcing some polymer nanocomposites. While these remarkable improvements are limited to a certain class of polymers under strict conditions, CNCs can contribute to improving nanocomposite performance via other means, such as nucleating effect or cross-linking capacity. In this review, we offer critical insights into the reinforcing mechanism(s) of CNC-polymer nanocomposites and the factors that influence their performance. We aim to provide answers to the following questions: (1) how do CNCs contribute to nanocomposite reinforcement via percolation theory; (2) how to form a percolated CNC network in a CNC-polymer nanocomposite; (3) what are the factors affecting CNC performance and how do they work; and (4) how can we take advantage of CNC's attributes to create high-performance nanocomposites?
Overview of the synthesis of MXenes and other ultrathin 2D transition metal carbides and nitrides
Louisiane Verger, Chuan Xu, Varun Natu, Hui-Ming Cheng, Wencai Ren, Michel W. Barsoum
In 2011, a new family of two dimensional (2D) carbides, carbonitrides and nitrides – labeled MXenes – was discovered. Since then the number of papers on these materials has increased exponentially for several reasons amongst them: their hydrophilic nature, excellent electronic conductivities and ease of synthesizing large quantities in water. This unique combination of properties and ease of processing has positioned them as enabling materials for a large, and quite varied, host of applications from energy storage to electromagnetic shielding, transparent conductive electrodes, electrocatalysis, to name a few. Since the initial synthesis of Ti3C2 in hydrofluoric acid, many more compositions were discovered, and different synthesis pathways were explored. Most of the work done so far has been conducted on top-down synthesis where a layered parent compound is etched and then exfoliated. Three bottom-up synthesis methods, chemical vapor deposition, a template method and plasma enhanced pulsed laser deposition have been reported. The latter methods enable the synthesis of not only high-quality ultrathin 2D transition metal carbide and nitride films, but also those that could not be synthesized by selective etching. This article reviews and summarizes the most important breakthroughs in the synthesis of MXenes and high-quality ultrathin 2D transition metal carbide and nitride films.
Recent advances towards applications of molecular bottlebrushes and their conjugates
Sidong Tu, Chandan Kumar Choudhury, Igor Luzinov, Olga Kuksenok
We focus on the most recent developments towards synthesis, modeling, and applications of molecular bottlebrushes. Unique structural characteristics and properties of the bottlebrushes along with an ability to synthetically tailor their structure and functionality open up a number of emergent applications of these polymer systems. The conformation and resulting properties of molecular bottlebrushes and multi-component assemblies encompassing bottlebrushes can be regulated via chemical nature of the backbone and side moieties of bottlebrushes, variation of the distance between grafting points of the side groups, and the degree of polymerization of the side chains. Herein, we highlight the most recent progress in relating the structure of the bottlebrushes with their properties and focus on a number of diverse emerging applications involving bottlebrushes in solvents, melts, and bottlebrushes conjugated with surfaces, interfaces, linear chains, or biomacromolecules. Among such applications are drug delivery and sensing applications, electronic and photonic materials and materials with strain-adaptive stiffening, thermal stabilization and enhancement of activity of enzymes conjugated with copolymer bottlebrushes, and surface modification for biomedical applications.
Recent advances in MXenes: From fundamentals to applications
Mohammad Khazaei, Avanish Mishra, Natarajan S. Venkataramanan, Abhishek K. Singh, Seiji Yunoki
The family of MAX phases and their derivative MXenes are continuously growing in terms of both crystalline and composition varieties. In the last couple of years, several breakthroughs have been achieved that boosted the synthesis of novel MAX phases with ordered double transition metals and, consequently, the synthesis of novel MXenes with a higher chemical diversity and structural complexity, rarely seen in other families of two-dimensional (2D) materials. Considering the various elemental composition possibilities, surface functional tunability, various magnetic orders, and large spin–orbit coupling, MXenes can truly be considered as multifunctional materials that can be used to realize highly correlated phenomena. In addition, owing to their large surface area, hydrophilicity, adsorption ability, and high surface reactivity, MXenes have attracted attention for many applications, e.g., catalysts, ion batteries, gas storage media, and sensors. Given the fast progress of MXene-based science and technology, it is timely to update our current knowledge on various properties and possible applications. Since many theoretical predictions remain to be experimentally proven, here we mainly emphasize the physics and chemistry that can be observed in MXenes and discuss how these properties can be tuned or used for different applications.
Reconfigurable nanoscale soft materials
Zihao Ou, Ahyoung Kim, Wen Huang, Paul V. Braun, Xiuling Li, Qian Chen
We discuss recent research efforts towards understanding and implementing the physical rules needed to make materials—especially materials composed of nanoscale building blocks—that exhibit the defining characteristics of living systems: adaptive and evolving functional behavior. In particular, we highlight advancements in direct imaging and quantifying of kinetic pathways governing structural reconfiguration in model systems of colloidal nanoparticles as well as emerging opportunities brought by frontier efforts in synthesizing shape-shifting colloids and flexible electronics. Direct observation of kinetic "crossroads" in nanoparticle self-assembly and reconfiguration will offer insight into how these steps can be manipulated to design dynamic, potentially novel materials and devices. Moreover, these principles will not be limited to nanoparticles; when extended to building blocks like soft micelles and proteins, they have the potential to have a similar impact throughout the broader field of soft matter physics.
Thermodynamic costs of dynamic function in active soft matter
Yong Dou, Kiran Dhatt-Gauthier, Kyle J.M. Bishop
Living matter combines complex structures and dissipative processes to achieve dynamic functions that rely on material organization in space and time. In this Review, we discuss recent progress in creating synthetic material systems capable of four such functions–keeping time, powering motion, building structures, and making copies. Chemical oscillators coordinate the temporal activity of material assemblies; molecular motors and active colloids convert chemical energy into mechanical forces and motions; chemical activation of self-assembling components provides temporal control over dissipative structures; information-rich nanomaterials replicate their structures in exponential fashion. These and other dynamic functions cannot be achieved at thermodynamic equilibrium but instead require flows of energy and matter to create and maintain spatiotemporal order. Such systems are captured within the framework of stochastic thermodynamics, which describes the fluctuating thermodynamic quantities of driven systems. Even far from equilibrium, these quantities obey universal relations, which establish fundamental trade-offs between the rate of energy dissipation and performance metrics such as precision, efficiency, and speed. For each function considered, we present a simple kinetic model that offers general insights that inform the design and creation of dissipative material systems capable of dynamic functions. Overall, we aim to bridge experimental efforts in active soft matter and theoretical advances from stochastic thermodynamics to inform future research on material systems inspired by living matter.
Bioinspired structural color sensors based on responsive soft materials
Meng Qin, Mo Sun, Mutian Hua, Ximin He
Structural colors in nature have inspired the design of diverse photonic structures, which can interact with light via interference, diffraction or scattering. Among them, responsive soft material-involved photonic structures uniquely feature large volumetric changes upon external stimuli. The volumetric changes result in peak/valley shift of reflection spectra and perceptible color changes, providing responsive soft material-based structural color systems capability of serving as sensors for detecting chemical and biological analytes. Synthetic polymers and some natural materials are the most studied and utilized responsive soft materials for constructing structural color sensors, by tuning the thickness and morphology of formed films, or incorporating them into template structures, or their self-assembling. In this review article, structural colors in nature are firstly introduced, followed by discussing recent developments of promising responsive soft material-based structural color sensors, including the design of structural color sensors based on synthetic polymers and natural materials, as well as their applications for chemical sensing, biosensing, and multi-analyte sensing with sensor arrays. For specific sensing of chemicals and biomolecules, the sensing performance is evaluated in terms of detection range, sensitivity, response time, and selectivity. For multi-analyte sensing, cross-reactive structural sensor arrays based on simply a single soft material will be shown capable of discriminating various series of similar compounds. The future development of structural color sensors is also proposed and discussed.
Towards mimicking biological function with responsive surface-grafted polymer brushes
Jacinta C. Conrad, Megan L. Robertson
Integrating in situ TEM experiments and atomistic simulations for defect mechanics
Josh Kacher, Ting Zhu, Olivier Pierron, Douglas E. Spearot
With recent advances in computational modeling and in situ transmission electron microscopy (TEM) technologies, there have been increased efforts to apply these approaches to understand defect-based mechanisms dictating deformation mechanics. In situ TEM experiments and atomistic simulations each have their own unique limitations, including observable length and time scales and accessibility of information, motivating approaches that combine the two approaches. In this paper, we review recent studies that combine atomistic simulations and in situ TEM experiments to understand defect mechanisms associated with deformation of metals and alloys. In addition, we discuss ongoing developments in characterization and simulation capabilities that are expected to significantly advance the field of defect mechanics and allow greater integration between atomistic simulations and in situ TEM experiments.
Revisiting the effects of molybdenum and tungsten alloying on corrosion behavior of nickel-chromium alloys in aqueous corrosion
K. Lutton Cwalina, C.R. Demarest, A.Y. Gerard, J.R. Scully
Minor alloying additions such as molybdenum (Mo) have major effects on the localized corrosion resistance of corrosion resistant alloys containing chromium. However, progress in alloy development is mostly based upon empirical observations, where any mechanistic insights are largely relegated to the latter stages of localized corrosion (i.e., stabilization and propagation) that are more readily accessible experimentally. For instance, it is well understood that Mo and tungsten (W) affect repassivation of local active, as well as widespread transpassive, corrosion sites and Mo surface enrichment during corrosion is well-documented. In this paper, a comprehensive examination of the functions and mechanism by which selected Mo and W operate to improve the passivity and resistance to breakdown during the initial stages of localized corrosion of the most common Ni-based solid solution alloys is presented. It is shown that Mo and W exert considerable influence on many stages of corrosion, including both passivation and film breakdown, re-enforcing old and introducing more recent ideas in this comprehensive review of the current state of corrosion research on Ni-Cr-(Mo + W) alloys.
Recent advances in vacuum assisted self-assembly of cellulose nanocrystals
Zhaolu Wang, Na Li, Lu Zong, Jianming Zhang
Flexible strain sensors fabricated using carbon-based nanomaterials: A review
Tao Yan, Zhe Wang, Zhi-Juan Pan
Flexible strain sensors have experienced growing demand due to their several potential applications, such as personalized health monitoring, human motion detection, structural health monitoring, smart garments, and robots. Recently, several academic results have been reported concerning flexible and stretchable strain sensors. These reports indicate that the materials and design methods have an important influence on the performance of strain sensors. Carbon-based nanomaterials including carbon-based nanofibers, carbon nanotubes, graphene, and carbon black nanoparticles play a key role in the fabrication of flexible strain sensors with excellent properties. In terms of design, carbon-based nanomaterials are generally combined with polymers to maintain the flexibility and stability of a strain sensor. Various combined methods were successfully developed using different assembly structures of carbon-based nanomaterials in polymers, such as uniform mixing and ordered structures, including films, fibers, nanofiber membranes, yarns, foams, and fabrics. The working mechanisms of the flexible strain sensors, including changing the conductive network between overlapped nanomaterials, tunneling effect, and crack propagation, are also different compared with that of traditional semiconductor and metal sensors. The effects of the carbon-based nanomaterial structures in polymers on the strain sensing performance have been comprehensively studied and analyzed. The potential applications of flexible strain sensors and current challenges have been summarized and evaluated. This review provides some suggestions for further development of flexible and stretchable strain sensors with outstanding performance.
Crystallization of amorphous complex oxides: New geometries and new compositions via solid phase epitaxy
Paul G. Evans, Yajin Chen, Jack A. Tilka, Susan E. Babcock, Thomas F. Kuech
The crystallization of amorphous complex oxides via solid phase epitaxy enables a wide range of opportunities in the formation of oxide materials in new geometries and with previously inaccessible compositions. Emerging methods for controlling crystallization from the amorphous form arise from recent advances in the deposition of amorphous oxides, the formation and placement of crystalline seeds, and have built on an expanded understanding of the kinetics of nucleation and crystal growth. Key discoveries include methods for the creation of epitaxial layers in perovskite, spinel, and pyrochlore complex oxides. The creation of nanoscale homoepitaxial and heteroepitaxial seeds has the potential to enable new directions in the integration of complex oxides with semiconductors and in devices based on oxygen ion transport. Future opportunities include the creation of complex oxides in morphologies and compositions exhibiting electronic, thermal, and magnetic phenomena enabling a variety of applications.
Superior wear resistance of diamond and DLC coatings
Ali Erdemir, Jean Michel Martin
Emerging methods and opportunities in nanoscale materials characterization
Paul G. Evans
The emergence of powerful nanomaterials characterization techniques promises to underpin a new range of advances in materials research. There have been significant developments in the characterization of the phase, structure, composition, and dynamics of materials at the nanoscale. Articles in this issue report recent advances in three areas: atom probe tomography, x-ray nanobeam scattering and diffraction, and x-ray photon correlation spectroscopy. Each of these provides three-dimensional insight into hard materials in ways that have been previously unavailable. Taken together, these emerging methods have the potential to provide new tests for materials theory and computation and to extend significantly the range of questions that can be answered in materials research.
Atom probe tomography of nanoscale architectures in functional materials for electronic and photonic applications
Alexander S. Chang, Lincoln J. Lauhon
X-ray nanobeam diffraction imaging of materials
Tobias U. Schülli, Steven J. Leake
Dynamics in hard condensed matter probed by X-ray photon correlation spectroscopy: Present and beyond
Qingteng Zhang (张庆腾), Eric M. Dufresne, Alec R. Sandy
Insight into the spatial ordering and dynamics of structural heterogeneity in materials is at the heart of understanding their structure and function. X-ray photon correlation spectroscopy (XPCS) measures the dynamic structure factor S(Q,t) providing information on the spontaneous low-energy dynamics intrinsic to many materials. Combined with in situ and in operando capabilities, XPCS provides unique insight into a variety of scientific areas, including phase separation in binary alloys, aging in metallic glasses, surface dynamics during growth, domain wall dynamics in ferroic complex oxides and charge and spin density wave motion in quantum materials. This review summarizes some recent XPCS work in these areas and discusses scientific opportunities that will be made possible with the many-fold increase in coherent flux provided by the world-wide construction and commissioning of X-ray sources based on multi-bend achromat (MBA) storage ring (SR) lattices and high repetition rate free electron lasers (FELs).
Modeling tribocorrosion of passive metals – A review
Shoufan Cao, Stefano Mischler
Tribocorrosion is a material degradation phenomenon resulting from interactive effects between wear and corrosion. It is commonly found in engineering applications (e.g. biomedical implants and marine equipment) which involve relative motion of contacting metals in a corrosive environment. In this study, models describing tribocorrosion of passive metals in sliding contacts were reviewed. Different categories of models (two-body or three-body contact models, lubricated tribocorrosion model, empirical models, multi-degradation models) were found in the literature. Through the identification of relevant chemo-mechanical degradation mechanisms, robust analytical expressions accurately predicting the overall material loss in tribocorrosion have been developed. Numerical methods have been used to describe time dependent transitions in tribocorrosion. Possibilities and limits of the proposed models in the literature as well as future trends are discussed in this review.
Nanomechanical testing of third bodies
Richard R. Chromik, Yinyin Zhang
During wear, materials undergo chemical and mechanical changes that lead to the formation of what are known as 'third bodies'. Tribologists have long understood that third bodies have significant influence on the friction and wear performance of materials. However, the inhomogeneous nature of third bodies and how they form at the 'buried interface' of a sliding tribological contact has long made it difficult to fully characterize and study them. Recently, there have been significant advancements in nanomechanical testing such that researchers have begun to use these techniques to, for the first time, determine mechanical properties of third bodies. Coupling these measurements with high resolution electron microscopy and surface chemical analysis has finally given tribologists the ability to obtain the necessary data to understand and model third bodies and their connections to friction and wear. This review will present recent work on the topic of nanomechanical testing of third bodies while at the same time identifying the challenges and opportunities this research presents.
Current developments of nanoscale insight into corrosion protection by passive oxide films
Vincent Maurice, Philippe Marcus
Oxide passive films are a key for the durability of metals and alloys components as well as a central issue in corrosion science and engineering. Herein, we discuss current developments of the nanometer and sub-nanometer scale knowledge of the barrier properties and adsorption properties of passive oxide films brought by recent model experimental and theoretical investigations. The discussed aspects include (i) the chromium enrichment and its homogeneity at the nanoscale in passive films formed on Cr-bearing alloys such as stainless steel, (ii) the corrosion properties of grain boundaries in early intergranular corrosion before penetration and propagation in the grain boundary network, and (iii) the interaction of organic inhibitor molecules with incompletely passivated metallic surfaces. In all three cases, key issues are highlighted and future developments that we consider as most relevant are identified.
Recent progress of NiCo2O4-based anodes for high-performance lithium-ion batteries
Xiao Han, Xuan Gui, Ting-Feng Yi, Yanwei Li, Caibo Yue
On the existence and origin of sluggish diffusion in chemically disordered concentrated alloys
Yuri N. Osetsky, Laurent K. Béland, Alexander V. Barashev, Yanwen Zhang
Selective electron beam manufactured Ti-6Al-4V lattice structures for orthopedic implant applications: Current status and outstanding challenges
X.Z. Zhang, M. Leary, H.P. Tang, T. Song, M. Qian
Additively manufactured Ti-6Al-4V lattices display unique mechanical and biological properties by virtue of their engineered structure. These attributes enable the innovative design of patient-specific medical implants that (i) are conformal to the intended surgical geometry, (ii) mimic the mechanical properties of natural bone, and (iii) provide superior biological interaction to traditional implants. Selective electron beam melting (SEBM) is an established metal additive manufacturing (AM) process that has enabled the design and fabrication of a variety of novel intricate lattices for implant applications over the last 15 years. This article reviews the technical and clinical characteristics of SEBM Ti-6Al-4V lattices, including (i) the SEBM process and its capabilities, (ii) the structures of human bones with an exhaustive list of corresponding mechanical properties from literature, (iii) the mechanical properties of SEBM Ti-6Al-4V lattices of various designs and their shortcomings when compared to human bones, (iv) microstructural control of SEBM Ti-6Al-4V lattices for improved performance, (v) the lattice manufacturability and associated geometric errors, and (vi) clinical cases. Existing literature on the mechanical response of SEBM Ti-6Al-4V lattice structures is exhaustively evaluated for documentation quality using established theoretical models. This extensive data-set allows novel insights into the effect of lattice design on mechanical response that is not possible with the individual data; and provides a comprehensive database for those who are actively involved in patient-specific SEBM implant design. On this basis, outstanding challenges and research opportunities for SEBM Ti-6Al-4V lattices in the biomedical domain are identified and discussed.
Predicting whether a material is ductile or brittle
R.P. Thompson, W.J. Clegg
In this paper we discuss the various models that have been used to predict whether a material will tend to be ductile or brittle. The most widely used is the Pugh ratio, G/K , but we also examine the Cauchy pressure as defined by Pettifor, a combined criterion proposed by Niu, the Rice and Thomson model, the Rice model, and the Zhou-Carlsson-Thomson model. We argue that no simple model that works on the basis of simple relations of bulk polycrystalline properties can represent the failure mode of different materials, particularly where geometric effects occur, such as small sample sizes. Instead the processes of flow and fracture must be considered in detail for each material structure, in particular the effects of crystal structure on these processes.
Anisotropic organic glasses
Ankit Gujral, Lian Yu, M.D. Ediger
While the last decades have seen considerable efforts to control molecular packing in organic crystals, the idea of controlling packing in organic glasses is relatively unexplored. Glasses have many advantageous properties that crystals lack, such as macroscopic homogeneity and compositional flexibility, but packing in organic glasses is generally considered to be isotropic and highly disordered. Here we review and compare four areas of recent research activity showing control over anisotropic packing in organic glasses: (1) anisotropic glasses of low molecular weight organic semiconductors prepared by physical vapor deposition, (2) the use of mesogens to produce anisotropic glasses by cooling equilibrium liquid crystal phases, (3) the preparation of highly anisotropic glassy solids by vapor-depositing low molecular weight mesogens, and (4) anisotropic films of polymeric semiconductors prepared by spin-coating or solution casting. We delineate the connections between these areas with the hope of cross-fertilizing progress in the development of anisotropic glassy materials.
Decoding the glass genome
John C. Mauro
Glassy phases in organic semiconductors
Chad R. Snyder, Dean M. DeLongchamp
Feedstock powder processing research needs for additive manufacturing development
Iver E. Anderson, Emma M.H. White, Ryan Dehoff
Additive manufacturing (AM) promises to redesign traditional manufacturing by enabling the ultimate in agility for rapid component design changes in commercial products and for fabricating complex integrated parts. By significantly increasing quality and yield of metallic alloy powders, the pace for design, development, and deployment of the most promising AM approaches can be greatly accelerated, resulting in rapid commercialization of these advanced manufacturing methods. By successful completion of a critical suite of processing research tasks that are intended to greatly enhance gas atomized powder quality and the precision and efficiency of powder production, researchers can help promote continued rapid growth of AM. Other powder-based or spray-based advanced manufacturing methods could also benefit from these research outcomes, promoting the next wave of sustainable manufacturing technologies for conventional and advanced materials.
Stress corrosion crack initiation in Alloy 690 in high temperature water
Tyler Moss, Wenjun Kuang, Gary S Was
Initiation of stress corrosion cracks in Alloy 690 in high temperature water is a rare occurrence and depends on the method by which the sample is loaded. Only in dynamic straining experiments is crack initiation consistently observed. Stress relaxation in constant deflection tests, and lack of a means of rupturing the oxide film in constant load tests are the principle reasons for the difficulty of initiating cracks in these tests. These observations, combined with those from the much more susceptible Alloy 600 form the basis for a mechanism stress corrosion crack (SCC) initiation of Alloy 690. SCC initiation is proposed to occur in three stages: an oxidation stage in which a protective film of Cr2O3 is formed on the surface over grain boundaries, an incubation stage in which successive cycles of oxide film rupture and repair depletes the grain boundary of chromium, and a nucleation stage in which the chromium depleted grain boundary is no longer able to support growth of a protective chromium oxide layer, resulting in formation and rupture of oxides down the grain boundary. The mechanism is supported by the available literature on oxidation and crack initiation of Alloy 690 in hydrogenated primary water conditions.
Recent approaches to reduce aging phenomena in oxygen- and nitrogen-containing plasma polymer films: An overview
M. Vandenbossche, D. Hegemann
Plasma polymer films (PPFs) are well-known for their enhanced stability compared to conventional polymer coatings. However, PPFs tend to undergo aging in air or in aqueous environments due to oxidation, hydrophobic recovery, hydrolysis and dissolution of oligomeric fragments. Such aging mechanisms cause modifications of the PPFs that entail a change in surface properties. For example, PPF surfaces which are probed for protein adsorption or cell adhesion might therefore be substantially different from the initial PPF. It becomes thus necessary to understand the chemical reactions involved in the chemical modification (and/or degradation) of PPFs. Here, a summary of the most important aging mechanisms occurring in PPFs is given. More precisely, chemical reactions that can potentially occur in oxygen- and nitrogen-containing plasma polymer films when stored in air and in water were highlighted. On the basis of this understanding, recent strategies to reduce or delay aging mechanisms and/or to provide time-controlled degradable PPFs are discussed: the enhancement of the degree of cross-linking, the formation of a gradient structure in the PPF during plasma deposition, and the chemical post-plasma treatment to reduce the number of reactive sites. Finally, potential applications of such coatings will be considered.
Hydrogen embrittlement in compositionally complex FeNiCoCrMn FCC solid solution alloy
K.E. Nygren, K.M. Bertsch, S. Wang, H. Bei, A. Nagao, I.M. Robertson
Coupled electronic and atomic effects on defect evolution in silicon carbide under ion irradiation
Yanwen Zhang, Haizhou Xue, Eva Zarkadoula, Ritesh Sachan, Christopher Ostrouchov, Peng Liu, Xue-lin Wang, Shuo Zhang, Tie Shan Wang, William J. Weber


This course have been developed for those who are working with children and infants. It will be of particular interest to teachers, child minders, crèche assistants, playgroup personnel and anyone else who has a responsibility for their welfare whilst in your care. We cover everything you need to know so you can gain the paediatric first aid certificate. Our high-quality paediatric first aid courses will help you get your national paediatric first aid certificate, valid for three years, meet Ofsted's requirements for providing first aid for infants and young children, comply with an Ofsted inspection.