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21.
Polycrystalline CuGaTe2 with a chalcopyrite-type structure consolidated by hot-pressing is a potential candidate as a medium-temperature thermoelectric (TE) material. However, its high-temperature formation phases have rarely been reported to date. Here, we investigated the temperature-dependent formation phases and crystal structure at 300–800 K of hot-pressed CuGaTe2. From synchrotron x-ray diffraction data and crystal structure analysis of the heating and cooling processes, it was clarified that a certain amount of impurity phases, such as Te and CuTe, precipitated from the CuGaTe2 matrix when the temperature was increased (to 500–650 K). This is the temperature range where CuGaTe2 has been reported to show high TE performance. After CuGaTe2 was heated to 800 K, such impurity phases remained, even when cooled to room temperature. They also affected the tetragonal distortion and the x-coordinate of Te in the CuGaTe2 matrix, probably due to deficiencies of Cu and Te in the matrix. Our results reveal detailed information on the formation phases of CuGaTe2 at high temperature and thus provide insight for evaluation of its high-temperature stability and transport properties. 相似文献
22.
Kenji Uchida Masahiko Kawata Tao Yang Shigeo Goto Tomoyoshi Mishima Atsuko Niwa Jun Gotoh 《Journal of Electronic Materials》1999,28(3):246-251
We have examined how a growth interruption, caused by closing group-III sources, affects the crystalline quality of InGaN/GaN
quantum-well (QW) structures grown by metalorganic vapor phase epitaxy. The QW samples were characterized by their photoluminescence
(PL), and by atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy dispersive x-ray (EDX) microanalysis.
The PL peak wavelength was strongly dependent on the duration of the growth interruption and on the number of QW layers. AFM
measurements revealed that the size of the open hexagonally shaped pits in the QW structures increased dramatically as the
interruption duration was lengthened. Through TEM and EDX microanalysis, we found that the formation of these hexahedronal
pits, formed due to the growth interruption, causes a large fluctuation in the In composition, especially around the pits,
and the presence of such pits in an underlying QW layer strongly affects the In incorporation into the upper QW layers, leading
to significant growth-rate variation in an InGaN QW layer and red-shifting of the PL spectra when a multiple-QW structure
is grown. 相似文献
23.
Yoshihisa Maeyama Kazunori Kadota Akira Kitayama Yuichi Tozuka Mikio Yoshida Atsuko Shimosaka Yoshiyuki Shirakawa 《International Journal of Hydrogen Energy》2017,42(16):11501-11509
A hybrid simulation was carried out using discrete variational (DV) Xα molecular orbital and molecular dynamics methods to examine the storage of hydrogen in metal nanoparticles. The calculation load was light and therefore could be performed quickly on a generic personal computer. The simulation investigates the electronic states of hydrogen on Pd and Ti nanoparticles. The hydrogen dissociation behavior on the metal surface was reproduced, and the calculated bonding orbitals of Pd and hydrogen are consistent with other reports. The diffusion coefficient of hydrogen inside the metal displays the same temperature dependence as the theoretical results. This simplified calculation, which produces results in agreement with experimental/theoretical values, could lead to improved simulation methods for hydrogen storage materials. 相似文献
24.
Wazawa T Ishizuka-Katsura Y Nishikawa S Iwane AH Aoyama S 《Analytical chemistry》2006,78(8):2549-2556
The surface of solid glass supports for samples in optical microscopy and for biosensors needs to be protein-resistant. A coating of a poly(ethylene glycol) monomethyl ether (mPEG) on the surface of the glass is one promising method for preventing the nonspecific adsorption of proteins. In this study, we have developed a novel technique for achieving an optimal coverage of a glass surface with mPEG to prevent protein adhesion. A clean glass substrate previously treated with (3-aminopropyl)dimethylethoxysilane (APDMES) was treated sequentially with poly(acrylic acid) and subsequently a primary amine derivative of mPEG in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The resultant glass surface was demonstrated to be highly protein-resistant, and the adsorption of bovine serum albumin decreased to only a few percentage points of that on a glass surface treated with APDMES alone. Furthermore, to extend the present method, we also prepared a glass substrate on which biotinylated poly(ethylene glycol) was cografted with mPEG, and biotinylated myosin subfragment-1 (biotin-S1) was subsequently immobilized on this substrate by biotin/avidin chemistry. Actin filaments were observed to glide on the biotin-S1-coated glass surface in the presence of ATP, and thus, the method is capable of immobilizing the protein specifically without any loss in its biological function. 相似文献
25.
Atsuko SHINOHARA Takehisa MATSUKAWA Momoko CHIBA Toshio KUMASAKA Jun KOBAYASHI Kenji TAKAMORI Shozo ICHINOSE Kazuhito YOKOYAMA 《中国稀土学报(英文版)》2010,(Z1):507-509
Distribution of Sm and Ce in mice was investigated after inhalation exposure to their oxide particles of 5 μm diameter and 15 mg/m3.Sm and Ce were mainly distributed in lung,their concentrations decreased with passing time,and their concentrations in lung were correlated with exposure periods.Concentrations of Ce were lower than that of Sm in each point.Sm was also distributed in the other organs and bone but Ce was scarcely detected.These results suggest that the behaviors of Sm and Ce inhaled were different,although their chemical properties are similar. 相似文献
26.
27.
Yoshio Nosaka Masami Matsushita Junichi Nishino Atsuko Nosaka 《Science and Technology of Advanced Materials》2013,14(2):143-148
In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO2 powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated into two different sites of the bulk phase of TiO2. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO2 powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system. 相似文献
28.
We report the fabrication of polymer thin films with “in-depth” dye-dispersed structures using a vacuum spray method. Copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine [(t-Bu)4CuPc] and polycarbonate in chloroform solution were sprayed onto the substrate. The (t-Bu)4CuPc distribution was controlled precisely during thin film growth by varying its concentration in the solution. Uniform, bilayer, and gradient structures of (t-Bu)4CuPc dispersed in thin films were confirmed by high-angle annular dark field imaging on scanning transmission electron microscopy. The vacuum spray method has several advantages compared to the casting method, such as smaller dispersed dye-aggregates and lack of cavities due to air bubbles. 相似文献
29.
A comparative study of ethanol production by Issatchenkia orientalis strains under stress conditions 总被引:1,自引:0,他引:1
Isono N Hayakawa H Usami A Mishima T Hisamatsu M 《Journal of Bioscience and Bioengineering》2012,113(1):76-78
The ability of 13 strains of multi-stress-tolerant Issatchenkia orientalis yeast to produce ethanol was examined under different stress conditions, including conditions of elevated H2SO4 and Na2SO4 concentrations and increased heat. The MF-121 strain produced a significant amount of ethanol after the incubation in acidic media containing high concentrations of salt, e.g., 50 g/l Na2SO4 at pH 2.0, or at high temperatures, e.g., 43°C, when compared with other strains. 相似文献
30.