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排序方式: 共有409条查询结果,搜索用时 15 毫秒
71.
Electrical resistivity and thermopower of (La1−xSrx)MnO3 and (La1−xSrx)CoO3 at elevated temperatures
T. Ohtani K. Kuroda K. Matsugami D. Katoh 《Journal of the European Ceramic Society》2000,20(16):105-2726
Electrical resistivity and Seebeck (S) measurements were performed on (La1−xSrx)MnO3 (0.02x0.50) and (La1−xSrx)CoO3 (0x0.15) in air up to 1073 K. (La1−xSrx)MnO3 (x0.35) showed a metal-to-semiconductor transition; the transition temperature almost linearly increased from 250 to 390 K with increasing Sr content. The semiconductor phase above the transition temperature showed negative values of S. (La1−xSrx)CoO3 (0x0.10) showed a semiconductor-to-metal transition at 500 K. Dominant carriers were holes for the samples of x0.02 above room temperature. LaCoO3 showed large negative values of S below ca. 400 K, indicative of the electron conduction in the semiconductor phase. 相似文献
72.
Phase equilibria of Sn-In based micro-soldering alloys 总被引:1,自引:0,他引:1
I. Ohnuma Y. Cui X. J. Liu Y. Inohana S. Ishihara H. Ohtani R. Kainuma K. Ishida 《Journal of Electronic Materials》2000,29(10):1113-1121
The phase equilibria of Sn-In-X (X=Ag, Bi, Sb, Zn), the most basic information necessary for the development of Pb-free micro-soldering
alloys, were studied using the CALPHAD method. Thermodynamic analyses for describing the Gibbs energies of the constituent phases were made by optimizing the obtained
data on the experimental phase diagrams, and such data in the literature, including data on thermochemical properties. The
present results combined with the thermodynamic database which was recently developed by our group [I. Ohnuma et al., J. Electron. Mater. 28, 1164 (1999)] provide various information on phase equilibria such as liquidus and solidus surfaces, isothermal and vertical
section diagrams, mole fractions of the phase constitutions, etc., and thermodynamic properties such as activity, heat of
mixing, surface energy, viscosity, etc., in multi-component soldering alloy systems including the elements of Pb, Bi, Sn,
Sb, Cu, Ag, Zn, and In. Typical examples for the phase diagrams and thermodynamic properties of Sn-In-X ternary systems are
shown. The application of the database to the alloy design for Pb-free solders is also presented. 相似文献
73.
A seven-day immersion test using several solutions was conducted on stainless steel, Co-based alloy, and Ni–Ti alloy, which are used for stents and stent grafts. The quantitative data on the release of each metal ion and the correlation between metal ion release rate and pH were obtained. The quantities of Fe and Ni released from stainless steel gradually decreased with increasing solution pH (pH 2–7.5). For Co–Cr–Mo–Ni–Fe alloy, the quantity of Cr released steadily increased as pH decreased (pH ≤ 6) and reached nearly zero at pHs higher than 6 (pH 6–7.5). Co release was slightly affected by a variation in pH. The quantities of Ni and Ti released from Ni–Ti alloy markedly increased with decreasing pH (pH ≤ 4) and they leveled off from pH 4 (pH 4–7.5). Although the rapid increases were observed at approximately pH 2, the quantities were even higher than that of Co released from the Co–Cr–Mo and Co–Cr–Mo–Ni–Fe alloys. For further investigation of the rapid increase in the quantities of metals released at pH 2, an anodic polarization test was employed to study the passive and transpassive behaviours of Ni–Ti alloy. The critical current density for the passivation of Ni–Ti alloy markedly increased as pH decreased (pH ≤ 4) and was low (1.4 μA/cm2) at pH higher than 4 (pH 4–7.5). The potential at a current density of 10 μA/cm2, by contrast, markedly rose with decreasing pH (pH ≤ 2), and was 1.2 V from pH 2 (pH 2–7.5). 相似文献
74.
Fukuyama Y Yasuda N Kim J Murayama H Ohshima T Tanaka Y Kimura S Kamioka H Moritomo Y Toriumi K Tanaka H Kato K Ishikawa T Takata M 《The Review of scientific instruments》2008,79(4):045107
An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of +/-8.40 ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide. 相似文献
75.
Yutaka Kawahara Tomohiro Yamamoto Kiyoshi Yamamoto Yoshimitsu Ikeda Yukihiro Nishikawa 《Journal of Natural Fibers》2020,17(4):609-621
ABSTRACTInjection-molding was performed using ethylene–propylene copolymer as the matrix by varying the physicochemical treatment of the reinforcement, i.e., core portion of kenaf stem that was dry-distilled and coated with or without β-sheet protein derivatives. Although dry distillation reduced the moisture content, the Charpy impact strength of the molded composites was low. When molding was performed using the fillers coated with β-sheet protein derivatives, especially coated with liquid silk (LS), a satisfactory Charpy impact strength of the molded composites was markedly gained. Thus, the β-sheet protein derivatives had potential to work as a compatibilizer. Coating the fillers with β-sheet proteins was also effective in suppressing the generation of silver streaks on the surface of composites and in preventing the occurrence of defective injection molding. 相似文献
76.
Synthesis of binary copper chalcogenides by mechanical alloying 总被引:2,自引:0,他引:2
Copper sulfides (tetragonal Cu1.92S-Cu1.99S, rhombohedral Cu1.71S-Cu1.89S, CuS), selenides (β Cu2 − xSe, Cu3Se2, γ CuSe, CuSe2), and tellurides (Cu2 − xTe, Cu3Te2) were prepared from mixtures of the elements by mechanical alloying (MA), using a high-energy ball mill. The compounds were obtained by 60–120 min of MA. It is notable that two metastable high-pressure phases were obtained by MA: tetragonal Cu2 − xS and pyrite-type CuSe2. The tetragonal phase gradually transformed to the stable phase of djurleite when kept at room temperature. Cu1.71S-Cu1.89S also formed a metastable rhombohedral phase. 相似文献
77.
A novel bacterial rhodopsin was identified in Haloarcula japonica strain TR-1. The gene encoding the bacterial rhodopsin was cloned and sequenced. The structural gene consisted of an open reading frame of 750 nucleotides encoding 250 amino acids. The deduced amino acid sequence of the Ha. japonica bacterial rhodopsin showed the highest homology to those of cruxrhodopsins. 相似文献
78.
J Yamamoto Y Shimamura H Nakahara Y Koishi M Kougo H Ohtani H Watanabe M Ishii M Ohmura 《Canadian Metallurgical Quarterly》1997,132(7):785-788
The leakage of pancreatic juice is the most serious complication after pancreatoduodenectomy. In an attempt to lessen the incidence of this complication, we have developed a simple technique for the anastomosis of pancreatogastrostomy. Since March 14, 1995, we have already performed surgical procedures on 8 cases of pancreatogastrostomy using this technique and as yet have never experienced fatal complications. We report the autopsy findings of pancreatogastric anastomosis histologically. The specimen taken from the anastomosis reveals good mucosal continuity. This result suggests the importance of reliable sutures between the pancreatic parenchyma and the full thickness of the gastric wall for the anastomosis of pancreatogastrostomy. 相似文献
79.
α-Tocopherol wss reacted with an alkylperoxyl radical at 37°C in ethanol. 2,2′-Azobis(2,4-dimethylvaleronitrile) was used to generate the alkylperoxyl radicals. The reaction products of α-tocopherol were isolated
by reverse-phase and normal-phase high performance liquid chromatography, and their structures were characterized by infrared,
ultraviolet,1H and13C nuclear magnetic resonances and mass spectrometry. They were 8aS-hydroperoxy-α-tocopherone, 8aR-hydroperoxy-α-tocopherone, a mixure of 7,8-epoxy-8aS-ethoxy-α-tocopherone, and 7,8-epoxy-8aR-ethoxy-α-tocopherone, 8aS-(1R-cyano-1,3-dimethyl)butylperoxy-α-tocopherone, 8aS-(1S-cyano-1,3-dimethyl)butylperoxy-α-tocopherone, a mixture of 8aR-(1S-cyano-1,3-dimethyl)butylperoxy-α-tocopherone and 8aR-(1S-cyano-1,3-dimethyl)butylperoxy-α-tocopherone, 4aR,5S-epoxy-8aS-ethoxy-α-tocopherone, 4aS,5R-epoxy-8aS-ethoxy-α-tocopherone and 4aR,5S-epoxy-8aR-ethoxy-α-tocopherone. 相似文献
80.
Huzo Kato Kohichi Ohtani Takehru Kohri Masahiro Morikura Masahiro Umehira Shuji Kubota 《International Journal of Satellite Communications and Networking》1988,6(3):289-300
Devices and architectures for on-board SCPC (single channel per carrier) multi-carrier demodulators suitable for use in satellites to be launched between the present and the year 2000 are discussed in the light of trends in the development of device technology towards lower on-board weight and power consumption. It is shown that at the present time (equivalent to about 1990 for on-board use). The choice of demodulation scheme depends on the number of channels available for regeneration on board the satellite. The total weight and power consumption for several suitable on-board multicarrier demodulation schemes are predicted for 1990, 1995 and 2000, as functions of the number of channels to be regenerated. 相似文献