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91.
Shimizu H Nagasaki I Matsumura K Sayo N Saito T 《Accounts of chemical research》2007,40(12):1385-1393
Examples of developments in asymmetric hydrogenation from various perspectives, in an effort to improve efficiency, are reported. Discussed in this Account are (1) the improved synthesis of BINAP ligands, (2) the design of SEGPHOS ligands for higher enantioselectivity, (3) a new protocol with fewer reaction steps to synthesize beta-aminoesters, and (4) a novel asymmetric hydrogenation mediated by a copper catalyst. 相似文献
92.
In this paper, a new application of superconducting magnetic energy storage (SMES) for diagnosis of power systems is proposed. Basic experiments for measurement of damping coefficient of power systems by use of SMES are carried out in an experimental system with a small generator, artificial transmission lines, and a small SMES. The SMES produces small power disturbances in the power system without affecting its operating conditions. The small power oscillations in the power system due to continuous power disturbances generated by SMES are observed. The relations among the damping coefficient, the power disturbances, and the power change of SMES are discussed for a one-machine infinite-bus system. The damping coefficients of the power system are obtained by investigating the oscillations due to the sinusoidal power changes of the SMES. The possibility of estimation of the steady-state power system stability by monitoring the damping coefficients of an operating power system by the use of SMES can be shown experimentally. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 40–48, 1997 相似文献
93.
Takeshi Hagio Kazushige Yamauchi Takenori Kohama Toshiya Matsuzaki Kazuhiko Iwai 《Materials science & engineering. C, Materials for biological applications》2013,33(5):2967-2970
Beta tricalcium phosphate (β-TCP) is a resorbable bioceramic that has hitherto been utilized in the medical field. Since it crystallizes in the anisotropic hexagonal system, properties such as chemical and physical ones are expected to depend on its crystal axis direction and/or on its crystal plane (anisotropy). Control of crystal orientation is thus important when used in polycrystalline form. Meanwhile, application of a strong magnetic field has been found to be a promising technique to control crystal orientation of anisotropic shape or structured crystals. In this work, we attempted to fabricate β-TCP ceramics with controlled crystal orientation by applying an external magnetic field during the slip casting process and subsequently sintering them at 1050 °C, below the β–α transition temperature. Application of a vertical magnetic field increased intensities of planes perpendicular to c-plane on the top surface, while a horizontal one with simultaneous mechanical mold rotation decreased it. These results indicated that crystal orientation of β-TCP ceramics were successfully controlled by the external magnetic field and together that the magnetic susceptibility of β-TCP is χc⊥ > χc//. 相似文献
94.
Kazuhiko Misawa Isao Matsuda Naoyuki T. Hashimoto Roy Lang 《Journal of Modern Optics》2013,60(16-18):2685-2692
Abstract A new optical telecommunication method combining time and frequency domain multiplexing is proposed using phase-controlled femtosecond pulses. Each pulse in a pulse train can be used as a data packet with data bits in the frequency domain. We call the new principle ‘wave packet engineering’, which adjusts the amplitude and phase of the wave function in device materials arbitrarily by controlling the spectral phase of femtosecond pulses. The optical phase-to-amplitude converter is demonstrated with organic dye molecules, in which the phase information in the phase-modulated pulses can be demodulated into the luminescence intensity. The luminescence intensity from cyanine dye molecules is observed to be chirp dependent, and is explained quantum mechanically in terms of coherent population transfer. The design principle of the device using semiconductor coupled quantum nanostructures is also discussed in terms of wave packet engineering. 相似文献
95.
Eiji Obarsawa Zdenek Slanina Kazuhiko Honda Xiang Zhao 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(2):259-270
Abstract Stone-Wales rearrangement may be considered to consist of two contiguous steps of olefin-carbene 1,2-C-C bond shift. Computational study on this mechanism led to high activation energies comparable to the bond dissociation energies of C-C bonds in fullerenes and their precursors. the possibility of passing through triplet transition state is denied on computational grounds. 相似文献
96.
Kazuhiko Izawa Yuriko Uchida Kiyoshi Ohkubo Masayoshi Totsuka Hiroki Sono Kotaro Tonoike 《Journal of Nuclear Science and Technology》2013,50(11):1043-1047
The possibility of criticality of fuel debris in a form of uranium dioxide (UO2)–concrete mixture is evaluated by calculating the infinite multiplication factor (k ∞) for a study of criticality control on the fuel debris generated through the molten core concrete interaction in a severe accident of a light water reactor. The infinite multiplication factor can be greater than unity, which means that handling of the mixture is subject to criticality control. This paper shows that concrete provides efficient neutron moderation and points out the necessity of further investigations on the criticality of UO2–concrete system for actual handling of fuel debris. 相似文献
97.
A macroazoinitiator (MAI) containing a poly(ethylene oxide) (PEO) block was used with a methyl methacrylate monomer to prepare polymer particles in ethanol/H2O solutions. The effects of the monomer/MAI ratio (RMI) and H2O content in the solutions on the molecular weight, particle diameters, and chemical structure of the resulting polymer particles were investigated. The reaction mixtures showed three kinds of states, which were milky colloid solutions, macrogels and/or precipitations, and clear solutions. The colloid solutions were obtained in the solutions with an H2O content of about 50–90 vol % and a RMI of 20–400. In the colloid solutions, core–shell nanospheres consisting of PEO shells and poly(methyl methacrylate) (PMMA) cores were predominantly obtained. In the specific conditions close to the area of gel and/or precipitation formation, particles connected about 0.5–5 μm in length were obtained. Multiblock copolymers nanospheres tended to be obtained with lower RMIs, and PMMA‐PEO‐PMMA tri‐bloc and/or PMMA‐PEO di‐block copolymer nanospheres were obtained with higher RMIs. The solubility of the monomer and the generated polymer in solutions may have affected the polymerization development and the state of the products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
98.
Hidenori Yahiro Kunimasa Sagata Tetsuya Yamamoto Kazuhiko Saiki Makiko Asamoto Hiroyuki Yamaura 《Catalysis Letters》2008,124(3-4):233-237
Among the supported Cu–FeOx catalysts, Al2O3-supported Cu–FeOx catalyst exhibited the highest activity for WGS reaction. The enhancement of the catalytic activity by adding FeOx to Cu/Al2O3 could be interpreted by the two possibilities; one is the formation of highly dispersed Cu0 and the other is the participation of reduced FeOx in WGS reaction in the presence of Cu0. 相似文献
99.
100.
Ambipolar organic field effect transistors with heterojunction structures have been fabricated using a biphenyl-capped thiophene oligomer (BP2T) and a naphthalene derivative (GS1b) for p-type and n-type organic semiconductors, respectively. Asymmetric electrode structures with Au source and Al-Li drain resulted in better performances than that of a symmetric device due to improved electron injection by the low work-function drain metal. 相似文献