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61.
The structure and properties of a chiral nematic phase, which reflects one hand of circularly polarized light in a narrow region of wavelength, of fully acetylated (ethyl) cellulose [(acetyl) (ethyl) cellulose, AEC] in acrylic acid (AA) were studied in comparison with (ethyl) cellulose (EC). AEC mesophase formed right-handed chiral nematic structure while EC formed left-handed one. AEC mesophase showed higher birefringence and reflection intensity. The relationship between the reflection wavelength and the polymer concentration was negatively correlated for both AEC and EC mesophases. The relationship between the reflection wavelength and the molecular weight was also negative for AEC mesophase whereas positive for EC mesophase. AEC mesophase was solidified by photopolymerization of AA moiety. It was revealed that the optical properties of AEC mesophase could be preserved by photopolymerization, since the resulting solid material reflects selectively one hand of circularly polarized light. 相似文献
62.
63.
Among various divalent metal ions, calcium has been found to be adsorbed tightly onto carboxymethylated chitin. The adsorption was completed not only by induced carboxyl groups but also by the support of acetamide, as well as primary and secondary hydroxyl groups. Although the adsorption capacity for transition metal ions was enhanced appreciably by regeneration into fibrous form, only that of calcium ion, among alkali-earth metals, was at the same level as that of transition metals. Since little effect was shown on the adsorption of phenylalanine by the blocking of α-amino and α-carboxyl groups of L-Phe, and since D-Phe was so a little adsorbed, the chiral specific adsorption of phenylalanine might be supported by mediation of calcium ion and by the contribution of hydrophobicity of the β-phenyl group. 相似文献
64.
Masao Ichida Yumie Kiyohara Yasumitsu Miyata Hiromichi Kataura 《Journal of luminescence》2009,129(12):1794-1797
We have investigated third-order nonlinear optical properties of bundled and isolated semiconducting single-walled carbon nanotubes (SWNTs) by means of Z-scan method, pump-probe method, and two-beam time-resolved degenerate four-wave mixing (DFWM) method. The figures of merit Im χ(3)/α in both bundled and isolated SWNTs samples were found to be enhanced with increasing tube diameter. The measured Im χ(3)/α value in the bundled SWNTs was an order of magnitude smaller than that in the isolated SWNTs. Both population relaxation time T1 and phase-relaxation time T2 for bundled samples were smaller than those in the isolated samples. These experimental results can be explained by an increase in nonradiative recombination rate and phase-relaxation rate in the bundled sample. The phase-relaxation time T2 is considered to have a significant role in the enhancement of Im χ(3)/α. 相似文献
65.
Yasumitsu Matsuo Keiko Saito Hiroshi Kawashima Seiichiro Ikehata 《Solid State Communications》2004,130(6):411-414
We have fabricated a fuel cell based on a superprotonic conductor, a Tl3H(SO4)2 crystal, and have measured the electrical properties of this fuel cell. It is found that the open-circuit voltage in the fuel cell based on the Tl3H(SO4)2 crystal increases by supplying H2 fuel gas and typically becomes 0.83 V. Moreover, we have observed that the cell voltage decreases with increasing current density, as observed in fuel cells such as proton exchange membrane fuel cell, solid oxide fuel cell, etc. These results indicate that it is possible to use the Tl3H(SO4)2 crystal as the electrolyte of a solid acid fuel cell. In addition, we suggest that the selection of the electrode and the preparation of the very thin electrolyte are extremely important to achieve high-efficiency of power generation of this fuel cell. 相似文献
66.
Masao Ichida Satoshi Sakoda Yumie Kiyohara Singo Saito Yasumitsu Miyata Hiromichi Kataura Ken-ichi Mizuno Hiroaki Ando 《Journal of luminescence》2008,128(5-6):952-955
We have studied 1D exciton relaxation dynamics in semiconducting single-walled carbon nanotubes (SWNTs) by femtosecond pump–probe experiments. The time evolution of change in transmittance ΔT/T induced by photo-excitation varies depending on the tube diameter. The decay time decreases with a decrease in the tube diameter. Pressure measurements have been conducted to explore the relaxation mechanism. The deformation potential estimated from the pressure dependence of photoluminescence spectra increases with decreasing tube diameter. This means that the exciton–phonon interaction becomes stronger in the smaller diameter tubes. The diameter dependences of decay time and deformation potential suggest that the exciton–phonon interaction plays an important role in exciton nonradiative relaxation process in semiconducting SWNTs. 相似文献
67.
We establish a necessary and sufficient condition under which the Shapley value of ann-person game lies in the core. 相似文献
68.
Yasumitsu Tamura Joong-Hyup Kim Yasuyoshi Miki Hironori Hayashi Masazumi Ikeda 《Journal of heterocyclic chemistry》1975,12(3):481-483
New routes to the v-triazolo[1,5-a]pyridine and pyrazolo[1,5-a]pyridine ring systems are described. Treatment of the N-amine salts of 2-picolinealdehyde oxime or 2-pyridyl ketone oximes with polyphosphoric acid gave v-triazolo[1,5-a]pyridines in fair yields. Treatment of 2-picolyl ketones or their oximes with O-mesitylenesulfonylhydroxylamine produced directly pyrazolo-[1,5-a]pyridines. These reactions were extended to the quinoline cases. 相似文献
69.
Yasumitsu Miyazaki 《Optical and Quantum Electronics》1977,9(2):153-165
The excitation characteristics and spatial coherence of partially coherent optical waves in gradient fibres are demonstrated for incident light waves radiated from semiconductor lasers and light emitting diodes. Lower modes are efficiently excited in the case of coherent laser beams, while incident waves of low coherence such as lightwaves of LEDs excite higher modes. Pulse propagation of partially coherent optical waves in dispersive gradient fibres is also discussed for random index fluctuations. Mode coupled equations for temporal correlation functions of the electric field that are generalizations of coupled power equations are found. Mode filtering and pulse improvement with a lossy inhomogeneous cladding are described. 相似文献
70.
Yasumitsu Matsuo Junko Hatori Seiichiro Ikehata 《Journal of Physics and Chemistry of Solids》2005,66(1):127-131
We have investigated the molecular motions of TRIS+ ([(CH2OH)3CNH3]+) and ions in the [(CH2OH)3CNH3]2SiF6 crystal below room temperature from the measurements of the spin-lattice relaxation time T1 and the NMR absorption line of 1H and 19F nuclei, in order to elucidate the changes of the molecular motions by the phase transition of Tc=178 K. The narrowing of the 19F-NMR line was observed around Tc=178 K and the reorientation of the anion appears above Tc. Moreover, from the analysis of the temperature dependence of T1, we have observed that the activation energy of the reorientational motion of ions changes from 0.168 eV (T>Tc) to 0.185 eV (T<Tc). Based on these results, we found that the reorientational motion of ions is closely related to the origin of the phase transition at Tc. In addition, from the measurement of the 1H-NMR line, we also found that the reorientational motion of H2 in the -CH2OH group becomes active accompanied by the phase transition. 相似文献