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71.
Etsushi Tsuji Ryosuke Nanbu Yoshiki Degami Kei Hirao Takeyuki Watanabe Naoya Matsumoto Satoshi Suganuma Naonobu Katada 《Particle & Particle Systems Characterization》2020,37(5):2000053
Brownmillerite-type Ca2FeCoO5 (CFCO) is one of the most effective catalysts for oxygen evolution reaction (OER), comparable with noble metal oxides. In this study, crystalline CFCO ultrasmall particles with nanometric dimension are synthesized by a reverse micelle method on TiO2 nanoparticles. The particle size decreases with decreasing molar ratio of water to surfactant. The precursors of CFCO must be calcined after loading on TiO2 nanoparticles to achieve CFCO ultrasmall particles with several nanometers in size. Interaction between the precursors and TiO2 is speculated to suppress aggregation of the precursors during calcination. The photocatalytic activity of TiO2 for OER is improved by loading of CFCO ultrasmall particles with 5 nm, whereas the activity decreases by loading of CFCO with more than 15 nm. Photocatalytic activity of the most active CFCO/TiO2 is comparable to that of RuO2/TiO2. Both the lower edge of conduction band and higher edge of valence band of CFCO are lower and higher than those of TiO2, respectively, leading to transfer of excited holes and electrons transferred to CFCO and recombination. When the particle size of CFCO becomes several nanometric dimensions, the transferred holes rapidly reach the surface of CFCO and oxidize water molecules before recombination with electrons. 相似文献
72.
Takeyuki Okada 《辐射效应与固体损伤》2013,168(1):337-342
Abstract Irradiation of KI near 150 K with KrCl excimer laser irradiation (hv=5. 58 eV) produces V centers causing V2 and V3 bands. The two bands exhibit 100-type dichroism. In KI containing V centers, the 111 cm?1 Raman signal attributed to I3- molecular ions is observed. Under KrCl excimer laser irradiation at low temperatures, resonance Raman scattering effects have been also studied for KI, NaI and LiI. 相似文献
73.
Takeyuki WAKABAYASHI 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(7):321-350
The author reviewed the research that led to establish the structural basis for the mechanism of the calcium-regulation of the contraction of striated muscles. The target of calcium ions is troponin on the thin filaments, of which the main component is the double-stranded helix of actin. A model of thin filament was generated by adding tropomyosin and troponin. During the process to provide the structural evidence for the model, the troponin arm was found to protrude from the calcium-depleted troponin and binds to the carboxyl-terminal region of actin. As a result, the carboxyl-terminal region of tropomyosin shifts and covers the myosin-binding sites of actin to block the binding of myosin. At higher calcium concentrations, the troponin arm changes its partner from actin to the main body of calcium-loaded troponin. Then, tropomyosin shifts back to the position near the grooves of actin double helix, and the myosin-binding sites of actin becomes available to myosin resulting in force generation through actin-myosin interactions. 相似文献
74.
Takeyuki Okada 《辐射效应与固体损伤》2013,168(1-4):271-275
Abstract The initial V2 and V3 bands observed after quenching of coloured KI crystals are found to be the superposition of absorption bands due to two kinds of V centres with ?110? and ?111? symmetries. The ratio of concentrations of the former to the latter V centers is estimated to be about 3:1. When a quenched crystal is irradiated at 19 K with V3-light in the 270-nm region, V centers are bleached forming I2-like centers. On the basis of the I3 molecule-ion model bound to a cation vacancy, a review is given of recent work on the photochemical conversion of V centers at low temperatures. 相似文献
75.
Mamoru Ozawa Takeyuki AmiIsao Ishihara Hisashi UmekawaRyosuke Matsumoto Yasuhiko TanakaTaku Yamamoto Yuya Ueda 《International Journal of Multiphase Flow》2009
Increasing attention has been focused on carbon dioxide (CO2) heat pump system where the temperature level is rather low, while the operating pressure is rather high. In this system, the density difference between vapor and liquid becomes rather small, which significantly affects flow patterns. Low surface tension and latent heat also have significant influence on two-phase flow patterns and heat transfer. This paper describes experimental and numerical investigation on flow patterns and heat transfer characteristics of boiling flow CO2 at high pressure in horizontal small-bore tubes ranging from 1.0 mm to 3.0 mm I.D. Even though the density difference is rather small at high pressure, phase stratification takes place, which leads to the intermittent dryout at the upper wall. So far developed discrete bubble model by the authors for vertical flows is modified so as to include horizontal flow mechanisms. The predicted flow patterns with this new model agree on the whole with the experimental observation. 相似文献
76.
Kuroda Y Ito K Itabashi K Kuroda K 《Langmuir : the ACS journal of surfaces and colloids》2011,27(5):2028-2035
Kaolinite nanoscrolls, rolled kaolinite sheets with a tubular form, were prepared by a one-step route in which intercalation of guest species and swelling with solvent proceed at the same time. A methoxy-modified kaolinite was exfoliated by the intercalation of hexadecyltrimethylammonium chloride. The formation of nanoscrolls by the one-step route proceeded only by several alkyltrimethylammonium salts and 1-hexadecyl-3-methylimidazolium chloride. Intercalation of primary amines caused the formation of nanoscrolls by a two-step route in which the intercalation and swelling proceed separately. The successful one-step route is ascribed to the relatively weak interactions between the head groups of guest species and the interlayer surface of methoxy-modified kaolinite, and the interaction is thought to allow the formation of a flexible array of interlayer guest species for swelling. The tubular structure was mostly retained after the heat treatment at 600 °C to form hierarchically porous aluminosilicates with amorphous frameworks. The nanoscrolls intercalated organic guests species, which are not directly intercalated into methoxy-modified kaolinite, between the scrolled layers. The formation route to nanoscrolls is quite dependent not only on the surface modification of kaolinite but also on the structure of guest species. 相似文献
77.
78.
Takeyuki Sone Rosaria D'Amato Yasuteru Mawatari Masayoshi Tabata Anita Furlani Maria Vittoria Russo 《Journal of polymer science. Part A, Polymer chemistry》2004,42(10):2365-2376
Copolymers of phenylacetylene (PA) and para‐nitrophenylacetylene (pNPA), named poly(PA‐co‐pNPA), were obtained in different PA/pNPA ratios and different reaction conditions with Rh(I) catalysts. The structure of the copolymers was investigated with IR, laser Raman, 1H NMR, electron spin resonance (ESR), and diffuse reflective ultraviolet–visible (DRUV) light spectroscopies. The pristine polymers had a cis–transoidal structure as the predominant conformation with some trans sequences. Detailed ESR studies supported by computer simulation and conformation analysis have suggested that the trans sequences were due to pNPA sequences and that the cis‐C?C bond sequences of pNPA were associated with a stabilized cis radical formed by four to five of pNPA monomers. This particular stabilization was probably the reason for the higher reactivity of pNPA as compared with PA. These cis sequences were preferentially cleaved to generate π radicals. The compression and, to a minor extent, thermal treatment of poly(PA‐co‐pNPA) samples induced a cis‐to‐trans isomerization, leading to a trans–transoidal form with a planar zigzag structure and with a conjugation length up to n = 24 repeat units, determined by DRUV and Raman experiments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2365–2376, 2004 相似文献
79.
Hollow aluminosilicate zeolite beta was successfully synthesized by adding CIT‐6, that is, zincosilicate zeolite, which has the same topology as beta, as seeds to the Na‐aluminosilicate gel without the need for organic structure‐directing agents. One important factor in the successful organic structure‐directing agent (OSDA)‐free synthesis of hollow beta crystals is the solubility of the seed crystals in alkaline media. CIT‐6 was less stable than aluminosilicate zeolite beta in alkaline media and the solubility changed depending on whether the crystals were calcined or not. The hollow beta could be obtained by using the uncalcined CIT‐6 seed crystals. The volumes of intra‐crystalline voids were tuned by changing the reaction time and the initial gel compositions, such as the SiO2/Al2O3 and Na2O/SiO2 ratios. We estimated that the intra‐crystalline voids were formed through the dissolution of the seed crystals, just after the crystal growth of new beta on the outer surface of the seeds. In addition, new crystal growth toward inside of the void was also observed by TEM. On the basis of the characterization data, such as chemical analysis, N2‐adsorption/desorption measurements, and TEM observation, a formation mechanism of the intra‐crystalline voids is proposed and discussed. 相似文献
80.