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751.
Kenichi Hatanaka Soo-Chang Song Atsushi Maruyama Toshihiro Akaike Akira Kobayashi Hiroyoshi Kuzuhara 《Journal of carbohydrate chemistry》2013,32(8):1027-1037
AbstractStereoselective synthesis of α-D-glucosyl-branching polysaccharide by chemical and enzymic reactions was investigated. Ring-opening polymerization of 1,6-anhydro-3-O-benzoyl-2,4-di-O-benzyl-β-D-glucopyranose (1) with PF5 as catalyst at low temperature gave a highly stereoregular polymer, which was converted to 2,4-diO-benzyl-(1→6)-α-D-glucopyranan by debenzoylation with sodium methoxide. The polymer was glucosylated according to the glycosyl imidate method. Deprotection of the branched polysaccharide was carried out with sodium in liquid ammonia at -78 °C to give a (1→6)-α-D-glucopyranan having α-D-glucopyranosyl and β-D-glucopyranosyl branches. Only the β-D-glucopyranosyl branch of the polymer was completely removed by enzymatic hydrolysis by the use of cellulase to provide stereoregular (1→6)-α-D-glucopyranan having an α-D-glucopyranosyl branch at the C-3 position. Polymers were characterized by optical rotation, NMR spectroscopy, GPC, and X-ray diffractometry. 相似文献
752.
Hexabutyldistannane was found to be an effective mediator allowing the reaction of N-acyliminium ion pools with alkyl halides. A chain mechanism involving the addition of an alkyl radical generated from an alkyl halide to an N-acyliminium ion followed by the one-electron reduction of the resulting radical-cation by distannane was proposed. 相似文献
753.
Masato Kotsugi Takanori Wakita Toshiyuki Taniuchi Motohiro Suzuki Naoki Ishimatsu Hiroshi Maruyama 《Surface science》2007,601(20):4764-4767
We observed the spatially resolved X-ray absorption fine structure of meteoritic inclusion by photoelectron emission microscopy in conjunction with hard-X-ray synchrotron radiation. The cracked domain in the inclusion is identified as Cr2FeO4 (chromite), and its electronic structure shows identical behavior with that of synthetic chromite. The photon energy is also scanned over the extended region to obtain the radial distribution function. It finally shows almost identical behavior as synthetic chromite. 相似文献
754.
Brylewski T. Maruyama T. Nanko M. Przybylski K. 《Journal of Thermal Analysis and Calorimetry》1999,56(2):681-690
The high-temperature oxidation behavior of a ferritic alloy (SUS 430) in a SOFC environment, corresponding to the anode (H2/H2O gas mixture) and cathode (air) operating conditions, was determined with regard to application of the alloy as a metallic
separator material in SOFC. The oxidation kinetics of Fe-16Cr alloy (SUS 430), was studied by thermogravimetry in H2/H2O gas mixtures with pH/pHO=94/6 and 97/3 and in air, in the temperature range 1023-1223 K, for 3.6 up to 1080 ks. It was found that the protective oxide
scale, composed mainly of Cr2O3 with uniform thickness and excellent adhesion to the metal substrate, grows in accordance with the parabolic rate law. The
dependence of the parabolic rate constant, kp, of the scale on temperature obeys the Arrhenius equation: kp=6.8×10-4 exp (-202.3 kJ mol-1R-1T-1) for H2/H2O gas mixtures with pH/pHO=94/6. The determined kp was independent of the oxygen partial pressure in the range from 5.2×10-22 to 0.21 atm at 1073 K, which means that the rates of growth of the scale on Fe-16Cr alloy in the above-mentioned atmospheres
are comparable. The oxidation test results on Fe-16Cr alloy in H2/H2O gas mixtures and air demonstrate the applicability of SUS 430 alloys as a separator for SOFC.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
755.
756.
The relationships among the nominal thickness of Co catalyst, the structure of the catalyst particles, and the structure of carbon nanotubes (CNTs) growing from the catalyst during chemical vapor deposition were investigated. Various morphologies of CNTs such as individuals, random networks parallel to the surface of the substrate (‘grasses’), and vertically aligned forests of single- and multi-walled carbon nanotubes were grown by only varying the nominal thickness of catalyst under the same reaction condition. These different morphologies at the same growth time were due to the different areal density rather than to the length of CNTs. With increasing nominal thickness of catalyst, the catalyst particles changed in diameter while their areal density remained relatively almost constant. The change in diameter possibly affected the number ratio of active catalyst particles to the whole particles, which in turn affected the areal density of CNTs and yielded the various morphologies. Longer growth time increased the CNT length, which caused further change in CNT morphologies from individuals to grasses and grasses to forests. 相似文献
757.
758.
759.
Minoru Maruyama Ryo Matsubayashi Hiroaki Iwakuro Seiji Isoda Teruo Komatsu 《Applied Physics A: Materials Science & Processing》2008,93(2):467-470
We propose a lead-free silver paste as a replacement for a high-temperature lead-rich solder used for electronics. The pastes
tested here contain a small amount of solvent, but primarily consist of silver powder and alkoxide-passivated silver nanoparticles
that undergo nanosintering when heated. The pastes were used to connect silicon diode chips to copper bases at 350°C in nitrogen
ambient without external pressure. The resulting diode packages had electrical and thermal properties about equal to those
with lead-solder joints. The mechanical strengths also were comparable to the lead joint. These properties make this nanosilver
paste the first viable lead-free alternative to a lead solder. 相似文献
760.
Experimental results and analytical results are presented on chaotic vibrations of a shallow double-curved shell-panel subjected to gravity and periodic excitation. Modal interactions in the chaotic responses are discussed. The shell-panel with square boundary is simply supported for deflection. In-plane displacement at the boundary is elastically constrained. In the experiment, time histories of the chaotic responses at the spatial multiple positions of the shell-panel are measured for the inspection of modal interaction. In the analysis, the shallow shell-panel is assumed to have constant curvatures along to orthogonal directions and geometric initial imperfection. The Donnell-Mushtari-Vlasov type equation is used as governing equation with lateral inertia force. Assuming deflection with multiple modes of vibration, the governing equation is reduced to a set of nonlinear ordinary differential equations by the Bubnov-Galerkin procedure. Chaotic responses are integrated numerically. The chaotic responses, which are obtained by the experiment and the analysis, are inspected with the Fourier spectra, the Poincaré projections, the maximum Lyapunov exponents and the Lyapunov dimension. Contribution of modes of vibration to the chaotic responses is analyzed by the principal component analysis, i.e., Karhunen-Loève transformation. 相似文献