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41.
Katsuya Mukai Takuma Teshirogi Noriyuki Kuramoto Taku Kitamura 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1259-1265
Poly(2,5-dimethoxy-1,4-phenylene) was prepared by oxidative polymerization of p-dimethoxybenzene with aluminum chloride and copper(II) chloride in nitrobenzene under reduced pressure. The polymers obtained were soluble in sulfuric acid and fusible at 320°C. The intrinsic viscosity of the polymer was ca. 0.07 in sulfuric acid. Demethylation of methoxy groups did not occur during the polymerization. 相似文献
42.
We prove that the antiferromagnetic XXZ model with Ising-like anisotropy on a one-dimensional lattice does not have non-periodic ground states. 相似文献
43.
Taniguchi J Yamaguchi A Ishimoto H Ikegami H Matsushita T Wada N Gatica SM Cole MW Ancilotto F Inagaki S Fukushima Y 《Physical review letters》2005,94(6):065301
Heat capacity measurements have been made down to 5 mK for 3He fluid films adsorbed in one-dimensional (1D) nanometer-scale pores, 28 A in diameter, preplated with 4He of 1.47 atomic layers. At low 3He density, the heat capacity shows a density-dependent, Schottky-like peak near 150 mK asymptoting to the value corresponding to a 2D Boltzmann gas at high temperatures. The peak behavior is attributed to the crossover from a 2D gas to a 1D state at low temperatures. The degenerate state of the 1D 3He fluid is indicated by a predominantly linear temperature dependence below about 30 mK. 相似文献
44.
We propose an optical method for the investigation of the quantum dot edge channels by utilizing circularly polarized photoluminescence in the integer-quantum-Hall-effect regime. One of the advantages of our method is that the degree of the spin-polarization of the electrons in the inner- and outer-compressible liquids can be probed separately. The observed polarized photoluminescence spectra can be explained by the calculated electron spin-dependent optical transition probabilities based on the local-spin density approximation. 相似文献
45.
Aoyagi Y Saitoh Y Ueno T Horiguchi M Takeya K Williams RM 《The Journal of organic chemistry》2003,68(18):6899-6904
Lipase TL-mediated kinetic resolution of (+/-)-5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol (5) at low temperature proceeded to give the corresponding (S)-alcohol 5 and (R)-acetate 6 in quantitative yields with high enantiomeric purity. The addition of bases such as pyridine, DMAP, 2,4- and 2,6-lutidines, or triethylamine considerably enhanced the rate of kinetic resolution. The alcohol (S)-5 and the acetate (R)-6 were converted to piperazic acid derivatives (R)- and (S)-3, respectively, via the intramolecular Mitsunobu reaction as a key step. 相似文献
46.
Ken-ichi Fujita Satoshi UmekiManabu Yamazaki Taku AinoyaTeruhisa Tsuchimoto Hiroyuki Yasuda 《Tetrahedron letters》2011,52(24):3137-3140
We prepared magnetically recoverable osmium catalysts by use of magnetite, quaternary ammonium salts, and potassium osmate(VI), and applied them to the dihydroxylation of olefins. By employing 2 mol% of the magnetic osmium catalyst, the dihydroxylation reaction proceeded smoothly to provide the corresponding vicinal diol in a good chemical yield. The osmium catalyst was readily recovered by use of an external magnet, and was reused repeatedly. 相似文献
47.
A mechanistic study on the Nieuwland catalysis for dimerization of acetylene is performed by detecting copper–acetylene and copper–monovinylacetylene π‐complexes and also by examining the kinetics under virtually the same reaction conditions employed in the industrial process. An efficient H/D exchange occurs between acetylene and protons in the Nieuwland catalytic system. Addition of a coordinating ligand to the conventional Nieuwland catalytic system results in improvement of the catalytic activity and selectivity for the acetylene dimerization. The kinetic analysis including the kinetic deuterium isotope effect provides valuable insight into the Nieuwland catalytic mechanism of the dimerization of acetylene. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
48.
Yoshimune Nonomura Takaharu Fujii Yuichiro Arashi Taku Miura Takashi Maeno Kaoru Tashiro Yasuhisa Kamikawa Rie Monchi 《Colloids and surfaces. B, Biointerfaces》2009,69(2):1-267
Water has a unique touch as well as characteristic physical properties. However, nobody knows the real identity of its touch. Here, we show that water creates a stick-slip feel when a small amount is rubbed using fingertip on an artificial skin that mimics the structure of human skin. The results of frictional analyses predict that this stick-slip feel is caused by a drastic change in frictional resistance. The present result is valuable for biologists and robot engineers as well as cognitive scientists and tribologists, because it is a new example of stick-slip phenomena on biological surfaces. The tactile texture of this most familiar material could also be applied to consumer products or virtual reality systems. 相似文献
49.
Taku Onishi 《Polyhedron》2009,28(9-10):1792-1795
We performed the hybrid-density functional theory (DFT) calculations for the strongly correlated perovskite-type manganese fluorides of KMnF3, RbMnF3 and K1?xLixMnF3 In both solids, UBHHLYP, which contains 50% Hartree–Fock exchange term, provided the reasonable effective exchange integral (Jab) values, in comparison with the experimental ones. In order to investigate the intrinsic roles of counter cations precisely, we examined the variations of the total energy and Jab value, assuming the displacement of counter cation toward <1 0 0> direction. In KMnF3 (RbMnF3), it was found that the steric repulsion between potassium (rubidium) and bottleneck is large, while that between lithium and bottleneck is negligible in K1?xLixMnF3. Finally, we also showed the possibility of the lithium ion conduction in the antiferromagnetic K1?xLixMnF3. It was concluded that the lithium ion conduction in RMnF3 is possible, if the vacancy at R site exists. 相似文献
50.
Ekenechukwu C. Okafor Masaaki Tsukamoto Akihiro Hayakawa K.D. Kunkuma A. Somarathne Taku Kudo Taku Tsujimura Hideaki Kobayashi 《Proceedings of the Combustion Institute》2021,38(4):5139-5146
The influence of wall heat loss on the emission characteristics of ammonia-air swirling flames has been investigated employing Planar Laser-Induced Fluorescence imaging of OH radicals and Fourier Transform Infrared spectrometry of the exhaust gases in combustors with insulated and uninsulated walls over a range of equivalence ratios, ?, and pressures up to 0.5 MPa. Strong influence of wall heat loss on the flames led to quenching of the flame front near the combustor wall at 0.1 MPa, resulting in large unburned NH3 emissions, and inhibited the stabilization of flames in the outer recirculating zone (ORZ). A decrease in heat loss effects with an increase in pressure promoted extension of the fuel-rich stabilization limit owing to increased recirculation of H2 from NH3 decomposition in the ORZ. The influence of wall heat loss resulted in emission trends that contradict already reported trends in literature. NO emissions were found to be substantially low while unburned NH3 and N2O emissions were high at fuel-lean conditions during single-stage combustion, with values such as 55 ppmv of NO, 580 ppmv of N2O and 4457 ppmv of NH3 at ? = 0.8. In addition, the response of the flame to wall heat loss as pressure increased was more important than the effects of pressure on fuel-NO emission, thereby leading to an increase in NO emission with pressure. It was found that a reduction in wall heat loss or a sufficiently long fluid residence time in the primary combustion zone is necessary for efficient control of NH3 and N2O emissions in two-stage rich-lean ammonia combustors, the latter being more effective for N2O in addition to NO control. This study demonstrates that the influence of wall heat loss should not be ignored in emissions measurements in NH3-air combustion, and also advances the understanding of previous studies on ammonia micro gas turbines. 相似文献