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11.
Hayashi Y Aratake S Itoh T Okano T Sumiya T Shoji M 《Chemical communications (Cambridge, England)》2007,(9):957-959
Dry and wet prolines were found to catalyze the direct aldol reactions of aldehyde-aldehyde and aldehyde-ketone, respectively, to afford aldols with excellent diastereo- and enantioselectivities, and an organic solvent-free reaction was realized in some cases. 相似文献
12.
Aratake S Itoh T Okano T Nagae N Sumiya T Shoji M Hayashi Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10246-10256
Proline-based organocatalysts have been developed for a highly enantioselective, direct aldol reaction of aldehydes and ketones in the presence of water. While several surfactant-proline combined catalysts have proved effective, proline derivatives with a hydrophobic moiety such as trans-siloxy-L-proline and cis-siloxy-D-proline, both of which are easily prepared from the same commercially available 4-hydroxy-L-proline, have been found to be the most effective organocatalysts examined in this study, affording the aldol product with excellent diastereo- and enantioselectivities, these two catalysts generating opposite enantiomers. Water affects the selectivity, and poor results are obtained under neat reaction conditions or in dry organic solvents. More than three equivalents of water are required for the best diastereo- and enantioselectivities, while three equivalents is the recommended amount from a synthetic point of view. The reaction proceeds in the organic phase, and also proceeds in the presence of a large amount of water. The large-scale preparation of aldols with the minimal use of an organic solvent, including in the purification step, is described. 相似文献
13.
Micromachining and surface processing of the super-hard nano-polycrystalline diamond by three types of pulsed lasers 总被引:1,自引:0,他引:1
Takuo Okuchi Hiroaki Ohfuji Shoko Odake Hiroyuki Kagi Syohei Nagatomo Mitsuru Sugata Hitoshi Sumiya 《Applied Physics A: Materials Science & Processing》2009,96(4):833-842
Laser beam micromachining was applied to super-hard nano-polycrystalline diamond (NPD) synthesized by the direct conversion
of graphite at high pressure and high temperature. Three types of pulsed lasers were tested: nanosecond near-infrared, nanosecond
near-ultraviolet, and femtosecond near-infrared lasers. The latter two were also applied for synthetic single crystal of diamond
to compare the results with those of the NPD. It was demonstrated that the nanosecond near-infrared laser was the most efficient
device for rough shaping of the NPD, while the ultraviolet and femtosecond lasers give satisfactory results for precise surface
finishing of it. The properties of the laser-processed surfaces were analyzed by scanning and transmission electron microscopy,
laser scanning microscopy, and micro Raman spectroscopy. These analyses demonstrated that the three types of lasers play different
and complementary roles, and that their combination is the best suitable solution for micromachining of the hardest diamond
into any desired shapes. 相似文献
14.
S Sumiya T Yoneda K Kitamura M Murata C Yokoo M Tamai A Yamamoto M Inoue T Ishida 《Chemical & pharmaceutical bulletin》1992,40(2):299-303
To design a potent inhibitor specific for cathepsin B (rat liver), the tertiary structure was predicted based on the crystal structure of the papain complexed with (+)-(2S,3S)-3-(1-[N-(3-methylbutyl)amino]leucylcarbonyl)oxirane-2- carbolylic acid (E-64-c), a thiol protease inhibitor. Taking advantage of the structural characteristics of the predicted active site, seventeen inhibitors were chemically synthesized by molecular modeling, and one of them, N-(L-3-trans-propylcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-p rol ine (CA-074) was shown to be the first potent inhibitor specific for cathepsin B. The relationship between the structure and inhibitory activity is discussed based on the model structure of the cathepsin B-inhibitor complex. 相似文献
15.
Ken‐ichi Sumiya Giseop Kwak Fumio Sanda Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2004,42(11):2774-2783
This article concerns the hydrosilylation polyaddition of 1,4‐bis(dimethylsilyl)benzene ( 1 ) with 4,4′‐diethynylbiphenyl, 2,7‐diethynylfluorene ( 2b ), and 2,6‐diethynylnaphthalene with RhI(PPh3)3 catalyst. Trans‐rich polymers with weight‐average molecular weights (Mw's) ranging from 19,000 to 25,000 were obtained by polyaddition in o‐Cl2C6H4 at 150–180 °C, whereas cis‐rich polymers with Mw's from 4300 to 34,000 were obtained in toluene at 0 °C–r.t. These polymers emitted blue light in 4–81% quantum yields. The cis polymers isomerized into trans polymers upon UV irradiation, whereas the trans polymers did not. The device having a layer of polymer trans‐ 3b obtained from 1 and 2b demonstrated electroluminescence without any dopant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2774–2783, 2004 相似文献
16.
Akira Abe Naoko Aoyama Satoshi Sumiya Noriyoshi Kakuta Kiyohide Yoshida 《Reaction Kinetics and Catalysis Letters》1998,65(1):139-144
The influence of SO2 (200 ppm) on the durability of a Ag/Al2O3 catalyst for the reduction of NOx with ethyl alcohol was examined. The results strongly suggest that H2O in diesel engine exhaust is essential for the high durability of Ag/Al2O3 catalyst in the presence of SO2. 相似文献
17.
Y. Muramatsu S. Uchida M. Sumiya Y. Ohmomo 《Journal of Radioanalytical and Nuclear Chemistry》1985,94(5):329-338
A radiochemical neutron activation analytical method for the determination of129I and127I in soil samples was studied. Iodine was separated from the sample prior to the irradiation by volatilization, i.e. by combustion of the sample and trapping of the iodine in an alkaline solution together with a reducing agent. This method enables one to digest samples containing up to 100 g dry matter. The chemical yield was mostly more than 90%. After irradiation the iodine fraction was further purified by solvent extraction. The detection limit of the129I/127I ratio was 1×10–9. 相似文献
18.
T. Harada I. Ohkubo M. Lippmaa Y. Matsumoto M. Sumiya H. Koinuma M. Oshima 《固体物理学:研究快报》2011,5(1):34-36
Ferromagnetic insulator Pr0.8Ca0.2Mn1–yCoy O3 (0 ≤ y ≤ 0.7) thin films were epitaxially grown by pulsed laser deposition on substrates of (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (100). To probe the ferromagnetic insulator state, the Co content dependences of the structural, magnetic, and transport properties were studied. Variation of lattice constant by the Co substitution is well reproduced considering that divalent and trivalent Co ions substitute for Mn ions at the perovskite B‐sites. For 0 ≤ y ≤ 0.3, the Curie temperature, saturation magnetization, and magnetoresistance increase with increasing Co content, retaining the insulating properties. Detailed analyses of transport and magnetic properties indicate the contribution of both double exchange and superexchange interactions to the appearance of the ferromagnetic insulating phase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
Takayuki Tanaka Kentaro Sano Masafumi Ando Ami Sumiya Hidetaka Sawada Fumio Hosokawa Eiji Okunishi Yukihito Kondo Kunio Takayanagi 《Surface science》2010,604(23-24):L75-L78
In-situ gas-injection transmission electron microscopy revealed that a pillar grew at the edge of the interface of a gold nanoparticle and a TiO2 substrate during exposure to O2 gas at 100 Pa. The pillar was found to have a titanium-deficient chemical composition of Ti1 ? xO2 (x > 0) by electron energy loss spectroscopy (EELS). The spectra showed a chemical shift of oxygen and titanium ions to have ionic states of Ti3+ and Oy? (y < 3/2). The formation of the Ti1 ? xO2 at the contact edge of gold–Ti1 ? xO2 interface is discussed from the perspective of an O2 affinity, which plays an important role in CO oxidation process of supported gold particle. 相似文献
20.
Shock Waves - Oblique detonation waves (ODWs) were stabilized by launching a spherical projectile with 1.2–1.4 times the Chapman–Jouguet (C–J) velocity into detonable mixtures at... 相似文献