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21.
K. Akamatsu K. Nakahashi S. Ikeda H. Nawafune 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):377-380
Formation and structure of composite layer consisting of
polyimide films containing Ni nanoparticles were investigated.
The preparation method relies on KOH treatment on polyimide film
to form carboxyl acid groups and adsorption of Ni ions by ion
exchange followed by hydrogen reduction. The amount of Ni ions
adsorbed in polyimide films were found to be systematically
controlled by changing initial KOH concentration, subsequent ion
exchange time, pH and temperature. Cross-sectional TEM
observation revealed that Ni nanoparticles with 3-5 nm in
diameter were homogeneously dispersed in the surface modified
polyimide layer after heat treatment above 250
°C in H2
atmosphere. The size and distribution of the Ni nanoparticles
were strongly dependent on the heat treatment temperature,
indicating that this method allows microstructural tuning of
metal/polymer nanocomposites. 相似文献
22.
I. Mori Y. Fujita K. Ikuta Y. Nakahashi K. Kato 《Analytical and bioanalytical chemistry》1989,334(3):252-255
23.
Dr. Tomoya Miura Junki Nakahashi Prof. Dr. Masahiro Murakami 《Angewandte Chemie (International ed. in English)》2017,56(24):6989-6993
(E)-δ-Boryl-substituted anti-homoallylic alcohols are synthesized in a highly diastereo- and enantioselective manner from 1,1-di(boryl)alk-3-enes and aldehydes. Mechanistically, the reaction consists of 1) palladium-catalyzed double-bond transposition of the 1,1-di(boryl)alk-3-enes to 1,1-di(boryl)alk-2-enes, 2) chiral phosphoric acid catalyzed allylation of aldehydes, and 3) palladium-catalyzed geometrical isomerization from the Z to E isomer. As a result, the configurations of two chiral centers and one double bond are all controlled with high selectivity in a single reaction vessel. 相似文献
24.
Mutsumi Nakahashi Kazuaki Mawatari Akiko Hirata Miki Maetani Takaaki Shimohata Takashi Uebanso Yasuhiro Hamada Masatake Akutagawa Yousuke Kinouchi Akira Takahashi 《Photochemistry and photobiology》2014,90(6):1397-1403
Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320–400 nm), UVB (280‐320 nm), and UVC (<280 nm). We previously developed UVA sterilization equipment with a UVA light‐emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA‐LED and another UV wavelength. An oxidative DNA product, 8‐hydroxy‐2’‐deoxyguanosine (8‐OHdG), increased after irradiation by UVA‐LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA‐LED and UVC‐induced additional bactericidal effects, simultaneous irradiation with UVA‐LED and UVC‐induced bactericidal synergistic effects. The 8‐OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response‐deficient mutants, such as the recA and lexA strains. Because recA‐ and lexA‐mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on the suppression of the CPDs repair. The simultaneous irradiation of UVA‐LED and UVC is a candidate new procedure for effective water disinfection. 相似文献
25.
This paper presents a reliable and automated approach to the generation of unstructured hybrid grids comprised of tetrahedra, prisms and pyramids for high Reynolds number viscous flow simulations. To enhance robustness, the hybrid mesh generation process starts with the formation of an isotropic tetrahedral grid. Prismatic layers are then added on no‐slip walls fully automatically by obeying user‐specified boundary conditions and three parameters: the number of the layers, an initial layer thickness normal to the walls, and a stretching factor. Topological modifications to the original isotropic tetrahedral elements are prohibited during the layer generation process. The tetrahedral elements near no‐slip walls are shifted inward and the resulting gap between the tetrahedra and the walls is filled up with prismatic elements. To enhance the quality of the prismatic layers around sharp corners, two normals are evaluated for the marching process in these regions. The addition of prismatic elements is locally stopped if negative‐volume elements are created or not enough space is left. An angle‐based smoothing method ensures that the quality of the tetrahedral elements is retained for a reasonable computational cost. The method is demonstrated for two scaled experimental supersonic airplane models designed at the National Aerospace Laboratory of Japan (NAL). Numerical results are compared with wind tunnel experimental data. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
26.
Akiko Nakahashi Masaki Fujita Eisuke Miyoshi Tomokazu Umeyama Kensuke Naka Yoshiki Chujo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3580-3587
The reaction of phenyl propynyl ether and diphenyl disulfide in the presence of 1 mol % tetrakis(triphenylphosphine)palladium as a model reaction of the polymerization of bis(4‐prop‐2‐ynyloxyphenyl) disulfide ( 1a ) gave a Z‐substituted dithioalkene. No E‐substituted dithioalkene was formed in this reaction. The palladium‐catalyzed bisthiolation polymerization of a diethynyl disulfide derivative, 1a , in benzene, was carried out to give a hyperbranched polymer ( 5a ) containing a Z‐substituted dithioalkene unit after reaction for 4 h at 70 °C. From the gel permeation chromatography analysis (chloroform, PSt standards), the number‐average and weight‐average molecular weights of 5a were found to be 8,100 and 57,000, respectively. The structure of 5a was confirmed by 1H and 13C NMR spectra. The obtained polymer was soluble in common organic solvents such as benzene, acetone, and CHCl3. Polymerization for more than 5 h gave insoluble products. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3580–3587, 2007 相似文献
27.
Takuma Fujita Shunsuke Kuwahara Atsufumi Nakahashi John Decatur 《Tetrahedron letters》2007,48(24):4219-4222
Enantiopure (R)-(+)-[VCD(+)945]-4-ethyl-4-methyloctane, the simplest chiral saturated hydrocarbon with a quaternary stereogenic center, was synthesized by the use of MαNP acid method, and its absolute configuration was first unambiguously determined by the 1H NMR anisotropy, X-ray crystallography, and VCD methods. 相似文献
28.
Yotaro Morishima Yoshihiro Itoh Atsufumi Koyagi 《Journal of polymer science. Part A, Polymer chemistry》1983,21(4):953-960
For a fundamental study of the electrochemical behavior of electroactive polymers a series of poly(3-vinyl-10-methylphenothiazine) (polyMPT), copolymers of 3-vinyl-10-methylphenothiazine and methyl methacrylate (MMA) (copolyMPT), and 3-ethyl-10-methylphenothiazine (EMPT) (a related monomer model) were prepared. The methylphenothiazine groups in these compounds showed reversible, one-electron oxidation waves in the triangular-were voltammograms. From a detailed comparison of the voltammograms between these polymers and EMPT it was revealed that the electroactive groups in poly MPT were not the “noninteracting” centers in the strict sense, whereas those in copolyMPT, in which the centers are spaced with the MMA segments, were typically noninteracting in nature; that is, in polyMPT the oxidation takes place at the potential 40 m V lower than that of EMPT and copolyMPT exhibited a wave identical to that of EMPT in shape and potential. The exhaustive electron transfer occurred from polyMPT to the electrode. On the other hand, a significant number of centers remained unoxidized in copolyMPT. The self-exchange electron transfer within the polymer coil facilitates the exhaustive oxidation. For this event the proximity of the centers was an essential factor. 相似文献
29.
M Yamashita T Inaba Y Oda N Mizukawa Y Ushijima S Furuya H Nakahashi 《Radioisotopes》1990,39(12):577-580
Twenty subjects inhaled C15O and its dynamics were monitored to determine when equilibrium between the aorta and kidney occurred. One minute after inhalation, the increase in radioactivity in the aorta paralleled that in the kidney, but thereafter, both declined slowly. The ratio of aorta/kidney radioactivity become constant 1 min after inhalation and remained unchanged for 4 min. Thus renal blood volume can be measured 1 min after inhalation of C15O its distribution in the aorta and kidney has attained equilibrium. 相似文献
30.
I Mori Y Fujita K Ikuta S Kitano H Kawabe Y Nakahashi K Kato Y Inamori 《Chemical & pharmaceutical bulletin》1989,37(7):1827-1830
The fluorescence quenching reaction between fluorescein mercury or halogeno-fluorescein mercury compounds (fl. Hg, 2,7- or 2,4-dichloro-fl.Hg, 3',4',5',6'-tetrachloro-fl.Hg, mercurochrome) and beta-lactam antibiotics (ampicillin (AB-PC) and cephalexin (CEX] was investigated, and mercurochrome was selected for the detection of beta-lactam antibiotics; the detection limit was about 0.8 micrograms/ml. A fluorimetric assay of beta-lactam antibiotics was established by measuring the fluorescence of mercurochrome and mercurochrome-beta-lactam antibiotics solutions in weakly basic media to determine the degree of fluorescence quenching. The maximum emission wavelength of mercurochrome solution was at 544 nm with excitation at 470 nm. The calibration graphs were linear over the ranges of about 0-6 micrograms/ml beta-lactam antibiotics penicillins (AB-PC, penicillin G, sulbenicillin, amoxicillin, cyclacillin, oxacillin, hetacillin and piperacillin) and cepham antibiotics (CEX, cefazolin, cephaloglycin, cephaloridine and cefpyramide), and the relative standard deviation was 2.7% for 1.4 micrograms/ml of AB-PC (n = 5). This fluorescence quenching reaction between mercurochrome and beta-lactam antibiotics was applied in a survey of decomposition and remaining potency of beta-lactam antibiotics. 相似文献