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161.
162.
Preparation of ZnO nanoparticles in a reverse micellar system and their photoluminescence properties
ZnO nanoparticles with spherical morphology and narrow size distribution were obtained by calcination of Zn(OH)2 nanoparticles, which were prepared in a polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar system and incorporated into polyurea (PUA) via an in situ polymerization of hexamethylene diisocyanate (HDI). The resulting ZnO nanoparticles demonstrated a near-UV emission and a green emission, the intensity ratio of which depended on calcination conditions. For the nanoparticles studied, the calcination atmosphere influenced remarkably the photoluminescence properties such as intensity ratio of the near-UV emission to green emission, rather than the size, morphology, and crystallinity of the ZnO nanoparticles. The green emission decreased by calcination in O2 flow but increased by calcination in N2 flow, as compared with the case calcined in air flow. This finding suggests that the green emission is enhanced with the increase of the number of oxygen vacancies of the ZnO nanoparticles and thus the photoluminescence properties of the nanoparticles were successfully controlled by the calcination condition, without changing the size and morphology. 相似文献
163.
Volume reduction(N), tritium retention factor (R), tritium concentration factor(Z) and apparent separation factor(beta) were measured on the large and small electrolytic cell systems. The relative variation of R was smaller than that of Z. So, it is recommended to use R in calculation of tritium concentrations in water samples. Furthermore, it was empirically revealed that R can be obtained only from N if a reliable beta-value is previously known. Therefore, it is possible to obtain R without electrolysis of the tritium standard solution. Taking into account the above facts, the so-called non-spike analysis of tritium, in which electrolytic enrichment and liquid scintillation counting are combined, becomes practicable. 相似文献
164.
Hirai K Uehara H Kitagawa S Furukawa S 《Dalton transactions (Cambridge, England : 2003)》2012,41(14):3924-3927
A series of 1,1'-ferrocenedicarboxylate-based two-dimensional porous coordination polymers were synthesized by incorporating different diamine co-ligands. These compounds immobilized on electrodes, exhibited reversible redox reactions, arising from ferrocenyl moiety. 相似文献
165.
Mathematical Programming - Many practical integer programming problems involve variables with one or two-sided bounds. Dunkel and Schulz (A refined Gomory–Chvátal closure for polytopes... 相似文献
166.
Takahiro Moriyama Daiki Mizukami Dr. Makoto Yoritate Dr. Kazuteru Usui Dr. Daisuke Takahashi Dr. Eisuke Ota Prof. Dr. Mikiko Sodeoka Prof. Dr. Tadashi Ueda Prof. Dr. Satoru Karasawa Prof. Dr. Go Hirai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(11):e202103925
Minimalist photo-reactive probes, which consist of a photo-reactive group and a tag for detection of target proteins, are useful tools in chemical biology. Although several diazirine-based and aryl azide-based minimalist probes are available, no keto-based minimalist probe has yet been reported. Here we describe minimalist probes based on a 2-thienyl-substituted α-ketoamide bearing an alkyne group on the thiophene ring. The 3-alkyne probe showed the highest photo-affinity labeling efficiency. 相似文献
167.
Mika Sakai Masayoshi Mori Dr. Masato Hirai Dr. Naoki Ando Prof. Dr. Shigehiro Yamaguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200728
Two kinds of planarized phenyldithienylboranes, which contain (CH3)2C- or CH2-bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH3)2C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state. A series of π-extended derivatives was synthesized, among which a p-(diphenylamino)phenyl-substituted derivative shows large solvatochromism in the fluorescence spectra, while maintaining high quantum yields even in polar solvents. The Lewis acidity of the phenyldithienylborane derivatives was also assessed by titration with pyridine. The Lewis acidity of the boron center is affected not only by the difference in the steric bulk of the bridging moieties, but also by the electronic effect of the substituents introduced at remote positions relative to the boron atom. These results demonstrate the characteristic features of planarized phenyldithienylboranes as building blocks for boron-based π-electron materials. 相似文献
168.
Hidehito Nanto Fumitaka Endo Yoshiaki Hirai Shouichi Nasu Nozomu Takeuchi 《Optical Review》1994,1(2):177-179
Intense photostimulated luminescence (PSL) with a peak at 420 nm is observed in ultraviolet (UV) Iight-irradiated europium-doped potassium chloride (KCl: Eu) crystalline phosphors. The PSL characteristics of UV-irradiated KCl: Eu phosphor for optical memory application were studied. The excitation and emission mechanisms of the 420 nm PSL, which are consistent with the results obtained, are discussed. 相似文献
169.
Tsukamoto D Ikeda M Shiraishi Y Hara T Ichikuni N Tanaka S Hirai T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(35):9816-9824
Semiconductor TiO2 particles loaded with WO3 (WO3/TiO2), synthesized by impregnation of tungstic acid followed by calcination, were used for photocatalytic oxidation of alcohols in water with molecular oxygen under irradiation at λ>350 nm. The WO3/TiO2 catalysts promote selective oxidation of alcohols to aldehydes and show higher catalytic activity than pure TiO2. In particular, a catalyst loading 7.6 wt % WO3 led to higher aldehyde selectivity than previously reported photocatalytic systems. The high aldehyde selectivity arises because subsequent photocatalytic decomposition of the formed aldehyde is suppressed on the catalyst. The TiO2 surface of the catalyst, which is active for oxidation, is partially coated by the WO3 layer, which leads to a decrease in the amount of formed aldehyde adsorbed on the TiO2 surface. This suppresses subsequent decomposition of the aldehyde on the TiO2 surface and results in high aldehyde selectivity. The WO3/TiO2 catalyst can selectively oxidize various aromatic alcohols and is reusable without loss of catalytic activity or selectivity. 相似文献
170.
Hidefumi Hirai Makoto Komiyama 《Journal of polymer science. Part A, Polymer chemistry》1975,13(11):2419-2435
The alternating copolymerization of methyl methacrylate with styrene in the presence of stannic chloride at ?50°C in toluene was kinetically investigated both under photoirradiation and with the tri-n-butylboron-benzoyl peroxide initiator. The concentrations of the binary and ternary molecular complexes in the copolymerization solution were estimated by use of the equilibrium constants. The rates are found to be proportional to the 1.5th and 1.0th orders of the concentration of the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The conversion increases proportionally with the polymerization time, while the degree of polymerization is constant irrespective of the time. The rates depend linearly upon the square root of the intensity of the incident light and upon the concentration of tri-n-butylboron, respectively. The alternating copolymerization is confirmed experimentally to precede the homopolymerization of the monomer charged in large excess both under photoirradiation and with initiator. The kinetic results indicate consistently that the alternating copolymerization proceeds through the homopolymerization of the ternary molecular complex in the steady state with a bimolecular termination. Both the conventional radical mechanism and the double complex mechanism are unsuitable for the present alternating copolymerization. 相似文献