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41.
Formation mechanisms of silver (Ag) particles in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by the photoreduction of AgClO(4) were investigated by means of in situ small-angle X-ray scattering (SAXS) measurements. The kinetics of association process (nucleation, growth, and coalescence) of Ag(0) atoms to produce Ag particles was successfully revealed by the quantitative SAXS analysis for the number-average of radius (R(0)), number of particles (n(Ag)), reduced standard deviation (σ(R)/R(0)), and volume fraction (?(Ag)) of Ag particles produced by the photoreduction. The rate of nucleation and growth process during Ag particle formation strongly depend on the initial metal concentration. The time evolution of radius and number of Ag particles indicates that a mechanism of Ag particle formation is composed of different three processes, that is, reduction-nucleation, Ostwald ripening, and particle coalescence. In a rapid reduction-nucleation process, small nuclei or particles (average radius ~2.5 nm) are produced by an autocatalytic reduction. After the formation of small nuclei or particles proceeds, Ostwald ripening and particle coalescence, predicted by the Lifshitz-Slyozov-Wagner theory (LSW theory), subsequently occur, resulting in the particle growth (average radius ~11.5 nm). 相似文献
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43.
The concept of relative t-designs for Q-polynomial association schemes is due to Delsarte (Philips Res Rep 32:373–411, 1997). We formulate Fisher type lower bounds as well as the concept of tight relative 2- and 4-designs very explicitly for binary Hamming association schemes H(n, 2). Then we discuss some examples of tight relative 2- and 4-designs on H(n, 2) in this sense, in connection with the work of Woodall (Proc Lond Math Soc (3) 20:669–687, 1970), Enomoto-Ito-Noda (Osaka J Math 16:39–43, 1979), and others. The present paper is expected to be the first of a series of our studies of tight relative t-designs on Q-polynomial association schemes in a more general context. 相似文献
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45.
Keiko Doi-Kawano Etsuko Nishimoto Yoshiaki Kouzuma Daisuke Takahashi Shoji Yamashita Makoto Kimura 《Journal of fluorescence》2009,19(4):631-639
The steady-state and time-resolved fluorescece spectroscopy is one of the most powerful method to detect and analyze subtle
conformation change and interaction between peptide elements in protein. Phytocystatin Scb isolated from sunflower seeds includes
a single Trp residue at position 85. In an attempt to investigate the interaction of the N-terminal region of Scb with the
first and second hairpin loops by fluorescence spectroscopy of Trp residue, two Scb mutants in which single Trp locates at
position 52 and 58, respectively, and their N-terminal removed mutants were generated. The N-terminal truncation changed the
fluorescence decay kinetics of Trp52 from the triple exponential to double. Furthermore, the time-resolved fluorescence anisotropy
residue indicated that the segmental motion of Trp52 was significantly enhanced by its N-terminal truncation. In contrast,
Trp58 and Trp85 had little influence. The N-terminal successive truncations of Scb and its mutants resulted in the weaken
inhibitors to papain. These results suggested that the N-terminal region of Scb interacts with the peptide segment preceding
the first hairpin loop, thereby stabilizing the conformation of the hairpin loop structure. 相似文献
46.
47.
The metabolites 3 and 4 of 2-(4-ethyl-1-piperazinyl)-4-phenylquinoline dimaleate (AS-2646, 1), a candidate as a gastric antisecretory and antiulcer drug, were synthesized to confirm the proposed structures. The effects of the metabolites 2-4 on ulcer induced by stress were determined. 相似文献
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49.
Komal Garg Yasuo Matsubara Mehmed Z. Ertem Anna Lewandowska‐Andralojc Shunsuke Sato David J. Szalda James T. Muckerman Etsuko Fujita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(47):14334-14338
We prepared two geometric isomers of [Ir(tpy)(ppy)H]+, previously proposed as a key intermediate in the photochemical reduction of CO2 to CO, and characterized their notably different ground‐ and excited‐state interactions with CO2 and their hydricities using experimental and computational methods. Only one isomer, C‐trans‐[Ir(tpy)(ppy)H]+, reacts with CO2 to generate the formato complex in the ground state, consistent with its calculated hydricity. Under photocatalytic conditions in CH3CN/TEOA, a common reactive C‐trans‐[Ir(tpy)(ppy)]0 species, irrespective of the starting isomer or monodentate ligand (such as hydride or Cl), reacts with CO2 and produces CO with the same catalytic efficiency. 相似文献
50.
Copper-mediated chemoselective trifluoromethylation at the benzylic position by the use of shelf-stable electrophilic trifluoromethylating reagents 3 in good to high yields under mild conditions is described for the first time. The generality of this trifluoromethylation for a wide variety of benzyl bromides facilitates the rapid creation of structural diversity of medicinal candidates in drug discovery. 相似文献