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91.
T Konoshima M Kokumai M Kozuka M Iinuma M Mizuno T Tanaka H Tokuda H Nishino A Iwashima 《Chemical & pharmaceutical bulletin》1992,40(2):531-533
To search for possible anti-tumor-promoters, fourteen flavones obtained from the root of Scutellaria baicalensis were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Among these flavones, 5,7,2'-trihydroxy- and 5,7,2',3'-tetrahydroxyflavone showed remarkable inhibitory effects on the EBV-EA activation, and the effect of the latter on Raji cell cycle was also examined by flow cytometer. These two flavones exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test. 相似文献
92.
Okamoto Y Kawano M Kawabata T Kubota T Hiromitsu I 《The journal of physical chemistry. B》2005,109(1):288-296
The elucidation of a molecular structure of the active sites (i.e., the Co-Mo-S phase) of Co-Mo hydrodesulfurization catalysts has received extensive attention. In the present study, we unambiguously determined, for the first time, the NO adsorption behavior and magnetic property of the Co-Mo-S phase by preparing unique Co-Mo/Al(2)O(3) catalysts (CVD-Co/MoS(2)/Al(2)O(3)), in which all the Co atoms are present as the Co-Mo-S phase. The catalysts were characterized by NO adsorption (pulse technique and FTIR), Co K-edge XANES, and the magnetic susceptibility and effective magnetic moment of Co. Nitric oxide molecules were adsorbed on 33% of the Co atoms in CVD-Co/MoS(2)/Al(2)O(3) after sulfidation and on only half of the Co atoms even after an H(2)-treatment of the sulfided catalyst at 573-673 K. The Co atoms in CVD-Co/MoS(2)/Al(2)O(3) exclusively exhibited an antiferromagnetic property, indicating that even-numbered Co atoms are interacting with each other in the Co-Mo-S phase. A Co-Mo/Al(2)O(3) catalyst, prepared by a conventional impregnation technique, was composed of the antiferromagnetic Co sulfide species as observed in CVD-Co/MoS(2)/Al(2)O(3) in addition to Co(9)S(8). On the basis of the NO adsorption behavior and magnetic property, it is empirically proposed that the structure of the Co-Mo-S phase is represented as a Co sulfide dinuclear cluster located on the edge of MoS(2) particles. The magnetic property of Co/Al(2)O(3) sulfide catalysts depended on the preparation method. 相似文献
93.
94.
Yong Jin Lim Sung Hoon Kim Hiromitsu Hamano Toru Takagishi Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1986,24(3):503-510
Powdered Nylon 66 was prepared as a model of amorphous polymers. The resultant powder polyamide was composed of only amorphous regions. The extent of uptake of the acid azo dyes, a homologous series of methyl orange derivatives, by the polymer was measured in an aqueous solution. The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. The thermodynamic behaviors obtained are very similar to those of crosslinked polyvinylpyrrolidone. The favorable free energy of the binding is accompanied by an entropy gain and an exothermic enthalpy change. The shorter the alkyl chain of the dyes, the more negative is the enthalpy change and, hence, the smaller is the entropy change. The thermodynamic data for butyl orange showed that the binding process is athermal and is wholly an entropic effect. The binding of the dyes to the matrix is entropically favorable as a result of the operation of the hydrophobic effect. In addition, an electrostatic force is operative between the sulfonate group on the dyes and the terminal amino groups on the polyamide. 相似文献
95.
The RBCC (RING finger, B-box type zinc finger, coiled-coil domain) motif family contains a large number of proteins implicated in many cellular processes, including vesicle exocytosis. The acrosome reaction, the sperm exocytotic event that is required for fertilization, involves essentially the same process of intracellular membrane fusions as vesicular exocytosis in somatic cells. We have previously isolated a haploid-germ-cell-specific gene designated haprin, which encodes a RBCC motif protein that plays a role in the acrosome reaction of sperm by mediating protein complex formation via the RBCC motif. In this review, we describe the potential role of Haprin in the molecular mechanisms of acrosome reaction, as compared with some other RBCC proteins. The conserved structure and localization of the Haprin protein in human and mouse suggest an indispensable role for Haprin in the functioning of mammalian sperm. 相似文献
96.
Kitajima M Fujii N Yoshino F Sudo H Saito K Aimi N Takayama H 《Chemical & pharmaceutical bulletin》2005,53(10):1355-1358
Two new monoterpene glucosides, demethylsecologanol and 3'-O-glucosylsenburiside II, were isolated from Ophiorrhiza liukiuensis (Rubiaceae) together with 23 known compounds, including camptothecins and beta-carboline-type alkaloids. Their structures were determined by spectroscopic analysis. 相似文献
97.
Dr. Hiromitsu Sogawa Dr. Kayo Terada Yu Miyagi Prof. Dr. Masashi Shiotsuki Prof. Dr. Yoshihito Inai Prof. Dr. Toshio Masuda Prof. Dr. Fumio Sanda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6747-6755
A series of new photo‐responsive amino acid‐derived azobenzenedicarboxylic acid derivatives (S)‐ 1 a – e were synthesized. Compound (S)‐ 1 a in the trans form exhibited no circular dichroism (CD) signal in DMF under ambient conditions, whereas intense Cotton effects were observed upon UV irradiation, indicating the formation of a chiral supramolecular structure in the cis form. The CD signals disappeared when trifluoroacetic acid (TFA) was added to the solution. The ester counterpart [(S)‐ 1 a′ ] showed no CD signal. Hydrogen bonding between the carboxy groups seemed necessary for constructing the supramolecular structure. The kinetic studies of cis to trans isomerization of (S)‐ 1 a demonstrated that the formation of a chiral supramolecule enhances the stability of the cis‐azobenzene structure. The ESI mass spectrum of stilbenedicarboxylic acid (S)‐ 4 , an analogue of (S)‐ 1 b , confirmed the formation of a dimer. A theoretical CD study revealed that (S)‐ 1 a in the cis form should be present as a cyclic chiral dimer. 相似文献
98.
Ai Suzuki Katsuyoshi Nakamura Kotaro Okushi Nozomu Hatakeyama Hiromitsu Takaba Mark C. Williams 《Surface science》2009,603(20):3049-7652
The capability of theoretical durability studies to offer an efficient alternative methodology for predicting the potential performance of catalysts has improved in recent years. In this regard, multi-scale theoretical methods for predicting sintering behavior of Pt on various catalyst supports are being developed. Various types of Pt diffusions depending on support were confirmed by the micro-scale ultra accelerated quantum chemical molecular dynamics (UA-QCMD) method. Moreover, macro-scale sintering behavior of Pt/γ-Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts were studied using a developed 3D sintering simulator. Experimental results were well reproduced. While Pt on γ-Al2O3 sintered significantly, Pt on ZrO2 sintered slightly and Pt on CeO2 demonstrated the highest stability against sintering. 相似文献
99.
Hiromitsu Kiriyama Michiaki Mori Yoshiki Nakai Takuya Shimomura Manabu Tanoue Atushi Akutsu Hajime Okada Tomohiro Motomura Shuji Kondo Shuhei Kanazawa Akito Sagisaka Jinglong Ma Izuru Daito Hideyuki Kotaki Hiroyuki Daido Sergei Bulanov Toyoaki Kimura Toshiki Tajima 《Optics Communications》2009,282(4):625-2346
We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 1010 within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 1020 W/cm2. 相似文献
100.
Perhydropolysilazane (PHPS)—polymethylmethacrylate (PMMA)—spiropyran (SP) films were prepared by spin-coating using a solution
of a mass ratio, PHPS:PMMA:SP:xylene = 0.8:0.2:0.25:3.6. The SP-doped PHPS-PMMA films were then exposed to the vapor from
aqueous ammonia at room temperature, resulting in the formation of 1.7 μm thick, deep-red colored SP-doped PMMA-silica hybrid
films. Due to the high concentration of SP, which could be achieved by the hydrophobic nature of PHPS and xylene, the photochromic
color changes were visualized in spite of the small film thickness. The films had pencil hardness higher than 9H, and no SP
leaching was observed even when the films were soaked in xylene for 24 h. Thus, thin films that exhibit visual photochromism
with high mechanical and chemical durability could be prepared, which can never been achieved by conventional sol–gel methods. 相似文献