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991.
The local structures of Ag3AsS3 glass at 80 and 300 K have been investigated by extended X-ray absorption fine structure analysis. By comparing the glass structure with that of Ag3AsS3 crystal (proustite), the possibility of ionic conduction by this glass is discussed. The local structure around an As atom in the glass is similar to that in the crystal. This fact suggest that, even in the glass structure, the As atoms from AsS3 trigonal pyramids of shape similar to that in the crystal. The Ag---S distance (2.449 Å at 300 K) and the large root mean square displacement, σ, for the Ag---S atomic pairs in the glass, groups with a by the parameter fitting method, show that the Ag atoms are quite randomly distributed around the AsS3 groups with a similar Ag---S distance to that in the crystal. Further, it is possible that the large thermal contribution to σAg---S2 for the glass may indicate the involvement of the Ag atoms in ionic conduction. 相似文献
992.
The medium-range structure of a heat-treated Al85Y10Ni5 amorphous alloy was investigated by small-angle X-ray scattering, calorimetric analysis, wide-angle X-ray diffraction and transmission electron microscope measurements. It is observed that crystalline particles having a definite boundary are precipitated by annealing at supercooled liquid temperatures and that most of the precipitates consist of the Al fcc crystalline phase. The integrated intensities of the small-angle scattering and the Guinier radii of the precipitates increase on annealing for time duration <5.4 ks. However, as the annealing time becomes > 5.4 ks, the integrated intensities and the Guinier radii are invariant, i.e., growth of the precipitates ceases. After annealing for 518.4 ks, the diameters of the precipitates exhibit a narrow distribution centered around 200 Å. 相似文献
993.
Satoru Amou Kazuhiko Takeuchi Michihiko Asai Kouichi Niizeki Takashi Okada Makoto Seino Osamu Haba Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》1999,37(19):3702-3709
Regiocontrolled polymer (2) having 2-naphthol unit was prepared by oxidative coupling polymerization of bis(2-naphthol) (1). Polymerizations were conducted in dichloromethane in the presence of [di-μ-hydroxo-bis(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride [CuCl(OH)TMEDA] under air at room temperature, producing polymers with number-average molecular weights up to 12,000. The structure of polymer 2 was characterized by 270 MHz 1H–NMR and 68.5 MHz 13C–NMR spectroscopies and was estimated to consist almost completely of 1,1′-linkage. The polymer was readily soluble in polar aprotic solvents and tetrahydrofuran at room temperature. Thermogravimetric analysis of polymer 2 showed 10% weight loss at 450°C in nitrogen. The model reactions were studied to clarify the applicability of CuCl(OH)TMEDA for coupling of naphthol derivatives. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3702–3709, 1999 相似文献
994.
Kiyoichi Matsumoto Hiroyuki Uejima 《Journal of polymer science. Part A, Polymer chemistry》1997,35(10):1949-1954
An alcoholic–aqueous solution of LiBr·H2O is a useful solvent for silk fibroin, if the ratio of alcohol content to water content therein is 1 or more. The mixed solvents consisting of ethanol, water, and LiBr·H2O showed a higher solubility if they contained a lesser amount of water. They further proved able to easily dissolve more than 20% by weight of silk fibroin. Solvents poorer in water content and richer in LiBr·H2O showed a higher value of [η]; Huggins' coefficient of said solutions varied within a range 0.5–1.0, the minimum appearing at a water content of about 10% weight. Fibroin molecules remained stable in those solutions. The novel solvents for silk fibroin that have been developed by us are named “MU solvents,” by taking the initials in the names of Matumoto/Uejima. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1949–1954, 1997 相似文献
995.
996.
997.
K. Feng M. Tsushima T. Matsumoto T. Kurosaki 《Journal of polymer science. Part A, Polymer chemistry》1998,36(5):685-693
Two chalcone-derivative isomers, 4,4′-diaminochalcone ( 4DAC ) and 3,3′-diaminochalcone ( 3DAC ), were synthesized and used as monomers together with tetracarboxylic dianhydrides to prepare novel photosensitive polyimides that contain a chalcone moiety in the main chain. The polyimides were characterized and their photochemical behavior was investigated as thin films and in solutions with the aid of ultraviolet and infrared spectroscopy. Compared with 4DAC -based polyimides, the 3DAC -based polyimides exhibited lower glass transition temperatures and higher photocrosslinking rates of the carbon–carbon double bond as well as higher photosensitivities obtained from the exposure characteristic curves, suggesting that an increase in the photoreactivity of the 3DAC -based polyimides might arise from the improved flexibility of their backbones. The polyimide from 3DAC and 6FDA (2,2-bis[3,4-dicarboxypheny]hexa-fluoropropane dianhydride) showed a photosensitivity of 33 mJ/cm2 with a contrast of 1.5 upon light irradiation using a Xenon lamp. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 685–693, 1998 相似文献
998.
999.
Yanisa Mittraphab Yhiya Amen Maki Nagata Masako Matsumoto Dongmei Wang Kuniyoshi Shimizu 《Molecules (Basel, Switzerland)》2022,27(2)
The extract from Entada phaseoloides was employed as active ingredients of natural origin into cosmetic products, while the components analysis was barely reported. Using LC-DAD-MS/qTOF analysis, eleven compounds (1–11) were proposed or identified from acetone extract of E. phaseoloides leaves (AE). Among them, six phenolic compounds, protocatechuic acid (2), 4-hydroxybenzoic acid (3), luteolin-7-O-β-d-glucoside (5), cirsimaritin (6), dihydrokaempferol (9), and apigenin (10), were isolated by various chromatographic techniques. Protocatechuic acid (2), epicatechin (4), and kaempferol (11) at a concentration 100 μM increased the HaCaT cells viability of the UVB-irradiated cell without any cytotoxicity effect and reduced the expression of COX-2 and iNOS inflammation gene. Moreover, compounds 2 and 4 could have potent effects on cell migration during wound closure. These results suggest that compounds 2, 4, and 11 from AE have anti-photoaging properties and could be employed in pharmaceutical and cosmeceutical products. 相似文献
1000.
Matsumoto Takashi Yamano Akihito Sato Takashi Ferrara Joseph D. White Fraser J. Meyer Mathias 《Journal of chemical crystallography》2021,51(3):438-450
Journal of Chemical Crystallography - The structure of organic compounds, including their absolute configuration, is extremely critical to the activity of medicines, aroma chemicals, and... 相似文献