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排序方式: 共有117条查询结果,搜索用时 31 毫秒
31.
Yuko Ikeda Youichi Kurokawa Koji Nakane Nobuo Ogata 《Cellulose (London, England)》2002,9(3-4):369-379
We developed a new entrap-immobilization method, using a gel formationof cellulose acetate and metal (Ti, Zr) alkoxide. Several biocatalysts(-galactosidase, -chymotrypsine, invertase, urease, lipase andSaccharomyces cereviciae) were successfullyentrap-immobilized on this composite gel fiber. The immobilization process wassimple and the resultant immobilized biocatalysts on the gel fiber were easy tohandle. It is considered that the biocatalysts are physically entrapped amongthe gel networks and distribute throughout the gel fiber. The gel fiber wasstable in phosphate buffer solution, electrolyte solution and organic solvent,because the gel formation was due to coordination interaction between celluloseand transition metal. Therefore, it can be applicable as a support for abiotransformation in various reaction media. We examined some enzyme reactionsand biotransformation using the immobilized biocatalysts on this gel fiber andevaluated this immobilization matrix in the reactions compared to the resultsobtained by the other immobilization method. The immobilized biocatalyst showedstable activity for repeated cycles and over a long period of time. Moreover,continuous reaction could be carried out in a column reactor packed with thisimmobilized biocatalyst. 相似文献
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33.
The low work-function ZrO/W(100) surface was examined with the aim of understanding the reducing mechanism of the work function. Low-energy electron diffraction (LEED) was employed to analyze the surface atomic arrangement, and X-ray photoelectron spectroscopy (XPS) was used to identify the surface chemical condition. The ZrO/W(100) surface was made as follows: (i) around three monolayers of Zr were deposited on a clean W(100) surface, (ii) the sample was heat treated in an oxygen ambience of 1.3x10−5 Pa for several tens of minutes at 1500 K, and (iii) the sample was flash heated at 2000 K in ultrahigh vacuum (UHV). During heat treatment in O2, the deposited Zr was oxidized to ZrO2, and the LEED pattern formed was p(2×1). The work function increased to 5.3 eV. Subsequent flash heating in UHV changed the p(2×1) LEED pattern into a c(4×2) pattern, and transformed ZrO2 into the so-called Zr–O complex, the oxidized level of which is between ZrO2 and metallic Zr. A drastic decrease in the work function to 2.7 eV ensued. The angular dependence of XPS showed that the Zr–O complex segregated within a few monolayers at the surface. 相似文献
34.
Kazunori Matsumura Kikuko Hayamizu Takashi Nakane Hiroshi Yanagishita Osamu Yamamoto 《Journal of Polymer Science.Polymer Physics》1987,25(10):2149-2163
1H- and 2H-NMR spectra of H2O and D2O absorbed in cellulose acetate films were observed while changing the angle between the plane of the film and the magnetic field. 1H-NMR spectra show dipolar splittings that vary depending on the angle. The splitting has a maximum when the surface of the film is perpendicular to the magnetic field. From the angular dependence of the dipolar splitting, it is recognized that the proton-proton dipolar axis of water molecules tends to orient perpendicularly to the surface of the film. 2H-NMR spectra that show quadrupolar splittings also indicate that the quadrupolar axis tends to orient perpendicularly to the film. The so-called bound water and free water in the film can exchange rapidly on the NMR time scale, so that the line width and the splitting of the NMR spectra become smaller as the amount of water in the film increases. From the temperature dependence of line widths, the apparent reorientational activation energy of water molecules in the film is estimated to be 25 kJ/mol from 1H-NMR and 31 kJ/mol from 2H-NMR. 相似文献
35.
K Hirota H Hosono Y Kitade Y Maki C K Chu R F Schinazi H Nakane K Ono 《Chemical & pharmaceutical bulletin》1990,38(9):2597-2601
36.
Degradation of liposome cluster caused by the interaction with endocrine disrupting chemicals (EDCs)
The interaction between endocrine disrupting chemicals (EDCs) and liposome clusters was investigated using UV-vis spectroscopy and observed by microscope. Since liposome clusters are composed of small unilamellar liposomes and membrane proteins, they are regarded as a model of plasma membranes. The size of each cluster was 10microm in diameter. UV-vis spectroscopy of liposome clusters showed an apparent absorption at 300nm which was affected by the interaction with EDCs. Four EDCs caused an alteration in absorption in a concentration-dependence manner between 0.1 and 10ppm (i.e. 0.1-10mg/l). Microscopic observation showed that the effect was caused by the degradation of liposome clusters while degradation was induced by the interaction; liposome was broken down by EDCs. This report suggests that the liposome cluster can be applied for universal detection of EDCs based on the interaction between a plasma membrane model and EDCs. 相似文献
37.
Kuroyanagi M Ikeda R Gao HY Muto N Otaki K Sano T Kawahara N Nakane T 《Chemical & pharmaceutical bulletin》2008,56(1):60-63
In the screening of biologically active constituents from woody plants, the methanol extract of leaves of Chamaecyparis obtusa showed potent neurite outgrowth-promoting activity in neuronal PC12 cells. The ethyl acetate-soluble fraction of the methanol extract showed potent activity and was separated by means of various chromatographic methods to give the two new compounds 1 and 2, as well as 11 known lignan and sesquiterpene derivatives. The structures of the new compounds were determined to be 9-O-acetyldihydrosesamin (1) and 9-O-(11-hydroxyeudesman-4-yl)dihydrosesamin (2), respectively, in NMR studies including 2D-NMR experiments. Of the 13 compounds, the known compound hinokinin (5) and the new compound 2 showed potent neurite outgrowth-promoting activity in PC 12 cells. 相似文献
38.
Ushijima M Komoto N Sugizono Y Mizuno I Sumihiro M Ichikawa M Hayama M Kawahara N Nakane T Shirota O Sekita S Kuroyanagi M 《Chemical & pharmaceutical bulletin》2008,56(3):308-314
In the course of the development of new designer foods using the roots of Codonopsis lanceolata, we found that hot-water extracts of C. lanceolata recovered decreased testosterone levels in the blood and accelerated the restoration of reproductive dysfunction induced by hyperthermic treatment in male mice. Thus we studied the constituents of the polar fraction of the roots of C. lanceolata and identified six new triterpene saponins, lancemasides B (2), C (3), D (4), E (5), F (6), and G (7), along with the known saponin lancemasaide A (1) and phenylpropanoid glycosides 8-10. The structures of the new compounds 2-7 were determined by means of spectral data including 2D-NMR studies and chemical reactions to be oleanan-type bisdesmoside with sugars at C-3 and C-28. Compounds 2-6 have echinocystic acid as an aglycone, and compound 7 has asterogenic acid as an aglycone. Identification of the sugars and determination of their D,L-chiralities were carried out by application of the exciton chirality method to the per-O-p-bromobenzoylmethyl sugar derived from saponins. 相似文献
39.
Gao HY Wu LJ Muto N Fuchino H Nakane T Shirota O Sano T Kuroyanagi M 《Chemical & pharmaceutical bulletin》2008,56(7):1030-1034
In the course of studies on biological active constituents from woody plants, we previously reported the isolation of many lignan derivatives as neurite outgrowth-promoting compounds from an ethyl acetate soluble fraction of Japanese Cypress (Chamaecyparis obtusa). Further chemical investigation on the residual parts of the ethyl acetate soluble fraction of a methanol extract of Japanese Cypress resulted in the isolation of four new beyerene type derivatives and a novel sesquiterpene dimer formed between cryptomeridiol and hinokiic acid. Their structures were elucidated as 18-O-(Z)-p-coumaroylbeyer-15-ene-18-ol (1), 18-O-(E)-p-coumaroylbeyer-15-ene-18-ol (2), 18-O-(E)-p-coumaroylbeyer-15-ene-11beta,18-diol (3), 18-O-(Z)-p-coumaroylbeyer-15-ene-11beta,18-diol (4) and ent-cryptomeridiol-4-yl-hinokiiate (5) by (1)H-NMR, (13)C-NMR, 2D-NMR, and HR-MS spectral analysis. 相似文献
40.