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901.
Hiroyuki Kono Shin Kawano Tomoki Erata Mitsuo Takai 《Journal of carbohydrate chemistry》2013,32(2):127-140
ABSTRACT A new β-glucosidase, which was partially purified from Trichoderma viride cellulase, catalyzed a transglycosylation reaction of cellobiose to give β-D-Glcp-(1→6)-β-D-Glcp-(1→4)-D-Glcp 1 and β-D-Glcp-(1→6)-β-D-Glcp-(1→6)-β-D-Glcp-(1→4)-D-Glcp 2, regioselectively. Furthermore, the enzyme converted laminaribiose and gentiobiose into β-D-Glcp-(1→6)-β-D-Glcp-(1→3)-D-Glcp 3 and β-D-Glcp-(1→6)-β-D-Glcp-(1→6)-D-Glcp 4, respectively. Selective β-(1→6) transglycosylation was achieved. 相似文献
902.
903.
904.
Takehiro Watanabe Keisuke Nakanishi Tomoyuki Ozawa Hideya Kawasaki Koichi Ute Ryuichi Arakawa 《Rapid communications in mass spectrometry : RCM》2010,24(13):1835-1841
We have designed a semi‐online liquid chromatography/matrix‐assisted laser desorption/ionization mass spectrometry (LC/MALDI‐MS) system to introduce eluent from a octadecylsilyl (ODS) group modified monolithic silica capillary chromatographic column directly onto a sample plate for MALDI‐MS analysis. Our novel semi‐online system is useful for rapidly and sensitively examining the performance of a monolithic capillary column. An additional advantage is the small elution volume of a monolithic capillary column, which allows delicate eluents, such as 1,1,1,3,3,3,‐hexafluoroisopropyl alcohol (HFIP), to be used to achieve cost‐effective analysis. Using the semi‐online LC/MALDI‐MS system, chromatographic separation of polymers by the monolithic column with different eluents was studied. Separation of poly(methyl methacrylate) and Nylon 6/6 showed that the column functioned via size‐exclusion separation when tetrahydrofuran or HFIP eluent was used. On the other hand, the separation behavior of Nylon 11 indicated a reversed‐phase mode owing to the interaction of the polymer with the modified ODS group in the column. Using tetrahydrofuran/methanol (1:1, v/v) as the eluent, the LC/MALDI‐MS spectra of poly(lactic acid), which contains both linear and cyclic polymer structures, showed that the column could separate the hydrophobic cyclic polymer and elute it out relatively slowly. The monolithic column functions basically via size‐exclusion separation; the reversed‐phase separation by interaction with the ODS functions may have less influence on column separation. The semi‐online monolithic capillary LC/MALDI‐MS method we have developed should provide a means of effectively analyzing synthetic polymers. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
905.
T Kurtán N Nesnas Y Q Li X Huang K Nakanishi N Berova 《Journal of the American Chemical Society》2001,123(25):5962-5973
A general microscale protocol for the determination of absolute configurations of primary amino groups or secondary hydroxyl groups linked to a single stereogenic center is described. The chiral substrates are linked to the achiral trifunctional bidentate carrier molecule (3-aminopropylamino)acetic acid (1, H(2)NCH(2)CH(2)CH(2)NHCH(2)COOH) and the resultant conjugates are then complexed with dimeric zinc porphyrin host 2 giving rise to 1:1 host/guest sandwiched complexes. These complexes exhibit exciton-coupled bisignate CD spectra due to stereodifferentiation leading to preferred porphyrin helicity. Since the chiral sense of twist between the two porphyrins in the complex is dictated by the stereogenic center of the substrate, the sign of the couplet determines the absolute configuration at this center. The twist of the porphyrin tweezer in the complex can be predicted from the relative steric sizes of the groups flanking the stereogenic center, such that the bulkier group protrudes from the complex sandwich. In certain alpha-hydroxy esters and alpha-amino esters, electronic factors and hydrogen bonding govern the preferred conformation of the complex, and hence the CD spectra. 相似文献
906.
S Wakida A Chiba T Matsuda K Fukushi H Nakanishi X Wu H Nagai S Kurosawa S Takeda 《Electrophoresis》2001,22(16):3505-3508
To evaluate organic pollution in water, we did preliminarily studies on high-throughput characterization of organic pollution in water using microchip-based capillary electrophoresis (CE) with laseer-induced fluorescence (LIF) detection. The applied voltage was investigated to control the gated valve injection and CE separation for conventional cross type microchips using a self-made personal computer (PC)-based controller as the voltage supply. We obtained high-throughput data for the reproducible separation of fluorescein isothiocyanate (FITC)-labeled river-water samples using a zwitter-ion based buffer solution to avoid adsorption of the labeled sample onto the channel of a microchip made from quartz glass. We used real samples from the Hino River that flows into Lake Biwa, from ten sampling points and obtained several reproducible peaks in different separation patterns for each sample within 2 min. We successfully demonstrated high-throughput characterization of dissolved organic carbon (DOC) in environmental water using the microchip. 相似文献
907.
T. M. Nakanishi 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(2):469-473
We present Na, Mg, Al, K and Ca profiles, determined by neutron activationanalysis (NAA) in a soybean plant during its life cycle in water culture.The concentrations of Mg and Ca in leaves were higher than the other tissuesduring the developmental stage of a plant. The concentration of K was relativelyuniform within a plant. When a plant was treated with V, element uptake amount,especially Mg, K and Ca, was decreased throughout the life cycle. Vanadiumtreatment also induced low concentration of Mg and K in roots. 相似文献
908.
Effect of host crystallinity on lithium extraction/insertion of LiMn2O4 was studied. LiMn2O4 powders with different crystallinity were prepared via lithium-manganese-tartrates by heat treatment at various temperatures above 300 °C. First charge-discharge capacity around 4 V depended on lattice parameter a0 and lattice strain . On the other hand, the first discharge capacity around 3 V was found to be independent of these parameters. 相似文献
909.
Tomoki Yamashita 《Journal of Graph Theory》2007,54(4):277-283
For a graph G, we denote by dG(x) and κ(G) the degree of a vertex x in G and the connectivity of G, respectively. In this article, we show that if G is a 3‐connected graph of order n such that dG(x) + dG(y) + dG(z) ≥ d for every independent set {x, y, z}, then G contains a cycle of length at least min{d ? κ(G), n}. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 277–283, 2007 相似文献
910.
Akio Nakanishi 《Radiation measurements》1994,23(2-3)
The terrestrial ages of Antarctic meteorites were estimated from the thermoluminescence (TL) intensity of the fusion crust. It was found that there is a good correlation between the TL intensities and terrestrial ages which had been previously determined by cosmogenic radionuclide abundance. 相似文献