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71.
Kiyoshi Shibata Hiroshi Kimura Akira Tsuchida Tsuneo Okubo Shohei Sato Kohji Yoshinaga 《Colloid and polymer science》2006,284(4):372-379
Electro-optic responses of colloidal crystals consist of poly(maleic anhydride-co-styrene)-modified silica spheres (P(MA-ST)/SiO2) in acetonitrile and the crystals immobilized with a gelator, N-benzyloxycarbonyl-L-isoleucilaminooctadecane (Z-L-Ile-C-18), are studied by reflected-light intensity measurements and time-resolved reflection spectroscopy. Application of
an alternating electric field deforms P(MA-ST)/SiO2 crystal lattices reversibly. The response waveforms from the crystals are dependent on the frequency and strength of the
applied electric field; similar dependencies have been qualitatively observed for the colloidal crystals consisting of polystyrene
or silica spheres in aqueous media in our previous studies. Both gelated and ungelated P(MA-ST)/SiO2 crystals change the reflection intensity, however, the amplitude is larger for the latter. The small response for the gelated
P(MA-ST)/SiO2 crystals is attributed to the higher elastic modulus (G). The G value of the gelated P(MA-ST)/SiO2 crystals in acetonitrile is estimated from the change in the inter-sphere distance to be 8.0 Pa, which is about 2.3 and 2.4
times larger than that for ungelated P(MA-ST)/SiO2 crystals in acetonitrile and colloidal silica crystals in aqueous media, respectively. 相似文献
72.
73.
Biological reference materials for elemental speciation were prepared at the National Institute for Environmental Studies. A new human hair reference material, prepared by cryogenic grinding using a ceramic disc mill, is in the process of certification for methyl-Hg and trace elements. Hijiki seaweed reference material was prepared for As speciation studies, primarily for use in the analysis of As(V). Scallop tissue reference material will be certified for arsenobetaine. 相似文献
74.
Cheng-yuan Huang Ning Wang Katsumasa Fujiki Yuji Otsuka Masao Akamatsu Yukari Fujimoto 《Journal of carbohydrate chemistry》2013,32(6):289-298
The N-Troc (2,2,2-trichloroethoxycarbonyl) groups in glucosamine and muramic acid derivatives were removed by treatment with tetrabutylammonium fluoride (TBAF) under mild conditions. The use of Troc protection for the amino group in aminosugars such as glucosamine is increasing the importance for selective and efficient glycosylation, and the cleavage method described here will expand the available opportunities for using the Troc group in the preparation of a variety of glycans. This cleavage is especially advantageous for compounds that are labile or may be decomposed under acidic conditions, strong basic conditions, or reductive conditions. 相似文献
75.
Tatsuro Yoshinaga Takumi Fujiwara Dr. Takayuki Iwata Prof. Dr. Mitsuru Shindo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(61):13855-13859
1,8,13-Trialkyl(aryl)silyl-9-hydroxytriptycenes (trisilyltriptycenes) were synthesized by the triple addition of ynolates and 3-silylbenzynes with high regioselectivity. Benzene rings in the resulting triptycenes were highly distorted where the dihedral angles between the substituents were as high as 35°. The distortion energy induced step-by-step halogenation reactions to yield halogenated triptycenes, including chiral triptycenes. The 1,8,13-trihalogenated triptycenes were then converted to 1,8,13-functionalized triptycenes. 相似文献
76.
Yosuke Uchinashi Katsunori Tanaka Yoshiyuki Manabe Yukari Fujimoto 《Journal of carbohydrate chemistry》2013,32(2):55-67
Efficient α-sialylation with a C5 azide sialyl donor was investigated under microfluidic conditions using a microreactor composed of a Comet X-01 micromixer and a tube reactor. Precise temperature control realized excellent α-selectivity, and Siaα(2,6)Gal, Siaα(2,3)Gal, and Siaα(2,9)Sia disaccharides were obtained in moderate to good yields. 相似文献
77.
Takao Okada Yukari Imamura Takehisa Matsuda 《Journal of polymer science. Part A, Polymer chemistry》2010,48(7):1485-1492
Polymerization of a trimethylene carbonate (TMC) in an aqueous solution was investigated by gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The polymerization reaction proceeded rapidly in the aqueous solution and high conversion was achieved in a relatively short time. 1,3‐Propanediol (PPD) formed by hydrolysis of TMC was used as the initiator. The TMC oligomer obtained by ring‐opening polymerization had a TMC unit backbone with terminal 3‐hydroxypropyl groups at both chain ends. The oligomer underwent transesterification reaction with elimination of PPD, resulting in a gradual increase in the molecular weight of the product. The molecular weight was affected by the concentration of TMC. The thermal properties of the polymers were investigated by differential scanning calorimetry. Polymers within the molecular weight (Mn) range from 6.0 × 103 to 2.3 × 104 g/mol crystallized, and endothermic peaks corresponding to the melting temperature were observed. The glass transition temperature increased with the molecular weight of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1485–1492, 2010 相似文献
78.
Jun Yoshinaga Naoto Matsuo Hideki Imai Minato Nakazawa Tsuguyoshi Suzuki Masatoshi Morita 《International journal of environmental analytical chemistry》2013,93(1-2):27-38
Abstract Elemental concentrations of internal organs (cerebrum, cerebellum, heart, spleen, liver and kidney) of Japanese were measured with inductively coupled plasma mass spectrometry (ICP-MS). Sixty-one elements were determined simultaneously, and concentrations of some trace elements in human organs, on which information are scarcely available in the literature, were obtained. The analytical values obtained by ICP-MS and those by other methods were compared and fairly good agreement was found for Cd, Zn and Fe. Moderate agreement was found for Se and Hg, but discrepancy was observed for Mg and Na. Unacceptable values were obtained for some elements, such as Ti, Sc or Ge, probably due to polyatomic molecular interference. 相似文献
79.
Yu‐Shih Lin Julius S. Lipp Marcos Y. Yoshinaga Shao‐Hsuan Lin Marcus Elvert Kai‐Uwe Hinrichs 《Rapid communications in mass spectrometry : RCM》2010,24(19):2817-2826
Glycolipids are prominent constituents in the membranes of cells from all domains of life. For example, diglycosyl‐glycerol dibiphytanyl glycerol tetraethers (2Gly‐GDGTs) are associated with methanotrophic ANME‐1 archaea and heterotrophic benthic archaea, two archaeal groups of global biogeochemical importance. The hydrophobic biphytane moieties of 2Gly‐GDGTs from these two uncultivated archaeal groups exhibit distinct carbon isotopic compositions. To explore whether the isotopic compositions of the sugar headgroups provide additional information on the metabolism of their producers, we developed a procedure to analyze the δ13C values of glycosidic headgroups. Successful determination was achieved by (1) monitoring the contamination from free sugars during lipid extraction and preparation, (2) optimizing the hydrolytic conditions for glycolipids, and (3) derivatizing the resulting sugars into aldononitrile acetate derivatives, which are stable enough to withstand a subsequent column purification step. First results of δ13C values of sugars cleaved from 2Gly‐GDGTs in two marine sediment samples, one containing predominantly ANME‐1 archaea and the other benthic archaea, were obtained and compared with the δ13C values of the corresponding biphytanes. In both samples the dominant sugar headgroups were enriched in 13C relative to the corresponding major biphytane. This 13C enrichment was significantly larger in the putative major glycolipids from ANME‐1 archaea (~15‰) than in those from benthic archaea (<7‰). This method opens a new analytical window for the examination of carbon isotopic relationships between sugars and lipids in uncultivated organisms. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
80.
Tormena CF Yoshinaga F Doi TR Rittner R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(3):511-517
Conformational preferences and orbital interactions of methyl chloroacetate (1), methyl bromoacetate (2) and methyl iodo-acetate (3) were analyzed using experimental infra-red data, theoretical calculations and NBO analyses. The conformational equilibria of compounds 1-3 can be represented by their cis and gauche rotamers. The gauche form of 1 is stable in the vapour phase and in a non-polar solvent, but the cis is predominant in a polar solvent. For 2 the gauche form is more stable than the cis, in both the vapour and liquid phases, but for compound 3 only the gauche form was observed both in vapour phase as in solution. These conformational preferences were attributed to the orbital interaction between two antibonding orbitals pi(C=O)(*)-->sigma(C-X)(*). This unexpected interaction was possibly due to the high (0.2) electron density on pi(C=O)(*), which results from the interaction between ether oxygen lone pair and pi(C=O)(*). 相似文献