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71.
Shin-ichi Nakakita Kayo Hasehira Tomohiro Hosokawa Masaaki Tokuda Ken Izumori Kaoru Takegawa Jun Hirabayashi 《Journal of chromatography. A》2009,1216(26):5112-5115
A rare sugar is considered to be a monosaccharide rarely found in nature. To investigate their natural distribution and biological roles, a robust analytical system must be used to isolate, identify, and quantify them. Herein, we report the development of such a system that can specifically quantify and chromatographically separate four aldopentoses and eight aldohexoses tagged with 2-aminopyridine. Purified monosaccharides derivatized with a pyridylamino moiety (PA–monosaccharides) are first chromatographed over a high-performance anion-exchange resin. But, because two of the PA–aldohexoses used in this study, PA–talose and PA–idose, co-elute with the common saccharides, PA–glucose and PA–mannose, respectively, a second chromatographic step, reversed-phase high-performance liquid chromatography, is used to completely separate them. Thus, as shown by the results of this study, chromatographic separation of PA–monosaccharides is achievable and provides a quantitative measurement of common and rare isomeric aldopentoses and aldohexoses. 相似文献
72.
Masashi Haruki Fumiya Kobayashi Kazuya Kishimoto Shin-ichi Kihara Shigeki Takishima 《Fluid Phase Equilibria》2009,280(1-2):49-55
A new apparatus based on the circulation method was developed to measure the solubility of metal complexes in supercritical carbon dioxide (scCO2) at a wide range of temperatures and pressures. A UV–vis spectrometer, which was connected to a small saturation cell through optical fibers, was used to determine solubility. The solubilities of cobalt(III) acetylacetonate (Co(acac)3) and chromium(III) acetylacetonate (Cr(acac)3) in scCO2 were measured to check the validity of both the apparatus and the method and to accumulate new solubility data. The solubility data for Cr(acac)3 obtained in this study were in good agreement with the data reported in the literature.The measured solubilities of Co(acac)3 and Cr(acac)3 were also correlated with the empirical equation including the three adjustable parameters, based on the equation proposed by Chrastil. The parameters were determined by fitting the equation to the experimental data for each metal complex and the calculated results closely replicated the experimental data. 相似文献
73.
Tatsuya Suzuki Yasuhiko Fujii Wu Yan Hitoshi Mimura Shin-ichi Koyama Masaki Ozawa 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):641-644
We investigated the adsorption behaviors of technetium and rhenium on tertiary pyridine resin in hydrochloric acid solution.
Technetium has a little larger distribution coefficient in higher concentration of hydrochloric acid region than rhenium.
However, the tendency of adsorption behavior of technetium and rhenium is similar. We concluded that the rhenium can be used
as the substitute for technetium. Adsorption behaviors of platinum group elements were also investigated. The separation of
technetium from platinum group elements is discussed. 相似文献
74.
We study relations between induced subgraphs and (n,m)-subposets. Using properties of (n,m)-subposets, we consider a characterization of chordal double bound graphs in terms of forbidden subposets. Furthermore, we deal with properties of a poset whose double bound graph is isomorphic to its upper bound graph or its comparability graph, etc. 相似文献
75.
Total synthesis of fumitremorgin B 总被引:2,自引:0,他引:2
Total synthesis of fumitremorgin B, one of the potent tremorgic mycotoxins, was achieved in 7 steps. 相似文献
76.
Hiroshi Oki Ichiro Oura Tatsuhito Nakamura Kenichi Ogata Shin-ichi Fukuzawa 《Tetrahedron: Asymmetry》2009,20(18):2185-2191
A series of diphosphine ClickFerrophos ligands (CF), based on a triazoleferrocene backbone, was synthesized in a four-step sequence via click chemistry methodology. In addition to the four previously synthesized ligands CF1, CF4, CF7 and CF10, six novel CF ligands CF2–3 and CF5–8 were prepared. Hydrogenation reactions of alkenes and ketones were significantly improved upon by using CF ligands as rhodium- or ruthenium-complexes in which the % ee values can be optimized by choosing the appropriate CF ligand depending on the substrate. 相似文献
77.
Hiroki Hotta Kazuya Tatsuno Yoji Hattori Takuya Hashimoto Masayuki Uehara Kin-ichi Tsunoda 《Electrochemistry communications》2008,10(9):1351-1354
The H+ concentration change was monitored near an electrode surface through an electrolysis using a slab optical waveguide technique. Indium tin oxide transparent electrode modified by porous insulating polymer to which methyl red was covalently immobilized was used as a guiding layer, and the absorbance change of the polymer film was monitored. H+ generation at the vicinity of the electrode through the oxidation of ascorbic acid could be monitored by this technique. 相似文献
78.
79.
Takuya Hasegawa Tomonari Umemura Akira Koide Koichi Chiba Yuji Ueki Kin-ichi Tsunoda Hiroki Haraguchi 《Analytical sciences》2005,21(8):913-916
An octadecylsilica (ODS) column modified with zwitterionic/nonionic mixed surfactants was evaluated for the direct injection determination of inorganic anions in biological fluids by ion chromatography. A zwitterionic surfactant (sulfobetaine-type) and a nonionic surfactant (polyoxyethylene-type) were used for a stationary-phase modification. When aqueous electrolyte solutions with concentrations of sub-mM to several mM were used as a mobile phase, the zwitterionic surfactant coated on the ODS surface exhibited unique separation selectivity for ionic species, while the nonionic surfactant coated on the ODS might have formed a hydrophilic network over the ODS surface and restricted matrix proteins from adsorbing on the stationary phase. Consequently, the mixed surfactant-modified column system allowed an efficient ion chromatographic separation of inorganic anions as well as a size-exclusive removal of column-fouling proteins. This separation system was applied to the direct injection determination of UV-absorbing anions in human saliva. The detection limits for nitrite, nitrate, iodide and thiocyanate were 3.1, 2.7, 4.5 and 25 microM, respectively, with UV detection at 210 nm (injection volume; 20 microl), and their relative standard deviations for 5 replicate measurements of saliva samples spiked with 100 microM each of those anions were 1.4, 0.9, 2.2 and 5.5%, respectively. 相似文献
80.
Yoshimasa Makita Tomofumi Danno Keisuke Ikeda Hsien-Han Lee Taro Abe Kento Sogawa Akihiro Nomoto Shin-ichi Fujiwara Akiya Ogawa 《Tetrahedron letters》2017,58(48):4507-4509
Hemicryptophanes are covalent molecular cages, constructed from a cyclotriveratrylene-based host unit and a functional unit linked by covalent spacers, which have been designed to accommodate endohedral functionalities in the cavity. In this study, the synthesis and characterization of the rigid, biphenyl-linked hemicryptophane 1 were investigated by NMR, ESI-MS, and X-ray crystallography. The structure of the inclusion complex, in which a dichloromethane molecule was constructed encapsulated within 1, was characterized by X-ray crystallography. An endohedral, cobalt(II) hemicryptophane complex 2 was also synthesized and characterized ESI-MS and X-ray crystallography. The X-ray crystal structure of 2 showed that the biphenyl-linked hemicryptophane had three components—a molecule each of chloroform and acetonitrile, and a cobalt(II) ion—within its cavity. 相似文献