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61.
A novel method for determination of inorganic oxyanions by electrospray ionization mass spectrometry using dehydration reactions
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Hirochika Kojima Shota Kurihara Yoshito Watanabe Koki Iwamaru Kiichi Sato Kin‐ichi Tsunoda Hiroki Hotta 《Journal of mass spectrometry : JMS》2016,51(2):123-131
Novel methods for the determination of inorganic oxyanions by electrospray (ES) ionization mass spectrometry have been developed using dehydration reactions between oxyanions and carboxylic acids at the ES interface. Twelve oxyanions (VO3?, CrO42?, MoO42?, WO42?, BO33?, SiO32?, SiO44?, AsO44?, AsO2?, SeO42?, SeO32? and NO2?), out of 16 tested, reacted with at least one of four aminopolycarboxylic acids, i.e. iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), trans‐1,2‐diaminocyclohexane‐N,N,N′,N′‐tetraacetic acid and triethylenetetramine‐N,N,N′,N″,N′″,N′″‐hexaacetic acid, at the ES interface to produce the dehydration products that gave intense mass ion responses, sufficient for trace analysis. As examples, trace determinations of CrVI and silica in water samples were achieved after online ion exchange chromatography, where the dehydration product of CrO42? and NTA (m/z 290) and that of SiO44? and IDA (m/z 192) were measured. The limits of detection of the respective methods were 17 nM (0.83 ng Cr/ml) for CrVI and 0.17 μM (4.8 ng Si/mL) for SiO44?. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
62.
Green organogelators with a sulfide linkage and free amino groups were synthesized via phase transfer catalysis using a N-benzylcinchonidinium bromide catalyst. Their self-assemblies in various common solvents were examined. These compounds exhibit high gelation ability especially in aromatic and highly polar solvents with a low critical gelation of 0.1 wt %. The organogels were analyzed by 1H nuclear magnetic resonance (1H NMR) and Fourier transfer-infrared spectroscopies (FT-IR), and their phase transition temperatures were determined by differential scanning calorimetry. The homogeneity of the gel networks was examined by field emission scanning electron microscopy and transmission electron microscopy (TEM). A lamellar structure was also confirmed by X-ray diffraction analysis. The organogels were employed as soft-templates for the in situ generation of stable gold nanoparticles dispersed in the gel matrix, and the resulting GNP dispersions were studied by 1H NMR and UV–vis absorption. Transmission electron microscopy showed that GNPs assemble into a thin membrane-like structure. 相似文献
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64.
Bungo Ochiai Haruka Kojima Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(8):1113-1118
Polyhydroxyurethane bearing silicone backbone was prepared by polyaddition of silicone diamines with a bifunctional five‐membered cyclic carbonate prepared from the corresponding diepoxide and CO2. Polymerization in propylene glycol methyl ether acetate proceeded smoothly, and polymers could be obtained in high yields under appropriate conditions. The introduced silicone moieties improved the hydrophobicity and lowered the glass transition temperature keeping thermal stability. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1113–1118 相似文献
65.
Yusuke Nakajima Takeshi Kawano Yusuke Taki Chie Kojima 《Research on Chemical Intermediates》2018,44(8):4745-4754
Collagen is a major component of the extracellular matrix, and collagen gels have been used as cell scaffolds. We previously prepared gold nanoparticle (AuNP)-embedded collagen gels (AuCol) to serve as cell scaffolds that were sensitive to visible light. We performed single cell detachment from this cell scaffold using a microscope equipped with a laser irradiation system. In the present study, we adjusted hydrogel thickness and AuNP concentration in AuCol, with a goal of improving cell detachment efficiency. Thin hydrogels became blackened after the laser irradiation, and thick hydrogels with high AuNP concentrations were not permeable to the laser light. We, therefore, prepared bilayer gels, composed of AuCol as the upper layer and intact collagen gel (Col) as the bottom layer. These bilayer gels allowed more effective cell detachment, because they were thick and optically transparent. Our results indicated that an AuCol/Col ratio of 2 enabled the highest cell detachment efficiency. Essentially, no cell damage was observed in our system, suggesting that this is a cell-friendly single cell separation system. 相似文献
66.
Kentaro Okuma Kazuki Kojima Kosei Shioji 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):583-586
Reactions of selenobenzophenones with methyl propiolate afforded two types of cycloadducts regioselectively. The reaction with tetracyanoethylene gave selenophene derivatives. Mechanisms of these reactions were discussed. 相似文献
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68.
Tohru TakeiTakumi Ohki Yosuke HaradaNaoto Kumagai Hiroki FukumotoTake-aki Koizumi Akihiro MaedaTakahiro Kojima Yoshihisa SeiKohei Shiramizu Masahiro AbeMasashi Oota Takakazu Yamamoto 《Tetrahedron letters》2012,53(44):5907-5910
Dibromopyridines or dibromopyridone with -(CH2)m-SO3Na group(s) has been prepared via the reactions of the corresponding dibromopyridines with -OH and -NH2 groups with sultone. These compounds were converted into polymers with the -(CH2)m-SO3H groups via organometallic polycondensation. The polymer showed proton conducting properties and high stability toward oxidation. 相似文献
69.
The effect of amines on the selective bromination of some β-substituted-2-butenoic esters is described. The bromination of methyl (Z)-4-t-butyldiphenylsilyloxy-3-methylbutenoate 2 in the presence of DIPEA (N, N-diisopropylethylamine) and the successive treatment of the obtained dibromide with potassium t-butoxide afford the desired Z bromide selectively. But the corresponding E bromide forms exclusively when 2, 6-di-t-butyl-4-methylpyridine is used in the bromination. 相似文献
70.
Novel chiral bisformamides have been prepared from (R,R)-1,2-cyclohexanediamine and utilized as Lewis bases in the asymmetric allylation of benzaldehyde with allyltrichlorosilane. The reaction in the presence of Lewis base 1i gave an 83:17 enantiomeric ratio (R/S) of the products in 90% isolated yield. 相似文献