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141.
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143.
Temperature gradient interaction chromatography (TGIC) is applied to the characterization of polyisoprene (PI) and polystyrene (PS) using normal-phase (NP) stationary phase--bare silica or diol bonded silica. Tetrahydrofuran-isooctane mixtures are used as a mobile phase. PI and linear and star shaped PS samples are successfully fractionated in terms of the molecular mass with a high resolution comparable to that of reversed-phase (RP) HPLC. Temperature dependence of the retention shows that the enthalpy of adsorption of PS to the stationary phase is exothermic. In addition, some characteristic features of the NP-TGIC system relative to those of RP-TGIC are presented, which include a high sensitivity on the polar end group and the simultaneous size-exclusion chromatographic and TGIC characterization of PS and PI mixtures. 相似文献
144.
Owen S. Jeong B. C. Poole P. S. Macaskie L. E. 《Applied biochemistry and biotechnology》1992,(1):693-707
Tributyl phosphate (TBP), a plasticizer and solvent, is used in nuclear fuel reprocessing, generating TBP wastes laden with
residual uranium. ACitrobacter sp. accumulated heavy metals via a phosphohydrolase(s) that precipitated metals with inorganic phosphate liberated from an
organic phosphate “donor” molecule (TBP). Mutant analysis suggested that TBP hydrolysis was not attributable to a previously
documented acid phosphatase (monoesterase). Purified monoesterase had little activity against phospho di- and triesters, had
no requirement for Mg2+ or Mn2+, and was EDTA-resistant. Conversely, TBP cleavage by immobilized cells was enhanced by Mg2+, and ininhibited by Mn2+ and EDTA. A separate phosphotri/diesterase was implicated. 相似文献
145.
Kang EJ Cho EJ Ji MK Lee YE Shin DM Choi SY Chung YK Kim JS Kim HJ Lee SG Lah MS Lee E 《The Journal of organic chemistry》2005,70(16):6321-6329
(+)-SCH 351448 (Na+ salt A) was synthesized employing ring-closing olefin metathesis reaction of an open diene diester intermediate for construction of the 28-membered macrodiolide structure. The open diene diester was prepared from the monomeric hydroxy carboxylic acid and two different olefin fragments. The monomeric hydroxy acid was synthesized via Julia-Julia coupling reaction of intermediates derived from the same olefinic fragments. Oxane units in these fragments were prepared by radical cyclization reactions of beta-alkoxyacrylates. Analogous SCH 351448 salts incorporating other mono- and divalent cations may be prepared. Under acidic conditions, SCH 351448 (Na+ salt A) was the most stable complex, but SCH 351448 (Ca2+ salt) and (Na+ salt B) appear to be physiologically important species. 相似文献
146.
Competitive binding of a Tris run buffer with chiral crown ether in chiral capillary electrophoresis
In capillary electrophoresis of primary amine racemates using (+)-(18-crown-6)-tetracarboxylic acid (18C6H4) as a chiral selector, chiral recognition emanates from the differences in the complex formation between 18C6H4 and the two protonated amine enantiomers. The presence of buffer constituents such as tris(hydroxymethyl)aminomethane (Tris) or Na+, capable of forming complexes with 18C6H4, is thus detrimental to the chiral separation of primary amines. Such a competitive binding of buffer constituents was studied by comparing the electrophoretic mobilities of racemic analytes obtained in Tris/citric acid and triethylamine/citric acid buffers. We developed a simple fitting method to determine the competitive binding constant and applied it to the Tris buffer system. The competitive binding constant of Tris with 18C6H4 obtained at pH 3.0 was 27 +/- 4. 相似文献
147.
Sang Chul Shim Chil Hoon Doh Tae Jeong Kim Hak Ki Lee Ki Doo Kim 《Journal of heterocyclic chemistry》1988,25(5):1383-1385
Ethanolic tetracarbonylhydridoferrate combined with adipaldehyde is very efficient for the selective transformation of an amino group into perhydroazepine. A large variety of both aliphatic and aromatic amines react with adipaldehyde in the presence of tetracarbonylhydridoferrate at room temperature and carbon monoxide to give the corresponding N-alkyl- and N-arylperhydroazepines in good to excellent yields. 相似文献
148.
Turner syndrome is one of the most common cytogenetic abnormalities. It is known that the Y chromosome or Y derived material is present in 6-9% of TS patient and it may develop a high risk of gonadoblastoma in 15-25%. So it is crucial to carry out cyto genetic analysis and Y-specific probe studies for all persons with gonadal dysgenesis to rule out mosaicism with Y-bearing cell line; eg 45,X/46,XY. In this study, 26 archival slides previously analyzed cytogenetically as 45,X, 45,X/46,X,i(X), 45,X/46,X,r(X), and 45,X/46,XX were examined. Coamplification PCR, having the advantage of providing rapid result and confirming PCR failure, was performed with the slide samples in the regions of dystrophin gene in Xp21and DYZ3 in the Y centromeric region. All of archived slides were positive for X-specific gene and one slide of 45,X was found to have the cryptic Y chromosome material. Our result suggests that the archived cytogenetic slides could be applied for the detection of Y chromosome rapidly and efficiently in TS patients. 相似文献
149.
2-Iodoaniline reacts with α,β-unsaturated carbonyl compounds in DMF at 100 °C in the presence of a catalytic amount of a palladium catalyst along with a base to afford the corresponding quinolones or quinolines in moderate to good yields. 相似文献
150.
Jae Ha Kim Young Tae Jeong Seong Ihl Woo 《Journal of polymer science. Part A, Polymer chemistry》1994,32(15):2979-2987
Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl2/ToCl4 complex with or without high surface area silica. Copolymerization of ethylene and 1-butene has been tested by using the prepared catalysts at various concentrations of 1-butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1-butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio (k11) for TiCl4/MgCl2/THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc. 相似文献