نتایج جستجو برای: borate
تعداد نتایج: 3395 فیلتر نتایج به سال:
Ž Ž . . Ž Ž .y. Dissolved boron in seawater occurs mainly in the form of boric acid B OH and borate B OH . While the 3 4 equilibrium properties of the dissociation of boric acid have been studied in detail, very little work has focused on the kinetics of the boric acid–borate equilibrium in seawater. Here, we present a theoretical study of the relaxation of the w Ž . seawater borate–carbonate s...
The stability of centrifugally purified PR8 influenza virus at pH 7 in 0.001, 0.01, 0.1, and 1.0 M phosphate buffers, in veronal and borate buffers, and in adjusted solutions of saline and distilled water was investigated. The results demonstrate that the stability of this virus can vary considerably at pH 7 depending upon the nature and concentration of the salts present. Borate, veronal, and ...
A method for preparing highly purified glutaminase (EC 3.5.1.2, L-glutamine amidohydrolase) from pig renal cortex is described. The main steps consist of sodium sulfate fractionation followed by alternative solubilization by dialysis against Tris-HCI buffer and precipitation with phosphateborate. The linal enzyme preparation contains no impurities which could be detected by sucrose gradient cen...
Total boron concentrations in Drosophila changed during development and aging. The highest concentration of boron was found during the egg stage, followed by a decline during the larval stages. Newly emerged flies contained 35.5 ppm boron. During the adult stage the boron concentration increased by 52% by 9 weeks of age. Adding excess dietary boron during the adult stage decreased the median li...
Aldol addition reactions of dihydroxyacetone (DHA) to N-Cbz-amino aldehydes catalyzed by L-rhamnulose-1-phosphate aldolase (RhuA) in the presence of borate buffer are reported. High yields of aldol adduct (e.g. 70-90%) were achieved with excellent (>98 : 2 syn/anti) stereoselectivity for most S or R configured acceptors, which compares favorably to the reactions performed with DHAP. The stereoc...
Chemical and biological properties of the ice nucleating sites of Pseudomonas syringae, strain C-9, and Erwinia herbicola have been characterized. The ice nucleating activity (INA) for both bacteria was unchanged in buffers ranging from pH 5.0 to 9.2, suggesting that there were no essential groups for which a change in charge in this range was critical. The INA of both bacteria was also unaffec...
Our recent work has provided new insights into the equilibria and species that exist in aqueous solution at different pHs for the boric acid - hydrogen peroxide system, and the role of these species in oxidation reactions. Most recently, (M. C. Durrant, D. M. Davies and M. E. Deary, Org. Biomol. Chem., 2011, 9, 7249-7254), we have produced strong theoretical and experimental evidence for the ex...
The RNA World is generally thought to have been an important link between purely prebiotic (>3.7 Ga) chemistry and modern DNA/protein biochemistry. One concern about the RNAWorld hypothesis is the geochemical stability of ribose, the sugar moiety of RNA. Prebiotic stabilization of ribose by solutions associated with borate minerals, notably colemanite, ulexite, and kernite, has been proposed as...
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