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H. H. Sutherland Z. Ali Adib G. W. Gray D. Lacey G. Nestor K. J. Toyne 《Liquid crystals》2013,40(10):1293-1300
Abstract A series of terminally cyano substituted side chain polysiloxanes have been characterized using optical microscopy, D.S.C., and X-ray diffraction. Values for the lamellar spacings, d, of the interdigitated smectic A phases were obtained, and the variations in d with temperature and length of the flexible aliphatic spacer are discussed. The spacing for m = 4, 5, and 6 increased regularly with m whereas the short m = 3 spacer gave an anomalously high value. 相似文献
94.
Stepan Shipovskov Karsten M. Kragh Brian S. Laursen Charlotte H. Poulsen Flemming Besenbacher Duncan S. Sutherland 《Applied biochemistry and biotechnology》2010,160(4):1124-1129
The formation of noncovalent complexes between glycosidase, endo-1,4-β-d-mannanase, and ionic surfactant di(2-ethylhexyl) sodium sulfosuccinate (AOT) was shown to promote protein transfer into organic
solvents such as xylene and hexane. It was found that mannanase can be solubilized in hexane and in xylene with concentration
at least 2.5 and 2.0 mg/ml, respectively. The catalytic activity of the enzyme in hexane spontaneously increases with the
concentration of AOT and is about 10% of the activity in aqueous system. In xylene, a catalytic activity higher than that
in bulk aqueous conditions was found for the samples containing 0.1–0.3 mg/ml of mannanase, while for the samples with a higher
concentration of enzyme, the activity was hardly detected. 相似文献
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For a prime l, let Φ l be the classical modular polynomial, and let h(Φ l ) denote its logarithmic height. By specializing a theorem of Cohen, we prove that \(h(\Phi_{l})\le 6l\log l+16l+14\sqrt{l}\log l\). As a corollary, we find that h(Φ l )≤6llog?l+18l also holds. A table of h(Φ l ) values is provided for l≤3600. 相似文献
98.
Xiaocheng Qi Svetlana Ignatova Guoan Luo Qionglin Liang Frank Wu Jun Yiming Wang Ian Sutherland 《Journal of chromatography. A》2010,1217(13):1995-2001
Ginseng is a popular herb worldwide and has had varied uses in traditional Asian medicine for thousands of years. There are several different species of the herb, but all share the same constituents. Ginsenosides, the most extensively studied chemical components of ginseng, are generally considered to be one of the most important active ingredients of the plant. In this study, we have developed fast and efficient methodology for isolation of four known ginsenosides Rf, Rd, Re and Rb1 from Ginseng by high performance counter-current chromatography (HPCCC) coupled with evaporative light scattering detection (ELSD). The crude sample for HPCCC was purified firstly from a ginseng extraction using macroporous resin. The enriched saponin fraction (480 mg) was separated by using methylene chloride–methanol–5 mM aqueous ammonium acetate–isopropanol (6:2:4:3, v/v,) as the two-phase solvent system and yielded 10.7 mg of Rf, 11.0 mg of Rd, 13.4 mg of Re and 13.9 mg of Rb1. The purity of these ginsenosides was 99.2%, 88.3%, 93.7% and 91.8%, respectively assessed by HPLC-DAD-ELSD, and their structures were characterized by electrospray ionization mass spectrometry (ESI-MS) and compared with standards. Ammonium acetate was used to shorten the separation time and eliminate emulsification together with a flow step-gradient. The salt can be removed by re-dissolving the sample using acetone. 相似文献
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The use of a non-coordinating solvent for the aza-Claisen rearrangement of delta,epsilon-disubstituted acetimidates switches on a substrate directing effect that gives excellent stereoselectivity. 相似文献
100.