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641.
Thirlway J Lewis R Nunns L Al Nakeeb M Styles M Struck AW Smith CP Micklefield J 《Angewandte Chemie (International ed. in English)》2012,51(29):7181-7184
Calcium-dependent antibiotics (CDA) are cyclic lipopeptides assembled by nonribosomal peptide synthetase (NRPS) enzymes. Active site modification of the 3-methyl glutamate activating adenylation (A) domain of the CDA NRPS enables the incorporation of synthetic 3-methyl glutamine into CDA. This provides the first example of how A-domains can be engineered to introduce synthetic "non-natural" amino acids into nonribosomal peptides. 相似文献
642.
Jenny Yue Zuo Kai Knoerzer Raymond Mawson Sandra Kentish Muthupandian Ashokkumar 《Ultrasonics sonochemistry》2009,16(4):462-468
The effect of sonication on the pasting properties of waxy rice starch solutions (5 wt%) was investigated. It has been found that the functionality of starch granules was significantly influenced by the length of sonication and the solution temperature. A comparison of the pasting behaviour showed that the peak and final viscosities of the starch dispersions sonicated at temperatures near the onset temperature of gelatinisation were lower than those of the non-sonicated dispersions. The particle size measurements showed that the size of the heated and sonicated granules were smaller than that of the heated non-sonicated starch granules. Scanning electron microscopy (SEM) observations showed that the starch granule surface was not affected by sonication, and the size exclusion chromatography did not show any reduction in the size of the starch molecules. Based on these observations, the change in the pasting behaviour is explained in terms of the solubilisation of the swollen starch granules and starch aggregates induced by sonication. 相似文献
643.
Jenny Cooley 《Archiv der Mathematik》2013,100(5):401-411
Let S be a smooth cubic surface defined over a field K. As observed by Segre [5] and Manin [3, 4], there is a secant and tangent process on S that generates new K-rational points from old ones. It is natural to ask for the size of a minimal generating set for S(K). In a recent paper, for fields K with at least 13 elements, Siksek [7] showed that if S contains a skew pair of K-lines, then S(K) can be generated from one point. In this paper we prove the corresponding version of this result for fields K having at least 4 elements, and slightly milder results for # K = 2 or 3. 相似文献
644.
We prove existence and almost everywhere regularity of an area minimizing soap film with a bound on energy spanning a given
Jordan curve in Euclidean space R
3.The energy of a film is defined to be the sum of its surface area and the length of its singular branched set. The class of
surfaces over which area is minimized includes images of disks, integral currents, nonorientable surfaces and soap films as
observed by Plateau with a bound on energy. Our area minimizing solution is shown to be a smooth surface away from its branched
set which is a union of Lipschitz Jordan curves of finite total length. 相似文献
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