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The routine use of the INEPT pulse sequence is shown to be the method of choice for the assignment of multiplicity from 13C NMR spectra where no prior information about the 1J(CH) coupling constants is available, or where these are expected to vary over a large range. This technique is illustrated using spectra obtained from polyhalogenated monoterpenes isolated from the red alga Plocamium angustum, which have 1J(CH) values varying from 127 to 203 Hz. 相似文献
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Petriellin A is a novel cyclic depsipeptide antifungal compound consisting of nine l-configured residues, one d-phenyllactic acid (PhLac) and three unknown chiral centres: two N-methyl-threonines (MeThr1 & MeThr2) and one N-methyl-isoleucine (MeIle). NMR experiments including 2D ROESY, NOESY along with structural and energy calculations predicted that the unknown chiral centres were all l-configured, which was later verified chemically. Simulated annealing, dynamics calculations and minimisation processes showed Petriellin A to have a folded "C-shaped" structure. 相似文献
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Brownlee Alexander E. I. Epitropakis Michael G. Mulder Jeroen Paelinck Marc Burke Edmund K. 《Journal of Heuristics》2022,28(4):509-538
Journal of Heuristics - Industrial software often has many parameters that critically impact performance. Frequently, these are left in a sub-optimal configuration for a given application because... 相似文献
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The Navier–Stokes equations arise naturally as a result of Ehrenfests’ coarse-graining in phase space after a period of free-flight
dynamics. This point of view allows for a very flexible approach to the simulation of fluid flow for high-Reynolds number.
We construct regularisers for lattice Boltzmann computational models. These regularisers are based on Ehrenfests’ coarse-graining
idea and could be applied to schemes with either entropic or non-entropic quasiequilibria. We give a numerical scheme which
gives good results for the standard test cases of the shock tube and the flow past a square cylinder. 相似文献
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Aurelio L Box JS Brownlee RT Hughes AB Sleebs MM 《The Journal of organic chemistry》2003,68(7):2652-2667
N-Methyl amino acids occur in many natural products. Experimental strategies are presented for a unified approach to the synthesis of N-methyl derivatives through 5-oxazolidinones of the 20 common l-amino acids. The amino acids with reactive side chains that required protecting groups or devoted syntheses for side chain construction for N-methylation to proceed included serine, threonine, tyrosine, cysteine, methionine, tryptophan, asparagine, histidine, and arginine. The studies have provided improved methods for the preparation of N-methyl serine, threonine, and tyrosine. All 20 of the common l-amino acids are now available in suitable forms for solid or solution-phase peptide synthesis. 相似文献
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R. A. Brownlee 《Numerical Algorithms》2005,39(1-3):57-68
The error between appropriately smooth functions and their radial basis function interpolants, as the interpolation points fill out a bounded domain in Rd, is a well studied artifact. In all of these cases, the analysis takes place in a natural function space dictated by the choice of radial basis function – the native space. The native space contains functions possessing a certain amount of smoothness. This paper establishes error estimates when the function being interpolated is conspicuously rough.
AMS subject classification 41A05, 41A25, 41A30, 41A63R.A. Brownlee: Supported by a studentship from the Engineering and Physical Sciences Research Council. 相似文献
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R. T. C. Brownlee A. F. Masters M. J. O'Connor A. G. Wedd H. A. Kimlin J. D. Cotton 《Magnetic resonance in chemistry : MRC》1982,20(2):73-77
A systematic study has been made of the effects of substituent induced chemical shifts in [(η5-C5H5)(CO)3Mo(CH2C6H4R)] compounds. Both 95Mo and 13C NMR shifts in the aromatic ring are reported. The (η5-C5H5)(CO)3MoCH2? group is a reasonably strong resonance donor (σR° = ?0.21) and weak inductive donor (σI = ?0.07). The molybdenum chemical shifts are extremely sensitive to the effects of distant substituents (range c. 40 ppm). Since the shift correlates well with substituent constants in this series, it is suggested that the chemical shift is controlled by the paramagnetic term for this spin 5/2 nucleus. 相似文献
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[2S,3S-Hmp]-Aureobasidin L 2 has been successfully synthesised through a combination of solution- and solid-phase peptide synthesis. All of the Fmoc-protected residues including a depsidipeptide, Fmoc-MeVal-Hmp-OH, were prepared in solution phase. Chain elongation on chlorotrityl resin was undertaken using selected coupling reagents including HBTU/HOBt, HATU/HOAt and BTC/collidine. Cleavage of the linear depsinonapeptide was followed by cyclisation to give the desired cyclodepsipeptide. 相似文献