Conformationally constrained analogues of diacylglycerol. 24. Asymmetric synthesis of a chiral (R)-DAG-lactone template as a versatile precursor for highly functionalized DAG-lactones

[structure: see text] Commercially available 2-methylenepropane-1,3-diol was converted to chiral epoxide (R)-2 via Sharpless asymmetric epoxidation in >96% ee. Regiospecific epoxide ring opening and reduction of the intermediate alkyne set the stage for a one-pot lactonization to give (R)-6, a convenient precursor for all functionalized chiral DAG-lactones used as potent PK-C ligands. The synthesis of the most potent DAG-lactones known to date, (Z)-10 and (E)-10, served to confirm PK-C's exclusive preference for the (R)-stereochemistry in this class of compounds.     

Diffraction of a superfluid fermi gas by an atomic grating

An atomic grating generated by a pulsed standing-wave laser field is proposed to manipulate the superfluid state in a quantum degenerate gas of fermionic atoms. We show that in the presence of atomic Cooper pairs, the density oscillations of the gas caused by the atomic grating exhibit a much longer coherence time than that in the normal Fermi gas. Our result indicates that the technique of a pulsed atomic grating is a potential candidate to detect the atomic superfluid state in a quantum degenerate Fermi gas.     

A Study of the Measurement of Surface and Interfacial Tension by the Maximum Liquid Drop Volume Method

The maximum liquid drop volume (v(max)) is measured by using a back-suction micrometer syringe piston technique. Different very viscous liquids are measured by (v(max)) and (v(f)) methods to observe the effect of viscosity on tension measurement. No apparent viscosity effect was observed in surface tension data obtained by using Harkins-Brown factors and the theoretical correction factors in the viscosity range 5.9-100,900 mP. Copyright 2001 Academic Press.     

Boundary element method for moving and rolling contact of 2D elastic bodies with defects

A scheme of boundary element method for moving contact of two-dimensional elastic bodies using conforming discretization is presented. Both the displacement and the traction boundary conditions are satisfied on the contacting region in the sense of discretization. An algorithm to deal with the moving of the contact boundary on a larger possible contact region is presented. The algorithm is generalized to rolling contact problem as well. Some numerical examples of moving and rolling contact of 2D elastic bodies with or without friction, including the bodies with a hole-type defect, are given to show the effectiveness and the accuracy of the presented schemes. The project supported by the National Natural Science Foundation of China (19772025)     

锂离子电池LiBOB电解质盐研究进展

本文介绍了可用于锂离子电池的新型锂盐--双乙二酸硼酸锂（LiBOB）的基本性质,包括结构组成、合成方法、物理化学性能及其与结构的关系。综述了近年来在LiBOB新型电解质锂盐研究与探索方面的新成果,重点评价了BOB-阴离子对于石墨负极和金属氧化物正极材料表面的电化学性能。讨论了这种盐在锂离子系中杂质和安全性等问题,归纳了其优缺点,指出今后电解质锂盐的研究发展方向。     

GLOBALLY CONVERGENT INEXACT GENERALIZED NEWTON METHODS WITH DECREASING NORM OF THE GRADIENT

AbstractIn this paper, motivated by the Martinez and Qi methods[l], we propose one type of globally convergent inexact generalized Newton methods to solve unconstrained optimization problems in which the objective functions are not twice differentiable, but have LC gradient. They make the norm of the gradient decreasing. These methods are implementable and globally convergent. We prove that the algorithms have superlinear convergence rates under some mile conditions.The methods may also be used to solve nonsmooth equations.     

A wideband tunable phase shifter based on orthogonal optical single-sideband

We present a novel technique to generate an orthogonally polarized optical single sideband （OSSB） generated by a tunable bandpass filter （TBF）. When the OSSB passes through the other polarization modulation （PolM） which is polarization dependent, the phase shift of the optical carrier and first-order sideband is different under different bias. As a result, a wideband tunable phase shifter is realized by adjusting the bias applied to the polarization modulator.     

Relation between soil matrix potential changes and water conversion ratios during methane hydrate formation processes in loess

With a new apparatus designed and assembled by ourselves, the matrix potential of non-saturated loess was firstly measured and studied during methane hydrate formation processes. The experimental results showed that during two formation processes, the matrix potential changes of the loess all presented a good linear relationship with water conversion ratios. In addition, although it was well known that the secondary gas hydrate formation was easier than the initial, our experimental results showed that the initial hydrate formation efficiency in non-saturated loess was higher than that of the secondary.     

A new isobenzofuranone derivative from a marine Streptomyces sp.

One new isobenzofuranone derivative,1,4-dimethoxy-3-(3R*-hydroxy-3R*-methyl-1-tetralone)-1(3H)-isobenzofuran(1),was isolated from the broth of marine Streptomyces sp.M268.The structure was elucidated by spectroscopy characteristics as well as comparison with the literature.Compound 1 exhibited cytotoxicities against human cancer cell,HL-60,A549,and BEL-7402.