A new free recoverable and reusable mono-alkaloid-type ligand and its use in preparation of ethyl （2R,3S）-2,3-dihydroxy-3-phenylpropionate

A new free recoverable and reusable mono-alkaloid-type ligand has been synthesized by a simple method.With highly polar groups,the ligand can be recycled and reused eight times to prepare ethyl(2R,3S)-2,3-dihydroxy-3-phenylpropionate with high yield and ee via asymmetric dihydroxylation(AD) reaction.     

Microwave-promoted solvent-free synthesis of N-(diphenylmethylene)glycine alkyl esters

The efficient synthesis of N-(diphenylmethylene) glycine alkyl esters was achieved for the first microwave irradiation under solvent-free condition,using PEG or quaternary ammonium salts as phase transfer catalysts(PTCs).Under the optimum conditions, N-(diphenylmethylene) glycine alkyl esters were obtained in excellent yields in most cases.     

Interaction of cleavage ridges with grain boundaries in polysilicon films

The morphology of cleavage surfaces across grain boundaries in free-standing silicon thin films was investigated. Three ridge–boundary interaction modes were identified. If the cleavage ridge was relatively deep, it could directly bypass a grain boundary. If it was relatively shallow, it would act as a stress concentrator promoting cleavage front transmission. It was also observed that due to the smoothening effect, the surface could become effectively less rough across a grain boundary. PACS 82.45.Mp; 85.30.De; 61.72.Mm; 60.20.Mk     

基于最小二乘迭代的多光束相移算法

高阶谐波和随机相移误差是影响干涉测量精度的主要因素.为了同时解决这两问题,提出了基于最小二乘迭代的多光束干涉条纹分析方法.该方法利用傅里叶级数将多光束干涉条纹展开为基波和各阶谐波之和.它只需要5帧随机相移的多光束干涉条纹,即可通过最小二乘迭代准确地求得相移值和相位分布.模拟计算结果表明,当测试面反射系数小于0.6、随机相移误差的均方根小于1时,只需10次迭代运算即可将误差控制在0.005 (PV)和0.003(RMS)rad之下,精度比传统的五步算法精度高.实验结果进一步验证了该算法的有效性,并表明该算法比双光束相移算法优越.     

Study of the oxidation dynamics of ethyl cysteinate dimer in solution by ultra‐performance liquid chromatography with tandem mass spectrometry

Diaminodithiol (N₂S₂)‐type compounds readily oxidize to produce disulfides. We found that some ligands failed to produce a prospective protonated molecular ion peak but gave a peak of [M–2+H]⁺, whereas others produced both [M+H]⁺ and [M–2+H]⁺ peaks in electrospray ionization mass spectra. In this study, an important N₂S₂ ligand, the ethyl cysteinate dimer (ECD), was investigated with high‐resolution accurate mass measurements and tandem mass spectrometric analysis. The elemental compositions of ECD and its oxidized product were analyzed. The oxidation of ECD was confirmed. An ultra‐performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method in multiple reaction monitoring mode was developed, and ECD and its oxidized product were quantitated in solution. The dynamic oxidation process of ECD in solution was studied in detail. The full time course of the decrease in ECD and the increase in its oxide was observed; the oxidation procedure followed first‐order kinetics, and the half‐life time of ECD was 51 min. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,structural characterization and electrochemical recognition of metal ions of two new ferrocenylhydrazone‐based receptors

Two new ferrocenylhydrazone‐based receptors FcL₁ and FcL₂ were prepared and the X‐ray crystal structure of FcL₁ was described. The electrochemical studies reveal that the receptor FcL₁ is responsive to Hg²⁺ and Cr³⁺, whereas, receptor FcL₂ only responsive to Hg²⁺. The maximum electrochemical shift of FcL₁ for Cr³⁺ is about 56 mV. Copyright © 2009 John Wiley & Sons, Ltd.     

On Julia sets concerning phase transitions

The sets of the points corresponding to the phase transitions of the Potts model on the diamond hierarchical lattice for antiferromagnetic coupling are studied. These sets are the Julia sets of a family of rational mappings. It is shown that they may be disconnected sets. Furthermore, the topological structures of these sets are described completely.     

阳极连接中的物理学

介绍阳极连接技术和阳极连接过程中的物理现象以及有关阳极连接的初步理论。     

瞬态电子碰撞激发类氖锗19.6nm X射线激光的理论研究

近来，许多实验室仅采用一个脉宽为几个ps的短脉冲就得到了强放大的软X射线激光.这表明瞬态是来得及电离的.为此，在类氖锗的瞬态电子碰撞激发19.6nm 波长X射线激光研究中，提出了采用低预脉冲产生低电离度的预等离子体，后续一个ps级短脉冲既电离又加热等离子体的驱动方式.并用系列程序进行了模拟.模拟结果表明，这种驱动方式也可以得到高增益. 关键词： X射线激光 等离子体 增益系数 瞬态电子碰撞激发     

高分子的溶度参数理论

采用统计物理学方法，在Flory-Huggins高分子溶液理论中引入Gibbs分布，从而合理描述了高分子内聚能的温度依赖性.将此理论应用于求解高分子的溶度参数.采用此方法得到的溶度参数比以往的理论更加接近实验结果.这表明所推导的聚合物溶液热力学理论是合理的，可以更精确地求解高分子的溶度参数. 关键词： 高分子 溶度参数 Gibbs分布