On the Involutive Solutions of Solition Hierarchy

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Purity determination of yunaconitine reference standard using HPLC with experimental design and response surface optimization

Experimental design and response surface methodology have been used for the development of the stability‐indicating HPLC method for the purity determination of yunaconitine reference standard. Significant factors including the contents of ACN, perchloric acid, triethylamine (TEA), and column temperature were optimized using a Box–Behnken design. A mixture of crude yunaconitine extract and degradation solutions of yunaconitine under stress conditions was chromatogramed. The normalized peak area of total impurities, the retention time of yunaconitine, and the resolutions between yunaconitine and its adjacent peaks were selected as optimization criteria. Derringer desirability function of the multicriteria and the tested factors were used to establish 3‐D response surfaces. The optimal condition was achieved with a mobile phase of ACN/water (30:70, containing 0.125% perchloric acid and 1.0% TEA) at a column temperature of 37.5°C. The method was validated and shown comparable to that of phase solubility analysis. As a result, the newly developed method can be used to determine the chromatographic purity and stability of the yunaconitine reference standard.     

Phase Equilibrium CsBr-CeBr3-HBr(12.52 wt %)—H2O at 298 ± 0.1 K and a New Solid Phase Compound

The equilibrium solubility of the quaternary system CsBr-CeBr₃-HBr(12.52 wt %)-H₂O was determined at 298K and the corresponding equilibrium diagram was constructed. The quaternary system is complicated by three equilibrium solid phases: CsBr, Cs₅Ce₂Br₁₁ · 22H₂O (5: 2 type), and CeBr₃ · 7H₂O, of which the new compound Cs₅Ce₂Br₁₁ · 22H₂O was found to be incongruently soluble in the system. The new compound obtained was identified and characterized by the method of X-ray diffraction and the thermal analysis methods of thermogravimetry-differential thermogravimetry (TG-DTG), and it loses its crystal water in two steps from 325 to 511 K. The standard molar enthalpy of solution of Cs₅Ce₂Br₁₁ · 22H₂O in deionized water was measured to be (129.105 ± 0.150) kJ mol⁻¹ with a heat conduction microcalorimeter. The standard molar enthalpy of formation was calculated as (−10438.215 ± 0.150) kJ mol⁻¹. This article was submitted by the authors in English.     

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.