Direct transition metal-free C-S bond formation: synthesis of 2-aminobenzothiazole derivatives via base-mediated approach

A general, efficient, and more practical protocol for the base-mediated intermolecular or intramolecular S-arylation leading to the 2-aminobenzothiazole derivatives is reported. Remarkably, all reactions were carried out under transition-metal-free conditions with good to excellent yields, rendering the methodology presented herein highly valuable from both environmental and economic points of view.     

Copper‐catalyzed Clauson–Kass pyrroles synthesis in aqueous media

An efficient and convenient copper‐catalyzed Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with amines in aqueous media has been developed, providing a wide range of N‐substituted pyrroles in good yields. It is noteworthy that the Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with p‐phenylenediamine or m‐phenylenediamine proceeds smoothly to afford the corresponding monopyrroles and bispyrroles with high selectivity in impressive yields. A plausible mechanism for the formation of N‐substituted pyrroles has been proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Discontinuous crack-bridging model for fracture toughness analysis of nacre

Studying the structure–property relation of biological materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of advanced biomimetic materials. In this paper, we present a microstructure-based fracture mechanics model to investigate the toughening effect due to the crack-bridging mechanism of platelets. Our theoretical analysis demonstrates the crucial contribution of this mechanism to the high toughness of nacre. It is found that the fracture toughness of nacre exhibits distinct dependence on the sizes of platelets, and the optimized ranges for the thickness and length of platelets required to achieve higher fracture toughness are given. In addition, the effects of such factors as the mechanical properties of the organic phase (or interfaces), the effective elastic modulus of nacre, and the stacking pattern of platelets are also examined. Finally, some guidelines for the biomimetic design of novel materials are proposed based on our theoretical analysis.     

Experimental study of enhanced emission of the laser-ablated plume in backing gas

The effects of background gases on the optical emission of the excimer-laser-ablated plume from a brass target have been studied experimentally. It is found that the plume emission can be enhanced significantly in a proper gas ambient. In hydrogen, the highest peak intensity is detected, and in argon, there is a distinctive difference in the pressure-dependent emission between in He and in the other three gases, Ar, N₂ and H₂. Moreover, the monitored line peak intensity remains unchanged in Ar and N₂ and increases in H₂ within a distance above the target surface; but in He, the observed peak intensity decreases with distance like in vacuum. Furthermore, the emissions of several more atomic lines of Cu and Zn atoms from the plume are also found to be enhanced in the same manner in gas ambient. Some physical processes involved in the plume expansion and the possible mechanisms for the enhanced emission of the plume in backing gas are discussed.     

3-甲酰腙一利福霉素SV及其异构体的研究

用发酵和化学法合成的两个3-甲酰腙-利福霉素SV样品(1^#,2^#)具有不同的物理化学性质,本文用多种NMR技术,如¹H,¹³C,DEPT,¹H-¹H COSY,反相摸式的¹H-¹³C COSY及远程¹H-¹³C COSY,并结合红外及紫外一可见光谱测试结果进行综合分析,确定样1^#及样2^#分别为酰胺式主产品及亚胺醇式导构体。根据实验结果对样1^#的异构化反应进行了初步的探讨.     

Size dependence of a magnetopolaron in cylindrical quantum wires at arbitrary magnetic fields

With the use of variational method to solve the effective mass equation, we have studied the cyclotron resonance of a magnetopolaron in cylindrical quantum wires at arbitrary magnetic fields. The interaction of the electron with surface-optical (SO) phonons is used. Having calculated the ground state energy and the excited state energy of the magnetopolaron, we obtain the hybrid frequency of the magnetopolaron in quantum wires.     

毛细管区带电泳分析阿片受体和抗独特型抗羟甲芬太尼抗体

应用毛细管区带电泳（ＣＺＥ）分析测定阿片受体、抗独特型抗羟甲芬太尼抗体等生物大分子样品。熔融石英毛细管柱为６０ｃｍ×１００μｍｉ．ｄ．（从进样到检测器长度为５０ｃｍ）,以硼砂－氢氧化钾为缓冲液。结果表明缓冲液的ｐＨ影响ＣＺＥ对阿片受体的分析,当ｐＨ为９．０时分析效果最理想,重现性良好,测得的两个主峰与同批样品进行ＳＤＳ－ＰＡＧＥ分析得到的两个条带相符。用ＣＺＥ分析抗独特型抗羟甲芬太尼抗体（ＩｇＧ）,表明用ＰｒＯｔｅｉｎＡ－Ｓｅｐｈａｒｏｓｅ亲和色谱分离得到部分纯化的ＩｇＧ,迁移时间不同于对照豚鼠的ＩｇＧ。