Effect of aluminum co-doping on the formation of Yb2+ in Ytterbium-doped high silica glass

Yb3+ singly doped and Yb3+/Al3+ co-doped high silica glass samples are prepared,and their luminescent properties are investigated.Al3+ is considered as a beneficial activator for Yb3+-doped glass.However,the experimental result shows that the addition of Al3+ results in the transformation from Yb3+ to Yb2+ and the improvement in the photon luminescence of Yb2+.These characteristics indicate the role of Al3+ in Yb3+-doped glass.     

A new cyclic peptide from the marine fungal strain <Emphasis Type="Italic">Aspergillus</Emphasis> sp<Emphasis Type="Italic">.</Emphasis> AF119

A new cyclic heptapeptide containing γ-aminobutyric acid in the ring, namely unguisin E (1), was isolated from the fermentation culture of Aspergillus sp. AF119. The structure was elucidated by spectroscopic analyses, including 1D and 2D NMR experiments, and HR ESI-Q-TOF mass spectrometry, and by comparison with those reported. Compound 1 was evaluated for its antimicrobial activities by the paper diffusion method.     

Synthesis and characterization of well‐defined lactic acid–PEG cooligomers and its tricarbonyl rhenium conjugates

This article describes the synthesis and characterization of hydroxyl tailored, molecularly defined biodegradable cooligomers capable of chelating rhenium for potential radiopharmaceuticals. New insights were gained during the synthesis of lactide based on dimethylaminopyridine‐catalyzed transesterification. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Low band gap copolymers consisting of porphyrins,thiophenes, and 2,1,3‐benzothiadiazole moieties for bulk heterojunction solar cells

Two novel low band gap conjugated copolymers containing porphyrins, thiophenes, and 2,1,3‐benzothiadiazole ( BTZ ) moieties were synthesized and applied in bulk heterojunction solar cells. The thermal, optical, electrochemical, and photovoltaic properties of the two copolymers were examined to investigate the effect of the introduction of BTZ moiety in the backbone of the porphyrin polymers. The copolymers exhibited good thermal stability and film‐forming ability. The absorption spectra indicated that the BTZ moiety has significant influence on the UV–visible region spectra of the copolymers: with increasing the molar amount of BTZ moieties in conjugated main chain, the absorption in the range of 450–700 nm is largely broadened and red‐shifted compared to the similar polymers without BTZ moiety, and the optical band gaps of copolymers were narrowed to ～1.50 eV. The photoluminescence spectra showed that there is effective charge transfer in the whole conjugated main chain. Cyclic voltammetry displayed that the band gaps were reduced effectively by the introduction of the BTZ moieties. The bulk heterojunction solar cells were fabricated based on the blend of the copolymers and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) in a 1:2 weight ratio. The maximum power conversion efficiency of 0.91% was obtained by using P2 as the electron donor under the illumination of AM 1.5, 100 mW/cm². © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

套管外压挤毁强度分析与计算

在对大量的套管全尺寸挤毁试验结果分析的基础上，提出套管外压失稳机理：实际工程中的套管截面不是理想圆，在外压作用下的非圆套管圆周方向上环向应力分布不均匀，有附加弯矩效应；随外压增加，在最大压缩环向应力处达到屈服；当屈服逸到一定程度时，材料由于强度承载力不足而失效，导致套管发生失稳挤毁。基于上述套管强度挤毁准则，分析了理想弹塑性套管在轴向载荷作用下的抗挤强度计算方法，得到较保守的套管挤毁压力计算公式。与试验结果对比表明：导出的计算公式偏差较小，计算精度满足工程要求，失稳强度准则是适用的。     

聚乙烯吡咯啉酮对稀土变色酸双偶氮类试剂显色反应的褪色作用

研究了非离子型表面活性剂聚乙烯吡咯啉酮（ＰＶＰ）、（ＮＨ４）２ＳＯ４对ＲＥ（Ⅲ）、Ｆｅ（Ⅲ）、Ｚｒ（Ⅳ）、Ｔｈ（Ⅳ）、Ｃｕ（Ⅱ）等离子与变色酸双偶氮类试剂显色反应的影响。建立了大量稀土存在下测定微量Ｆｅ（Ⅲ）的新方法。纯稀土中Ｆｅ（Ⅲ）的测定，回收率在９８．０％～１０１．０％；对矿样测定，６次测定ＲＳＤ为１．７９％。