Stereospecific radical polymerization of optically active (S)-N-(2-hydroxy-1-phenylethyl) methacrylamide catalyzed by Lewis acids

The effects of Lewis acids, namely, rare earth metal trifluoromethanesulfonates, on the radical polymerization of (S)-N-(2-hydroxy-1-phenylethyl) methacrylamide were examined under various conditions. In the absence of Lewis acids, syndiotactic-rich polymers (r = 84%) were obtained, whereas in the presence of a catalytic amount of Lewis acids, the polymerization proceeded in an isotactic-specific manner (m up to 64%). Polymerization solvents strongly influenced the effect of the Lewis acids. The polymerization in n-butyl alcohol showed the highest isotactic selectivity, whereas the polymerization in DMSO showed no isotacticity-enhancing effect. Further increases in the Lewis acid concentration and the polymerization temperature did not produce clear effects on the tacticity of the polymers. The interaction between the monomer and Lewis acids was investigated, and the plausible mechanism of stereocontrol in the radical polymerization of (S)-HPEMA was analyzed based on the Lewis acid-monomer interaction.     

Plutonium-239 sorption and transport on/in unsaturated sediments: comparison of batch and column experiments for determining sorption coefficients

Sorption (distribution) coefficients of plutonium were most often derived by static batch experiments. However, it is not clear how unsaturated flow conditions including moisture content and pore water velocity change the sorption coefficients. Transport experiments of plutonium through the unsaturated sediments packed into the columns were then performed in order to determine the sorption coefficients (column-K _ds). Static batch experiments were also conducted to obtain batch-K _ds and then compare the differences between batch-K _ds and column-K _ds. The results show that unsaturated flow conditions had no significant effect on column-K _ds, and the average column-K _d value was 1.74 ± 0.02 m³/kg. By comparison, batch-K _d values spanned several orders of magnitude, regardless of the specified liquid–solid conditions. Moreover, the batch-K _d (22.7 m³/kg) at the standard L/S (4 mL/g) recommended by ASTM D 4319 was over an order of magnitude larger than the average column-K _d.     

The Effect of Albumin Fusion Patterns on the Production and Bioactivity of the Somatostatin-14 Fusion Protein in Pichia pastoris

Somatostatin is a natural inhibitor of growth hormone, and its analogues are clinically used for the therapy of acromegaly, gigantism, thyrotropinoma, and other carcinoid syndrome. However, natural somatostatin is limited for clinical usage because of its short half-life in vivo. Albumin fusion technology was used to construct long-acting fusion proteins, and Pichia pastoris was used as an expression system. Three fusion proteins, (somatostatin (SS)14)₂-human serum albumin (HSA), (SS14)₃-HSA, and HSA-(SS14)₃, were constructed with different fusion copies of somatostatin-14 and fusion orientations. The expression level of (SS14)₃-HSA and HSA-(SS14)₃ was much lower than (SS14)₂-HSA due to the additional fusion of the somatostatin-14 molecule. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry revealed that severe degradation occurred in the fermentation process. Similar to the standard of somatostatin-14, all three fusion proteins were able to inhibit growth hormone secretion in the blood, with (SS14)₂-HSA being the most effective one. On the whole, (SS14)₂-HSA was the most effective protein in both production level and bioactivity, and increasing the number of small protein copies fused to HSA may not be a suitable method to improve the protein bioactivity.     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

Highly Stereoselective Conjugate Addition and α‐Alkynylation Reaction with Electron‐Deficient Alkynes Catalyzed by Chiral Scandium(III) Complexes

The highly Z‐selective asymmetric conjugate addition of 3‐substituted oxindoles to alkynyl carbonyl compounds has been developed by using scandium complexes of chiral N,N′‐dioxides under mild conditions. The thermodynamically unstable Z‐olefin derivatives were obtained in excellent yields and high enantiomeric and geometric control. The catalyst was also found to be effective in the asymmetric acetylenic substitution reaction of 3‐substituted oxindoles, giving excellent enantioselectivities.     

化学浴沉积方法制备硫化铟敏化太阳电池及其性能研究

硫化铟是一种稳定、低毒性的半导体材料. 本文采用低成本的化学浴沉积方法制备了硫化铟敏化太阳电池, X射线衍射(XRD)、光电子能谱(XPS)和扫描电镜(SEM)结果表明形成了硫化铟敏化的二氧化钛薄膜. 化学浴沉积温度对所得硫化铟敏化薄膜的形貌有显著的影响, 进而影响电池性能. 温度太低时, 化学浴沉积反应速率太低, 只发生少量沉积; 温度太高时, 化学浴沉积反应速率较快, 硫化铟来不及沉积到二氧化钛多孔薄膜内部. 当温度在40℃时, 硫化铟沉积均匀性最好, 薄膜的光吸收性能最佳, 电池的短路电流最大, 另外, 填充因子达到最佳, 为65%, 电池总体光电转换效率为0.32%.     

SiO2/TiO2-xCx/C的制备、表征及其吸附和可见光催化性能

以SiO2为成核中心,钛酸四丁酯为钛源,分别以多羟基化合物乙二醇、丙三醇、葡萄糖和聚乙烯醇为联接剂,采用水解沉淀法制备了碳掺杂和包覆的多孔SiO2/TiO2-xCx/C可见光响应型光催化剂。采用X-射线衍射(XRD)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)、傅里叶变换-红外光谱(FTIR)、比表面积(BET)和紫外-可见(UV-Vis)漫反射光谱对样品进行表征。对不同结构样品的形成机理进行了分析。以次甲基蓝(MB)溶液为模拟废水,对样品的吸附性能和可见光催化性能进行了评价。结果表明,多羟基化合物对材料的结构和性能有重要影响。碳的掺杂和包覆使材料的吸收光谱包含了整个可见光区,而多孔结构使材料的吸附性能得到提高。以聚乙烯醇为原料所得样品吸附性能最好,30 min内吸附率达到70%;而以丙三醇为原料所得样品具有最好的可见光催化性能,40 min内次甲基蓝的降解率达到95%。     

生物基化工与材料产业技术的开发与探索

本文阐述了中国石油化工集团公司(中国石化)在生物基化工与材料领域的探索路径和发展战略,介绍了中国石化近年来在生物基单体、生物基材料与可降解材料等领域开展的创新实践及取得的阶段性成果,主要包括乳酸—聚乳酸、丁二酸/二元醇—生物可降解材料、长链二元酸—生物基尼龙以及生物质芳烃—聚对苯二甲酸乙二酯(PET)等技术领域.提出了建立生物基化工与材料科学技术平台、突破关键技术、发展新兴产业等建议.