Covalent functionalization of multi-walled carbon nanotubes by lipase

Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor.     

A Nonconforming Arbitrary Quadrilateral Finite Element Method for Approximating Maxwell's Equations

The main aim of this paper is to provide convergence analysis of Quasi-Wilson nonconforming finite element to Maxwell's equations under arbitrary quadrilateral meshes.The error estimates are derived,which are the same as those for conforming elements under conventional regular meshes.     

Crystallization process of Bi(Pb)-Sr-Ca-Cu-O glass

A crystallization study has been carried out for rapidly solidified Bi₂Pb_0.5Sr₂Ca₄Cu₅O_x glass. Glass transition temperature T _g, crystallized superconducting phases and microstructural changes were measured and analysed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The crystallization mechanism of the three superconducting phases — (2201) 20 K phase, (2212) 80 K phase, and (2223) 110 K phase — has been discussed, and a time-temperature-transformation diagram for the glass has been constructed.     

星载光学系统遮光罩消杂光结构优化设计方法

本文对星载光学系统遮光罩消杂光结构的优化设计做了初步探讨。提出了遮光罩和挡光环消杂光设计的基本原则。给出了一种二级遮光罩结构寸的优化设计方法和一种遮光罩内壁上挡光环位置优化设计方法,并对一级和二级遮光罩进行了初步的分析比较。     

Study on reproductive endocrinology of human placenta (III)--Hormonal regulation of progesterone production by trophoblast tissue of first trimester.

The effect of hormones on progesterone secretion by 6-8 week human trophoblast tissue cultured in serum-free medium has been investigated. GnRH at low concentration (10(-10)-10(-8) mol/L) stimulated progesterone secretion, while high dose (10(-6)-10(-5) mol/L) produced inhibitory effect. The progesterone secretion could be significantly decreased by addition of anti-hCG antiserum or monoclonal anti-hCG IgG in a dose- and time-dependent manner. Various concentrations of TRH, PGE2, PGF2 alpha, testosterone and estradiol were found to be ineffective. These data indicate clearly that progesterone production by human trophoblast tissue at early gestation stage is under the modulation of GnRH and hCG.     

Dielectronic Recombination of Very Heavy Lithiumlike Ions

Hyperfine Interactions - An overview of measurements of dielectronic recombination (DR) with the heaviest lithiumlike ions is presented. The experiments have been carried out at the heavy ion...     

工件带到达时间的两阶段柔性流水作业的近似算法

研究了工件带到时间的两阶段柔性流水作业的排序问题,基于求解流水作业和平行机问题的算法思想,提出两个相应的近似算法H(R)和H(MR(?)),证明了这两个算法的最坏情况性能比分别为3-1/m和2/5-1/m,讨论了界的紧性,并利用数值模拟以分析算法与最优值的近似性能比.     

Solvothermal Synthesis of Molybdenum Disulfide Hollow Spheres Modified by Cyanex 301 in Water–Ethanol Medium

Hollow spherical molybdenum disulfide has been successfully synthesized via a solvothermal method using Cyanex 301 as sulfur source and modification agent. The hollow spheres are characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Energy-Dispersive X-ray analysis. The influences of reaction conditions are also discussed while a mechanism is proposed to explain the formation of the peculiar morphology.     

复制缺陷型人泡沫病毒载体辅助质粒pΔGP的构建及转染小肠癌细胞的研究

在人泡沫病毒原病毒全长克隆pHRSV13的基础上,缺失突变gag和pol基因,并且用SV40polyA加尾信号替代人泡沫病毒的3′LTR,构建辅助质粒pΔGP.将复制缺陷型人泡沫病毒载体质粒pGPSNI EGFP和辅助质粒pΔGP分别转染和共转染小肠癌HIC细胞系,荧光显微镜检测发现共转染pGPSNI EGFP和pΔGP的HIC细胞能够强烈表达绿色荧光蛋白,转染有复制缺陷型人泡沫病毒载体质粒pGPSNI EGFP的HIC细胞能够表达少量的绿色荧光蛋白,而转染有辅助载体pΔGP的HIC细胞不表达绿色荧光.结果证明复制缺陷型人泡沫病毒载体的构建成功,表明人泡沫病毒env基因3′端的内部启动子IP具有弱启动子的活性,并且bel基因产生的调控蛋白能够反式激活人泡沫病毒内部启动子IP和5′LTR的启动子.     

2‐Cyanoprop‐2‐yl dithiobenzoate mediated reversible addition–fragmentation chain transfer polymerization of acrylonitrile targeting a polymer with a higher molecular weight

The reversible addition–fragmentation chain transfer (RAFT) polymerization of acrylonitrile (AN) mediated by 2‐cyanoprop‐2‐yl dithiobenzoate was first applied to synthesize polyacrylonitrile (PAN) with a high molecular weight up to 32,800 and a polydispersity index as low as 1.29. The key to success was ascribed to the optimization of the experimental conditions to increase the fragmentation reaction efficiency of the intermediate radical. In accordance with the atom transfer radical polymerization of AN, ethylene carbonate was also a better solvent candidate for providing higher controlled/living RAFT polymerization behaviors than dimethylformamide and dimethyl sulfoxide. The various experimental parameters, including the temperature, the molar ratio of dithiobenzoate to the initiator, the molar ratio of the monomer to dithiobenzoate, the monomer concentration, and the addition of the comonomer, were varied to improve the control of the molecular weight and polydispersity index. The molecular weights of PANs were validated by gel permeation chromatography along with a universal calibration procedure and intrinsic viscosity measurements. ¹H NMR analysis confirmed the high chain‐end functionality of the resultant polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1272–1281, 2007