A novel cationic triblock copolymer as noncovalent coating for the separation of proteins by CE

A novel noncovalent adsorbed coating for CE has been prepared and explored. This coating was based on quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-poly(ethylene oxide)-block-poly(2-(dimethylamino)ethyl methacrylate) (QDED) triblock copolymer which was synthesized by atomic transfer radical polymerization (ATRP) in our laboratory. The polycationic polymer and the negatively charged fused-silica surface attracted each other through electrostatic interactions and hydrogen bonds. It was demonstrated that the coated capillaries provided an electroosmotic flow with reverse direction, and the magnitude of the electroosmotic flow can be modulated by varying the molecular mass of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) block and pH value of the buffer. The effects of the molecular mass of PDMAEMA block in QDED triblock copolymer and pH value of the buffer on the separation of basic proteins were investigated in detail. The triblock copolymer coatings showed higher separation efficiency, better migration time repeatability and would apply to wider range of pH than bare fused-silica capillary when used in separating proteins. Proteins from egg white were also separated through this QDED triblock copolymer-coated capillary. These results demonstrated that the QDED triblock copolymer coatings are suitable for analyzing biosamples.     

ART-induced biophysical and biochemical alterations of Jurkat cell membrane

Integrity of the cell membrane is a basic requirement for maintaining the biological characteristics of a cell. In this study, cell membrane as the target of drug action was investigated. CCK-8 assay suggested that Artesunate (ART) could significantly suppress the proliferation of Jurkat cells in a dose-dependent manner. Changes in the morphology and mechanics of Jurkat cells were studied by atomic force microscopy (AFM). These changes included decrease of Young's modulus (from 3.18±0.54 to 1.72±0.54kPa), increase in the fluctuation of surface components, increase in shrinkage, or even the appearance of pores. The Young's modulus change was according to the F-actin protein, not the Tubulin-β or integrin β1 protein. Meanwhile, the activities of plasma membrane Ca(2+)-Mg(2+)-ATPase and Na(+)-K(+)-ATPase were also repressed following ART exposure as well as membrane potential. Western blot was used to detect Caspase 3 and Cyclin D1 protein level. The Cyclin D1 was downregulated and Caspase 3 was activated. Hence, cellular membrane represented a plausible target for ART-induced injury.     

Crystallization,rheological, and mechanical properties of PLLA/PEG blend with multiwalled carbon nanotubes

Functionalized multiwalled carbon nanotubes (FMWCNTs) were introduced into poly(L‐lactide)/polyethylene glycol (PLLA/PEG) blend and the effects of FMWCNTs on crystallization behaviors, rheological, and mechanical properties of PLLA/PEG/FMWCNTs were investigated. The results show that FMWCNTs exhibit good distribution in the nanocomposites and absorb some PEG to agglomerate around them. The crystallization behavior of PLLA in the nanocomposites is greatly dependent on the content of FMWCNTs. At low content of FMWCNTs, the addition of FMWCNTs improves the crystallization behavior of PLLA by enhancing the crystallization temperature and accelerating the crystallization rate, whereas at high content of FMWCNTs, the crystallization of PLLA is restricted to a certain degree. Rheological properties show the formation of the network structure of FMWCNTs at high content, which is the main reason for the retarded crystallization behavior of PLLA due to the network structure providing restriction to mobility and diffusion of PLLA chains to crystal growth fronts. The mechanical properties show that FMWCNTs exhibit reinforcement effect for plasticized PLLA. Copyright © 2010 John Wiley & Sons, Ltd.     

Phase Transition in β-nucleated Isotactic Polypropylene Induced by Combination of Annealing and High Pressure

The effects of annealing and high pressure on the microstructure of β-nucleated isotactic polypropylene (iPP) were investigated. Annealing treatment was carried out at different temperatures from 90–170°C under different pressure conditions, that is, atmospheric pressure and high pressures of 150, 250, and 350 MPa, respectively. The microstructure of the specimens was comparatively investigated through using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Different from the common annealing treatment under atmospheric pressure, which induces the single-phase transition from metastable β-iPP to the more stable α-iPP (β→α) depending on the annealing temperatures, the application of high pressure induces not only the phase transition of β→α but also the phase transition of β→γ. Furthermore, the thermostability of β-iPP was improved greatly under high pressure. The higher the pressure applied, the smaller was the degree of the transition from β-iPP to α-iPP and/or γ-iPP. This work reports, for the first time, a novel crystalline morphology composed of β-iPP and γ-iPP.     

以啄木鸟玩具为例的LCP问题求解

啄木鸟玩具的运动是一个典型的工程力学线性互补问题．本文基于线性互补模型,结合开源Siconos软件,从实验、理论和模拟仿真上详细分析了啄木鸟玩具的运动过程．模拟仿真与实验结果均表明,啄木鸟玩具运动周期可细分为多个过程,初始激振条件的变化不会改变啄木鸟玩具稳定后的运动行为,而套筒与杆摩擦系数的改变会极大地影响啄木鸟的运动．本研究工作对工程力学中的线性互补问题具有很好的借鉴作用．     

(NaZSM-5)-AgI主体-客体纳米复合材料的研究

用热扩散法成功地把AgI组装于NaZSM5的孔道中,对制备的样品(NaZSM5)AgI进行了化学分析、粉末XRD分析、化学吸附、红外光谱表征,研究了所制备的样品固体扩散漫反射吸收光谱及发光性质.化学分析表明,AgI已进入NaZSM5主体中.粉末XRD分析显示了组装AgI后NaZSM5沸石骨架依然存在,红外光谱表明了(NaZSM5)AgI样品骨架振动与NaZSM5的骨架振动有细微差别,这主要是由组装了AgI引起的.吸附研究说明了AgI已进入NaZSM5的孔道.固体扩散漫反射吸收光谱表明,主体NaZSM5对制备的主体客体样品光吸收几乎没有影响,(NaZSM5)AgI的吸收光谱受AgI尺寸大小的影响.发光研究表明,制备的样品能带隙很高,辐射过程很强,(NaZSM5)AgI样品系具有发光功能的复合材料.     

过渡金属杂小环的扩环反应研究进展

过渡金属杂环化合物特别是过渡金属杂小环化合物(成环原子数小于6)在金属有机化学和配位化学领域中具有重要的地位,它们是许多过渡金属催化反应包括烯烃复分解反应、炔烃聚合反应的中间体.通常过渡金属杂小环化合物具有较大的环张力,因此极易与不饱和化合物反应生成环张力较小的扩环产物.针对过渡金属杂小环化学研究现状,综述了几类典型的过渡金属杂三、四、五元环的扩环反应.     

气相色谱-负化学电离源-飞行时间质谱测定烟草中有机氯农药残留

采用QuEChERS前处理方法,建立了气相色谱-负化学电离源-飞行时间质谱(GC-NCI-TOF-MS)检测烟草中10种有机氯农药残留的分析方法。样品采用乙酸乙酯-正己烷(1 : 1, v/v)溶液提取,提取液经N-丙基乙二胺(PSA)、无水硫酸镁分散固相萃取净化,用GC-NCI-TOF-MS检测分析。根据有机氯化合物特征离子的精确质量数、同位素离子峰簇、碎片离子丰度比和保留时间对目标物定性鉴定,外标法定量。10种有机氯农药的线性关系良好,相关系数 (r²)均大于0.997;相对标准偏差小于6.5%;检出限为0.04~0.80 μ g/kg;加标回收率为77.2%~93.0%。该方法简单快速、灵敏度高、准确性好,适用于烟草中有机氯农药残留的定性分析和定量检测。     

过氧钒配合物的合成、结构及模拟过氧化酶催化溴化动力学

根据模拟钒卤代过氧化物酶(V-HPOs)活性中心的配位环境,设计并合成了2种新型过氧钒配合物：Na[VO(O2)2(C10H8N2)]·8H2O(1)和K3H[(VO)2(O2)4(μ2-O)]·H2O(2),通过元素分析、红外光谱和紫外光谱对其进行了表征,并通过X射线单晶衍射方法确定了其结构。 配合物1晶体属于三斜晶系,空间群：P-1,a=0.7213(2) nm,b=1.1269(4) nm,c=1.3728(4) nm,α=68.349(4)°,β=89.178(4)°,γ=88.050(4)°,V=1.0365(6) nm3。 配合物2的晶体属于单斜晶系,空间群：P21/c,a=0.67047(12) nm,b=0.99503(18) nm,c=1.5817(3) nm,α=γ=90°,β=93.739(2)°,V=1.0530(3) nm3。 配合物1和2分别是五角双锥和八面体配位构型。 通过催化溴化反应活性研究发现,2种配合物均可作为潜在的钒卤代过氧化物酶模拟物。     

中国污染物排放强度的动态演进及空间收敛性研究

使用中国(不含港澳台地区)31个省级地区2001-2011年数据,利用空间面板模型对工业废水、化学需氧量、氨氮化物、工业二氧化硫、工业烟(粉)尘、工业废气和工业固体废物等七类污染物排放强度的地区差异性和空间收敛性进行了分析.研究结果表明:中国污染物排放强度存在着显著的空间相关性,各区域的污染物排放强度不满足绝对β收敛.人均GDP对污染物排放存在正的影响,第二产业比重存在负的影响,地区效应对收敛存在正相关效应.