聚醚树枝体线性聚(N-异丙基丙烯酰胺)不对称嵌段共聚物的 合成及自组装

采用原子转移聚合方法合成了聚N-异丙基丙烯酰胺和聚醚树技体的不对嵌段共聚物Dendr.PE-PNI-PAM。实验结果表明Dendr.PE-PNIPAM分子在水中能通过疏水缔合作用形成具有双分子膜结构的超分子聚集体。临界缔合浓度(CAC)、聚集体的大小及形貌对树枝体的代数具有明显的依赖关系。该聚集体对温度刺激具有响应性,并在人体体温温度(37.5℃)发生相转变。在高于相转变温度时,Dendr.PE-PNIPAM分子形成管状、带状等多重形态的超级结构的聚集体。     

Effect of low-molecular-weight organic anions on surface charge of variable charge soils

Low-molecular-weight (LMW) organic acids exist widely in soils and have been implicated in many soil processes. In the present paper, the effect of the anions of four low-molecular-weight organic acids on the surface charge of three variable charge soils was investigated. The results showed that the presence of organic anions led to an increase in negative charge and a decrease in positive charge. Positive charges decreased to a larger extent than negative charges. The effect of different anions on surface charge followed the order citrate > malate > oxalate > acetate. For hyper-rhodic ferrasol and rhodic ferrasol, the change of positive charge decreased with the increase in pH, while that of negative charge increased with the increase in pH. Among different soils the extent of change in surface charge was related to their iron oxides content. When free iron oxides were removed from the soil, the effect of organic anions on surface charge decreased sharply. These findings may be of practical significance for variable charge soils low in nutrient-retaining capacity by increasing the retaining capacity for cations such as potassium and calcium considerably but decreasing that for anions such as nitrate remarkably.     

气相色谱中保留值与进样量的关系

提出了测量气相色谱中吸附等温线的新方法，用不同进样量下测定的容量因子计算平衡时气-固两相组分浓度。利用建立的方法分别测量了正-己烷、正-壬烷和正-十一烷在邻苯二甲酸二辛酯(DOP)、阿皮松-L(Apiezon)和β，β′-氧二丙腈(ODPN)柱上的吸附等温线，讨论了色谱峰形状与吸附等温线的对应关系。研究了气相色谱中进样量对保留值的影响，利用佛伦德利希(Freundlich)吸附等温式导出了描述保留值与进样量关系的数学表达式。理论和实验证明，保留值与进样量具有良好的对数线性关系。     

先进的微生物芯片检测系统及其应用

发展了一种先进的微生物芯片检测方法,并研制用于芯片检测的新型数字化成像扫描检测系统。采用激光诱导荧光的检测原理设计一种新颖的CCD数字化成像扫描检测系统结构,荧光信号采集端的数值孔径NA=0．72,工作距离3．22 mm,系统检测灵敏度小于每平方微米1个荧光分子。以微生物大肠杆菌和黄单胞菌检测为例,设计基因芯片,并应用所研制的芯片检测系统实现了微生物的正确鉴定,提供了一种高效的食品安全检测整体解决方法。实验结果表明两种微生物的芯片检测实验结果稳定可靠,与国外共焦扫描仪检测的结果完全一致。     

Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.     

Iterative solutions to coupled Sylvester-transpose matrix equations

This note studies the iterative solutions to the coupled Sylvester-transpose matrix equation with a unique solution. By using the hierarchical identification principle, an iterative algorithm is presented for solving this class of coupled matrix equations. It is proved that the iterative solution consistently converges to the exact solution for any initial values. Meanwhile, sufficient conditions are derived to guarantee that the iterative solutions given by the proposed algorithm converge to the exact solution for any initial matrices. Finally, a numerical example is given to illustrate the efficiency of the proposed approach.     

Spectral theory of left definite difference operators

This paper is concerned with the spectral theory for the second-order left definite difference boundary value problems. Existence of eigenvalues of boundary value problems is proved, numbers of their eigenvalues are calculated and fundamental spectral results are obtained.     

强外电场作用下二甲基硅酮的分子结构和激发态

采用密度泛函(DFT)方法B3P86在6 311++G(d,p)基组水平上优化得到了分子轴方向不同电偶极 场(-0.04～0.04a.u.)作用下,二甲基硅酮的基态电子状态、几何结构、电偶极矩和分子总能量.在优化构型下 用同样的基组采用杂化CIS DFT方法(CIS B3P86)研究了同样外电场条件下对二甲基硅酮的激发能和振子强度 的影响.计算结果表明,分子几何构型与电场大小和方向呈现强烈的依赖,正向电场下基态偶极矩随电场强度线 性增加,分子总能量降低,当反向电场大于0.03a.u.时,偶极距方向改变,总能量增加;激发能随电场增加急剧减 小,且对电场方向的依赖呈现出不对称性,满足Grozema关系.电场对振子强度的影响比较复杂,但仍满足跃迁选 择定则.     

The application with tetramethyl pyrazine for antithrombogenicity improvement on silk fibroin surface

Chuanxiongqin (tetramethyl pyrazine, TMPZ) is an active ingredient of the Chinese herb and was used to improve the anticoagulant activity of silk fibroin (SF). The side methyl of TMPZ was oxidized, and then linked to polyacrylic acid (PAA) via an ester bond. The prepared conjugate was further mixed with SF solutions at different ratios to make blend films. The resulting products were characterized by FTIR, UV spectrometer and X-ray photoelectron spectroscopy (XPS). The in vitro antithrombogenicity were evaluated by the activated partial thromboplastin time (APTT) and the prothrombin time (PT). It was shown that blend films had longer coagulation time than the pure SF film.