Electrochemical investigations of baicalin and DNA–baicalin interactions

Baicalin is an anti-HIV drug purified from the traditional Chinese medicinal plant Scutellaria Baicalensis Georgi. Baicalin has proven to be electroactive at pyrolytic graphite (PG) electrodes. We thus studied its interaction with DNA via the electrochemical approach. We observed that the peak currents corresponding to the baicalin reduction–oxidation (redox) reaction significantly decrease upon the addition of DNA. With complementary ultraviolet/visible (UV/Vis) spectroscopic evidence, we suggest that baicalin binds to DNA through intercalation. This feature has enabled baicalin to discriminate between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA).Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Investigation of energy and structural changes of Lin (n=3, 4) microclusters based on temperature

The energy and structural changes of lithium microclusters based on temperature has been investigated by using Molecular-Dynamic simulation Method. Two and three-body interacted semi-empiric potential energy formula that characterized the interaction has been used. It has been calculated that the dissociation of atoms from cluster has started after 1300 K for Li₃ and 1350 K for Li₄, respectively. Dissociations at the fixed temperatures are very close to the expected values of the lithium metal. Additionally, it has been observed that Li₄ microclusters above 1000 K and Li₃ clusters above 700 K temperatures have steady structures in two different energy values.     

可见光谱法研究核酸酶P1与氯化铜(Ⅱ)的相互作用

首次采用ＶＩＳ与酶活性测定的方法,研究了溶液中核酸酶Ｐ１与无机氯化铜（Ⅱ）（ＣｕＣｌ２）的直接相互作用。结果发现：在水溶液中核酸酶Ｐ１活性中心的Ｚｎ（Ⅱ）离子可被外加氯化铜（ＣｕＣｌ２）中的Ｃｕ（Ⅱ）部分诱导、交换出来,而Ｃｕ（Ⅱ）进入酶的活性中心,形成相应“Ｃｕ（Ⅱ）－Ｐ１”酶衍生物,并随着溶液ｐＨ值的变化,形成酶的衍生物结构亦随之变化,相应地也影响了酶的催化活性。     

Molecular simulation of the interaction between novel type rhodanine derivative probe and bovine serum albumin

The interaction between 3-(4′-methylphenyl)-5-(4′-methyl-2′-sulfophenylazo) rhodanine (M4MRASP) and bovine serum albumin (BSA) was studied by using spectrofluorimetry. It was shown in fluorescence spectrums that the quenching mechanism of BSA by M4MRASP was a static quenching. Meanwhile, the binding constant and binding site numbers were calculated. The action distance (r = 8.03 nm) and energy transfer efficiency (E = 0.12) between donor (BSA) and acceptor (M4MRASP) were obtained according to the theory of Förster non-radiation energy transfer. The effect of M4MRASP on the conformation of BSA was further analyzed by using synchronous fluorescence spectrometry. A new model of the interaction between small organic molecule and biomacromolecule was established. The results offered a reference for the studies on the biological effects and action mechanism of small molecule with protein.     

INTERACTION CURVES OF LINEARLY INTENSIFYING POLYMERIC MATERIALS UNDER TENSILE-TORSIONAL STRESS

Theoretical and experimental research has been performed on the interaction curves and stress paths of crystallinepolymeric materials PE and POM under tensile-torsional stress with a linearly intensifying model and in terms of the yield points undergoing Von Mises criterion.     

Comparative study of natural rubber/clay nanocomposites prepared from fresh or concentrated latex

Rubbers are usually compounded with different chemicals and fillers in order to modify their properties to suit the end applications. Natural rubber (NR) contains different natural occurring materials and this brings about subtle complexities in controlling compound and vulcanizate properties. Thus, the aim of this paper is to illustrate that the properties of compounds and vulcanizates of NR/clay prepared from fresh field latex and from concentrated latex are different. Different amounts of pristine clay were added to the two latices and their viscosity determined. The latex mixtures were next coagulated to form solid filled rubbers and their properties examined. Vulcanizates of these solid rubbers were then prepared and their properties, also, were determined. The cause of an observed variation is attributed to soluble proteins in the fresh field latex. Structural models to explain this are proposed.     

中厚度圆浮板自由振动的一个解析解

本文提出了常水深环境下中厚度圆浮板自由振动的一个解析解.分析中考虑了板横向剪切变形的影响和横截面转动惯性效应,利用空气中中厚度圆板的振型叠加和势流理论,导得了浮板系统频率方程的解析式.由此可看出Y.Tanaka得到的圆形薄浮板的解是本文的特例.最后数值计算还给出了水深和钢缆刚度与频率的关系曲线.并指出了h/a在什么范围可以略去剪切变形和转动惯量的影响.     

Conformation of aromatic rings in isolable atropisomers of 2-arylindoline derivatives and kinetic evidences for π-π interaction

The equilibrium constants [K=anti/syn] of a pair of atropisomers due to restricted rotation about Csp³-Csp² bond for [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethylindolin-1-yl](4-substituted phenyl)methanone were determined in some solvents. The presence of the effective π-π interaction was demonstrated by the correlation between the equilibrium constants (K) and the substituent effect of the phenyl groups (σ_p), suggesting that the ‘neutral-type’ interaction is operative.     

Adsorption interaction parameter of polyethers in ternary mobile phases: The critical adsorption line

It is shown that in LC of polymers, the interaction parameter in ternary mobile phases can be described by a plane, which is determined by the dependencies in binary mobile phases. Instead of a critical adsorption point, critical conditions are observed along a straight line of composition between the two critical points in binary mobile phases. Consequently, a separation of block copolymers under critical conditions for one block by an adsorption mechanism for the other block can be achieved in ternary mobile phases of different compositions, which allows an adjustment of the retention of the adsorbing block.