Application of the crystallographic orbit analysis to the study of twinned crystals. The example of marcasite

The continuity of a substructure across the interface is considered a necessary condition for the formation of a twin. The application of the analysis of the eigensymmetry of crystallographic orbits to the derivation of this structural continuity is briefly reviewed and applied to the analysis of the {101} twin in marcasite. This analysis shows that one fourth of the structure, but half of the substructure near the composition surface, is common to the two orientations realized in the twin, the operation mapping the common atoms in the twinned domains being an n‐glide occurring every one fourth of the period along the direction quasi‐perpendicular to the twin plane. The existence of this significant common substructure justifies and explains the formation of the twin.     

Using grey dynamic modeling and pseudo amino acid composition to predict protein structural classes

Using the pseudo amino acid (PseAA) composition to represent the sample of a protein can incorporate a considerable amount of sequence pattern information so as to improve the prediction quality for its structural or functional classification. However, how to optimally formulate the PseAA composition is an important problem yet to be solved. In this article the grey modeling approach is introduced that is particularly efficient in coping with complicated systems such as the one consisting of many proteins with different sequence orders and lengths. On the basis of the grey model, four coefficients derived from each of the protein sequences concerned are adopted for its PseAA components. The PseAA composition thus formulated is called the "grey-PseAA" composition that can catch the essence of a protein sequence and better reflect its overall pattern. In our study we have demonstrated that introduction of the grey-PseAA composition can remarkably enhance the success rates in predicting the protein structural class. It is anticipated that the concept of grey-PseAA composition can be also used to predict many other protein attributes, such as subcellular localization, membrane protein type, enzyme functional class, GPCR type, protease type, among many others.     

Bricks and pseudo MV-algebras are equivalent

We will show that the bricks (of Bosbach) and the pseudo MV-algebras are each term equivalent to the class of semigroups with a pair of unary operations ^ and ˘ satisfying the equations: (aa)^b = b = b(aă)˘ and a( a)˘ = (bă)^b and also show that a brick is an interval [0, u] of the positive cone of a unital lattice ordered group. We further extend the notion of implications to a pseudo MV-algebra and study the algebra of such implications.      

一种假冠醚聚合物POCE的合成与性能

吸附;红外光谱;一种假冠醚聚合物POCE的合成与性能     

聚合物假冠醚研究(IV) 酚醛型双氮杂假冠醚聚合物的吸附特性

研究了以双氮杂假冠醚环为主体功能基的酚醛型聚合物对金属离子的吸附性能．结果表明，聚合物对K ，Hg2 ，Na ，Cd2 ，Pb2 和Cu2 离子具有良好的吸附性能，其吸附容量分别达1．79mmol／g-r，1．38mmol／g-r，0．89mmol／g-r，0．68mmol／g-r，0．63mmol／g-r和0．57mmol／g-r，对K 和Hg2 离子具有良好的吸附选择性．通过FTIR光谱法对吸附机理作了初步探讨．     

Phase Behavior of n‐Butanol/n‐Octane/Water/Cationic Gemini Surfactant System

Phase diagrams of the n‐butanol/n‐octane/water/(12‐3‐12,2Br^?1) system were determined, where n‐octane usually represents oil (O), 12‐3‐12,2Br^?1 is a gemini cationic surfactant trimethylene‐1,3‐bis(dodecyldimethyl ammonium bromide) abbreviated as S, and n‐butanol is a co‐surfactant written as A. Effects of the weight ratio of gemini surfactant to cosurfactant, S/A, and of temperature on the phase behavior were studied. The microemulsion structures including O/W, bi‐continuous (B.C.), W/O, and liquid crystal were determined by the conductivity method and polarization measurement. Experimental results show that the gemini surfactant, used facilitates the formation of microemulsions compared with its corresponding monomeric surfactant, n‐dodecyl trimethylammonium bromide (DTAB). When S/A=1/1, and the total concentration of gemini surfactant and alcohol is 20–40%, microemulsions with higher water content can form in a wider region. When the temperature increases, the size and position of each type of microemulsion region changes notably.     

环糊精超分子水凝胶

本文综述了近年来基于环糊精包合作用的超分子水凝胶的研究进展,主要包括：环糊精与线性、星型、接枝、超支化聚合物包合形成的多聚(准)轮烷自组装制备超分子物理凝胶及功能化多聚(准)轮烷经交联反应制备超分子化学凝胶;环糊精、环糊精二聚体及其水溶性聚合物与带疏水性侧基的聚合物经“锁-钥匙”包合作用形成超分子物理凝胶;及其在药物、基因释放载体与组织工程支架中的应用。着重介绍了剪切、温度、pH值、光等刺激-响应性超分子水凝胶的设计与制备。     

GPCR‐CA: A cellular automaton image approach for predicting G‐protein–coupled receptor functional classes

Given an uncharacterized protein sequence, how can we identify whether it is a G‐protein–coupled receptor (GPCR) or not? If it is, which functional family class does it belong to? It is important to address these questions because GPCRs are among the most frequent targets of therapeutic drugs and the information thus obtained is very useful for “comparative and evolutionary pharmacology,” a technique often used for drug development. Here, we present a web‐server predictor called “GPCR‐CA,” where “CA” stands for “Cellular Automaton” (Wolfram, S. Nature 1984, 311, 419), meaning that the CA images have been utilized to reveal the pattern features hidden in piles of long and complicated protein sequences. Meanwhile, the gray‐level co‐occurrence matrix factors extracted from the CA images are used to represent the samples of proteins through their pseudo amino acid composition (Chou, K.C. Proteins 2001, 43, 246). GPCR‐CA is a two‐layer predictor: the first layer prediction engine is for identifying a query protein as GPCR on non‐GPCR; if it is a GPCR protein, the process will be automatically continued with the second‐layer prediction engine to further identify its type among the following six functional classes: (a) rhodopsin‐like, (b) secretin‐like, (c) metabotrophic/glutamate/pheromone; (d) fungal pheromone, (e) cAMP receptor, and (f) frizzled/smoothened family. The overall success rates by the predictor for the first and second layers are over 91% and 83%, respectively, that were obtained through rigorous jackknife cross‐validation tests on a new‐constructed stringent benchmark dataset in which none of proteins has ≥40% pairwise sequence identity to any other in a same subset. GPCR‐CA is freely accessible at http://218.65.61.89:8080/bioinfo/GPCR‐CA , by which one can get the desired two‐layer results for a query protein sequence within about 20 seconds. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009     

Synthesis of 18F‐Difluoromethylarenes from Aryl (Pseudo) Halides

A general method for the synthesis of [¹⁸F]difluoromethylarenes from [¹⁸F]fluoride for radiopharmaceutical discovery is reported. The method is practical, operationally simple, tolerates a wide scope of functional groups, and enables the labeling of a variety of arenes and heteroarenes with radiochemical yields (RCYs, not decay‐corrected) from 10 to 60 %. The ¹⁸F‐fluorination precursors are readily prepared from aryl chlorides, bromides, iodides, and triflates. Seven ¹⁸F‐difluoromethylarene drug analogues and radiopharmaceuticals including Claritin, fluoxetine (Prozac), and [¹⁸F]DAA1106 were synthesized to show the potential of the method for applications in PET radiopharmaceutical design.     

聚合物在胶束电动色谱中的应用

本文回顾了自1992 年聚合物第一次被用作胶束电动色谱准固定相以来聚合胶束、聚合物表面活性剂和枝状高分子在这方面的研究进展, 并与常用表面活性剂的性能进行了对比。