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EXTENDED core structure OF DISSOCIATED EDGE DISLOCATIONS IN FCC CRYSTALS WITH CONSIDERATION OF DISCRETENESS

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Acta Mechanica Solida Sinica 2008年第5期21卷 403-410页

作者： Xiaozhi Wu Shaofeng Wang Huili Zhang Institute for structure and Function Chongqing University Chongqing 400044 China

The extended core structure of the dissociated edge dislocation in Al, Au, Ag, Cu and Ni is determined within lattice theory of dislocation. The 2D dislocation equation governing the displacements is coupled by the restoring forces that are determined by the parameterization of the generalized stacking fault energies. The Ritz variational method is presented to solve the dislocation equation and the trial solution is constituted by two arctan-type functions with two undetermined parameters. The core widths of partial dislocations are wider than that obtained in generalized Peierls-Nabarro model due to the consideration of discreteness of crystal.

关键词： core structure dissociation dislocation equation variational method

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On the core structure and mobility of the〈100 〉{010} and〈100 〉 {01■} dislocations in B2 structure YAg and YCu

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Chinese Physics B 2009年第7期18卷 2905-2911页

作者：吴小志王少峰刘瑞萍 Institute for structure and Function Chongqing University

Dislocations are thought to be the principal mechanism of high ductility of the novel B2 structure intermetallic compounds YAg and YCu.In this paper, the edge dislocation core structures of two primary slip systems 〈100〉{010} and 〈100〉{01^-1} for YAg and YCu are presented theoretically within the lattice theory of dislocation.The governing dislocation equation is a nonlinear integro-differential equation and the variational method is applied to solve the equation.Peierls stresses for 〈100〉{010} and 〈100〉{01^-1} slip systems are calculated taking into consideration the contribution of the elastic strain energy.The core width and Peierls stress of a typical transition-metal aluminide NiAl is also reported for the purpose of verification and comparison.The Peierls stress of NiAl obtained here is in agreement with numerical results,which verifies the correctness of the results obtained for YAg and YCu.Peierls stresses of the 〈100〉{01^-1} slip system are smaller than those of 〈100〉{010} for the same intermetallic compounds originating from the smaller unstable stacking fault energy.The obvious high unstable stacking fault energy of NiAl results in a larger Peierls stress than those of YAg and YCu although they have the same B2 structure.The results show that the core structure and Peierls stress depend monotonically on the unstable stacking fault energy.

关键词： YAg YCu core structure Peierls stress

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Atomistic Simulation of Undissociated 60°Basal Dislocation in Wurtzite GaN.

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Modeling and Numerical Simulation of Material Science 2013年第4期3卷 11-16页

作者： I.Belabbas J.Chen Ph.Komninou G.Nouet Groupe de Cristallographie et de Simulation des Matériaux Laboratoire de Physico-Chimie des Matériaux et Catalyse.Universite Abderrahmane MiraBejaia(06000)Algérie CIMAP UMR6252 CNRS-CEA-ENSICAEN-Universite de Caen Basse-Normandie14032France Department of Physics Aristotle University of ThessalonikiGR-54124 ThessalonikiGreece Centre de Recherche sur les Ions les Matériaux et la Photonique6 Boulevard du Maréchal Juin14050 Caen cedexFrance

We have carried out computer atomistic simulations, based on an efficient density functional based tight binding method, to investigate the core configurations of the 60°basal dislocation in GaN wurtzite. Our energetic calculations, on the undissociated dislocation, demonstrate that the glide configuration with N polarity is the most energetically favorable over both the glide and the shuffle sets.

关键词： Gallium Nitride 60°Basal Dislocation core structure Energy Tight-binding SCC-DFTB

TWO-TIME SCALES INNER SOLUTIONS AND MOTION OF A GEOSTROPHIC VORTEX

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Science in China,Ser.A 1988年第7期 806-817页

作者：凌国灿丁汝

Based on the authors’ previous work, in this paper the systematical analyses on the motion and the inner solutions of a geostrophic vortex have been presented by means of thematched asymptotic expansion method with multiple time scales (S/gh001/2 and α S/gh001/2) and space scales. It has been shown that the leading inner solutions to the core structure in two-time scales analyses are identified with the results in normal one-time scale analyses. The time averages of the first-order solutions on short time variable τ are the same as the first-order solutions obtained in one normal time scale analyses. The geostrophic vortex induces an oscillatory motion in addition to moving with the background flow. The period, amplitude andthe deviation from the mean trajectory depend on the core structure and the initial conditions. The velocity of the motion of vortex center varies periodically and the time average of the velocity on short time variable τ is equal to the value of the local mean velocit

关键词： geostrophic vortex core structure trajectory.

Synthesis and structure Elucidation of Celangulin Derivatives

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有机化学 2004年第Z1期24卷 302-页

作者： ZHANG,Ji-Wen WU,Wen-Jun TIAN,Xuan Institute of Pesticide Science Northwest Sci-Tech University of Agriculture and Forest Yangling 712100 College of Life Science Northwest Sci-Tech University of Agriculture and Forest Yangling 712100 Institute of Pesticide Science Northwest Sci-Tech University of Agriculture and Forest Yangling 712100 National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000

　　Celangulins are sesquiterpene polyol esters based on a core structure known as β-dihydroagarofuran from Celastrus angulatus Max. Some of them are environment acceptable-pesticides. In order to find new active compounds and study their SAR, sesquiterpene polyol esters libraries were synthesized based on the basic hydrolysis of the extract of the root bark of Celastrus angulatus which could offer the β-dihydroagarofuran polyol by combinatorial chemical method and the compounds with insecticidal activity were isolated by bioassay-guided fractionation. Two new compounds with insecticidal activity against Mythimna separata, were isolated and elucidated as 2β,6α,8β, 13-tetraisobutanoyloxy-1β,4,9α-trihydroxy-β-dihydroagarofuran (A) and 1β,2β,6α,8β, 13-pentaisobutanoyloxy-4α,9α-dihydroxy-β-dihydroagarofuran (B) mainly by 1H NMR, 13C NMRH-HCOSY, HMQC, HMBC and HRMS spectral data. A: [α]20D -7.3 (c 0.12, CHCl3), B: [α]20D -34.6 (c 0.8,CHCl3).……

关键词： insecticidal activity Celastrus angulatus chemical method core structure spectral data root bark

Homology modeling of lanosterol 14alpha-demethylase of Candida albicans and Aspergillus fumigatus and insights into the enzyme-substrate interactions

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第二军医大学学报 2005年第2期26卷 173-173页

作者： Sheng C Zhang W Zhang M Song Y Ji H Zhu J Yao J Yu J Yang S Lu J School of Pharmacy Second Military Medical University Shanghai 200433 China

The crystal structure of 14alpha-sterol demethylase from Mycobacterium tuberculosis (MT_14DM) provides a good template for modeling the three dimensional structure of lanosterol 14alpha-demethylase, which is the target of azole antifungal agents. Homologous 3D models of lanosterol 14alpha-demethylase from Candida albicans (CA_14DM) and Aspergillus fumigatus (AF_14DM) were built on the basis of the crystal coordinates of MT_14DM in complex with 4-phenylimidazole and fluconazole. The reliability of the two models was assessed by Ramachandran plots, Profile-3D analysis, and by analyzing the consistency of the two models with the experimental data on the P450(14DM). The overall structures of the resulting CA_14DM model and AF_14DM model are similar to those of the template structures. The two models remain the core structure characteristic for cytochrome P450s and most of the insertions and deletions expose the molecular surface. The structurally and functionally important residues such as the heme binding residues, the residues lining the substrate access channel, and residues in active site were identified from the model. To explore the binding mode of the substrate with the two models, 24(28)-methylene-24,25-dihydrolanosterol was docked into the active site of the two models and hydrophobic interaction and hydrogen-bonding were found to play an important role in substrate recognition and orientation. These results provided a basis for experiments to probe structure-function relationships in the P450(14DM). Although CA_14DM and AF_14DM shared similar core structural character, the active site of the two models were quite different, thus allowing the rational design of specific inhibitors to the target enzyme and the discovery of novel antifungal agents with broad spectrum.

关键词： active site Mycobacterium tuberculosis hydrophobic interaction three dimensional molecular surface experimental data crystal structure Candida albicans the consistency rational design core structure mode of

Discovery and structure-Based Design of Novel Selective Estrogen Receptor Modulators（SERMs）

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Discovery and Structure-Based Design of Novel Selective Estr...