Narrow Results

Bioinformatics plays an important role for in the research and development of the life science and biotechnology. This paper intends to give an overview of the activities of bioinformatics service, research and education at the Center of Bioinformatics, Peking University; the national node of the European Molecular Biology Network and the Asia Pacific Bioinformatics Network.

The aneurysm of iliac artery is a rare entity and there are few computational models that have studied the disease. In this study, we have presented the flow patterns in the aneurysmal artery using Fluid–structure interaction method. The blood was assumed Newotonian, pulsatile, laminar, incompressible, and homogenous. The geometry of the model was made based on CT images of clinical cases. Using the computational method, we have obtained the velocity and pressure contours, shear rates and vortices for the healthy and aneurysmal artery. The results show that a pressure maximum was found at the midpoint of the dilation. The vortices are formed in the aneurysmal area²⁶ and shear rates do not change much. However, the rate increased in the neck of aneurysms. Furthermore, the aneurysm with bigger dilation tend to rupture due to more shear rates in the neck and the velocity at peak systole decreases in the aneurysmal area due to increase of the artery diameter. We have compared our results with some available relevant clinical data in discussion section.

Ketenes are excellent precursors for catalytic asymmetric reactions, creating chiral centers mainly through addition across their C=C bonds. Density functional theory (DFT) calculations at the MO6/LACVP* and B3LYP/LACVP* levels of theory were employed in a systematic investigation of the peri-, chemo- and regio-selectivity of the addition of transition metal oxo complexes of the type ReO₃L(L=Cl^-, O^-, OCH₃, CH₃) to substituted ketenes O=C=C(CH₃)(X) [X=CH₃, H, CN, Ph] with the aim of elucidating the effects of substituents on the mechanism of the reactions. The [2 + 2] addition pathway across the C=C or C=O (depending on the ligand) is the most preferred in the reactions of dimethyl ketene with all the metal complexes studied. The [2 + 2] pathway is also the most preferred in the reactions of ReO₃Cl with all the substituted ketenes studied except when X=Cl. Thus of all the reactions studied, it is only the reaction of ReO₃Cl with O=C=C(CH₃)(Cl) that prefers the [3 + 2] addition pathway. Reactions of dimethyl ketene with ReO₃L favors addition across C=O bonds of the ketene when L=O^- and CH₃ but favors addition across C=C bonds when L=OCH₃ and Cl. In the reactions of ReO₃Cl with substituted ketenes, addition across C=O bonds is favored only when X=H while addition across C=C bonds is favored when X=CH₃, Cl, Ph, CN. The reactions of dimethyl ketene with ReO₃L will most likely lead to the formation of an ester precursor in each case. A zwitterionic intermediate is formed in the reactions except in the reactions of . The order in the activation energies of the reactions of dimethyl ketenes with the metal complexes ReO₃L with respect to changing ligand L is O^- < CH₃O^- < Cl^- < CH₃ while the order in reaction energies is CH₃ < CH₃O^- < O^- < Cl^-. For the reactions of substituted ketenes with ReO₃Cl, the order in activation barriers is CH₃ < Ph < CN < Cl < H while the reaction energies follow the order Cl < CH₃ < H < Ph < CN. In the reactions of dimethyl ketenes with ReO₃L, the trend in the selectivity of the reactions with respect to ligand L is Cl^- < CH₃O^- < CH₃ < O^- while the trend in selectivity is CH₃ < CN < Cl < Ph in the reactions of ReO₃Cl with substituted ketenes. It is seen that reactions involving a change in oxidation state of metal from the reactant to product have high activation barriers while reactions that do not involve a change in oxidation state have low activation barriers. For both [3 + 2] and [2 + 2] additions, low activation barriers are obtained when the substituent on the ketene is electron-donating while high activation barriers are obtained when the substituent is electron-withdrawing.

Rett Syndrome is a rare genetic disorder exclusively seen in girls. Approximately 95% of RTT cases is caused by mutations in the MeCP2 gene which codes for Methyl-CpG-binding protein 2 (MeCP2). In this review, first, a brief introductory review of Rett Syndrome, MeCP2 protein structure and function, mutation types and frequencies, and phenotype–genotype relationships were provided. After that, the current knowledge on the wild-type and mutant MeCP2 protein structure and dynamics as well as its binding to DNA is reviewed. The review particularly focuses on computational (such as molecular dynamics) and experimental (such as electrophoretic mobility shift assays) studies on the MeCP2 binding to different types of DNA as well as the computational and experimental (such as circular dichroism) studies on the stability changes upon mutations. In the end, a brief opinion on future outlook for further computational studies is provided.

Metal matrix composites (MMCs) have been regarded as one of the most principal classifications in composite materials. The thermal characterization of hybrid MMCs has been increasingly important in a wide range of applications. The coefficient of thermal expansion is one of the most important properties of MMCs. Since nearly all MMCs are used in various temperature ranges, measurement of coefficient of thermal expansion (CTE) as a function of temperature is necessary in order to know the behavior of the material. In this research paper, the evaluation of thermal expansivity has been accomplished for Al 6061, silicon carbide (SiC) and Graphite (Gr) hybrid MMCs from room temperature to 300°C. Aluminum (Al)-based composites reinforced with SiC and Gr particles have been prepared by stir casting technique. The thermal expansivity behavior of hybrid composites with different percentage compositions of reinforcements has been investigated. The results have indicated that the thermal expansivity of the different compositions of hybrid MMCs decreases by the addition of Gr with SiC and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity of composites. Using the experimental values namely modulus of elasticity, Poisson's ratio and thermal expansivity, computational investigation has been carried out to evaluate the thermal parameters namely thermal displacement, thermal strain and thermal stress.

Metal matrix composites (MMCs) are regarded to be one of the most principal classifications in composite materials. The thermal characterization of hybrid MMCs has become increasingly important in a wide range of applications. Thermal conductivity is one of the most important properties of MMCs. Since nearly all MMCs are used in various temperature ranges, measurement of thermal conductivity as a function of temperature is necessary in order to know the behavior of the material. In the present research, evaluation of thermal conductivity has been accomplished for aluminum alloy (Al) 6061, silicon carbide (SiC) and graphite (Gr) hybrid MMCs from room temperature to $300^{\circ }$C. Al-based composites reinforced with SiC and Gr particles have been prepared by stir casting technique. The thermal conductivity behavior of hybrid composites with different percentage compositions of reinforcements has been investigated using laser flash technique. The results have indicated that the thermal conductivity of the different compositions of hybrid MMCs decreases by the addition of Gr with SiC and Al 6061. Few empirical models have been validated concerning with the evaluation of thermal conductivity of composites. Using the experimental values namely density, thermal conductivity, specific heat capacity and enthalpy at varying temperature ranges, computational investigation has been carried out to evaluate the thermal gradient and thermal flux.

The thermal characterization and analysis of composite materials has been increasingly important in a wide range of applications. The coefficient of thermal expansion (CTE) is one of the most important properties of metal matrix composites (MMCs). Since nearly all MMCs are used in various temperature ranges, measurement of CTE as a function of temperature is necessary in order to know the behavior of the material. In this research paper, the evaluation of CTE or thermal expansivity has been accomplished for Al 6061, silicon carbide and graphite hybrid MMCs from room temperature to $300^{\circ }$C. Aluminium-based composites reinforced with silicon carbide and graphite particles have been prepared by stir casting technique. The thermal expansivity behavior of hybrid composites with different percentage compositions of reinforcements has been investigated. The results have indicated that the thermal expansivity of different compositions of hybrid MMCs decrease by the addition of graphite with silicon carbide and Al 6061. Empirical models have been validated for the evaluation of thermal expansivity of composites. Numerical convergence test has been accomplished to investigate the thermal expansion behavior of composites.

In this research paper, the determination of thermal expansivity and thermal conductivity has been accomplished for Al 6061, Silicon Carbide and Graphite hybrid metal matrix composites from room temperature to $300^{\circ }$C. Aluminium-based composites reinforced with Silicon Carbide and Graphite particles have been prepared by stir casting technique. The thermal expansion and thermal conductivity properties of hybrid composites with different percentage compositions of reinforcements have been investigated. The results have indicated that the thermal expansivity and thermal conductivity of the different compositions of hybrid MMCs decrease by the addition of Graphite with Silicon Carbide and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity and thermal conductivity of hybrid composites. Using the experimental values, namely modulus of elasticity, Poisson ratio and thermal expansivity, computational investigation has been carried out to evaluate the thermal parameters, namely thermal displacement, thermal strain and thermal stress. Similarly, using the experimental values, namely density, thermal conductivity, specific heat capacity and enthalpy at varying temperature ranges, computational investigation has been carried out to evaluate thermal gradient and thermal flux.

The geometric effect of single-walled carbon nanotube (CNT) on mechanical performances of epoxy nanocomposites was investigated under different loading conditions. The reactive force field (ReaxFF) and optimum liquid potential simulator (OPLS) were used in the computational molecular dynamics simulation. The analysis comprises the methodology employed to model the equilibrated structures of CNT/epoxy nanocomposites and characterizes elastic parameters of the structures. The computational results showed that the chirality of the CNTs affects the mechanical performances of the nanocomposites.

This study investigated the microscale behaviours and damage evolutions of graphene/epoxy nanocomposites under uniaxial tensile loadings. Computational molecular dynamics (MD) simulation was applied to model the microstructural constituents of graphene/epoxy composites and the evaluation of their mechanical and the damage responses at different temperatures. The computed results revealed the influence of the proportions of graphene and temperatures on the mechanical properties, the damage evolution and the change in strain energy associated with failure of the nanocomposites. The study has added to the understanding of the damage development and failure of the graphene nanoplatelets (GNP)/epoxy composites.

Rett Syndrome is a rare genetic disorder exclusively seen in girls. Approximately 95% of RTT cases is caused by mutations in the MeCP2 gene which codes for Methyl-CpG-binding protein 2 (MeCP2). In this review, first, a brief introductory review of Rett Syndrome, MeCP2 protein structure and function, mutation types and frequencies, and phenotype– genotype relationships were provided. After that, the current knowledge on the wild-type and mutant MeCP2 protein structure and dynamics as well as its binding to DNA is reviewed. The review particularly focuses on computational (such as molecular dynamics) and experimental (such as electrophoretic mobility shift assays) studies on the MeCP2 binding to different types of DNA as well as the computational and experimental (such as circular dichroism) studies on the stability changes upon mutations. In the end, a brief opinion on future outlook for further computational studies is provided.