First-principle study on the electronic structure of stressed CrSi<Subscript>2</Subscript>

The electronic structure of stressed CrSi₂ was calculated using the first-principle methods based on plane-wave pseudo-potential theory. The calculated results showed that, under the uniaxial compression, the energy level of CrSi₂ shifted toward high energy and its energy gap became wider with the increasing uniaxial stress, while the gap became narrower under the negative uniaxial stress. When the negative uniaxial stress was up to −18.5 GPa, CrSi₂ was converted into a direct-gap semiconductor with the band gap of 0.32 eV. Supported by the National Natural Science Foundation of China (Grant No. 60566001), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050657003), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China (Grant No. (2005)383), the Program for the Excellent Young Talents of Guizhou Province (Grant No. 20050528), the Specialized Nomarch Research Fund for the Excellent Science and Technology and Education Talent’s Projects of Guizhou Province, Scientific and Technological Projects for the Returned Overseas Chinese Scholars, the Guizhou Province (Grant No. (2004)03), and the Top Talent’s Scientific Research Project of Organization Department of Guizhou Province     

Synthesis,Crystal Structures and Properties of Two Novel Co（Ⅱ） and Cd（Ⅱ） Complexes of N-AcetyI-L-glutamic Acid and Imidazole Ligands

Two novel complexes {[Co（A-glu）（Im）2]·0.5H2O}n （1） and [Cd（A-glu）（Im）3]n （2） （H2A-glu=N-acetyl-L-glutamic acid, Im=imidazole） have been synthesized from the reaction of H2A-glu with Co（CH3COO）2·4H2O or Cd（CH3COO）2·2H2O in the presence of Im. Both of the complexes display different coordination environment and similar one-dimensional chain structure. The magnetic susceptibility measurements for 1 show a weak antiferromagnetic interaction between two cobalt（Ⅱ） ions bridged by A-glu ligand. The complex 2 exhibits an intense fluorescent emission in solid state at room temperature.     

SPME-GC-MS分析瀑布毛峰茶叶的赋香成分

采用顶空-固相微萃取法(SPME)从瀑布毛峰茶叶中提取挥发性成分,用气相色谱-质谱法(GC-MS)分析其组成。从一级和特级茶叶中分别鉴定了相对含量大于0.50%的化合物48个和41个,其中共同组分27个。一级瀑布毛峰茶叶的主要挥发性成分有壬醛(9.22%),芳樟醇(4.75%),牛儿醇(4.07%),(Z)-3-己烯-1-醇(3.53%),十一醛(3.16%),邻苯二甲酸二异丁酯(2.94%),十六烷(2.35%),己醛(2.00%),1-辛醇(1.97%),6-甲基-5-庚烯-2-酮(1.86%)。特级瀑布毛峰茶叶的主要挥发性成分有:壬醛(8.85%),1-辛烯-3-醇(6.37%),十一醛(4.81%),2,5,5-三甲基-1-己烯(2.84%),辛醛(2.73%),1-辛醇(2.63%),6-甲基-5-庚烯-2-酮(2.60%),芳樟醇(2.20%),1-戊醇(2.20%),己醛(2.16%)。两个等级的瀑布毛峰茶的主要挥发性成分大致相同,但各成分的含量存在一定差异。     

Modulation of localized solutions for the Schrödinger equation with logarithm nonlinearity

We investigate the presence of localized analytical solutions of the Schrödinger equation with logarithm nonlinearity. After including inhomogeneities in the linear and nonlinear coefficients, we use similarity transformation to convert the nonautonomous nonlinear equation into an autonomous one, which we solve analytically. In particular, we study stability of the analytical solutions numerically.     

Numerical solutions of boundary value problems for variable coefficient generalized KdV equations using Lie symmetries

The exhaustive group classification of a class of variable coefficient generalized KdV equations is presented, which completes and enhances results existing in the literature. Lie symmetries are used for solving an initial and boundary value problem for certain subclasses of the above class. Namely, the found Lie symmetries are applied in order to reduce the initial and boundary value problem for the generalized KdV equations (which are PDEs) to an initial value problem for nonlinear third-order ODEs. The latter problem is solved numerically using the finite difference method. Numerical solutions are computed and the vast parameter space is studied.     

Analysis of diffusion process in fractured reservoirs using fractional derivative approach

The fractal geometry is used to model of a naturally fractured reservoir and the concept of fractional derivative is applied to the diffusion equation to incorporate the history of fluid flow in naturally fractured reservoirs. The resulting fractally fractional diffusion (FFD) equation is solved analytically in the Laplace space for three outer boundary conditions. The analytical solutions are used to analyze the response of a naturally fractured reservoir considering the anomalous behavior of oil production. Several synthetic examples are provided to illustrate the methodology proposed in this work and to explain the diffusion process in fractally fractured systems.     

Region-based object and background extraction via active contours

In this paper, we propose a region-based model for the object and background extraction with application to the image with thick or complex boundary. Based on region information of the image, we employ two curves to extract the object and background, respectively, regardless of the boundary. The first curve is used to extract the object. Correspondingly, the second curve is used to extract the background. By employing two level set functions to represent the two curves, we propose a new region-based energy functional. In the proposed model, a distance constraint term is incorporated, which effectively avoid that the two level set functions too away from each other and keep their similar shapes well. Besides, we present a penalty term to maintain the accurate computation and stability evolution. Experiment results demonstrate the desirable performance of the proposed model with application to synthetic and real-world images.     

Co3V2O8/石墨烯复合负极材料的合成及其储锂性能

以石墨烯为基底,CoCl2·2H2O和NH4VO3为原料,采用水热结合热处理方法合成了Co3V2O8/石墨烯复合电极材料;采用XRD、Raman、XPS、SEM、(HR-)TEM和恒电流充放电等对材料进行了结构表征与电化学性能测试。结果表明:Co3V2O8/rGO复合材料表现出优异的放电比容量、优秀的倍率性能和稳定的循环性能(当电流密度为200 mA·g^-1,经过100次循环后,可逆放电比容量为1208 mAh·g^-1);Co3V2O8/rGO电极材料表现出优异的倍率和循环性能可以归因于:独特的石墨烯包覆结构可以有效地提高材料的导电性和增强结构的稳定性、缓解Co3V2O8粒子在循环过程中的聚结和膨胀现象;此外,Co3V2O8纳米颗粒均匀地嵌在石墨烯层间防止了石墨烯片层间的堆叠。     

Synthesis and crystal structures of the Zn(II) and Co(II) complexes containing the reduced derivative nitronyl nitroxide

Two complexes of formulas [Zn(Hfac)₂(IM-IMH-Bph)] (I) and [Co(Hfac)₃](IM-Bph) (II), where IM-Bph = 2,2′-bis(1′-oxyl-4′,4′,5′,5′-tetramethylimidazoline-2′-yl)-bis(2-formylphenyl) ether; Hfac = hexafluoroacetylacetonate, have been synthesized and characterized by single-crystal X-ray diffraction. The X-ray analysis demonstrates that both I and II are mononuclear complexes. In I, each zinc ion is five-coordinated with four oxygen atoms from two Hfac ligands and one oxygen atom from nitroxide. Complex II contains one Co(III) atom with six oxygen atoms from three Hfac ligands and uncoordinated IM-Bph diradical, in which the Co²⁺ ion and NIT-Bph biradical can undergo the redox reaction.