On the Crystal Structure of [Cu(OH)_2(H_2O)_2(4-C_5H_4NCOOH)_2]

In their report of the crystal structure of the compound claimed to be [Cu(OH)2(H2O)2(4- C5H4NCOOH)2], the authors did not give any experimental details on the location and refinement of the water and hydroxyl hydrogen atoms[1]; they had assumed the presence of the carboxylic -CO2H unit on the basis of the infrared stretching frequency at 1700 cm-1 that is only of medium intensity. The cell constants for the compound are, in fact, identical, with those documented for tetraaquabis(isonicot…     

Dirac current in expanding spacetime

We study the behaviour of Dirac current in expanding spacetime with Schrödinger and de Sitter form for the evolution of the scale-factor. The study is made to understand the particle-antiparticle rotation and the evolution of quantum vacuum leading to particle production in such spacetime.     

热解压力对生物质焦结构及气化反应性能的影响

利用加压固定床反应器、吸附仪、X射线衍射仪、元素分析仪、电感耦合等离子原子发射光谱仪等考察了热解压力对生物质半焦(以下简称半焦)产率、物化结构、元素组成的影响规律。同时,利用热天平对不同热解压力下所制半焦的气化行为进行了考察。结果表明,随热解压力升高,半焦产率增大,当压力升至1.0 MPa后,半焦产率基本不变;半焦中C元素含量随热解压力的升高而增加,而H元素含量和BET比表面积则减小;此外,随热解压力升高,玉米秸秆焦和锯末焦的石墨化程度增强,而稻壳焦的石墨化程度则基本不受热解压力影响。气化反应的研究表明,玉米秸秆焦及锯末焦的平均气化反应速率随热解压力的提高而减小,而稻壳焦的平均气化反应速率基本不受热解压力的影响。热解压力对半焦BET比表面积及碳微晶结构的影响规律与气化反应速率变化规律的对比研究表明,热解压力引起半焦微晶结构的变化是造成热解压力对半焦气化反应速率影响的主要原因。     

基于6-羟基-2-吡啶基膦酸配体的铜配合物的合成、结构及磁性

在水热条件下, 以6-羟基-2-吡啶基膦酸为主配体, 4, 4′-联吡啶(bpy)及1, 2-二(4-吡啶基)乙烯(bpe)为桥联配体, 合成了2个铜膦酸配位聚合物[Cu₃(L)₂(bpy)₂(H₂O)₂]· 2H₂O (1), [Cu₃(L)₂(bpy)₂(H₂O)₃]· 2H₂O (2)。配合物1中, Cu²⁺离子由膦酸配体连接成一条链, 该链由bpy桥联成二维层, 层与层之间通过氢键作用构成三维结构。配合物2与配合物1是同构的, 桥联配体是bpe。磁性研究表明, 配合物1与2中铜离子之间存在反铁磁性耦合。     

Solving sparse non-negative tensor equations: algorithms and applications

We study iterative methods for solving a set of sparse non-negative tensor equations (multivariate polynomial systems) arising from data mining applications such as information retrieval by query search and community discovery in multi-dimensional networks. By making use of sparse and non-negative tensor structure, we develop Jacobi and Gauss-Seidel methods for solving tensor equations. The multiplication of tensors with vectors are required at each iteration of these iterative methods, the cost per iteration depends on the number of non-zeros in the sparse tensors. We show linear convergence of the Jacobi and Gauss-Seidel methods under suitable conditions, and therefore, the set of sparse non-negative tensor equations can be solved very efficiently. Experimental results on information retrieval by query search and community discovery in multi-dimensional networks are presented to illustrate the application of tensor equations and the effectiveness of the proposed methods.     

C~*-代数的Murray-von Neumann分类理论的抽象架构

Murray和von Neumann在对W~*-代数进行分类工作时,主要的工具是刻画W~*-代数中的投影的性质(事实上,W~*-代数是由投影所生成的).因为一般的C~*-代数可能不包含任何非零的投影,所以不能将Murray和von Neumann的方法,直接地应用到C~*-代数上来得出分类理论.本文作者在最近的两项工作中,分别使用C~*-代数的开投影和正元来代替投影,得到两套平行的Murray-von Neumann式的分类理论.本文在简单描述了这两套分类理论之后,将会给出一个一般的分类架构,它可以用来得出好些C~*-代数的分类理论(包括我们之前的两套理论),我们也会通过它来讨论各种分类理论之间的等价性,并给出之前两套理论的细化.     

Parameter Estimation for Observed Diffusions in Manifolds

Following the procedure described by Elworthy (1982) and Ikeda& Watanabe (1981) we construct the solution of stochasticdifferential equations (SDEs) in manifolds. We take such SDEsto describe parametrized completely observed stochastic systemsand manifold-valued state processes. The likelihood functionfor the system parameter is computed by two methods: the firstapplies to the case of parallelizable manifolds; the secondapplies to the general case, here the solution of the systemSDE is constructed in the orthonormal frame bundle of the manifold.Two examples are given.     

Crystal Structure of catena-[（Tetrakis-μ2-acetato-μ2-4,4＇-bipyridine） dicopper（Ⅱ）] Acetonitrile Solvate

1 INTRODUCTION Much attention has been paid to 1D, 2D and 3D coordination polymers because they can meet the need of functional materials with desired structures and properties[1～5]. One strategy in the design and synthesis of coordination architectures is the buil- ding-block approach. Commonly, bi- or multidentate organic ligands containing N[6, 7] or O[8, 9] atoms have ever been used in the construction. In our cur- rent work, we have selected melamine ligand as the main building bl…     

Space Group of Aquaimidazolemaleatozinc, [(H2O)(C3H4N2)(O2CCH=CHCO2Zn)]n

The space group of [(H2O)(C3H4N2)(O2CCH=CHCO2Zn)]n, which was originally described in the acentric Pc space group (Liu et al., Chin. J. Struct. Chem. 2004, 23, 160～163), is re-described in the centric P21/c space group.The crystal structure of (H2O)(C3H4N2)O2C-CH=CHCO2Zn was refined in the acentric Pc space group on 266 variables to R = 0.037 for the 1926 of the 2067 obeying the I > 2σ criterion[1]. The structure is better described in the centric P21/c space group (Table 1) as the two indepen-dent formula units are related by a center of symmetry. The 21 screw axis is must be pre-sent, as noted from the systematically absent 0k0 (k = 2n + 1) reflections in the 3302 reflections that were simulated[2, 3] from the published cell dimensions and atomic coordinates. Crystallo-graphica[4] estimates the hemisphere of reflections to be 3302, so that only a little more than the minimum monoclinic data must have been collec-ted in the study. A revision from Pc to P21/c is not particularly common[5] as the P21/c space group is uniquely determined from systematic absences. The polymeric chain propagates linearly along the c-axis of the unit cell (Fig. 1).     

ZnTPP Axially Coordinated with a Novel Dipyridylamine Ligand: Hydrothermal Synthesis and Crystal Structure

A novel complex ZnTPPL1·3DMF 1(TPP = tetraphenylporphyrin,L1 = N-(4-(9-carbazolyl) phenyl)-N,N-di(4-pyridyl)amine) was prepared by a hydrothermal method and characterized by elemental analysis,IR,and single-crystal X-ray diffraction analysis.Compound 1 crystallizes in triclinic,space group P1 with a = 13.3082(2),b = 14.3276(2),c = 18.6120(3) ,α = 109.853(1),β = 95.054(1),γ = 98.832(1)°,V = 3260.57(9) 3,Z = 2,Dc = 1.334 g/cm3,C81H69N11O3Zn,Mr = 1309.84,μ(MoKα) = 0.438 mm-1,F(000) = 1372,GOF = 1.159,the final R = 0.0482 and wR = 0.1479 for 12091 observed reflections(Ⅰ 2σ(Ⅰ)).Crystal structure analyses revealed that L1 utilizes one pyridyl N atom to bind Zn via axial coordination,affording a 1:1 complex.The binding constant was estimated to be 1.74(7) × 104 M-1 from electronic spectra measurements.