火花直读光谱法对铝合金中各元素含量测量结果的不确定度评定

分析了火花直读光谱法测定铝合金中Si、Fe、Cu、Mg、Mn、Zn、Cr、Ti元素含量测量结果的不确定度来源,对不确定度分量进行了评定与计算,Si、Fe、Cu、Mg、Mn、Zn、Cr、Ti测量结果的相对扩展不确定度分别为2. 9%、2. 5%、2. 6%、2. 7%、2. 6%、2. 6%、2. 5%、2. 7%(包含因子k均为2).     

Synthesis, crystal and band structures, and optical properties of a new supramolecular complex: [Hg6Sb4](InBr6)Br

A new supramolecular complex [Hg₆Sb₄](InBr₆)Br (1) has been prepared by the solid-state reaction of HgBr₂ with elemental In and Sb at 450 °C. The crystal structure of 1 features a three-dimensional [Hg₆Sb₄]⁴⁺ framework with cavities of two different sizes occupied by different kinds of guest anions. The bigger cavities are filled with the octahedral InBr₆³⁻ ions, while the smaller cavities trap Br⁻ ions. The optical properties were investigated in terms of the diffuse reflectance and infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is semiconductor, and the optical absorption is mainly originated from the charge transitions from Sb-5p and Br-4p to In-5s and Hg-6s states.     

Solution‐Based Evolution and Enhanced Methanol Oxidation Activity of Monodisperse Platinum–Copper Nanocubes

Shape‐controlled catalysis : High‐quality Pt–Cu nanocubes with an average size of about 8 nm (see picture, scale bar=20 nm) were synthesized from a high‐temperature organic solution system in the presence of various capping ligands. These cubic Pt–Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt–Cu and Pt nanospheres.

     

A Bahri–Lions theorem revisited

In 1988, A. Bahri and P.L. Lions [A. Bahri, P.L. Lions, Morse-index of some min–max critical points. I. Application to multiplicity results, Comm. Pure Appl. Math. 41 (1988) 1027–1037] studied the following elliptic problem:

where Ω is a bounded smooth domain of , 2<p<(2N−2)/(N−2) and f(x,u) is not assumed to be odd in u. They proved the existence of infinitely many solutions under an appropriate growth restriction on f. In the present paper, we improve this result by showing that under the same growth assumption on f the problem admits in fact infinitely many sign-changing solutions. In addition we derive an estimate on the number of their nodal domains. We also deal with the corresponding fourth order equation Δ²u=|u|^p−2u+f(x,u) with both Dirichlet and Navier boundary conditions, as well as with strongly coupled elliptic systems.     

Corrigendum to: “Oscillation criteria for first-order impulsive differential equations with positive and negative coefficients” [J. Comput. Appl. Math. 217 (1) (2008) 28–37]

This communication gives the corrigendum to the paper “Oscillation criteria for first-order impulsive differential equations with positive and negative coefficients” (JCAM (2007), doi:10.1016/j.cam.2007.06.016).     

Analysis of linear and quadratic simplicial finite volume methods for elliptic equations

This paper is devoted to analysis of some convergent properties of both linear and quadratic simplicial finite volume methods (FVMs) for elliptic equations. For linear FVM on domains in any dimensions, the inf-sup condition is established in a simple fashion. It is also proved that the solution of a linear FVM is super-close to that of a relevant finite element method (FEM). As a result, some a posterior error estimates and also algebraic solvers for FEM are extended to FVM. For quadratic FVM on domains in two dimensions, the inf-sup condition is established under some weak condition on the grid.     

粉末注射成形坯孔隙度的分形模型

粉末注射成形坯是一种具有分形特性的典型的多孔介质,借助于多孔介质孔隙结构的分形理论,对粉末注射成形坯孔隙率的分形模型进行推导。首先分析了粉末注射成形坯孔隙结构的双重分形特性,介绍了粉末注射成形坯孔隙分布分形维数和孔隙迂曲分形维数,然后推导出粉末注射成形坯孔隙度的分形模型。     

Design of open-framework germanates by combining different building units

Open-framework germanates with extra-large channels are built from two different types of clusters. The two different clusters are connected in such a way to form a pseudo-body-centered cluster aggregate (PBCCA). The different packing of PBCCAs resulted in different 3D open-framework germanates.     

Gold(I) eta2-arene complexes

The reaction of 9-{[N-n-propyl-N-(diphenylphosphino)amino]methyl}anthracene (1) with Au(SMe2)Cl yields complex 2 with an arm-opening configuration. The latter is treated with AgClO4 to form complex 4 and then respectively reacted with acetonitrile, pyridine, and triphenylphosphine sulfide to afford novel gold(I) eta2-arene complexes 3a-c, which have arm-closing configurations and feeble or weak fluorescence emissions. The observation can be attributed to charge transfer from the anthracene unit to the Au+ ion. When the solution of 3a or 4 in CH2Cl2 was added with 1 equiv of Ph3P, complex 5 with the arm-opening configuration was formed and strong emission was restored.     

Sugar-assisted kinetic resolution of amino acids and amplification of enantiomeric excess of organic molecules

The origins of biological homochirality have intrigued researchers since Pasteur's discovery of the optical activity of biomolecules. Herein, we propose and demonstrate a novel alternative for the evolution of homochirality that is not based on autocatalysis and forges a direct relationship between the chirality of sugars and amino acids. This process provides a mechanism in which a racemic mixture of an amino acid can catalyze the formation of an optically active organic molecule in the presence of a sugar product of low enantiomeric excess.