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.     

Preparation of lithium carbonate hollow spheres by spray pyrolysis

Lithium carbonate (Li₂CO₃) hollow spheres were prepared by spray pyrolysis of lithium bicarbonate (LiHCO₃) in this research. The products were characterized by X‐ray diffraction (XRD), scanning electron microscope (SEM), crystal size distribution (CSD) analysis and BET surface area measurement. The XRD figure of the product is nearly the same as the standard pattern, indicating the product achieved by spray pyrolysis has pure Li₂CO₃ crystalline phase. The SEM images show the self‐assembly hollow spheres are composed of about 200 nm primary particles. While the CSD analysis shows the macro‐volume mean crystal size ranges 4‐9 μm depending on the experimental conditions. The BET surface area of the product reaches 7.24 m²/g, which is much higher than the best value reported in the literature. The product prepared in this work has great potential application prospect in the lithium‐battery industry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

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。     

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.     

Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI

The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.     

Surface characterization of poly(methyl methacrylate-co-n-butyl acrylate-co-cyclopentylstyryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography

The surface properties of poly(methyl methacrylate-co-n-butyl acrylate-co-cyclopentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, e.g., specific retention volume, the dispersive component of the surface free energy, the specific interaction contribution to the free energy of adsorption and the acid/base constants were obtained to investigate the interactions between the surfaces of the copolymers and different solvents. It was found that incorporation of styryl-POSS into polymer resulted in increasing interactions between polymers and solvents, dispersive component of surface free energy of polymer and acidity of the surfaces of the polymers. The more the styryl-POSS were embedded, the stronger the interaction between the polymer surface and solvent, the dispersive component of the surface free energy and the acidity of the polymer surface were.