The origin of the high performance of tungsten carbides/carbon nanotubes supported Pt catalysts for methanol electrooxidation

The Pt supported on WC modified MWCNT catalysts (PtWC/MWCNT) were synthesized by the combination of organic colloidal and intermittent microwave heating (IMH) methods for the first. The results proved the better performance of the PtWC/MWCNT catalyst than that of Pt/C for methanol oxidation in terms of the onset potential and peak current density. The synergistic effect between Pt nanoparticles and WC and the structure effect of the MWCNTs could be the reasons to result in the high activity. The CO stripping test provided the evidence that the onset potential shift for methanol oxidation is consistent with the reduction in the overpotential for the CO oxidation on PtWC/MWCNT catalyst. Therefore, the mechanism of the high performance for methanol oxidation on PtWC/MWCNT catalyst is probably the easier oxidation of CO-like species which cause high overpotential for further oxidation of methanol.     

ON MULTILINEAR COMMUTATORS OF Θ-TYPE CALDERóN-ZYGMUND OPERATORS

In this paper, we discuss the multilinear commutator of θ-type Calderón- Zygmund operators, and obtain that this kind of multilinear commutators is bounded from Lp(Rn) to Lq(Rn), from Lp(Rn) to Triebel-Lizorkin spaces and on certain Hardy type spaces.     

Pointwise characterization for combinations of Szász-Mirakjan operators

The purpose of this paper is to characterize the pointwise rate of convergence for the combinations of Szász-Mirakjan operators using Ditzian-Totik modulus of smoothness.     

用多孔玻璃膜管悬浮聚合法制备单分散性聚苯乙烯微球

Monodisperse polystyrene microspheres are prepared by shell porous glass(SPG)-suspension polymerization. The influences of SPG on size and size dispersity of the microspheres are investigated. The properties of the microspheres are studied by GPC, TEM and SEM. The results indicate that the polystyrene microspheres possess definite monodispersibity and their particle size is in the range of 5～12μm.     

Structural and electrochemical behavior of Mn–V oxide synthesized by a novel precipitation method

Manganese–vanadium oxide had been synthesized by a novel simple precipitation technique. Scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, thermogravimetric analysis/differential scanning calorimetry, and X-ray photoelectron spectroscopy were used to characterize Mn–V binary oxide and δ-MnO₂. Electrochemical capacitive behavior of the synthesized Mn–V binary oxide and δ-MnO₂ was investigated by cyclic voltammetry, galvanostic charge–discharge curve, and electrochemical impedance spectroscope methods. The results showed that, by introducing V into δ-MnO₂, the specific surface area of the mixed oxide increased due to a formation of small grain size. The specific capacitance increased from 166 F g⁻¹ estimated for MnO₂ to 251 F g⁻¹ for Mn–V binary oxide, and the applied potential window extended to −0.2–1.0 V (vs. saturated calomel electrode). Through analysis, it is suggested that the capacitance performance of Mn–V binary oxide materials may be improved by changing the following three factors: (1) small grain and particle size and large activity surface area, (2) appropriate amount of lattice water, and (3) chemical state on the surface of MnO₂ material.     

Convenient preparation of N-8-quinolinyl benzenesultams as novel NF-κB inhibitors

An efficient synthesis of a series of N-8-quinolinyl benzenesultams as novel NF-κB inhibitors was described via diazotization-induced cyclization of easily accessible N-8-quinolinyl-2-aminobenzenesulfonamides.     

Detection of the photochemical intermediate processes in phycobiliproteins

The delayed luminescence was applied to detect the intermediate processes of the excitedstate decay in the selectively excited phycobiliproteins. Phosphorescence spectra of the five types of phycobiliproteins, R-PE, CPC, APC, R-PC, PEC were reported in this article. The five phycobiliproteins showed different phosphorescence yields, the sequence of which was the same as that of the singlet oxygen yields. Based on the observation, it can be concluded that each of the chromophores possesses a characteristic phosphorescence emission. The delayed luminescence spectra of APC at different aggregation states (trimer, monomer and denatured APC) are researched. The lower aggregation APC showed less phosphorescence because of relative loose structures and less interaction with the surrounding proteins, while the denatured APC showed delayed fluorescence instead of phosphorescence because of triplet-triplet annihilation.     

Evolutionary structural optimisation using an additive algorithm

The evolutionary structural optimisation (ESO) method has been under continuous development since 1992. Traditionally, the method was conceived from the engineering perspective that the topology and shape of structures were naturally conservative for safety reasons and therefore contained an excess of material. To move from the conservative design to a more optimum design would therefore involve the removal of material. Thus the ESO method started from a design space much bigger than the optimum and the final topology or shape emerged by a process of removal of unwanted/inefficient/lowly stresses material. The original algorithms allowed for two forms of evolution. One was there the understressed material could be removed from anywhere in the allowable design space, and with compensation for checker-boarding this produces an optimum topology under the prescribed environments. The second form only allows removal from the surface or parts of the surface (called nibbling in the ESO lexicon); this produces a Min–Max situation where the maximum surface stress is reduced to a minimum. It has been demonstrated that the ESO process produces a surface that is an iso-stress contour thus satisfying the Min–Max optimality criterion. The present paper addresses the opposite evolutionary process whereby the structure evolves from a base which is the minimum structural form required to carry the load regardless of the magnitude of the stress levels. Material is added in the proximity of high stress to ameliorate its effect and hence the final structural form emerges. Only singly connected regions are formed in the present analysis and thus the additive ESO process is the opposite of the nibbling SO, mentioned above, that produces optimum surface shapes. The paper presents a brief background to the current state of structural optimisation research. This is followed by a discussion of the strategies for the additive ESO (AESO) algorithm and two examples are presented.     

对称广义中心对称矩阵模型修正的矩阵逼近法及其扰动性

X,B是实测的位移矩阵和载荷矩阵,C是有限元方法得到的估计矩阵,给出了AX=B的对称广义中心对称矩阵解集合ζ的表达式,对于逼近问题||C-A||F=min A∈ζ||C-A||F的解A,给出了它的表达式并分析了解A的扰动性,数值结果表明方法是行之有效的.