Raman characterizations and structural properties of the binary TeO2?WO3, TeO2?CdF2 and ternary TeO2?CdF2?WO3 glasses

The Raman spectroscopy technique was used to characterize the microstructure and the crystallization properties of the as‐cast and heat‐treated binary TeO₂ WO₃, TeO₂ CdF₂ and ternary TeO₂ CdF₂ WO₃ glasses and glass ceramics. The results were compared with those obtained by using the X‐ray diffraction technique. The effect of the WO₃ and CdF₂ contents on the TeO₂ glass network and the intensity ratios of the deconvoluted Raman peaks were determined. The shifts in the Raman band wavenumbers and the intensity values for each band were investigated. The Raman results indicated that the glasses were mainly formed by the [TeO₄] and [TeO₃] units. The [TeO₄] units convert to [TeO₃] units with the addition of WO₃ and CdF₂ into tellurite glasses. All the crystalline phases such as α‐TeO₂, δ‐TeO₂ and γ‐TeO₂ existing in the TeO₂ WO₃, TeO₂ CdF₂ and TeO₂‐ WO₃ CdF₂ glasses were determined. The transformation of the metastable γ‐TeO₂ phase into stable α‐TeO₂ was observed for the (1 − x)TeO₂ xWO₃ (where x = 0.15, 0.20, 0.25), 0.90Te₂ 0.10CdF₂, the 0.85TeO₂ 0.10CdF₂ 0.05WO₃ and 0.80TeO₂ 0.10CdF₂ 0.10WO₃ glasses, and the transformation of the metastable δ‐TeO₂ phase into the stable α‐TeO₂ was also observed for the TeO₂ CdF₂ WO₃ glass system. In addition, an unidentified phase formation, labeled ε, was determined. Copyright © 2009 John Wiley & Sons, Ltd.     

经济研究中的物理学

当前的金融危机再次表明,传统经济学作为一门学科缺乏解释力和预测力.造成这个令人失望的状况的根本原因是由于经济学家没有按照科学的范式来发展这个学科.经济学的现状吸引了一群物理学家进入这个学科并形成了一个新的交叉学科——经济物理学,人们期望它在促进经济学科学化的进程中起决定性作用.文章首先简要介绍了经济学的主要内容,说明经济学理论是建立在理性和均衡假定基础之上的;接着论述了为什么经济学还不是一门科学,指出经济学研究不是基于逻辑实证主义原则来开展的;文章还分析了物理学家是如何研究经济问题的,介绍了经济物理学的主要研究内容和研究方法;文章最后提出经济学范式的转变必须从观察和实验出发,经济学理论必须建立在一个合理设计的量纲体系和对实际经济运行过程的正确理解基础之上.     

Temperature-dependent vortex matter in a superconducting mesoscopic circular sector

Nonlinear time-dependent Ginzburg–Landau (TDGL) equations were solved in the present work using the link variables method. Vortex configurations were investigated in a superconducting circular sector immersed in an external magnetic field applied perpendicular to its plane. Magnetization and free energy were calculated as a function of the applied magnetic field at several temperatures. This paper illustrates how the vortices moved around at the transition fields before they become accommodated into an equilibrium configuration. A linear dependence of the magnetization dependence on temperature has been found for a certain magnetic field.     

Efficient one-pot synthesis of Ag nanoparticles loaded on N-doped multiphase TiO2 hollow nanorod arrays with enhanced photocatalytic activity

The simultaneous Ag loaded and N-doped TiO₂ hollow nanorod arrays with various contents of silver (Ag/N-THNAs) were successfully synthesized on glass substrates by one-pot liquid phase deposition (LPD) method using ZnO nanorod arrays as template. The catalysts were characterized by Raman spectrum, field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), ultraviolet-vis (UV-vis) absorption spectrum and X-ray photoelectron spectroscopy (XPS). The results suggest that AgNO₃ additive in the precursor solutions not only can promote the anatase-to-rutile phase transition, but also influence the amount of N doping in the samples. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The sample exhibited the highest photocatalytic activity under UV light illumination when the AgNO₃ concentration in the precursor solution was 0.03 M, due to Ag nanoparticles acting as electron sinks; When the AgNO₃ concentration was 0.07 M, the sample performed best under visible light illumination, attributed to the synergetic effects of Ag loading, N doping, and the multiphase structure (anatase/rutile).     

An investigation of structural phase transformation and electrical resistivity in Ta films

In this work, we report the effect of substrate, film thickness and sputter pressure on the phase transformation and electrical resistivity in tantalum (Ta) films. The films were grown on Si(1 0 0) substrates with native oxides in place and glass substrates by varying the film thickness (t) and pressure of the working gas (p_Ar). X-ray diffraction (XRD) analysis showed that the formation of α and β phases in Ta films strongly depend on the choice of substrate, film thickness t and sputter pressure p_Ar. A stable α-phase was observed on Si(1 0 0) substrates for t ≤ 200 nm. Both α and β phases were found to grow on glass substrates at all thicknesses except t = 100 nm. All the films grown on Si(1 0 0) substrates for p_Ar ≤ 6.5 mTorr had α-phase with strong (1 1 0) texture normal to the film plane. The glass substrates promoted the formation of β-phase in all p_Ar except p_Ar = 5.5 mTorr. The resistivity ρ was observed to decrease with t, whereas ρ was increased with p_Ar on Si(1 0 0) substrates. In all films, the measured resistivity ρ was greater than the bulk resistivity. The resistivity ρ was influenced by the effects of surface roughness and grain size.     

Characterization of Triebel–Lizorkin type spaces with variable exponents via maximal functions,local means and non‐smooth atomic decompositions

In this paper we study the maximal function and local means characterizations and the non‐smooth atomic decomposition of the Triebel–Lizorkin type spaces with variable exponents . These spaces were recently introduced by Yang et al. and cover the Triebel–Lizorkin spaces with variable exponents as well as the classical Triebel–Lizorkin spaces , even the case when . Moreover, covered by this scale are also the Triebel–Lizorkin‐type spaces with constant exponents which, in turn cover the Triebel–Lizorkin–Morrey spaces. As an application we obtain a pointwise multiplier assertion for those spaces.     

Study on a kind of $p$-Laplacian neutral differential equation with multiple variable coefficients

In this paper, we first discuss some properties of the neutral operator with multiple variable coefficients $(Ax)(t):=x(t)-\sum\limits_{i=1}^{n}c_i(t)x(t-\delta_i)$. Afterwards, by using an extension of Mawhin''s continuation theorem, a kind of second order $p$-Laplacian neutral differential equation with multiple variable coefficients as follows $$\left(\phi_p\left(x(t)-\sum\limits_{i=1}^{n}c_i(t)x(t-\delta_i)\right)''\right)''=\tilde{f}(t,x(t),x''(t))$$ is studied. Finally, we consider the existence of periodic solutions for two kinds of second-order $p$-Laplacian neutral Rayleigh equations with singularity and without singularity. Some new results on the existence of periodic solutions are obtained. It is worth noting that $c_i$ ($i=1,\cdots,n$) are no longer constants which are different from the corresponding ones of past work.     

Group-invariant solutions, non-group-invariant solutions and conservation laws of Qiao equation

This paper considers a completely integrable nonlinear wave equation which is called Qiao equation. The equation is reduced via Lie symmetry analysis. Two classes of new exact group-invariant solutions are obtained by solving the reduced equations. Specially, a novel technique is proposed for constructing group-invariant solutions and non-group-invariant solutions based on travelling wave solutions. The obtained exact solutions include a set of traveling wave-like solutions with variable amplitude, variable velocity or both. Nonlocal conservation laws of Qiao equation are also obtained with the corresponding infinitesimal generators.     

Blow-up of solutions to a parabolic system with nonlocal source

This paper deals with a parabolic system with different diffusion coefficients and coupled nonlocal sources, subject to homogeneous Dirichlet boundary conditions. The conditions on global existence, simultaneous or non-simultaneous blow-up, blow-up set, uniform blow-up profiles and boundary layer are got using comparison principle and asymptotic analysis methods.