Influences of Hydration Force and Elastic Strain Energy on the Stability of Solid Film in a Very Thin Solid-on-Liquid Structure

Since hydration forces become very strong at short range and are particularly important for determining the magnitude of the adhesion between two surfaces or interaction energy, the influences of the hydration force and elastic strain energy due to hydration-induced layering of liquid molecules close to a solid film surface on the stability of a solid film in a solid-on-liquid (SOL) nanostructure are studied in this paper. The liquid of this thin SOL structure is a kind of water solution. Since the surface forces play an important role in the structure, the total free energy change of SOL structures consists of the changes in the bulk elastic energy within the solid film, the surface energy at the solid-liquid interface and the solid-air interface, and highly nonlinear volumetric component associated with interfacial forces. The critical wavelength of one-dimensional undulation, the critical thickness of the solid film, and the critical thickness of the liquid layer are studied, and the stability regions of the solid film have been determined. Emphasis is placed on calculation of critical values, which are the basis of analyzing the stability of the very thin solid film.

On the formation of well-aligned ZnO nanowall networks by catalyst-free thermal evaporation method

Two-dimensional ZnO nanowall networks were grown on ZnO-coated silicon by thermal evaporation at low temperature without catalysts or additives. All of the results from scanning electronic spectroscope, X-ray diffraction and Raman scattering confirmed that the ZnO nanowalls were vertically aligned and c-axis oriented. The room-temperature photoluminescence spectra showed a dominated UV peak at 378 nm, and a much suppressed orange emission centered at similar to 590 nm. This demonstrates fairly good crystal quality and optical properties of the product. A possible three-step, zinc vapor-controlled process was proposed to explain the growth of well-aligned ZnO nanowall networks. The pre-coated ZnO template layer plays a key role during the synthesis process, which guides the growth direction of the synthesized products. (C) 2007 Elsevier B.V. All rights reserved.

闭合水平环状日珥的磁流体静力学平衡

对太阳进行的H_α单色光观测有时会看到水平环状日珥。本文着重讨论了这种等离子体环的静力学平衡。对于这种轴对称和闭场条件的情形,求得磁场和密度的解析解。本文的结论表明,在不同的重力场和线性无力因子α的影响下,磁面形状和热力学参量的分布会有很大的变化。

高频感应等离子体动力学及其应用

<正> 高频感应等离子体技术是近十多年发展起来的一门新技术,由于它具有无电极污染,弧区大,温度均匀,能提供纯净热源,工质不受限制等特点,在化工、冶金等工业和各个科学技术领域中有着潜在的应用前景.因为过去对能够稳定并控制热等离子体流的某些方法和装置,以及对高频放电理论,等离子体动力学进行了卓有成效的研究,所以促使这个新方向得

在强激光下Ge平行板的动态F-P干涉效应

实验表明,在连续CO_2激光辐照下,Ge平行板透射光强度随时间呈准周期性的变化。基于平行平面板的多光束干涉理论,并考虑激光引起的温升对Ge片折射率和厚度的影响,得到的计算结果与实验相符合。这说明平行平面Ge在高功率连续CO_2激光作用下因折射率和厚度随温度的变化而具有一种动态的法布里-珀罗干涉效应。

广义WKB方法及其对浅水波问题的应用

本文首先指出WKB方法可适用于更广泛的一类方程,并把它应用于线性化浅水波方程。对浅水波焦散区的非线性情形,用广义WKB方法进行了讨论,把文献[4]的结果推广到一般弯曲焦散线的情形。

An asymptotic analysis for one dimensional stress wave propagation in damaged viscoelastic media

A regular perturbation technique is suggested to deal with the problem of one dimensional stress wave propagation in viscoelastic media with damage. Based upon the first order asymptotic solution obtained, the characteristics of wave attenuation are studied. In fact, there exist three different time-dependent phenomena featuring the dynamic response of the materials, the first expressing the characteristics of wave propagation, the second indicating the innate effect of visco-elastic matrix and the third coming from the time dependent damage. The comparision of first order asymptotic solution with the numerical results calculated by a finite difference procedure shows that the perturbation expansion technique may offer a useful approach to the problem concerned.

弱粘性流体中垂直激励表面波的阻尼效应

在竖直振动的圆柱形容器中，将Navier-Stokes方程线性化，利用两时间尺度奇异摄动展开法研究了弱粘性流体的单一自由面驻波运动．整个流场被分为外部势流区和内部边界层区两部分，对两部分区域分别求解，得到包含阻尼项和外驱动影响的线性振幅方程．利用稳定性分析，得到形成稳定表面波的条件，给出了临界曲线．此外，还获得了阻尼系数的解析表达式．最后，将线性阻尼加到理想流体条件下所得到的色散关系中对其进行修正，理论结果证明修正后的驱动频率更加接近实验的结果．通过计算发现，当驱动的频率较低时，流体的粘性对表面波模式选择有重要影响，而表面张力的影响不明显；但当驱动频率较高时，流体的表面张力起主要作用，而流体的粘性影响甚小．

微孔泡沫塑料力学行为的研究综述

对微孔泡沫塑料力学行为的研究文献进行了综述，简单介绍了微孔泡沫塑料的制备和表征方法，重点介绍了微孔泡沫塑料力学性能的研究工作，其中也包括作者近期在该领域的一些工作。这些工作主要讨论了微孔泡沫塑料的压缩、拉伸、冲击、疲劳和黏弹性效应。最后，给出了对该领域工作的一些讨论和展望。

Neutron source from thin foil confined by two laser pulses

Neutron production from a thin deuterium-tritium (D-T) foil irradiated by two intense femtosecond laser pulses from opposite sides with zero phase difference is studied analytically and numerically. For the interaction of a laser pulse of amplitude a = 7, focal area 100 mu m(2) and areal density 4.4 x 10(18) cm(-2) with a D-T plasma foil, about 1.17 x 10(21) neutron s(-1) can be obtained, much more than from other methods. The profiles of the ion and electron densities are also calculated.

Analysis on fluorescence intensity reverse photonic phenomenon between red and green fluorescence of oxyfluoride nanophase vitroceramics

An interesting fluorescence intensity reverse photonic phenomenon between red and green fluorescence is investigated. The dynamic range. of intensity reverse between red and green fluorescence of Er( 0.5) Yb( 3): FOV oxyfluoride nanophase vitroceramics, when excited by 378.5nm and 522.5nm light respectively, is about 4.32 x 10(2). It is calculated that the phonon- assistant energy transfer rate of the electric multi- dipole interaction of {(4)G(11/2)( Er3+) -> F-4(9/2)( Er3+), F-2(7/2)( Yb3+). F-2(5/2)( Yb3+)} energy transfer of Er( 0.5) Yb( 3): FOV is around 1.380 x 10(8) s(-1), which is much larger than the relative multiphonon nonradiative relaxation rates 3.20 x 10(5) s(-1). That energy transfer rate for general material with same rare earth ion's concentration is about 1.194 x 10(5) s(-1). These are the reason to emerge the unusual intensity reverse phenomenon in Er( 0.5) Yb( 3): FOV. (C) 2007 Optical Society of America.

Effects of chloride substitution on the chemical and physical properties and the crystallization behavior in heavy metal fluoride glasses

Effect of the substitutions of chloride for fluoride on the chemical and physical properties and the crystallization behavior in heavy metal fluoride glasses has been investigated. The characteristic temperature of the glass does not changed obviously when the fluoride was taken place by chloride. Compared with samples of being free of ErF3, the doping samples are more inclined to be surface crystallization. Optical basicity in the glass system increases with increasing the negative charge provided by the chloride atoms and the absorption peak red shifted is observed in absorption spectra. XRD measurements show that not a single crystalline phase appears in the heated glass samples, which indicate the substitutions of chloride for fluoride with a variety of crystalline precipitation trends. (c) 2007 Elsevier B.V All rights reserved.