Study of the structural and atomic diffusive properties of the ordered Cu3Au (110) surface

The structural properties, the formation and migration energies of a single vacancy migrating intralayer and interlayer in the CuAu‐terminated (110) surface of Cu₃Au ordered alloy have been calculated and discussed by using the modified analytical embedded‐atom method (MAEAM) and molecular dynamics (MD) methods. The surface layer exhibits rippling that the Au atoms are raised above Cu atoms about 0.117 Å in the topmost layer. The displacements of the topmost two layers are comparatively larger, while the third layer relaxes slightly and there are no changes in the nether layers. From energy minimization, the vacancy is most likely to be formed in the first layer (1L), especially on the Au site. The surface vacancy shows the smallest formation energy compared to the interlayer and bulk vacancies, while the corresponding value converges after the fifth layer (5L). For Cu vacancy originally sited in the second layer (2L) and migrated intralayer and interlayer, the diffusion without causing the local disorder is the most favorable, and the vacancy tends to migrate to the topmost layer. In the topmost layer of the CuAu‐terminated (110) surface, the circularity path is preferred over the beeline path. Copyright © 2011 John Wiley & Sons, Ltd.     

A general radial quasi-interpolation operator on the sphere

Geodetic and meteorological data, collected via satellites for example, are genuinely scattered and not confined to any special set of points. In order to learn geodetic and meteorological rules, one needs to use these scattered data only to construct an approximant or interpolant. In this paper, we introduce a general distance generated from the scattered data, and, using this, construct a general radial quasi-interpolation operator on the sphere, and we study the convergence rate of this operator. We also show some potential applications of the results obtained here in satellite geodesy.     

Double domain wavelength multiplexed Fizeau interferometer with high resolution dynamic sensing and absolute length detection

In this work, we present a simple photonic instrument that has the ability of measuring positions, distances and vibrations with very high resolution by means of two Fizeau interferometers (FI), both using the same optical fiber end as a probe tip itself. On the one hand we have a time domain FI powered with a 1310 nm laser and monitored by an InGaAs detector providing displacement information with resolution around a tenth of nm but regardless of the absolute position of object and of the displacement sense. On the other, a spectral domain FI version based on a super luminescent source (SLED) centred at 800 nm with bandwidth of nearly 40 nm is analysed in real time by means of a digital spectrometer. Each spectrum is acquired in a very small time interval and provides information of both length of the cavity as well as its correct sense of evolution. Resolution of this system is lower than its complementary temporal case, but distance and sense measurements are absolute and can be determined successfully by adequate processing of spectral signal.Both interferometers are optically coupled to a single fiber optic probe and are wavelength modulated.Therefore, combination of both sensors results in a new one which allows the correct knowledge of an object or surfaces under test, i.e. a high resolution of displacement data plus its absolute position and true sense of movement.     

Particle‐Arrayed Silver Mesocubes Synthesized via Reducing Silver Oxide Mesocrystals for Surface‐Enhanced Raman Spectroscopy

In this study, we demonstrate an easy particle‐mediated protocol using the specific structure of mesocrystal Ag₂O sacrificial templates to synthesize highly rough‐cubic Ag mesocages. To the best of our knowledge, the mesocrystal particles are reported for the first time as sacrificial templates for synthesizing metal particles. The obtained Ag mesocages show high surface‐enhanced Raman scattering (SERS) sensitivity because of the highly rough topography formed by arrays of uniform individual Ag nanoparticles. Abundant “hot spots” with greatly enhanced local electromagnetic field are promoted densely on the mesocage surface by the plenty of deep and narrow gaps and the hollow structure. The single‐particle SERS signal generated by the Ag mesocage has an enhancement factor of approximately 10⁹, which is approximately four times higher than the Ag mesocage synthesized using single‐crystal Ag₂O particle as a template. Meanwhile, this signal displays a linear dependence on the detected analyte concentration, sensitively down to 1.0 × 10^?12 m .     

同台竞技 各展风采——首届全国高等学校物理基础课程青年教师讲课比赛感想

首届＂高等教育杯＂全国高等学校物理基础课程青年教师讲课比赛全国决赛于2014年7月21日在四川大学进行.本次讲课比赛分为省预赛、地区复赛以及全国决赛.作为决赛评委以及陕西省预赛、西北地区复赛的具体组织者之一,笔者认为,本次比赛非常成功,产生了影响,积累了经验,通过预赛、复赛、决赛3个环节扩大了参与学校及选手的数量,达到了预期的目的.下面是我个人的体会与感想.     

时间整形飞秒激光诱导熔融硅表面纳米周期条纹的电子动力学研究

研究了时间整形飞秒激光在熔融硅表面诱导纳米周期条纹结构的电子动力学过程.通过引入非线性电离机制和表面等离子激元的瞬态作用机理,建立了关于时间整形飞秒激光诱导和调控熔融硅表面纳米周期条纹结构的电子动力学模型,并应用该模型研究获得了纳米条纹周期与时间整形脉冲时间间隔的定量关系.理论研究结果表明,通过调节时间整形脉冲的时间间隔可以实现操控表面等离子激元与激光瞬态干涉过程中的波矢配对,最终可实现对诱导的纳米条纹周期的调控.此模型预测得到的纳米条纹周期与实验结果符合得很好.该研究对于深刻理解整形脉冲链诱导材料表面纳米周期结构的电子动力学操纵机制以及对条纹周期的调控都具有重要的理论价值.     

The synthesis of Tempol–phenol derivatives and their protection against radical-induced damage

Stable nitroxides are potential antioxidant drugs. In this study, we have linked nitroxide (Tempol) to phenol with the aim of improving radioprotective activity. The radical scavenging activities of four Tempol–phenol conjugates were evaluated in L-02 and MCF-7 cells survival assays. A differential protection in normal cells as compared to tumor cells was confirmed. In addition, the protective effect of these compounds was demonstrated in a greater increase in peripheral WBC, ANC, AMC, and platelet counts in an in vivo rat model. It might be possible to develop them into a possible agent for radical injury.     

Enhanced Photocatalytic Activity of Thienyl-Porphyrins-TiO2 for Degradation of 4-Nitrophenol

5‐Mono‐(2‐thienyl)‐10,15,20‐triphenyl porphyrin (H₂MTP) and its Co(II), Cu(II), Zn(II) metalloporphyrins (CoMTP, CuMTP, ZnMTP) were synthesized and characterized spectroscopically. The corresponding Co(II), Cu(II), Zn(II) metalloporphyrins‐TiO₂ photocatalysts were then prepared and characterized by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), UV‐vis spectra and FT‐IR. The photocatalytic activities of these photocatalysts were investigated by testing the photodegradation of 4‐nitrophenol (4‐NP) in aqueous solution under irradiation with high‐pressure mercury lamp and metal halide lamp respectively. The results indicated that these metalloporphyrins greatly enhanced the photocatalytic efficiency of bare TiO₂ in degradating the 4‐NP, and CuMTP‐TiO₂ exhibited the highest photocatalytic activity of all photocatalysts. In addition, the first order rate constants of these photocatalytic reactions were calculated.     

基于投影寻踪原理的建筑业综合实力评价分析

在分析影响建筑业综合实力因素的基础上,选择了规模效益水平、技术装备水平、效率水平三个方面共12个评判指标,建立了建筑业综合实力评价的投影寻踪分类模型(PPC),并利用基于实数编码的加速遗传算法(RAGA)求解最佳投影方向.根据投影值的大小对地区建筑业综合实力进行评价分析.PPC模型具有稳健性好、投影值准确度高、评价结果...     

Impulsive synchronization of a general nonlinear coupled complex network

This paper investigates impulsive synchronization of a general nonlinear coupled complex network. Based on the comparison theory of impulsive differential system, some novel synchronization criteria are derived, and impulsive controllers are designed simultaneously. Finally, numerical simulations demonstrate the effectiveness of the proposed synchronization criteria.