Spontaneously generated walking X-shaped light bullets

In quadratic nonlinear media with normal dispersion and nonvanishing group velocity mismatch between fundamental wave and second-harmonic pulses, the wave packets of two harmonics can be locked together in propagation in the form of walking X-shaped light bullets. The output wave packets are developed into X-shaped light bullets with significant group delay time due to mutual dragging and significant shifting in spatiotemporal spectrum due to delayed nonlinear phase shift. We also show that spontaneously generated phase-front tilting can balance the dragging force induced by group velocity mismatch and lead to zero-velocity walking X-shaped light bullets.     

ICP-AES测定向日葵花盘中13种金属元素

向日葵花盘经湿法消解,采用ICP-AES对其中钾、钙、钠、钡、铝、铬、铜、镁、铁、锰、镍、锶、锌13种元素进行测定.对光谱仪的工作条件及分析谱线等测定条件进行了选择,并进行了方法的回收率及精密度试验,其回收率在95％-122％之间.     

纳米ZnO的制备及其在不同牺牲试剂下的光催化产氢性能

采用沉淀法与异相共沸蒸馏技术相结合制备了ZnO纳米粉体,并利用X射线粉末衍射、扫描电镜、透射电镜和液氮吸-脱附等技术对制备的样品进行了分析与表征．考察了Pt的负载量、煅烧温度以及牺牲试剂的种类和浓度对制备的纳米ZnO的光催化产氢效率的影响．结果表明：与其他温度下煅烧获得的产物相比,400 oC煅烧产物表现出最佳的光催化产氢效率,且以甲醇为牺牲试剂时纳米ZnO悬浮体系的光催化产氢效率远高于以三乙醇胺为牺牲试剂时的产氢效率．其原因在于光催化过程中甲醇氧化也对体系的产氢有贡献．此外,探讨了基于实验结果对含甲醇的     

Effect of preheating temperatures on microstructure and optical properties of Na-doped ZnO thin films by sol–gel process

The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band.     

Design and analysis of a novel tunable optical power splitter

A novel tunable optical power splitter,with a Y-branch waveguide based on the total internal reflection and a microprism with tunable index refraction,is presented.Numerical simulation of its optical performance shows that a high dynamic range,low optical loss,and relatively low wavelength-dependence can be achieved.This component offers numerous advantages such as ease for fabrication,low cost,and compact size,which are very useful for potential application in integrated optical devices.     

液体表面张力系数的实验研究

改变液体的浓度可以调控液体的表面张力系数,各种形状膜架的挂膜时间与液体表面张力系数存在着一定的关系,本文对于这两个方面进行了实验研究,得出了相应的结果.此外,溶液的温度和空气的流动对挂膜时间都会产生影响.     

Synthesis of hexagonal monocrystal AlN microtubes and nanowires at low temperature

This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlClh-AlN, microtubes, nanowires,h-AlN, microtubes, nanowiresProject supported by the National Natural Science Foundation of China (Grant No 10474078) and the Science Foundation of the Education Office of Shanxi Province, China.2006-11-23This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature （450℃） under condition of non-solvent system. The grey-white powder of reacting product was characterized by high-resolution transmission electron microscope （HRTEM）, which shows that the powder is long straight-wire morphology with outer diameter from 40nm to 300 nm and length up to several micrometres. The results of both electron diffraction （ED） and x-ray diffraction （XRD） indicate that the AlN microtubes have a pure hexagonal monocrystal tubular structure with the combination of the curled AlN nanobelts. Room-temperature photoluminescence spectrum of the synthesized sample showed an emission peak, which is closely related to the small size of the microtubes.     

Fractional Fokker-Planck Equation with Space and Time Dependent Drift and Diffusion

In this paper, we aim to answer the question proposed by Magdziarz (Stoch. Proc. Appl. 119:3238?C3252, 2009), i.e. we investigate the solution of an anomalous diffusion equation with time and space dependent force and diffusion coefficient. First, we try to find the stochastic representation of this equation, which means the PDF of this stochastic process is rightly the solution of the equation we aim to solve. Then, we also simulate the sample paths of the stochastic process. At last, taking advantage of the stochastic representation method, we employed Monte Carlo method to approximate the solution of the mentioned equation.     

氦原子与一氧化碳分子各向异性势的计算研究

本文用高精度的量子力学ab initio方法计算了氦原子与一氧化碳分子相互作用各向异性势能面,通过三重激发校正耦合簇、二次组态相互作用等方法和不同基组的计算结果比较,并采用BSSE方法消除了基组重叠误差,得到了氦原子与一氧化碳分子体系相互作用各向异性势,然后采用精确度较高的密耦（Close-Coupling）近似方法,研究了氦原子与一氧化碳分子碰撞的散射截面,通过计算得出了该体系碰撞激发微分截面和分波截面,计算得到的微分截面数据与实验值符合较好,说明本文得到的势能面是准确的.