Spectroscopic Study of Laser-Induced Cu Plasma With and Without the Confinement of a Substrate

Optical emission spectroscopic studies have been carried out on the laser-induced copper plasma generated in the process of laser-driven flyer (with the substrate confinement). The copper plasma in the air (without the substrate confinement) has also been researched in order to know the differences between the plasma with the confinement and that without the confinement. The plasma is assumed to be in local thermodynamic equilibrium. The result shows that, under the same laser fluence, the plasma exists a longer time with the confinement. The time-resolved electron temperature and density with the confinement are higher than those with no confinement. The substrate deposited with Cu foil plays an important role in enhancing the temperature and the density of the plasma. The electron temperature and density with confinement increase with a larger scope as the laser fluence increases than that with no confinement.      

Nanodosimetry of 125I – Auger electrons – Experiment and modeling

The experiment with ¹²⁵I-Auger electrons, interacting with gaseous nitrogen with size equivalent to segment of DNA in mass per unit area scale, are described. The discrete ionization cluster-size distributions have been obtained. The shapes of which are definitely determined by the size of the interaction volumes. The volume sizes studied in the present work are comparable with a segment of DNA and of nucleosome. The experiments have been carried out with the set up, called Jet Counter, and are the first cluster-size distributions as yet measured for an Auger-electron emitter like ¹²⁵I. The experimental results have been compared with those obtained by Monte Carlo simulation. The results for ¹²⁵I have been compared with calculated cluster size distribution for ¹³¹I.     

基于等阻抗差分段法的变阻抗线电路模拟

新型Z箍缩驱动源系统采用变阻抗线结构形式的径向阻抗变换器进行能量传递和变换,为了获得最大的能量效率,需要应用电路模拟方法研究变阻抗线传递功率的特性。采用了等阻抗差分段法对变阻抗线进行了建模计算,与以往的等长度分段方法比较,在相同的分段数量下,等阻抗差分段法在阻抗变化的连续性上优于等长度分段法。给出了具有指数形式的变阻抗线的算例,分别采用两种分段法进行了计算,对计算结果的比较表明:等阻抗差分段法可以使计算更快地收敛到真实解。     

40Cr钢表面激光熔覆层的磨损性能

为研究模具钢熔覆层的磨损性能,采用铁基粉在40Cr钢表面进行激光熔覆,以激光熔覆层为上试样,GCr15钢珠为下试样,采用HT－500磨损试验机进行摩擦磨损试验,并与40Cr基体的磨损性能相对比。利用表面形貌仪测量磨痕深度和宽度。研究结果表明：载荷小于250 g时,相同载荷下基体的摩擦系数大。载荷小于300 g时,随磨损时间延长,熔覆层、基体的摩擦系数都随着载荷增加而减小。当载荷为300 g时,基体的摩擦系数在0.563～0.589之间变化,平均值为0.576,且随时间逐渐升高,耐磨性变差;熔覆层的磨擦系数在0.431～0.457之间变化,平均摩擦系数为0.444,磨痕深度和宽度分别是0.65 mm和1.096 μm,且随时间逐渐下降,表现了良好的耐磨性能。当载荷增加到500 g时,平均摩擦系数和磨痕深度比300 g时分别增加了75％和47倍,且摩擦系数逐渐升高,磨损性能下降。     

基于等阻抗差分段法的变阻抗线电路模拟

新型Z箍缩驱动源系统采用变阻抗线结构形式的径向阻抗变换器进行能量传递和变换,为了获得最大的能量效率,需要应用电路模拟方法研究变阻抗线传递功率的特性。采用了等阻抗差分段法对变阻抗线进行了建模计算,与以往的等长度分段方法比较,在相同的分段数量下,等阻抗差分段法在阻抗变化的连续性上优于等长度分段法。给出了具有指数形式的变阻抗线的算例,分别采用两种分段法进行了计算,对计算结果的比较表明:等阻抗差分段法可以使计算更快地收敛到真实解。     

40Cr钢表面激光熔覆层的磨损性能

 为研究模具钢熔覆层的磨损性能,采用铁基粉在40Cr钢表面进行激光熔覆,以激光熔覆层为上试样,GCr15钢珠为下试样,采用HT－500磨损试验机进行摩擦磨损试验,并与40Cr基体的磨损性能相对比。利用表面形貌仪测量磨痕深度和宽度。研究结果表明：载荷小于250 g时,相同载荷下基体的摩擦系数大。载荷小于300 g时,随磨损时间延长,熔覆层、基体的摩擦系数都随着载荷增加而减小。当载荷为300 g时,基体的摩擦系数在0.563～0.589之间变化,平均值为0.576,且随时间逐渐升高,耐磨性变差;熔覆层的磨擦系数在0.431～0.457之间变化,平均摩擦系数为0.444,磨痕深度和宽度分别是0.65 mm和1.096 μm,且随时间逐渐下降,表现了良好的耐磨性能。当载荷增加到500 g时,平均摩擦系数和磨痕深度比300 g时分别增加了75％和47倍,且摩擦系数逐渐升高,磨损性能下降。     

Optical and electrical properties of InGaZnON thin films

The substrate temperature(T_s)and N_2 partial pressure(P_(N2))dependent optical and electrical properties of sputtered InGaZnON thin films are studied.With the increased T_s and P_(N2),the thin film becomes more crystallized and nitrified.The Hall mobility,free carrier concentration(Ne),and electrical conductivity increase with the lowered interfacial potential barrier during crystal growing.The photoluminescence(PL)intensity decreases with the increased Ne.The band gap(Eg)narrows and the linear refractive index(n1)increases with the increasing concentration of N in the thin films.The Stokes shift between the PL peak and absorption edge decreases with Eg.The n1,dispersion energy,average oscillator wavelength,and oscillator length strength all increase with n1.The single oscillator energy decreases with n1.The nonlinear refractive index and third order optical susceptibility increase with n1.The Seebeck coefficient,electron effective mass,mean free path,scattering time,and plasma energy are all Ne dependent.     

Mechanisms of the oxidation of defect-free surfaces of carbon nanostructures: the influence of surface curvature

This work is concerned with reaction paths in the interaction of carbon defect-free nanostructures with different surface curvatures (graphene, tubulenes, and fullerene C₆₀) with atomic and molecular oxygen. The interaction energies of atoms were calculated by the density functional theory method using the basis set of plane waves and the VASP package. The potential surface of reactions with molecular oxygen was studied by the nudged elastic band method. The energy parameters of the reaction (released energy and barrier) strongly depended on the curvature of carbon structure surfaces. The interaction of atomic oxygen in the ground state with the surface of carbon nanostructures is an exothermic reaction. The barrier to the reaction with molecular oxygen (0.5–2.5 eV) decreases as the curvature of nanostructure surfaces increases. The calculation results are in agreement with the experimental data and other ab initio calculations.     

掺氮金刚石的光学吸收与氮杂质含量的分析研究

研究了金刚石光学特性与氮杂质及其含量的关系,从传统的金刚石氮含量标定方法出发,修正了金刚石氮含量的计算方法,并且用添加叠氮化钠的原料在六面顶压机上进行了高氮含量金刚石的制备研究.随着体系中叠氮化钠的添加,金刚石红外吸收谱在800—1400 cm^-1范围的吸收强度相对于基线不断升高,这表明金刚石中存在的氮含量在随着叠氮化钠添加而升高,金刚石在单声子区域吸收强度大大增强.用含叠氮化钠的原料制备的金刚石呈现绿色、墨绿色甚至黑色,颜色的深浅依赖于叠氮化钠添加的多少.傅里叶红外光谱测试结果表明 关键词： 金刚石 光学材料 杂质 红外     

注蒸汽井井筒内参数计算新模型

从动量定理角度出发建立求解蒸汽压降方程,而从能量守恒角度出发建立求解蒸汽干度变化的方程,采用节点分析方法和数值计算方法对模型求解.计算过程中借鉴传统的气液两相流Beggs-Brill方法计算水蒸汽混合物的物性参数.通过对辽河油田齐40块和杜80块10口井井筒的压力、温度和干度分布计算表明该模型计算精度较高.     

Scattering of 21.1 MeV polarized protons from 89Y

The elastic and inelastic scattering of 21.1 MeV protons from ⁸⁹Y have been investigated. The excited states with a collective nature can be described quite well with standard OM and DWBA techniques. The transitions to the low-lying single-particle states are described with antisymmetrized microscopic DWBA including tensor and spin-orbit forces. The agreement with the experimental data is encouraging.     

L型脉冲形成网络的仿真与实验研究北大核心CSCD

研究了L型连接结构对脉冲形成网络输出波形的影响。采用有限积分法,对L型连接结构的脉冲形成网络进行三维建模和仿真,并将其与直线型连接结构的脉冲形成网络仿真结果进行比较。结果表明:L型结构的脉冲形成网络前沿与直线型结构基本一致,约为40ns,半高宽为168ns,比直线型小7ns,平顶处较直线型结构有所波动,表现为平顶后段幅度升高。通过对两种连接结构的脉冲形成网络进行高压实验,验证了仿真结果。在脉冲功率驱动源结构紧凑化的工程应用中,L型连接结构的输出波形能基本满足要求。     

L型脉冲形成网络的仿真与实验研究

研究了L型连接结构对脉冲形成网络输出波形的影响。采用有限积分法,对L型连接结构的脉冲形成网络进行三维建模和仿真,并将其与直线型连接结构的脉冲形成网络仿真结果进行比较。结果表明：L型结构的脉冲形成网络前沿与直线型结构基本一致,约为40 ns,半高宽为168 ns,比直线型小7 ns,平顶处较直线型结构有所波动,表现为平顶后段幅度升高。通过对两种连接结构的脉冲形成网络进行高压实验,验证了仿真结果。在脉冲功率驱动源结构紧凑化的工程应用中,L型连接结构的输出波形能基本满足要求。     

Macroscopic Quantum State in Optically Driven Semiconductors: Crossover from Electron-Hole BCS to Exciton Bose Condensation

Luminescence spectra from high-density electron-hole ( e-h ) systems at zero temperature are studied. The calculated spectra clearly show the crossover between the e-h BCS state and the exciton Bose-Einstein condensate; this behavior analyzed neither with the BCS-like mean-field theory nor with the interacting Boson model. The strong phase fluctuation associated with the center-of-mass motion of e-h pairs is considered with the generalized random phase approximation combined with the Bethe-Salpeter equation for e-h pairs. The calculated spectra show that the broad spectral components from the e-h BCS state splits into P- and P 2 -lines with decreasing e-h density. The calculated density dependence of the band-gap renormalization excellently agrees with experiments for CuCl and ZnO.     

Jefferson国家实验室（JLab）简介

简要介绍了JLab的一般情况、JLab高性能加速器CEBAF（Continue Electron Beam Accelerator Facility）和3个实验大厅的主要实验设备。着重介绍了CEBAF的连续束流与实验大厅的高密靶及高精度谱仪结合所得到的高精度实验结果，介绍了JLab实验室要解决的根本问题、相应的物理课题以及中国组正在参与数据分析和正在做的实验。最后简要介绍了CEBAF升级至12 GeV及其带来新的研究机会和新的物理课题，以及中国组与JLab的合作情况。The general situation of JLab is briefly introduced. The accelerator CEBAF with high quality and the equipments in the three Halls are described. The experimental results with high accuracies, which were obtained by using continue beam with high energy resolution, and high density target and high resolution spectrometers in the halls, are presented with two examples. The basic physics problems which JLab intends to solve, and the programs which JLab completed and is going to do, are stated. The programs which China group is cooperating with other groups are emphasized. The energy escalation for CEBAF will bring new opportunities for scientific researches.     

Alteration of the Binding Strength of Dronedarone with Bovine Serum Albumin by β-Cyclodextrin: A Spectroscopic Study

We report the influence of β-cyclodextrin on the binding of the drug dronedarone with bovine serum albumin. The stoichiometry, the binding constant, and the mode of binding of the derivative with β-cyclodextrin are studied by UV–Visible absorption, fluorescence, and 2 Dimensional Rotating Frame Overhauser Effect Spectroscopy (2D ROESY NMR) spectroscopic techniques. The structure of the 1:1 inclusion complex is proposed. The binding of free dronedarone with bovine serum albumin and β-cyclodextrin-bound dronedarone are studied by fluorescence quenching and Förster resonance transfer. The decreased magnitude of the Stern–Volmer constant and the binding constant for the interaction of dronedarone with bovine serum albumin in the presence of β-cyclodextrin are articulated. The donor-to-acceptor distances in the presence and the absence of β-cyclodextrin are compared. The binding sites of the dronedarone with bovine serum albumin are reported by molecular modeling. Dronedarone binds to the sub-domain III of bovine serum albumin. The 3-(dibutylaminopropoxy)benzoyl moiety of dronedarone binds with bovine serum albumin. Encapsulation with β-cyclodextrin decreases the binding strength of dronedarone with bovine serum albumin.     

Theory of the Fano resonance in impurity excitation spectra of <Emphasis Type="Italic">p</Emphasis>-GaAs

The features observed in the impurity photoconductivity spectra of gallium arsenide doped with shallow acceptors have been described theoretically. The features are caused by the interaction of holes with polar optical phonons. The Fano resonances associated with both the ground and excited acceptor states have been considered. The calculated widths of the resonances are in agreement with available experimental data.     

星载高分辨率超光谱成像仪分光方式的选择

从多个方面分析了棱镜和光栅色散分光的优缺点,分析结果表明棱镜更适于星载高分辨率超光谱成像仪的分光。在透过率方面,棱镜光谱仪透过率高达95.24％(VNIR),而光栅的衍射效率仅为60%~70%。在杂散光方面,棱镜光谱仪的杂散光可达10－4,而光栅的杂散光为10－2。在0.4 －2.5 范围,棱镜光谱仪相对光栅光谱仪有优越性。在色散线性方面,光栅光谱仪基本线性,棱镜光谱仪的短波非线性问题可通过复合棱镜进行补偿。可靠性方面,棱镜光谱仪较光栅光谱仪有优势;在光谱带宽和成本方面,棱镜光谱仪与光栅光谱仪基本接近。     

Simultaneous features of Wu's slip,nonlinear thermal radiation and activation energy in unsteady bio-convective flow of Maxwell nanofluid configured by a stretching cylinder

This continuation deals with the bioconvection flow of magnetized Maxwell nanofluid over a stretched cylinder in presence of slip effects. The novel features of activation energy and thermal radiation are also encountered to analyze the flow. The higher order slip relations are introduced to inspect the thermal flow problem. The flow model is developed in terms of dimensionless equations via appropriate variables. The numerical simulations are presented with shooting scheme by using MATLAB software. The physical outcomes of interesting parameters are visualized. The observations show that velocity profile reduces with unsteady parameter, curvature constant and second order slip factor. The temperature profile enhanced with first order velocity slip parameter and curvature constant. Moreover, nanofluid concentration reduces with Lewis number and Brownian constant.     

高温铝等离子体X光发射谱实验

 在神光-Ⅱ高功率激光装置上,以束匀滑的第九路钕玻璃二倍频激光均匀辐照薄层铝埋点靶,通过激光烧蚀作用产生较均匀的铝高温等离子体,用平面晶体谱仪在靶面前向和切向同时测量了X光发射谱信号,并将前向发射谱进行了定量化还原处理。利用辐射流体力学程序MULTI-1D首先对等离子体状态进行了模拟计算,然后采用基于碰撞辐射模型的光谱程序对该状态下的光谱开展了计算,并将实验测量光谱与理论计算光谱进行了比较和分析,符合得较好。