全氟辛酸致小鼠肝脏氧化损伤的实验

研究了低（1mg/kg/d）、中（5mg/kg/d）、高（25mg/kg/d）三个剂量组全氟辛酸（Perfluorooctanoic acid,PFOA）致小鼠肝脏脂质过氧化损伤的作用.结果发现,PFOA能抑制小鼠体重的增长,对肝组织造成一定的脂质过氧化损伤.各组小鼠出现不同程度的体重增长缓慢甚至减轻,中、高剂量组出现明显的减轻（P＜0.01）;低、中、高剂量组肝脏系数,均明显高于对照组（P＜0.01）;与对照组相比,各剂量组的肝组织中MDA、NO及LDH含量明显增高,SOD、SDH及GSH-Px活性均明显降低（P＜0.05）.     

Pulse broadening of the femtosecond pulses in a Gaussian beam passing an angular disperser

A general analytical formula has been found to describe the evolution of the pulse width of the femtosecond pulses in a Gaussian beam after passing an angular disperser without the assumption of well collimation. This formula is experimentally verified by measuring the pulse width with an autocorrelator based on two-photon absorption. It is found that the effect of the spectral lateral walk-off and group delay dispersion on the pulse-width evolution, and its dependence on the distance traveled, are substantially different when the beam has not been well collimated than from when it has been collimated. These differences result from the decaying nature of the angular dispersion of the Gaussian beam sent across a distance.     

α-Fe纯I型裂纹扩展中位错形成过程的三维分子动力学模拟

通过分子动力学方法模拟了三维 α-Fe I型裂纹的单向拉伸实验中的裂纹扩展过程。研究了在不同温度下裂纹扩展时位错的形成过程和断裂机理。计算结果表明,裂纹扩展过程是位错不断发射的过程。 裂纹尖端附近先形成无位错区和层错,当裂纹处应力增加到KI=0.566 MPam1/2时,裂纹尖端附近的某一层原子会逐渐分叉形成两层原子,分层后的原子层继续分离形成位错;当应力KI 达到0.669MPam1/2时第一个位错发射。随着温度的升高,临界应力强度因子逐渐降低,同时位错发射也相应地加快。     

部分相干部分偏振电磁束通过光阑透镜的传输

基于广义斯托克斯参量,推导出了部分相干部分偏振高斯谢尔模型(GSM)电磁束通过光阑透镜后交叉谱密度矩阵、光强、偏振度、偏振椭圆的方位角及椭偏角的解析表达式,并用以研究菲涅耳数、自相关和互相关长度以及束腰宽度对焦移和偏振特性的影响。对主要数值计算结果做了物理解释。     

Effective control over the dual-color emitted light waves from one-dimensional random media pumped by Femtosecond-Lasing Pulses

The spectral property of dual-color random laser is investigated by simultaneously solving Maxwell’s equations and rate equations of electronic population in which the pumping rate is described by a time function with duration of hundreds of femtoseconds. Results show that the delay time and peak intensity of the emitted light depends strongly on the pumping process. An effective optimization method is proposed to exercise control over the dual-color laser emission from the dye solution with scattering nano-particles. It is demonstrated numerically that the controllable single mode operation of a dual-color random laser by choosing the proper pump profile and pumping region. The present work enriches the knowledge about random lasers and offers more guidance for relevant experiments.     

Behavior of viscous solutions in Lagrangian formulation

In this paper, the behavior of shock-capturing methods in Lagrangian coordinate is investigated. The relation between viscous shock and inviscid one is analyzed quantitatively, and the procedure of a viscous shock formation and propagation with a jump type initial data is described. In general, a viscous shock profile and a discontinuous one include different energy and momentum, and these discrepancies result in the generation of waves in all families when a single wave Riemann problem (shock or rarefaction) is solved. Employing this method, some anomalous behavior, such as, viscous shock interaction, shock passing through ununiform grids, postshock oscillations and lower density phenomenon is explained well. Using some classical schemes to solve the inviscid flow in Lagrangian coordinate may be not adequate enough to correctly describe flow motion in the discretized space. Partial discrepancies between von Neumann artificial viscosity method and Godunov method are exhibited. Some reviews are given to those methods which can ameliorate even eliminate entropy errors. A hybrid scheme based on the understanding to the behavior of viscous solution is proposed to suppress the overheating error.     

Spectroscopic properties of Er<Superscript>3+</Superscript> in Sc:LiNbO<Subscript>3</Subscript> crystal

The results of Er³⁺ ion spectroscopic analysis in Sc:LiNbO₃ crystals were reported. The line strengths from the ground state to the excited state were evaluated from the measured unpolarized absorption spectrum and analyzed by using standard Judd–Ofelt theory. For Sc(3 mol. %):Er (1 mol. %):LiNbO₃ crystal, the obtained intensity parameters are: Ω₂=3.72×10^-20 cm², Ω₄=1.07×10^-20 cm², and Ω₆=0.98×10^-20 cm². The fluorescence spectra and microsecond time-resolved spectra were investigated in the visible region. The excited state absorption transition strengths at 800 nm excitation were evaluated based on Judd–Ofelt theory. The results obtained here were compared to results from other research on Er:LiNbO₃ crystals. PACS 71.20.Eh; 77.84.Dy; 42.70.Hj; 42.62.Fi; 42.65.Ky     

Fabrication of gradient refractive index ball lenses using the method of combination of ion exchanging and sagging

Based on the Fick’s diffusion equations, the distribution function of refractive index of a gradient refractive index ball lens (GRIN ball lens/GBL) is derived. Lithium containing silicate glass is fabricated and GRIN ball lenses (GBLs) which diameters are from 0.3 mm to 3.0 mm are made by the method of combination of Ion exchanging and sagging in sodium nitrate. Refractive index profiles of these GBLs are measured by interferometer, and the performances such as effective focal length (EFL), back focal length (BFL) and numerical aperture (NA) between GBLs and homogeneous ball lenses (HBLs) are compared. Results show that the distribution of the index of refraction is parabolic curve and its Δn is about 0.0002, the performances of the former are super to the latter.     

Thermal desorption characteristic of helium ion irradiated nickel-base alloy

The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel.To evaluate its stability of helium damage and retention,helium ions with different energy of 80 keV and 180 keV were introduced by ion implantation to a certain dose(peak displacement damage 1-10 dpa).Then thermal desorption spectroscopy(TDS)of helium atoms was performed to discuss the helium desorption characteristic and trapping sites.The desorption peaks shift to a lower temperature with increasing dpa for both 80 keV and 180 keV irradiation,reflecting the reduced diffusion activation energy and faster diffusion within the alloy.The main release peak temperature of 180 keV helium injection is relatively higher than that of 80 keV at the same influence,which is because the irradiation damage of 180 keV,helium formation and entrapment occur deeper.The broadening of the spectra corresponds to different helium trapping sites(He-vacancies,grain boundary)and desorption mechanisms(different Hen Vm size).The helium retention amount of 80 keV is lower than that of 180 keV,and a saturation limit associated with the irradiation of 80 keV has been reached.The relatively low helium retention proves the better resistance to helium bubbles formation and helium brittleness.     

掺杂Fe、F对ZnO电子结构和光学性质的影响

本文采用密度泛函理论框架下的第一性原理平面波超软赝势法,建立了Zn16O16、Zn15Fe1O16、Zn16O15F1、Zn15Fe1O15F1超晶胞,对掺杂前后ZnO超晶胞的能带结构分布、光学性质进行了计算与分析。计算结果表明：共掺杂Fe、F体系的形成能比单掺杂更小,稳定性更高;共掺杂体系的共价性最弱,更利于光生电子-空穴对的分离,且共掺杂体系的杂质能级数变得更为密集,电子更容易从低能级跃迁到高能级,进而提高光催化活性;Fe3+的掺入导致费米能级进入导带,产生莫特相变,使之导电性增强;共掺杂体系的介电函数虚部向低能方向移动,在可见光区域的吸收峰值明显增大,说明Fe、F共掺杂是一种很好的光催化材料。