Application of longitudinal generalized magneto-optical ellipsometry in magnetic ultrathin films

The longitudinal generalized magneto-optical ellipsometry(GME) method is extended to the measurement of threelayer ultrathin magnetic films. In this work, the theory of the reflection matrix is introduced into the GME measurement to obtain the reflective matrix parameters of ultrathin multilayer magnetic films with different thicknesses. After that, a spectroscopic ellipsometry is used to determine the optical parameter and the thickness of every layer of these samples, then the magneto-optical coupling constant of the multilayer magnetic ultrathin film can be obtained. After measurements of a series of ultrathin Fe films, the results show that the magneto-optical coupling constant Q is independent of the thickness of the magnetic film. The magneto-optical Kerr rotations and ellipticity are measured to confirm the validity of this experiment. Combined with the optical constants and the Q constant, the Kerr rotations and ellipticity are calculated in theory. The results show that the theoretical curve fits very well with the experimental data.     

随机环境中受控分枝过程的极限定理

讨论了随机环境中受控分枝过程{Z_n:n∈N}的极限问题.给出了过程在{S_n:n∈N}下的规范化过程{W_n:n∈N}几乎处处收敛、L~1收敛和L~2收敛的充分条件,以及过程{W:n∈N}的极限非退化于0的充分条件和必要条件,得到了过程在{I_n:n∈N}下的规范化过程{W_n:n∈N}几乎处处收敛和L~1收敛的充分条件.     

制备均一形貌的长二氧化钛纳米管

在温和的水热条件下,用碱溶液处理不同粒径的锐钛矿相和金红石相二氧化钛 纳米粉体,得到了不同形貌的二氧化钛纳米管,并用TEM,XRD,FT-Raman和BET等 对其进行了表征。金红石相的超细纳米晶有利于形成均一形貌的纳米管,用粒径仅 为7.2 nm的金红石相纳米粉体为前驱体得到了长度为500 nm的长二氧化钛纳米管。 用纳米晶反应活性对晶粒尺寸的依赖性及晶相稳定性解释了长纳米管的形成机理。     

Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

Lidar （Light detection and ranging） has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing.     

多跳噪声量子纠缠信道特性及最佳中继协议

在量子通信网络中, 最佳中继路径的计算与选择策略是影响网络性能的关键因素. 针对噪声背景下量子隐形传态网络中的中继路径选择问题, 本文首先研究了相位阻尼信道及振幅阻尼信道上的纠缠交换过程, 通过理论推导给出了两种多跳纠缠交换信道上的纠缠保真度与路径等效阻尼系数. 在此基础上提出以路径等效阻尼系数为准则的隐形传态网络最佳中继协议, 并给出了邻居发现、量子链路噪声参数测量、量子链路状态信息传递、中继路径计算与纠缠资源预留等工作的具体过程. 理论分析与性能仿真结果表明, 相比于现有的量子网络路径选择策略, 本文方法能获得更小的路径平均等效阻尼系数及更高的隐形传态保真度. 此外, 通过分析链路纠缠资源数量对协议性能的影响, 说明在进行量子通信网设计时, 可以根据网络的规模及用户的需求合理配置链路纠缠资源.     

非水介质毛细管电泳电化学检测日夜百服宁中的有效成分

用非水毛细管电泳电化学检测法分离检测了日夜百服宁中的有效成分，研究了电极电位，不同浓度的甲酰胺（FA），电解液浓度和酸度，电泳电压及进样时间对电泳分离的影响，得到了较为优化的测定条件。实验结果表明，在25mmol/L Tris-25mmol/L H3BO3(表观pH=8.5)运行介质中，日夜百服宁中的4种有效成分即扑热息痛（AP），盐酸伪麻黄碱（PH），氢溴酸右美沙芬（DM）和扑尔敏（CM）在12min内完全分离，检测电位为＋0．9V(vs.SCE)。线性范围分别为AP 0．5－200mg/L;PH 0.8-300mg/L;DM2.5-350mg/L;CM0.5-330mg/L；检测限分别为AP0.1mg/L;PH0.55mg/L;DM1mg/L;CM0.2mg/L。     

Ta3N5 nanoparticles with enhanced photocatalytic efficiency under visible light irradiation

Nanocrystalline Ta(3)N(5) particles with a surface area of more than 33 m(2)/g were synthesized by nitridation of nanosized Ta(2)O(5) particles using NH(3) as the reactant gas. It was found that nanocrystalline Ta(2)O(5) was converted into Ta(3)N(5) completely (by X-ray diffraction, XRD) at 700 degrees C within 5.0 h, which was much lower than the temperature 900 degrees C for the complete nitridation of micrometer-sized Ta(2)O(5) powder. The oxide precursor and the resulting nitride were characterized by XRD analysis, transmission electron microscopy, UV-vis diffuse reflectance spectra, and BET surface area techniques. The nitrogen contents in the prepared Ta(3)N(5) powders were quantitatively determined with a CHN elemental analyzer. Nanocrystalline Ta(3)N(5) showed an absorption edge of around 600 nm, and Ta(3)N(5) in the size of about 26 nm exhibited a blue shift of 15 nm in the adsorption edge. The photocatalytic activity of the prepared Ta(3)N(5) under UV-vis and visible light irradiation was compared to that of nanocrystalline TiO(2-x)N(x) using the photocatalytic degradation of methylene blue (MB) as a model reaction. The Ta(3)N(5) nanoparticles showed the significantly enhanced photocatalytic activity for the degradation of MB in comparison with the larger-sized Ta(3)N(5). Moreover, the nanocrystalline Ta(3)N(5) showed much higher photocatalytic activity under visible light irradiation compared with TiO(2-x)N(x) in the same size.     

Chiral equivariant cohomology I

We construct a new equivariant cohomology theory for a certain class of differential vertex algebras, which we call the chiral equivariant cohomology. A principal example of a differential vertex algebra in this class is the chiral de Rham complex of Malikov-Schechtman-Vaintrob of a manifold with a group action. The main idea in this paper is to synthesize the algebraic approach to classical equivariant cohomology due to H. Cartan,² with the theory of differential vertex algebras, by using an appropriate notion of invariant theory. We also construct the vertex algebra analogues of the Mathai-Quillen isomorphism, the Weil and the Cartan models for equivariant cohomology, and the Chern-Weil map. We give interesting cohomology classes in the new theory that have no classical analogues.     

A dual-parametric finite element method for cavitation in nonlinear elasticity

A dual-parametric finite element method is introduced in this paper for the computation of singular minimizers in the 2D cavitation problem in nonlinear elasticity. The method overcomes the difficulties, such as the mesh entanglement and material interpenetration, generally encountered in the finite element approximation of problems with extremely large expansionary deformation. Numerical experiments show that the method is highly efficient in the computation of cavitation problems. Numerical experiments are also conducted on discrete problems without the radial symmetry to show the validity of the method to more general settings and the potential of its application to the study of mechanism of cavity nucleation in nonlinear elastic materials.