Simple and controllable synthesis of highly dispersed Pt-Ru/C catalysts by a two-step spray pyrolysis process

A carbon supported Pt-Ru catalyst with uniform distribution and small average size of the Pt-Ru particles was synthesized using a two-step spray pyrolysis (SP) method; the electrocatalytic activity of the prepared catalyst for methanol oxidation is better than that of the standard commercial catalyst.     

基于SAR子孔径序列图像配准的海洋动态信息获取

合成孔径雷达(SAR)在海洋遥感中发挥着重要的作用。海洋的动态信息如洋流的运动和海浪的传播等是海洋信息中的重要组成部分。但是通常的SAR海洋图像信息处理是将SAR图像作为海面的瞬时状态进行处理,无法获取海洋的动态信息。该文采用子孔径分割的方法获取海面的具有连续时间间隔的序列图像,通过改进的相位相关法对序列图像间的对应部分进行亚像素级配准,获取了海面各个部分的海浪纹理信息运动的速度大小和方向。仿真实验表明改进的配准方法具有1/10像素精度和极强的噪声鲁棒性。对序列图像间相同的舰船目标,分别采用该文提出的配准法与较成熟的"尾迹法"计算的舰船速度基本一致,证明了该文方法的有效性。     

GPS接收机测量电离层TEC的数据处理方法

介绍了应用ＧＰＳ卫星接收机ＳＮＲ－８Ｃ进行电离层ＴＥＣ观测的数据处理方法，并给出了部分数据处理结果。其中包括应用ＧＰＳ双频信号进行ＴＥＣ计算的原理，应用卫星星历参数计算各时刻电离层质心点的经度及卫星仰角和方位角，以及ＴＥＣ的周日变化，逐日变化及一次卫星通过时ＴＥＣ的时空变化结果，讨论了该方法的误差来源及与ＮＮＳＳ方法，法拉第旋转测量ＴＥＣ的比较。应用ＧＰＳ方法测量ＴＥＣ具有很大的优点，具有高精度及     

Room temperature fabrication of hollow ZnS and ZnO architectures by a sacrificial template route

Hollow ZnS and ZnO architectures are fabricated by employing Zn(5)(CO(3))(2)(OH)(6) microspheres as the sacrificial template. Zn(5)(CO(3))(2)(OH)(6) microspheres can be effectively converted into the core/shell structured ZnO/ZnS composites (in the Na(2)S solution) and hollow ZnO architectures (in the KOH solution), by a spontaneous ion replacement reaction at room temperature. Removing the core by the KOH treatment of core/shell structured ZnO/ZnS, hollow ZnS spheres with different shell thicknesses can be effectively achieved. The obtained hollow ZnO architectures exhibit unique geometrical shapes, and their walls are composed of nanocrystals, which are connected to each other to form their hemispherical or circular shape. A possible formation process from Zn(5)(CO(3))(2)(OH)(6) microspheres to core/shell structured ZnO/ZnS composites is proposed by arresting a series of intermediate morphologies.     

Fourier–Jacobi periods and the central value of Rankin–Selberg L-functions

In this paper, we propose a conjectural formula, relating the Fourier–Jacobi periods of automorphic forms on U(n)×U(n) and the central value of some Rankin–Selberg L-function. This can be viewed as a refinement of the Gan–Gross–Prasad conjecture for unitary groups. We then use the relative trace formula technique to prove this conjectural formula in some cases. We also have give applications to the conjecture of Ichino–Ikeda and N. Harris on the Bessel period of automorphic forms on unitary groups.     

非保守力学系统Nielsen方程的形式不变性

研究非保守力学系统Nielsen方程的形式不变性.给出非保守力学系统Nielsen方程的形式不变性的定义和判据,研究形式不变性和Noether对称性的关系,并举例说明结果的应用 关键词： 非保守力学系统 Nielsen方程 形式不变性 Noether对称性     

Bi_2MoO_6/BiVO_4异质结的水热合成和可见光催化活性(英文)

采用一步水热法制备Bi2MoO6/BiVO4复合光催化剂.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)等手段对其晶体结构和微观结构进行了表征.结果表明,Bi2MoO6纳米粒子沉积在BiVO4纳米片表面从而形成异质结结构.紫外-可见漫反射光谱(UV-Vis DRS)表明所制备的Bi2MoO6/BiVO4异质结较纯相Bi2MoO6和BiVO4对可见光吸收更强.由于形成异质结结构及其光吸收性能使Bi2MoO6/BiVO4光催化活性有较大提高.可见光下(λ420 nm)光催化降解罗丹明B(RhB)实验结果表明,Bi2MoO6/BiVO4光催化活性较纯相Bi2MoO6和BiVO4高.Bi2MoO6/BiVO4样品光催化性能提高的原因是Bi2MoO6和BiVO4形成异质结,从而有效抑制光生电子-空穴对的复合,增大了可见光吸收范围及比表面积.     

A Dual‐Phase Ceramic Membrane with Extremely High H2 Permeation Flux Prepared by Autoseparation of a Ceramic Precursor

A novel concept for the preparation of multiphase composite ceramics based on demixing of a single ceramic precursor has been developed and used for the synthesis of a dual‐phase H₂‐permeable ceramic membrane. The precursor BaCe_0.5Fe_0.5O_3?δ decomposes on calcination at 1370 °C for 10 h into two thermodynamically stable oxides with perovskite structures: the cerium‐rich oxide BaCe_0.85Fe_0.15O_3?δ (BCF8515) and the iron‐rich oxide BaCe_0.15Fe_0.85O_3?δ (BCF1585), 50 mol % each. In the resulting dual‐phase material, the orthorhombic perovskite BCF8515 acts as the main proton conductor and the cubic perovskite BCF1585 as the main electron conductor. The dual‐phase membrane shows an extremely high H₂ permeation flux of 0.76 mL min^?1 cm^?2 at 950 °C with 1.0 mm thickness. This auto‐demixing concept should be applicable to the synthesis of other ionic‐electronic conducting ceramics.     

螺桨烷

本文综述了螺桨烷的最新进展,详细叙述了螺桨烷的合成、结构与性质,特別是小螺桨烷的张力能及桥头-桥头碳-碳单键的价键状态。     

2,4-二硝基苯胺与牛血清白蛋白相互作用的研究

通过荧光和紫外光谱法研究了2,4-二硝基苯胺同牛血清白蛋白(BSA)的相互作用. 2,4-二硝基苯胺对牛血清白蛋白的内源荧光具有强烈的猝灭作用. 二者之间形成不发荧光的复合物是导致荧光猝灭的主要原因. 计算了其结合常数和结合位点数. 紫外光谱法进一步证明了其猝灭机理为静态猝灭. 根据能量转移理论计算了作用距离(3.13 nm). 同步荧光的结果表明2,4-二硝基苯胺的存在改变了牛血清白蛋白的分子构象.