横波直探头的辐射声场

分析了采用2/2型压电复合材料制作的一种水平面内偏振的横波直探头的辐射声场特性,推导了两种表面力源辐射声场的严格解析解,通过数值计算给出了相应声场分布和指向性图,得到了横波垂直辐射指向性,并与实验结果进行了对比。实验所得声场指向性与理论计算结果符合较好,为该换能器的工程应用提供了理论依据。     

Calculation of Interaction Potentials between Spherical and Deformed Nuclei

The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.     

锂金属电池中的复合负极

锂金属具有理论比容量高、电位低等优点,被认为是电极中的“圣杯”。然而,锂金属负极在循环过程当中存在着不可控的枝晶生长、体积膨胀等问题,严重地阻碍了锂金属电池的商业化进程。本综述首先概述了锂枝晶的形成机理,然后对由小及大,自内而外,总结了近年来三种不同层次的锂金属电池复合负极:锂金属负极内部结构的复合、锂金属电池内部结构的复合以及锂金属电池内部环境与外界操作条件的复合。最后,本综述对未来多层次锂金属电池复合负极的前景做出了展望。     

φ150mm菲索干涉仪球面标准具结构分析与设计

在高精度的光学元件面形检测中,为了保证检测的精度,必须对高精度菲索干涉仪的标准镜的自重和温度变形进行严格地控制.针对高精度菲索干涉仪标准镜的精度要求,设计了一种新的标准镜装卡结构.采用有限元方法分析了标准镜在胶接方式下的表面变形情况,参考面表面变形峰谷(PV)值仅为9.6nm,均方根(RMS)值为2.1nm.同时对不同...     

不同产地丹参的紫外光谱鉴别研究

不同溶剂在微波条件下对4种不同产地丹参进行快速提取,用紫外分光光度计对相同溶剂的提取物进行对比研究,发现其紫外光谱存在差异,可用于不同产地丹参的鉴别.     

Stereodynamics of the O(3P) with H2 (D2) (v=0, j=0) reaction

Quasi-classical trajectory theory is used to study the reaction of O(³P) with H₂ (D₂) based on the ground ³A' potential energy surface (PES). The reaction cross section of the reaction O+H₂ → OH+H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters 〈P₂ (j'·k)〉 and several polarized-dependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.     

Stereodynamics of the O（3P） with H2（D2） （ν=0,j=0） reaction

Quasi-classical trajectory theory is used to study the reaction of O(3 P) with H 2 (D 2) based on the ground 3 A″ potential energy surface (PES).The reaction cross section of the reaction O+H 2 →OH+H is in excellent agreement with the previous result.Vector correlations,product rotational alignment parameters P 2 (j · k) and several polarizeddependent differential cross sections are further calculated for the reaction.The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES,arising from various collision energies or mass factors.     

半导体氮化铟(InN)的晶格振动

本文总结了新型半导体InN薄膜晶格振动研究的现状,主要为Raman散射光谱及部分红外光谱的研究结果。重点内容为InN(包括六方纤锌矿结构和立方闪锌矿结构)的布里渊区中心(Γ点)声子结构、电子激发态(等离子激元)与纵光学声子耦合、无序化激发模和晶格振动模的温度、应力效应等,也涉及部分和InN有关的氮化物合金以及超晶格、量子阱和量子点等结构的晶格振动研究。同时对相关材料和结构的Raman光谱研究作了一些展望。     

助剂对Ni/γ-Al2O3催化剂上多环烃JP-10重整制氢反应性能的影响

采用等体积浸渍法制备了碱金属Na、碱土金属Mg以及稀土金属Ce改性的15% Ni-5% M/γ-Al₂O₃镍基负载型催化剂（标记为NMA,M=Na、Mg、Ce）。通过XRD （X射线衍射）、N₂吸附-脱附、H₂-TPR （H₂-程序升温还原）、TEM （透射电镜）、NH₃-TPD （NH₃-程序升温脱附）、TG （热重）和拉曼光谱技术对催化剂的物相、织构、表面性质等进行了表征分析,并在微通道反应器内研究了多环烃挂式四氢双环戊二烯（JP-10）催化重整制氢性能。结果表明,不同助剂的加入均在一定程度上提高了Ni/γ-Al₂O₃（NA）催化剂的活性和抗积碳性能。其中,NNaA催化剂的表面活性镍物种的浓度最高,颗粒尺寸最小,且其表面总酸量较低,在高温重整反应中对活性组分镍的抑制聚集作用最为明显,从而使其获得最佳的改性效果。在常压、750℃、水碳比（S/C）为2.4、重时空速（WHSV）为472 h^-1条件下,NNaA催化剂上JP-10的转化率和H₂选择性分别可达82.9%和73.3%,而积碳量仅为0.53 mg·g_feed^-1。反应后该催化剂的积碳多为丝状碳,而其他催化剂的积碳多为无定形碳。     

Molecular dynamics simulations of A-DNA in bivalent metal ions salt solution

A-form DNA is one of the biologically active double helical structure. The study of A-DNA structure has an extensive application for developing the field of DNA packaging in biotechnology. In aqueous solution, the A-DNA structure will have a free transformation, the A-DNA structure will be translated into B-form structure with the evolution of time, and eventually stabilized in the B-DNA structure. To explore the stability function of the bivalent metal ions on the A-DNA structure, a series of molecular dynamics simulations have been performed on the A-DNA of sequence (CCCGGCCGGG). The results show that bivalent metal ions (Mg²⁺, Zn²⁺, Ca²⁺) generate a great effect on the structural stability of A-DNA in the environment of high concentration. As the interaction between metal ions and electronegative DNA chains, the stability of A-DNA in solution is gradually improved with the increasing solution concentration of ions. In metal salt solution with high concentration, metal ions can be easily distributed in the solvation shells around the phosphate groups and further lead to the formation of shorter and more compact DNA structure. Also, under the condition of the same concentration and valency of the metal ions, the stability of A-DNA structure is different. The calculations indicate that the structure of A-DNA in CaCl₂ solution is less stable than in MgCl₂ and ZnCl₂ solution.