兰州重离子加速器冷却储存环中电子冷却性能

为了在兰州重离子加速器冷却储存环(HIRFL-CSR)上开展一维离子束序化的研究,在CSR主环上,对6.39 MeV/u的58Ni19+离子束进行了冷却累积实验。测量了离子束与电子束之间不同的水平、垂直夹角以及不同电子束剖面的情况下,束流累积及束流寿命变化情况;重点研究了离子束衰减过程中动量分散随离子数的变化规律,拟合计算得到了动量分散随离子数按照幂函数衰减的指数;在给定离子数的情况下,动量分散随夹角、电子束剖面的依赖关系,为下一步在CSR上获得纵向一维有序化离子束的研究做准备。在实验中观测到在较大的夹角情况下,离子束出现纵向振荡和中心频率移动。     

Design of shaped piezoelectric modal sensors for cantilever beams with intermediate support by using differential transformation method

In this paper a solution to the problem of finding the shape of piezoelectric modal sensors for a cantilever beam with intermediate support is proposed by using the differential transformation method (DTM). A general expression for designing the shape of a piezoelectric modal sensor is presented, in which the output signal of the designed sensor is proportional to the response of the target mode. Other modes are filtered out. The modal sensor shape is expressed as a linear function of the second spatial derivative of the structural mode shape function. By using boundary condition and continuity condition equations at intermediate support, the closed-form series solution of the second spatial derivative of the mode shapes can be determined based on DTM. Then the shapes of the designed modal sensors are obtained. Finally, numerical examples are given to demonstrate the feasibility of the proposed modal sensors for the cantilever beam with intermediate support.     

Superhydrophobic nickel films fabricated by electro and electroless deposition

In this work, a superhydrophobic nickel surface is fabricated by coupling electro and electroless deposition without chemical modification. SEM study reveals that electrodeposited nickel surface is characterized by nanocone arrays and has a contact angle of about 135°. After adding electroless deposition, as the second step, hemispherically topped nickel nanocone arrays are formed which leads to a high contact angle of 153.6°. That is, nickel surface has successfully transformed from hydrophobic to superhydrophobic. This transition is investigated both from the aspects of chemical composition and surface structure and proves the latter is the dominant factor. The present study inspires us to do more research about the creation of rough surfaces and enriches our comprehension about superhydrophobicity.     

The doping effects of BiFe1-xCoxO3 （x=0.0-0.8） in layered perovskite BiaTi3O12 ceramics

BisFe1-xCoxTi3O15 （x=0.0, 0.2, 0.4, 0.5, 0.6, and 0.8） multiferroic ceramics are synthesized in two steps using the solid state reaction technique. X-ray diffraction patterns show that the samples have four-layer Aurivillius phases. At room temperature （RT）, the samples each present a remarkable coexistence of ferromagnetism （FM） and ferroelectricity （FE）. The remnant polarization （2Pr） reaches its greatest value of 14 gC/cm2 at x = 0.6. Remnant magnetization （2Mr） first increases and then decreases, and the greatest 2Mr is 7.8 menu/g when x = 0.5. The magnetic properties for x = 0.4 are similar to those for x = 0.6, indicating that the magnetic properties originate mainly from the coupling between Fe3＋ and Co3＋ ions, rather than from their own magnetic moments.     

用杂化CIS-DFT方法研究外电场对乙烯激发态的影响

采用杂化CIS-DFT方法研究了外电场对乙烯分子基态和激发态性质的影响，结果表明外电场对分子几何结构，总能量，偶极矩，极化率，振子强度和激发能有显著影响。CIS-DFT的优点在于它能确定外场下分子的对称性并且给出正确的激发顺序以及分子轨道的电子组态，由此导出乙烯分子的激发态，计算结果与实验一致。首次研究了乙烯分子的外电场效应。与其他从头算方法相比，杂化CIS-DFT方法计算精度和效率相对较高，可用于研究大分子体系。     

小试金富集ICP-AES法同时测定试样中的铂、钯、金

文章报道了用小试金富集ICP AES法同时测定试样中的铂、钯和金 ,将 1 0～ 2 0g试样中的铂、钯、金富集在毫克量的银合粒中 ,制成溶液后用ICP AES法同时测定铂、钯和金。该方法的检出限 (μg·mL-1 )Pt,Pd ,Au分别为 0 0 1 ,0 0 0 5 ,0 0 1 ,相对标准偏差 (RSD ,n =1 0 )分别为 0 1 % ,0 1 2 % ,0 0 9% ,标准回收率均在 97%以上。生产实践表明 ,本方法是一种快速、简便、准确的分析方法 ,已被我们应用于测定样品中的铂 ,钯和金     

超导体Bi1.8Pb0.2Sr2-xLaxCuOy的电阻率和热电势研究

本文对名义组份为Bi1.8Pb0.2Sr2-xLaxCuOy系列样品的电阻率和热电势特性进行了实验研究.测量表明,Pb掺杂可以进一步提高超导转变温度Tc ;随着La含量的增加,Tc 按照典型的抛物线型规律变化;La掺杂极大地影响超导体正常态的输运特性.我们的分析指出,热电势在正常态所表现出的规律与高温超导机制密切相关,而且电阻率正常态输运特性的变化可用La掺杂造成CuO6八面体顶点氧发生位移来解释.     

激光拉曼光谱在玉石鉴定中的应用

本文提出玉石品种鉴定的新方法———激光拉曼光谱法。测试了一系列玉石的标准拉曼谱     

超高能γ–强子族的能量集中现象

通过对甘巴拉山铁乳胶室观测到的族事例以及COSMOS程序和CORSI-KA程序产生的模拟族事例进行分析、对比,对超高能γ强子族的能量集中现象的产生特征进行了细致的研究.初步的结论是:超高能γ强子族的能量集中现象是族中含有的高能中心簇射集团的外在表现,这种现象在实验上发生的频度为(20.5±3.1)%,集团的平均横向扩展约为0.37cm.与传统的以唯象多团模型为基础的COSMOS程序相比,基于SIBYLL模型的CORSIKA程序的模拟结果较为接近实验的分析结果.     

Cyclotron resonance and effective mass renormalizations in Sr2RuO4

Using a microwave cavity perturbation technique, we have succeeded in observing cyclotron resonances in the layered Perovskite superconductor Sr₂RuO₄. Three cyclotron masses are deduced, corresponding to m_cγ=9.7m_e, m_cβ=5.8m_e and m_c=4.3 m_e. A comparison between these values and the effective masses deduced from other techniques provides us with a unique means of gauging the role of Coulomb correlations in the title compound.