Relativistic Mean Field Study on Halo Structures of Mirror Nuclei

Halo structures of some light mirror nuclei are investigated with the relativistic mean field （RMF） theory. The calculations show that the dispersion of the valence proton is larger than that of the valence neutron in its mirror nucleus, the difference between the root-mean-square （rms） radius of the valence nucleon in each pair of mirror nuclei becomes smaller with the increase of the mass number A, and all the ratios of the rms radius of the valence nucleon to that of the matter in each pair of mirror nuclei decrease almost linearly with the increase of the mass number A.     

Penny-shaped interfacial crack between dissimilar magnetoelectroelastic layers

A penny-shaped interfacial crack between dissimilar magnetoelectroelastic layers subjected to magnetoelectromechanical loads is investigated,where the magnetoelectrically impermeable crack surface condition is adopted. By using Hankel transform technique,the mixed boundary value problem is firstly reduced to a system of singular integral equations,which are further reduced to a system of algebraic equations. The field intensity factors and energy release rate are finally derived. Numerical results elucidate the eects of crack configuration,electric and/or magnetic loads,and material parameters of the magnetoelectroelastic layers on crack propagation and growth. This work should be useful for the design of magnetoelectroelastic composite structures.     

Enantioselective nanofiber-spinning of chiral calixarene receptor with guest

Chiral para-tert-butylcalix[4]arene bearing (S)-alpha-methylbenzylamine groups at lower rim only self-assembles with one of two enantiomers of 2,3-dibenzoyltartaric acid into coiled nanofibers and the coiled nanofibers only stack with the nanofibers having the same handedness to construct bigger ribbon-like fibers bearing porosity.     

MnFeP_(0.45)As_(0.55)材料中的相变研究

利用不同的测量方法,研究了MnFeP1-xAsx(0·32相似文献   

Preparation of a Single Layer of Luminescent Nanocrystalline Si Structures by Laser Irradiation Method

KrF excimer laser annealing on ultrathin hydrogenated amorphous Si films with various initial Si thicknesses is carried out to obtain a single layer of nanocrystalline Si structures. It is found that Si nanograins can be obtained with the area density as high as 10^11 cm^-2 under the irradiation with suitable laser fluence. Raman and planar transmission electron microscopy are used to characterize the formation process of Si nanocrystals from amorphous phase. Moreover, a strong photoluminescence is observed at room temperature from well-relaxed nanocrystalline Si structures.     

OH分子基态(X2Ⅱ)的结构与势能函数

采用密度泛函理论的B3LYP方法和二次组态相互作用(QCISD(T))方法优化计算了OH分子基态(X2Ⅱ)的平衡结构、振动频率和离解能.根据原子分子反应静力学原理,导出了OH分子基态(X2Ⅱ)的合理离解极限,采用最小二乘法拟合Murrell-Sorbie函数得到了相应的势能函数和与该基态相对应的光谱常数(Be,αe,ωe和ωe xe),计算结果与实验数据符合得相当好.     

酮-过氧化氢体系对烯烃的环氧化

过氧化酮是优良的烯烃环氧化试剂,可将烯烃氧化成环氧化物。在这些反应中,所用的氧化剂都是过硫酸氢钾或商品Oxone^[1-6]。用其它氧化剂与酮生成过氧化酮使烯烃环氧化的报道很少^[7,8],只有一例是使用过氧化氢作氧化剂的,但其只研究了一种酮与过氧化氢对烯烃的环氧化^[8]。本文使用价格便宜,且没有污染的过氧化氢取代Oxone,与酮反应形成的过氧化酮使烯烃环氧化,并首次研究了一系列酮化合物与过氧化氢组成的催化体系对烯烃的环氧化反应,考察了各种酮的催化活性。     

微型化频率选择表面的设计研究

利用容性表面与感性表面之间的耦合机理能够制备微型化频率选择表面(MEFSS),周期单元尺寸将不受工作波长限制.为了提高MEFSS角度与极化的稳定性,展宽MEFSS的-3 dB带宽,文章结合传统频率选择表面"Y"形单元,利用"Y"图形构造容性表面的贴片单元与感性表面的网栅单元且以正三角形栅格拓展周期单元,采用矢量模匹配法对MEFSS栅格排布及其他结构参数变化进行精确计算.通过镀膜与光刻技术在0.15 mm厚聚酰亚胺膜两侧制备容性表面、感性表面并利用自由空间法测试.计算与实验结果均表明,采用正三角形栅格排布的MEFSS,-3 dB带宽达到7.6 GHz,不同极化下60°扫描时中心频点稳定在f₀,为MEFSS应用于曲面天线罩时提供理论与实验参考依据. 关键词： 天线罩 微型化频率选择表面 容性表面 感性表面     

多频段十字分形频率选择表面

利用分形单元的自相似性将分形结构应用于频率选择表面(FSS)领域使单屏FSS具有多频谐振的特性,在各波段实现简易、多频带通滤波器的设计.以易加工的十字单元为例,经过递归、迭代产生二阶十字分形单元,给出描述单元几何分布的公式;应用周期矩量法结合Floquet定理及阻抗边界条件得到描述FSS表面电流分布的电场积分方程,对FSS传输特性规律进行数值分析,采用遗传算法对分形单元参数进行全局优化得到了在9.2 GHz和29.4 GHz谐振的单屏FSS设计;最后采用成熟的镀膜、光刻工艺制备十字分形FSS样件并在微波暗 关键词： 频率选择表面(FSS) 分形单元 多频段 周期矩量法(PMoM)     

p层厚度对Si基GaN垂直结构LED出光的影响

利用金属有机化学气相沉积(MOCVD)法在Si衬底上生长了一系列具有不同p层厚度d的InGaN/GaN蓝光LED薄膜并制备成垂直结构发光二极管(VLEDs),研究了 p层厚度即p面金属反射镜与量子阱层的间距对LED出光效率的影响,并采用F-P干涉模型进行了理论分析.结果显示,光提取效率受d影响很大,随d的增加呈现类似阻...