~(143)Dy和~(141)Dy的β缓发质子衰变与自旋指认

分析了143Dy和141Dy的β缓发质子衰变的数据,对比计算了这两种核的核位能面。从中看到了143Dy的衰变包括有1/2+基态和11/2-同核异能态的两种衰变成分,并且确定了它们的半衰期分别为(6.0±1.5)s和(3.0±0.5)s。同时也测定了141Dy的半衰期为(0.9±0.2)s,并指认了它的自旋宇称为9/2-。

~(140)Tb和~(141)Dy的β缓发质子衰变以及~(143)Dy的自旋宇称

利用40Ca+106Cd融合蒸发反应产生了近质子滴线核140Tb和141Dy,配合氦喷嘴带传输系统采用“质子-γ”符合方法观测了它们的β缓发质子衰变,其中包括半衰期、质子能谱和衰变到第二代子核不同低位态的分支比．通过统计理论拟合提取了140Tb和141Dy的基态自旋宇称分别为7±和9／2±．另一方面,用Woods-Saxon Strutinsky方法计算了这两种核限制组态的势能面,由此得到140Tb和141Dy的基态自旋宇称分别为7+和9／2-．此外用同一方法还计算了143Dy的核势能面,从中看出143Dy存在有自旋宇称为1／2+的基态和一个激发能为198keV的11／2-的同质异能态．该结果与2003年Eur．Phys．J． A16:347-351中的143Dy衰变实验数据相符．

~(141)Nd激发态的在束γ谱学研究

通过1 3 0 Te(1 6O ,5nγ) 1 4 1 Nd反应布居了1 4 1 Nd的高自旋态能级 .对反应产生的在束γ射线进行了γ射线单谱和γ -γ符合测量 .建立了激发能达 76 1 4 .5keV的1 4 1 Nd能级纲图 ,新发现了 1 2条γ射线和 1 5个能级 .基于实验测量的γ跃迁各向异性 ,建议了1 4 1 Nd部分能级的自旋值 .用一个h1 1 2 价中子空穴与1 4 2 Nd核芯晕态的耦合可以定性地解释1 4 1 Nd的能级结构

~(141)Nd中的粒子-核芯耦合

通过~(130)Te(~(16)O,5nγ)~(141)Nd反应研究了~(141)Nd的高自旋态。建立了激发能达7614.5keV的~(141)Nd能级纲图,新发现了12条γ射线和15个能级。用粒子-振子模型和半经验壳模型分别计算了~(141)Nd的集体和单粒子激发的能级位置。根据计算的能级位置以及实验测量得到的γ跃迁强度和多极性信息,讨论了~(141)Nd激发态的能级结构。

beta-delayed proton decays and spin assignments for Tb-140, Dy-141 and Dy-143

The proton-rich isotopes Tb-140 and Dy-141 were produced via the fusion evaporation reaction Ca-40+ Cd-106. Their beta-delayed proton decays were studied by p-gamma coincidence in combination with a He-jet tape transport system, and half-lives, proton energy spectra, gamma-transitions following the proton emission, as well as beta-delayed proton branching ratios to the low-lying states in the grand-daughter nuclei were determined. Comparing the experimental data with statistical model calculations, the ground-state spins of Tb-140 and Dy-141 were found to be consistent with 7 and 9/2, respectively. The configuration-constrained nuclear potential energy surfaces (NPES) of Tb-140 and Dy-141 were calculated using the Woods-Saxon-Strutinsky method, which suggest the ground-state spins and parities of Tb-140 and Dy-141 to be 7(+) and 9/2(-), respectively. In addition, the configuration-constrained NPES of Dy-143 were calculated, which predict a 1/2(+) ground state and a 11/2(-) isomer with excitation energy of 198 keV. These findings are consistent with our previous experimental data on Dy-143 reported in Eur. Phys. J. A 16, 347 (2003).

Material response and failure mechanism of unidirectional metal matrix composites under impulsive shear loading

The material response and failure mechanism of unidirectional metal matrix composite under impulsive shear loading are investigated in this paper. Both experimental and analytical studies were performed. The shear strength of unidirectional C-f/A356.0 composite and A356.0 aluminum alloy at high strain rate were measured with a modified split Hopkinson torsional bar technique. The results indicated that the carbon fibers did not improve the shear strength of aluminum matrix if the fiber orientation aligned with the shear loading axis. The microscopic inspection of the fractured surface showed a multi-scale zigzag feature which implied a complicated shear failure mechanism in the composite. In addition to testing, the micromechanical stress field in the composite was analyzed by the generalized Eshelby equivalent method (GEEM). The influence of cracking in matrix on the micromechanical stress field was investigated as well. The results showed that the stress distribution in the composite is quite nonhomogeneous and very high shear stress concentrations are found in some regions in the matrix. The high shear stress concentration in the matrix induces tensile cracking at 45 degrees to the shear direction. This in turn aggravates the stress concentration at the fiber/matrix interface and finally leads to a catastrophic failure in the composite. From the correlation between the analysis and experimental results, the shear failure mechanism of unidirectional C-f/A356.0 composite can be elucidated qualitatively.

抗癌药长春新碱及其与微管蛋白相互作用的电化学研究

在0.05 mol/L Tris，0.15 mol/L NaCl溶液中，用吸附伏安法研究长春新碱(VCR)，其峰电位在-1.68 V(vs. Ag/AgCl)，峰电流与1.0*10^{-8}～2.0*10^{-7}mol/L VCR浓度成正比，检测限为7.0*l0^{-9} mol/L，用常规脉冲极谱法、线性扫描和循环伏安法等研究该体系的电化学行为，实验表明，电极还原过程为具有吸附特征的不可逆过程。VCR的吸附符合Frumkin吸附等温式。也研究了VCR与微管蛋白的相互作用。实验表明，VCR与微管蛋白形成一电活性的结合物，这一结合物具有吸附性，且还原过程也为不可逆过程。

二元体系胶体晶体性质的实验研究

利用Kossel衍射技术和反射光谱对由总体积分数为0.02的二元聚苯乙烯胶体体系(94 nm+141 nm)形成的胶体晶体的性质进行了研究,实验结果显示胶体晶体的形成时间,平均粒子间距,晶体结构都与二元胶体体系中两种粒子的数密度比相关,当94 nm聚苯乙烯粒子相对于141 nm聚苯乙烯粒子的数密度比趋向1∶1时,胶体晶体的形成时间延长,当94 nm聚苯乙烯粒子相对于141 nm聚苯乙烯粒子的数密度比由1∶0向0∶1变化时,胶体晶体的平均粒子间距变大,另外实验中发现在两种粒子的数密度比为5∶1时,胶体晶体出现了超晶格结构. 

Modified Generalized Beam Lattice Model Associated With Fracture Of Reinforced Fiber/Particle Composites

Lattice-type model can simulate in a straightforward manner heterogeneous brittle media. Mohr-Coulomb failure criterion has recently been involved into the generalized beam (GB) lattice model, and as a result, numerical experiments on concrete under various loading conditions can be conducted. The GB lattice model is further used to investigate the reinforced fiber/particle composites instead of only particle composites as the model did before. Numerical examples are given to show the effectiveness of the modeling procedure, and influences of inclusions (particle, fiber and rebar) on the fracture processes are also discussed. (c) 2008 Elsevier Ltd. All rights reserved.

Characterization Of Crystal Structure In Binary Mixtures Of Latex Globules

Colloidal crystals formed by two types of polystyrene particles of different sizes (94 and 141 nm) at various number ratios (94:141 nm) are studied. Experiments showed that the formation time of crystals lengthens as the number ratio of the two components approaches 1:1. The dependence of the mean interparticle distance (D-0), crystal structure and alloy structure on the number ratio of the two types of particles was Studied by means of Kossel diffraction technique and reflection spectra. The results showed that as the number ratio decreased, the mean interparticle distance (D-0) became larger. And the colloidal crystal in binary mixtures is more preferably to form the bcc structure. This study found that binary systems form the substitutional solid solution (sss)-type alloy structure in all cases except when the number ratio of two types of particles is 5:1, which results instead in the superlattice structure. (C) 2008 Elsevier Inc. All rights reserved.

受拉铝板对连续波CO_2激光的热机械响应

本文对受拉伸载荷的铝合金板被强连续波CO_2激光照射时的热机械响应进行了报导。介绍联合加载实验装置,实验方法和实验结果。对试件的断裂过程以及断裂前的应力应变分布进行了讨论。