PVC氯化原位接枝BA的合成与表征

采用气-固相搅拌式方法,氯气作为引发剂,在加热的情况下合成了聚氯乙烯(PVC)、丙烯酸丁酯(BA)的氯化原位接枝共聚产物(CPVC-g-BA)。用IR、1H-RNM等分析手段研究了PVC氯化原位接枝BA反应的可行性,以GPC等数据讨论了接枝共聚物的结构,并考察了反应温度、反应时间、单体用量对产物接枝率的影响:当加入20份BA,反应温度为120℃时,反应100 m in,接枝率达1.07%。     

冲击波压力和脉冲持续时间对铁和镍微结构的影响

用一级轻气炮对铁和镍两种材料动态加载。用透射电镜观察两种材料的位错结构。结果发现：受动加载作用后铁和镍的位错结构分别是类似于网状的和网状的结构。冲击波压力与位错密度有直接关系，而在本试验的条件下脉冲持续时间对位错密度没有影响。     

北京大学6MV串列静电加速器的运行及其应用

北京大学６ＭＶ串列静电加速器上建成４条束流输运线，加速＾１Ｈ，＾１２Ｃ，＾１６Ｏ，＾１９Ｆ，＾３５Ｃｌ，＾７９Ｂｒ等离子，并开展物理实验研究。首次利用Ｄ（＾１２Ｃ，ｐ）＾１３Ｃ核反应建立起高灵敏度的氘分析法；利用共振核反应＾１Ｈ（＾１９Ｆ，αγ）＾１６Ｏ分析材料中氢的深度分布；用重离子背散射分析超导材料ＹＢａ２Ｃｕ３Ｏ７－ｘ；用３５ＭｅＶ＾３５Ｃｌ和４５ＭｅＶ＾７９Ｂｒ的弹性前冲分析不同材料中的轻     

Correlation of the Mechanical Properties of Polycrystalline Ni_3Al Alloys with Their Electronic Structure

The electronic structure of Ni_3Al alloys with different B contents has been investigated by measuringthe positron lifetime spectra.The segregation of B atoms to defects could form strong covalentbondings with Ni and Al atoms and make the electronic structure in those locations similar to that inbulk,thus strengthen their cohesion.The interaction of B atoms,which were solid-solutioned in thecrystal lattice of Ni_3Al in a manner of occupying interstitial sites,with Ni and Al atoms resulted in theincrease of the density of valent electrons,thus increased the bonding cohesion in bulk.The im-provement of the mechanical properties of Ni_3Al alloys by B doping was due to both“grain bounda-ry effect”and“bulk effect”of B,which correlated with their electronic structure.     

掺铕稀土配合物的光学树脂荧光光谱研究

报道了将多种稀土铕配合物复合于苯乙烯(ST)／甲基丙烯酸(HMA)的共聚体系,研究了含稀土配合物透明光学树脂的光学性能。发现其具有发光效率高,光谱呈现尖锐的线状谱带及相对于纯稀土配合物粉末来说掺有稀土配合物的光学树脂的发射产生光谱红移等特点。特别是用电子云重排效应(当中心稀土离子与不同配体结合时,其相同的J能级间的跃迁谱带位置略有移动的现象)解释了掺有稀土配合物的光学树脂发射光谱红移现象。并推断出在含稀土配合物复合于光学树脂后。稀土中心离子和配位原子间距离有所减小。     

MgO∶LiNbO_3晶体中超短中红外非共线相位匹配光参量放大过程角度的优化选择

计算了MgO∶LiNbO3中超短中红外光参量放大(OPA)过程中晶体的相位匹配角与非共线角的优化选择。结果表明,对于800nm波长的抽运光,信号光波长为1053nm时,非共线角α优化在1.74°~2°之间;当信号光波长在1046~1067nm内变化时,α在1.05°~2.18°之间,并且当信号光波长为1057nm,α=1.76°时,可实现三波间群速度的完全匹配。同时还得到了抽运光中心波长在780~810nm之间变化时,实现完全群速度匹配时的注入信号光波长与对应的中红外光以及相应的非共线角与相位匹配角。     

Bulk metallic glasses formed by alloying the Cu_6Zr_5 cluster

The bulk metallic glass formation in the Cu-Zr-M ternary systems by alloying of a binary basic Cu6Zr5 cluster was inves- tigated, where M stands for Sn, Mo, Ta, Nb, Ag, Al and Ti. The Cu6Zr5 cluster is a capped Archimedean antiprism that characterizes the local structure of the Cu10Zr7 crystalline phase. This cluster composition almost superposes with Cu-Zr eutectic Cu0.56Zr0.44. A se- ries of alloys along the cluster line (Cu6Zr5)1-xMx were examined for their glass forming abilities. Alloy rods with a diameter of 3 mm were prepared by copper mould suction casting method and analyzed by XRD and thermal analysis. The Cu-Zr based bulk metallic glasses were discovered with minor Nb, Sn, Mo, Ta additions (≤2at%) and Al, Ti, Ag (8at%≤concentration≤9at%). The alloying mechanism was discussed in the light of atomic size, cluster-linking structure and electron concentration factors.     

Numerical simulation of magnetospheric ULF waves excited by positive and negative impulses of solar wind dynamic pressure

The sources of ultra low frequency (ULF) waves in the magnetosphere are generally believed to be either the external solar wind perturbations or the internal plasma instabilities. When a sudden impulse of the solar wind dynamic pressure impinges on the magnetopause, ULF waves might be excited and thus the solar wind energy is transported into the earth’s magnetosphere. In this paper, we study the ULF waves excited by different kinds of sudden solar wind pressure impulses through an MHD simulation. We primar...     

电子的纵向极化和粒子的电荷二旋量理论

本文通过对电子的纵向极化的分析,导出了轻子和光子的电荷二旋量公式,并把它推广到全部粒子领域,从而建立了电荷的二旋量理论。     

Discovery and Research of High Tc Superconductor in the Institute of Physics, Academia Sinica

1. Introduction The discovery of possible high T_C super-conductivity at 35K in La-Ba-Cu-O systemsparked an intense study on the new classof cupric oxides by a few laboratoriesincluding the joint research group of highT_C superconductivity in the Institute ofPhysics, Academia Sinica. A few monthslater we not only confirmed the