基于双核模型对准裂变产物质量分布的研究

在双核模型基础上引入一维的Kramers公式，计算了⁴⁸Ca+²⁴⁴Pu，⁴⁸Ca+²³⁸U和⁵⁸Fe+²³²Th这三个反应准裂变碎片的质量分布，得到了与实验比较符合的结果.同时提取出了碎片质量分布随时间的演化关系，为理解熔合与准裂变竞争过程提供了非常有用的信息.由于准裂变在重离子熔合反应中起着重要作用，理论计算与实验结果的比较是对现有熔合模型的重要检验. 关键词： 超重元素 熔合反应 准裂变产物 质量产额     

15——20mA负氢离子源的设计与加工

离子源是强流质子回旋加速器的核心设备之一,它的性能指标对最终束流大小和质量都有重大影响.文章介绍了一种运用于强流质子回旋加速器上的多峰场负氢离子源的设计与加工情况,该离子源主要是通过深入研究高密度等离子体产生技术、长寿命大直流灯丝电子发射技术、磁约束技术、虚拟过虑技术、残留气体与电子剥离的控制技术,以及离子引出技术等,在中国原子能科学研究院原有10mA离子源基础上建立负氢离子源,实验研究低能、强流束的实验匹配与调试技术,将平均引出柬流提高到15-20mA.     

新型四硫富瓦烯-杯芳烃衍生物的合成与其电化学行为

在高度稀释条件下, 溴烷基化杯[4]芳烃1a和1b分别与二-(1,3-二硫杂环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐在乙腈中回流, 得到含杯[4]芳烃单元的硫酮2a和2b. 以亚磷酸三乙酯为偶联剂, 其分别和4,5-二腈基乙硫基-1,3-二硫代环戊烯-2-酮发生交叉偶合反应, 合成了两个新颖的四硫富瓦烯–杯[4]芳烃衍生物3a和3b, 并对其进行了结构表征和电化学行为研究. 同时用X射线衍射法确认了2b的晶体结构.     

Modification and stabilizing effects of PEG on resveratrol-loaded solid lipid nanoparticles

Resveratrol-loaded solid lipid nanoparticles (SLNs) modified by polyethylene glycol (PEG2000) (RES–PEG–SLNs) were prepared to study the stabilizing influences of PEG2000 on SLNs properties including loading capacity, particle size, photostability, and release. The micromorphology, particle size distribution, drug–lipid–modifier interaction and crystalline structure were characterized to elucidate stabilizing effects of PEG2000 on SLNs. Compared with ordinary SLNs, SLNs modified by PEG2000 at relatively low amounts of [m(PEG2000):m(lipids) = 1:10] exhibit high drug loading, steady nanoparticle size distributions, photostability and sustained release. According to characterizations, RES–PEG–SLNs formation is dependent on the physical interactions of drug–lipid–modifier. Since PEG2000 is doped into lipid matrix in a non-crystalline state, the lipids crystalline arrangement is disrupted. Additionally, RES–PEG–SLNs are crystallized in a PEG2000/lipid eutectic mixture rather than a simple mixture, inhibiting the lipid polymorphism transformation from α- to β-form, and therefore preventing drug exclusion from the lipid matrix. The PEG2000/lipid matrix contains lattice defects, which allow for the incorporation of more resveratrol and preventing it from photodegradation effectively. In contrast to the burst release of SLNs modified without PEG2000, resveratrol is released more slowly from the lattice defects in lipid matrix of RES–PEG–SLNs, resulting in a sustained release fitted by a two-stage exponential kinetic equation. PEG2000 is distributed on the RES–PEG–SLNs surface, increasing repulsion between nanoparticles and avoiding particles aggregation. These results confirm that both matrix doping effects and surface steric hindrance produced by the presence of PEG2000 play important roles in maintaining high loadings, nanoparticle size, photostability and sustained release.     

Spin Coulomb Dragging Inhibition of Spin-Polarized Electric Current Injecting into Organic Semiconductors

We introduce a one-dimensional spin injection structure comprising a ferromagnetic metal and a nondegenerate organic semiconductor to model electric current polarizations. With this model we analyse spin Coulomb dragging (SCD) effects on the polarization under various electric fields, interface and conductivity conditions. The results show that the SCD inhibits the current polarization. Thus the SCD inhibition should be well considered for accurate evaluation of current polarization in the design of organic spin devices.     

纳米铋酸钠的合成及其结构表征

采用次氯酸钠浓溶液在强搅拌条件下和强碱性环境中氧化硝酸铋,得到纳米铋酸钠晶体.研究结果表明,反应过程中的中间产物氢氧化铋的粒度及分散性能是影响铋酸钠制品的粒度及分散性能的关键因素.研究了次氯酸钠浓度、硝酸铋浓度和反应时间对纳米铋酸钠制品的粒度和纯度的影响,得出了最佳的合成条件.采用化学分析、TEM、IR、TG-DSC和XRD等测试手段证实样品的化学组成为NaBiO₃·2H₂O,是粒径为30～50nm的纳米级鳞片状晶体.     

致密天体中电子气体对原子核结构的影响

运用相对论平均场理论结合Wigner-Seitz近似,研究了致密物质中电子气体对⁵⁶Fe和¹²⁰Sr结构的影响,对关联的处理采用Bardeen-Cooper-Schrieffer方法.结果表明电子气体对单粒子能级、核子密度分布、核子分布均方根半径、原子核均方根半径等性质都有影响,并且对质子的影响大于对中子的影响. 关键词： 相对论平均场理论 Wigner-Seitz近似 单粒子能级 均方根半径     

Spin-Polarized Carriers Injection from Ferromagnetic Metal into Organic Semiconductor

Charge carriers in organic semiconductor are different from that oftraditional inorganic semiconductor. Based on three-current model,considering electrical field effect, we present a theoretical model todiscuss spin-polarized injection from ferromagnetic electrode into organicsemiconductor by analyzing electrochemical potential both in ferromagneticelectrode and organic semiconductors. The calculated result of this modelshows effects of electrode's spin polarization, equilibrium value ofpolarons ratio, interfacial conductance, bulk conductivity of materials andelectrical field. It is found that we could get decent spin polarizationwith common ferromagnetic electrode by increasing equilibrium value ofpolarons ratio. We also find that large and matched bulk conductivity oforganic semiconductor and electrode, small spin-dependent interfacialconductance, and enough large electrical field are critical factors forincreasing spin polarization.     

聚合物多元醇分散体的流变特性

聚合物多元醇分散体(以下简称分散体)是接枝聚醚多元醇、聚醚多元醇和乙烯基单体聚合物的混合物,直接用于制备高回弹、高负载和阻燃的软质和半软质聚氨酯泡沫体,是新一代聚醚多元醇产品[1].分散体用于聚氨酯工业中各种产品的生产,除要求有良好的稳定性外,其最为重要的指标是粘度应小于3000mPa·s和乙烯基单体聚合物的含量(固含量)应大于40%.但分散体的粘度,随固含量的增加呈指数性增加[2].近年来,已有既具高固含量和良好稳定性,又有较低粘度的分散体的研究报道[3].本文在不同的反应条件下,合成了分散体,测定了其流变特性和体系中微粒的大小…     

THE CHARGE RELAXATION PROCESS IN THE DISSIPATIVE HEAVY-ION COLLISIONS OF THE MASS ASYMMETRY SYSTEM

The variances and mean values of the charge distributions in the dissipative heavy-ion collisions of mass asymmetry system have been calculated by use of the dissipative dynamics equation coupling with the master equation.There is a nice agreement between experimental values and calculated results.