通过平均场处理的严格重正化群变换方法对Potts模型的应用

本文运用作者所发展的严格docimation- 平均场近似方法对Potts 模型的临界指数作了计算.所得结果与严格解符合得很好, 而与计算工作量相当的重正化群方法相比, 精确度大为提高。 关键词：     

二维混合区域的中子碰撞概率的计算

本文对由长方形或三角形栅元组成的反应堆栅格,从碰撞概率定义出发,建立了二维多体系统的中子首次碰撞概率计算的公式,并将计算结果与蒙特卡洛方法的计算结果进行了比较。     

5,10,15,20—四(4-甲氧基-3-磺酸苯基)卟啉光度法测定痕量铜的研究

5,10,15,20-四(4-甲氧基-3-磺酸苯基)卟啉[T(4-MOP)PS_4]是一种新的水溶性卟啉显色剂.它与铜反应的最适pH=3.2,配合物的最大吸收波长为416.3um,配位比为1:1,摩尔吸光系数为 3.18×10~5 L·mol~(-1)·cm~(-1).显色后用0.10mol/LHC12.0ml酸化..该试剂具有灵剂度高选择性好的特点,无需加任何掩蔽剂可成功地用于头发和大米中痕量铜的测定,所得结果与原子吸收光度法很一致.方法的测定范围是0-3.5ugCu~(2+)/25m1.相关系数r=0.9991.     

离散可激发介质中早期后去极化对螺旋波影响的数值研究

通过考虑某些不应态也可以被激发,在离散可激发介质Greenberg-Hasting模型中引入早期后去极化行为,研究了早期后去极化对螺旋波的影响.数值结果表明:在适当选择参数下,早期后去极化对螺旋波有很大影响,这些影响包括使螺旋波漫游、漂移和破碎,导致螺旋波波纹被扭曲和波臂粗细交替变化,以及导致螺旋波的周期在两个值之间交替变化,产生从稳定螺旋波到呼吸螺旋波和反螺旋波的相变等.当不应态的激发阈值很高时,早期后去极化对螺旋波没有影响.对发生上述现象作了简要的讨论. 关键词： 离散可激发介质 螺旋波 早期后去极化     

Structures of Pt clusters on graphene doped with nitrogen, boron, and silicon: a theoretical study

The structures of Pt clusters on nitrogen-,boron-,silicon-doped graphenes are theoretically studied using densityfunctional theory.These dopants(nitrogen,boron and silicon) each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form.The formation energy of the silicon-graphene system is lower than those of the nitrogen-,boron-doped graphenes,indicating that the silicon atom is easier to incorporate into the graphene.All the substitutional impurities enhance the interaction between the Pt atom and the graphene.The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen-and boron-doped graphenes.The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size.The stable structures of Pt clusters on the doped-graphenes are dimeric,triangle and tetrahedron with the increase of the Pt coverage.Of all the studied structures,the tetrahedron is the most stable cluster which has the least influence on the planar surface of doped-graphene.     

实际量子密钥分配扩展BB84协议窃听下的安全性分析

考虑强衰减激光脉冲技术实现的准单光子源和量子信道损耗以及窃听者Eve窃听能力有限等实际情况, 提出了一种窃听装置;同时对扩展BB84协议的各种窃听做了全面分析,计算得出发送者Alice/窃听者Eve所获得的交互信息量和发送者Alice/接收者Bob所能容忍的误码率上限,以此作为检测量子信道安全性的标准,同时得出Breidbart基/分束攻击相结合的方法是比截取/重发更为有效的窃听方案.     

On the Formation of Nanostructures from Stilbazolium-like Dyes

Nanostructures with well-defined shape and highly monodisperse size were fabricated from model stilbazolium-like dyes with specific molecular structural and conformational characteristics. With the help of absorption and fluorescence optical spectroscopy, the correlated spectroscopy (COSY) and two- dimensional nuclear Overhauser effect spectroscopy (2D NOESY) techniques, along with X-ray diffraction (XRD) measurement, distinctively different aggregation processes of the model molecules are demonstrated. For model dye molecule with linear donor–π system–acceptor (D–π–A) structure, strong D–A pair, and planar conformation, specific intermolecular interaction was identified and special crystal structures as well as spectral properties were observed. For model dye molecules bearing nonlinear D–π–A–π–D structure, weak D–A pair but actual amphiphilic characteristics, a special aggregation process was confirmed and a focused size distribution of the produced nanostructures was obtained.     

Microelectromagnet for magnetic manipulation in lab-on-a-chip systems

We demonstrate a simple scheme for fabrication of microelectromagnets consisting of planar spiral coils semi-encapsulated in soft magnetic yokes using conventional microfabrication techniques. The microelectromagnets are suitable for applications operating at frequencies below 250 kHz. Conventional fabrication schemes for planar microelectromagnets typically rely on five mask steps. We allow the current to flow in the soft magnetic yoke and thereby two mask steps are eliminated. We have characterized the electromagnets electrically, the results agree well with theory, and the implications arising from current flowing in the magnetic yoke are discussed. We have integrated the microelectromagnets with microfluidic channels, and demonstrated separation of commercially available magnetic beads from a fluid in a microfluidic system, i.e. a lab-on-a-chip system.     

C72,La2@C72几何结构和电子性质的计算研究

采用密度泛涵理论(density functional theory,DFT)中的广义梯度近似(generally gradient approximation,GGA)对富勒烯C72和内掺金属La富勒烯La2@C72三种同分异构体的几何结构和电子结构进行研究.发现在C72的三种同分异构体中,满足独立五边形规则(isolated-pentagon-rule,IPR)的C72(D6d)结构最为稳定;在La2@C72三种同分异构体中,有着两对两两相邻五元环(twofused-pentagon)的La2@C72(#10611)结构最为稳定,而满足IPR的La2@C72(D6d)的结构变成了最不稳定结构.从能级图和态密度图分析得知,笼子稳定性的变化与La原子的原子轨道与C72原子轨道之间的杂化有关.Mulliken电荷分析得知,La2@C72(#10611)的两个La原子共转移了约3个电子给C72,并且,它们几乎分布在整个C笼上,形成的电子结构为La23+@C3-72.净自旋分析得知,La2@C72(#10611)中La原子磁性完全淬灭.     

过量Zn对β-Zn4Sb3热电性能影响的研究

采用真空熔融缓冷方法制备了单相β-Zn4Sb3以及含有过量Zn的β-Zn4Sb3块体热电材料.在300—700K的温度范围内测试了材料的电导率、Seebeck系数和热导率,研究了β-Zn4Sb3化合物中过量Zn的分布状态及其对材料热电性能的影响规律.结果表明：过量的Zn作为第二相较均匀的分布在β-Zn4Sb3的晶界上,随着Zn含量增加,材料电导率和热导率上升,Seebeck系数下降,Zn第二相的引入能有效提高材料的功率因子,Zn过量2at%的材料在700K时其ZT值达到1.10.