γ-羟基丁烯羟酸内酯类内皮激素拮抗剂的比较分子场分析

采用比较分子场分析方法（CoMFA)分析了一组γ-羟基丁烯羟酸内酯类内皮激素拮抗剂的活性与结构的关系。在计算中,除了考察立体场和静电场,还引入了氢键场,结果表明,引入氢键场可以明显改善计算的结果。所得模型不仅能够很好地预测训练集中的分子,而且还可准确地预测测试集中的化合物。通过分析分子场等值面图在空间的分布,可以观察到叠合分子周围的立体、静电以及氢键特征对化合物活性的影响。     

Controlling growth of aligned carbon nanotubes from porous silicon templates

Fabricating well-aligned carbon nanotubes, especially, on a silicon substrate is very important for their applications. In this paper, an aligned carbon nanotube array has been prepared by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles embedded in porous silicon (PS) templates. High-magnification transmission electron microscopy images confirm that the nanotubes are well graphitized. The PS substrates with pore sizes between 10 and 100 nm play a control role on the growth of carbon nanotubes and the diameters of the tubes increase with the enlargement of the pores of the substrates. However, such a control role cannot be found in the macro-PS substrates.     

拉格朗日-欧拉方法模拟高分子复杂流体平面绕流

为验证拉格朗日 欧拉方法的准确性 ,对高分子溶液的 2∶1绕圆柱流动问题进行了数值模拟 ,采用单松弛时间的PhanThien Tanner本构方程 ,得到PIB/C14溶液在De =0 93的绕流计算结果 ,同Baaijens等所做的绕流实验中的稳态流场物理量的测量结果进行了比较 ,在定量上取得较好的一致性 .证明拉格朗日 欧拉方法能够在定性上乃至在定量上准确地预报高分子复杂流体的流动行为 ,在描述真实的物理过程时是合理、准确的     

Quantum circuits for realizing deterministic and exact teleportation via two partially entangled pairs of particles

Deterministic and exact teleportation can be achieved via two partially entangled pairs of particles [Gu Y J 2006 {\em Opt. Comm.} {\bf 259} 385]. The key point of the protocol is a generalized measurement described by a positive operator-valued measure, which can be realized by performing a unitary operation in the extended space and a conventional Von Neumann orthogonal measurement. By decomposing the evolution process from the initial state to the final state, we construct the quantum circuits for realizing the unitary operation with quantum Toffoli gates, and thus provide a physical means to realize the teleportation. Our method for constructing quantum circuits differs from the usual methods based on decomposition of unitary matrices, and is convenient for a large class of quantum processes involving generalized measurements.     

PPEGMEA-g-PDEAEMA全亲水接枝共聚物的合成及其 包埋甲氨喋呤体外控释的研究

以聚乙二醇丙烯酸酯(PEGMEA)为起始原料, 将原子转移自由基聚合(ATRP)技术和从主干接枝(grafting-from)策略相结合, 合成了结构规整的聚甲基醚聚乙二醇丙烯酸酯-g-聚(N,N’-二乙基胺乙基甲基丙烯酸酯) (PPEGMEA-g- PDEAEMA)接枝共聚物. 这种接枝共聚物通过静电作用形成胶束包埋甲氨喋呤(MTX), 得到具有98.7%高包封率的药物载体, 体外药物释放得到很好的控制.     

Sm金属富勒烯的高效提取和电化学性质研究

在金属富勒烯 [1]的形成过程中 ,存在从金属到碳笼的电子转移 .La系金属富勒烯中 ,金属原子转移 2或 3个电子给碳笼形成 + 2或 + 3价的金属离子和带有大量负电荷的碳笼 .尽管如此 ,金属富勒烯仍具有良好的接受电子的能力 [2 ,3] .大多数的 La系金属富勒烯 ( Y,La,Ce,Pr,Nd,Gd,Tb,Dy,Ho,Er,L u)的电化学方法研究表明 ,它们可以接受 5到 6个电子 ,但是 ,Sm的金属富勒烯的氧化还原性质尚未见报道 ,其主要原因是 Sm金属富勒烯的合成产率低 ,仅是 La金属富勒烯的 7% ,从而使得其分离非常困难 ,需要通过多步 HPLC循环才能得到 [4 ,5] ,高…     

Field—ion microscopy observation of single—walled carbon nanotubes

Field-ion microscopy(FIM),a tool for surface analysis with atomic resolution,has been employed to observe the end structure of single-walled carbon nanotubes(SWCNTs).FIM images revealed the existence of open SWCNT ends,Amorphous carbon atoms were also observed to occur around SWCNTs and traditional field evaporation failed to remove them.Heat treatment was found to be efficacious in altering the end structures of SWCNT bundles.Carbon and oxygen atoms released from heated tungsten filament are believed to be responsible for the decoration imposed on the SWCNT ends.     

Teleportation of a three—particle entangled W state

We have investigated the problem of teleporting a three-particle entangled W state and we propose a scheme based on entanglement spapping to complete the teleportation.We also put forward a scheme for the teleportation of a general W state by using nonmaximally entangled quantum channels.The probability of success of the latter scheme is obtained.     

一种聚苯胺膜微纳光纤氢离子浓度探针

提出了一种聚苯胺膜微纳光纤液体氢离子浓度探针,并研究了该光纤探针的氢离子浓度传感特性.传感部分由单模光纤-小芯径光纤-单模光纤对芯熔接而成,聚苯胺材料作为敏感膜涂覆于小芯径光纤.首先,对光纤探针传感原理和聚苯胺主链结构变化机理进行理论分析;然后,通过氢离子浓度传感实验进行验证并分析不同膜厚对光纤探针传感特性的影响;最后...     

Formation of domain reversal by direct irradiation with femtosecond laser in lithium niobate

We propose that domain inversion can be directly induced by femtosecond laser both theoretically and experimentally, which opens a path to achieve three-dimensional （3D） nonlinear crystal with a period in sub-micron-scale. A simulation of domain inversion is modeled by considering the temporal distribution of femtosecond pulses. The calculation results clarify that the domain inversions can happen within or after the interaction with the laser pulse, and the response time of domain inversion is in the picosecond level depending on the intensity and the materials. The domain reversal windows of lithium niobate by femtosecond laser are observed which agrees with theoretical predictions qualitatively.