MCM-41-supported bidentate phosphine palladium(0) complex: a highly active and recyclable catalyst for the Sonogashira reaction of aryl iodides

The first MCM-41-supported bidentate phosphine palladium(0) complex has been prepared. This complex is a highly efficient catalyst for Sonogashira reaction and can be reused at least 10 times without any decrease in activity.     

FREE STANDING FILM OF POLYANILINE

A free standing film of polyaniline as large as 18 cm×18cm×0.002 cm can be obtained by evaporation of a solution of the chemically synthesized base in NMP. Its structure was examined by the elemental analysis, IR, U.V.-visible spectra, XPS, DSC, SEM and X-ray scattering and its conducting behavior as well as electrochemical properties were studied. Results show that the composition, structure of main chain, physical properties of the free standing film of polyanilme is similar to that of the powder. However, some differences in its electronic structure, conductivity at room temperature and potential of redox couple between the flee standing film and powder are observed, which may be due to cross-linking of the film of polyaniline.     

细胞松弛素B阻断微核法鉴定男性个体辐射敏感性的方法初探

初步研究了男性个体辐射敏感性的鉴定方法及标准。采集50名男性志愿者的外周血，分别给予不同剂量X射线照射，采用细胞松弛素B阻断双核法测定微核率(MNF)，通过二阶多项拟合法，绘制微核剂量效应选项中心标准曲线，将个人微核剂量效应曲线与标准曲线比对后判断个体辐射敏感性。 $0.0\sim2.5 $ Gy剂量范围内，剂量效应二阶多项拟合的中心方程为(MNF=0.014 7+0.036 2D+0.023 1D 2， r=0.726)。50名志愿者中，辐射敏感的有13人，辐射抗性的有14人，基本符合正态分布。Spearman秩和相关分析结果显示，MNF在各个辐射剂量点与辐射敏感性均存在正相关,与辐射抗性呈负相关,MNF随剂量增加而增加。本研究初步建立了“以线代点”男性个体辐射敏感性鉴定方法,并发现男性外周血淋巴细胞的本底微核率与个体辐射敏感性呈正相关。     

固相烧结法制备锂离子电池正极材料Li2FeP2O7及其电化学性能研究

介绍了一种先冷冻干燥后固相烧结制备正极材料Li₂FeP₂O₇的方法. 利用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)对材料的组成和形态进行表征, 并通过循环伏安曲线(CV)和电化学阻抗谱(EIS)研究了Li₂FeP₂O₇材料的电化学性能. 研究发现, 合成Li₂FeP₂O₇的最佳温度为590 ℃, 此温度下反应较完全且产物杂质较少, 1.6C倍率下的放电比容量达到55 mA·h·g^?1, 明显高于其它温度下合成样品的放电比容量. 该温度下合成的Li₂FeP₂O₇还具有低阻抗和较大的交换电流密度, 说明这种合成方式有利于提高锂离子在Li₂FeP₂O₇中的扩散.     

Graded Antisimple Radicals

We introduce the graded version of the antisimple radical S, the graded antisimple radical SG. When |G| < , we show that SG = Sref = SG, where Sref denotes the reflected antisimple radical and SG denotes the restricted antisimple radical.     

压力对聚苯胺导电性的影响

 导电高聚物聚苯胺薄膜经过定向拉伸后，其有序度、电导及跃迁势垒都发生了很大变化。本文研究了准静水压力对定向拉伸前后，聚苯胺薄膜电学性质的影响。发现未定向拉伸的聚苯胺薄膜的电导随压力单调增加，跃迁势垒T₀随压力单调减少，而定向拉伸后的聚苯胺薄膜则在0.47 GPa出现电导的极大值，在0.35~0.71 GPa之间出现T₀的极小值，这个异常行为与聚乙炔、聚噻吩等导电高聚物均不相同。     

Simulation of the Burridge-Knopoff model of earthquakes with variable range stress transfer

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior, such as Gutenberg-Richter scaling and the relation between large and small events, which is the basis for various forecasting methods. Although cellular automaton models have been studied extensively in the long-range stress transfer limit, this limit has not been studied for the Burridge-Knopoff model, which includes more realistic friction forces and inertia. We find that the latter model with long-range stress transfer exhibits qualitatively different behavior than both the long-range cellular automaton models and the usual Burridge-Knopoff model with nearest-neighbor springs, depending on the nature of the velocity-weakening friction force. These results have important implications for our understanding of earthquakes and other driven dissipative systems.     

Robust adaptive synchronization of uncertain complex networks with multiple time‐varying coupled delays

In this article, the synchronization problem of uncertain complex networks with multiple coupled time‐varying delays is studied. The synchronization criterion is deduced for complex dynamical networks with multiple different time‐varying coupling delays and uncertainties, based on Lyapunov stability theory and robust adaptive principle. By designing suitable robust adaptive synchronization controllers that have strong robustness against the uncertainties in coupling matrices, the all nodes states of complex networks globally asymptotically synchronize to a desired synchronization state. The numerical simulations are given to show the feasibility and effectiveness of theoretical results. © 2014 Wiley Periodicals, Inc. Complexity 20: 62–73, 2015     

Optical properties of two-dimensional perovskites

The optical properties of two-dimensional (2D) perovskites recently receive numerous research focus thanks to the strong quantum and dielectric confinement effects. In addition to the strong excitonic effect at room temperature, 2D perovskites also have appealing features that their optical properties can be flexibly tuned by alternating organic or inorganic layers. Particularly, 2D chiral perovskites and 2D perovskites based heterostructures are emerging as new platforms to extend their functionalities. To optimize performance of 2D perovskites-based optoelectronic devices, it is critical to understand the fundamentals and explore the strategies to engineer their optical properties. This review begins with an introduction to the excitons and self-trapped excitons of 2D perovskites. Subsequently, inorganic/organic layer effects on optical properties and 2D perovskites based heterostructures are discussed. We also discussed the nonlinear optical properties of 2D perovskite. We are looking forward to that this review can stimulate more efforts to understand and optimize the optical properties of 2D perovskites.     

A combined treatment of hydration and dynamical effects for the modeling of host–guest binding thermodynamics: the SAMPL5 blinded challenge

As part of the SAMPL5 blinded experiment, we computed the absolute binding free energies of 22 host–guest complexes employing a novel approach based on the BEDAM single-decoupling alchemical free energy protocol with parallel replica exchange conformational sampling and the AGBNP2 implicit solvation model specifically customized to treat the effect of water displacement as modeled by the Hydration Site Analysis method with explicit solvation. Initial predictions were affected by the lack of treatment of ionic charge screening, which is very significant for these highly charged hosts, and resulted in poor relative ranking of negatively versus positively charged guests. Binding free energies obtained with Debye–Hückel treatment of salt effects were in good agreement with experimental measurements. Water displacement effects contributed favorably and very significantly to the observed binding affinities; without it, the modeling predictions would have grossly underestimated binding. The work validates the implicit/explicit solvation approach employed here and it shows that comprehensive physical models can be effective at predicting binding affinities of molecular complexes requiring accurate treatment of conformational dynamics and hydration.