A Monte Carlo study of spherical electrical double layer of macroions-polyelectrolytes systems in salt free solutions

A canonical Monte Carlo simulation is performed to investigate the microstructure and the electrical double layer (EDL) of polyelectrolytes around macroions in the bulk systems based on the primitive model. We explore the influences of particles size, chain length, and charge density of polyelectrolytes on the microscopic behavior of the macroions-polyelectrolytes systems. The simulation results show that the surface charge density and the chain length of the polyelectrolytes are two key factors that affect the microstructure of polyelectrolytes around the macroions and potential of mean force between the macroions as well as the zeta potential of the spherical EDL constructed by polyelectrolytes. The high surface charge density of a polyelectrolyte leads to the polyelectrolyte acting as a bridge for the aggregation of macroions, causing the presence of the attraction between macroions. The polyelectrolytes with a long chain length present a cooperativity effect for the adsorption of the polyelectrolytes on the surface of the macroions. Furthermore, the two key factors both induce the overcharge of the macroions. The longer the chain length and the higher surface charge density of the polyelectrolytes, the stronger is the overcharge.     

随机需求下物流服务供应链订购策略研究

针对由单个物流服务提供商和集成商组成的物流服务供应链,基于集中化模式、纳什博弈模式和Stackelberg博弈模式三种典型模式,考虑市场需求随机且受服务质量缺陷承诺水平的影响,探讨物流服务供应链的订购与质量缺陷承诺策略问题。通过分析发现:物流服务质量缺陷承诺水平随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致;集中化模式下的物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增大而递减,但在其他两种合作模式下物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增加而增加;在三种模式下,物流服务供应链的整体利润随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致。     

镜面物体往复通过弱湍流大气系统的成像

分别利用部分相干理论、以广义随球波函数为基础的Ｋａｒｈｕｎｅｎ－Ｌｏｅ′ｖｅ展开和相干成像理论研究了弱湍流像差大气照明系统互强度函数传输特征和位地湍流介质中镜面物体成像规律。结果表明：仅当反射光束相干尺度（成像光束等效直径）小于成像孔径的尺度时才能改善湍流大气中两次成像的质量。     

Epitaxial growth of metals with high Ehrlich–Schwoebel barriers and the effect of surfactants

Interlayer diffusion in epitaxial systems with a high energy barrier at the atomic steps – the so-called Ehrlich–Schwoebel (ES) barrier – is strongly reduced. As a consequence of this, a continuous accumulation of roughness takes place during growth. This undesirable effect can be corrected by using surfactant agents. We have studied the influence of the ES barrier on the preparation of epitaxial films on Cu(111), and the surfactant effect of a monolayer of Pb. Received: 21 April 1999 / Accepted: 17 August 1999 / Published online: 6 October 1999     

煤的工业分析至元素分析的BP神经网络预测模型

以大量煤质分析数据为基础，建立了利用煤工业分析数据（ 包括水份、灰份、挥发份及热值） 计算元素分析数据的ＢＰ神经网络预测模型，并将该模型与现有经验公式进行了比较，结果表明神经网络模型有很好的推广能力。可以满足工业应用的要求     

Program schedule: Symposium on statistical approaches to macromolecular systems in honor of Robert Simha

Abstract

Atomic force microscopy (AFM) has been applied to observe single-chain polymethylmethacrylate (PMMA) particles that were stored for six months at room temperature after being sprayed from very dilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Nearly monodisperse PMMA standards of molecular weights ranging from 7.90 × 10⁴ to 1.3 × 10⁶ were used to investigate the effect of molecular weight (MW) on the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight has found to be identical in spite of different solvents used for solution spraying. Molecular weight dependence of the particle dimension was also found. The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared with the values estimated from molecular weight and density.