单链表在离子发动机光学系统粒子模拟中的应用

 目前离子发动机光学系统数值模拟大多采用PIC方法,由于该方法需要跟踪单个粒子的运动,因此需要存储每个粒子的位置信息与运动信息。传统的粒子模拟程序中,保存粒子信息大多采用数组的方式,但是采用这种方式存在弊端,例如对粒子总数变化的自适应不好。基于此开发了一种使用链式存储结构的粒子模拟程序,该程序使用带头节点的单向链表存储粒子信息。使用基于链式存储结构的PIC方法对离子发动机光学系统进行了粒子模拟,验证了链式粒子信息存储方法在粒子模拟中的可用性。模拟表明：（1）在粒子模拟中采用链式存储结构存储粒子信息,无需预先指定最大粒子总数,程序可自适应粒子总数的变化,因此无需进行试算,节省了计算时间;（2）在粒子模拟中采用链式存储结构,由于不存在内存资源的浪费,因而可显著提高程序的存储效率与计算效率。     

New fluorescent benzocrown ether derivatives of tetrathiafulvalene: facile synthesis and recognition properties

Two new fluorescent crown ether derivatives of tetrathiafulvalene (TTF) (2a and 2b) were synthesized and characterized; their electrochemical response to Na⁺ ions and fluorescence properties were investigated. The mechanism of the strong fluorescence has also been explored.     

Nonlinear-Ion-Acoustic-Wave Instability, Threshold, Half Width of Trapped Region and Transition Region

Nonlinear Landau damping of ion acoustic wave (IAW) is one of the most important phenomena in the ionosphere and in space and laboratory plasma as well. The instability growth rate of the IAW with electron drift, the amplitude threshold for exciting the nonlinear effects, the half widths of the trapped region with the trapped electrons are studied experimentally. Under the experimental conditions, it is shown that there is a frequency range of 140--160 kHz, within which the growth rate has the largest value of about 6×10⁴--1.5×10⁵ s^-1. We obtain the transitional region width caused by collisions theoretically and experimentally, for the first time to our knowledge. The experimental results are in good agreement with the theoretical prediction.     

α-Ni(OH)2的研究进展

摘要本文综述了α-Ni（OH）：在碱液中稳定存在的影响因素,对保持Ni（OH）2的alpha型结构所需条件及解决措施做了阐述;介绍了国内外α-Ni（OH）2电极的最新研究进展,着重叙述了Al^3＋、Mn^3＋和Zn^2＋替代Ni^2＋的α-Ni（OH）2的制备、稳定性和电化学性能以及尿素热分解制备的α-Ni（OH）2的特性;展望了纳米级α-Ni（oH）2的研究及应用前景。     

Nanofibril self-assembly of an arylene ethynylene macrocycle

Nanofibril structures have been fabricated from an arylene ethynylene macrocycle (AEM), which consists of a square frame corner-joined by four carbazole moieties. The fabrication was performed through a gelating process by cooling a warm, homogeneous solution in cyclohexane at high temperature (e.g., 100 degrees C) to room temperature. During the gelation, the molecules become organized, with optimal pi-pi stacking in cooperation with the side-chain association. The favorable pi-pi stacking facilitates the 1D growth of molecular assembly.     

Synergistic effects between a triazine-based charring agent and aluminum phosphinate on the intumescent flame retardance of thermoplastic polyether ester

The triazine-based charring agent (CFA) with perfect charring ability was synthesized and characterized. The synergistic effects between CFA and aluminum phosphinate (AlPi) on flame retardancy, thermal degradation, and flammability properties of thermoplastic polyester-ether elastomer (TPEE) were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test (CCT), thermogravimetric analysis (TGA), laser Raman spectroscopy (LSR) and scanning electron microscopy (SEM). The results from UL-94 test showed that, by compounding 14 wt% AlPi and 4 wt% CFA with TPEE, the LOI value reached 28.5% and the UL-94 rating reached V-0 (1.6 mm). TGA results indicated that there is good synergistic charring ability between CFA and AlPi, especially the increased residues at high temperature (T > 700 °C). The CCT test results showed that CFA could change the combustion behavior of TPEE and effectively accelerate the formation of expanded carbon layers. The residues after combustion were measured by LRS and SEM, demonstrating that CFA can promote the formation of dense and stable carbon layers during the combustion, which could inhibit the melt dropping and improve the fire retardancy of TPEE composites. Thus, CFA was a promising synergistic agent in halogen-free flame retardant TPEE.     

Interactions of polyelectrolyte brushes with oppositely charged surfactants

Using Brownian dynamics simulations, we study the effect of the charge ratio, the surfactant length, and the grafting density on the conformational behavior of the complex formed by the polyelectrolyte brush with oppositely charged surfactants. In our simulations, the polyelectrolyte chains and surfactants are represented by a coarse-grained bead-spring model, and the solvent is treated implicitly. It is found that varying the charge ratio induces different morphologies of surfactant aggregates adsorbed onto the brush. At high charge ratios, the density profiles of surfactant monomers indicate that surfactant aggregates exhibit a layer-by-layer arrangement. The surfactant length has a strong effect on the adsorption behavior of surfactants. The lengthening of surfactant leads to a collapsed brush configuration, but a reswelling of the brush with further increasing the surfactant length is observed. The collapse of the brush is attributed to the enhancement of surfactants binding to polyelectrolyte chains. The reswelling is due to an increase in the volume of adsorbed surfactant aggregates. At the largest grafting density investigated, enhanced excluded volume interactions limit the adsorption of surfactant within the polyelectrolyte brush. We also find that end monomers in polyelectrolyte chains exhibit a bimodal distribution in cases of large surfactant lengths and high charge ratios.     

Study on Biological Safety of Polyvinyl Alcohol/Collagen Hydrogel as a Tissue Substitute (II)

Physically crosslinked polyvinyl alcohol/collagen composite hydrogels were prepared by a cyclic freezing-drying technique. The biological properties of the hydrogels, including hemolysis, anaphylaxis, pyrogen and acute systemic toxicity tests and implantation in-vivo, were investigated. The hemolysis test suggested that the polyvinyl alcohol/collagen, with a hemolysis index of 1.19%, did not have an obvious hemolysis reaction. There was no toxicosis or death cases observed in the acute systemic toxicity test, and the hydrogel showed no anaphylaxis or pyrogen response. The composite hydrogel showed a good histological compatibility in the in-vivo study. The results indicated that the polyvinyl alcohol/collagen composite hydrogels have promising applications for pharmaceutical and biomedical fields.