Crystallographic report: Bis(tripyridyldiamine)zinc(II) tetrabromozincate(II) hydrate

The zinc(II) atom in the complex cation of [Zn(tpda)₂][ZnBr₄]·H₂O is octahedrally coordinated, whereas the zinc(II) atom in the anion is tetrahedrally coordinated. The cations and the anions are connected by hydrogen bonds, affording a two‐dimensional network. Copyright © 2005 John Wiley & Sons, Ltd.     

一种改进的Snake算法

针对动态轮廓模型特性，本提出了一种能量函数的选取和收敛算法改进的新方法，结果表明，该方法在实际应用中效果理想。     

Crystallographic report: Bis[tris(2‐pyridyl)amine]cadmium(II)‐di‐µ‐chloro‐dichloro‐cadmium(II), [(C5H4N)3N]2CdCl2CdCl2

In the dinuclear molecule of [(C₅H₄N)₃N]₂CdCl₂CdCl₂, one cadmium is octahedrally coordinated by a Cl₂N₄ donor set and the other cadmium is tetrahedrally coordinated by four chlorine atoms. The dinuclear units are connected by π–π interactions to give a two‐dimensional network. Copyright © 2003 John Wiley & Sons, Ltd.     

Binary classification of aqueous solubility using support vector machines with reduction and recombination feature selection

Aqueous solubility is recognized as a critical parameter in both the early- and late-stage drug discovery. Therefore, in silico modeling of solubility has attracted extensive interests in recent years. Most previous studies have been limited in using relatively small data sets with limited diversity, which in turn limits the predictability of derived models. In this work, we present a support vector machines model for the binary classification of solubility by taking advantage of the largest known public data set that contains over 46?000 compounds with experimental solubility. Our model was optimized in combination with a reduction and recombination feature selection strategy. The best model demonstrated robust performance in both cross-validation and prediction of two independent test sets, indicating it could be a practical tool to select soluble compounds for screening, purchasing, and synthesizing. Moreover, our work may be used for comparative evaluation of solubility classification studies ascribe to the use of completely public resources.     

Applications of micro-scale combustion calorimetry to the studies of cotton and nylon fabrics treated with organophosphorus flame retardants

Effective testing methods are critical for developing new flame retardant textiles by the industry. However, the current testing methods all have limitations. In this research, we applied micro-scale combustion calorimetry (MCC) for evaluating the flammability of the cotton woven fabric treated with a traditional reactive organophosphorus flame retardant in combination with a synergistic nitrogen-containing additive and the nylon-6,6 woven fabric treated with a hydroxyl-functional organophosphorus oligomer and crosslinkers. We found that MCC is capable of differentiating small differences among the treated fabric samples with similar flammability. MCC is able to make quantitative measurement of the peak heat release rate, the most important parameter related to fire hazard of materials, of textile whereas such analysis is more difficult using cone calorimetry due to textile fabrics’ low thickness. By using the thermal combustion parameters measured by MCC, we were able to calculate the limiting oxygen index (LOI) of various treated cotton fabric samples with near-perfect agreement between the experimentally measured and the predicted LOI values of treated cotton fabrics. We also compared the capability of MCC and differential scanning calorimetry for analyzing flame retardant cotton textiles.     

In vivo comparison of the optical clearing efficacy of optical clearing agents in human skin by quantifying permeability using optical coherence tomography

The objective of this work is to quantify and compare the optical clearing efficacy of glucose, propylene glycol, glycerol solutions through the human skin tissue in vivo by calculating permeability coefficient of three solutions. Currently, the permeability coefficient of agent in tissues was extracted from optical coherence tomography (OCT) amplitude data mainly through the OCT signal slope and the OCT amplitude methods. In this study, we report the OCT attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the permeability coefficient during the optical skin clearing procedure. The permeability coefficients for 40% propylene glycol, glucose and glycerol were (2.74 ± 0.05) × 10(-6) cm s(-1), (1.78 ± 0.04) × 10(-6) cm s(-1) and (1.67 ± 0.04) × 10(-6) cm s(-1), respectively. It could be clearly seen that the permeability coefficient of the 40% propylene glycol solution is higher than that of 40% glucose solution, and the permeability coefficient of the 40% glucose solution is higher than that of the 40% glycerol solution. These indicate 40% propylene glycol solution is more effective than others in the human skin in vivo. We then compare and prove consistency of optical clearing efficacy figured out by three different methods.     

碳纳米管阴极强流脉冲发射特性实验

 在2 MeV直线感应加速器注入器平台上研究了采用浸渍涂覆方法制备的大面积碳纳米管阴极发射体的强流发射特性。研究结果表明：在脉冲高压电场下,碳纳米管阴极具有强流电子束发射能力,发射电流密度较大;碳纳米管阴极发射电子过程为场致等离子体发射。实验过程中,阴极端取样电阻环收集到的最大发射电流达350 A,阳极端法拉第筒收集的发射电流为167 A,最大阴极发射电流密度为19.4 A/cm²。     

频率自动跟踪超声波电源设计

针对超声波电源工作时负载状态改变,换能系统产生谐振漂移的问题,提出了一种基于STM32的频率自动跟踪超声波电源的设计。电源逆变电路采用带辅助网络的全桥结构,阻抗匹配电路选择了一种改进型的T型匹配网络,应用PWM移相调功技术控制电源的输出功率,通过数字鉴相技术得到电压电流的相位差作为电路谐振状态的反馈信号,结合STM32主控制器进行PI控制,调节PWM波的输出频率使电路始终工作于谐振状态,实现了谐振频率的自动跟踪。最后基于该设计方案,实际制作了一款应用于超声波清洗仪的电源,并通过实验验证了该电源具有输出功率稳定,负载适应性强,输出频率自动跟踪等特点。     

纳米复合体系中环形高分子链的构型

采用分子动力学模拟方法对纳米复合体系中环形高分子链的构型及纳米粒子的集聚行为进行了研究.在不同纳米粒子/高分子链吸附能作用下,复合体系中纳米粒子表现出3种集聚行为：直接接触集聚、均匀分散以及高分子与纳米粒子间的桥接集聚.同时考虑了环形高分子链的刚性强度,得到了环形高分子链的3个构型：中间吸附、马鞍型吸附和轨道绕行型吸附.研究发现,增强环形高分子链的刚性将有助于促进纳米复合体系中纳米粒子间的分散.     

Bernstein-Sikkema算子逼近

研究Ｂｅｒｎｓｔｅｉｎ－Ｓｉｋｋｅｍａ算子的逼近问题,得到强型正定理和弱型逆定理,改进了文献［１］的结果