基于排队论的舰空导弹武器系统射击效能研究

阐述了舰空导弹的服务能力是其作战效能的重要因素之一.基于排队论,构建了舰空导弹服务概率模型,并给出了建立模型的步骤.通过想定的算例,运用此模型进行了舰空导弹武器系统的效能估算,校验了模型的合理性,解决了舰空导弹武器系统射击效能评估的问题.这种方法对舰空导弹武器系统的作战使用有一定的参考价值.     

Electrically and thermally conductive elastomer/graphene nanocomposites by solution mixing

The greatest challenge in developing polymer/graphene nanocomposites is to prevent graphene layers stacking; in this respect, we found effective solution-mixing polymers with cost-effective graphene of hydrophobic surface. Since graphene oxide is hydrophilic and in need of reduction, highly conducing graphene platelets (GnPs) of ∼3 nm in thickness were selected to solution-mix with a commonly used elastomer – styrene–butadiene rubber (SBR). A percolation threshold of electrical conductivity was observed at 5.3 vol% of GnPs, and the SBR thermal conductivity enhanced three times at 24 vol%. Tensile strength, Young's modulus and tear strength were improved by 413%, 782% and 709%, respectively, at 16.7 vol%. Payne effect, an important design criteria for elastomers used in dynamic loading environment, was also investigated. The comparison of solution mixing with melt compounding, where the same starting materials were used, demonstrated that solution mixing is more effective in promoting the reinforcing effect of GnPs, since it provides more interlayer spacing for elastomer molecules intercalating and retains the high aspect ratio of GnPs leading to filler–filler network at a low volume fraction. We also compared the reinforcing effect of GnPs with those of carbon black and carbon nanotubes.     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

基于GC-MS指纹图谱和化学计量学方法鉴别陈皮

制备了陈皮挥发油提取物并建立其气相色谱-质谱（GC-MS）指纹图谱,对不同批次的陈皮指纹图谱进行相似度评价;对其共有成分峰面积数据进行主成分分析（PCA）和层次聚类分析（HCA）。建立了具有16个共有峰的新会陈皮挥发油指纹图谱,通过化学计量学分析方法能将新会陈皮和其他陈皮样品准确区分开来;不同采摘期及贮存时间陈皮的成分呈现规律性特征。方法可用于不同产地、采摘期及贮存时间陈皮的鉴别,并为陈皮的质量控制提供依据。     

基于Windows7平台的高校计算机机房改造与实施

以郧阳师范高等专科学校计算机中心机房为例,介绍了基于Windows 7平台下机房建设改造过程中的硬件、软件及网络设备的方案选用,及工程实施过程中需要注意的问题和实践经验。     

Solidification of the Cu-35wt pct Fe Alloys with Liquid Separation

The microstructures of the Cu-35wt pct Fe alloys were investigated by melt-fluxing in combination with cyclic superheating and melt-spinning technique, respectively. Using the melt-fluxing with cyclic superheating technique, it was found that a complicated sub-microstructure formed in the separated minor phase, when the undercooling was 120 K (120 °C). The processes of the phase transformation from a liquid state to room temperature for undercooled Cu-35wt pct Fe alloys were discussed, in order to understand the solidification with metastable liquid separation. By means of melt-spinning technique, it was indicated that the microstructure of solidification for Cu-35wt pct Fe alloys could be refined due to the high cooling rate.     

Preparation of Silver Nanowires via a Rapid,Scalable and Green Pathway

Rapid synthesis of silver nanowires(Ag NWs) with high quality and a broad processing window is challenging because of the low selectivity of the formation of multiply twinned particles at the nucleation stage for subsequent Ag NWs growth.Herein we report a systematic study of the water-involved heterogeneous nucleation of Ag NWs with high rate(less than 20 min) in a simple and scalable preparation method.Using glycerol as a reducing agent and a solvent with a high boiling point,the reaction is rapidly heated to 210 ℃ in air to synthesize Ag NWs with a very high yield in gram level.It is noted that the addition of a small dose of water plays a key role for obtaining highly pure Ag NWs in high yield,and the optimal water/glycerol ratio is0.25%.After investigating a series of forming factors including reaction temperature and dose of catalysts,the formation kinetics and mechanism of the Ag NWs are proposed.Compared to other preparation methods,our strategy is simple and reproducible.These Ag NWs show a strong Raman enhancement effect for organic molecules on their surface.     

新型葡萄糖衍生物的合成及其对Al~(3+)的识别研究

以2-羟基-1-萘甲醛和D-氨基葡萄糖盐酸盐为原料,设计合成了一种新型的葡萄糖衍生物,其结构得到了1H NMR,ESI-MS和元素分析的确认。实验结果表明,该化合物在水溶液中对Al3+表现出高选择性和高灵敏度的荧光特性。