“锥形嵌套"结构CNx纳米管的生长机理及拉曼光谱研究

在氮气、氢气以及氯化铵热解产生的氨气环境下,以钴作为催化剂,在780℃—940℃温度范围内使二甲苯与二茂铁受热分解,合成了CNx纳米管.在高分辨率透射电子显微镜下观察,合成的纳米管呈现“锥形嵌套”的形貌特征.从不同结构的分子面形成能的角度探讨了CNx纳米管的催化生长机理.不同温度下所制备样品的拉曼光谱研究表明,ID/IG值可以反映氮的掺杂所带来的纳米管结晶有序程度的降低,并通过G带向高波数移动证实了氮的掺杂.     

一种基于新型查表方法的统一计算设备架构并行计算全息算法

为解决点源法计算全息速度较慢的问题,提出了一种新的查表算法,命名为三角函数查表法(T-LUT算法)。该算法是基于点源法基本的数学公式,通过一系列数学近似与恒等变换,生成了一种纯相位查找表,该查找表具有三维特性,并具有生成速度快、精度高、占用内存少等特点,克服了点源法重复计算相位的缺点。同时采用统一计算设备架构(CUDA)并行计算在图形处理器(GPU)上加以实现,并进行了三次并行优化。在算法的验证与对比实验中,采用单显卡(GPU显卡)实现T-LUT算法,在不牺牲全息图再现像质量的前提下,成功地将点源法计算全息的速度大幅度提升。实验发现在不同的物空间采样点数量的情况下,速度相对于点源法GPU运算提升30倍至近千倍不等。     

向列相液晶中空间光孤子的观测

分别以He-Ne激光器、半导体激光器和Ar⁺激光器作为光源照射液晶材料，在低光强入射的情况下均观察到了光束的自聚焦现象以及空间光孤子的形成，观察到了长度l>5mm的孤子波和多模空间光孤子，并对空间孤子的产生条件及特性进行了讨论. 关键词： 自聚焦 空间光孤子 向列相液晶     

HFSiS构型及其稳定性的理论研究

利用密度泛函理论对三线态HFSiS分子结构及其稳定性进行了详细的理论研究.在B3LYP/6-311G**水平上计算出了各驻点的优化构型、振动频率,并对各个振动模式加以归属,在同样的理论水平上进行了IRC计算;CCSD(T)结合6-311G**基组对于驻点进行单点能及相对能量的计算;根据振动模式分析来阐明三线态势能面上各驻点之间的变化,并与单线态势能面进行比较.计算结果表明,三线态HFSiS分子存在6种异构体,3HFSiS结构在动力学和热力学上都是最稳定的,实验上应该可以观测到;在两组键旋转异构体当中,结构-2具有一定的动力学稳定性,而结构-1动力学稳定性较差;3SiSHF在动力学上和热力学上都是最不稳定的结构.     

计入地面附加衰减的声屏障插入损失估算方法*

基于理论推导和计算,给出了公路声屏障声学设计中,在考虑地面附加衰减情况下计算插入损失的方法。该方法综合考虑了有限长线声源无限长声屏障绕射声衰减量、有限长线声源地面衰减量及遮蔽角对插入损失的影响。通过与《声屏障声学设计和测量规范》（HJ/T90-2004）的计算结果的对比,验证了本文所给方法的精确性及可行性,并对规范所给地面衰减修正量进行了商榷。最后,给出了当预测点位于有限长路段中央法线上时,通过计算线声源地面衰减量得到计算插入损失所需参数值,再计算插入损失的简便方法。本研究为存在地面附加衰减情况下有限长声屏障插入损失计算提供了一个新的参考方法。     

基于红外光谱研究沥青燃烧机理和有害气体成分分析

利用Rosemount气体分析仪和定碳炉搭建起固定床燃烧反应试验平台,通过红外光谱分析技术定量分析沥青及其胶浆在高升温速率条件下燃烧反应的有毒气态产物成分、及其释放规律。研究表明,在高升温速率、近等温条件下,沥青及胶浆的燃烧过程可近似分为活泼挥发组分析出燃烧、二次挥发析出结合残炭燃烧两个阶段,其主要气态产物为CO₂,CO,NO,NO₂及SO₂。沥青材料中活泼挥发组分含量是影响燃烧气态产物释放规律的关键因素之一,减少沥青材料中活泼挥发组分的含量可有效降低燃烧气态产物的生成、尤其是CO的产生。     

郡县制国家现代化：中央政府如何扩大公共事务治理职能

郡县制国家的传统职能是“管人”,但是在当代,为了适应现代世界,需要加强和完善“管事”的职能。然而,加强“管事”的职能遇到的一大障碍,是“管事”与“管人”通常难以分开,带来管事与管人的冲突。在全国性公共事务上,面对管事与管人的冲突,郡县制国家的一种改革方向,即建立中央统一管理与地方属地管理相结合的体制,既扩大中央政府的治理职能,同时又发挥纵向约束机制的作用,从而能改善全国性公共事务治理。此种中央统一管理与地方属地管理相结合的体制,通常不是中央政府事先设计出来的,而是在改革过程中,经由中央政府与地方政府的策略性互动过程,逐渐建立起来的。因此,郡县制国家蕴含着一种潜力,即在公共事务治理上,包括地方公共事务和全国性公共事务,可以引入和发挥“纵向约束机制”的作用,使得国家既保持“管人”的基本体制不变,又能提高治理能力。     

Flexible and stretchable electrodes for next generation polymer electronics: a review

Transparent conductive electrodes play a significant role in the fabrication and development of optoelectronic devices. As next generation optoelectronic devices tend towards mobile and wearable devices, the added attribute of flexibility or stretchability for these electrodes becomes increasingly important. However, mechanical requirements aside, transparent conductive electrodes must still retain high transparency and conductivity, with the metrics for these parameters being compared to the standard, indium tin oxide. In the search to replace indium tin oxide, two materials that have risen to the forefront are carbon nanotubes and silver nanowires due to their high transparency, conductivity, mechanical compliance, and ease of fabrication. This review highlights recent innovations made by our group in electrodes utilizing carbon nanotubes and silver nanowires, in addition to the use of these electrodes in discrete devices and integrated systems.     

Determination of pseudo‐ginsenoside GQ in human plasma by high performance liquid chromatography–tandem mass spectrometry

A specific, sensitive and rapid method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC‐MS/MS) was developed for the determination of pseudo‐ginsenoside GQ in human plasma. Liquid–liquid extraction was used to isolate the analyte from biological matrix followed by injection of the extracts onto a C₈ column with isocratic elution. Detection was carried out on a triple quadrupole tandem mass spectrometer (API‐4000 system) in multiple reaction monitoring mode using negative electrospray ionization. The mobile phase consisted of methanol–10 mm ammonium acetate (90:10, v/v) and the flow rate was 0.3 mL/min. The method was validated over the concentration range of 5.0–5000.0 ng/mL for plasma. Inter‐ and intra‐day precisions (relative standard deviation) were all within 15% and the accuracy (relative error) was ≤9.4%. The lower limit of quantitation was 5.0 ng/mL. The pseudo‐ginsenoside GQ was stable after 8 h at room temperature, 24 h at autosampler and three freeze–thaw cycles (from ?30 to 25 °C). The method was successfully applied to the pharmacokinetic study of pseudo‐ginsenoside GQ in healthy Chinese volunteers. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermal-oxidative degradation of high-amylose corn starch

Thermal oxidation degradation of high-amylose (80 %) cornstarch has been studied using thermogravimetry analyser coupled to Fourier transform infrared spectroscopy (TG-FTIR). The linear structure of amylose provides a modal material to understand how the starch microstructure affects on the decomposition mechanisms. Kinetics of the thermal oxidation has been studied using different methods. It is found that the thermal oxidation degradation is more complex than thermal degradation, thermal oxidation degradation kinetics of the starch can be interpreted in terms of multi-step degradation mechanism, the activation energies obtain from Flynn–Wall–Ozawa (F–W–O) method and modified Coats–Redfern method are in good agreement. TG-FTIR and FTIR results confirm that the thermal oxidation mechanism of starch is a process containing long chain scission and glowing combustion.