杯[8]芳烃键合硅胶固定相的制备、表征及色谱性能

杯芳烃通过疏水Π-Π、氢键和静电等作用能与中性分子及离子形成包合物,在离子选择性电极、催化、分离和酶模拟等领域受到关注.已报道的杯芳烃键合固定相的制备方法^[1～3]都是先合成含杯芳烃硅烷化试剂,然后通过硅胶硅烷化反应制备键合固定相.其制备路线反应过程长,各种有机中间体纯化操作复杂.前文[4]曾以氯丙基键合硅胶为中间体,通过固相连续反应制备了氮杂冠醚键合硅胶固定相.本文采用固相连续反应制备了一种新型的对-叔丁基杯^[8]芳烃键合固定相,通过元素分析、红外光谱等手段获得键合相分子结构信息,以多环芳烃和二取代苯位置异构体为溶质,对固定相的色谱性能及保留机理进行了研究.     

含氮六元芳杂环的氨基化反应——Chichibabin反应

本文对含氮六元芳杂环的氨基化反应即Chichibabin反应进行了较为详细的讨论,并根据各种实验事实提出了Chichibabin反应可能存在的两种不同的机理.在非均相体系中进行的Chichibabin反应可能是通过吸附和单电子转移的机理进行的;而在均相体系中则可能是通过亲核的加成消除机理进行的.     

2,4,6-三硝基苯酚衍生化β-环糊精键合硅胶液相色谱固定相的合成与评价

β_环糊精键合硅胶经对甲苯磺酰化后 ,与2 ,4 ,6_三硝基苯酚(PA)反应得到2,4,6_三硝基苯酚衍生化 β_环糊精键合硅胶固定相 (PCDS) ;采用元素分析、漫反射傅里叶变换红外光谱等方法对其进行了表征 ;考察了PCDS对稠环芳烃、位置异构体、丹磺酰化氨基酸等物质的分离性能 ,并对其分离机理进行了初步探讨。     

LS-971脱氧保护型硫磺回收催化剂的制备及表征

介绍了LS-971脱氧保护型硫磺回收催化剂的制备及表征研究,主要对催化剂的载体、活性组分及助催化剂进行了筛选及分析表征,并与进口催化剂进行了对比.结果表明LS-971脱氧保护型硫磺回收催化剂的性能达到了国外同类催化剂水平.     

色谱法分离纯化富勒烯的研究进展

富勒烯是近年来研究较多的碳笼结构高分子化合物,基分离、纯化是影响该研究领域进展的关键因素。色谱法是目前分离富勒烯的重要手段,本文概述了该法在富勒烯分离、纯化中的应用,着重讨论了高效液相色谱固定相的发展。     

基于Lucas-Kanade算法的最大Gabor相似度大姿态人脸识别

在人脸识别科学研究和实际应用领域中,大角度姿态是影响人脸识别结果的主要因素之一,成为限制人脸识别技术进步的难点,而姿态的校正归一化是解决该问题的常用手段。首先通过加权的LK(Lucas-Kanade)算法得到侧脸块和对应正脸块的仿射变换参数,基于最大Gabor相似度寻找校正人脸姿态的最优参数。然后,以每一人脸块最优参数得到的平均Gabor相似度作为这一块人脸的识别权重,可以增加大姿态人脸识别的精度和稳健性。在FERET人脸数据库中进行了实验,当水平偏转角度为45°时,准确率达到97.3%,证明本文提出的以最大Gabor相似度作为加权LK算法参数提取的依据是有效的,得到的最优参数具有较好的光照无关性,而将平均Gabor相似度作为识别权重,有助于使算法的应用更加稳健和有效。     

羧基化氧化石墨烯的可控合成及血液相容性

采用自由基引发剂偶氮二异丁腈(AIBN)作为功能改性剂, 通过AIBN分解产生的异丁腈自由基进攻氧化石墨烯上五元环与七元环的缺陷点, 形成氰基改性氧化石墨烯中间体, 再通过水解反应制得羧基化氧化石墨烯[GeneO-C(CH₃)₂-COOH]纳米材料. 采用傅里叶变换红外光谱(FTIR), X射线衍射(XRD), 热重分析(TGA)和原子力显微镜(AFM)等方法对合成的材料进行了表征, 并采用复钙时间测试考察了材料的血液相容性. 研究结果表明, 氧化石墨烯中羧基的含量可以通过调整AIBN和GeneO的投料比来控制. 本方法不但可提高氧化石墨烯的羧基含量, 而且可使其具有良好的血液相容性.     

高比表面纳米二氧化钛胶体、多孔电极及DSC电池的制备

以钛酸四丁酯为前驱物,冰醋酸为水解抑制剂,浓硝酸为胶溶剂,结合溶胶-凝胶与水热处理法成功制备了具有高比表面积的纳米二氧化钛胶体.除水、酸后,浓缩并添加有机粘结剂制成了纳米TiO2浆料.刷制多孔电极并组成电池后测试了其光电特性.调整胶溶剂-浓硝酸的添加量,制备了具有不同颗粒大小、晶型、比表面积的TiO2纳米颗粒.为了提高多孔薄膜的光散射效应,在浆料中添加了400 nm TiO2粉体,研究了其掺入量对电池特性的影响.结果表明,当硝酸加入量为 1 mL、掺入20;大颗粒TiO2时,制备的电池效率达到4.19;(Jsc=8.32 mA/cm2, Voc=0.76 V, FF=66.31;).     

Determination of the relative permittivity of the AlGaN barrier layer in strained AlGaN/GaN heterostructures

Using the measured capacitance--voltage curves and the photocurrent spectrum obtained from the Ni Schottky contact on a strained Al_0.3Ga_0.7N/GaN heterostructure, the value of the relative permittivity of the AlGaN barrier layer was analysed and calculated by self-consistently solving Schr?dinger's and Poisson's equations. It is shown that the calculated values of the relative permittivity are different from those formerly reported, and reverse biasing the Ni Schottky contact has an influence on the value of the relative permittivity. As the reverse bias increases from 0 V to --3~V, the value of the relative permittivity decreases from 7.184 to 7.093.     

High power and high reliability GaN/InGaN flip-chip light-emitting diodes

High-power and high-reliability GaN/InGaN flip-chip light-emitting diodes (FCLEDs) have been demonstrated by employing a flip-chip design, and its fabrication process is developed. FCLED is composed of a LED die and a submount which is integrated with circuits to protect the LED from electrostatic discharge (ESD) damage. The LED die is flip-chip soldered to the submount, and light is extracted through the transparent sapphire substrate instead of an absorbing Ni/Au contact layer as in conventional GaN/InGaN LED epitaxial designs. The optical and electrical characteristics of the FCLED are presented. According to ESD IEC61000-4-2 standard (human body model), the FCLEDs tolerated at least 10\,kV ESD shock have ten times more capacity than conventional GaN/InGaN LEDs. It is shown that the light output from the FCLEDs at forward current 350mA with a forward voltage of 3.3\,V is 144.68\,mW, and 236.59\,mW at 1.0\,A of forward current. With employing an optimized contact scheme the FCLEDs can easily operate up to 1.0\,A without significant power degradation or failure. The life test of FCLEDs is performed at forward current of 200\,mA at room temperature. The degradation of the light output power is no more than 9\% after 1010.75\,h of life test, indicating the excellent reliability. FCLEDs can be used in practice where high power and high reliability are necessary, and allow designs with a reduced number of LEDs.