Lipophilicity measurement of drugs by reversed phase HPLC over Wide pH range using an alkaline-resistant silica-based stationary phase, XBridge Shield RP(18)

We propose a reversed phase HPLC (RP-HPLC) with an alkaline-resistant silica-based stationary phase, XBridge Shield RP(18), for the determination of the lipophilicity of drugs with diverse chemical nature ranging from acidic to basic. A set of 40 model compounds with well-defined solvatochromic parameters was selected to allow a broad distribution of structural properties. The chromatographic results showed that the lipophilicity index log k(w) obtained with XBridge Shield RP(18) was well correlated with experimental log P(oct) values (r(2)=0.96). Linear solvation free-energy relationship (LSER) analyses revealed that the retention mechanism of the stationary phase and 1-octanol/water partitioning were controlled by almost the same balance of intermolecular forces (hydrophobicity as expressed by the van der Waals volume V(w), H-bond acceptor basicity beta, and dipolarity/polarizability pi*). The results showed that XBridge Shield RP(18) phase overcomes the shortcomings of the silica-based stationary phases, the application of which to lipophilicity measurements had been limited to neutral and acidic compounds.     

连续函数的概念和性质剖析及其拓展教学研究

比较深入的剖析了连续函数的概念,对连续函数的三种常见定义方式进行了分析,以连续性的判断为例,分析了数学思维的特点,介绍了一个一般文献中不常见的重要结论,讨论了连续函数概念在理论、应用和数学概念进一步发展的拓展.     

In-column “click” preparation of hydrophobic organic monolithic stationary phases for protein separation

Two types of macroporous organic polymer monoliths based on glycidyl methacrylate (GMA), 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) were prepared inside stainless-steel tubes. Azide functionalities were firstly introduced on the surfaces of poly(GMA-co-DVB) and poly(VBC-co-DVB) monoliths to provide reactive sites for click chemistry. With the application of copper(I)-catalyzed (3 + 2) azide-alkyne cycloaddition, an in-column click-modification approach for covalent attachment of long alkyl chains onto polymer monoliths was developed. The column morphology and surface chemistry of the fabricated monolithic columns were characterized by the scanning electron microscopy, mercury intrusion porosimeter, Fourier transform infrared spectroscopy, and elemental analyses, respectively. The chromatographic performances of the “clicked” stationary phases were demonstrated with the high separation efficiency for a variety of proteins within 4 min.     

干涉光谱数据处理技术研究进展

干涉光谱成像技术是一类同时具有成像、光谱测量功能的新型信息获取技术,由于干涉光谱成像仪获取的数据是目标的干涉数据,是一种中间数据,不能为用户直接所用,必须通过数据处理技术进行处理才能得到高质量的光谱数据,最终为用户所用.文章将干涉光谱数据处理技术分为通用型和专用型两大类,首先介绍了通用型干涉光谱数据处理技术的发展历程,然后针对干涉光谱成像技术的分类,介绍了不同类型干涉光谱数据的提取方式,对近些年来国内外专用型干涉光谱数据处理技术的发展进行了分析介绍.最后,对干涉光谱数据处理技术的发展趋势进行了展望.     

基于光谱分类的端元提取算法研究

目前成熟的端元提取算法是基于单形体几何学的像元纯度指数(PPO)算法,N-FINDR,VCA等算法.这些算法从图像所有像元中提取纯光谱,具有提取速度慢、精度不高的缺点;部分算法需要进行光谱降维,不利于小目标信息的提取.该文提出先利用基于空间特征的光谱分类算法进行分类,将格个图像划分成空间相邻、光谱相似的若干类,每一类的...     

基于马赫-曾德干涉仪的色散转折效应及其传感性能模拟研究

设计了工作在近红外波段的硅基马赫-曾德尔干涉仪(MZI)折射率传感器。理论和仿真模拟分析表明,通过改变MZI的结构参数可以对输出干涉谱的色散转折特性进行调控,经过优化后色散转折点(DTP)所对应的波长可以调至近红外波段(1550 nm),通过改变MZI周围的环境折射率(SRI)可以使折射率灵敏度达到37500 nm/RIU。由于DTP两侧的干涉条纹对外界折射率响应有相反的特性,将干涉波谷的相对漂移量作为检测对象,能够将灵敏度提高2倍,即75000 nm/RIU。不同于常规基于光栅和波导耦合构架的DTP传感器,所设计的DTP结构中两个干涉模式互不相关且均可独立调控,并可根据需要灵活调控色散转折波长。     

Gradient based iterative parameter identification for Wiener nonlinear systems

This paper focuses on the identification problem of Wiener nonlinear output error systems. The application of the key-term decomposition technique provides a special form of the Wiener model with polynomials, where all the model parameters to be estimated are separated. To solve the identification problem of Wiener nonlinear output error systems with the unmeasurable variables in the information vector, an auxiliary model-based gradient iterative algorithm is presented by replacing the unmeasurable variables with their corresponding iterative estimates. The performances of the proposed algorithm are analyzed and compared by using numerical examples.     

Nitrogen fixed into HNO3 by pulsed high voltage discharge

By applying pulsed high voltage discharge to a needle-mesh reactor that using seven acupuncture needles as discharge electrode and stainless steel wire mesh as ground electrode, nitrogen from bubbling gas could be fixed into NO₂^? and NO₃^? with equivalent mol H⁺ produced in the liquid phase and a small amount of NO and NO₂ yielded in the gas phase. The HNO₂ was originally formed and then converted into HNO₃. The ·OH and H₂O₂ stimulated the conversion reaction from HNO₂ to HNO₃, which caused HNO₂ concentration increased in the first 12 min and then decreased until lower than its detection limit. The concentration of HNO₃ still increased with discharge time. After 36 min, HNO₃ was the only and ultimate product in the liquid. The total yield of HNO₂ and HNO₃ could be affected by processing parameters such as electric factors of peak voltage and frequency, mesh size of ground electrode and content of nitrogen in N₂/O₂ bubbling. Increasing peak voltage or frequency, the total yield of HNO₂ and HNO₃ increased. Gas composition had a heavy impact on the fixation efficiency that obtained its maximum value at an oxygen content of 66.7% with bubbling O₂/N₂ gas. At the end of the 36 min discharge, the HNO₃ concentration with bubbling air was 2.215 mmol L^?1 at an applied voltage of 25 kV, pulse repetition frequency of 140 Hz and ground electrode mesh of 20 × 20. The energy yield was about 1.22 g (HNO₃)/kWh.     

基于曲面棱镜的宽视场推帚式高光谱成像仪设计

设计了一种覆盖短波红外谱段的宽视场推帚式高光谱成像系统,可用于空间遥感平台搭载获取高光谱数据立方体,分析地表物质组成及其理化特性。采用曲面棱镜作为色散元件,它集色散和成像功能于一体,通过与Offner中继结构相结合,大大简化了光谱仪光学系统的设计。相比传统色散型光谱成像仪,其结构紧凑、体积小、重量轻,而且能够有效校正棱镜色散带来的谱线弯曲和色畸变的问题。相比同类型的基于Offner中继结构的光栅光谱成像仪,其能量利用率高。分析了曲面棱镜的近轴光学理论和Offner中继结构的成像特点,给出了光谱仪的设计指标和结果,并对其光谱成像质量进行了评价。     

一类Green函数变号的二阶两点边值问题正解的存在性

讨论了Green函数变号的二阶两点边值问题：其中f：[0,1]×[0,＋∞）→[0,＋∞）连续.利用Guo-Krasnosel＇skii不动点定理得到了正解的存在性.