幅相一致行波管非线性理论与计算机模拟

 采用谐波互作用的行波管二维大信号非线性理论，建立了高频电路结构和外部工作条件零散模型，对影响增益、相位频率特性的主要因素进行了理论分析和数值计算，开发了可动态实时显示行波管工作状态的可视化科学计算软件，并利用该软件全面地分析了某管型的幅相一致特性，为新近研制的幅相一致行波管提供了很有价值的计算结果。     

高分辨侧扫及合成孔径声纳图像与回波中类似水雷目标计算机检测与分类

计算机辅助目标识别与分类技术有可能可靠地在海底发现水雷及其它感兴趣的目标,高效省时,一致性强,不受操作员个体因素影响。自90年代以来,是多个研究部门的热点课题。近年来,合成孔径侧扫声纳技术日趋成熟,能提供更高分辨率的声图,更是促进了自动识别与分类的发展。 本文综合评述了高分辨侧扫及合成孔径声纳图像与回波中类似水雷目标- MLO (Mine Like Object)-计算机检测与分类-CAD/CAC（Computer Aided Detection/ Computer Aided Classification）-研究的发展,现状及趋向。     

高效液相色谱-串联质谱法对家兔血浆中奥司他韦浓度的测定

建立了家兔血浆中奥司他韦的高效液相色谱-串联质谱测定方法。以ZORBAX XDB-C18柱为色谱柱,乙腈-0.4%甲酸水溶液为流动相,梯度洗脱;流速300μL.min-1;柱温:20℃。质谱条件为气动辅助电喷雾离子源(ESI),检测方式为正离子多离子反应监测(MRM),以m/z313/166、313/208为定性离子对,m/z313/166为定量离子;生物样品采用固相萃取方法处理。奥司他韦的线性范围为0.05~500μg.L-1,定量下限达0.05μg.L-1,日内、日间相对标准偏差均小于6%,回收率为91%~93%,结果表明该法准确、灵敏、特异,适用于生物样品中奥司他韦的测定。该文还进一步探讨了奥司他韦主要质谱碎片的产生机理。     

Comparison between evaporative light scattering detection and charged aerosol detection for the analysis of saikosaponins

Saikosaponins are triterpene saponins derived from the roots of Bupleurum falcatum L. (Umbelliferae), which has been traditionally used to treat fever, inflammation, liver diseases, and nephritis. It is difficult to analyze saikosaponins using HPLC-UV due to the lack of chromophores. Therefore, evaporative light scattering detection (ELSD) is used as a valuable alternative to UV detection. More recently, a charged aerosol detection (CAD) method has been developed to improve the sensitivity and reproducibility of ELSD. In this study, we compared CAD and ELSD methods in the simultaneous analysis of 10 saikosaponins, including saikosaponins-A, -B₁, -B₂, -B₃, -B₄, -C, -D, -G, -H and -I. A mixture of the 10 saikosaponins was injected into the Ascentis^® Express C18 column (100 mm × 4.6 mm, 2.7 μm) with gradient elution and detection with CAD and ELSD by splitting. We examined various factors that could affect the sensitivity of the detectors including various concentrations of additives, pH and flow rate of the mobile phase, purity of nitrogen gas and the CAD range. The sensitivity was determined based on the signal-to-noise ratio. The best sensitivity for CAD was achieved with 0.1 mM ammonium acetate at pH 4.0 in the mobile phase with a flow rate of 1.0 mL/min, and the CAD range at 100 pA, whereas that for ELSD was achieved with 0.01% acetic acid in the mobile phase with a flow rate at 0.8 mL/min. The purity of the nitrogen gas had only minor effects on the sensitivities of both detectors. Finally, the sensitivity for CAD was two to six times better than that of ELSD. Taken together, these results suggest that CAD provides a more sensitive analysis of the 10 saikosaponins than does ELSD.     

Control of impurities in l-aspartic acid and l-alanine by high-performance liquid chromatography coupled with a corona charged aerosol detector

In this study a reversed phase ion-pair high-performance liquid chromatography (HPLC) method using charged aerosol detection (CAD) was developed and fully validated for the pharmaceutical quality control of l-aspartic acid (Asp). With a slight modification, the method also allows the evaluation of related substances in l-alanine (Ala). The method enables simultaneous control of related amino acids and of possibly occurring organic acids contaminants. A minimum limit of quantification of 0.03% could be achieved for all occurring related substances. Moreover, the detector sensitivity of the CAD was compared with an evaporative light scattering detector (ELSD). Depending on the analyte the CAD was found to be 3.6–42 times more sensitive than the ELSD. The HPLC method was applied to the purity testing of 8 samples of pharmaceutical grade and reagent grade Asp and of 12 samples of Ala supplied by various manufacturers. Both substances were found to be of high purity (greater than 99.8% for Asp and greater than 99.9% for Ala). Malic acid and Ala were the major impurities in Asp. Asp and glutamic acid (Glu) were the only detectable impurities in Ala.     

Determination of atracurium,cisatracurium and mivacurium with their impurities in pharmaceutical preparations by liquid chromatography with charged aerosol detection

The Corona CAD (charged aerosol detection) is a new type of detector introduced for LC applications that has recently become widely applied in pharmaceutical analysis. The Corona CAD measures a physical property of analyte and responds to almost all non-volatile species, independently of their nature and spectral or physicochemical properties. The LC method with charged aerosol detection was developed for the determination of three isomers of atracurium, cisatracurium and also three isomers of mivacurium with their impurities. The limit of quantitation for laudanosine was 1 μg ml⁻¹. The elaborate method for the analysis of those active substances and laudanosine proved to be fast, precise, accurate and sensitive. All other impurities were identified using time-of-flight mass spectrometry with electrospray ionization.     

Assessment of microcystin purity using charged aerosol detection

The increasing occurrence of toxic cyanobacterial blooms has led to a requirement for robust monitoring strategies and whilst several validated procedures have been developed these can be limited by the lack of high quality calibration standards. High quality standards must have confirmation of identity, purity and concentration by multiple methods. One aspect, purity, is rarely addressed but is essential. This is the first evaluation of the charged aerosol detector (CAD) to determine the benefits of incorporating a universal detector for more accurate purity determination of these peptides. Microcystins were detected at 5–10 ng on the column using the CAD, providing comparable quantification limits to those obtained using traditional UV detection. Purity determination of test compounds that had been partially purified, had showed that highest purity was at 238 nm > UV TIC > ESI TIC > CAD indicating that increased impurities could be detected using the CAD thus providing a more accurate indication of compound quality. Compounds purified by preparative HPLC were shown to have relative purities between 97% and 99%, however, when evaluated by CAD this dropped to 90–94% supporting the multi-detector strategy as essential for production of high quality compounds.     

求最大团的图分解算法

本文先建立关于图的边分解和顶点分解的一些定理，然后论述求图的最大团的几种算法:顶点分解、边分解的混合分解.最后举例说明边分解的算法.用FORTRAN语言编写的该算法的程序已在IBM-PC机上实现     

Presence of virgin olive oil phenolic metabolites in human low density lipoprotein fraction: determination by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry

The biological benefits of olive oil in preventing the oxidation of low density lipoprotein (LDL) would seem to be linked to its high monounsaturated fatty acid contents, but also to its respective phenolic compounds contents. One prerequisite to assess the in vivo physiological significance of phenolic compounds is to determine their presence in human LDL following the ingestion of virgin olive oil.In this work, olive oil phenolic metabolites were identified using high-performance liquid chromatography in tandem with electrospray mass spectrometry (HPLC-ESI-MS/MS) detection, after solid phase extraction (SPE). Quantitative methods were developed in carrying out linearity, precision, sensitivity and recovery tests. The results from two methods of LDL separation were compared and shorter LDL isolation procedure showed a better recovery for antioxidants compounds in LDL. The metabolites identified in LDL were: hydroxytyrosol monoglucuronide, hydroxytyrosol monosulfate, tyrosol glucuronide, tyrosol sulfate and homovanillic acid sulfate. The fact that olive oil phenolic metabolites are able to bind LDL strengthens claims that these compounds act as in vivo antioxidants.     

参数曲线近似弧长参数化的三角函数方法

本描述了一种局部的近似弧长参数化插值方法，用三角函数对曲线的弧长函数进行分段逼近，段与段之间是相互独立的，且插值曲线在插值点处的弧长与原参数曲线的真实弧长相等。