Observations of trends for singular values and eigenvectors from library searching ultraviolet-visible spectra with spectral subtraction

A promising procedure for computerized library searching and identification of ultraviolet-visible spectra for one- and two-component mixtures is evaluated. The procedure is based on singular value decomposition and utilizes band position and shape. Searching more than one library spectrum at a time is possible. Library spectra which have similar spectra (collinear) with the sample and each other are indicated by two measures. First, a large condition index must be obtained, and second, two or more large variance-decomposition proportions in the same row need to be associated with the large condition index. The searching procedure has a significant degree of differentiation between the actual sample and potential candidates and is compared with the dot product, Euclidean distance and the correlation coefficient.     

A study for quality evaluation of Taxilli Herba from different hosts based on fingerprint-activity relationship modeling and multivariate statistical analysis

In this study, a fingerprint-activity relationship modeling between chemical fingerprints and antirheumatic activity was established, and multivariate statistical analysis was used to evaluate the quality of Taxilli Herba (TH) from different hosts. Characteristic fingerprints of 20 batches of TH samples were generated by high-performance liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (HPLC-Triple TOF-MS/MS), and the similarity analysis was calculated based on thirteen common characteristic peaks by hierarchical clustering analysis (HCA). Subsequently, nine efficacy markers were discovered by combining fingerprints and antirheumatic activity through grey correlation analysis (GCA) and bivariate correlation analysis (BCA). Meanwhile, the content of 5 constituents in 9 markers was determined by high-performance liquid chromatography coupled with triple quadrupole-linear ion trap tandem mass spectrometry (HPLC-QTRAP-MS/MS). The comprehensive quality of TH was assessed using multivariate statistical analysis, including principal components analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS). The results showed that a high dose of TH extract could markedly ameliorate arthritis damage compared to other doses, with flavonoids playing an important role in the antirheumatic activity. The comprehensive quality of samples from Morus alba L. (SS) was superior to those from Liquidambar formosana Hance (FXS). The present study will demonstrate the markers associated with efficacy, and provide an applicable strategy for more comprehensive quality control and evaluation of TH.     

高纯氧化钇中镧、铈、钐、铝、铅和铜的电感耦合等离子体原子发射光谱法测定

本文以纯Y_2O_3中杂质元素的ICP-AES测定为例,研究用数值微分技术解决光谱干扰同题。结果表明,导数光谱法不仅可以有效地消除来自基体的光谱干扰,还能减小谱线干扰对检测能力的影响。当分析物浓度较低时,导数光谱法的加入回收率明显优于离峰分析法,多数情况下也优于在峰法校正光谱干扰时的回收率。     

稠杂环化合物的研究（XV）──6－取代－3－（1H－苯并三唑－1－亚甲基）－1，2，4－三唑并［3，4－b］－1，3，4－噻二唑的合成

研究了３－（１Ｈ－苯并三唑－１－亚甲基）－４－氨基－５－巯基－１，２，４－三唑与取代苯甲酸在三氯氧磷催化下的反应，制得１０种新的３－（１Ｈ－苯并三唑－１－亚甲基）－１，２，４．三唑并［３，４－ｂ］－１，３，４－噻二唑，通过元素分析、ＩＲ、￣１ＮＭＲ和ＭＳ确证了它们的结构并讨论了其波谱性质。     

Synthesis and structural characterization of cobalt(II) and zinc(II) complexes with 2-(indazol-1-yl)-2-thiazoline (TnInA). X-ray characterization of [CoCl2(TnInA)2] · C2H6O and [(M)(TnInA)2(H2O)2](NO3)2 (M = Co, Zn)

Several complexes of 2-(indazol-1-yl)-2-thiazoline (TnInA) with the divalent ions Co and Zn have been synthesized by the direct combination of the ligand and the metal chloride or nitrate hydrated salts in ethanol. These complexes have been characterized by a variety of physical–chemical techniques. Moreover, the structures of [CoCl₂(TnInA)₂] · C₂H₆O (1) and [(M)(TnInA)₂(H₂O)₂](NO₃)₂ (M = Co, 3; Zn, 4) were determined by single-crystal X-ray diffraction. In all the complexes, the ligand TnInA bonds to the metal ion through the indazole and thiazoline nitrogen atoms. In complex 1 the environment around the cobalt ion may be described as a distorted octahedron with two TnInA ligands and two chlorine ligands. Compounds 3 and 4 are isostructural with a distorted octahedral geometry around the metal center, being linked to two water molecules and two TnInA ligands. However, in complex [ZnCl₂(TnInA)] (2) the zinc atom is four-coordinated with a probable tetrahedral environment with two chloro ligands and one TnInA ligand bonded to the metal ion.     

Non-destructive and clean prediction of aviation fuel characteristics through Fourier transform-Raman spectroscopy and multivariate calibration

The combination of Fourier transform (FT)-Raman spectroscopy and partial least squares (PLS) regression is proposed to be used in off-line kerosene quality control. Here, six important physico-chemical properties have been studied: Abel flash point, initial boiling point (IBP), 10% of distilled sample, final boiling point (FBP), total percentage of aromatic compounds (% aromatics) and viscosity. The Raman spectra were obtained directly from standard 2 ml glass vials ( mm), using a Bruker RFS 100 FT-Raman spectrometer, equipped with a 1064 nm Nd:YAG laser and a Ge detector, in back-scattering mode and accumulating 25 scans (150 s acquisition time) with a laser power of 300 mW. All Raman spectra were unit normalized in order to avoid the influence of the laser power into the regression models. Different Raman shift spectral ranges have been evaluated, the 193.5-1688.1 cm⁻¹ region being the most satisfactory one. Corrected standard errors of prediction of 1.9, 2.3, 2.8 °C, 0.19 cSt and 0.7% were obtained for flash point, IBP, FBP, viscosity and % aromatics, respectively. The influences of the glass vials, sample positioning and laser power have been studied, as well.     

Preparation of polyaniline‐sulfate salt ­by emulsion and aqueous ­polymerization pathway without using ­protonic acid

Aniline was polymerized directly into polyaniline‐sulfate salt without using protonic acid in this work. Polyaniline‐sulfate salt was prepared by emulsion and aqueous polymerization pathways. The dopant i.e. sulfate ion in polyaniline‐sulfate salt was generated from ammonium persulfate which was used for oxidizing aniline. Ammonium persulfate acts both as oxidizing agent as well as protonating agent in the polymerization process of aniline to polyaniline salt. The efficiency of oxidizing and protonating power of ammonium persulfate is increased by the use of surfactant. The activity of ammonium persulfate is further increased by the use of sulfuric acid as protonic acid. It may be necessary to consider the effect of sulfate ion which is generated during the oxidation process of aniline in the chemical polymerization of aniline to polyaniline salt by ammonium persulfate either aqueous or emulsion polymerization pathway in the presence of protonic acid/functionalized protonic acid. Copyright © 2001 John Wiley & Sons, Ltd.     

Hyphenation of column liquid chromatography and Raman spectroscopy via a liquid-core waveguide: chemometrical elimination of spectral eluent background

In column liquid chromatography (LC) coupled to conventional Raman spectroscopy (RS) removal of the spectral background of the eluent is often demanding, because of the strong signals of the organic modifier. A new chemometrical method is proposed, called the eluent background subtraction (EBS) method, which can correct for small shape and intensity differences of the eluent spectra. The variations in the eluent spectra are modelled using principal component analysis (PCA). The PCA loading vectors are subsequently used for eluent background correction of the elution spectra of the analyte. The loading vectors are fitted under these spectra by an asymmetric least-squares method. This method was successfully applied under various experimental conditions and performed much better than conventional background correction methods. Analyte detectability was improved by (weighted) averaging of all elution spectra and smoothing via a p-spline function.     

基于模糊聚类分析的织物质量分级方法

织物性能的分类、分级信息是纺织品质量评估的直观表述。在织物客观评估的基础上，提出了基于减法聚类与模糊C-均值(FCM)聚类的集成方法用于纺织品质量评估分析。该方法以减法聚类算法得出的样本的最佳分类数为基础，用FCM聚类算法得到具体的分类结果。将聚类中心的特征值之和定义为分级指数，进一步用于解决织物质量的分级问题。通过对法国鲁贝高等纺织工程学院自织的43块棉针织物的分析，证明了以上方法在处理纺织品质量分类、分级问题中的有效性。     

一种基于时序分析的大型重载支承轴隐蔽部位疲劳裂纹诊断方法

大型重载支承轴隐蔽部位因发生不可观测的突发性疲劳断裂事故,严重影响生产的正常进行,给企业带来重大的经济损失.在分析支承轴振动特性的基础上,通过在机械结构外部便于检测部位提取反映结构疲劳裂纹状态的特征信号,编写相应的MAT-LAB程序构建时序模型,然后模拟支承轴实际工况,将裂纹产生、发展、断裂过程划分为5种状态,建立标准故障模式特征向量空间.运用模糊聚类分析方法,结合Euclide距离判别函数,找出与标准故障模式特征向量中隶属度最大的特征向量,从而有效诊断支承轴隐蔽部位疲劳裂纹状态的程度.最后通过实例验证了该方法的正确性和可行性.图2,参5.