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.     

The a posteriori error estimates of Chebyshev–Petrov–Galerkin methods for second-order equations

In this paper, the a posteriori error estimates of Chebyshev–Petrov–Galerkin approximations are investigated. For simplicity, we choose the Poisson equation with Dirichlet boundary conditions to discuss the a posteriori error estimators, and deduce their efficient and reliable properties. Some numerical experiments are performed to verify the theoretical analysis for the a posteriori error estimators.     

KClO_4/Zr在石英管内的燃烧发射光谱与燃烧产物分析

为了研究燃烧条件对KClO_4/Zr烟火剂燃烧过程中光辐射性能的影响,考察了KClO_4/Zr在开放环境和不同规格封闭石英管内的燃烧发射光谱和燃烧产物。借助光纤光谱仪、光电二极管和示波器测试了烟火剂燃烧过程中的光辐射能量分布和闪光时间-强度曲线,分析了所得发射光谱在(590±10),(750±10)和(808±10)nm三个主吸收波段内的光谱效率,借助SEM表征了不同燃烧条件下KClO_4/Zr燃烧产物的形貌。结果表明:在开放条件下燃烧时,KClO_4/Zr的燃烧发射光谱在可见光到近红外的宽波段内,最强辐射出现在730~820nm波段。在石英管内封闭燃烧时,随着石英管体积的减少,在石英管外检测到的燃烧发射光谱强度逐渐减弱,光谱能量分布也呈现不同的变化规律,而且对火焰发射光谱分布进行处理后,随着石英管体积的变化,得到(590±10),(750±10)和(808±10)nm波段的光谱效率也呈现不同的变化规律。但是,随着石英管体积的减少,KClO_4/Zr烟火剂的爆燃闪光辐射时间逐渐缩短,峰值辐射强度逐渐提高。增加石英管的直径,有利于在管外获得更高的有效光辐射能量,减少石英管的直径,则有利于提高烟火剂的峰值辐射强度。随着管直径的增大,KClO_4燃烧更加充分,产物粒径较小,呈规则的球状。而管长度的改变对反应并无太大影响。     

Screening of exon methylation biomarkers for colorectal cancer via LC‐MS/MS strategy

The identification of biomarkers would be of benefit for the diagnosis and treatment of colorectal cancer. DNA methylation in specific genomic regions, which had shown strongly association with disease genotypes, was an effective indicator to reveal the occurrence and development of cancers. To screen out methylation biomarkers for colorectal cancer (CRC), genomic DNA was isolated from colorectal cancerous and corresponding cancer‐adjacent tissues collected from 30 CRC patients and then bisulfite‐converted. The exon regions of 5 targeted genes (CNRIP1 , HIC1 , RUNX3 , p15 , and SFRP2 ) were amplified by using nested polymerase chain reaction with specific primers, and the amplicon was purified and hydrolyzed. The methylation levels of these specific regions were detected by liquid chromatography tandem mass spectrometry (LC‐MS/MS). The results showed that 5 targeted exon regions were successfully amplified and confirmed by sequencing. The methodological validations indicated that LC‐MS/MS was highly sensitive and accurate. The methylation levels of CNRIP1 and RUNX3 were remarkably high in CRC tissues with statistical difference when compared with corresponding cancer‐adjacent individuals, while that of HIC1 , p15 , and SFRP2 had no difference between 2 subjects. These findings supported CNRIP1 and RUNX3 as potential DNA methylation biomarkers for CRC diagnosis and treatment, and our LC‐MS/MS approach exhibited great advantages in the identification of regional DNA methylation biomarkers.     

An active-set projected trust-region algorithm with limited memory BFGS technique for box-constrained nonsmooth equations

In this article, by means of an active set and limited memory strategy, we propose a trust-region method for box-constrained nonsmooth equations. The global convergence and the superlinear convergence are established under suitable conditions.     

晶硅太阳电池原位光老化及热致输运机理

为研究晶体硅太阳电池在标准模拟光条件下的输出特性变化规律和电池内部载流子输运特性,采用原位光老化技术对被测电池进行光照处理,按标准测试实验流程测量电池的伏安特性及光谱响应等参量,发现原位光老化后太阳电池伏安特性各项参量衰减,导致电池效率降低;短波段光谱响应微量下降,是由于原位光老化过程中电池表面产生极微量的面缺陷导致经过硅表面的微量载流子被复合;而长波段响应明显降低,是由于晶硅内大量体缺陷被激活导致长波载流子在经过硅材料内部时被复合.随后将光老化后电池退火并测量比对电池各项特性参量,结果表明,退火对光老化后电池内部深层体缺陷具有较好的修复功能,但对浅层面缺陷没有修复功能,最终造成电池伏安特性参量和光谱响应只得到部分恢复.     

Spectral characterization and biocidal activity of organotin(IV) (E)-3-[(2′,6′-dichlorophenylamido)]propenoates

Biocidal and spectroscopic aspects of organotin(IV) complexes with (E)-3-[(2′,6′-dichlorophenylamido)]propenoic acid are described with support of elemental analysis. IR, ¹H, ¹³C, ¹¹⁹Sn NMR and mass spectral data suggest that the ligand is bidentate, coordinating through oxygen atoms and that diorganotin(IV) complexes are six-coordinate. Triorganotin(IV) carboxylates exist as pentacoordinated trigonal bipyramidal complexes in the solid state and tetrahedral ones in solution. The complexes have been screened against bacteria, fungi and brine-shrimp larvae to assess their biological activity.     

An unprecedented tetranuclear Zn(ΙΙ) complex with an unsymmetric Salen-type bisoxime ligand: synthesis,crystal structure,and spectral properties

A tetranuclear Zn(ΙΙ) complex, [Zn₄L₂(OAc)₂(CH₃OH)₂] with an unsymmetric Salen-type bisoxime (H₃L?=?6-hydroxy-4′,6′-dibromo-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol), has been synthesized and structurally characterized. There are two kinds of coordination geometry (trigonal bipyramidal and square pyramidal) in the Zn(ΙΙ) complex. The molecule has serious distortion probably from the asymmetry. The complex exhibits blue emission with the maximum emission wavelength λ _max?=?423?nm when excited with 340?nm.     

Quantitative Structure-Toxicity Relationships Using Tops-Mode. 2. Neurotoxicity of a Non-Congeneric Series of Solvents

Abstract

Neurotoxicities of a series of solvents in rats and mice have been modeled by means of the TOPS-MODE approach. Two quantitative structure-toxicity relationship (QSTR) models were obtained explaining more than 80% of the variance in the experimental values of neurotoxicity of 45 solvents. Only one compound was detected as statistical outlier for these models. In contrast, previous models explained less than 60% of the variance in this property for 44 solvents. Finally, the contributions to neurotoxicity in rats and mice for a series of structural fragments were found. Structural characteristics of chlorinated fragments responsible for their different neurotoxicities were analyzed. The differences in neurotoxic behavior of some fragments in rats and mice were also analyzed, which could give insights on the toxicological mechanism of action of solvents studied.