质谱法在法庭科学领域新精神活性物质检验中的应用综述

近年来,新精神活性物质(NPS)的使用已成为一个严重的全球性问题,不仅对人类的身体健康造成危害,同时其引起的社会问题和潜在危机不可估量.因此,检验不同环境下不同种类的新精神活性物质迫在眉睫.本文对近几年来国内外采用质谱法检验新精神活性物质的文献进行了综述,主要介绍了两种质谱法:气相色谱-质谱法(GC/MS)和液相色谱-...     

GC-MS法同时测定橡皮擦中22种邻苯二甲酸酯增塑剂

建立了气相色谱-质谱(GC-MS)分段选择离子监测(SIM)模式分析同时测定橡皮擦中22种邻苯二甲酸酯(PAEs)增塑剂含量的方法。该方法具有良好线性,相关系数R均大于0.999,检测限在1.3 mg/kg～128.9 mg/kg之间,平均回收率在70.2%～105.6%,相对标准偏差在2.57%～9.88%之间。通过该方法对国内橡皮擦中PAEs增塑剂进行检测,实际样品均检出邻苯二甲酸二(2-乙基)己酯(DEHP),含量最高达32.5%。     

黎蒴栲木片苯／醇提取物成分的GC-MS分析

将通过混合有机溶剂提取法从新鲜黎蒴栲木片中获得的苯，醇提取物，经浓缩，利用气相色谱-质谱（GC-MS）分析，采用色谱峰面积归一化法计算各组分的相对含量。该提取物共分离出53个峰，并从中鉴定出32个化合物，占总峰面积的86．33％，其主要成分及含量为：丁二酸甲基-二丁酯（cas）（15．17％）、1,2-邻苯二甲酸二异辛酯（14．71％）、乙二酸双（2-甲丙基）酯（cas）（14．21％）、1，2-邻苯二甲酸双（2-甲丙基）酯（cas）（10．23％）、邻苯二甲酸二丁酯（5．22％）、4，4，6a，6b，8a，11，11，14b-八甲基-1,4，4a,5，6，6a，6b，7，8，8a,9，10，11，12，12a，14，14a，14b-十八氢-2H-picen-3-酮（4．09％）、á-桉叶油醇（3．88％）、丁二酸双（2-甲丙基）酯（3．64％）、4-（3．羟基-1-丙烯基）-2-甲氧基-苯酚（cas）（2．11％）、己二酸二辛酯（cas）（1．84％）、十六酸乙酯（cas）（1.23％）、咖啡碱（1．20％）、2-异丙基-1-甲基萘（1．01％）、10-甲基三环[4，3，1，1（2，5）]十一醛-10-醇（1．01％）。首次报道了黎蒴栲木片苯／醇提取物的化学成分，为开发利用黎蒴栲木片苯僻浸提废液和实现清洁生产提供了科学依据．     

An application of chemometric techniques to analyze the effects of the wave function modifications on the intermolecular stretching frequencies of the hydrogen-bonded complexes

Factorial design and principal component models are used to determine how ab initio H-bond stretching frequencies depend on characteristics of the molecular orbital wave functions of acetylene–HX, ethylene–HX and cyclopropane–HX π-type hydrogen complexes with X=F, Cl, CN, NC and CCH. The results obtained for the three sets of complexes show that factorial design and principal component analyses complement each other. Factorial design calculations clearly show that these frequencies are affected mostly by inclusion of electron correlation on the calculation level. On average, their values are increased by about 25 cm⁻¹ due to a change from the Hartree–Fock (HF) to Möller–Plesset 2 (MP2) level. Valence, diffuse and polarization main effects as well as valence–diffuse, diffuse–correlation and polarization–correlation interaction effects are also important to better describe a factorial model to the H-bond stretching frequencies of these hydrogen complexes. This simplified model has been successful in reproducing the complete ab initio results, which correspond to two hundred and forty calculations. Principal component analyses applied only to hydrogen-bonded complexes whose experimental frequencies are known, has revealed that the six-dimensional original space can be accurately represented by a bidimensional space defined by two principal components. Its graphical representation reveals that the experimental intermolecular stretching frequencies are in closest agreement with the MP2/6–31+G and MP2/6–311+G ab initio results.     

A discussion of objective function representation methods in global optimization

Non-convex optimization can be found in several smart manufacturing systems. This paper presents a short review on global optimization (GO) methods. We examine decomposition techniques and classify GO problems on the basis of objective function representation and decomposition techniques. We then explain Kolmogorov’s superposition and its application in GO. Finally, we conclude the paper by exploring the importance of objective function representation in integrated artificial intelligence, optimization, and decision support systems in smart manufacturing and Industry 4.0.     

On the equivalence of optimality criterion and sequential approximate optimization methods in the classical topology layout problem

We study the ‘classical’ topology optimization problem, in which minimum compliance is sought, subject to linear constraints. Using a dual statement, we propose two separable and strictly convex subproblems for use in sequential approximate optimization (SAO) algorithms. Respectively, the subproblems use reciprocal and exponential intermediate variables in approximating the non‐linear compliance objective function. Any number of linear constraints (or linearly approximated constraints) are provided for. The relationships between the primal variables and the dual variables are found in analytical form. For the special case when only a single linear constraint on volume is present, we note that application of the ever‐popular optimality criterion (OC) method to the topology optimization problem, combined with arbitrary values for the heuristic numerical damping factor η proposed by Bendsøe, results in an updating scheme for the design variables that is identical to the application of a rudimentary dual SAO algorithm, in which the subproblems are based on exponential intermediate variables. What is more, we show that the popular choice for the damping factor η=0.5 is identical to the use of SAO with reciprocal intervening variables. Finally, computational experiments reveal that subproblems based on exponential intervening variables result in improved efficiency and accuracy, when compared to SAO subproblems based on reciprocal intermediate variables (and hence, the heuristic topology OC method hitherto used). This is attributed to the fact that a different exponent is computed for each design variable in the two‐point exponential approximation we have used, using gradient information at the previously visited point. Copyright © 2007 John Wiley & Sons, Ltd.     

Low‐frequency assessment of the in situ acoustic absorption of materials in rooms: an inverse problem approach using evolutionary optimization

The in situ assessment of the acoustic absorption of materials is often a necessity. The need to cover the whole frequency range of interest for the building engineer has led the authors to an approach involving two frequency‐complementary measurement methods. This paper deals with the part dedicated to low frequencies. The measurement is defined here as a boundary inverse interior problem. A numerical model of the room under investigation, allowing for the computation of the pressure field in the volume, given impedance boundary conditions and a point source, is combined to a global optimization algorithm. The algorithm explores the set of possible boundary conditions in order to minimize the difference between the computed pressure values and the one observed at a few measurement points, leading to the determination of all the boundary conditions at a time. In practice, the finite element method (FEM) or the finite difference method (FDM) is used here to model the room and an Evolution Strategy as the optimization tool. After describing the ES operators, a numerical study is carried out on simulated measurements, both on problem‐ and algorithm‐specific parameters, in the case of an academic two‐dimensional room geometry. The method is then applied to a three‐dimensional room with promising results. Copyright © 2002 John Wiley & Sons, Ltd.