响应面法优化萃取条件用于高效液相色谱分析饮用水中痕量邻苯二甲酸二(2-乙基己基)酯及其迁移规律

应用响应面法辅助分析塑料瓶装饮用水中邻苯二甲酸二（2-乙基己基）酯（DEHP）的迁移,建立了一种快速、简便、环保的痕量塑化剂类污染物检测方法。在盐析作用下,使用正己烷涡旋萃取,经氮气浓缩后进行高效液相色谱-紫外检测。响应面最优分析法考察了盐量、涡旋时间和萃取液体积3个因素作为萃取条件对DEHP回收率的影响,得到最佳萃取条件：盐量为16 g/L、涡旋时间为90 s、萃取液体积为5.28 mL。在此实验条件下,DEHP的最大理论回收率为92.91%,实验验证值为92.97%,与理论值相差0.06%。本方法检出限为0.006 mg/L,满足中国国家标准规定的生活饮用水安全标准要求（0.008 mg/L）,在0.01~15 mg/L范围内线性关系良好（相关系数R=0.9996）。选取常见市售饮用水样品进行分析,研究了塑料包装饮用水中痕量DEHP迁移的规律。与传统的优化方法相比,响应面模型分析法综合考虑了各因素的影响,而且更加简便、低成本、对环境友好,是实现样品中微痕量污染物精准检测的重要辅助手段。     

Ultrasound-assisted extraction of functional compound from mulberry (Morus alba L.) leaf using response surface methodology and effect of microencapsulation by spray drying on quality of optimized extract

This study aimed to optimize the ultrasound-assisted extraction (UAE) condition of mulberry leaf extract (MLE) using response surface methodology and to microencapsulate MLE by spray drying using different coating materials and ratios of coating material and MLE. The extraction results showed that MLE from condition of 60 °C (X₁, temperature), 30 min (X₂, time) and 60% v/v (X₃, ethanol concentration) exhibited the highest bioactive compound and antioxidant activity (DPPH and FRAP assay). Based on this optimal condition, MLE was further encapsulated by spray drying. It was found that MLE encapsulated with resistant maltodextrin at ratio of MLE and resistant maltodextrin 1:1 (w/w) showed the highest encapsulation yield (%) and encapsulation efficiency (%). Water solubility, moisture content and water activity were non-significant (p > 0.05) among the microcapsules. The scanning electron microscope (SEM) revealed that the types of coating material affected their microstructures and microcapsules prepared by resistant maltodextrin as coating material had a spherical shape, smooth surface and less shrinkage than microcapsules prepared by maltodextrin and gum arabic which had rough surfaces. The highest antioxidant activity was obtained from microcapsule prepared by gum arabic at ratio of MLE and gam arabic 1:2 (w/w). In conclusion, optimal condition from UAE and encapsulation by spray drying suggest the critical potential for production of functional food with improved bioactive compound stability and maximized antioxidant activity.     

Composition and antioxidant activity of anthocyanins from Aronia melanocarpa extracted using an ultrasonic-microwave-assisted natural deep eutectic solvent extraction method

A time-saving, efficient, and environmentally friendly ultrasonic-microwave-assisted natural deep eutectic solvent (UMAE-NADES) extraction method was developed for the extraction of anthocyanins from Aronia melanocarpa. Eight different natural eutectic solvents were screened initially, and choline chloride-glycerol was selected as the extraction solvent. The extraction conditions were optimized using the response surface methodology, and the extraction rate of anthocyanins was higher than those achieved using the traditional ethanol method, natural deep eutectic solvent extraction method, and ultrasonic-microwave-assisted ethanol method. Six anthocyanins, including cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, cyanidin-3-O-xyloside, cyanidin-3,5-O-dihexoside, and the dimer of cyanidin-hexoside were identified and extracted at a purity of 448.873 mg/g using high performance liquid chromatography-mass spectrometry (HPLC-MS). The compounds extracted using UMAE-NADES had higher antioxidant capacities than those extracted by the other three methods. The UMAE-NADES demonstrated significant efficiency toward the extraction of bioactive substances and has potential utility in the food and pharmaceutical industries.     

Palladium‐Catalyzed N‐Alkylation of Amides and Amines with Alcohols Employing the Aerobic Relay Race Methodology

Possibly because homogeneous palladium catalysts are not typical borrowing hydrogen catalysts and ligands are thus ineffective in catalyst activation under conventional anaerobic conditions, they had not been used in the N‐alkylation reactions of amines/amides with alcohols in the past. By employing the aerobic relay race methodology with Pd‐catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand‐free homogeneous palladiums are successfully used as active catalysts in the dehydrative N‐alkylation reactions, giving high yields and selectivities of the alkylated amides and amines. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed.     

结构优化中的建模方法概述

建立优化模型是结构优化前的最佳选择. 由于工程实际问题的复杂性, 很难建立显式表达的模型, 即使少数问题能够建立显式表达的模型, 也难以求解. 因此需要借助近似方法建立模型, 为了便于求解或提高求解效率, 通常还要对模型进行变换. 文中列举了结构优化中常用的近似建模方法, 并根据建立近似显式的途径和敏度分析的方法对其进行分类, 详细介绍了近几年来广泛应用的样本点构造方法, 然后描述了它们在结构优化中的应用和具体实现过程, 分析了它们的优缺点和应用范围, 指出了结构优化建模方法今后的发展方向.      

First Total Synthesis of Cleroindicin B,(±) Cleroindicin C and E

The isolation of cleroindicins B, C and cleroindicin E, together with three novel related compounds cleroindicins A, D and F, from chinese folk medicine Clerodendrum indicum Linn. was reported before1. Pharmaceutical studies showed that cleroindicin C has certain anticancer activity, so its total synthesis attracted our considerable interest.Cleroindicin B Cleroindicin C Cleroindicin EThe commercially available 2-(p-methoxyphenyl) ethanol 1 was selected as the starting material. Compound…     

田口方法和双重曲面响应(DRSM)法

田口参数设计在理论界遭到较多批评 ,也提出一些替代方法。双曲面响应 ( DRSM)法是结合田口参数设计的思想和统计回归模型发展起来的。本文通过正交旋转设计和计算机模拟噪声因子变化来提高双曲面响应法的精度并对两种方法应用结果进行比较 ,说明田口参数设计仍具有实践和方法论的启发意义     

Alternatives to a Semi-Parametric Estimator of Parameters of Rare Events—The Jackknife Methodology*

In this paper, and in a context of regularly varying tails, we propose different alternatives to a well-known estimator of the tail index—the Hill estimator (Hill, 1975). These alternatives have essentially in mind a reduction in bias, preferably without increasing Mean Square Error, by the use of suitable Generalized Jackknife methodologies (Gray and Schucany, 1972). The first estimate obtained through this methodolgy is the one introduced by Peng (1998), under a different context. Other Generalized Jackknife estimators are linear combinations of Hill estimators at different levels. This methodology of affine combinations of Hill estimators at different levels may be easily generalized to other semi-parametric estimators of the tail index, like Pickands' estimator (Pickands, 1975) or the Moment's estimator (Dekkers et al., 1989), and consequently to a general real tail index, seeming to be a promising field of research.     

On the Decay Rates of Buffers in Continuous Flow Lines

Consider a tandem system of machines separated by infinitely large buffers. The machines process a continuous flow of products, possibly at different speeds. The life and repair times of the machines are assumed to be exponential. We claim that the overflow probability of each buffer has an exponential decay, and provide an algorithm to determine the exact decay rates in terms of the speeds and the failure and repair rates of the machines. These decay rates provide useful qualitative insight into the behavior of the flow line. In the derivation of the algorithm we use the theory of Large Deviations.     

对称迭层矩形板的平面应力分析

常用的对称迭层板为各向异性板．根据平面应力问题的基本方程精确地用应力函数解法求得了各向异性板的一般解析解．推导出平面内应力和位移的一般公式,其中积分常数由边界条件来决定．一般解包括三角函数和双曲函数组成的解,它能满足4个边为任意边界条件的问题．还有代数多项式解,它能满足4个角的边界条件．因此一般解可用以求解任意边界条件下的平面应力问题．以4边承受均匀法向和切向载荷以及非均匀法向载荷的对称迭层方板为例,进行了计算和分析．