Dose-effect study on the antioxidant properties of leaves and outer bracts of extracts obtained from Violetto di Toscana artichoke

Artichoke (Cynara scolymus L.) is an edible vegetable largely used in the Mediterranean diet and in folk medicine. The present paper discusses the analysis of the polyphenol content of leaves and outer bracts of Violetto di Toscana artichoke using different extraction procedures with the aim of establishing a correlation between polyphenol subclasses and antioxidant activity measured on human LDL oxidized by copper ions. HPLC/DAD and HPLC/MS analyses revealed that both the matrixes contain identical polyphenol subclasses, with mainly quantitative differences. The antioxidant effect of four artichoke extracts decreases in the following order when the sum of total phenolic compounds was considered: ethanolic extract from leaves (IC₅₀ = 2.92 ± 0.46 μM); ethanolic extract from outer bracts (IC₅₀ = 4.04 ± 0.21 μM); ethyl acetate extract from leaves (IC₅₀ = 4.91 ± 0.11 μM); ethyl acetate extract from outer bracts (IC₅₀ = 10.18 ± 1.6 μM). IC₅₀ were also calculated considering the concentrations of single polyphenol subclasses. In both cases, the potency of antioxidant properties was not related to the amount of total polyphenols or the single subclasses.     

Characterization and fractionation of phenolic compounds extracted from olive oil mill wastewaters

Liquid–liquid extraction was used in order to recover phenolic compounds from olive mill wastewater (OMWW), a polluting by-product of olive oil production process, and the extraction parameters have been optimized. HPLC analysis showed that hydroxytyrosol is the most abundant biophenol in ethyl acetate extracts from an acidified OMWW. Many other biophenols (tyrosol, caffeic acid, vanillic acid, verbascoside, luteolin-7-glucoside, dialdehydic form of decarboxymethyl oleuropein aglycon, ligstroside, luteolin) were identified.     

数据降维方法分析与研究 *

全面总结现有的数据降维方法,对具有代表性的降维方法进行了系统分类,详细地阐述了典型的降维 方法,并从算法的时间复杂度和优缺点两方面对这些算法进行了深入的分析和比较。最后提出了数据降维中仍 待解决的问题。     

一种半监督局部线性嵌入算法的文本分类方法*

针对局部线性嵌入算法（LLE）应用于非监督机器学习中的缺陷,将该算法与半监督思想相结合,提出了一种基于半监督局部线性嵌入算法的文本分类方法。通过使用文本数据的流形结构和少量的标签样本,将LLE中的距离矩阵采用分段形式进行调整;使用调整后的矩阵进行线性重建从而实现数据降维;针对半监督LLE中使用欧氏距离的缺点,采用高斯核函数将欧氏距离进行变换,并用新的核距离取代欧氏距离,提出了基于核的半监督局部线性嵌入算法;最后通过仿真实验验证了改进算法的有效性。     

甲基丙烯酸甲酯-对二甲苯-水体系的盐效应

在４０℃的条件下，研究了甲基丙烯酸甲酯－对二甲苯－水体系的盐效应。试验结果表明硫酸氢铵对该体系的ＭＭＡ产生盐析效应。用Ｅｉｓｅｎ－Ｊｏｆｆｅ方程对该含盐体系的ＬＬＥ数据进行关联，关联的值与试验值符合得较好。     

甲基环己烷－苯－DMF－水液液平衡的研究

采用作者设计的液液平衡釜，于常压下测定了甲基环己烷（１）－ＤＭＦ（２）二元系（２０．０～４７．９℃）的互溶度数据，以及常压、２０．Ｏ℃和３５．Ｏ℃下甲基环己烷（１）－苯（２）－ＤＭＦ（３）三元系和甲基环己烷（１）－苯（２）－ＤＭＦ（３）－水（４）（ＤＭＦ／Ｈ２Ｏ＝４∶１，ｍａｓｓ比）四元系的ＬＬＥ数据。     

Molecular thermodynamics approach on phase equilibria of dendritic polymer systems

We suggest a molecular thermodynamic framework to describe the phase behavior of dendritic polymer systems. The proposed model, which is based on the lattice cluster theory, contains correlations of molecular structure and specific interactions such as hydrogen bonding to the phase equilibria of branch-structured polymer systems. We examine liquid-liquid equilibria (LLE) of hyperbranched polymer solutions and vapor-liquid equilibria (VLE) of dendrimer solutions in the viewpoints of effects of a branched structure and specific interaction formations among endgroups of dendritic polymer and solvent molecules. We investigate VLE of dendrimer/solvent (Benzyl Ether Dendrimer/Toluene) systems by the combination of a new lattice-based model and atomistic simulation technique. The interaction energy parameters are obtained by the pairs method [Baschnagel et al., 1991] including Monte Carlo simulation with excluded volume constraint. In the pairs method [Baschnagel et al., 1991], we do not simulate the whole molecule as in molecular dynamics or molecular mechanics, but only monomer segments interacting with solvent molecules. The proposed model shows improvements in prediction for both phase equilibria (VLE and LLE) due to the branched structure and specific interaction due to endgroups at periphery of dendritic polymer molecule. Atomic simulation technique gives good result in prediction without fitting variables. Our results show that the specific interactions between the endgroup and the solvent molecule play an important role in phase behavior of the given systems.     

一种新的有监督流形学习方法

提出了一种新的有监督流形学习方法,目的是提供将流形学习降维方法高效应用于有监督学习问题的全新策略.算法的核心思想是集成流形学习方法对高维流形结构数据的降维有效性与支撑向量机(SVM)在中小规模分类数据集上的优良特性实现高效有监督流形学习.算法具体实现步骤为:首先利用SVM在流形学习降维数据中选出对分类决策最重要的数据集,即支撑向量集;按标号返回可得到原空间的支撑向量集;在这个集合上再次使用SVM即可得到原空间的分类决策,从而完成有监督流形学习.在一系列人工与实际数据集上的实验验证了方法的有效性.     

磷酸三丁酯-水-磷酸体系液液相平衡研究

测定了磷酸三丁酯－水－磷酸三元体系在２５℃和５０℃下的液液相平衡数据．应用Ｐｉｔｉｅｒ电解质溶液理论和Ｇｕｇｇｅｎｈｅｉｍ似晶格非电解质溶液理论,提出了该体系中有机相组分活度系数的计算方法,在关联出计算所需的模型参数的基础上,计算了该体系在２５℃下的活度系数值。     

流形学习方法中的若干问题分析

流形学习是近年来机器学习与认知科学中的一个新的研究热点,其本质在于根据有限的离散样本学习和发现嵌入在高维空间中的低维光滑流形,从而揭示隐藏在高维数据中的内在低维结构,以实现非线性降维或者可视化.介绍了几种主要的流形学习算法,分析了它们的优势与不足,总结了流形学习方法中需要解决的若干问题及其研究现状,并展望了流形学习未来的研究前景.