Phenolic potential of Tannat, Cabernet-Sauvignon and Merlot grapes and their correspondence with wine composition

The phenolic potential of Tannat, Cabernet-Sauvignon and Merlot grapes was evaluated in 2001 and 2002 and its correspondence with the colour and composition of the respective wines was established. Three vineyards of each variety, situated in the south of Uruguay were considered. Two samples of each vineyard were taken at the moment of the harvest. Phenolic richness, extractable anthocyanins contents and total potential in anthocyanins of the grapes were estimated. Two fermentations on skins were carried out for each vineyard using 50 kg of grape in each one. The anthocyanic and total polyphenols contents of the musts were analysed every 24 h, and skins extractions were carried out in parallel in the laboratory. The duration of the maceration for each variety was decided in function of the analytical results in the grapes, musts and skins extractions. Wines were analysed 2 months after the alcoholic fermentation, determining its phenolic composition and colour. Tannat grapes presented anthocyanic and total polyphenols contents significantly higher in both years. Therefore, wines from this variety presented colour intensity and phenolic contents statistically higher than Cabernet-Sauvignon and Merlot. The correlations between the phenolic contents of the grapes, skins, musts and wines were very significant. Colour intensity and phenolic contents of the wines were highly correlated with the total polyphenols of the grapes and with anthocyanins of the grapes, skins, musts and wines. The estimate of the phenolic potential of the grapes and the extractability of the pigments allows to manage more adequately the fermentation on skins and is an interesting tool to predict the colour and the composition of the wines.     

Contributions to the Chemistry of the Binary Compounds of the Transition Elements

Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given.     

纳米粒子的精准组装

纳米材料由于其独特的光、电、磁、力学等性质,成为了构建功能材料与器件的理想基元。实现纳米粒子的精确组装,是探究粒子之间的耦合聚集性质和制备宏观功能器件的基础。但是由于纳米粒子的小尺寸以及在溶液中运动的随机性与复杂性,精准控制纳米粒子组装体的形貌以及在空间中的相对位置仍存在巨大挑战。为了将纳米粒子组装成理想的有序结构,许多控制粒子组装的策略与方法得到发展。本文首先概述了纳米粒子自组装的控制方法与典型形貌,着重分析了影响粒子精准排布的因素与控制方法,并对纳米粒子及其组装体的光学性质与器件应用的最新研究进展进行了讨论,最后对目前纳米粒子精准组装所面临的挑战以及未来发展的方向进行了展望。     

Reaction cells and collision cells for ICP-MS: a tutorial review

This paper reviews the literature published to September 2001 relating to the history, design, operation and application of linear radio-frequency (r.f.)-driven multipole collision cells and reaction cells in combination with inductively coupled plasma mass spectrometry. The available material is supplemented with original experimental data that demonstrates the principles presented. The relation of these devices to collision cells for organic mass spectrometry and to the three-dimensional ion trap is discussed in its historical context. A general tutorial on the fundamentals of ion collision and reaction, including thermochemistry, energy transfer and reaction kinetics, is given. Consideration is given to some of the fundamental aspects of operation and design of linear r.f. devices. This historical and fundamental framework then allows the tutorial to focus on the promotion and control of ion–molecule chemistry in linear r.f.-multipole cells for elemental analysis. Vacuum requirements are considered in some detail, and deal in particular with the issue of contamination of the reaction gas. Special attention is paid to the thermal characteristics of the ions in the cell, as this has important implications for the application of the available databases of thermochemical and thermal kinetic data to the development of analytical methods. Calculation and experimental validation of the efficiency of the ion–molecule chemistry leads to the recognition that secondary, sequential chemistry can play a limiting role in the realization of the potential of the cell method. The two principal means of controlling the analytical impact of the secondary chemistry, through post-cell kinetic energy discrimination and through in-cell mass-bandpassing are discussed and contrasted through spectral data acquired for different reaction gas types and pressures. The available literature on the application of collision cells and reaction cells for the analysis of samples of high purity, environmental, geological and biological materials is critically reviewed.     

Bond energies and the enthalpies of formation of mono- and polyradicals in nitroalkanes 2. Nitro derivatives of ethane and propane

Based on the experimental results and the published data, the enthalpies of formation of ethane and propane nitro derivatives were obtained for both the standard state and gas phase. The bond dissociation energies of the ethane and propane nitro derivatives were calculated using the enthalpies of atomization and the energies of nonvalent interactions of nitro groups. The calculated values were compared with the kinetic data on thermal decomposition. The bond dissociation energies in radicals of the ethane and propane nitro derivatives were also calculated using the enthalpies of atomization and the energies of nonvalent interactions of nitro groups. Regularities of changes in the bond dissociation energies of the ethane and propane nitro derivatives and their radicals were established.     

Physico-chemical factors governing partition behaviour of solutes and particles in aqueous polymeric biphasic systems. III. Features of solutes and biological particles detected by the partition technique

The partition behaviour of human serum albumin and oxyhaemoglobin and several amino acids and small peptides was studied in the aqueous Ficoll-dextran biphasic system as a function of the ionic composition and pH. The partition coefficients of the solutes were expressed in terms of the equivalent number of CH2 groups, nCH2, and the equivalent number of carboxyl groups, m. The physical meaning of these two parameters and of the relationships found between them and pH for the proteins examined are discussed. A correlation was established between the difference in the relative hydrophobicities of the individual phases of various water-organic solvent systems and the interfacial tension, gamma 12, of the systems. It is argued that a relation of a similar type exists for the aqueous polymeric biphasic systems. The possibility of estimating the relative intensity of Van der Waals and hydration interactions of a solute and particle surface by examination of their partitioning in a biphasic system calibrated for the hydrophobic and hydration properties of the phases is discussed.     

The use of analysis of covariance to assess repeatability in electrode performance

The repeatability of a K(+)-selective glass electrode and a Cu(2+)-selective solid-state electrode was assessed by the determination of the variation of the slope and potentials in successive calibrations, and by analysis of covariance of the regression lines of potential vs. logarithm of ion activity. When assessed by any one of these three methods, both electrodes displayed high repeatability in most of the calibration sets. However, in several calibrations, the variation of the slope and potential was low, but the regression lines were statistically different. In no case was the variation of the slope and potential high and the regressions not statistically different. The results suggested that analysis of covariance can be used to test electrode repeatability, and provides a more restricted evaluation of this parameter than the variation of the slope and potential. The characteristics of analysis of covariance suggest that it provides an objective and rigorous test for electrode repeatability. The advantages of the use of analysis of covariance over the determination of the variation of the slope and potential are listed.     

燃烧过程中碱/碱土金属对重金属迁移转化影响的研究进展

碱/碱土金属广泛存在于各种固体燃料中，在燃烧过程中碱/碱土金属与燃料中重金属及其他矿物发生复杂的物理化学反应，从而影响重金属的迁移和转化。本研究主要介绍了碱/碱土金属对As、Se、Pb和Cr四种重金属迁移转化的影响规律，包括碱金属和碱土金属对重金属迁移转化的影响，颗粒物团聚与黏结对重金属排放的影响三个方面。碱/碱土金属能够抑制重金属的挥发：碱金属与Cl元素的结合，降低了PbCl₂的生成；碱金属的存在有利于提升高岭土对Pb的吸附效率；碱/碱土金属可以与As和Se形成稳定的化合物。但同时需要注意碱/碱土金属与Cr的部分结合产物中，Cr以六价态存在，具有较高的毒性。碱/碱土金属对于团聚现象发生，分别起到了促进和抑制作用，适当含量的碱金属有利于减少重金属的释放。通过总结碱/碱土金属对重金属迁移转化的影响规律，以期为降低重金属的危害提供思路。     

过渡金属改性MCM-41的结构及对苯催化氧化的研究

制备了Ti,Fe,Cr,Ni改性的MCM-41,采用XRD、低温N₂吸附及TPD手段研究了改性MCM-41的结构特征和表面性质.过渡金属可同品取代骨架Si,同品取代的能力与过渡金属离子半径有关.过渡金属改性MCM-41均具有较好的长程有序结构、均一的孔径分布和较高的比表面积.引入不同的过渡金属可以改变MCM-41表面酸性和亲水/憎水性.考察了改性MCM-41对苯氧化的催化性能.     

中药指纹图谱学体系在中药创制中的作用

从整体论、系统论和复杂科学的角度论述了中药指纹图谱学体系的构成背景和核心任务。中药指纹图谱学体系具有体系科学性质,是从系统性和整体性角度研究中药(包括植物药)的物质基础和作用机制以及药代动力学规律和相关制剂技术的崭新学科。该体系以中药指纹图谱信息学为核心和桥梁,包括中药指纹图谱测试学、中药指纹图谱质控学、中药指纹图谱谱效学、中药指纹药物动力学、中药指纹药剂学和中药生物指纹图谱学。该体系的研究需采用复杂科学和体系科学的理论和方法,突破线性思维和还原分析,强调宏观和系统的有机综合,应用数学科学原理和方法来开辟中药创制的新模式。中药指纹图谱学的理论体系和方法是解析中药的主导技术和实现中药现代化的核心力量,该体系理论和技术的成熟及完善可为现代中药创制提供强有力的理论和技术支撑。中药指纹图谱学体系的最终目的是为人类和有益生物研制出疗效显著、安全、可控的现代化中药。     

Matrix effects of easily ionizable elements and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry

Matrix effects of Na, Ca and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry were investigated with a number of atomic and ionic lines covering a wide range of energies. The plasma was sustained in an Okamoto cavity at atmospheric pressure by using nitrogen as the plasma gas as well as the nebulizer gas. Most of the atomic lines tested exhibited enhancement effects and all of the ionic lines gave suppression effects in the presence of Na and Ca. The effects decreased with increasing microwave power. There was good correlation between matrix effects, the excitation energy and energy sum of the spectral lines. The lower the excitation energy for atomic lines and the higher the energy sum for ionic lines, the stronger the matrix effects. Unlike Na and Ca, nitric acid showed suppression effect for all of the spectral lines and the effect was independent of the energy of the spectral lines and the microwave power. The effect of matrix on the excitation temperature and the electron number density was measured and the mechanism of matrix effect was discussed.     

Calculations of the distribution of trace impurities in cylindrical pores

The equilibrium distribution of a trace impurity and the self-diffusion coefficients of molecules of the base component and the trace impurity in narrow cylindrical pores were calculated using the lattice-gas model. Two types of lattice structures with six and eight closest neighbors were considered. The sizes of the base component and impurity molecules were taken to be identical. Lateral interactions were taken into account in the quasi-chemical approximation. The equilibrium distributions of the trace impurity across a pore section in the gas and liquid phases of the base component and at the interface for the case of capillary condensation were considered. The probability of existence of isolated dimeric clusters was estimated and the self-diffusion coefficients of the base component and trace impurity for a single-phase distribution of the base component were calculated. The effects of the energy of interaction of impurities with the pore walls and the concentration of the base component on the diffusion mobility of the impurities were analyzed. The concentration dependences of the partition coefficient for the trace impurity between the pore center and the pore wall and the concentration dependences of the self-diffusion coefficients for the trace impurity molecules become nonmonotonic with an increase in the base component concentration. These effects are due to the displacement of the impurity from the near-surface area to the bulk of a pore following an increase in the pore coverage by the base component and to higher mobility of the impurity in the free bulk of the pore. Further filling of the pore bulk reduces the mobility of all molecules. The energetics of intermolecular interactions also plays a certain role. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 605–615, April, 2000.     

Epimerization and racemization of some chiral drugs in the presence of human serum albumin

Epimerization and racemization of carbenicillin, ethiazide, etoposide and oxazepam acetate were examined kinetically in the presence of human serum albumin (HSA). The concentration of both optical isomers of each drug was determined by stereospecific high-performance liquid chromatography. The apparent rate constants of epimerization or racemization and hydrolysis were estimated from the concentration-time data. HSA retarded the racemization of ethiazide and the epimerization of etoposide. The binding of the drugs to HSA may inhibit the attack of hydroxy ion and/or water molecule and thus retard the epimerization and the racemization. HSA accelerated the epimerization of carbenicillin, which is charged at the pH studied. Ion-ion and ion-dipole interactions between carbenicillin and HSA activate the carbenicillin molecule favorable for the attack of hydroxy ion and/or water molecule. The hydrolysis rates of ethiazide, carbenicillin and oxazepam acetate were increased by the addition of HSA. The hydrolysis rate of d-oxazepam acetate enantiomer bound to HSA was twice that of the l-enantiomer, which suggests that the esterase-like activity of HSA is enantioselective. Differences in the binding affinities of the drug's enantiomers to HSA may account for the selectivity.     

Thermal Conversion of Heavy Oil Systems and Analysis of Structural Changes of their High Components with PMR Method

Heavy oil systems are thermolyzed with different ratios of amount of resins and asphaltenes: 3.4, 3.8, 5.3, and 12.4. The change in yield and composition of gaseous, liquid and solid products of thermolysis is shown depending on the ratio of the resin: asphaltenes. In the liquid products of thermolysis, resins content decreases and s the amount of asphaltenes and oils increases. According to PMR spectroscopy, the distribution of protons is compared in the secondary resin and asphaltene molecules of the initial samples and the thermolysis products. It is shown that the relative content of hydrogen aromatic rings in the molecules of asphaltenes is higher, and for β- and γ- positions relative to the aromatic rings and heterofunction, it is lower than in the resin molecules.     

以非标准答案试题推进人才培养模式改革——以大学化学课程为例

Classroom activity and effectivity is a common problem that high-level universities have not solved well for a long time. After ten years of teaching reform, Sichuan University has formed a prototype of the "Sichuan-University Mode" for talent training. Based on the macro perspective of the development and demands of the society, this essay reexamines the educational mission of the new age and analyzes the undergraduates and the inconsistency of their subjective and objective needs. Based on the results, the value of the academic achievement assessment reform of non-standard-answer exam to the talent cultivation is evaluated. We argued that the assessment reformation stems from the concept of non-standardization of education. It embodies the capacity and the tolerance of universities and teachers. It is an effective approach to nourish the students' mind and to optimize their thinking pattern. It is a combination of moral education, innovative education and professional education. It strongly supports the goal of first-class talent training and is easy to operate in class. Hopefully, non-standard-answer examination could become a teaching paradigm benefiting to the classroom.     

Changes in the heavy metal contents of soil from the Park Grass Experiment at Rothamsted Experimental Station

The classical Rothamsted Experiments allow to contribute to current research. The heavy metal content of soil and hay samples have been measured with ICP-AES from a control and a fertilized plot of the Park Grass Experiment. Today a difference of 1.2 can be observed in the pH levels of the control and fertilized plots; the pH level of the control plot has decreased about 1.0, that of the fertilized plot about 2.2 as a result of 150 years of acid deposition and fertilization. The changes in the pH levels has caused many changes in the heavy metal content of the top layer of the soil. Using different extraction methods (e.g., ammonium acetate, EDTA, and sequential analysis), the heavy metal content of different fractions have been estimated. In the control plot, the Zn, Cd and Pb content increased. In the fertilized plot, the Pb and Cd contents have also increased because of atmospheric deposition and small amounts of lead in the fertilizer. The available form of Cd and Pb increased in both the control and the fertilized plots.     

Electron correlation studies by means of local-scaling transformations and electron-pair density functions

Electron correlation is one long standing problem of computational electronic structure theory. Even more, with the advent of the density functional theory and, in particular, with its Kohn–Sham implementation, the separation of the non-dynamical and dynamical components of the electron correlation has became an unavoidable requirement towards construction of reliable exchange-correlation functionals. In this paper, we address the analysis of the separation of the non-dynamical and dynamical electron correlation effects from two complementary viewpoints, namely, analysis of the correlation energy components and the analysis of the electron-pair density. The former approach will make use of the local-scaling transformations and the latter will be based on the study of intracule and extracule densities.Work supported by grant 9/UPV-00203.215-13527/2001of the Office of Universities and Research of the The Goverment of the Basque Country and, by grant BQU2001-0208 of the Spanish Ministry of Education and Science.Partially supported by grant G-97000741 of CONICIT of Venezuela.     

High-resolution microwave spectroscopic and ab initio studies of propanoic acid and its hydrates

High-resolution microwave spectra of the propanoic acid monomer (PPA) and two of its hydrates, the PPA-(H2O) and the PPA-(H2O)2, were recorded using a pulsed nozzle Fourier transform microwave spectrometer. The rotational and centrifugal distortion constants of these species were determined. Agreements between the experimental and ab initio results of these constants, and of the planar moment of inertia, the dipole moments, and the orientation of the PPA relative to the H2O confirm the geometry of the hydrates, i.e. H2O binds to the carboxylic group of PPA and forms hydrogen-bonded ring complexes. The equilibrium constant and the change of entropy and enthalpy for the formation of PPA-(H2O) were also derived, based on the calculation of partition functions, to evaluate the abundance of this monohydrate in the troposphere.     

Statistical Theory of Stable and Meta-stable Transition for Crystallization and Fusion of Homopolymers Ⅵ. Statistical Dynamics of Polymeric Crystallization by Molecular Segregation-Dependence of Crystal Growth Rate on the Grown Mechanism and Concentratio

First a short review on the dependence of crystal growth rate on the growth mechanism and concentration is present. Based on the structural model of micronucleus and crystal constituent chains, and the feature of statistical dynamics for polymeric crystallization by molecular segregation, a general method for characterizing number the growth rate and micro crystal constituent chains and the size growth rate for crystals was proposed. According to this method, a set of quantitative expressions for correlating the growth rate in number and size with the four types of growth (folding, extending and combination of folding and extending), the crystalline temperature and the crystalline concentration was derived. Then combined the concentration index is combined with the fraction of conformation for segments, a new correlation of the concentration index to the temperature of crystallization and the flexibility of polymeric chain is theoretically obtained. The dependences of the index on the different types of growth are also studied. Finally the relationships between the growth rate for crystals and the concentration of solution were verified by the experimental validating the predictions made by the theory.