Radiochemistry teaching and research activities in Brazil

Summary Much concern has been expressed lately about the decline of teaching and research activities in radiochemistry in many countries, as was discussed in an IAEA Technical Meeting in Antalya, Turkey, in 2002, and also at MTAA-11 in Guildford, UK. In the IAEA meeting, a survey was presented about the current situation in different regions of the world (Eastern Europe, East and West Asia, Africa, North America and Latin America) by experts of each region. In the case of Brazil, which has nuclear research reactors and also cyclotrons in operation, the teaching and research activities in radiochemistry are concentrated in the three main institutes of the Brazilian Nuclear Energy Commission, in the University of S?o Paulo and in other universities, in different regions of the country. In the present paper, a closer look is given to the radiochemistry teaching and research activities that are being conducted nowadays in Brazil, comprising: number of radiochemistry courses and students being formed, main research areas being conducted, as well as research and production of radioisotopes for nuclear medicine, using nuclear reactors and cyclotrons.     

黄鸣龙——我国有机化学的一位先驱

黄鸣龙院士(1898-1979)1919年浙江医药专科学校毕业,1924年德国柏林大学有机药物化学博士;1924-1934年任浙江医专教授、主任,卫生署化学部主任;1934-1940年在欧洲先灵公司等从事研究工作;1940年回国在昆明任中研院化学所研究员,兼任西南联大教授;1945年赴美在哈佛大学,默克公司从事研究工作。1952年绕道欧洲回国,先后在中国人民解放军医学科学院化学系和中国科学院上海有机化学研究所任研究员。1955年当选为中国科学院学部委员(院士)。黄先生一生从事有机化学的教育和研究工作,他在有机化学的“结构与机理”以及“反应和合成”二大方面都作出了在国内外具有深远影响的工作。20世纪40年代黄先生发现了变质山道年4个立体异构体的循环转变,堪称立体化学的经典之作;1948年发表了黄鸣龙还原反应;1952年归国后引领和发展了我国的甾体化学研究,带领了我国甾体药物的生产发展,是我国甾体药物工业的奠基人。黄先生治学严谨,既重视应用研究,又强调基础研究;关注学习新知识、新概念,又更重视实验技术。黄先生教书育人,身体力行,是我国有机化学发展的先驱者和奠基人。     

Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

Dendrimers with electroactive units in the core or in each branching centre

Interest in dendrimers is mostly focused on their capability of performing specific functions which, in their turn, derive from the possibility of incorporating in predetermined sites of the structure selected functional groups (‘pieces of information’). From a topological viewpoint we can distinguish dendrimers containing electroactive units (a) in the core, (b) in the branches, (c) in the surface, (d) in the core and in the branches, (e) in the core and in the surface, (f) in the branches and in the surface, and (g) in the core, branches and surface. In this article we review the behaviour of dendrimers with electroactive units buried in the core and dendrimers with electroactive units in each branching centre investigated in our laboratory. To cite this article: M. Venturi, P. Ceroni, C. R. Chimie 6 (2003).     

Research progress of graphene-based nanomaterials for the environmental remediation

Graphene is a two-dimensional nanomaterial with huge surface area,high carrier mobility and high mechanical strength.Because of its great potential in nanotechnology and environmental protection,it has attracted much attention in environmental and energy fields since its discovery in 2004.Although graphene is a star material,many reviews have introduced its use in terms of energy,the research progress in the field of environment,especially water pollution control,has been rarely reported.Here,we review exhaustively the research progress of graphene-based materials in environmental pollution remediation in the past ten years.Firstly,the advantages and classification of graphene were introduced.Secondly,the research progress and main achievements of graphene and its composites in the fields of photocatalytic degradation,pollutant adsorption and water treatment were emphatically described,and the mechanism of action in the above fields was summarized.Finally,we discuss the problems existing in the preparation and summarize the application of graphene in the environment.     

Simultaneous liquid chromatographic determination of 39 polycyclic aromatic hydrocarbons in indoor and outdoor air and application to a survey on indoor air pollution in Fuji, Japan

An analytical method was established for the simultaneous determination of 39 polycyclic aromatic hydrocarbons (PAHs) in air. The method was applied to a survey of gaseous and particulate PAHs in household indoor air. The survey was performed in 21 houses in the summer of 1999 and in 20 houses in the winter of 1999-2000 in Fuji, Japan. Thirty-eight PAHs were determined in indoor and outdoor air in the summer, and 39 PAHs were determined in indoor and outdoor air in the winter. The concentrations of gaseous PAHs in indoor air tended to be higher than those in outdoor air in the summer and winter. The concentrations of particulate PAHs in indoor air were the same as or lower than those in outdoor air in the summer and winter. PAH profiles, correlations between PAH concentrations, and multiple regression analysis were used to determine the factors affecting the indoor PAH concentrations. These results showed that gaseous PAHs in indoor air were primarily from indoor emission sources, especially during the summer, and that indoor particulate PAH concentrations were significantly influenced by outdoor air pollution.     

Investigation of the activity and stability of papain in different micellar systems

Hydrolysis of PyrPheAlaPNa, catalyzed by papain in reverse micelles of ionogenic surfactant of Aerosol OT, and in octane, was studied in the presence and in the absence of nonionogenic surfactants of a different nature. As found, the dependence of the catalytic activity of papain on the hydration degree of the surfactant in reverse micelles of AOT has two maxima, corresponding to the activity of monomeric and oligomeric forms of the enzyme. It was established that the addition of nonionogenic surfactant of a different nature to the Aerosol OT in octane leads to changes of the catalytic properties of the enzyme, in particular, to its activation in the presence of Pluronic L61. Nanoemulsions of nontoxic nonionogenic surfactant and organic solvents, lecithin and Tween 20 in eucalyptus oil were created and characterized; with the use of the photon-correlation spectroscopy technique it was shown that the size of such particles lie in the range from 34 to 266 nm, depending on the water content, nature, and the concentration of system components, and factors regarding its shape lie in the interval 20–30, suggesting the presence of particles with a rod-like shape. It is important to note that in such systems, suitable for use in medicine and cosmetology, the activity of papain was revealed.     

Interactions and reactions of monolayers and Langmuir-Blodgett multilayers with compounds in the bulk phase

Studies performed on the interactions and reactions of compounds in the bidimensional state, essentially in monolayers and Langmuir-Blodgett multilayers, with substances in the aqueous subphase are reported. More precisely, the following is illustrated: (i) interactions between acid amphiphiles and prevalently bivalent ions placed in the aqueous support and between compounds capable of functioning like ion carriers in monolayers and ions in the subphase, in order to build mimetic membranes capable of selective ion transport; and the complexation of amphiphiles in monolayer with ions in the bulk liquid phase, in order to build chemical sensors to ions; (ii) the reactions of photoinduced electron transfer between a partner in mono- or multimolecular films and a partner in the subphase, which may determine the fundamental parameters and the differences with the same reactions in the bulk phase; and (iii) the reactions of enzymatic hydrolysis between the monolayer of a glyceride, which constitutes the reaction support, and the enzyme in the liquid bulk phase, which constitutes the subphase. The mechanism of the reactions and its inhibition are clarified. To conclude, possible future developments connected with the areas studied are examined.     

煤烘玉米和饮水为介质地氟病区骨畸形病人全血尿多元素含量的分析

采集了贵族个煤烘玉米为主要介质和河北２个饮水为介质氟病区内骨畸形病人的全血、尿、检测了其中８种元素含量,结果表明,贵州各氟病区少儿骨软化与成年骨硬化畸形病人的全血铝、钙、磷、铁和尿氟、铝均显著高于同龄对照组,尿磷均低于同龄对照组。少儿骨软化病人全血锌均下降,尿锌多下降。某水型氟病区骨软化经产妇尿氟、全血铜升高;骨软化少年全血铝显著升高,锌、铁下降,尿氟升高,尿锌,磷下降。海边的典型氟骨症病人全血、     

Histological study of some Echium vulgare, Pulmonaria officinalis and Symphytum officinale populations

Plants living in different ecological habitats can show significant variability in their histological and phytochemical characters. The main histological features of various populations of three medicinal plants from the Boraginaceae family were studied. Stems, petioles and leaves were investigated by light microscopy in vertical and transverse sections. The outline of the epidermal cells, as well as the shape and cell number of trichomes was studied in leaf surface casts. Differences were measured among the populations of Echium vulgare in the width and height of epidermis cells in the stem, petiole and leaf, as well as in the size of palisade cells in the leaves. Among the populations of Pulmonaria officinalis significant differences were found in the length of trichomes and in the slightly or strongly wavy outline of epidermal radial cell walls. Populations of Symphytum officinale showed variance in the height of epidermal cells in leaves and stems, length of palisade cells and number of intercellular spaces in leaves, and the size of the central cavity in the stem. Boraginaceae bristles were found to be longer in plants in windy/shady habitats as opposed to sunny habitats, both in the leaves and stems ofP. officinalis and S. officinale, which might be connected to varying levels of exposure to wind. Longer epidermal cells were detected in the leaves and stems of both E. vulgare and S. officinale plants living in shady habitats, compared with shorter cells in sunny habitats. Leaf mesophyll cells were shorter in shady habitats as opposed to longer cells in sunny habitats, both in E. vulgare and S. officinale. This combination of histological characters may contribute to the plant's adaptation to various amounts of sunshine. The reported data prove the polymorphism of the studied taxa, as well as their ability to adapt to various ecological circumstances.     

Separation characteristics of air by polysulfone hollow fiber membranes in series

Characteristics of air separation are determined in a serial configuration of hollow fiber polysulfone membranes. One, two, and three separation cells in series are used in the measurements. All systems are operated in the counter-current flow mode and effects of the reject flow rate and feed pressure are considered in the measurements. The plug flow model is used to simulate and analyze the system. Results include variations in species permeance, stage cut, permeate enrichment, reject depletion, and recovery of oxygen and nitrogen gases. Most of the plug flow model predictions are found to closely match the measured data, with deviations less than 10%. However, deviations in N₂ recoveries are found to be larger than other system parameters, with deviations close to 30%. Increase of the number of separation cells results in higher stage cuts and in turn to higher species recovery in the permeate stream. Simultaneously, the purity of the reject is increased and that of the permeate stream is decreased. At constant reject flow rate, the highest permeate enrichment is found in the permeate stream of the first cell in the two- and three-cell systems. This is caused by the increase in the feed flow rate, which results in reduction of the gas residence time and in turn the gas permeation is highly selective and is dominated by the fast permeating species O₂.     

Determination of Occurrence Characteristics of Heavy Metals in Soil and Water Environments in Tianshan Mountains,Central Asia

China has one of the fastest-growing economies in the world, but this economic development has important implications for environmental changes in this country. Our research was to quantify the presence of heavy metals in soil and water environments in the Tianshan Mountains region of China, associated with the economic development of this region. We used anomaly analysis, correlation analysis, and principal component analysis to assess the occurrence characteristics of heavy metals in this area. Results showed that Co, Cr, As, and Ni are more prevalent in water environments than in soil environments; in contrast, Cd, Zn, Pb, Hg, and Mn are more prevalent in soil samples than in water samples. This analysis grouped 10 heavy metals in soil and water environments into three principal components. In soil environments, the prevalence order was Co, Ni, Cr, As > Mn, Zn, Pb > Hg, Cd, Cu. In water environments, the order was Cu, Co, Ni, Cr, As > Hg, Mn, Zn > Cd, Pb. It is possible to distinguish between the natural and the anthropogenic sources of heavy metals in the Tianshan Mountains. With the current rapid economic development in the Tianshan Mountains, anthropogenic sources are playing principal roles in serious heavy metal accumulations in this region. This problem warrants immediate and widespread attention to prevent further deterioration of the soil and water environments.     

Amount of sterols and triterpenoids in leaves and petioles of leaf-shedding and standard lines of cotton plant

The amount of free and bound sterols and triterpenoids in the leaf blades and petioles of the variety Tashkent-1 and the deciduous lines L-275 and L-470 in the budding-flowering, maturing, and leaf-fall phases have been compared. In the leaf blades, the maximum accumulation of free sterols in the deciduous lines is observed in an earlier phase than in the variety Tashkent-1, and this is most characteristic for sterols saturated in the C-17 side chain. The dynamics of the change in the content of unsaturated sterols is individual for each line. The nature of the change in the amount of free sterols in the petioles is typical for each line and does not depend on the nature of the sterol for the variety Tashkent-1 this index falls sharply in the leaf-fall phase while for L-275 the process is retarded between the second and third phases, and for L-470 in the same period the amount of these substances rises sharply. In the leaf blades, as a rule, the level of sterol esters changes in parallel with the levels of free sterols, and in the petioles in the antiparallel direction between the first and second phases. In all the samples free and bound amyrin was detected. The dynamics of the change in the amounts of these substances in the three lines were different.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Institute of Experimental Plant Biology, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, pp. 796–805, November–December, 1989.     

Amount of sterols and triterpenoids in leaves and petioles of leaf-shedding and standard lines of cotton plant

The amount of free and bound sterols and triterpenoids in the leaf blades and petioles of the variety Tashkent-1 and the deciduous lines L-275 and L-470 in the budding-flowering, maturing, and leaf-fall phases have been compared. In the leaf blades, the maximum accumulation of free sterols in the deciduous lines is observed in an earlier phase than in the variety Tashkent-1, and this is most characteristic for sterols saturated in the C-17 side chain. The dynamics of the change in the content of unsaturated sterols is individual for each line. The nature of the change in the amount of free sterols in the petioles is typical for each line and does not depend on the nature of the sterol for the variety Tashkent-1 this index falls sharply in the leaf-fall phase while for L-275 the process is retarded between the second and third phases, and for L-470 in the same period the amount of these substances rises sharply. In the leaf blades, as a rule, the level of sterol esters changes in parallel with the levels of free sterols, and in the petioles in the antiparallel direction between the first and second phases. In all the samples free and bound amyrin was detected. The dynamics of the change in the amounts of these substances in the three lines were different. Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Institute of Experimental Plant Biology, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, pp. 796–805, November–December, 1989.     

大气臭氧化学研究进展

臭氧是大气化学中的核心物种。在平流层中,臭氧层可以吸收对生物有害的紫外辐射,对地球生命起保护伞作用。在对流层大气中,适量臭氧对清洁大气是有益的。但是,由于对流层中臭氧前体物排放量的增加,特别是在大城市,产生的高浓度臭氧会对大气环境造成严重污染,对人类、动植物和生态环境具有极大危害。臭氧的研究一般结合外场观测、实验室烟雾箱模拟和计算机数值模拟进行。深入开展大气臭氧化学研究,不仅有助于全面深入理解大气氧化过程以及全面掌握区域乃至全球大气自净能力,而且能为对流层污染控制提供科学依据和方案。本文总结了近年来有关臭氧化学的研究进展,论述了臭氧问题与人类当前面临的一些主要环境问题间的相互关系;重点综述了近年来有关南极臭氧空洞、中纬度地区臭氧低值和北极地区臭氧的损耗机理及其发展趋势;综述了臭氧与大气光化学和气溶胶间的耦合关系,并结合我国实际情况,提出了大气臭氧化学尚待深入开展研究的一些重要科学问题。     

中性溶质在反相毛细管电色谱中的保留行为

分别在以甲醇、乙腈、异丙醇和四氢呋喃为有机改性剂的４种二元流动相体系中对中性溶质在反相毛细管电色谱中的保留行为进行了研究。不仅考察了有机改性剂的种类和浓度对电渗淌度的影响,而且建立了溶质容量因子与有机改性剂在流动相中体积分数间的定量关系,此外还对样品在反相毛细管电色谱和反相毛细管高效液相色谱中的保留行为进行了比较,发现中性溶质在这两种分离模式中的容量因子基本相同。     

Membrane lipids are both the substrates and a mechanistically responsive environment of TMEM16 scramblase proteins

Recent discoveries about functional mechanisms of proteins in the TMEM16 family of phospholipid scramblases have illuminated the dual role of the membrane as both the substrate and a mechanistically responsive environment in the wide range of physiological processes and genetic disorders in which they are implicated. This is highlighted in the review of recent findings from our collaborative investigations of molecular mechanisms of TMEM16 scramblases that emerged from iterative functional, structural, and computational experimentation. In the context of this review, we present new MD simulations and trajectory analyses motivated by the fact that new structural information about the TMEM16 scramblases is emerging from cryo-EM determinations in lipid nanodiscs. Because the functional environment of these proteins in in vivo and in in vitro is closer to flat membranes, we studied comparatively the responses of the membrane to the TMEM16 proteins in flat membranes and nanodiscs. We find that bilayer shapes in the nanodiscs are very different from those observed in the flat membrane systems, but the function-related slanting of the membrane observed at the nhTMEM16 boundary with the protein is similar in the nanodiscs and in the flat bilayers. This changes, however, in the bilayer composed of longer-tail lipids, which is thicker near the phospholipid translocation pathway, which may reflect an enhanced tendency of the long tails to penetrate the pathway and create, as shown previously, a nonconductive environment. These findings support the correspondence between the mechanistic involvement of the lipid environment in the flat membranes, and the nanodiscs. © 2019 Wiley Periodicals, Inc.     

DFT calculations of the ionization potentials and electron affinities of serinamide

Adiabatic and vertical ionization potentials (IPs) and valence electron affinities (EAs) of serinamide in the gas phase have been determined using density functional theory (DFT) B3LYP, B3P86, and B3PW91 methods with the 6‐311++G** and 6‐311G** basis sets, respectively. IPs and EAs of serinamide in solution have been calculated with the B3LYP method using the 6‐311++G** and 6‐311G** basis sets. Eight possible conformers of serinamide and its charged states in the gas phase have been optimized employing the DFT B3LYP method with 6‐311++G** and 6‐311G** basis sets, respectively. All the adiabatic and vertical ionization potentials (AIPs and VIPs) of eight serinamide conformers in our work are positive values, whether in the gas phase or in solutions; the IPs in solutions are smaller than the results in the gas phase and decrease with increased dielectric constants in solutions. This finding indicates that the cationic states in solutions are more stable than those in the gas phase. All EAs of eight serinamide conformers are negative values in the gas phase, indicating that the anionic states are unstable with respect to electron autodetachment, both adiabatically and vertically. In contrast, all other adiabatic electron affinities (AEAs) are negative values in solutions except for 6S in water; 7S in chloroform, acetone, and water; and 8S in acetone and water, and increase with increasing of dielectric constants in solutions. All vertical electron affinities (VEAs) are negative values in solutions; however, no good rule has been found for these values in solutions. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Tautomerism of pyrimidines and purines in the gas phase and in low-temperature matrices,and some biological implications

Infrared spectra in the NH, OH, and C?O stretching regions are reviewed for various methylated and halogenated 2(4)-oxopyrimidines and uracils, as well as other nucleic acid derivatives, in the vapor phase and in low-temperature matrices. The 2-oxopyrimidines are predominantly in the enol form both in the vapor phase and in low-temperature matrices. By contrast, the 4-oxopyrimidines exhibit comparable populations of the keto and enol forms, with K_T ≈ 1–2, and a difference in chemical binding energy between the two forms in the gaseous phase of the order of 1–2 kcal/mol. The observed tautomeric equilibria in the gas phase point to the need for a drastic revision of interpretations of theoretical methods, and simultaneously provide the appropriate quantitative data necessary for testing the results of quantum mechanical calculations. In sharp contrast to other heterocyclic systems, several of the bases found in natural nucleic acids were found to exist predominantly in the keto or amino forms, as in the solution phase. In particular, uracils exist predominantly in the keto form. This has made possible, for this class of compounds, to evaluate the heats of sublimation and vaporization, and to relate these data to hydrogen bonding and stacking interactions in the condensed phases. Examples are presented of base analogs which do exhibit appreciable tautomerism in solution. Some biological implications of the foregoing are presented in relation to the types of heterocyclic bases found in natural nucleic acids, and to concepts of spontaneous and induced mutagenesis.     

A study of the postnatal change in trace element levels in rat tissues by thermal neutron activation analysis

In order to obtain information about postnatal changes in trace element levels in rat tissues, the age-dependent variations in the concentrations of 6 elements (Fe, Zn, Co, Se, Rb and Cs) were investigated by thermal neutron activation analysis. Several variation patterns were revealed in their concentrations as a function of postnatal age, depending on the combination of an element and an organ: (1) A steady state without significant variations (Zn and Se in brain, Rb and Cs in liver), (2) accumulation till a steady level is attained in time (Se in liver and kidney, Co in kidney), (3) depletion till a steady level is attained in time (Fe and Co in brain, Zn in liver and kidney, Rb and Cs in kidney), (4) permanent depletion (Rb and Cs in brain), and 95) initial drop followed by gradual increase in concentration levels (Fe in liver and kidney, Co in liver)