Recent developments in radioanaytical technologies for environmental investigations

Radiometric techniques, specifically underground gamma-ray spectrometry, have been recently widely applied in the analysis of short and medium-lived radionuclides in the environment. Long-lived radionuclides have been mostly analysed by Accelerator Mass Spectrometry and Inductively Coupled Plasma Mass Spectrometry. These developments have considerably improved the detection limits for analysis of radionuclides in the terrestrial and marine environments. They have also decreased required sample volumes so applications, which have not been possible before either because of sample size or required sensitivity, have become feasible. The recent developments are illustrated by applications of radiometric and mass spectrometry techniques in isotope hydrology and oceanography.     

Physicochemical Studies on Biological Macro- and Microemulsions VI : Mixing Behaviors of Eucalyptus Oil,Water and Polyoxyethylene Sorbitan Monolaurate (Tween 20) Assisted by n-Butanol or Cinnamic Alcohol

The phase behavior of Eucalyptus oil/ Tween 20/ Butanol/ Water and Eucalyptus oil/ Tween 20/ Cinnamic Alcohol/ Water systems have ben studied in detail. Both triangular and tetrahedral representations have been considered to understand the topological nature of the multicomponent mixtures. Shear viscosities of typical multiphasic compositions have been measured at different rates and temperatures. The samples have undergone shear thinning. The effect of temperature on the volumes of multiphasic compositions have been also investigated both increase and decrease of the extents of different phases have been witnessed. The enthalpy of dissolution of both water and oil in presence of amphiphile solutions in oil and water respectively have been determined calorimetrically. Considering the phase separation point to be the point of maximum solubility of microdroplets, the free energies and hence entropies ofsolution have been estimated. The above phy.sicochemical features have been also examined in presence of additives, viz, NaGI and urea.     

CRETACEOUS MAGNETOSTRATIGRAPHY IN THE SONGLIAO BASIN, CHINA

This paper is the result of research on the Cretaceous magnetostratigraphy in the Songliao Basin. The palaeomagnetic experiment on 2235 specimens from 24 drills and an outcrop profile in Quantou shows that most specimens have stable remanent magnetization.The features of polarities associated with all the rock formations of the Cretaceous in the Songliao plain have been summarized. The reversed polarity zones have been found in the Yingcheng, Dcnglouku, Yaojia and Nenjiang Formations. These reserved-polarity zones and their geologic ages have been argued. Accordingly. the polarity columns for different drills and a comprehensive column have been compiled, and the classification and correlation of the Cretaceous stratigraphy in the Songliao Basin have been discussed.     

Mass spectra of some oxadiazole derivatives

The mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4-oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4- and 1,2,4-oxadiazoles, and possible mechanisms are proposed.     

Structure and reactions of reduction products in crystalline and polymeric materials by combining pulse radiolysis and ESR

The structure and the reactions of primary oxidation and reduction products in irradiated organic crystals and solid polymers have been investigated. The data from pulse radiolysis with nanosecond time resolution have been combined in a new manner with the data obtained by low-temperature irradiation and ESR spectroscopy. By this combination optical spectra have been assigned, reaction mechanisms have been studied and ESR components have been identified using the kinetic data from pulse radiolysis. The method has been particularly useful in the study of negative-ion radicals in carboxylic acid derivatives, of trapped electrons in polyhydroxy compounds, and of ionic species in polymers.     

Development and in situ synthesis of monolithic stationary phases for electrochromatographic separations

Organic monolithic stationary phases have been synthesized in UV-transparent fused-silica capillaries, which have been used as test format of microfabricated device channels. The columns have been prepared by in situ polymerization of butyl acrylate, lauryl acrylate, 1,3-butanediol diacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in a ternary porogenic solvent. The resulting stationary phases have been tested in capillary electrochromatography and exhibited reversed-phase chromatography behavior toward neutral solutes. Van Deemter plots of phenylureas and polycyclic aromatic hydrocarbons, selected as model analytes, have been determined to study the influence of various polymerization and separation parameters on properties of the monoliths. The amount of AMPS and the nature of monomers in the polymerization solution have been thus adjusted. It has been observed that the ionic strength of the mobile phase may affect significantly the efficiency of the separation. The effect of the percentage of acetonitrile in the mobile phase on efficiency and permeability of the organic monoliths has also been investigated. Efficiencies greater than 300,000 plates/m have been obtained with the test compounds. Stability and reproducibility have been extensively studied.     

Short peptides as biosensor transducers

This review deals with short peptides (up to 50 amino acids) as biomimetic active recognition elements in sensing systems. Peptide-based sensors have been developed in recent years according to different strategies. Synthetic peptides have been designed on the basis of known interactions between single or a few amino acids and targets, with attention being paid to the presence of peptide motifs known to allow intermolecular self-organization of the sensing peptides over the sensor surface. Sensitive and sophisticated sensors have been obtained in this way, but the use of designed peptides is limited by severe difficulties in their in silico design. Short peptides from random phage display have been selected in a random way from large, unfocussed, and often preexisting and commercially available phage display libraries, with no design elements. Such peptides often perform better than antibodies, but they are difficult to select when the target is a small molecule because of the need to immobilize it with considerable modifications of its structure. Artificial, miniaturized receptors have been obtained from the reduction of the known sequence of a natural receptor down to a synthesizable and yet stable one. Alternatively, binding sites have been created over a designed, stable peptide scaffold. Short peptides have also been used as active elements for the detection of their own natural receptors: pathogenic bacteria have been detected with antimicrobial and cell-penetrating peptides, but key challenges such as detection of bacteria in real samples, improved sensitivity, and improved selectivity have to be faced. Peptide substrates have been conjugated to fluorescent quantum dots to obtain disposable sensors for protease activity with high sensitivity. Ferrocene–peptide conjugates have been used for electrochemical sensing of protease activity.     

Synthese de substances macromoleculaires renfermant des motifs monomeres derives de colorants—XIX: Synthese d'oligoethers et d'oligoesters colores par structure

Oligo-oxyethylenes and oligo(oxyethylenes-Co-oxypropylenes) with hydroxy end-groups have been modified by nitration and amination of the end-groups; the modification was partial in some cases and complete in others. Amino end-groups have been diazotized and the oligomers with azo end-groups have been coupled with β oxynaphthic acid and N,N′diethylaniline. Oligomers with chromophoric and hydroxy groups in the chain have been used to prepare polyurethane foams. Structurally coloured polyesters have been synthesized similarly and used to prepare polyurethane elastomers. All these oligomers have been characterized by i.r. and visible spectroscopy, NMR, end-group titration, vapour pressure osmometry and thermal differential analysis.     

Phase structure of silanol-modified ethylene-vinyl acetate copolymers

For (ethylene-vinyl acetate copolymer)-tetraethoxysilane and (ethylene-vinyl acetate copolymer)-polydimethylsiloxane systems, the solubility of components has been studied in a wide range of temperatures and compositions. Phase diagrams have been constructed, pair interaction parameters have been calculated, and diffusion coefficients and activation energies of diffusion have been estimated. The temperature and concentration ranges of a change in solubility related to chemical interactions between the components have been revealed, and the structure of the modified copolymers has been studied. On the basis of the kinetic data on the movement of isoconcentration planes in diffusion zones of component mixing, time intervals corresponding to the onset of the chemical reaction between the components have been determined and the apparent activation energies of the process have been computed. Complex-shaped binodal and boundary curves have been interpreted within the framework of the classical Flory-Huggins theory.     

生物质谱--蛋白质组研究的关键技术

介绍了近几年来国际上重点研究的几类新型生物质谱技术,综述了它们在蛋白质组研究中的最新进展,比较了各自的特点,简要评价了它们在蛋白质组研究中的应用和前景。     

Mushroom Polysaccharide-Assisted Anticarcinogenic Mycotherapy: Reviewing Its Clinical Trials

Of the biologically active components, polysaccharides play a crucial role of high medical and pharmaceutical significance. Mushrooms have existed for a long time, dating back to the time of the Ancient Egypt and continue to be well explored globally and experimented with in research as well as in national and international cuisines. Mushroom polysaccharides have slowly become valuable sources of nutraceuticals which have been able to treat various diseases and disorders in humans. The application of mushroom polysaccharides for anticancer mycotherapy is what is being reviewed herein. The widespread health benefits of mushroom polysaccharides have been highlighted and the significant inputs of mushroom-based polysaccharides in anticancer clinical trials have been presented. The challenges and limitation of mushroom polysaccharides into this application and the gaps in the current application areas that could be the future direction have been discussed.     

γ-取代丙基环四硅氧烷的合成及其与D_4的乳液共聚反应

本文合成了四种γ-取代丙基环四硅氧烷。通过阳离子型和阴离子型乳液共聚的方法,分别使其与八甲基环四硅氧烷共聚,合成了含有γ-羟丙基、γ-氯丙基和γ-乙酰氧丙基等活性碳官能团有机硅聚合物的稳定乳液;研究了乳液共聚反应过程中的单体转化率、聚合物分子量的变化以及温度、催化剂、乳化剂、取代基团等因素的影响。     

Nucleation-controlled multiphase transitions

Thermodynamics and kinetics of phase transitions in multiphase systems have been discussed. Thermodynamically admissible transitions have been identified and transition kinetics described in terms of the extended Kolmogoroff-Avrami-Evans model. Different combinations of transitions have been described as directed graphs. Graph nodes represented individual phases, graph edges--transitions. Superposition of parallel transitions in various mother phases, simultaneous transition of the same mother phase into different target phases, and successive (chain) transitions have been analyzed. Detailed solutions for a three-phase system consisting of one liquid phase and two polymorphic solid phases have been presented.     

新型汽车发动机油用添加剂的研究进展

本文介绍了汽车发动机油用添加剂尤其是多功能添加剂的发展概况、作用机理、种类、结构及应用效果，并对未来润滑油添加剂的发展方向提供了一些参考，为我国润滑油品的高档化发展提出了几点想法。     

水分散性硫化镉纳米粒子的制备研究进展

表面修饰的硫化镉纳米粒子荧光性能优异而稳定,激发光谱宽,发射光谱窄而对称且发射波长可通过改变材料的粒径大小和组成来调控,因而在生物样本尤其是活组织的多色成像中极为有用,能有效避免因样本自身发光和光散射导致的信号干扰。硫化镉纳米粒子的研究已被许多科研工作者所青睐,是目前热点研究领域之一。近年来,水分散性硫化镉纳米粒子作生物荧光标记物的研究取得了长足的进展。本文综述了水分散性硫化镉纳米粒子的制备方法研究进展,分析了各种制备方法的优点与不足之处。     

Synthesis,structure, and spectral fluorescence properties of 1,4-di(5-phenyl-2-oxazolyl)benzene heteroanalogs

Novel organic luminophors belonging to the oxazole and oxadiazole classes of compounds have been synthesized, namely, thiophene and furan analogs of 1,4-di(5-phenyl-2-oxazolyl)benzene. The optical properties of these compunds have been studied both theoretically and experimentally. Their IR spectra have been measured and their UV absorption, fluorescence, and excitation spectra have been analyzed. Details of their electronic structure and their principal spectral fluorescence parameters have been calculated using the PPP method. Possible methods or pathways for improving the spectral fluorescence parameters of organic luminophors in these classes of compounds in the visible region of the spectrum have also been analyzed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1414–1419, October, 1989.     

The study of atropoisomers of meso-tetrakis[2.2]paracyclophanylporphyrin

Theoretical considerations of atropoisomers of the title compound have revealed the existence of a large number of stable isomeric species. Syntheses, carried out according to two procedures at widely separated temperatures, resulted in the formation of mixtures of atropoisomers in good yield. Two isomeric fractions have been separated and characterized. Some analytical methods have been worked out and have proved useful in separational techniques.     

Scalp hair as a monitor of population exposure to environmental pollutants

Concentrations of As, Cd, Hg, Pb, Sb and Zn have been measured in hair from population groups with varied types of environmental exposure. Rural and urban controls have exhibited low levels of most toxic elements, whereas people residing near urban lead refineries, rural gold refinery and other industries have shown high elemental concentrations in their hair. A combination of instrumental as well as radiochemical neutron and photon activation analysis methods have been used to determine the concentrations of the above elements. The precision and accuracy of these methods have been evaluated.     

Bulk radical homo-polymerisation studies of commercial acrylate monomers using near infrared Fourier transform Raman spectroscopy

In our previous work we have used near infrared Fourier transform Raman spectroscopy to provide a reliable, reproducible and quantitative method for in situ reaction monitoring of homo-polymerisation. Model systems such as styrene and methylmethacrylate were studied. In this present work three commercial monomers have been studied, namely butylacrylate, hydroxylpropylmethacrylate and laurylmethacrylate. The effects of reaction temperature, monomer additives and the presence of oxygen have been elucidated. These reaction variables have been shown to have a significant effect on polymerisation rate in particular for the butylacrylate system.     

3 006例妇女乳腺病情况分析

为通过普查,使妇女乳腺病早发现,早治疗,2004年6月至2006年5月,对惠州市区机关,企业单位和常住人口的妇女3 006例进行了乳腺普查,主要方式有望诊,触诊,B超,红外线乳腺检查仪,病理检查等手段。结果表明,患乳腺疾病人数为1 352例,患病率为44.82%,其中乳腺小叶增生1 140例,乳腺纤维瘤81例,乳腺多发性囊肿89例,溢乳症27例,乳腺炎10例,乳腺癌5例。乳腺增生症、多发性囊肿、纤维瘤患病率为30~49岁年龄组较高。乳腺癌患病率为30岁以上年龄组较高,5例乳腺癌患者均为此年龄段,经对照分析有显著的差异。建议:加大妇女乳腺疾病普查普治工作力度,坚持乳腺疾病宣传,加强广大妇女自我保健意识,达到降低乳腺疾病发病率,提高乳腺癌的早期诊断率。