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.     

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.     

Facile synthesis methodology and characterization studies of silica-decorated hybridized anisotropic nanotubes and nanosheets

Carbonaceous nanomaterials and their derivatives have been inspired tremendous enthusiasm in the scientific community. They have been excogitated as the encouraging attributes and the qualified dispersed phase to develop multi-functional composites. Particularly, graphene and carbon nanotube (anisotropic fillers) have gained substantial research interest owing to their promising characteristics. This highlights an innovative technique to synthesize hybridized nanotube and nanosheet. Initially, parent materials have been synthesized: The pristine CNT has been modified by acid mixture solution, and reduced graphene oxide has been prepared by chemical reduction method. Henceforth, the self-assembly in situ sol–gel technique has been endorsed here. The synthesized nanohybrids have been characterized by different spectroscopic techniques: FTIR, Raman, UV, and XPS to confirm the attachment of multifunctionalities; meanwhile, the composition and stability have been investigated from XRD and TGA plots. The magnitude of surface charge and particle size distribution have been evaluated for the parent and hybridized products; further, morphology of all the samples has been authenticated from FESEM and TEM.     

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.     

侧链液晶高分子的非线性光学特征及其应用

阐述了侧链高分子液晶非线性光学的基本原理,着重讨论了影响非线性光学特征的几个基本因素,说明了双折射与外场强度、双折射与序参数之间的定量关系,展望了侧链高分子液晶非线性光学特征在一些领域中的应用前景。     

Influence of low concentration silver nanoparticles on the electrical and electro-optical parameters of nematic liquid crystals

Thermodynamical, optical, dielectric and electro-optical characterisation of nematic liquid crystals (LCs) and silver nanoparticle (NP) composites have been carried out. Transition temperatures of pure and composites systems have been measured. Thermodynamical studies suggest increase of clearing temperature of the composite material as compared to the pure material. Threshold voltage for switching from bright to dark state and splay elastic constant of the pure and composite materials have been determined. From frequency dependence of dielectric measurements, permittivity, loss, relaxation frequency and dielectric strength of flip-flop mechanism of LC molecules in the nematic phase have been calculated. Dielectric properties of composites have been explained in reference of Maier and Meier theory. The effects of doping of NPs on dielectric and electro-optic properties of LC-NP composites have been discussed.     

Synthesis of monodisperse spherical nanocrystals

Much progress has been made over the past ten years on the synthesis of monodisperse spherical nanocrystals. Mechanistic studies have shown that monodisperse nanocrystals are produced when the burst of nucleation that enables separation of the nucleation and growth processes is combined with the subsequent diffusion-controlled growth process through which the crystal size is determined. Several chemical methods have been used to synthesize uniform nanocrystals of metals, metal oxides, and metal chalcogenides. Monodisperse nanocrystals of CdSe, Co, and other materials have been generated in surfactant solution by nucleation induced at high temperature, and subsequent aging and size selection. Monodisperse nanocrystals of many metals and metal oxides, including magnetic ferrites, have been synthesized directly by thermal decomposition of metal-surfactant complexes prepared from the metal precursors and surfactants. Nonhydrolytic sol-gel reactions have been used to synthesize various transition-metal-oxide nanocrystals. Monodisperse gold nanocrystals have been obtained from polydisperse samples by digestive-ripening processes. Uniform-sized nanocrystals of gold, silver, platinum, and palladium have been synthesized by polyol processes in which metal salts are reduced by alcohols in the presence of appropriate surfactants.     

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.     

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。     

Overpressured thin-layer chromatography

The properties, apparatus and applications of overpressured thin-layer chromatography (OPTLC) have been reviewed. In the Introduction planar chromatography has been briefly characterized, with particular attention to TLC. The general properties of OPTLC and methods of development of chromatograms in this technique have been then given. The construction of chambers and equipment for OPTLC has been described, paying attention to two-dimensional columns. The properties of chambers for OPTLC have been characterized considering the flow of eluent, sorbent-eluent interactions and the efficiency of various systems. OPTLC, TLC and HPTLC have been compared and also a comparison between OPTLC with a constant (linear) eluent flow-rate and with a decreasing eluent flow-rate has been made. Analytical applications of OPTLC have been described and examples of separations of mixtures have been given.     

Improved microbiological hydroxylation of sesquiterpenoids: semisynthesis,structural determination and biotransformation studies of cyclic sulfite eudesmane derivatives

Two new cyclic sulfite eudesmane derivatives have been investigated. Their (R) and (S) sulfur configuration and the structural arrangement of their "A" rings have been assigned by means of their 13C and 1H NMR chemical shifts and have been confirmed by single-crystal X-ray analyses. Microbial-transformation of these epimer cyclic sulfites and their dihydroxyeudesmane precursor have been studied using the hydroxylating fungus Rhizopus nigricans. Increased biocatalysis rates and considerable differences in the biotransformation of both cyclic sulfite eudesmanes have been found. Promising 8alpha,11-dihydroxy derivatives have been isolated from the (S)-diastereomer bioconversion.     

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.     

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.     

Curing of an epoxy resin modified with poly(methylmethacrylate) monitored by simultaneous dielectric/near infrared spectroscopies

Simultaneous dielectric and near infrared measurements have been performed in “real-time” to follow polymerisation reactions on blends of a diglycidyl ether of bisphenol-A epoxy resin with 4,4^′-diaminodiphenylmethane hardener and different amounts of poly(methylmethacrylate) as modifier. The effect of the modifier amount on the polymerisation reactions has been studied, as well as that of the curing temperature. Epoxy and amine conversions have been followed by near infrared spectroscopy (NIR), while changes in molecular mobility in the reaction mixture have been analysed by dielectric relaxation spectroscopy (DRS). Evolutions of ionic conductivity and α-relaxation have been analysed and vitrification times have been obtained. The relaxational behaviour has been analysed through curing in the frequency domain, being the change of the main relaxation indicative of the cure reaction advancement. DRS data are also presented as complex impedance Z(ω). Vitrification times, obtained by dielectrometry have been compared with those obtained by rheological measurements and gelation times obtained by NIR have been compared with those obtained by solvent extraction.     

Copper ferrocyanide — polyurethane foam as a composite ion exchanger for removal of radioactive cesium

A method has been developed for the removal of cesium from the aqueous radioactive waste using a composite ion-exchanger consisting of Copper-Ferrocyanide Powder (CFC) and Polyurethane (PU) Foam. Polyvinyl acetate has been used as a binder in the preparation of CFC-PU foam. The physical properties of CFC such as density, surface area, IR stretching frequency and lattice parameters have been evaluated and also its potassium and copper(II) content have been estimated. Optimization of loading of CFC on PU foam has been studied. The CFC-PU was viewed under microscope to find out the homogeneity of distribution. Exchange capacities of the CFC-PU foam in different media have been determined and column studies have been carried out. Studies have been undertaken on extraction of cesium from CFC foam and also on digestion of spent CFC-PU foam and immobilization of digested solution in cement matrix. The cement matrices have been characterized with respect to density, bio-resistance and leaching resistance.     

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.     

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.     

硫酸锌与L-亮氨酸配合物行为的研究

锌是生命元素,缺锌引起的各种疾病已引起全世界的共同注意.L-α-氨基酸是人体蛋白质的基本结构单元.α-氨基酸锌作为添加剂在药物、食品和化妆品中有广阔的应用前景[1～3].L-α-亮氨酸(简写为Leu)是人体必需但在人体内又不能合成的氨基酸之一,必须从食物中得到.文献中尚未见亮氨酸锌的报导.本文用半微量相平衡方法[4]研究了ZnSO4-Leu-H2O体系在25℃的相化学行为,发现该体系中未形成新化合物.改进文献方法合成了未见文献报导的Zn(Leu)SO4·12H2O和Zn(Leu)2固态配合物,并研究了它们的物理化学性质.1实验部分1.1试剂与仪器　　Zn…     

A Plasma Surface Treatment of Polyester Textile Fabrics Used for Reinforcement of Car Tires

Polyester tire cord surfaces have been modified by plasma at low temperature and atmospheric pressure. The surface treatment has been executed by various nonequilibrium discharges, namely by barrier discharge, atmospheric pressure glow discharge and gliding arc. The polymeric multicord sewing threads treated by this procedure have been used in the same form as in industry, i.e., with the protecting oil films on their surface. The surface properties have been investigated by electron spin resonance spectroscopy and by measuring their contact angle with various liquids; partially the zeta potential measurements have been used, too. Further tests have been done at an industrial testing impregnation line using the common technology and conditions, on both plasma treated and untreated fibers. Finally, the standard H-tests and peel-tests have been used to characterize the fiber adhesion to usual testing rubbers.     

Field determination of rhenium in plants using catalytic test methods with dimethyldithiooxamide and Sulfonitrazo P

Methods for the field determination of rhenium in plants have been developed. The speciation of rhenium in solutions throughout the process of sample preparation has been investigated. It has been shown that, in the initial ethanol and water-salt extracts, rhenium occurs as perrhenate ions. Perrhenate ions have been established to be partially reduced in time to give Re(VI). Since test methods have been developed for determining rhenium as perrhenate-ions, their partial reduction in the process of sample preparation can lead to an low level of the results. The optimal conditions for preserving rhenium as perrhenate ions have been determined. Two procedures (in four versions) providing the determination of as low as 5 ng of rhenium in a 1-g sample with an error below 23% have been proposed. The developed procedures have been applied in the places of the collection of plant materials for the regional investigation of the occurrence of rhenium in the territories of different ore contents.