A novel route to polyethylene-polystyrene blends through the fragmentation of porous polystyrene beads supported metallocene in ethylene polymerization

Polyethylene-polystyrene blends were synthesized by in situ ethylene polymerization with polystyrene porous beads supported metallocene; the influence of fragmenting support beads on the morphology and the mechanical performance of the blends was investigated.

NMR and pattern recognition studies on the acute biochemical effects of Lu(NO3)(3)

Pattern recognition methods were applied to the analysis of 600 MHz H-1 NMR spectra of urine from rats dosed with compounds that induced organ-specific damage in the liver and kidney. Male Wistar rats were separated into groups (n=4) and each was treated with one of following compounds: HgCl2, CCl4, Lu(NO3)(3) and Changle (a kind of rare earth complex mixed with La, Ce, Pr and Nd). Urine samples from the rats dosed with HgCl2, CCl4 and Lu(NO3)(3) were collected over a 24 h time course and the samples from the rats administrated with Changle were gained after 3 months. These samples were measured by 600 MHz NMR spectroscopy. Each spectrum was data-processed to provide 223 intensity-related descriptors of spectra. Urine spectral data corresponding to the time intervals, 0-8 h (HgCl2 and CCl4), 4-8 (Lu(NO3)(3)) h and 90 d (Changle) were analyzed using principal component analysis (PCA). Successful classification of the toxicity and biochemical effects of Lu(NO3)(3) was achieved.

Conformational changes of beta-lactoglobulin induced by anionic phospholipid

Conformational changes of beta-lactoglobulin (beta-LG) induced by anionic phospholipid (dimyristoylphosphatidylglycerol, DMPG) at physiological conditions (pH 7.0) have been investigated by UV-VIS, circular dichroism (CD) and fluorescence spectra. The experimental results suggest that beta-LG-DMPG interactions cause beta-LG a structural reorganization of the secondary structure elements accompanied by an increase in alpha-helical content, and a loosening of the protein tertiary structure. The interaction forces between beta-LG and DMPG are further evaluated by fluorescence spectra. The fluorescence spectral data show that conformational changes in the protein are driven by electrostatic interaction at first, then by hydrophobic interaction between a protein with a negative net charge and a negatively charged phospholipid.

Luminescence and energy transfer of Ce3+ and Tb3+ in Y3Si2O8Cl

The luminescence properties of Ce3+ and Tb3+ in Y3Si2O8Cl have been investigated. The Ce3+ excitation bands in the region from 220 to 360 run are attributed to the transitions from 4f level to the crystal-field splitting levels of 5d.

Self-assembled multilayers of alternating gold nanoparticles and dithiols: approaching to superlattice

The preparation of self-assembled multilayers of alternating gold nanoparticles and dithiols on Si or SiO2 substrates coated with (3-aminopropyl) trimethoxysilane are reported. The superlattice structure of these self-assembled multilayers was demonstrated by the results of UV-Vis spectrometry, AFM and X-ray diffraction measurements. The multilayer assembled by small-size gold particles has good periodic structure. (C) 2000 Elsevier Science B.V. All rights reserved.

Correlation analysis of the structures and gas-liquid chromatographic retention indices of amines

Quantitative structure-retention relationship(QSRR) was studied for amines to gas-liquid chromatography on three stationary phases of different polarities with the topological indices A(m) (A(m1), A(m2), A(m3)) and gravitational index GI. The algorithm of "Leaps and Bounds" was performed for selection of the variables. And the multi-regression and the quasi-Newton neural networks were employed for the calculation with better results.

胺类化合物气相色谱保留指数与结构的相关性研究

应用Am指数和引力指数C1对在3种体系下的胺类化合物的气相色谱保留指数和结构进行了相关性研究，并运用最佳子变量集算法和人工神经网法进行了计算分析，在非极性固定相OV-101和极性固定相OV-225和NGA下均获得了比较好的相关模型。

High resolution solid-state NMR and DSC study of poly(ethylene glycol) silicate hybrid materials via sol-gel process

Hybrid materials incorporating poly(ethylene glycol) (PEG) with tetraethoxysilane (TEOS) via a sol-gel process were studied for a wide range of compositions of PEG by DSC and high resolution solid-state C-13- and Si-29-NMR spectroscopy. The results indicate that the microstructure of the hybrid materials and the crystallization behavior of PEG in hybrids strongly depend on the relative content of PEG. With an increasing content of PEG, the microstructure of hybrid materials changes a lot, from intimate mixing to macrophase separation. It is found that the glass transition temperatures (T-g) (around 373 K) of PEG homogeneously embedded in a silica network are much higher than that (about 223 K) of pure PEG and also much higher in melting temperatures T-m (around 323 K) than PEG crystallites in heterogeneous hybrids. Meanwhile, the lower the PEG content, the more perfect the silica network, and the higher the T-g of PEG embedded in hybrids. An extended-chain structure of PEG was supposed to be responsible for the unusually high T-g of PEG. Homogeneous PEG-TEOS hybrids on a molecular level can be obtained provided that the PEG. content in the hybrids is less than 30% by weight. (C) 1998 John Wiley & Sons, Inc.

The photophysical properties of binary and ternary complexes of rare earths with conjugated carboxylic acids and 1,10-phenanthroline

Results of photophysical properties of the complexes of Gd3+, Eu3+ and Tb3+ with conjugated carboxylic acids (3,4-funandicarboxylic acid and nicotinic acid) and 1,10-phenanthroline are reported. Whether between central ions and ligands or between the two ligands, it is found that the intramolecular energy efficiency is a sensitive function of the relative positions of the resonance energy levels of the central ions and the lowest triplet states of the ligands. Couplings of rare earth ions to the ligands are discussed in detail. (C) 1997 Elsevier Science S.A.

Synthesis and characterization of interpenetrating polymer networks based on polyacrylate and epoxy

The synthesis and properties of simultaneously interpenetrating networks (SINs) based on poly(polyethylene glycol diacrylate) (PEGDA) and epoxy (diglycidyl ether of bisphenol A, DGEBA) were studied. The effect of compositional variation on the morphology and properties of products was investigated. The swelling coefficient, densities, glass transition behavior, and thermal stability of these interpenetrating networks (IPNs) are discussed. Microphase separation morphological structures were found in all PEGDA/DGEBA IPNs. Decreased swelling ratios compared to the calculated swelling coefficients based on the weight additivity of the components were obtained after the formation of IPNs. Increased density and thermal stability were also obtained in these IPNs, implying the existence of interpenetration (topological entanglements) among the component networks.

镧系金属化合物催化苯乙烯和双烯烃的共聚──苯乙烯和异戊二烯共聚合制备高顺式－1，4嵌段共聚物

采用稀土催化体系Ｎｄ（Ｆ_３ＣＯ_２）_３－ＢｒＣ_５Ｈ_（１１）－Ｒ_ｍＡｌＨ_（３－ｍ）（Ｎｄ－Ｂｒ－Ａｌ），以甲苯为溶剂，在５０℃恒温水浴中进行苯乙烯（Ｓｔ）和异戊二烯（Ｉｐ）共聚合。结果表明，由Ａｌ（Ｏｃｔ）－３组成的催化体系可制备以顺式－１，４结构为主的共聚物；在后者组成的催化体系中，当Ａｌ／Ｎｄ＝５（摩尔比，下同），Ｂｒ／Ｎｄ＝５时，聚合活性最高。经ＩＲ，ＮＭＲ检测表征了共聚物的微观结构。同时，用π－烯丙基型配位机理和返扣配位机理对实验结果进行了定性解释。

AMPEROMETRIC DETECTION OF AMINO-ACIDS IN A FLOW-INJECTION SYSTEM WITH A NICKEL(II)-MODIFIED ELECTRODE WITH AN EASTMAN-AQ POLYMER FILM

Amperometic flow measurements were made at +0.55 V (vs. Ag/AgCl) in 0.1 mol l-1 KOH electrolyte with an Ni(II) chemically modified electrode (CME) with an Eastman-AQ polymer film. The use and characteristics of a Ni(II)-containing crystalline and polymer-modified electrode obtained by a double coating step as a detector for amino acids in a flow-injection system using reversed-phase liquid chromatography are described. The detection of these analytes is based on the higher oxidation state of nickel (NiOOH) controlled by the applied potential. The electroanalytical parameters and the detection current for a series of amines and amino acids were investigated. The use of such a CME in the flow-injection technique was found to be suitable in a solution at low pH. The linear range for glycine is 5 X 10(-6)-0.1 mol 1-1 with a detection limit of 1.0 X 10(-6) mol l-1. A 1 X 10(-4) mol 1-1 mixture of serine and tyrosine was also detected after separation on an Nucleosil C18 column.

ESTIMATION OF THE RADIATION-INDUCED DAMAGE IN PTFE BY DEPRESSION OF THE MELTING AND CRYSTALLIZATION TEMPERATURES

The radiation induced depression of the melting and crystallization temperatures of PTFE irradiated at various temperatures followed by heat treatment at 380-degrees-C, and their relationship to structural changes, were investigated. The G(-units) values obtained in this work are different from those of samples which have not undergone heat treatment and seem to be more closely associated with radiation induced branched structures.

烷烃异构体的结构排序与热力学性质的变化规律

应用分子链状片断(C—C—C,C—C—C—C,C—C—C—C—C)数P_2、P_3、P_4研究了烷烃异构体系列的结构排序及其热力学性质的规律性.每个烷烃分子表达为二维平面(mP_2+P_4,P_3)上的一个点(对辛烷,m=2,壬烷m=4,癸烷m=5),沿着坐标轴方向连结相同m点,得到相应烷烃的异构体周期表.在此基础上,提出了分子异构体序数的概念,并分析了多种热力学性质的变化趋势及其对结构的依赖关系.