STRUCTURE EVOLUTION OF POLYMER CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

Finite element method is used to simulate the high-speed melt spinning process,based on the equation system proposed by Doufas et al.Calculation predicts a neck-like deformation,as well as the related profiles of velocity,diameter, temperature,chain orientation,and crystallinity in the fiber spinning process.Considering combined effects on the process such as flow-induced crystallization,viscoelasticity,filament cooling,air drag,inertia,surface tension and gravity,the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions.The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated.Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed,giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.     

LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS： EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene （LDPE）, ethylene copolymer and organoclay. X-ray diffraction （XRD） and transmission electron microscopy （TEM） were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.     

Factors affecting the catalytic epoxidation of olefins by iron porphyrin complexes and H2O2 in protic solvents

The catalytic epoxidation of cyclohexene by iron(III) porphyrin complexes and H2O2 has been investigated in alcohol solvents to understand factors affecting the catalyst activity in protic solvents. The yields of cyclohexene oxide and the Fe(III/II) reduction potentials of iron porphyrin complexes were significantly affected by the protic solvents, and there was a close correlation between the product yields and the reduction potentials of the iron porphyrin catalysts. The role of alcohol solvents was proposed to control the electronic nature of iron porphyrin complexes that determines the catalyst activity in the epoxidation of olefins by H2O2. We have also demonstrated that an electron-deficient iron porphyrin complex can catalyze the epoxidation of olefins by H2O2 under conditions of limiting substrate with high conversion efficiency in a solvent mixture of CH3OH and CH2Cl2.     

毛细管区带电泳法测定血浆中的苯妥英钠

 建立了以毛细管区带电泳测定血浆中苯妥英钠含量的方法。此法具有良好的重现性和线性关系 ,日内、日间的平均相对标准偏差分别为 3.1%和 4 .7% ,平均回收率大于 95 % ,标准曲线的相关系数为 0 9985 ,是一种简便、快速、准确、灵敏的测定方法 。     

化妆品及香精中27种香料的气相色谱-质谱检测方法

建立了气相色谱-质谱同时检测化妆品及香精中27种香料的方法。采用甲醇作为提取溶剂，经弱极性毛细管柱分离，用气相色谱-质谱检测，离子源为电子轰击离子（EI）源。该方法对麝香二甲苯、羟基香茅醛和羟异己基3-环己烯基甲醛的检出限分别为1.2、15和15 mg/kg，其余香料的检出限为3.0 mg/kg。27种香料在相应的线性范围内线性关系良好，相关系数均大于等于0.996。在3个加标浓度下，麝香二甲苯的回收率为73.3%~76.1%，其余为81.5%~118%，相对标准偏差小于10%。采用建立的方法对69份香精或标示含香料化妆品进行检测，全部样品都检测出含有一种或多种香料。该方法适用于化妆品及香精中27种香料的测定。     

Two new megastigmane O-glucopyranosides from the leaves of Broussonetia papyrifera

Two new megastigmane O-glucopyranosides,named (2R,3R,5R,6S,9R)-3-hydroxy-5,6-epoxy-β-ionol-2-O-β-D-glucopyrano- side(1) and (2R,3R,5R,6S,9R)-3-hydroxyl-5,6-epoxy-acety-β-ionol-2-O-β-D-glucopyranoside(2) together with six known mega- stigmanes,were isolated from the leaves of Broussonetia papyrifera (Linn.) Vent.Their structures were established by chemical methods and spectroscopic techniques including 2D NMR.     

Multilayer vesicles and vesicle clusters formed by the fullerene-based surfactant C60(CH3)5K

The self-assembly behavior of a fullerene-based surfactant, C60(CH3)5K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C60(C6H5)5K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes of C60(CH3)5K (radius R approximately 26.8 nm) and C60(C6H5)5K (R approximately 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C60(CH3)5K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R approximately 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles.     

Synthesis and optical resolution of a series of inherently chiral calix[4]crowns with cone and partial cone conformations

A series of inherently chiral calix[4]arenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)-BINOL to form diastereomers which, in most cases, could be separated by preparative TLC, or more desirably, by column chromatography on silica gel (diastereomeric excess >99 % based on HPLC analysis). Seven enantiopure antipodes of inherently chiral calix[4]crowns were obtained after hydrolysis. It has been found that both the size of the crown moiety and alkylation of the last phenolic hydroxy group (accompanied with or without a change in the conformation) affect the separation of the diastereomers.     

Gold complexes with potentially tri- and tetradentate phosphinothiolate ligands

Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-R-3)2 (H2L1a, R = SiMe3; H2L1b, R = H) and P(C6H4-SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained, which contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) and 3.434(1) A). They are indicative of weak gold-gold interactions, which is unusual for gold(III).     

Study on the Binding Effect between Cordycepin and Calf Thymus DNA by Circular Dichroism

DNA works as hereditary material and plays vital role in life science. The study of the binding of small molecules complex to DNA has been the focus of intense investigation, owning to their stereo and sequence specific interaction with the double helix1-…