导电高分子膜包覆YBa2Cu3O7超导体抗环境作用的研究

通过电化学途径和化学途径在ＹＢａ＿２Ｃｕ＿３Ｏ＿７超导体表面制备了导电高分子聚吡咯膜，用以保护超导体不受环境作用的影响，实验结果发现电化学过程能破坏ＹＢａ＿２Ｃｕ＿Ｏ＿７的超导性，而采用化学法制备的聚吡咯和聚氯乙烯混和材料包覆在ＹＢａ＿２Ｃｕ＿３Ｏ＿７表面后，超导体不仅保持原有超导性，而且有很好的保护超导体免遭环境中酸和水作用的能力。     

Binding of brucine to human serum albumin

The feature of brucine binding to human serum albumin (HSA) was investigated via fluorescence and UV/vis absorption spectroscopy. The results revealed that brucine caused the fluorescence quenching of HSA by the formation of brucine–HSA complex. The hydrophobic interaction plays a major role in stabilizing the complex; the binding site number n and apparent binding constant K_A, corresponding thermodynamic parameters the free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) at different temperatures were calculated. The distance r between donor (HSA) and acceptor (brucine) was obtained according to fluorescence resonance energy transfer. The effect of brucine on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and UV/vis absorption spectroscopy.     

Geometries and properties of bimetallic phosphido-bridged complex Cp(CO)2W(μ-PPh2)W(CO)5 and Cp(CO)3W(μ-PPh2)W(CO)5

Complete geometry optimizations were carried out by HF and DFT methods to study the molecular structure of binuclear transition-metal compounds (Cp(CO)₃W(μ-PPh₂)W(CO)₅) (I) and (Cp(CO)₂W(μ-PPh₂)W(CO)₅) (II). A comparison of the experimental data and calculated structural parameters demonstrates that the most accurate geometry parameters are predicted by the MPW1PW91/LANL2DZ among the three DFT methods. Topological properties of molecular charge distributions were analyzed with the theory of atoms in molecules. (3, −1) critical points, namely bond critical point, were found between the two tungsten atoms, and between W1 and C10 in complex II, which confirms the existence of the metal–metal bond and a semi-bridging CO between the two tungsten atoms. The result provided a theoretical guidance of detailed study on the binuclear phosphido-bridged complex containing transition metal–metal bond, which could be useful in the further study of the heterobimetallic phosphido-bridged complexes.     

Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.     

Solid state synthesis and structure of two novel polyoxometalates [(n-Bu)4N]4[M6O19][Ag2I4](M?Mo,W)†

The reaction of [NH₄]₂[MO₂S₂], AgI and (n-Bu)₄NBr in solid state produced the polyoxometalates [(n-Bu)₄N]₄[M₆O₁₉][Ag₂I₄] (1, M? Mo; 2, M? W) which were structurally determined. The crystals of 1 and 2 are isomorphous, monoclinic, space group P2₁/c. 1, a = l.6624(2), b=1.6699(3), c=l.7217(2) nm, β=98.29(1)°, V=4.729(1) nm³, Z=2, R=0.040, R_w“0.037; 2, a = 1.6636(3), b = 1.6733(3), c = 1.7190(3) nm, β=98.25(1)°, V=4.736(l) nm³, Z = 2, R = 0.038, R_w = 0.047. The results of the structure determination showed that the two compounds had the same structures whose skeletons are composed of [Ag₂I₄]². and [M₆O₁₉]^2-. The difference of them and heteropolymetalate compounds synthesized in solution is that the title compounds contain cluster. ion, heteropolymetalate and organic cations, while the latter is only composed of heteropolymetalate and organic cations.     

Studies of some new bioactive acrylic esters

Four typical bioactive esters of acrylic monomers, N-p-acryloxybenzoyloxysuccinimides, 3-ac-ryloxy-4-oxo-3,4-dihydro-1,2,3-benzotriazines, N-acryloxy-5-norbornene-2,3-dicarboximides, and I-p-acryloxybenzoyloxybenzotriazoles, were Synthesized and polymerized as reactive polymers. Twelve new monomers were prepared by coupling acrylic acid, methacrylic acid, p-acryloxybenzoic acid, or p-methacryloxybenzoic acid with four N-hydroxy compounds such as N-hydroxysuccinimide (HOSu), 3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine (HOObt), N-hydroxy-5-norbornene-2,3-dicarboximide (HONB), and I -hydroxybenzotriazole (HOBT) in the presence of dicyclohexylcarbodimide. All monomers polymerized readily in solution with azobisisobutyronitrile (AIBN) as free radical initiator. The resulting reactive polymers with reactive ? OSu, ? OObt, ? ONB, or ? OBT group on the side chain are equally reactive toward n-butylamine at room temperature in the formation of corresponding polyacrylamides. Reactive polymers were used to immobilizetrypsin. It has been found that poly(N-p-methacryloxybenzoyloxy-5-norbornene-2,3-dicarboximide)-trypsin matrix had high activity around three times that of the poly(N-methacryloxy-5-norbornene-dicarboximide)-trypsin matrix. It is proposed that this activity may be due to the presence of a long spacer arm with a hydrophobic and rigid benzene ring between the ligand and matrix. The reactive poly(N-p-methacryloxybenzoyloxysuccinimide-p-methacryloxybenzoic acid) copolymer was used to immobilize the serum protein. This immobilized protein was a hopeful bioactive solid immunoadsorbent.     

漆树漆酶的催化氧化作用——Ⅳ.二茂铁及其衍生物的酶促氧化

In phosphate buffer-diethylene glycol monobutyl ether(DGBE), the oxidations of ferrocene and 15 derivatives were investigated in the presence of Rhus vernicifera laccase. The results showed that ferrocene and 11 derivatives can be oxidized. The mechanism of Laccase catalyzed oxidation of ferrocene was put forward.     

The Chemical Constituents from the Aerial Part of Rosa laevigata

Eleven chemical constituents were isolated from the ethyl acetate soluble fraction of the aerial part of Rosa laevigata Michx. These compounds include the Henze's ketol (16), diethyl malate (17), three γ-lactones (18-20), loliolide (21), p-coumaric acid (22), 6,7-dimethoxycoumarin (23) and three flavonoids (24-26). The new compounds 19 and 20 were determined to be the cis- and trans-isomers of ethyl 2-benzyl-3-hydroxy-5-oxo-3-furancarboxylate.     

Anisotropic hydrogel thickness gradient films derivatized to yield three-dimensional composite materials

We report the preparation of in-plane density gradients of amino-terminated molecules and gold particles through derivatization of laterally varying thickness gradients of poly(acrylic acid) (PAA) or poly(acrylamide) (PAAm) films. PAA and PAAm gradients were formed by Zn(II)-catalyzed electropolymerization of acrylic acid (AA) or acrylamide (AAm) in the presence of an in-plane electrochemical potential gradient applied to Au or indium-tin-oxide (ITO) working electrodes. PAA thickness gradients were converted into density gradients of fluorocarbons or biocompatible groups by derivatizing with NH(2)CH(2)(CF(2))(6)CF(3) or an Arg-Gly-Asp (RGD)-containing peptide, respectively. X-ray photoelectron spectroscopy (XPS) and XPS imaging were used to characterize the modified PAA gradients. Transition regions as narrow as 104 mum were achieved for fluorocarbon gradients. PAAm gradients were treated with gold particles to form a density gradient of gold particles. Surface plasmon resonance imaging and scanning electron microscopy (SEM) as well as UV-visible absorption measurements were used to characterize the gold particle density gradients. It is likely that the gold particles were attached both on the surface and inside the PAAm film.     

1,2,2,6,6-五甲基哌啶醇对聚丙烯光稳定作用的研究

<正> 关于受阻胺类光稳定剂的稳定作用机理,是近年来光稳定研究领域中广泛探讨的课题,我们用异辛烷溶液研究了1,2,2,6,6-五甲基哌啶醇的光稳定作用,结果已在前文报道,本工作是上述研究的继续,主要研究五甲基哌啶醇对聚丙烯膜的光稳定作用。