用过渡金属络合催化剂在水介质中引发烯烃单体的配位聚合

介绍了乙烯、丁二烯和苯乙烯等单体在水介质中用过渡金属络合催化剂合成有规立构聚合物 的研究进展,详细阐述了钴系催化剂在水介质中合成间同1, 2 - 聚丁二烯的研究成果。

Study on the instability of organic field-effect transistors based on fluorinated copper phthalocyanine

The effects of positive and negative gate-bias stress on organic field-effect transistors (OFET) based on tantalum (Ta)/tantalum pentoxide (Ta2O5)/fluorinated copper phthalocyanine (F16CuPc) structure are investigated as a function of stress time and stress temperature. It is shown that gate-bias stress induces a parallel threshold voltage shift (DeltaV(T)) of OFETs without changes of field-effect mobility mu(EF) and sub-threshold slope (DeltaS). The DeltaV(T) is observed to be logarithmically dependent on time at high gate-bias appropriate to OFET operation. More importantly, the shift is directional, namely, be large shift under positive stress and almost do not move under negative stress. The threshold voltage shift is temperature dependent with activation energy of 0.51 eV We concluded that threshold voltage shift of the OFET with F16CuPc as active layer is due to charge trapping in the insulator in which trapped carriers have redistribution.

Differential proteomic analysis of neonatal cardiomyocytes in response to beta-adrenergic receptor stimulation

beta-Adrenoceptors(beta-ARs) play a critical role in regulating cardiac functions under both physiological and pathological conditions. To further explore the mechanisms through which beta-ARs perform its actions, proteomic approaches were adopted to study the global protein patterns in cultured neonatal rat cardiomyocytes exposed to isoproterenol (ISO). A modified method, "Mirror Images in One Gel", was used to improve the reproducibility and resolution power of two-dimensional electrophoresis. A 2-DE map with a good reproducibility was obtained in which 1281 70 spots were detected and about 1191 +/- 54 spots were matched, with an average matching rate of 92.9%. Nine proteins with significant changes were identified by using peptide mass fingerprinting(PMF) data obtained via MALDI-MS.

N,N-二甲基甲酰胺存在下块状TiO_2凝胶的制备

在 Ｎ，Ｎ－二甲基甲酰胺（ＤＭＦ）存在下，研究了钛酸丁酯的水解缩聚过程，考察了酸及 ＤＭＦ用量对水解速率的影响。结果表明，随酸和 ＤＭＦ用量的增加，胶凝时间变长。通过 ＴＧ－ＤＴＡ的测定和Ｘ射线衍射分析，表明ＴｉＯ２胶粉末在５００℃时已转变成锐钛矿结构，６００℃时锐钛矿与金红石结构两相并存，到８００℃时全部转化为金红石结构。

Barrier properties of vinylidene chloride methyl acrylate copolymer

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) as comonomer (3-12wt%), was prepared by free-radical suspension copolymerization. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor were measured at 30 degrees C and 100% relative humidity. All the VDC/MA copolymers studied are semicrystalline. As the MA content increases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, and water vapor are progressively increased, caused by decrease in crystalline fraction and increase in free volume of VDC/MA copolymers.

Luminescence and energy transfer phenomena of several rare earth ions in the CaAl2B2O7

The luminescence properties of Ce3+, Gd3+, and Tb3+ have been investigated in the compound CaAl2B2O7. The single excitation band peaking at about 320 nm and single emission band peaking at about 384 nm for Ce3+, without the characteristic doublet, are attributed to the extensive crystal-field splitting of 4f ground state. The emission of Gd3+ consists of well-known sharp lines and two weak bands around 319.5 and 325 nm. These bands are due to the coupling of Gd3+ with BO33- groups. The green emission of Tb3+ is considerably sensitized by Ce3+. Energy transfer from Ce3+ to Tb3+ in CaAl2B2O7 is efficient. (C) 1997 Elsevier Science Ltd.

稀土离子及其配合物与磷脂脂质体的相互作用

用核磁共振(NMR)方法研究了稀土离子及其配合物与二棕榈酰磷脂酰胆碱(DPPC)和鞘磷脂(SPM)脂质体的相互作用.磷脂极性头平行于膜平面.稀土离子与磷脂极性头P—O键键合,与经典模型不同,键合后极性基团仍平行于膜平面,而不是垂直于膜平面.稳定的稀土配合物对磷脂脂双层结构影响很小.将稀土离子引入磷脂脂质体和小分子配体的混合物中,稀土首先与小分子配体配位.

Cyro-hydrogel for the construction of a tyrosinase-based biosensor

A new immobilization method for construction of a tyrosinase based biosensor is described. A simple physical freezing technique was adopted for preparation. The immobilized enzyme yields specific activities that are more than 22% of the soluble enzyme. The enzyme electrode can be stored in dry state for more than three months without any loss of activity. The biosensor was applied to the determination of several phenols and o-diphenols. The lowest detect limit is 0.02 mu mol/1 and the linear range was 1.0 X 10(-7)-1.0 X 10(-4) mol/1 for catechol. The kinetic parameters have also been calculated.

OBSERVATION OF EU2+ AND TB4+ IN SRMG4-EU8+, TB8+

Europium(II) and terbium(LV) drive boon observed in SrMgF4: Eu3+, Tb5+ phosphors which are synthesized in Ar stream. The valence state of europium is influenced by terbium. It is notable that the intensities of electron paramagnetic resonance (EPR) peaks corresponding to Eu2+ are increased when Tb3+ ion is incorporated in SrMgF4:Eu3+ phosphors, while X-ray photoelectron spectra of Tb-8d5/2 in SrMgF4:Eu3+,Tb3+ shows an additional peak at high energy to that of Tb-3d5/2 in SrMgF4: Tb3+, which is due to Tb4+. These phenomena can be explained by an electron transfer mechanism.

SYNTHESIS AND STRUCTURE CHARACTERIZATION OF LANTHANUM [2,2,2]CRYPTATES, [LACL[2,2,2](H2O)]CL-2-CENTER-DOT-H2O AND [LA(CF3SO3)[2,2,2]1(DMF)](CF3SO3)(2)

Two lanthanum(III) [2,2,2]cryptates, [LaCl[2,2,2](H2O)]Cl-2.H2O (1) and [La(CF3SO3)[2,2,2](DMF)] (CF3SO3)(2) (2) have been prepared by the reaction of LaCl3 and La(CF3SO3)(3) with [2,2,2]cryptand, respectively and their crystal structures have been determ

流动注射-分光光度法测定植物中钼

本文将流动注射分析(FIA)引入Mo-SCN~--RhB三元缔合体系测定痕量Mo。不需萃取,反应迅速,重现性好。0～1.6μg/ml Mo符合比耳定律,检测限0.02μg/ml。用预混线圈R_1可克服Fe~(3+)等元素与SCN~-络合的干扰。测定了植物中Mo,结果满意。

REEVALUATION OF 2,2-BIPYRIDINE AND PYRAZINE AS PROMOTERS FOR DIRECT ELECTRON-TRANSFER BETWEEN CYTOCHROME-C AND METAL-ELECTRODES

Results from previous electrochemical studies have indicated that 2,2'-bipyridine and pyrazine do not function as promoters for heterogeneous electron transfer between cytochrome c and metal electrodes. Their lack of activity was attributed to the improper positioning of the two functional groups in 2,2'-bipyridine and the inefficient length of pyrazine. In the present study it was determined that both 2,2'-bipyridine and pyrazine act as promoters when self-absorbed over a sufficiently long dipping time or at roughened electrodes. The promoter characteristics of these two molecules were studied and compared with those of 4,4'-bipyridine. The difference in their promoter behavior appears to result primarily from their different strengths of adsorption and not because electrodes modified with 2,2'-bipyridine or pyrazine are unsuitable for accelerating direct electron transfer reactions in cytochrome c. These results have implications regarding the mechanism(s) of promoter effects in electrochemical reactions of cytochrome c.

EASTMAN-AQ/NIII MODIFIED ELECTRODE CHARACTERIZATION AND APPLICATION IN FLOW-INJECTION DETERMINATION OF CARBOHYDRATES AND AMINO-ACIDS

A novel Eastman-AQ/Ni(II) chemically modified electrode (CME) produced by "double coating step" deposition of a poly(ester sulphonic acid) polymer film and Ni2+-containing crystalline species onto glassy carbon instead of a metallic nickel electrode exhibited stable electrocatalytic oxidation of numerous alpha-hydrogen compounds including carbohydrates, amines and amino acids. In cyclic voltammetry, the electrocatalysis appeared with an irreversible anodic wave at +0.55 V (vs. Ag/AgCl). The CME was adapted for constant-potential amperometric detection of these compounds in flow injection analysis. Using the CME, the linear response concentration range was between 1.0 x 10(-5) and 5.0 x 10(-2) mol/l and the detection limit was 5.0 x 10(-6) mol/l for glucose. The stability of the CME was adequate for routine quantitative application.

热处理四苯基钴卟啉修饰玻碳电极电催化氧化肼及其流动注射检测

肼是较难氧化的物质,在酸性溶液中,在碳电极上电化学检测要求检测电位正于1.0V.用董绍俊等报道的方法,我们在750℃下对四苯基钴卟啉修饰玻碳电极热处理1h,制得修饰电极(简称HCME).首次发现这种HCME在酸性溶液中对肼具有良好的电催化氧化作用和极高的催化稳定性. 循环伏安实验发现,在pH2.5的磷酸缓