Mn-containing AlPO-11 and SAPO-11 catalysts for simultaneous isomerization and dehydrogenation of n-butane

MnAPO-11 and MnAPSO-11 were synthesized hydrothermally, and supported Mn-AlPO-11 and Mn-SAPO-11 were also prepared for comparison. Characterization results showed that there were differences in acidity and reducibility caused by the different incorporation methods of manganese. The manganese species in the samples also weakened the metallic properties of the palladium particles when the latter was added into the catalysts. Catalytic testing results for dehydroisomerization of n-butane indicated that incorporation of manganese increased the selectivity toward isomerization products. The highest isobutene selectivity (34.86%) could be obtained over a Pd/MnAPO-11 catalyst. When a combined catalyst system containing Pd/SAPO-11 and MnAPSO-11 was used in a single bed of two layers, the isobutene selectivity could be greatly improved, as compared to the single catalyst alone.

固氮酶金属原子簇对其结构和功能的影响

一、 △nifZ MoFe蛋白的纯化、特性及晶体生长 从缺失nifZ的棕色因氮菌突变种DJ194中，经离子交换层析和凝胶过滤提纯得到△nifZ MoFe蛋白，其纯度可达SDS凝胶电泳纯。它的Fe、Mo含量分别为野生型OP MoFe蛋白的56.6%和75.0%左右;C_2H_2、H~+还原活性和△H_2均只有OP MoFe蛋白的14.6%、21.7%和21.7%;其可见吸收光谱、CD及AR谱都与OP MoFe蛋白有较大差异，其中，可以反应P-cluster氧还状态和含量的ε_(450nm)、ε_(700nm)及△ε_(450nm)均要比OP MoFe蛋白低;由紫外CD谱反映的△nifZ MoFe蛋白的构象也与OP MoFe蛋白有所不同。由此我们推测，nifZ可能与固氮酶MoFe蛋白中P-cluster的合成或组装有关。为进一步阐明△nifZ MoFe蛋白的结构和功能特性，我们对△nifZ MoFe蛋白的晶体生长进行了研究，通过对沉淀剂浓度、缓冲体系和pH、蛋白浓度以及温度等条件的不断优化组合，目前我们已获得棕色短斜四棱柱形△nifZ MoFe蛋白的最大晶体为0.15 * 0.09mm。 二、 MoFe(C,O)与含Mo、Mn和Cr重组液重组的比较研究 MoFe(R)经O_2和o-phen共同处理后，成为部分缺失FeMoco和P-cluster的不全蛋白(MoFe(C,O))，其C_2H_2还原活性降至MoFe(R)的40%左右，将其分别与含Mo、Cr和Mn的重组液进行保温重组，其C_2H_2还原活性及光谱学特征都得到明显恢复。通过对不同重组液及与MoFe(C,O)形成的重组蛋白的比较，我们认为：1)MoFe(R)中的Fe和Mo原子可能是逐步被鳌合除去的，且不同蛋白中的Fe和Mo原子的缺失程度不同，因而MoFe(C,O)会以多种状态存在;2)在重组液配制过程中，发生的一系列颜色变化及沉淀反应与其是否具有重组激活能力具有相关性，重组液中可能已合成一些简单的含M(M=Mo或Cr或Mn或V)的铁硫化物，但不可能形成完整的金属原子簇;3)含M(M=Mo或Cr或Mn)的重组液均能使MoFe(C,O)中遭到破坏的FeMoco和P-cluster及其连接部分得以重新组装和修复，进而恢复其底物还原活性和光谱学特征。 三、 含锰固氮酶的初步探索 棕色固氮菌突变种UW_3(nifH~-)不能在含钼的培养中固氮生长，但能在含MnSO_4的无氮培养基中固氮生长。用含MnSO_4的无钼无氮培养基培养该突变种从中纯化得到的固氮酶组分1蛋白，其C_2H_2及H~+还原活性约相当于MoFe(R)的20%左右，Mn元素含量测定表明，其中已经含有Mn元素，Fe/Mn比值比OP MoFe蛋白中的Fe/Mo低。这些结果表明：UW_3突变种在该种条件下可能已表达了不同于已发现的三种固氮酶的新的固氮酶组分1蛋白，并且其中含有Mn元素。

Covalently attached multilayer assemblies containing photoreactive diazo-resins and conducting polyaniline

We reported on the multilayer architecture containing diazo-resins (DAR) as polycations and polyaniline poly(aniline-co-N-propanesulfonic acid aniline) (PAPSAH) as polyanions held together by electrostatic interaction. Upon UV irradiation, the adjacent interfaces of the multilayer reacted to form a covalently crosslinking structure which greatly improved the stability of the films as confirmed by solvent etching experiments. These changes were confirmed by UV-Vis and FTIR spectroscopy. The thickness of the covalently attached films were characterized with small angle X-ray diffraction (SAXD) and a value of 30.0 Angstrom per bilayer was obtained. This type of film was further characterized by cyclic voltammetry which showed that the electroactive property of PAPSAH was still kept in the films after photoreaction. (C) 2000 Elsevier Science B.V. All rights reserved.

NR2B-containing N-methyl-D-aspartate subtype glutamate receptors regulate the acute stress effect on hippocampal long-term potentiation/long-term depression in vivo

Behavioral stress facilitates long-term depression but impairs long-term potentiation in the hippocampus. Recent evidence in vitro demonstrates that the NIR2B-containing N-methyl-D-aspartate subtype glutamate receptor antagonist Ro25-6981 prevents the beh

Characterization of metal-containing molecular sieves and their catalytic properties in the selective oxidation of cyclohexane

Three types of metal-containing molecular sieves with AFI, AEL and CHA structures (Me = Co, Mn, Cr and V) were synthesized hydrothermally and characterized by XRD, XRF, TG, TPR, NH3-TPD and FT-IR. It was revealed that metals were incorporated into the framework of molecular sieves and induced the presence of charge centers. Both cobalt and manganese in the framework of AIPO-5, AlPO-11 and SAPO-34 were not reducible before the structure collapse. The redox behaviours of these catalysts in cyclohexane oxidation at 403 K using O-2 as oxidant were examined. CoAPO-11 exhibited best activity and good selectivities for the monofunctional oxidation products (88.5%). Cyclohexanol was the major product over most catalysts, whereas for Cr-containing molecular sieves, high selectivity of cyclohexanone was observed. Investigation of reaction mechanism based on CoAPO-11 and CrAPO-5 catalysts indicated that the decomposition of cyclohexyl hydroperoxide (CHHP), the intermediate in cyclohexane oxidation, followed the pathway: cyclohexanone <-- CHHP --> cyclohexanol -->cyclohexanone. (C) 2004 Elsevier B.V. All rights reserved.

Novel acid-base polyimides synthesized from binaphthalene dianhydrie and triphenylamine-containing diamine as proton exchange membranes

The synthesis and characterization of novel acid-base polyimide membranes for the use in polymer electrolyte membrane fuel cell is presented in this paper. The sulfonated polyimides (SPIs) bearing basic triphenylamine groups were easily synthesized using 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BTDA), sulfonated diamine of 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS), and nonsulfonated diamines of 4,4'-diaminotriphenylamine (DATPA). The effects of the structure of the dianhydride and diamines on the properties of SPI membranes were evaluated through the study of membrane parameters including water sorption, proton conductivity, water stability, dimensional changes, and methanol permeability.

Naphthalene-Based Poly(arylene ether ketone) Copolymers Containing Sulfobutyl Pendant Groups for Proton Exchange Membranes

A new monomer 1,5-bis(4-fluorobenzoyl)-2,6-dimethoxynaphthalene (DMNF) was prepared and further polymerized to form naphthalene-based poly(arylene ether ketone) copolymers containing methoxy groups (MNPAEKs). The side-chain-type sulfortated naphthalene-based poly(arylene ether ketone) copolymers (SNPAEKs) were obtained by demethylation and sulfobutylation. Flexible and tough membranes with reasonably high mechanical strength were prepared. The SNPAEKs membrane showed anisotropic membrane swelling with larger swelling in thickness than in plane. Transmission electron microscopy (TEM) analysis revealed clear nano-phase separated structure of SNPAEKs membranes, which composed of hydrophilic side chain and hydrophobic main-chain domains.

Electrostatic interaction hybrids from water-borne conductive polyaniline and inorganic precursor containing carboxyl group

Electrostatic interaction conductive hybrids were prepared in water/ethanol solution by the sol-gel process from inorganic sol containing carboxyl group and water-borne conductive polyaniline (cPANI). The electrostatic interaction hybrids film displayed 1-2 orders of magnitude higher electrical conductivity in comparison with common hybrids film, showing remarkable conductivity stability against water soaking. Most strikingly, it displayed ideal electrochemical activity even in a solution with pH = 14, which enlarged the conducting polyaniline application window to strong alkaline media.

Water-resistant conducting hybrids from electrostatic interactions

Conductive hybrids were prepared in a water/ethanol solution via the Solgel process from an inorganic sol containing carboxyl groups and water-borne conductive polyaniline (cPANI). The inorganic sol was prepared by the hydrolysis and condensation of methyltriethoxysilane with the condensed product of maleic anhydride and aminopropyltriethoxysilane as a catalyst, for which the carboxyl counterion along the cPANI backbone acted as an electrostatic-interaction moiety. The existence of this electrostatic interaction could improve the compatibility of the two components and contribute to the homogeneous dispersion of cPANI in the silica phase. The electrostaticinteraction hybrids displayed a conductivity percolation threshold as low as 1.1 wt % polyaniline in an emeraldine base, showing 2 orders of magnitude higher electrical conductivity than that without electrostatic interactions. The electrostatic-interaction hybrids also showed good water resistance; the electrical conductivity with a cPANI loading of 16 wt % underwent a slight change after 14 days of soaking in water.

Electroactive oligoaniline-containing self-assembled monolayers for tissue engineering applications

A novel electroactive silsesquioxane precursor, N-(4-aminophenyl)-M-(4'-(3-triethoxysilyl-propyl-ureido) phenyl-1,4-quinonenediimine) (ATQD), was successfully synthesized from the emeraldine form of amino-capped aniline trimers via a one-step coupling reaction and subsequent purification by column chromatography. The physicochemical properties of ATQD were characterized using mass spectrometry as well as by nuclear magnetic resonance and UV-vis spectroscopy. Analysis by cyclic voltammetry confirmed that the intrinsic electroactivity of ATQD was maintained upon protonic acid doping, exhibiting two distinct reversible oxidative states, similar to polyaniline. The aromatic amine terminals of self-assembled monolayers (SAMs) of ATQD on glass substrates were covalently modified with an adhesive oligopeptide, cyclic Arg-Gly-Asp (RGD) (ATQD-RGD). The mean height of the monolayer coating on the surfaces was similar to 3 nm, as measured by atomic force microscopy. The biocompatibility of the novel electroactive substrates was evaluated using PC12 pheochromocytoma cells, an established cell line of neural origin. The bioactive, derivatized electroactive scaffold material, ATQD-RGD, supported PC12 cell adhesion and proliferation, similar to control tissue-culture-treated polystyrene surfaces.

A room-temperature ionic-liquid-templated proton-conducting gelatinous electrolyte

Novel proton-conducting gelatinous electrolytes templated by room-temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium-tetrafluoroborate (BMImBF(4)) have been prepared in methylsisesquioxane backbone containing H3PO4, and the influences of the RTIL on the structure, morphology, thermal stability, and electrochemical properties of the gelatinous electrolytes have been examined. X-ray diffraction and scanning electron microscopy proved that BMImBF(4) acted as structure-directing template during the sol-gel process of methyl-trimethoxysilane. X-ray photoelectron spectra and infrared spectroscopy demonstrated that the hydrogen-bonding was formed between BMImBF(4) and H3PO4. The electrolytes had good thermal stability up to 300 degreesC and showed superior mechanical and electrochemical properties. A room-temperature conductivity of 1.2 x 10(-3) S cm(-1) was obtained for the electrolyte at the molar ratio of RTIL/Si/H3PO4 0.3/1/1, and its electrochemical window was up to 1.5 V.

Design, synthesis and characterization of novel nitrogen-and sulfur-containing polymers with well-defined conjugated length

A series of novel nitrogen- and sulfur-containing conjugated polymers with well-defined conjugation length have been synthesized via an acid-induced self-polycondensation of functional monomers with methylsulfinyl groups. Synthesized polymers exhibit good solubility in common solvents, such as CHCl3, THF, DMF, DMSO, and NMP. With increased numbers of aminophenyl groups, these polymers have shown similar electrical properties to polyaniline (PAn), and these are demonstrated by UV-vis spectroscopy and cyclic voltammetry (CV) measurements on the polymers. The conductivity of preliminarily protonic-doped poly[phenylene sulfide-alt-tetrakis(aniline)] (PPSTEA) is up to 10(-1) S cm(-1).

Stimulated emission in the blue wavelength region from a copolymer containing PPV segment

The lasing properties of a soluble conjugated polymer, Poly[1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,2-phenylene-1,2-ethenylene-3,5-dimethoxy-1,4-phenylene] (CNMBC-Ph) in chloroform solution were investigated. The third harmonic radiation of a Nd:YAG laser was used as the pump light. The stimulated emission with a linewidth of 15 nm was observed in the blue wavelength region with the peak at 450 nm. The threshold pulse peak power was about 2.8 MW/cm(2). The energy conversion yield of the laser was estimated to be about 3.4%. The maximum peak power of the laser output pulse reached 40 kW. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Poly(phenylene sulfide-tetraaniline): The soluble conducting polyaniline analogue with well-defined structures

A novel conducting polymer poly(phenylene sulfide-tetraaniline) (PPSTEA), with tetraaniline (TA) and phenylene sulfide (PS) segments in its repeat unit, has been synthesized through an acid-induced polycondensation reaction of 4-methylsulfinylphenyl-capped tetraaniline. The new polymer, which represents the first soluble conducting polyaniline analogue with well-defined structure, has high molecular weight, good solubility in common solvents, and good film-forming properties. Its electrical property is analogous to polyaniline. The conductivity of preliminarily, protonic-doping PPSTEA is up to 10 degrees S/cm. This synthetic strategy appears to be general for developing novel well-defined polyaniline analogue containing much longer fixed conjugation length.