Preparation, physico-chemical behavior and catalytic property for ammonia oxidation of perovskite like mixed oxides La2-xSrxCuO4-lambda

A series of Sr2+ doped perovskite like oxides La2-xSrxCuO4-lambda (x = 0 similar to 1) were prepared, the structure, lattice parameters, content of Cu3+, oxygen vacancies created by Sr2+ substitution and composition of these complex oxides were studied by XRD and iodic titration method. The redox ability,active oxygen species and surface image were evaluated and analyzed with TPD, TG, XPS and SEM measurements. The catalytic activity for ammonia oxidation over these oxides was tested, and the relationship among the catalytic properties, structure, nonstoichiometric oxygen,redox ability and surface behavior were correlated and some information on the mechanism of ammonia oxidation was obtained.

Gas transport property of homo- and copolyimides from isomeric thiaphthalic dianhydride and oxydianiline

Gas transport properties of home- and copolyimides prepared from 3,3',4,4'- and 2,2',3,3'-thiaphthalic dianhydride (p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former is lower than that of the latter. The permeability coefficients of m-TDPA-ODA to H-2, CO2, and O-2 are more increased by 48, 69 and 75%, at 30 degrees C and 10 atm, respectively, than those of p-TDPA-ODA; but the permselectivities of m-TDPA-ODA for H-2, CO2, and O-2 toward N-2 are more decreased by 33, 77, and 26%, respectively, than those of p-TDPA-ODA. The permeability coefficients and the diffusion coefficients of the copolyimides can be described by the following equations: log P = Phi(p) log P-p + Phi(m), log P-m and log D-a = D-a = Phi(p) log(D-alpha)(p) + Phi(m) log(D-a)(m), respectively. The variation of the permselectivity is controlled predominantly by diffusivity selectivity. These observations are interpreted in terms of variations in the fractional free volume of polyimides. (C) 1997 John Wiley & Sons, Inc.

Quantitative structure-property relationships for colour reagents and their colour reactions with cerium using computational neural networks

Quantitative structure-activity/property relationships (QSAR/QSPR) studies have been exploited extensively in the designs of drugs and pesticides, but few such studies have been applied to the design of colour reagents. In this work, the topological indices A(x1)-A(x3) suggested in this laboratory were applied to multivariate analysis in structure-property studies. The topological indices of 43 phosphone bisazo derivatives of chromotropic acid were calculated. The structure-property relationships between colour reagents and their colour reactions with cerium were studied using A(x1-Ax3) indices with satisfactory results. The purpose of this work was to establish whether QSAR can be used to predict the contrasts of colour reactions and in the longer term to be a helpful tool in colour reagent design.

Reactions of C-60 with R(3)SnH: A new synthetic route to C-60(RH)(n) and the property of C-60 to catalyze radical reactions

A new method for the preparation of polyalkyl and polyarenefullerene derivatives C-60(RH)(n)(R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C-60 with organotin hydride in toluene is described. Another series of products of stannanes R(a)Sn(b)H(c) (R=Bu, a=3-8, b=1-4, c=0-3 R=Ph, a=3-11, b=1-5, c=0-4) were also obtained, which shows that C-60 can catalyze polymerization of organic-tin. These products were determined by mass and infrared spectrometry. And the possible reaction mechanisms are discussed.

Studies on the adsorption property of NO on the Ni-based mixed oxide catalysts with Perovskite-like (ABO(3) and A(2)BO(4)) structure

The mixed oxides LaNiO3, La0.1Sr0.9NiO3, La2NiO4 and LaSrNiO4 with perovskite (ABO(3)) and related(A(2)BO(4)) structures were prepared and the adsorption property for NO and the catalytic activity for NO decomposition over these oxidse were also tested. The catalysts were characterized by means of BET surface measurement, chemical analysis, NO-TPD etc.. It was shown that the adsorption amount of NO is correlated with the concentration of oxygen vacancy formed and the adsorption type and strength of NO are related to the valence of metallic ion. Generally there are three kinds of adsorption species, NO-, NO+ and NO on the mixed oxides, among them the negative adsorpion species (NO-) are active for NO decomposition. The weaker the adsorption of oxygen on the catalyst is, the faster the mobility of oxygen is and the easier the redox process takes place in reproducing the active sites in which the oxygen species (O-, O2-) would participate.

In situ electrochemical scanning tunnelling microscopy investigation of structure for horseradish peroxidase and its electrocatalytic property

Immobilization of protein molecules is a fundamental problem for scanning tunnelling microscopy (STM) measurements with high resolution. In this paper, an electrochemical method has been proved to be an effective way to fix native horseradish peroxidase (HRP) as well as inactivated HRP from electrolyte onto a highly oriented pyrolytic graphite (HOPG) surface. This preparation is suitable for both ex situ and in situ electrochemical STM (ECSTM) measurements. In situ STM has been successfully employed to observe totally different structures of HRP in three typical cases: (1) in situ ECSTM reveals an oval-shaped pattern for a single molecule in neutral buffer solution, which is in good agreement with the dimension determined as 6.2 x 4.3 x 1.2. nm(3) by ex situ STM for native HRP; (2) in situ ECSTM shows that the adsorbed HRP molecules on HOPG in a denatured environment exhibit swelling globes at the beginning and then change into a V-shaped pattern after 30 min; (3) in situ ECSTM reveals a black hole in every ellipsoidal sphere for inactivated HRP in strong alkali solution. The cyclic voltammetry results indicate that the adsorbed native HRP can directly catalyse the reduction of hydrogen peroxide, demonstrating that a direct electron transfer reduction occurred between the enzyme and HOPG electrode, whereas the corresponding cyclic voltammograms for denatured HRP and inactivated HRP adsorbed on HOPG electrodes indicate a lack of ability to catalyse H2O2 reduction, which confirms that the HRP molecules lost their biological activity. Obviously, electrochemical results powerfully support in situ STM observations.

Quantitative structure-property relationships for colour reagents and their colour reactions with ytterbium using regression analysis and computational neural networks

In this paper, the new topological indices A(x1)-A(x3) suggested in our laboratory and molecular connectivity indices have been applied to multivariate analysis in structure-property studies. The topological indices of twenty asymmetrical phosphono bisazo derivatives of chromotropic acid have been calculated. The structure-property relationships between colour reagents and their colour reactions with ytterbium have been studied by A(x1)-A(x3) indices and molecular connectivity indices with satisfactory results. Multiple regression analysis and neural networks were employed simultaneously in this study.

Study on structure-property relationships between color reagents and sensitivity of color reactions with yttrium by topological indices

In this paper, three topological indices, Am-1, Am-2, and Am-3, multivariate analysis in structure-property studies. The topological indices of twenty asymmetrical phosphosphono bisazo derivatives of chromotropic acid have been calculated. The structure-property relationships between color reagents and molar absorptivity of color reactions with yttrium have been studied by A(m) indices and structure selective factors. Good results have been obtained by using correlation equation to predict the molar absorptivity of new color reagents.

Studies on structure-property relationship between color reagents and contrast of their color reactions with cerium by topological indices

In this paper, three topological indices A(m1), A(m2) and A(m3) have been applied to multivariate analysis in structure property relationship studies. The topological indices oi fourty-three asymmetrical phosphono bisazo derivatives of chromotropic acid have been calculated, The structure-property relationship between color reagents and contrast of color reactions with cerium has been studied by A, indices and structure selective factors, Good results have been obtained.

STRUCTURE-PROPERTY RELATIONSHIP BETWEEN HALF-WAVE POTENTIALS OF ORGANIC-COMPOUNDS AND THEIR TOPOLOGY

A significant correlation was found between half-wave potentials of organic compounds and their topological indices, A(x1), A(x2), and A(x3). The simplicity of calculation of the index from the connectivity in the molecular skeleton, together with the significant correlation, indicates its practical value. Good results have been obtained by using them to predict the half-wave potentials of some organic compounds.

STUDIES ON STRUCTURE-PROPERTY RELATIONSHIP BETWEEN COLOR REAGENTS AND SENSITIVITY OF THEIR COLOR-REACTIONS WITH YTTERBIUM BY TOPOLOGICAL INDEXES

In this paper A, topological indices and molecular connectivity inidces have been applied to multivariate analysis in structure-property studies. The topological indices of twenty asymmetrical phosphone bisazo derivatives of chromotropic acid have been calculated. The structure-property relationships between color reagents and molar absorptivity of color reactions with ytterbium have been studied by A(m) indices and molecular connectivity indices. Good results have been obtained.

THE EFFECTS OF LANTHANIDE IONS AND THEIR COMPLEXES ON THE PHASE-TRANSITION PROPERTY OF DIPALMITOYLPHOSPHATIDYLETHANOLAMINE LIPOSOMES

The effects of metal ions and lanthanide complexes on the gel-to-liquid crystal phase transition temperature T-m of dipalmitoylphosphatidylethanolamine liposomes have been studied by differential scanning calorimetry (DSC) method. The results show that the addition of metal ions to the dipalmitoylphosphatidylethanolamine (DPPE) liposomes dispersions increases the main phase transition temperature T-m in the order of monovalent< divalent< trivalent cations. The enhancement of T-m is not large as increasing the lanthanide ions concentration. The enhancement of Pr3+ is larger than that of La3+. Remarkable differences were observed between La-citrate and La-lactate complexes at different pH solutions. At pH 7.0, La-citrate complex has no effect on the T-m, La-lactate complex, however, increases the T-m value, and the increase is larger than that of free lanthanide ions at the same concentration. The decrease of pH of complexes solutions lowers the phase transition temperature. We have preliminarily discussed the mechanism of the enhancements of lanthanide ions and the synergism of lanthanide ion and lactate ligand follow the ion induced dehydration of lipid and the potential effects of ion-lipid interaction.

A STUDY OF THE CATALYTIC PROPERTIES OF PEROVSKITE-TYPE OXIDES LAMNYCO1-YO3 .2. THE INTERACTION BETWEEN TRANSITION-METAL IONS AND THEIR CATALYTIC PROPERTY IN AMMONIA OXIDATION

It has been found that the interaction between the two transition metal Mn, Co ions on B-site and their Redox property an the important factors influencing the NO-selectivity in ammonia oxidation. The NO-selectivity is related to the redox ability of Mn3+

INFLUENCE OF THE SUBSTITUTION OF Y BY IN ON THE STRUCTURE AND MAGNETIC PROPERTY OF Y2CU2O5

In2CuO5 is isostructural to Y2Cu2O5 both in its crystal and magnetic structure. In and Y can be substituted by each other in any ratio to make new compounds Y2-xInxCu2O5 (x = 0-2) which were identified by XRD and IR spectrum. The structural change in Y2-x