Copper(II) oxalate obtained through the reaction of 1,2-ethanediol with Cu(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>·3H<Subscript>2</Subscript>O

The paper presents the experimental results of the structural investigations and thermal analysis of copper(II) oxalate, a polynuclear coordination compound, obtained by a new method, through the reaction of 1,2-ethanediol with Cu(NO₃)₂·3H₂O. The reaction between 1,2-ethanediol and Cu(NO₃)₂·3H₂O occurs, under some working conditions, with the oxidation of 1,2-ethanediol to the oxalate anion (L). The synthesized polynuclear coordination compound, [CuL·0.3H₂O]_n, was characterized by chemical analysis, electronic and vibrational spectra and thermal analysis. The thermal properties of the polynuclear coordination compound have been investigated by TG, DTG and DSC. The obtained decomposition product is CuO. Powder XRD (X-ray diffraction), IR spectroscopy and TEM (transmission electron microscopy) were used to characterize the composition, the crystalline structure and the surface morphology of the copper oxide obtained through thermolysis. The thermal conversion product, copper(II) oxide, has a microporous structure with a large specific area.     

Separating the contribution of translational and rotational diffusion to protein association

The association of two proteins is preceded by a mutual diffusional search in solution. The role of translational and rotational diffusion in this process has been studied theoretically for many years. However, systematic experimental verification of theoretical results is still lacking. We report here measurements of association rates of the proteins beta-lactamase (TEM) and beta-lactamase inhibitor protein (BLIP) in solutions of glycerol and poly(ethylene glycol) of increasing viscosity. We also measured translational and rotational diffusion in the same solutions, using fluorescence correlation spectroscopy and fluorescence anisotropy, respectively. It is found that in glycerol both translational and rotational diffusion rates are inversely dependent on viscosity, as predicted by the classical Stokes-Einstein relations, while the association rate depends nonlinearly on viscosity. In contrast, the association rate depends only weakly on the viscosity of the polymer solutions, which results in a similar weak dependence of k(on) on viscosity. The data are modeled using the theory of diffusion-limited association. Deviations from the theory are explained by a short-range solute-induced repulsion between the proteins in glycerol solution and an attractive depletion interaction generated by the polymers. These results open the way to the creation of a unified framework for all nonspecific effects involved in the protein association process, as well as to better theoretical understanding of these effects. Further, they reflect on the complex factors controlling protein association within the crowded environment of cells and suggest that a high concentration of macromolecules does not significantly impede protein association.     

Yield of singlet excitons in organic light-emitting devices: a double modulation photoluminescence-detected magnetic resonance study

Double-modulation (DM) photoluminescence (PL) detected magnetic resonance (PLDMR) measurements on poly(2-methoxy-5-(2(')-ethyl)-hexoxy-1,4-phenylene vinylene) are described. In these measurements, the laser excitation power is modulated at 1相似文献   

Anticipated utility: A measure representation approach

This paper presents axioms which imply that a preference relation over lotteries can be represented by a measure of the area above the distribution function of each lottery. A special case of this family is the anticipated utility functional. One additional axiom implies this theory. This functional is then extended for the case of vectorial prizes.The author is grateful to Chew Soo Hong, Larry Epstein, Joe Ostroy, Joel Sobel, Peter Wakker, and Menahem Yaari for their comments.     

Kinetic analysis of sequence of two consecutive reactions from thermogravimetric data under non-isothermal conditions. I. Calculated thermograms

This paper suggests a method of drawing the thermogram of a sequence of two consecutive, partially overlapping processes of a given order, run under non-isothermal conditions.     

Reduced mono-, di-, and tetracubane-type clusters containing the [MoFe3S4]2+ core stabilized by tertiary phosphine ligation

Treatment of oxidized clusters [(Cl4cat)(MeCN)MoFe3S4Cl3]2- (1) and [(Meida)MoFe3S4Cl3]2- (2) with tertiary phosphines in the presence of NaBPh4 in acetonitrile results in chloride substitution at the iron sites and the formation of clusters with the reduced [MoFe3S4]2+ core. Thus, 1 is a precursor to [(Cl4cat)(MeCN)MoFe3S4(PR3)3] (R = But (3), Pri (4)) and [(Cl4cat)2(Et3P)2Mo2Fe6S8(PEt3)4] (5). Cluster 2 affords [[(Meida)MoFe3S4(PCy3)3]4Fe2(mu-Cl)L2]3+ (L = THF (6), MeCN (7)). The structures of 3-7 were established by X-ray analysis. Clusters 3 and 4 are single cubanes, centrosymmetric 5 (previously reported in a different space group: Demadis, K. D.; Campana, C. F.; Coucouvanis, D. J. Am. Chem. Soc. 1995, 117, 7832) is a double cubane with a rhomboidal Fe2S2 bridge, and 6 and 7 are tetracubanes. In the latter, four Meida oxygen atoms from different cubanes bind each of two central high-spin Fe(II) atoms in trans-Fe(mu-Cl)LO4 coordination. The topology of these clusters is not precedented. Zero-field M?ssbauer parameters for all clusters are reported. Isomer shift considerations suggest the formulation [Mo3+Fe2+2Fe3+S4] for reduced clusters. Voltammetry of 3 and 4 reveals four-member electron transfer series encompassing the oxidation levels [MoFe3S4]4+,3+,2+,+ in the potential interval + 1.0 to -1.3 V vs SCE in dichloromethane. Compared to the clusters with monoanionic ligands at the iron sites, phosphine ligation shifts redox potentials to more positive values. This effect arises from reduction of cluster negative charge and the tendency of phosphines to stabilize lower oxidation states. The synthesis of reduced clusters 4 from 1 and of [Fe4S4(PPri3)4]+ from [Fe4S4Cl4]2- is accompanied by the formation of Pri3PS, detected by 31P NMR, indicating that the phosphine is the reductant. This result implies a similar function of tertiary phosphines in the synthesis of 3 and 5-7. (Cl4cat = tetrachlorocatecholate(2-); Meida = N-methyliminodiacetate(2-).)     

Polymerization of anilinium–DBSA in the presence of clay particles: kinetics and formation of core‐shell structures

This paper is an extension of previous work on polymerization of anilinium–DBSA (dodecylbenzenesulfonic acid) in an aqueous dispersion in the presence of mica or talc silicate particles. The presence of mica or talc particles greatly accelerates the polymerization process of anilinium‐DBSA and an encapsulated structure is formed as well. The catalytic effect of various metallic cations which exist in the chemical compositions of mica or talc on the polymerization kinetics of anilinium‐DBSA was investigated. The conductivity results along with microscopy observations prove a well formed encapsulated structure for the polyaniline/mica composites, but less for the polyaniline/talc composites. The anilinium‐DBSA complex and mica aqueous dispersions pretreated at different temperatures prior to polymerization have shown a significant effect on the polymerization rate of anilinium‐DBSA. The higher the dispersion temperature, the higher is the polymerization rate found. Copyright © 2001 John Wiley & Sons, Ltd.