Ion Mobility,Phase Transitions,and Ion Conductivity in Alkali Metal Tetrafluoroantimonates(III) MSbF4 (M = Na,K, Rb,Cs)

The internal mobility of fluoride ions and electrophysical characteristics of alkali metal tetrafluoroantimonates(III) (M = Na, K, Rb, and Cs) are studied by ¹⁹F NMR and impedance spectroscopies. The types of ion motions in the anionic sublattice of these compounds are determined in the 180-510 K temperature range. The superionic conductivity of the MSbF₄ compounds is established above 480 K ( 2.9 × 10^-2 to 1.3 × 10^-4 S/cm).     

The enthalpies of formation of copper(II) complexes with nicotinamide in aqueous ethanol and DMSO

The enthalpies of complex formation between nicotinamide and copper(II) perchlorate in aqueous ethanol and dimethylsulfoxide (DMSO) were determined calorimetrically. The maximum exothermic effect was observed in a solvent with ～0.1 mole fractions of DMSO. The exothermic effect of complex formation increased as the concentration of ethanol grew. The role played by solvation in the thermodynamic characteristics of monoligand complex formation was considered. The influence of solvent composition on Δ_r H ^o was largely related to the resolvation of the ligand donor atom.     

Quantitative analysis of relative protein contents by Western blotting: comparison of three members of the dystrophin-glycoprotein complex in slow and fast rat skeletal muscle

We have developed a method for accurate quantitative analysis and statistical comparison of the relative contents of the dystrophin-glycoprotein complex (DGC) in skeletal muscle. This method was applied to compare DGC contents in slow (soleus) and in fast (extensor digitorum longus, EDL) rat skeletal muscles. The quantitative analysis combines a modified bicinchoninic acid (BCA) assay with Western blotting and enhanced chemiluminescence (ECL). This combination allows the use of high levels of detergents and reducing reagents essential for extracting DGC. In addition, the evaluation of the total amount of proteins in each sample makes it possible to have a reference and to accurately compare relative protein levels without using a specific standard. With a large gradient gel, we could concomitantly compare two groups (n = 9) and quantify all protein contents differing highly in their molecular masses (from 35 kDa to 427 kDa). Each experiment was triplicated and normalized; the two muscles were compared using the Mann-Whitney test (P<0.001) to establish their protein content. The DGC relative levels for the slow muscle soleus and the fast muscle EDL differed significantly: dystrophin, beta-dystroglycan, and gamma-sarcoglycan levels were 130%, 110% and 120% higher in the soleus, respectively. The differences observed in the expression level of cytoskeletal associated protein (dystrophin) and transmembranous anchorage components may correspond to a physiological response of the muscle fibers to duration, magnitude, and frequency of the imposed mechanical loading.     

Radiation-induced conductivity in poly(phenylene vinylene) derivatives

Using the pulse-radiolysis time-resolved microwave conductivity technique the mobility and decay kinetics of radiation-induced charge carriers is studied in a series of poly(2,5-dialkoxy-phenylene vinylene) derivatives. The lower limit to the sum of the mobilities of the positive and negative charge carriers, Σμ_min, depends strongly on the alkoxy functionalization and ranges from 1.2·10⁻⁷ to 1.4·10⁻⁶ m²/V·s at room temperature. Σμ_min increases with the degree of order in the material. The after-pulse conductivity decay kinetics are disperse and are controlled by a combination of charge recombination and trapping.     

The effect of gamma-irradiation of anthracite coal and oil bitumen

Anthracite coal and oil bitumen were submitted to γ-radiation at a total dose of 1 MGy and the radiation-processed samples were studied by FT-IR spectroscopy, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The coal samples were studied also by TGA coupled with FT-IR spectroscopy of the evolved gases. Thermal analysis has revealed a completely different behavior of the radiolyzed samples in comparison to the unirradiated samples. Both for coal and bitumen significantly less volatile fraction was released during the TGA and in both cases a significant increase in the amount of carbon coke produced at 800-900 °C was observed. The radiation processed bitumen increased significantly its ethyl acetate insolubles content. These results were interpreted in terms of extensive crosslinking and coalification of the samples under the action of γ-radiation. The results of this study have been applied to the carbonization process of terrestrial sedimentary organic matter which is commonly attributed to the action of heat flux from the depth of the Earth but which may be also due to the action of natural radiation. Other application of the results of the present study is to the complex organic matter present on the surfaces of comets and meteorites. This complex matter was formed by exposure of simple precursors to a field of high energy radiation for millions or billions of years and is consequently transformed into coal-like and bitumen-like matter. The same arguments apply to the carbon grains present in the interstellar and circumstellar medium. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solution chemistry of uranyl ion with iminodiacetate and oxydiacetate: A combined NMR/EXAFS and potentiometry/calorimetry study

The solution chemistry of uranyl ion with iminodiacetate (IDA) and oxydiacetate (ODA) was investigated using NMR and EXAFS spectroscopies, potentiometry, and calorimetry. From the NMR and EXAFS data and depending on stoichiometry and pH, three types of metal:ligand complex were identified in solution in the pH range 3-7: 1:1 and 1:2 monomers; a 2:2 dimer. From NMR and EXAFS data for the IDA system and previous studies, we propose the three complex types are [UO(2)(IDA)(H(2)O)(2)], [UO(2)(IDA)(2)](2)(-), and [(UO(2))(2)(IDA)(2)(mu-OH)(2)](2)(-). From EXAFS spectroscopy, similar 1:1, 2:2, and 1:2 complexes are found for the ODA system, although (13)C NMR spectroscopy was not a useful probe in this system. For the 1:1 and 1:2 complexes in solution, EXAFS spectroscopy is ambiguous because the data can be fitted with either a long U-N/O(ether) value (ca. 2.9 A) suggesting 1,7-coordination of the ligand or a U-C interaction at a similar distance, consistent with terminal bidentate coordination. However, the NMR data of the IDA system suggest that 1,7-coordination is the more likely. The stability constants of the three complexes were determined by potentiometric titrations; the log beta values are 9.90 +/-, 16.42 +/-, and 10.80 +/- for the 1:1, 1:2, and 2:2 uranyl-IDA complexes, respectively, and 5.77 +/-, 7.84 +/-, and 4.29 +/- for the 1:1, 1:2, and 2:2 uranyl-ODA complexes, respectively. The thermodynamic constants for the complexes were calculated from calorimetric titrations; the enthalpy changes (kJ mol(-)(1)) and entropy changes (J K(-)(1) mol(-)(1)) of complexation for the 1:1, 1:2, and 2:2 complexes respectively are the following. IDA: 12 +/- 2, 230 +/- 8; 8 +/- 2, 151 +/- 9; -33 +/- 3, -283 +/- 11. ODA: 26 +/- 2, 198 +/- 12; 20 +/- 2, 106 +/- 8; -24 +/- 2; -219 +/- 8.     

Voltammetry of copper species in estuarine waters: Part I. Electrochemistry of copper species in chloride media

Theoretical and experimental voltammetric studies of copper reduction in chloride media show that electrodeposition on the hanging mercury drop electrode (HMDE) is controlled by competitive reduction between Cu(II) organic species and the Cu(I)Cl₂^? intermediate. For reversible Cu(II) species reduction, the change from organic ligand to chloride control of the final reduction step can be predicted by thermodynamic calculation. On the other hand in irreversible systems (e.g. estuarine waters) involvement of the CuCl₂^? intermedite in the electrodeposition is more complex and can occur both before and after amalgamation.     

Second-order relativistic electron capture

Starting with the impulse approximation, we analyse second-order effects in relativistic electron capture. The relation of this model with relativistic distorted-wave approximations is clarified. In particular it is shown that the second-order spin-coupling terms in the RCDW theory are consistent with the correct form given by perturbation theory. In the semirelativistic limit, the RCDW results are shown to accord with the formulae of Moiseiwitsch for flip and nonflip transitions in the ultra-relativistic limit. This confirms that the continuum-distorted-wave model generalises to relativistic spinors, and highlights the defects of scalar models. We also present a new symmetric eikonal theory which gives reliable results for capture without change of spin, but leads to a divergent total cross section for spin-flip transitions in the second-order term. This effect, which is quite distinct from the spurious spin-flip amplitudes of the scalar symmetric eikonal theory, is taken as further evidence that the eikonal approximation is not valid for magnetic transitions.     

New method for the synthesis of sym- octahydroxanthenes and sym- octahydrothioxanthenes

-Ketols formed as a result of intramolecular cyclization of 1,5-diketones by alkaline condensation of aldehydes with ketones are converted to 9-R-sym-octahydroxanthenes by the action of acids. Treatment of the -ketols with acids in the presence of hydrogen sulfide leads to the corresponding 9-R-sym-octahydrothioxanthenes. The spectral characteristics of the compounds obtained are given, and some of their properties are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1615–1619, December, 1978.