The kinetics of galactoside-proton symport catalysed by a wild-type strain and one carrying a mutation, previously reported to cause uncoupling of the symport reaction, have been examined. The mutation does not affect the stoichiometry during the initial period of uptake, when the internal concentration of galactoside is low, but it does result in much greater competition from the galactoside a...

Iron aluminide FeT2Alz8 was investigated in states with different defect concentrations using the positron annihilation lifetime and Mossbauer spectroscopy methods. The dominant component of 178-187 ps, obtained from positron lifetime spectra analysis, corresponds to a high density of vacancies. In the sample where high concentrations of vacancies or dislocations and vacancy clusters were found...

Wide-band-gap semiconductors typically can be doped either n type or p type, but not both. Compensation by native point defects has often been invoked as the source of this difficulty. We examine the wide-band-gap semiconductor ZnSe with first-principles total-energy calculations, using a mixed-basis program for an accurate description of the material. Formation energies are calculated for all ...

Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden-Popper (RP) oxides (A₂BO₄) are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen ...

Intensive investigations have been launched worldwide on the resistive switching (RS) phenomena in transition metal oxides due to both fascinating science and potential applications in next generation nonvolatile resistive random access memory (RRAM) devices. It is noteworthy that most of these oxides are strongly correlated electron systems, and their electronic properties are critically affec...

An indigenously developed chemical spray pyrolysis system was used to deposit polycrystalline CuInS2 thin films. It was found that smaller spray rate results in films with better crystallinity and lower resistivity. Increase in surface roughness of the films was observed for higher spray rates. Variations in film stoichiometry with composition of spray solution were analyzed along with its opto...

Solid-state reactions of elemental sulfur with metallic cobalt and molybdenum powders were used to synthesize model catalysts for hydrodesulfurization (HDS). The resulting materials had a general stoichiometry of CozlMo,-,S2 with x between 0.025 and 0.3. The solid phases formed during synthesis and after exposure to typical HDS reaction conditions were identified by X-ray diffraction and select...

in the crystal structure of the title polymeric compound, [c42h38n6o33sr5.2(h2o)]n, five independent metal atoms (sr1-sr5) have different coordination environments. the sr1 and sr5 atoms are nine coordinated and feature distorted tricapped trigonal-prismatic and capped square-antiprismatic geometries, respectively. the rest srii atoms have eight coordination numbers. these units are connected v...

Understanding the ecological consequences of evolutionary change is a central challenge in contemporary biology. We propose a framework based on the ˜25 elements represented in biology, which can serve as a conduit for a general exploration of poorly understood evolution-to-ecology links. In this framework, known as ecological stoichiometry, the quantity of elements in the inorganic realm is a ...

Introduction Conclusions References