Vanadium K-edge X-ray-absorption spectra were collected for samples of thionine-oxidized, super-reduced (during enzyme turnover) and dithionite-reduced VFe-protein of the vanadium nitrogenase of Azotobacter chroococcum (Acl*). Both the e.x.a.f.s and the x.a.n.e.s. (X-ray-absorption near-edge structure) are consistent with the vanadium being present as part of a VFeS cluster; the environment of ...

Ž . The environmental impact of both the vanadium redox battery vanadium battery and the lead-acid battery for use in stationary applications has been evaluated using a life cycle assessment approach. In this study, the calculated environmental impact was lower for the vanadium battery than for the lead-acid one. The net energy storage efficiency of the vanadium battery was greater due to lower...

Solid-phase spectrophotometry has been applied to analysis for trace amounts of vanadium. Vanadium was sorbed in a styrene-divinylbenzene-type anion-exchanger Dowex 1-X8 as a vanadium-4-(2-pyridylazo)resorcinol complex. Resin phase absorbances at 562 and 800 nm were measured directly which allowed the determination of vanadium in the range of 0.1-2.4 ng/ml with a RSD of 1.5%. The method has bee...

Biochemical and haematological profiles of workers exposed to vanadium were compared with those of non-exposed age matched subjects. A significantly positive and dose related correlation between serum vanadium and zinc protoporphyrin (ZPP) was observed. Normal lead concentrations excluded this heavy metal as a possible cause. Inhibition of the reduction of Fe to Fe++ by vanadium is discussed as...

A complete package [ensemble, complex] of physical and chemical investigations was conducted: x-ray phase analysis, differential thermal analysis waste generated in the production vanadium. It established that these wastes, which contain 17.39% Mn2O3 their composition, are a promising raw material for wall ceramics with volumetric-staiing. The effect heat treatment at 200, 500, 600, 700°C on co...

Vanadium nitride (VN) electrode displays high-rate, pseudocapacitive responses in aqueous electrolytes, however, it remains largely unclear nonaqueous, Na+-based electrolytes. The traditional view supposes a conversion-type mechanism for Na+ storage VN anodes but does not explain the phenomena of their size-dependent specific capacities and underlying causes charge behaviors. Herein, we insight...

Lithium-based conducting glasses are promising candidates for electrolyte materials of thin-film batteries because they exhibit isotropic ionic conductivity. However, at room temperature most of such conducting glasses exhibit relatively low ionic conductivity values, in the range 10 to 10 S/m. In order to increase the conductivity, some specific additives have been used, one of them being vana...

The influence of the vanadium load and calcination temperature on the structural characteristics of the V2O5/TiO2 system was studied by X-ray diffraction and X-ray absorption spectroscopy (XAS) techniques. Samples of the V2O5/TiO2 system were prepared by the sol–gel method under acid conditions and calcined at different temperatures. The rutile phase was found to predominate in pure TiO2 calcin...

Since Henze discovered vanadium in the blood (or coelomic) cells of an ascidian in 1911, this unusual phenomenon has attracted the interest of many investigators. The highest concentration of vanadium (350 mM) in the blood cells of Ascidia gemmata, which belongs to the suborder Phlebobranchia, is 10(7) times higher than that in seawater. Of the approximately 10 types of blood cells, a combinati...

This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the s...