نتایج جستجو برای: vanadium v oxide
تعداد نتایج: 478824 فیلتر نتایج به سال:
The aims of this study were to clarify the effects of high vanadium on the renal cell cycle and apoptosis in broilers. 420 one-day-old avian broilers were divided into six groups and fed on a control diet (vanadium 0.073 mg/kg), and five high vanadium diets (vanadium 5 mg/kg, high vanadium group I; 15 mg/kg, high vanadium group II; 30 mg/kg, high vanadium group III; 45 mg/kg, high vanadium grou...
The unusual ascidian ability to accumulate high levels of vanadium ions at concentrations of up to 350 mM, a 10(7)-fold increase over that found in seawater, has been attracting interdisciplinary attention for a century. Accumulated V(V) is finally reduced to V(III) via V(IV) in ascidian vanadocytes. Reducing agents must therefore participate in the reduction. Previously, we identified a vanadi...
The title potassium vanadium tungsten bis-(arsenate oxide) was synthesized by a solid-state reaction at 973 K. The crystal structure is isotypic with KVOPO(4) and contains a [MVAs(2)O(10)](∞) framework built up from single MO(6) (M = V+W) octa-hedra sharing corners with single VO(6) octa-hedra and AsO(4) tetra-hedra. This structure shows the existence of infinite [VAsO(8)](∞) and [MAsO(8)](∞) c...
Density functional theory was used to study the mechanism for the oxidation of methanol to formaldehyde. A vanadium oxide cluster O=V(OH)(3) has been utilized to represent the catalytic system under hydrated conditions, i.e., in the presence of V-OH hydroxyl groups. Two types of methoxy-intermediates have been considered: a penta-coordinate methoxy-intermediate (OH)(4)V(OCH(3)) and a tetrahedra...
Abstract: (Y2O3) and ethyl acetate as a mineralizer by hydrothermal method at a low temperature (T=.230°C, andP=100bars).The as-prepared powders were characterized by X-ray Diffraction (XRD), Fourier Transform InfraredSpectroscopy (FTIR), Scanning Electron Microscopy (SEM), UV-V Spectroscopy and Chemical Oxygen Demand(COD) of the sewage water, respectively. The results show that hydrothermal me...
The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and charact...
We report here the Raman spectrum and lattice dynamics study of a well-crystallized β-V(2)O(5) material prepared via a high-temperature/high-pressure (HT/HP) route, using α-V(2)O(5) as the precursor. Periodic quantum-chemical density functional theory calculations show good agreement with the experimental results and allow one to assign the observed spectral features to specific vibrational mod...
The bulk structural evolution of a vanadium containing heteropolyoxomolybdate (HPOM), H4[PVMo11O40] * 13 H2O, with vanadium substituting for Mo in the Keggin ion was studied under reducing (propene) and partial oxidation reaction conditions (propene and oxygen) by in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) combined with mass spectrometry. During treatment in propene...
A simple and sensitive extractive- spectrophotometric method for thedeterrnination of trace amounts of vanadium(V) is reported. The method is based on the quantitative extraction of the anion complex of V(V) with 4-(2-pyridy1azo)-resorcinol with tetrabutylammonium perchlorate into chloroform, followed by spectrophotometric measurements at 554 nm. Beer's law is obeyed over the concentration ...
Chromium-vanadium (Cr-V) bimetallic catalysts are prepared by the introduction of vanadium into the Phillips catalyst which is one of the most significant industrial ethylene polymerization catalysts for tuning the Phillips catalyst performances and improving polyethylene properties. In the present work, titanium species were introduced into the fluorine-modified chromium-vanadium bimetallic ca...
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