Vanadium additions

The colour sequence already described, for the reduction of van-adium(V) to vanadium(II) by zinc and acid, gives a very characteristic test for vanadium. Addition of a few drops of hydrogen peroxide to a vanadate V) gives a red colour (formation of a peroxo-complex) (cf. titanium, which gives an orange-yellow colour). 

The Fe—Co alloys exist ia the fee stmeture above 912—986°C to ca 70 wt % Co. Below this temperature range, the stmeture changes to bcc. At ca 50 wt % Co, the material further orders to the CsCl-type B2 stmeture below about 730°C and becomes very brittle. The addition of V ia Permeadur retards the rate of orderiag and imparts substantial ductiHty to the adoy, although quenching is necessary. Vanadium addition also iacreases the resistivity, eg, from 7—26 fifl-cm usiag a 2% addition. 

Carbon Reduction. The production of ferrovanadium by reduction of vanadium concentrates with carbon has been supplanted by other methods. An important development has been the use of vanadium carbide as a replacement for ferrovanadium as the vanadium additive in steelmaking. A... 

C-M bond addition, for C-C bond formation, 10, 403-491 iridium additions, 10, 456 nickel additions, 10, 463 niobium additions, 10, 427 osmium additions, 10, 445 palladium additions, 10, 468 rhodium additions, 10, 455 ruthenium additions, 10, 444 Sc and Y additions, 10, 405 tantalum additions, 10, 429 titanium additions, 10, 421 vanadium additions, 10, 426 zirconium additions, 10, 424 Carbon-oxygen bond formation via alkyne hydration, 10, 678 for aryl and alkenyl ethers, 10, 650 via cobalt-mediated propargylic etherification, 10, 665 Cu-mediated, with borons, 9, 219 cycloetherification, 10, 673 etherification, 10, 669, 10, 685 via hydro- and alkylative alkoxylation, 10, 683 via inter- andd intramolecular hydroalkoxylation, 10, 672 via metal vinylidenes, 10, 676 via SnI and S Z processes, 10, 684 via transition metal rc-arene complexes, 10, 685 via transition metal-mediated etherification, overview,... 

Vanadate stimulates protein kinases in the cytosol, as demonstrated in adipose cells and extracts. The activation of a membrane and cytosolic protein tyrosine kinase have been demonstrated in adipocytes, and the membranous enzyme has been postulated to be a way to involve PI-3K actions without activation of insulin receptor substrate-1 (IRS-1) in the insulin signal transduction pathway [140], It is always difficult to determine if protein kinase activation is direct or the result of stimulation of a protein phosphatase. The fact that kinase stimulation was seen in isolated extracts after cell disintegration in this adipocyte cell system supports the idea that vanadium addition to cells could directly stimulate kinases via an as-yet-undetermined mechanism. In other experiments with 3T3-L1 adipocytes bis(acetylacetonato)oxovana-dium (IV) BMOV and bis(l-N-oxide-pyridine-2thiolato)oxovanadium (TV) caused increased tyrosine phosphorylation of both the insulin receptor and IRS-1 in a synergistic way with insulin, as measured by antibodies to phosphotyrosine residues [141]. 

It is shown that the addition of vanadium led to a slight enhancement in the selectivity to MAA, both at 260C and at total IBA conversion, with respect to the Ki sample the formation of acetone and propylene decreased, while that of COx increas. However, the improvement in performance obtained by vanadium addition was low, if compared to that reported in literature for vanadium-modified heteropolycompoimds. 

At low temperature (Table 2), deactivation is not observe for D-USY catalyst and the selectivity for methylcyclopentane increases when compared to high temperature results. The quantity of benzene also increase. The 1-Ni catalyst presents a decrease of the activity of 50%. For 1 V catalyst this behavior is more severe and the decrease activity is around 94%. With nickel and vanadium addition (lNi-3V catalyst) the decrease in the activity is approximately85%. 1-V catalyst did not present dehydrogenation properties at low temperature reaction. 

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