Tungsten oxide nanoclusters supported highly ordered mesoporous SBA-15 material has been successfully synthesized in a single step using a non-ionic surfactant as a template and used for the selective oxidation of sulfur compounds, giving excellent yields at room temperature with exceptional catalyst recyclability.

In order to limit the dispersive use of lead on small arms firing ranges, 5.56-mm bullets with tungsten-nylon composite material cores have been fired at a number of Army training ranges. Tungsten in bullet residues oxidizes when exposed to the atmosphere, yielding an amorphous tungsten oxide (WO3) coating. This coating rapidly dissolves to yield the tungstate anion (WO4), which can migrate in ...

The Report on Carcinogens includes two separate listings (i.e., profiles) for cobalt-related exposures: Cobalt and Cobalt Compounds That Release Cobalt Ions In Vivo and Cobalt-Tungsten Carbide: Powders and Hard Metals. Cobalt and cobalt compounds as a class are listed for the first time in the Fourteenth Report on Carcinogens, and this listing includes and supersedes the listing for cobalt sulf...

The tungsten-182 Mössbauer spectra of a series of Keggin structure heteropolytungstates, [EW12O40]n- are reported. There is a very considerable variation in quadrupole coupling at the tungsten nucleus indicating considerable asymmetry in the electron distribution for the more electronegative elements E. The quadrupole coupling correlates well with the structural data, in particular with the dis...

The reaction of the 1,2-dihalodiborane(4) B2(NMe2)2Cl2 with the lithium tungsten salts Li[(η5C5H5)(R3P)(OC)2W] [R = Me (3a), Ph (3b)] yields via alkali salt elimination the phosphinesubstituted diborane(4)yl tungsten complexes [(η-C5H5)(R3P)(OC)2W-{B(NMe2)-B(NMe2)Cl}] [R = Me (4a), Ph (4b)]. Both compounds have been fully characterized in solution by NMR and IR spectroscopy and 4a additionally ...

OBJECTIVES To assess the exposure to tungsten, cobalt, and nickel in a plant producing hard metals. The main components of hard metals are tungsten carbide and cobalt metal. According to recent studies, these two components may be responsible for both fibrogenic and carcinogenic effects. METHODS 87 workers were investigated (86 male, one female) with a median age of 42 (range 22-58) and a mea...

Using density functional theory calculations, many researchers have predicted that various tungsten nitride compounds N1−xWx (x < 12 ) will be “ultraincompressible” or “superhard,” i.e., as hard as or harder than diamond. Necessary conditions for such compounds are that they have large bulk and shear moduli, greater than approximately 200 GPa, and are elastically and vibrationally stable. Compo...

Electropolishing of metals often leads to supersaturation conditions resulting in precipitation of complex compounds. The solubility diagrams and Gibbs adsorption isotherms of the electropolishing products are thus very important to understand the thermodynamic mechanism of precipitation of reaction products. Electropolishing of tungsten wires in aqueous solutions of potassium hydroxide is used...

A chemistry-based approach to designing precursors for the deposition of inorganic films requires consideration of the physical properties of the precursor compound (e.g., volatility for transport in the reactor) and its probable decomposition pathways, both in the gas phase and on the surface during growth. We have been using Aerosol-Assisted Chemical Vapor Deposition of tungsten carbonitride ...