/ Petroleum asphaltenes are defined as the n-pentane or n-heptane insoluble but toluene soluble fraction of crude oils or petroleum residua. This operational definition is a consequence of the extremely complex structure of asphaltenes which consist of thousands of compounds containing highly aromatic cores, long chain aliphatic groups, heteroatoms (sulfur, nitrogen, and oxygen) as well as trac...

Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three...

A large number of unexploited low-grade vanadium-titanium magnetite deposits have been found in the Chao-yang area of China in recent years. The reserves are estimated at more than 20 billion tons. A mineralogical study of raw sample indicated that it was a typical low-grade vanadium-titanium magnetite ore with weathering. Most of vanadium-titanium magnetite was replaced by martite and sphene, ...

Interest in vanadium chemistry has increased since the recognition of the involvement of vanadium ions in many important biological systems.1 The distinctive preference of the vanadium ion for N/O donor atom types has prompted the synthesis and characterization of many model complexes containing N/O donor ligands, the spectroscopic properties and solution behavior of which have been investigate...

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...

Extraction of reliable bond distances and angles for Ca10(VxP1-xO4)6F2 apatites using standard Rietveld refinement with Cu Kalpha X-ray powder data was significantly impaired by large imprecision for the O-atom coordinates. An initial attempt to apply crystal-chemical Rietveld refinements to the same compounds was partly successful, and exposed the problematic determination of two oxygen-metal-...

Polychlorinated benzenes, dibenzo-p-dioxins (PCDD), and dibenzofurans (PCDF) may be formed below the combustion temperature in fly ash from municipal solid waste incinerators (MSWI). Copper catalyzes this formation, possibly by the Deacon reaction. Many other elements are also Deacon catalysts or promoters, and here we report results from a statistically designed experiment with 15 metal oxides...

The chemistry section of the symposium will concentrate on. the chemistry qf vanadium that .has .possible relevance to vanadium b_ioche.mistry or therapeutic applications.. The biochemistry section will cover topics trom the essentiality of vanadlpm to vanadium-dependent haloperoxidases to vanadium bioactivity in cell cuItures. The therapeutic section will predominantly, address the insulin-mim...

Vanadium-niobium oxide catalysts containing variable amounts of vanadium and prepared by coprecipitation were investigated using 51V solid-state NMR. It was found that, in samples containing less than about 8 mol % V2O5, vanadium occurs in three different oxygen environments: in isolated tetrahedra, in comer-sharing tetrahedra (pyrovanadate), and in distorted octahedra. The number of octahedral...