David Virgo

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The kinetics of the Fe(2+)-Mg, order-disorder phenomenon in a highly ordered natural anthophyllite have been determined over the temperature range from 400 degrees to 720 degrees C at a pressure of 2 kilobars. At temperatures of 600 degrees C and above, equilibrium is attained by disordering as well as ordering reactions. The intracrystalline exchange is(More)
In view of the lack of information regarding careers for toxicologists in Europe, the Individual Members of EUROTOX organised a workshop on careers in toxicology during the EUROTOX Congress 2000 in London. Toxicologists are mainly employed in academia, regulatory agencies, contract research organisations (CROs) and the chemical and pharmaceutical(More)
A structural model is proposed for the polymeric units in silicate melts quenched at 1 atmosphere. The anionic units that have been identified by the use of Raman spectroscopy are SiO(4)(4-) monomers, Si(2)O(7)(6-) dimers, SiO(3)(2-) chains or rings, Si(2)O(5)(2-) sheets, and SiO(2) three-dimensional units. The coexisting anionic species are related to(More)
In view of the lack of information regarding careers for toxicologists in Europe, the Individual Members of EUROTOX organised a workshop on careers in toxicology during the EUROTOX Congress 2000 in London. Toxicologists are mainly employed in academia, regulatory agencies, contract research organisations (CROs) and the chemical and pharmaceutical(More)
The toxicity of glucagon produced by recombinant DNA technology (Glucagon (ge)) was studied by daily intravenous administration to rats and dogs for 4 weeks. Pancreatic glucagon of bovine or porcine origin (Glucagon Novo) was used as a reference control in the dogs. Glucagon (ge) has the same sequence of the 29 amino acids as pancreatic glucagon of humans,(More)
Site occupancy numbers for ferrous iron, magnesium, and calcium at the Ml and M2 sites in lunar clinopyroxenes are estimated from nuclear gamma-ray resonant absorption spectra of (57)Fe. The cation distribution is ordered; calcium and magnesium prefer M2 and Ml, respectively. The distribution corresponds to an equilibrium at a temperature lower than 680(More)
Carbon dioxide has attracted the attention of igneous petrologists because of its influence on phase equilibria relevant to partial melting in the upper mantle (ag., Yoder, 1973; Eggler, 1973,1975, 1978; Eggler and Rosenhauer, 1978; Huang and Wyllie, 1976; Wendlandt and Mysen, 1978; Mysen and Boettcher, l975a,b). Some of these authors have shown that the(More)
The viscosity-temperature relationships of nine melts in the NazO-FeO-Fe20&iO~ system (in equilibrium with air) have been measured in the temperature range of 145&800”C, using the concentric cylinder method. “Fe Miissbauer spectra were obtained on quenched samples and show that all melts with 220 mole% ferrite component contain ~95% Fe as(More)
Triethylenetetramine dihydrochloride (trientine-2HCl, TJA-250), a copper chelating agent used to treat Wilson's disease, was administered orally to male and female F-344 rats for 4 or 8 weeks at dosages of 0, 100, 350 or 1200 mg/kg/day or for 26 weeks at dosages of 50, 175 or 600 mg/kg/day. 4 or 8-week study. Two males receiving 1200 mg/kg/day died during(More)
Order-disorder transitions between ferrous iron and magnesium in orthopyroxenes [minerals close to the composition (Fe, Mg) SiO(3)] occur rapidly between approximately 480 degrees and 1000 degrees C. Disordering and ordering have been studied experimentally. The determination of the metastable ferrous iron site occupancy in orthopyroxenes from rapidly(More)