Feasibility of producing high purity silicon from amorphous silica fume, using a low temperature magnesiothermic reduction was demonstrated. Commercial silica fume containing 97.5% amorphous silica was first purified by acid leaching and roasting to remove large quantities of transition metals and carbon. The product was then reduced using magnesium as the reductant. The effect of the amount of reductant, initial temperature, and dwell time were investigated on the quantity and type of the reaction products. The optimum reduction conditions were decided based on the maximum yield of the Si metal. These corresponded to Mg/SiO 2 molar ratio of 2.0, preheating temperature of 750°C, and holding time of 2 h. High purity silicon (N 99 wt.%) containing b 3 ppmw B and 12 ppmw P was obtained after leaching purification of the reduction products, showing that the material is superior to metallurgical grade silicon, for use as solargrade silicon feedstock.

The 30-day survival after exposure to 800 Rad 60Co gamma radiation has been compared for female mice maintained on vitamin E deficient, vitamin E supplemented or regular lab rations before and/or after irradiation. Pre- or post-irradiation dietary supplementation had no effect on survival; however, injection of alpha-tocopherol immediately after irradiation significantly reduced radiation lethality.

The effect of alpha-tocopherol on in vitro proliferation of murine splenic lymphocyte cultures supplemented with various concentrations of the vitamin has been measured at sub-optimal, optimal and supra-optimal levels of the T-cell mitogen Concanavalin A (Con A). In the concentration range (1-25 micrograms/ml), tocopherol enhanced proliferation when administered up to 24 hours after exposure to sub-optimal and optimal concentrations of Con A; however, at supra-optimal levels of the mitogen, it appeared to inhibit proliferation. In the concentration range 50-100 micrograms/ml, tocopherol supplementation only enhanced proliferation in response to sub-optimal concentration of Con A. The spontaneous proliferation of lymphocytes in the absence of mitogens was increased by tocopherol supplementation at all concentrations tested. In contrast, there appeared to be only slight stimulation of B-cell proliferation in response to optimal concentration of bacterial lipopolysaccharide (LPS) by lower levels of vitamin E. Tocopherol supplementation of cultures over a broad range of concentrations (0.5-100 micrograms/ml) had no significant effect on cell viability before onset of proliferation at 18 hours after exposure to Con A, nor was there evidence of earlier onset of DNA synthesis in response to mitogen in the presence of 5 micrograms/ml of the vitamin. Although macrophage depletion of cultures impaired proliferation induced by Con A, tocopherol supplementation continued to stimulate proliferation at optimal and sub-optimal levels of mitogen.

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