Autocatalytic reactions may propagate as solitary waves, namely, at a constant front velocity and with a stationary concentration profile, resulting from a balance between molecular diffusion and chemical reaction. When the reaction is exothermic, a thermal wave is linked to the chemical front. As the thermal diffusivity is nearly two orders of magnitude larger than the molecular one, the tempe...

Chlorite dismutase (CD) catalyzes the disproportionation of chlorite to chloride (ClO(2)(-)-->Cl(-)+O(2)) and is present in bacteria capable of cell respiration using perchlorate or chlorate. The activity of this enzyme has previously been measured by monitoring oxygen evolution using a Clark-type dissolved oxygen (DO) probe. We demonstrate here, using two other methods to measure CD activity (...

OBJECTIVE To assess the safety and efficacy of a chlorine dioxide water treatment system in controlling Legionella in a hospital water supply. DESIGN For 17 months following installation of the system, we performed regular water cultures throughout the building, assessed chlorine dioxide and chlorite levels, and monitored metal corrosion. RESULTS Sites that grew Legionella species decreased...

The NrtA and NrtB nitrate transporters are paralogous members of the major facilitator superfamily in Aspergillus nidulans. The availability of loss-of-function mutations allowed individual investigation of the specificity and inhibitor sensitivity of both NrtA and NrtB. In this study, growth response tests were carried out at a growth-limiting concentration of nitrate (1 mM) as the sole nitrog...

In the reaction between equimolar amounts of horseradish peroxidase and chlorite, the native enzyme is oxidized directly to Compound II (Hewson, W.D., and Hager, L.P. (1979) J. Biol. Chem. 254, 3175-3181). At acidic pH but not at alkaline values, this initial reaction is followed by oxidation of Compound II to Compound I. The highly pH-dependent chemistry of Compound II can be readily demonstra...

The chlorite-tetrathionate reaction has been studied spectrophotometrically in the pH range of 4.65-5.35 at T = 25.0 +/- 0.2 degrees C with an ionic strength of 0.5 M, adjusted with sodium acetate as a buffer component. The reaction is unique in that it demonstrates autocatalysis with respect to the hydrogen and chloride ion products and the key intermediate, HOCl. The thermodynamically most-fa...

Introduction: The Bosumtwi Impact Crater in Ghana, Africa (6°32’N, 1°25’W) is a large complex crater. The crater is 10.5 km in diameter, with a central uplift 2 km in diameter. It is the source of the Ivory Coast Tektite field, found to the southwest of the crater over 200 km away. This study investigates the mineralogy, the petrology, and the geochemistry of drill core samples taken near the c...