The mechanism of enteroviral inactivation by ozone was investigated with poliovirus 1 (Mahoney) as the model virus. Ozone was observed to alter two of the four polypeptide chains present in the viral protein coat of poliovirus 1. However, the alteration of the protein coat did not significantly impair virus adsorption or alter the integrity of the virus particle. Damage to the viral RNA after exposure to ozone was demonstrated by velocity sedimentation analysis. It was concluded that the damage to the viral nucleic acid is the major cause of poliovirus 1 inactivation by ozone.
NC>2]2• The last two values can be measured at any two reaction times of convenience. This method is similar to that proposed by Holmes et al.(6), except that the present initial [NÜ2]i measurement should be made at a slightly later time, after [N2O5] reaches a steady state. However, if there is sufficient NO present in the reactant mixture initially, [N02]i can be determined at t = 0; and only one measurement of NO2 concentration-i.e., [N02]2, is needed after the photolysis.A set of 11 rate constants, of which seven are taken from the literature and four were derived from this study, is listed in Table I. When these rate constants were used in the mechanism (1-11), the concentration-time profiles of all species in the system were computed by a numerical integration scheme. The computed results are in good agreement with all observed data (Figures 2-5). Thus, the kinetics and mechanism derived here adequately describe the photolysis of NO2 at ppm level either in N2 or in air.
Three different enriched mixed cultures capable of degrading polychlorinated biphenyls were isolated from two soil samples and a river sediment, respectively. The predominant organisms found in all three mixed cultures were Alcaligenes odorans, Alcaligenes denitrificans, and an unidentified bacterium. The polychlorinated biphenyl isomers that were more water soluble and had lower chlorination were not only degraded at a faster rate than those that were less water soluble and had higher chlorination, but were also more completely utilized by these mixed cultures. This resulted in the presence in the environment of polychlorinated biphenyl residues consisting mainly of higher-chlorinated isomers. A form of cometabolism of polychlorinated biphenyls was also found with these cultures in the presence of acetate as the cosubstrate.
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