Adequacy of commercial lentogenic vaccines against Canadian strains of viscerotropic Newcastle disease virus.

Three field strains of Newcastle Disease virus, designated S20, S21 and S23, isolated from chickens or turkeys in Ontario during the 1971-72 epizootic, were characterized as velogenic viscerotropic viruses. No significant antigenic differences were demonstrated among B1, LaSota and a field strain (S23) of velogenic vescerotropic virus by haemagglutination inhibition or protection tests. Primary water vaccination of chicks with commercial B1 and LaSota vaccines at five weeks of age and aerosol revaccination with the same strains four weeks later resulted in protection that lasted 16 weeks after revaccination against experimental challenge with strain S23. The differences in haemagglutination inhibition titres noted when the homologous or the heterologous viruses were used as haemagglutinating antigen were not statistically significant. The rates of decay of virus neutralizing and haemagglutination inhibition antibodies in vaccinated birds showed a divergence indicating the possible duality of antibodies measured in serum neutralization and haemagglutination inhibition tests.     

Removal of paraquat by adsorption on ‘waste’ Fe(III)/Cr(III) hydroxide: Adsorption rates and equilibrium studies

The ability of ‘waste’ Fe(III)/Cr(III) hydroxide to adsorb paraquat has been investigated. Effects of contact time, initial concentration and pH, adsorption capacity and desorption have been studied. Adsorption followed a first-order expression. The adsorption rate constant decreased from 1–84 to 0–50 min^?1 with the increase of paraquat concentration from 10 to 40 mg litre^?1. Adsorption obeyed the Freundlich isotherm and the K₁ value was found to be 0.1995. A maximum removal of 93% was attained at pH 1204. Desorption with water occurred to the extent of 39% indicating that physical sorption was partly responsible in the adsorption process.