Experimental design methodology applied to adsorption of metallic ions onto fly ash.

The objective of this study was to define operating conditions which would conciliate a high removal of the five metallic cations (Cu2+, Ni2+, Zn2+, Cd2+, Pb2+) and a low desorption of these metal ions from the contaminated sorbents. To achieve this goal the strategy relied on the use of experimental design methodology. The influence of four parameters (fly ash/lime mass ratio, type of fly ash/lime sorbent, solution temperature, and sorbent concentration) on the removal at pH = 5 and the stabilization of the five metallic ions was studied.

Diversity of ribosomal DNA fingerprints of Leptospira serovars provides a database for subtyping and species assignation.

Ribosomal DNA fingerprints from 103 pathogenic Leptospira strains were examined using EcoRI restriction and fragment length polymorphisms of rRNA genes. Sixty-nine new leptospiral ribotypes were described, in addition to 49 previously observed. Except for 5 strains, a good correlation between DNA homology data and ribotyping was observed.