A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

O teste de micronúcleo é freqüentemente usado em dosimetria biológica. Devido à alta variabilidade interindividual na freqüência espontânea de micronúcleos, sua sensibilidade em pequenas doses é baixa. Tem sido sugerido que este problema pode ser atenuado analisando-se seletivamente a freqüência daqueles micronúcleos que contêm apenas fragmentos acêntricos. Usando uma sonda de FISH pan-centromérica, nós estudamos a dependência de micronúcleos com centrômeros em linfócitos periféricos de doadores humanos, com relação à dose. Ao contrário de publicações anteriores, nossa abordagem se baseia na determinação da freqüência relativa de micronúcleos com e sem sinais centroméricos. Nossos resultados confirmam observações anteriores de que, na faixa de baixas doses de radiação ionizante, o teste de micronúcleo-centrômero é mais sensível do que o teste de micronúcleo convencional.

The micronucleus assay is frequently used for purposes of biological dosimetry. Due to high interindividual variability in the spontaneous frequency of micronuclei, its sensitivity in the low dose region is poor. It has been suggested that this problem can be mitigated by selectively analyzing the frequency of those micronuclei which contain only acentric fragments. Using a pan-centromeric FISH probe we have studied the dose dependence of micronuclei with centromeres in peripheral lymphocytes of human donors. In contrast to previous publications, our approach is based on determining the relative frequency of micronuclei with and without centromeric signals. Our results confirm previous observations that in the low dose range of ionizing radiation, the micronucleus-centromere assay is more sensitive than the conventional micronucleus test.