Colonização ictiofaunística do Reservatório de Itaipu e áreas adjacentes Ichthyofaunistic colonization of the Itaipu Reservoir and vicinity áreas

<abstract language="eng">Samples were taken from November 1983 to October 1989 in sites along the main body of the Itaipu reservoir and its area of influence to evaluate the impacts of this reservoir on ichthyofauna and to provide information about the colonization process in the dammed area. The ichthyofaunistic similarity between the sites was analysed during the studied period. Spatial and temporal variations of the ichthyofaunistic diversity were also done, using Shannon-Winer Index of Diversity, eveness and species richness, comparing the results with those obtained before the damming. After Itaipu Reservoir formation, it was observed significative alteration in specific abundance and ichthyofauna structure of the Paraná River, with an increase in species number in ali tributaries of the reservoir, and a high replacement in species. Diversity and species richness were higher in the dammed stretch of the Paraná river and in its tributaries of the left side after the Itaipu reservoir formation. Among the sampled sites, the highest values of the diversity index were registered in Paraná River upstream and downstream the reservoir, Iguatemi river and Arroio Guaçu. Based on information of similarity in species composition and abundance in the sampled area, five site groups could be identified

Ferromagnetism in Rh-doped SnO 2 from first-principles calculation

The electronic structures and magnetic properties for Rh-doped SnO 2 crystals have been investigated by density functional theory. The results demonstrate a magnetic moment, which mainly arises from d orbital of Rhodium, of 1.0 μ B per Rhodium with a little contribution from the Oxygen atoms surrounding it. The Rh-doped SnO 2 system exhibits half-metallic ferromagnetism with high Curie temperature. Several doped configurations calculations show that there are some robust ferromagnetic couplings between these local magnetic moments. The p–d hybridization mechanism is responsible for the predicted ferromagnetism. These results suggest a recipe obtaining promising dilute magnetic semiconductor by doping nonmagnetic elements in SnO 2 matrix. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2011