Trace element concentrations from São Francisco River - PR analyzed with PIXE technique

Summary Kulcsszavak (angolul, ha nem azonos az elozovel)     

Fusion-fission of light nuclear systems

Considerable interest has been devoted to fusion reactions between light heavy ions specially between weakly bound ones, due to the anomalous decrease of the fusion cross sections when compared to the total reaction cross section in the energy region around the barrier [1–4]. While the exact nature of the process responsible for the fusion cross section limitation at barrier energies is still unclear, this study shows an inhibition of the yield as the system mass decreases, resulting from the progressive increase of the barrier height and decrease of the effective barrier radius [3]. Furthermore, extensive efforts have been made recently in the study of energy-damped binary yields from light heavy-ion collisions [2,4]. Based on the substantial amount of data accumulated so far, it is now generally accepted and supported by the transition state model [4], that the observed yields arise mostly from a fusion-fission process. Data on complete fusion, fusion-fission and ‘elastic fission’ for the ⁹Be, ^10,11B+^10,11B; ^16,17,18O + ^10,11B; ¹⁹F+¹²C; ^6,7Li+⁹Be, ¹²C reactions among others, are presented. For the loosely bound nuclei it was found that the severe fusion cross section limitation is due to a low survival probability of the weakly bound nuclei until the instant of the collision [1].     

Water quality assessment of Toledo River and determination of metal concentrations by using SR-TXRF technique

The region of Toledo River, Paraná, Brazil is characterized by intense anthropogenic activities. Hence, metal concentrations and physical–chemical parameters of Toledo River water were determined in order to complete an environmental evaluation catalog. Samples were collected monthly during one year period at seven different sites from the source down the river mouth, physical–chemical variables were analyzed, and major metallic ions were measured. Metal analysis was performed by using the synchrotron radiation total reflection X-ray fluorescence technique. A statistical analysis was applied to evaluate the reliability of experimental data. The analysis of obtained results have shown that a strong correlation between physical–chemical parameters existed among sites 1 and 7, suggesting that organic pollutants were mainly responsible for decreasing the Toledo River water quality.     

Teeth characterization using ion beam analysis

Summary A collaboration project between the School of Dentistry and the Institute of Physics of the University of S?o Paulo has been established to measure elemental concentrations in teeth by proton induced X-ray emission (PIXE) and heavy ion elastic recoil detection analysis (HI-ERDA) techniques. Data on trace elements in human, bovine and swine teeth, analyzed by PIXE with a 2.4 MeV proton beam, were compared and concentrations for several elements were obtained with tens of mg/g sensitivity. HI-ERDA measurements employing a 52 MeV Cl beam were done to evaluate changes in elementary concentration in dental enamel after bleaching treatment with different products in 25 bovine incisors teeth. This non-destructive technique allowed the measurements of Ca, P, O and C concentrations above the limit of 100 mg/g.