RICARDO MARCELO PIASENTIN
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Artigo IPEN-doc 23720 Effect of Sn loading on the characteristics of Pt electrocatalysts supported on reduced graphene oxide for application as direct ethanol fuel cell anode2017 - CORDEIRO, GUILHERME L.; USSUI, VALTER; MESSIAS, NILDEMAR A.; PIASENTIN, RICARDO M.; LIMA, NELSON B. de; NETO, ALMIR O.; LAZAR, DOLORES R.R.The effect of Sn loading (5–30 mol %) on Pt catalysts supported on reduced graphene oxide was investigated for ethanol electro-oxidation in acidic medium. Reduced graphene oxide was synthesized via graphite oxidation–exfoliation process in liquid phase and chemical reduction. Pt and PtxSny catalysts were deposited on reduced graphene oxide by a NaBH4 impregnation–reduction method. The adopted procedures allowed the synthesis of graphene-like nanosheets where single Sn-doped Pt nanoparticles were impregnated. Pt lattice parameter and micro-strain increased with Sn addition, confirming the formation of a solid solution. Concerning ethanol electro-oxidation, Pt was more active when supported on reduced graphene oxide whereas the introduction of Sn enhanced the catalyst activity, leading to lower ethanol oxidation potentials and higher current densities.Artigo IPEN-doc 09586 Effect of chelated mineral supplementation on the absorption of Cu, Fe, K, Mn and Zn in horse hair2003 - ARMELIN, M.J.A.; AVILA, R.L.; PIASENTIN, R.M.; SAIKI, M.The supplement effect of Cu, Fe, K, Mg, Mn and Zn chelated with glycine on the absorption of these elements by animals was evaluated. The evaluation was carried out by comparing the mineral concentrations found in hair of the animals before and after 47 days of supplementation with a combination of glycine-mineral chelates. Five horses known to be clinically well were used for this study. Instrumental neutron activation analysis (INAA) was applied to the determination of Cu, Fe, K, Mg, Mn and Zn concentrations in the horse hair samples. It was observed that the supplementation helps the Fe, K and Zn absorption by the animal organism. The data obtained suggest that the hair is a suitable material to investigate Fe, K and Zn in mineral metabolism in the animal organism.Artigo IPEN-doc 08252 Application of neutron activation analysis to evaluate the health status of equines by means of Cu, Fe, Mn and Zn determinations in their hair2001 - ARMELIN, M.J.A.; AVILA, R.L.; PIASENTIN, R.M.; SAIKI, M.Instrumental neutron activation analysis (INAA) was applied to evaluate the clinical status of equines, belonging to the Military Police of São Paulo State, by means of Cu, Fe, Mn and Zn determinations in their hair. Comparison of the results obtained in these analyses with reference values indicated Zn deficiency in the equines, Fe is in the minimum limit and the elements Cu and Mn are within the normal range.Artigo IPEN-doc 07119 Effects of fertilizer with different mineral composition on the absorption of Ca, Cu, K, Mg, Mn, Na and V, by two cultivars of pigeonpea (Cajanus cajan, Millsp)2001 - PIASENTIN, R.M.; ARMELIN, M.J.A.; PRIMAVESI, O.; SAIKI, M.Seventy-two leaf samples belonging to two cultivars of Cajanus cajan Millsp were analysed by instrumental neutron activation analysis (INAA). The samples came from plants treated with two doses of fertilizer containing each of the following elements: B, Co, Cu, Fe, Mn, Mo, V and Zn, which were applied, individually, to the soil. The leaf samples were yielded at two different times. The purpose of this paper is to elucidate the influence of each fertilizer, the dose and leaf harvest time, on the concentrations of Ca, Cu, K, Mg, Mn, Na and V, and the behavior of both cultivars in relation to the concentrations of these elements.Artigo IPEN-doc 08641 Neutron activation analysis of zinc in forages used in intensive dairy cattle production systems2002 - ARMELIN, M.J.A.; PIASENTIN, R.M.; PRIMAVESI, O.