NILDEMAR APARECIDO MESSIAS FERREIRA
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Artigo IPEN-doc 25088 Sintering behavior of UO2-Er2O3 mixed fuel2018 - DURAZZO, MICHELANGELO; FREITAS, ARTUR C.; SANSONE, ALBERTO E.S.; FERREIRA, NILDEMAR A.M.; CARVALHO, ELITA F.U. de; RIELLA, HUMBERTO G.; LEAL NETO, RICARDO M.The incorporation of burnable neutron absorbers into nuclear fuel pellets is important regarding reactivity compensation, which enables longer fuel cycles. The dry mechanical blending route is the most attractive process to accomplish absorbers incorporation because of its simplicity. By using this route, the present work has investigated the sintering behavior of UO2Er2O3 mixed fuel. A comparison with UO2Gd2O3 sintering behavior was presented. The behavior of UO2Er2O3 fuel sintering was similar to that reported for UO2Gd2O3 fuel, e.g. two-stage sintering with two peaks in the shrinkage rate curves. The effect showed to be less pronounced for Er2O3. This was attributed to the characteristics of the Er2O3 powder particles used as raw-material, whose agglomerates can be more easily broken and thus better homogenized during the blending with UO2 powder. These results confirmed that sinterability depends directly on the quality of the homogenization of the powders, as seen previously. A second phase was experimentally detected in the UO2Er2O3 system, but its impact on the sintering behavior of this mixed fuel has not yet been clarified.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.Resumo IPEN-doc 22202 Microstructural characterization of aluminium alloy AA1050 with ultrafine structure obtained by intense plastic deformation (ECAP)2015 - GUERRA, M.C.L.; MONTEIRO, W.A.; FERREIRA, N.A.M.; SILVA, L.C.E.Resumo IPEN-doc 21723 Compostos nanoestruturados de Na-titanato. Efeito da adição de ZrOsub(2) e de tratamento térmico2015 - USSUI, VALTER; FERREIRA, NILDEMAR A.M.; OLIVEIRA, RENE R.; SANTOS, ANDRE V.P. dos; YOSHITO, WALTER K.; LIMA, NELSON B. de; LAZAR, DOLORES R.R.Artigo IPEN-doc 21525 Síntese química e caracterização de grafeno2015 - CORDEIRO, G.L.; OLIVEIRA, R.R.; FERREIRA, N.A.M.; XAVIER, G.L.; YOSHITO, W.K.; LIMA, N.B.; LAZAR, D.R.R.; USSUI, V.Artigo IPEN-doc 21514 Nanostructured titanate compounds - Effect of ZrOsub(2) addition and its influence on microstructure2015 - SANTOS, A.V.P.; OLIVEIRA, R.R.; YOSHITO, W.K.; FERREIRA, N.A.M.; LIMA, N.B.; LAZAR, D.R.R.; USSUI, V.Artigo IPEN-doc 21512 Efeito dos parâmetros de síntese na formação de compostos nanoestruturados à base de titânia por meio de reação hidrotérmica2015 - SANTOS, ANDRE V.P. dos; YOSHITO, WALTER K.; FERREIRA, NILDEMAR A.M.; USSUI, VALTER; OLIVEIRA NETO, ALMIR; LAZAR, DOLORES R.R.Artigo IPEN-doc 21284 Europium-doped hydroxyapatite: influence of excitation wavelength on the Eusup(3+) luminescence in the hydroxyapatite2015 - SILVA, FLAVIA R.O.; LIMA, NELSON B. de; GOUVEIA, DEIBY S.; FERREIRA, NILDEMAR A.M.; USSUI, VALTER; COURROL, LILIA C.; BRESSIANI, ANA H.A.Resumo IPEN-doc 20357 Síntese e caracterização de hidroxiapatita dopada com európio: influência do tamanho médio do cristalito da HA na emissão e no sítio de ocupação da Eu3+2014 - SILVA, FLAVIA R.O.; GOUVEIA, DEIBY S.; LIMA, NELSON B.; FERREIRA, NILDEMAR A.M.; USSUI, VALTER; SILVA, ANTONIO A.; CORREA, OLANDIR V.; COURROL, LILIA C.; BRESSIANI, ANA H.A.Resumo IPEN-doc 20349 Síntese de alumina mesoporosa por dupla hidrólise2014 - FERREIRA, N.A.M.; CHAGAS, T. de O.; COSENTINO, I.C.; GENOVA, L.A.