SELMA MATHEUS LOUREIRO GUEDES
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Artigo IPEN-doc 28415 Manufacture of non-thrombogenic polymer surfaces by gamma irradiation to induce simultaneous grafting and heparinization of thin PVC films2021 - PANZARINI, LUZ C.G.A.; MORANDIM-GIANNETTI, ANDREIA de A.; GUEDES, SELMA M.L.Investigations regarding alternative methods for producing polymeric materials with hydrophilic properties have increased considerably. In this context, polymeric biomaterials with hemocompatible surface properties have been successfully obtained by grafting hydrophilic monomers onto commercial polymer films by simultaneous irradiation processes. In this study, simultaneous irradiation and grafting were used to produce a copolymer PVC-co-DMAEMA-co-heparin with hemocompatible surface properties. Characterization by FTIR of the graft copolymer indicates that the increase in monomer grafting levels inhibits the bonding sites to heparin. FTIR-PAS analyses of the graft copolymers showed that the highest graft levels were obtained for the irradiated samples containing 45% of monomer. Heparin, however, could only be detected in the irradiated samples containing 30% of DMAEMA. The analysis of the micrographs, on the other hand, showed that increasing the monomer concentration enhances surface roughness of the graft copolymers. Roughness however decreased with heparin addition. It was possible to verify that an excess of surface roughness of the graft copolymers inhibits anticoagulant properties of heparin, triggering thrombus formation. Platelet adhesion, on its turn, was not significantly affected by the presence of heparin when PVC-co-DMAEMA and PVC-co-DMAEMA-co-heparin, obtained from the systems containing 45% of monomer, are compared. The addition of heparin in the systems containing 30% of DMAEMA resulted in fewer thrombogenic surfaces.Artigo IPEN-doc 22537 Influence of a hindered amine stabilizer on optical and mechanical properties of poly(methyl methacrylate) exposed to gamma irradiation2010 - AQUINO, KATIA A.S.; ARAUJO, ELMO S.; GUEDES, SELMA M.L.The ability of Tinuvin 622, a Hindered Amine Stabilizer (HAS), in decreasing of radiation damage to commercial PMMA matrix used in manufacturing of medical supplies was examined. Effects of gamma irradiation in PMMA specimens irradiated at dose range of 10–60 kGy were assessed by comparison of the variation of viscosity average molar mass (Mv) of PMMA with Tinuvin 622 (PMMA- 622) when compared with PMMA without the additive (PMMA-control). Samples containing Tinuvin 622 presented smaller decrease of Mv as a function of dose. This phenomenon causes direct influence in the mechanical properties of PMMA. Above 10 kGy, both PMMA-control and PMMA-622 undergo changes in the yellowness index with increase of absorbed dose; however, the phenomenon was less pronounced for PMMA-622 samples. Electron Spin Resonance spectra showed that Tinuvin 622 induces a faster evolution of radicals formed in PMMA radiolysis followed by a decrease in radiation-induced degradation of the samples.Artigo IPEN-doc 22588 Gamma irradiation effects on poly(hydroxybutyrate)2006 - OLIVEIRA, LETICIA M.; ARAUJO, ELMO S.; GUEDES, SELMA M.L.Artigo IPEN-doc 18875 Boron thin films and CR-39 detectors in BNCT: A method to measure the sup(10)B(n, 'alfa')sup(7)Li reaction rate2013 - SMILGYS, B.; GUEDES, S.; MORALES, M.; ALVAREZ, F.; HADLER, J.C.; COELHO, P.R.P.; SIQUEIRA, P.T.D.; ALENCAR, I.; SOARES, C.J.; CURVO, E.A.C.Artigo IPEN-doc 16359 The energy dependence of selective hydrogen atom abstraction by H(D) atoms in the photolysis of neopentane-ethane mixtures at 77K1980 - MIYAZAKI, TETSUO; GUEDES, SELMA M.L.; FUEKI, KENJIArtigo IPEN-doc 13000 Determination of the sup(238)U spontaneous fission decay constant without neutron irradiation2002 - GUEDES, S.; HADLER, J.C.; IUNES, P.J.; BURKE, A.K.; KAKAZU, M.H.; SARKIS, J.E.S.; PAULO, S.R.; TELLO, C.A.Artigo IPEN-doc 09591 Spontaneous-fission decay constant of sup(238)U measured by nuclear track techniques without neutron irradiation2003 - GUEDES, S.; HADLER NETO, J.C.; SARKIS, J.E.S.; OLIVEIRA, K.M.G.; KAKAZU, M.H.; IUNES, P.J.; SAIKI, M.; TELLO SAENZ, C.A.; PAULO, S.R.Artigo IPEN-doc 04105 Selective hydrogen atom abstraction by hydrogen atoms in photolysis of cyclohexane-normal pentane mixtures at 77K1977 - MIYAZAKI, T.; GUEDES, S.M.L.; SILVA, L.G.A.; FERNANDES, L.Artigo IPEN-doc 04116 Selective hydrogen atom abstraction by hydrogen atoms in photolysis and radiolysis of alkane mixtures at 77K1976 - MIYAZAKI, T.; KINUGAWA, K.; EGUCHI, M.; GUEDES, S.M.L.Artigo IPEN-doc 02935 Efeito da radiacao gama em polimeros usados como imobilizadores de resinas de troca ionica. Parte I: Propriedades do PEBD1996 - HUNG, L.C.; GUEDES, S.M.L.; RIELLA, H.G.