MARIA JOSE AGUIRRE ARMELIN

MARIA JOSE AGUIRRE ARMELIN

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Importance of the neutron activation analysis for the determination of elements in different organic materials
2019 - ARMELIN, MARIA J.A.; MOREIRA, EDSON G.
Instrumental Neutron Activation Analysis (INAA) was the analytical technique used to determine the concentrations of As, Ba, Br, Ca, Ce, Cl, Co, Cr, Fe, La, K, Mg, Mn, Pr, Sb, Sm, V and Zn in the following materials: petroleum, rubber, plastics and petroleum coke. The precision of the results were mostly between 1 and 20%. The technique is non-destructive and fast for Cl, Cu, Mg and V analyses. For this reason, INAA showed to be a good option to be applied in organic matrices.
Concentrations of Se, Ba, Zn and Mn in Brazil nuts
2019 - ARMELIN, M.J.A.; MAIHARA, V.A.; COZZOLINO, S.M.F.; SILVA, P.S.C.; SAIKI, M.
The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples.
Performance of neutron activation analysis in the evaluation of bismuth iodide purification methodology
2017 - ARMELIN, M.J.A.; FERRAZ, C.M.; HAMADA, M.
Bismuth tri-iodide (BiI3) is an attractive material for using as a semiconductor. The behavior of semiconductor devices is strongly influenced by the presence of impurities or contaminants remaining due to incomplete purification of the semiconductor material. BiI3 has emerged as a particularly interesting material in view of its wide band gap (1.7eV), large density (5.7g/cm3), high atomic number elements (Z=68) and high resistivity (>109 cm). The BiI3 crystals have been grown by the vertical Bridgman technique using commercially available powder. In this case, the BiI3 powder was purified three times and, at each purification, the crystal was evaluated by systematic measurements of reduction of impurities, crystalline structure, stoichiometry and surface morphology. The purification efficiency was assessed by analyzing the crystals, through Instrumental Neutron Activation Analysis (INAA). INAA is the elemental analysis method usually chosen for these projects because of some features such as: small amount of sample available, minimal sample handling and high sensitivity for many elements. The analyzed crystals came from the impurity reduction process occurred after each purification by the Repeated Vertical Bridgman method. The results showed that INAA was a special analytical technique to identify and quantify the impurities (Ag, As, Br, Cr, K, Mo, Na and Sb) in the BiI3 crystals and to evaluate the reduction of the trace impurities, after each purification step.
Concentrations of Se, Ba, Zn and Mn in Brazil nuts
2017 - ARMELIN, MARIA J.A.; MAIHARA, VERA A.; COZOLLINO, SILVIA M.F.; CARDOSO, PAULO S.; SAIKI, MITIKO
The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples.
Purification and crystal growth of the bismuth (III) iodide-influence of trace impurities on the crystal quality
2017 - FERRAZ, CAUE de M.; ARMELIN, MARIA J.A.; OLIVEIRA, RENE R.; OTUBO, LARISSA; MARTINS, JOAO F.T.; SANTOS, ROBINSON A. dos; COSTA, FABIO E.; CARVALHO, DIEGO V.S.; OMI, NELSON M.; MESQUITA, C.H.; HAMADA, MARGARIDA M.
This work describes the experimental procedure of purification and preparation of BiI3 crystals by Repeated Vertical Bridgman technique, aiming a future application of this semiconductor crystal as a room temperature radiation detector. The BiI3 powder used as raw material was purified three times and, at each purification, the crystal was evaluated by systematic measurements of the reduction of the impurities, crystalline structure, stoichiometry and surface morphology. The reduction of the trace metal impurities in the BiI3, at each purification, was analyzed by Instrumental Neutron Activation Analysis (INAA), in order to evaluate the efficiency of the purification technique established in this work. It was demonstrated that the Repeated Bridgman technique is effective to reduce the concentration of many impurities in BiI3, such as Ag, As, Br, Cr, K, Mo, Na and Sb. The crystalline structure of the BiI3 crystal purified twice and three times was similar to BiI3 pattern. However, for BiI3 powder and purified once, an intensity contribution of the BiOI was observed in the diffractograms. Improvement in the stoichiometric ratio was observed at each purification step, as well as the crystal surface morphology.
Activity levels of gamma-emitters in Brazil nuts
2016 - ARMELIN, M.J.A.; MAIHARA, V.A.; COZZOLINO, S.M.F.; SILVA, P.S.C.; SAIKI, M.
Activity concentrations of the radionuclides 137Cs, 40K, 226Ra and 228Ra were determined in Brazil nuts acquired at points of sale between 2010 and 2013. Results indicated that the estimated annual effective radioactive dose due to ingestion of Brazil nuts is 27% of the annual dose limit of 1 mSv y-1 for public exposure, according to the Interna-tional Commission on Radiological Protection (ICRP). To estimate this dose the highest activity concentration ob-tained for each radionuclide was considered, assuming an annual consumption of 1.5 kg y-1 per individual.
Characterization of Brazil nut fibers
2016 - INAMURA, P.Y.; KRAIDE, F.H.; ARMELIN, M.J.A.; SCAPIN, M.A.; MOURA, E.A.B.; MASTRO, N.L.
Purification of bismuth(III) iodide for application as radiation semiconductor detector
2015 - FERRAZ, CAUE de M.; ARMELIN, MARIA J.A.; OLIVEIRA, RENE R. de; MARTINS, JOAO F.T.; OMI, NELSON M.; HAMADA, MARGARIDA M.
Performance of neutron activation analysis in the evaluation of bismuth iodine purification methodology
2015 - ARMELIN, MARIA J.A.; FERRAZ, CAUE de M.; HAMADA, MARGARIDA M.
Activity levels of gamma-emitters and barium concentrations in Brazil nuts
2014 - ARMELIN, MARIA J.A.; MAIHARA, VERA A.; COZZOLINO, SILVIA M.F.; SILVA, PAULO S.C. da; SAIKI, MITIKO