MARCO ANTONIO STANOJEV PEREIRA

MARCO ANTONIO STANOJEV PEREIRA

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Young Scientist Project presents Neutron Life
2023 - ZAMBONI, CIBELE B.; GIOVANNI, DALTON N.S.; KOKA, ANA C.; STANOJEV, MARCO
The Young Scientist Project was created in 2019, by the team of the Spectroscopy and Spectrometry of Radiation Laboratory (LEER/IPEN), with the proposal to implement nuclear knowledge in academia and for the general public. The objective is to develop alternative proposals for knowledge, application and dissemination of nuclear physics using social networks. The website www.jovemcientista.com.br design involves four menus: REPORTS where researchers talk about their career and perspectives in the field; NUCLEAR MINUTE: where nuclear physics concepts are covered in one-minute videos; CURIOSITIES: a space where various themes are presented, including several nuclear applications; INTERVIEWS: conducted by students to discuss its work and a COMMUNICATION CHANNEL with the entire team. All activities involve the participation of students from scientific initiation to post-doc and the content produced is available on social networks YouTube (Jovem Cientista), Instagram (@jovemcientista.com.br) associated with a Facebook page Facebook (@jovemcientista.com.br), TikTok (@jovemcientista.com.br) and by LinkedIn and Twitter in the editors’; profile. Now, we are present a new menu NEUTRON LIFE whose content is produced mainly for graduate students. The idea is to present topics related to neutron physics in a relaxed way, through the elaboration of videos and comic strips. Since the implementation of the Young Scientist Project, interaction with students and the public has been positive, helping to demystify and disseminate nuclear physics.
Fundamentos da química dos elementos
2022 - PEREIRA, MARCO A.S.
Analysis of XX century gold-silver coins by X-ray fluorescence and neutron tomography
2022 - ZAMBONI, C.B.; STANOJEV, M.; KOKA, A.C.S.S.; GIOVANNI, D.N.S.; REDÍGOLO, M.M.
X-ray fluorescence (XRF) is a technique capable of analyzing chemical elements on metallic surfaces, providing fast, sensitive, and reliable results while neutron tomography (NT) allows to investigate its internal structure by three-dimensional images. Both techniques are powerful tools for non-destructive analysis of artistic and historical objects. In this study, we explored the combined use of these techniques to investigate a set of Brazilian gold-silver coins dating from the early 20th century (1913-1938). This set of coins was select due to the lack of data related to their composition and origin. These data provide information to museologists for better cataloging / registration of fundamental information. Moreover, this information is vital for collectors and marchands in authentication processes. The X-Ray Fluorescence analysis was performed using X-Ray Spectrometer with gold (Au) and silver (Ag) targets. The excitation conditions were optimized in 30 kV and 5 μA and counting time of 200 s. A NT facility is installed at the beam-hole (BH-14) of the 4.5 MW pool-type IEA-R1 nuclear research reactor at IPEN (SP, Brazil). It consists of a 6LiF (ZnS) scintillator screen, a glass-based plane mirror, a video camera (16bit, 1024 x1024 pixels, cooled CCD) and a collimator to reduce the neutron beam size in the BH-14. The experimental conditions established were: 8 x106 ns-1 cm-2 (neutron flux), irradiation time/image of 1s, spatial resolution of 263 ± 35 μ and time tomography of 400s. The three-dimensional images were treated using dedicated software (OctopusV8.0 and VG studio Max2.2). The combined results bring information of elemental composition and 3D images highlight the conservation state of the pieces, being of great aid to conservators and museologists.
Corrosion behavior of the 6061 Al–Mg–Si alloy in different soils extracts
2022 - MILAGRE, MARIANA X.; ARAUJO, JOAO V. de S.; MACHADO, CARULINE de S.C.; PEREIRA, MARCO S.; ANTUNES, RENATO A.; GENEZINI, FREDERICO; COSTA, ISOLDA
In this work, the corrosion behavior of the 6061 Al-alloy in different temper conditions was studied in different soil extracts using electrochemical and surface monitoring techniques. The results showed that the corrosion behavior of the 6061 alloy depends on the soil extract composition, with the highest electrochemical activities related to the soil extracts with the lowest nitrate and sulfate concentrations. The 6061-T6 condition was more susceptible to corrosion than the 6061-HCR one. The results were related to the higher amounts of MgSi particles in the 6061-T6 alloy compared to the 6061-HCR. Sulfate and nitrate ions acted as corrosion inhibitor reducing the corrosion kinetics of the 6061 alloy in solutions with high concentration of chloride ions.
Corrosion characterization of the 6061 Al–Mg–Si alloy in synthetic acid rain using neutron tomography
2022 - MILAGRE, MARIANA X.; PEREIRA, MARCO S.; GOMES, ANTONIO A.; SCAPIN, MARCOS; FRANCO, MARGARETH; YOKAICHIYA, FABIANO; GENEZINI, FREDERICO; COSTA, ISOLDA
Neutron tomography has gained increasing importance as an imaging technique for materials characterization. In general, neutron beams are able to show microstructure features of hydrogenous materials, even enfolded with thick metal layers. In the present paper, neutron tomography and observation of cross section images were successfully applied to investigate the corrosion features of the 6061 Al–Mg–Si alloy. The results showed good agreement between neutron 3D tomography and the cross section images obtained in the high attenuation areas of the samples, whereas significant differences in depth of corrosion penetration were obtained between the results from Neutron Tomography and 3D optical profilometry.
Ciência
2020 - PEREIRA, MARCO A.S.
Concentration and distribution of oil in the reservoir mineral Dolomite studied by neutron tomography
2020 - PUGLIESI, R.; STANOJEV PEREIRA, M.A.; ANDRADE, M.L.
Neutron Tomography – NT is a non-destructive technique, ideal for imaging hydrogen-rich substances even when wrapped up by thick rock layers. In the present study, the NT was employed for investigating the oil concentration and distribution in the mineral Dolomite, a natural oil reservoir. Two types of Dolomite samples, one of which dry, and the second one in oil-saturated were prepared. The applied oil was EMCAplus® 070 usually employed in permeability experiments to reproduce conditions of natural oil reservoirs. Three small fragments of the dry sample and three of the oil sample were inspected by NT and the comparison between the obtained results enabled, to distinguish several regions in which the oil is stored, to indicate that the oil is dispersed throughout the volume of the samples, and to quantify the storage concentration. The obtained data for oil concentration, for the three fragments, were compared to each other and to the one obtained by the conventional gravimetric technique, and they agreed within their uncertainties, demonstrating the viability of the NT technique to inspect, either in a qualitative as in a quantitative level, this oil reservoir mineral.
Estudo da mineralização de cobre em basaltos do Grupo Serra Geral, utilizando difratometria de raios X, microscopia eletrônica de varredura-espectroscopia por energia dispersiva e tomografia com nêutrons
2019 - GARDA, GIANNA M.; FILGUEIRA, DIEGO A.; PUGLIESI, REYNALDO; PEREIRA, MARCO A.S.; SAYEG, ISAAC J.
Mineralizações de cobre do tipo Michigan ocorrem nos derrames basálticos do Grupo Serra Geral na região de Nova Prata do Iguaçu, sudoeste do estado do Paraná. Nessas mineralizações, o cobre nativo é o principal mineral de minério e, com a alteração supérgena, transforma-se em óxidos de cobre, malaquita e crisocola, sendo esta encontrada na forma de um precipitado gelatinoso que preenche amígdalas e impregna fraturas no basalto, além de recobrir minerais secundários e outros produtos de alteração. Neste estudo, foram utilizadas as técnicas de difratometria de raios X e microscopia eletrônica de varredura-espectroscopia por energia dispersiva (MEV-EDS) para a caracterização do grau de cristalinidade e composição química da crisocola e a identificação de outros materiais hidrogenados, como subsídio para o imageamento 3D por tomografia com nêutrons. A crisocola destacou-se como um eficiente atenuador de nêutrons, obtendo-se coeficiente de atenuação linear da ordem de 0,8–1,3 cm-1, ao passo que, para o corpo de minério (basalto), obteve-se 0,5–0,6 cm-1. O contraste entre os coeficientes permitiu a obtenção de imagens tomográficas e filmes de boa resolução, em que se pôde visualizar a distribuição da crisocola na amostra de basalto e estimar como fração volumétrica de crisocola no corpo de minério valores entre 0,9 e 1,4%, obtendo-se o valor de 7,8% em volume de crisocola para uma das amostras. A utilização integrada das três técnicas analíticas demonstrou que esta pode ser uma ferramenta para avaliação do potencial mineral nas fases iniciais da prospecção mineral, especialmente quando as substâncias de interesse são ricas em hidrogênio.
Caracterização da mineralização epigenética de cobre na região de Nova Prata do Iguaçu, Estado do Paraná, por microscopia eletrônica de varredura e tomografia de nêutrons
2018 - FILGUEIRA, D.A.; GARDA, G.M.; PUGLIESI, R.; PEREIRA, M.A.S.; SAYEG, I.J.
Dentre os fatores que contribuem para a mineralização epigenética destacam-se a porosidade e a permeabilidade da rocha hospedeira da mineralização. Os fluidos mineralizantes transportam elementos que, dependendo das condições físico-químicas do meio, precipitam-se, podendo vir a formar depósitos minerais. Em Nova Prata do Iguaçu afloram níveis de rocha basáltica mineralizados em cobre, que se apresenta na forma nativa, como óxidos (tenorita, cuprita), como carbonato (malaquita) e silicato (crisocola). A presença de amígdalas, vesículas e geodos na rocha basáltica confere à mesma tanto a permeabilidade necessária para a percolação dos fluidos mineralizantes, como os espaços (vazios) para a precipitação de minerais de minério e minerais secundários associados ou não aos fluidos mineralizantes. Por espectroscopia de energia dispersiva de raios X acoplada à microscopia eletrônica de varredura (EDS/MEV) foram analisados minerais de minério e minerais secundários (analcima, variedades de quartzo, feldspato), dando-se atenção especial à crisocola, cuja variação de cores está relacionada às concentrações de cobre, alumínio e ferro nesse mineralóide. Assim, a crisocola laranja apresenta concentrações de cobre entre 30 e 36% e de alumínio + ferro de até 6%, ao passo que a crisocola azul apresenta concentrações de cobre entre 40 e 41,5% (e não contém alumínio ou ferro). Quanto aos carbonatos e óxidos de cobre, as concentrações de cobre nesses minerais variam entre 62-53% e 74-81%, respectivamente. A técnica da tomografia com nêutrons foi utilizada para investigar a distribuição dos minerais de cobre em amostras de basalto vesicular, empregando-se o equipamento do IPEN-CNEN/SP que está instalado no Reator Nuclear de Pesquisas IEA-R1. Além de não destrutiva, a técnica possibilitou a visualização das estruturas internas do basalto (vesículas preenchidas ou vazias) e a estimativa da proporção em volume de vazios, de cobre nativo e de crisocola. Foram tomografados três amostras de minério e as porcentagens obtidas para os vazios foram 26%, 29% e 31% e a de minerais de cobre 1,1%, 1,7% e 2,4%, respectivamente. O método também se mostrou eficiente no imageamento de cobre nativo. Apesar de não discriminar os silicatos e carbonatos secundários que também preenchem as vesículas do basalto, estes puderam ser identificados por microscopia óptica, difração de raios X e EDS/MEV nos laboratórios do IGc-USP. Assim, o uso da tomografia de nêutrons, associados a técnicas analíticas, como o EDS/MEV, em amostras provenientes de perfis de alteração hidrotermal/intempérico de sequências basálticas contribui para caracterização não só das estruturas da rocha, mas também dos níveis mineralizados e não mineralizados e no entendimento do processo mineralizante.
Study of the fish fossil Notelops brama from Araripe-Basin Brazil by Neutron Tomography
2019 - PUGLIESI, REYNALDO; PEREIRA, MARCO A.S.; ANDRADE, MARCOS L.G.; BASSO, JULIANA M.L.; VOLTANI, CIBELE G.; GONZALES, IVONE C.
In the last decade, Neutron Tomography significantly gained importance as an analyzing tool to inspect samples of paleontological interest. In general, neutrons are able to provide new and complementary information when compared to the ones provided by X-rays imaging methods. Specifically, in the present paper, the Neutron Tomography equipment of the IPEN-CNEN/SP was successfully applied to investigate the internal structure of a fish fossil, embedded in a calcareous concretion. The resulting images, which will be presented, has revealed different contrast between several regions within the specimen enabling the differencing of osteological structures of the fossil, information about its state of conservation, degree of embedding, inclusions as well as regions within the concretion which could be related to humidity or to other substances and minerals containing hydrogen naturally added to the fossil. The technique is non-destructive and non-invasive allowing a close analysis of the specimen. Furthermore, the obtained images have demonstrated the feasibility of the equipment at IPENCNEN/ SP for investigating this kind of sample.