MARIA DA CONCEICAO COSTA PEREIRA

MARIA DA CONCEICAO COSTA PEREIRA

(Fonte: Lattes)

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Possui graduação em Química Industrial pela Escola Superior de Química Oswaldo Cruz (1984), Mestrado pelo Instituto de Pesquisas Energéticas e Nucleares - USP (1997) e Doutorado pelo Instituto de Pesquisas Energéticas e Nucleares - USP (2006). Atualmente é pesquisadora do Instituto de Pesquisas Energéticas e Nucleares. Possui experiência na área de Química e Engenharia Nuclear, atuando principalmente nos seguintes temas: detectores de radiação, tempo de decaimento de luminescência, cintilação e crescimento de cristais cintiladores inorgânicos. Orientadora de Mestrado (Texto extraído do Currículo Lattes em 16 nov. 2021)

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Scintillation characteristics of pure cesium iodide crystals and doped with Tl+, Br- and Li+ ions for use as radiation detectors
2023 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; BERRETTA, JOSE R.; ALVES, JOAO P. da S.
In recent years, more attention has been devoted in the discovery of new scintillators or to improve the characteristics of known scintillators. Today inorganic scintillators are exploited in many new fields such as positron emission tomography (PET) computerized X-ray tomography, space physics and astronomy. Inorganic crystals are the scintillators most commonly used for the detection of gamma rays, X-rays and thermal neutrons. CsI:Tl, CsI:Br, CsI:Li and pure CsI crystals were grown in our laboratory using the vertical Bridgman technique. The concentrations of dopants ranged from 10-1M to 10-4M. The intentional introduction of a certain ion into a crystal depends on physical and chemical properties, that is, the dopant and the matrix. In physical terms, there is a limitation on the volume of ions that can in principle be introduced into the crystal lattice. Furthermore, any substitutional arrangement must preserve the electrical neutrality of the crystal. In chemical terms, one must consider which dopant will accumulate in the phase in which its introduction results in a smaller increase in the free energy of the system. This parameter is represented by the impurity segregation coefficient. It was observed that the wavelength of maximum luminescence emission is characteristic for each crystal. Pure cesium iodide crystal showed maximum intensity of luminescence at the wavelength of 320 nm. The CsI:Tl crystal showed luminescence at a wavelength of 540 nm. CsI:Br and CsI:Li crystals showed maximum luminescence around 420 nm. Analyses were carried out to evaluate the scintillators concerning neutron radiation from AmBe source, with energy range of 1 MeV to 12 MeV. The activity of the AmBe source was 1Ci Am. The fluency was 2.6 x 106 neutrons / second. The crystals response gamma radiation was evaluated in the energy range of 355keV to 1333 keV. In this work, the main optical properties of pure and doped CsI with different ions were studied in order to understand the scintillation mechanism and its application in devices that use the principle of scintillation to detect radiation.
Evaluation of graphene incorporation for mechanical properties of polypropylene composites
2023 - HARADA, JULIO; MARCONDES, CLAUDIO A.; PEREIRA, MARIA da C.C.; SILVA, LEONARDO G.A.
Graphene nanoparticles (GnP) was selected as an alternative reinforcement, nanofillers, to enhance the mechanical properties of polypropylene (PP-homo and PP-copolymer) and using compatibilizer, maleic anhydride graphitized with polypropylene (PP-g-MA) in a twin-screw extruder. The effect of GnP loading and the use of the PP-g- MA compatibilizer were studied. The influence on the mechanical properties of tensile strength, elongation, IZOD impact strength, and melting temperature in PP-homo and PP-copolymer were investigated and compared. Their improvement was observed up to a certain amount, depending on whether it is a homopolymer or copolymer. The PP copolymer has a greater affinity with graphene and the compatibilizer due to the elastomeric comonomer present in the copolymer.
The influence of ionizing radiation on the physical properties of polyester multifilaments
2023 - MELO, CAMILA G.; SILVA, LEONARDO G. de A. e; ROSA, JORGE M.; PEREIRA, MARIA da C.C.
The polyester fibers stand out among the fibers used in the textile industry, due to their numerous factors that make them attractive in terms of cost-effectiveness. The interaction of ionizing radiation with the polyester substrate allows the formation of reactive species capable of stimulating structural modifications of the fiber and, consequently, altering its properties. In this sense, the present work proposes to analyze the influence of ionizing radiation on the physical properties of PES multifilaments. PES multifilament samples were exposed to Cobalt-60 gamma ionizing radiation, with doses ranging from 50 kGy to 200 kGy. The physical properties of tensile strength and elongation were verified. Gamma irradiation treatment proved to be effective in increasing the elongation and strength of the PES multifilament.
Response of CsI:Pb scintillator crystal to neutron radiation
2023 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; BERRETTA, JOSE R.; ALVES, JOAO P. da S.
The helium-3 world crisis requires a development of new methods of neutron detection to replace commonly used 3He proportional counters. In the past decades, great effort was made to developed efficient and fast scintillators to detect radiation.[1] These detectors should, then, be carefully characterized both experimentally and by means of advanced simulation code. Ideally, the detector should have the capability to separate neutron and gamma induced events either by amplitude or through pulse shape differences. As neutron sources also generate gamma radiation, which can interfere with the measurement, it is necessary that the detector be able to discriminate the presence of such radiation. Considerable progress has been achieved to develop new inorganic scintillators, in particular increasing the light output and decreasing the decay time by optimized doping. Crystals may be found to suit neutron detection. In this report, we will present the results of the study of lead doped cesium iodide crystals (CsI:Pb) grown in our laboratory, using the vertical Bridgman technique. The concentration of the lead doping element (Pb) was studied in the range 5x10-4M to 10-2M. The crystals grown were subjected to annealing (heat treatment). In this procedure, vacuum of 10-6 mbar and continuous temperature of 350°C, for 24 hours, were employed. In response to neutron radiation, an AmBe source with energy range of 1 MeV to 12 MeV was used. The activity of the AmBe source was 1Ci Am. The fluency was 2.6 x 106 neutrons/second. The operating voltage of the photomultiplier tube was 1300 V; the accumulation time in the counting process was 600 s and 1800 s. The scintillator crystals used were cut with dimensions of 20 mm diameter and 10 mm height. The Monte Carlo method was used to determine the neutron flux arriving in the detector and the calculated values were obtained by means of MCNP code.
Development and Characterization of the CsI:Tl scintillator grown by the Bridgman technique for use as a radiation detector
2023 - SUZART, KAROLINE F.; PEREIRA, MARIA da C.; MESQUITA, CARLOS H. de; POTIENS, MARIA da P.A.
Emprego de radiação ionizante em efluente de tingimento têxtil com o corante Reactive Black 5 para a avaliação da cor e da toxicidade
2022 - MELO, CAMILA G.; ROSA, JORGE M.; SILVA, LEONARDO G. de A. e; PEREIRA, MARIA da C.C.
Os corantes reativos são os mais empregados no tingimento da fibra de algodão, e se destacam por sua estabilidade química e pelos altos índices de solidez da cor do substrato têxtil. Entretanto, a concentração de corante hidrolisado presente no banho após o tingimento pode chegar a 60% e, somados aos demais compostos orgânicos utilizados, acarretam águas residuais fortemente coloridas e com alta carga de contaminantes. Neste contexto, o objetivo deste estudo foi avaliar a redução da cor e da toxicidade aguda de efluente sintético de tingimento têxtil com o corante Reactive Black 5. O efluente têxtil foi irradiado por meio de acelerador de elétrons, nas doses de 2,5 kGy, 5,0 kGy, 7,5 kGy e 10 kGy, e submetido a análises de toxicidade aguda com o microcrustáceo Daphnia similis e de absorbância, por espectrofotometria visível. Os ensaios de toxicidade aguda apontaram elevada toxicidade do efluente, com valores de CE50 abaixo de 1%. A máxima absorbância do efluente bruto em 590 nm foi de 1,67. O emprego da radiação ionizante por feixe de elétrons proporcionou a redução de 20,69% da toxicidade do efluente na dose de 5 kGy e redução da cor acima de 90%, a partir de 2,5 kGy. A radiação ionizante por feixe de elétrons se mostrou eficaz no tratamento do efluente estudado, para a redução da cor e da toxicidade.
Águas residuais de tingimentos têxteis por processo convencional e após tratamento e reutilização
2022 - MELO, CAMILA G.; BORRELY, SUELI I.; ROSA, JORGE M.; PEREIRA, MARIA da C.C.
A indústria têxtil é destaque mundial, tanto por sua importância econômica, quanto pelas questões ambientais relacionadas à sua cadeia produtiva. As águas residuais provenientes de tingimentos com corantes reativos, possuem características complexas que comprometem os corpos d’água receptores e, consequentemente, a sobrevivência dos organismos aquáticos. Neste contexto, o estudo contemplou a realização de cinco tingimentos consecutivos, usando efluente tratado em cada etapa. Todos os tratamentos fotoquímicos obtiveram Decaimento Absorciométrico (DA) acima de 90%, permitindo que o efluente fosse reaproveitado em novos tingimentos desde o primeiro até o último efluente tratado. No processo proposto, a taxa de Carbono Orgânico Total (COT) obtida após cinco tingimentos consecutivos com o efluente tratado foi de 34 mg L-1, em comparação aos 435 mg L-1 do efluente obtido após cinco processos convencionais. A Salinidade do efluente final obtida pelo processo proposto foi de 2,34 g L-1 de NaCl, comparada a concentração de 25 g L-1 apresentada no efluente pelo processo convencional. O consumo médio de água para um tingimento de algodão de um quilograma, pelo processo proposto, foi de aproximadamente 24 litros, em comparação aos 70 litros consumidos pelo processo convencional. No entanto, o efluente tratado apresentou valores de toxicidade < 6,25% (CE50, com intervalo de confiança de 95%) contra 10,25% do efluente bruto (sem tratamento). A concentração mediana, que causou a imobilidade dos organismos expostos, indicou a maior sensibilidade do microcrustáceo Daphnia similis ao efluente tratado.
Zonal refining and Bridgman technique for CsI:Tl scintillation crystal growth
2022 - SUZART, K.F.; PEREIRA, M.C.C.; HAMADA, M.M.; MESQUITA, C.H.
This work describes the development of the crystal cesium iodide doped with thallium (CsI:Tl) for use as a radiation detector. For CsI salt purification the zonal refining methodology using a horizontal oven at a constant temperature of 700 °C was used. The high temperature region corresponds to approximately 10% of the salt bed containing (260 mm). This region moves at a speed of 50 mm/h. The crystal growth was carried out by Bridgman technique, using a vertical oven at speed of 1 mm/h.
The growth and scintillation characteristics of lithium doped CsI crystals
2011 - PEREIRA, MARIA da C.C.; CARDENAS, JOSE P.N.; MADI FILHO, TUFIC
Inorganic scintillators play an important role in the detection and spectroscopy of gamma and X-rays, as well as in neutrons and charged particles. For a variety of applications, new inorganic scintillation materials are being studied. New scintillation detector applications arise continuously and the interest in the introduction of new fast scintillators becomes relevant. Scintillation crystals based on cesium iodide (CsI) have relatively low hygroscope, easy handling and low cost, features that favor their use as radiation detectors. In this work, lithium doped CsI crystals were grown using the vertical Bridgman technique. In this technique, the charge is maintained at high temperature for 10 h to for the material melting and complete reaction. The temperature gradient 21° C/cm and 1 mm/h descending velocity are chosen as technique parameters. After growth is finished, the furnace is cooled at a rate of 20° C/h to room temperature. The concentration of the lithium doping element (Li) studied was 10-3 M. Analyses were carried out to evaluate the scintillator developed concerning two responses: a) to the gamma radiation, in the energy range of 350 keV to 1330 keV and b) to neutron from AmBe source, with energy range of 1MeV to 12 MeV. T.S. Korolevaa et al [1] describe in their paper about new scintillation materials, for registration of gamma-rays, X-rays, neutrons and neutrinos. One of these materials is 6Li. Lithium can capture neutrons without gamma-ray emission and, thus, reducing the back-ground. The neutron detection reaction is 6Li(n,a)3H with a thermal neutron cross section that 940 barns. In this paper we investigated the feasibility of the CsI:Li crystal as a gamma ray and neutron detector which can be used for monitoring, due to the fact that in our work environment we have two nuclear research reactors, calibration systems and radioisotope production.
Determination of the bromine, manganese and antimony in Nicotiana tabacum solanaceae by using the neutron activation analysis technique
2022 - MADI FILHO, TUFIC; FERREIRA, ELSON B.; BERRETTA, JOSE R.; PEREIRA, MARIA da C.C.
Tobacco addiction has been mentioned as a leading cause of preventable illnesses and premature disability. Smoking is the main cause of lung cancer and one of the factors that most contribute to the occurrence of heart diseases, among others. The herbaceous species Nicotiana tabacum is a plant of the solanaceae family used for tobacco production. Some authors have conducted research about heavy metals and the toxicity of tobacco. It is, frequently, found in low concentrations in the ground, and superficial and underground waters, even though they do not have environmental anthropogenic contributions. However, with the increase of industrial activities and mining together with the agrochemical use of contaminated organic and inorganic fertilizers, an alteration of the geochemical cycle occurs. As a consequence, the natural flow of these materials increases and is released into the biosphere, where they are often accumulated in the superior layer of the ground, accessible to the roots of the plants. During planting and plant development, fertilizers and insecticides, including organochlorines and organophosphates, are used; consequently, the smoke from cigarette smoking presents various toxic substances, such as bromine (Br), manganese (Mn) and antimony (Sb), elements studied in this work. The procedures for the preparation of the samples were carried out in our laboratories and submitted to irradiation with thermal neutrons at Nuclear and Energy Research Institute (IPEN/CNEN-SP), in the Atomic Energy Institute IEA-R1 research reactor. The irradiated material was, then, analyzed by gamma spectrometry, using a high purity germanium detector (HPGe).