INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES
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BibliotecaTerezine Arantes Ferraz

Navegação Eventos - Artigos por Agências de fomento "Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)"

Navegação Eventos - Artigos por Agências de fomento "Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)"

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  • IPEN-DOC 26077

    ANA, PATRICIA A.; PEREIRA, DAISA de L. ; FERREIRA, ELIZABETE dos S.; FIGUEREDO, DANIELA C.; DAGUANO, JULIANA K.F.B.; ZEZELL, DENISE M. . Advances in the prevention and monitoring of root dentin demineralization using lasers. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, October 7-9, 2019, São Paulo, SP. Proceedings... 2019.

    Abstract: The increase in the life expectancy and the longer permanence of the teeth in the oral cavity also led to an augment in the prevalence of root caries lesions. These lesions require more attention because of their rapid progression and difficulty in early diagnosis and monitoring. In this context, the irradiation of the tissues with high intensity lasers has been shown as an important way for preventing lesion formation because lasers chemically modify the irradiated dental hard tissues and make them more resistant to acid challenge. In addition, the association with ceramic biomaterials may allow additional remineralizing results. Together with therapeutics, the effective early diagnosis of incipient lesions is indispensable. Techniques that use lasers, such as optical coherence tomography, have also been promising in this aspect because they allow the early diagnosis and monitoring of demineralizations with high resolution and in a non-detrimental way. This article aims to show the actions of high intensity laser therapies when associated or not with biomaterials, on the prevention and remineralization of root caries lesions, as well as the effectiveness of optical coherence tomography in the diagnosis and monitoring the effects of the treatments in these lesions.

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  • IPEN-DOC 26762

    SIERRA, JULIAN H.; CARVALHO, DANIEL O.; SAMAD, RICARDO E. ; RANGEL, RICARDO C.; ALAYO, MARCO I.. Analysis and measurement of the non-linear refractive index of SiOxNy using pedestal waveguides. In: SYMPOSIUM ON MICROELECTRONICS TECHNOLOGY AND DEVICES, 34th, August 26-30, 2019, São Paulo, SP. Proceedings... Piscataway, NJ, USA: IEEE, 2019. DOI: 10.1109/SBMicro.2019.8919392

    Abstract: In this work, the non-linear refractive index (n2) of silicon oxynitride (SiOxNy) is determined, obtaining a value for this material of n2 = 2.11×10-19 m2/W. The results demonstrate that this material has interesting properties for the development of non-linear optical devices. The paper presents in detail the waveguide fabrication process using the pedestal technique, which allows using different materials since it does not require etching to define the sidewalls of the waveguides. We show the results of the measurement of the n2 employing the non-linear optical phenomena of Self-Phase Modulation (SPM).

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  • IPEN-DOC 26133

    ABREU, RODRIGO T. ; ANGELOCCI, LUCAS V. ; NOGUEIRA, BEATRIZ R. ; SANTOS, HAMONA N. dos ; ZEITUNI, CARLOS A. ; ROSTELATO, MARIA E.C.M. . Anisotropy function of a new 192-Ir brachytherapy source. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 175-185.

    Abstract: Brachytherapy is a type of radiotherapy that uses radioactive sources (seeds, wires, among others) close to the tumor. Is important to provide a detailed description of seed dosimetry, so only the tumor will be irradiated avoiding unnecessary dose on adjacent organs and structures. To evaluate the dosimetric parameter of the anisotropy function for a new brachytherapy source, this work proposes the use of microcube TLD-100 dosimeters to find the dose rate using the AAPM Task Group 43 protocol (TG-43). The anisotropy function represents dose distribution around the source and has a major role for characterization of a new iridium source being implemented in Brazil. The value of D(r,θ) was measured using Solid Water phantoms, r value being the distance from the geometric center of the source to the position of the dosimeter on the phantom, and θ being the angle formed between the longitudinal axis of the source and the line connecting the geometric center to the TLD. Monte Carlo calculations were performed to evaluate the anisotropy function to validate the experimental measurements. For each distance value (r), an anisotropy function was plotted (1.0, 2.0, 3.0, 4.0, 5.0, and 10.0 cm). The results obtained with Monte Carlo calculations agreed ±2% with the experimental values for r greater than 3.0 cm, so these results show a good distribution of dose around the seed considering the high energy of 192-Ir (average of 380 KeV) and encapsulation thickness.

    Palavras-Chave: anisotropy; brachytherapy; dose rates; dosimetry; iridium 192; monte carlo method; phantoms; radiation dose distributions; radiation source implants; sealed sources; thermoluminescent dosemeters

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  • IPEN-DOC 24876

    OLIANI, WASHINGTON L. ; PARRA, DUCLERC F. ; KOMATSU, LUIZ G.H. ; LINCOPAN, NILTON; RANGARI, VIJAYA K.; LUGAO, ADEMAR B. . Antibacterial effect of silver incorporated polyethylene blown film for active packaging use. In: CONGRESSO BRASILEIRO DE POLIMEROS, 14., 22-26 de outubro, 2017, Águas de Lindóia, SP. Anais... 2017. p. 2433-2437.

    Abstract: Food packaging is used to maintain the quality and safety of food products during storage and transportation, and to extend the shelf-life of food products. This is done by preventing unfavourable factors or conditions such as oxygen, light, moisture, spoilage microorganisms, chemical contaminants, mechanical resistance, etc. To be able to do so, packaging materials provide physical protection and also create the proper physicochemical conditions for each product necessary to obtain adequate shelf life and maintain food quality and safety. We report the preparation of polyethylene blown films containing silver nanoparticles by using the ultrasound technique. The silver nitrate was mixed with the surfactant oleic acid (AO) and sonicated for 30 minutes. This solution was mixed with polyethylene using a rotary mixer for 12 hours. Nanocomposites of low density polyethylene (LDPE) with linear low density polyethylene (LLDPE) blends and silver nanoparticles were prepared under melt in a twin screw extruder, using PE-g-MA as compatibilizer agent, ethylene graft maleic anhydride copolymer. The films were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), percentage reduction of colony-forming units (CFU). The bacterial effect of Escherichia coli and Staphylococcus aureus were assessed in detail.

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  • IPEN-DOC 26141

    COTIS, DÉBORA S.; MARQUES, LEILA S.; FIGUEIREDO, ANA M.G. ; CORVAL, ARTUR; VALENTE, SÉRGIO C.. Application of neutron activation analysis to the study of low-titanium tholeiitic dykes of the Serra do Mar Swarm (RJ). In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 330-343.

    Abstract: The tholeiitic dykes of the Serra do Mar Swarm (SMS) outcrop along the coast of the São Paulo and Rio de Janeiro states (Southeastern Brazil), spreading over the Rio Paraiba Valley. Previous studies carried out in such dykes showed that they are related to the tectonic and magmatic processes that took place during the South Atlantic Ocean opening and gave rise to the Paraná Magmatic Province (PMP). The dykes are vertical to subvertical and preferentially NE-SW trending, with thicknesses ranging from centimeters to tens of meters. Most of the SMS intrusive rocks have relatively high concentrations of TiO2 (>3wt%), except for occurrences in the Região dos Lagos (Costa Azul Suite), as well as around Nova Friburgo Town (Serrana Suite), where they are characterized by basic rocks with low TiO2 (<2wt%) contents, whose genesis are still not completely understood. Therefore, a detailed study is being carried out in rocks of the Suite Serrana, with the determination of the concentrations of the rare earth (REE: La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) and other trace (Ta, Th, U, Hf, Cs, Sc, and Co) elements by instrumental neutron (thermal and epithermal) activation analysis, which has accuracy and precision required for petrogenetic studies. The data obtained so far show a substantial enrichment of highly incompatible trace elements (light REE, Th and U) and a remarkable geochemical similarity with the low-TiO2 basaltic flows of Gramado type found in southern PMP, suggesting important processes of crustal contamination during the genesis of the investigated dykes.

    Palavras-Chave: elements; geology; igneous rocks; neutron activation analysis; radioisotopes; titanium; trace amounts; brazil

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  • IPEN-DOC 26766

    LIMA, CASSIO A. ; CORREA, LUCIANA; BYRNE, HUGH J.; ZEZELL, DENISE M. . Assessing the spectrochemical signatures of skin components using FTIR microspectroscopy. In: QUINCY BROWN, J. (Ed.); VAN LEEUWEN, TON G. (Ed.) EUROPEAN CONFERENCES ON BIOMEDICAL OPTICS, June 23-27, 2019, Munich, Germany. Proceedings... Bellingham, WA, USA: SPIE, 2019. p. 110730S-1 - 110730S-3. (Proceedings of SPIE-OSA Vol. 11073, Clinical and Preclinical Optical Diagnostics II). DOI: 10.1117/12.2527137

    Abstract: Fourier Transform Infrared (FTIR) spectroscopy is a label-free analytical technique used to evaluate the chemical profile of a sample based on its molecular vibrations. The potential dermatological applications of FTIR spectroscopy has been well demonstrated over the past decades through many proof-of-concept studies evaluating cancerous and non-cancerous cutaneous diseases. Considering that the correctly identification of skin components plays an important role in the study of cutaneous diseases, the present study aims to evaluate the spectrochemical signatures of dermis and epidermis based on the pixels of a FTIR hyperspectral image collected from healthy skin.

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  • IPEN-DOC 25607

    CASTRO, PEDRO ; ZORN, TELMA; ZEZELL, DENISE . Biochemical characterization of skin burn wound healing using ATR-FTIR. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, October 08-10, 2018, Campinas, SP. Proceedings... Piscataway, NJ, USA: IEEE, 2018. DOI: 10.1109/SBFoton-IOPC.2018.8610943

    Abstract: Efficient biochemical characterization of skin burn healing stages can improve clinical routine to adjust patients treatment. The golden standard for diagnosing skin burning stages is the histological biopsy. This practice is often expensive and technically challenging. There have been advances in the treatment, and diagnostic of the critical skin burned patients due to the increase of multidisciplinary collaboration. The contributions from different fields of biomedical engineering motivate to develop a better procedure for clinical applications. Considering the difficulty of monitoring wound healing the Fourier Transform Infrared coupled with an Attenuated Total Reflectance (ATR-FTIR) accessory is an analytical technique that can provide information regarding spectral biomarkers in biological materials. This study aimed to evaluate the classification feasibility provided by ATR-FTIR technique in the burned skin to follow the regenerative process in vivo. 40 skin burned samples from the Wistar rats dorsum at 3,7, 14, 21 days after burn were compared with the corresponded healthy group samples, by registering their infrared absorption spectra in FTIR Thermo Nicolet 6700 coupled to a diamond crystal ATR. The spectra were separated in the region 900 to 1800 cm-1 for further chemometric calculations. The second derivative of spectra was applied for discrimination, which results demonstrated differences from control and burns wounded groups, as well as among, burn wounded groups, using Amide I (1628 cm-1) and Amide II (1514 cm-1) bands. Amide I and Amide II bands are two significant bands of the infrared protein spectrum. The Amide I band is mainly associated with the C=O stretching vibration (70-80%) and is directly related to the backbone conformation. The Amide II band results from the N-H bending vibration (40-60%) and from the C-N stretching vibration (18-40%). This band is conformationally sensitive. These bands suggest proteins activity changing associate to inflammatory and maturation stages when it is compared with the healthy group. The statistical difference with amide I occur in proliferation and maturation stages. These findings indicate that ATR-FTIR is suitable to detect the burn wound healing stages and in the future can be an auxiliary instrument for clinical routine.

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  • IPEN-DOC 26784

    LITVAC, DANIEL ; CALDAS, LINDA V.E. . Calibration of a clinical beta therapy applicator using the thermoluminescence samples: preliminary results. In: CONGRESSO BRASILEIRO DE METROLOGIA, 10.; CONGRESSO INTERNACIONAL DE METROLOGIA ELÉTRICA, 13.; CONGRESSO INTERNACIONAL DE METROLOGIA MECÂNICA, 5.; CONGRESSO BRASILEIRO DE METROLOGIA DAS RADIAÇÕES IONIZANTES, 6.; WORKSHOP DA REDE DE METROLOGIA QUÍMICA DO INMETRO, 4.; CONGRESSO BRASILEIRO DE METROLOGIA ÓPTICA, 3., 24-27 de novembro, 2019, Florianópolis, SC. Anais... Rio de Janeiro, RJ: Sociedade Brasileira de Metrologia, 2019.

    Abstract: In some parts of Brazil, 90Sr/90Y clinical applicators are still used for dermatological and ophthalmic treatments, even with the higher efficiency of linear accelerators because they are of lower cost and easier use. Calibration and periodic recalibration of these applicators to verify the absorbed dose rate is essential to ensure accuracy in clinical treatments. In this work the thermoluminescent response of BeO and μLiF pellets was evaluated, determining the reproducibility, linearity of response and their dose-response curves. This standard, for this type of calibration, recommends the use of small detectors such as μLiF. Therefore, the utility of μLiF and BeO in the calibration of clinical applicators was compared.

    Palavras-Chave: beryllium oxides; lithium fluorides; beta particles; calibration; comparative evaluations; dosimetry; radiation sources; therapy; thermoluminescence

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  • IPEN-DOC 25545

    LITVAC, DANIEL ; CALDAS, LINDA V.E. . Caracterização dosimétrica do BeO para calibração de aplicadores clínicos de betaterapia. In: CONGRESSO BRASILEIRO DE METROLOGIA DAS RADIACOES IONIZANTES, 26-28 de novembro, 2018, Rio de Janeiro, RJ. Anais... 2018. p. 1-8.

    Abstract: Aplicadores clínicos de 90Sr + 90Y ainda são utilizados em algumas partes do Brasil para tratamentos dermatológicos e oftálmicos, mesmo com a recomendação do uso de aceleradores lineares, porque são de custo mais baixo e práticos. A calibração e a recalibração periódica destes aplicadores, para verificação da taxa de dose absorvida, são essenciais para garantir a segurança nos tratamentos clínicos. Neste trabalho foi avaliada a resposta termoluminescente de pastilhas de BeO e se são aplicáveis a um planejamento de calibração de aplicadores clínicos de betaterapia, porque o material dosimétrico que era utilizado neste planejamento não é mais produzido no IPEN.

    Palavras-Chave: beryllium oxides; beta dosimetry; brazilian cnen; calibration; recommendations; thermoluminescence; yttrium 90

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  • IPEN-DOC 26758

    ROVANI, S. ; CARVALHO, F. ; SANTOS, J.; RAMOS, N.; MORANDI, M.; SALDANHA, M.; FUNGARO, D. . Caracterização físico-química das propriedades de cinzas de cana-de-açúcar de diferentes usinas brasileiras. In: CONGRESSO BRASILEIRO DE QUÍMICA, 59., 5-8 de novembro, 2019, João Pessoa, PB. Anais... Rio de Janeiro, RJ: Associação Brasileira de Química, 2019.

    Abstract: O interesse em transformar biomassa em novas fontes de energia e novos materiais vem fomentando estudos em todo o mundo. As cinzas resultantes da queima de palha e bagaço de cana, por exemplo, é um material rico em sílica. No presente estudo, amostras de cinzas de resíduos de cana-de-açúcar foram coletadas nas usinas de Cerradinho (Chapadão do Céu, GO), Iracema (Iracemápolis, SP) e Guaíra (Guaíra, SP), localizadas em regiões onde os solos são classificados como Latossolos. As cinzas foram caracterizadas pelas técnicas de XRD, EDX, MEV, espectroscopia no IV e DTG. A maioria das amostras de cinzas apresentou sílica como principal constituinte (42-69%) e a sílica na forma cristalina em todas. Diferenças significativas nas concentrações de outros elementos foram observadas.

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  • IPEN-DOC 27026

    PEREIRA, T.M. ; DIEM, M.; BIRD, B.; MILJKOVIC, M.; ANA, P.A.; BACHMANN, L.; ZEZELL, D.M. . Caracterização por espectroscopia no infravermelho de colóides tireoidianos sadios e hiperplásicos. In: CONGRESSO BRASILEIRO DE ENGENHARIA BIOMÉDICA, 24., 13-17 de outubro, 2014, Uberlândia, MG. Anais... Bauru, SP: Canal 6, 2014. p. 1115-1118.

    Abstract: O presente trabalho mostra a caracterização da Tiroglobulina contidos nos colóides tireoidianos por espectroscopia no infravermelho. A produção da tiroglobulina é alterada em pacientes com Bócio Nodular. Assim, as informações bioquímicas desta glicoiodoproteina podem ser utilizada como indicador desta disfunção. Os resultados utilizando espectroscopia no infravermelho revela diferenças bioquímicas nas conformação da proteína, hormônios e carboidratos.

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  • IPEN-DOC 26744

    VILLANI, D. ; SAVI, M. ; ANDRADE, M.A.B.; CAMPOS, L.L. ; POTIENS, M.P.A. . Characterization of ABS + W and ABS + Bi 3D printing filaments attenuation for different photon beams. In: CONGRESSO BRASILEIRO DE METROLOGIA, 10.; CONGRESSO INTERNACIONAL DE METROLOGIA ELÉTRICA, 13.; CONGRESSO INTERNACIONAL DE METROLOGIA MECÂNICA, 5.; CONGRESSO BRASILEIRO DE METROLOGIA DAS RADIAÇÕES IONIZANTES, 6.; WORKSHOP DA REDE DE METROLOGIA QUÍMICA DO INMETRO, 4.; CONGRESSO BRASILEIRO DE METROLOGIA ÓPTICA, 3., 24-27 de novembro, 2019, Florianópolis, SC. Anais... Rio de Janeiro, RJ: Sociedade Brasileira de Metrologia, 2019.

    Abstract: 3D printing techniques and materials have become widely available in the last couple of decades and remains a hot topic of study as new materials can lead to new applications. This study aims to evaluate the attenuation behaviour of GMASS over photon beams ranging from 29.7 up to 661.7keV, comparing with pure ABS and using theoretical data of pure lead as reference. It was used the transmission method to obtain experimental attenuation coefficients to all materials and theoretical data. HVL and TVL calculations were also performed. Results show that ABS+W has higher attenuation than ABS+Bi and pure ABS. Using the lead theoretical reference data it can be concluded that although ABS+Bi and ABS+W attenuates less than pure lead, the 3D printing filaments can be used to create shielding tolls depending on radiation energy and application.

    Palavras-Chave: attenuation; cesium 137; dosimetry; energy dependence; filaments; photon beams; polymers; radiations; shielding

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  • IPEN-DOC 24103

    CASTRO, PEDRO A.A. de ; DIAS, DERLY A. ; ZEZELL, DENISE M. . Characterization of ionizing radiation effects on bone using Fourier Transform Infrared Spectroscopy and multivariate analysis of spectra. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 22-27, 2017, Belo Horizonte, MG. Proceedings... Rio de Janeiro, RJ: Associação Brasileira de Energia Nuclear, 2017.

    Abstract: Ionizing radiation has been used as an important treatment and diagnostic method for several diseases. Optical techniques provides an efficient clinical diagnostic to support an accurate evaluation of the interaction of radiation with molecules. Fourier-transform infrared spectroscopy coupled with attenuated total reflectance (ATR-FTIR) is a label-free and nondestructive optical technique that can recognize functional groups in biological samples. In this work, 30 fragments of bone were collected from bovine femur diaphysis. Samples were cut and polished until 1 cm x 1 cm x 1 mm, which were then stored properly in the refrigerated environment. Samples irradiation was performed with a Cobalt-60 Gammacell Irradiator source at doses of 0.1 kGy, 1 kGy, whereas the fragments exposed to dose of 15 kGy was irradiated in a multipurpose irradiator of Cobalt-60. Spectral data was submitted to principal component analysis followed by linear discriminant analysis. Multivariate analysis was performed with Principal component analysis(PCA) followed by Linear Discriminant Analysis(LDA) using MATLAB R2015a software (The Mathworks Inc., Natick, MA, USA). We demonstrated the feasibility of using ATR-FTIR spectroscopy associated with PCA-LDA multivariate technique to evaluate the molecular changes in bone matrix caused by different doses: 0.1 kGy, 1 kGy and 15 kGy. These alterations between the groups are mainly reported in phosphate region. Our results open up new possibilities for protein monitoring relating to dose responses.

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  • IPEN-DOC 25532

    MILAGRE, MARIANA X. ; ARAUJO, JOAO V. de S. ; GOMES, MAURILIO P. ; DONATUS, UYIME ; MACHADO, CARULINE S.C. ; COSTA, ISOLDA . Comparison of the corrosion resistance of AA2024 and AA2098 alloys in different solutions. In: EUROPEAN CORROSION CONGRESS: APPLIED SCIENCE WITH CONSTANT AWARENESS, September 9-13, 2018, Krakow, Poland. Proceedings... Krakow: European Federation of Corrosion, 2018.

    Abstract: In this work the corrosion resistance of the AA2098-T351 and AA2024-T3 was evaluated and compared by electrochemical tests in 0.01 mol.L-1 of NaCl and 0.1 mol.L-1 of Na2SO4 with 0.001 mol.L-1 NaCl electrolytes. Monitoring of corrosion evolution in both alloys was carried out by electrochemical impedance spectroscopy (EIS) and polarization methods. The surface of the samples exposed to the test solutions was observed by microscopy after corrosion tests. The results showed different corrosion mechanisms in the two test solutions. In the sulfate containing electrolyte, the Al-Cu-Li alloy showed corrosion mechanism mainly associated with the micrometric particles at the surface, similarly to the AA2024-T3 alloy. However, in the chloride solution without sulfate, the AA2098-T351 alloy showed susceptibility to severe localized corrosion (SLC) besides the corrosion associated to the micrometric particles and the first type of corrosion was the main type of attack. The AA2024-T3 showed lower susceptibility to SLC than the AA2098- T351 alloy.

    Palavras-Chave: corrosion resistance; corrosion resistant alloys; monitoring; electrochemistry; polarization; aluminium alloys; lithium alloys; spectroscopy; copper alloys

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  • IPEN-DOC 26984

    ABREU, C.P. ; MELO, H.G. de; PEBERE, N.; MOGILI, N.V.V.; COSTA, I. ; VIVIER, V.. Corrosion resistance evaluation of the different zones on the AA2024-T3 and AA7475-T651 alloys welded by FSW. In: EUROPEAN CORROSION CONGRESS; INTERNATIONAL CORROSION CONGRESS, 20th; PROCESS SAFETY CONGRESS, September 3-7, 2017, Prague, Czech Republic. Proceedings... Frankfurt, Germany: European Federation of Corrosion, 2017. p. 1-14.

    Abstract: The aeronautic industry has a great interest in joining dissimilar aluminium alloys used in different parts of an aircraft. The Friction Stir Welding (FSW) process has been considered an effective alternative to conventional techniques for the welding of high strength alumin-ium alloys. However, this procedure results in zones with different microstructures due to thermal and thermomechanical effects involved during the joining process, leading to the formation of the thermomechanically affected zone (TMAZ), the heat affected zone (HAZ), the stir zone (nugget), and the unaffected base metal (BM). As the corrosion resistance of materials depends on their microstructures, the aim of this study was to investigate the intrin-sic corrosion resistance of the different zones of the AA2024-T3 and AA7475-T761 alloys welded by FSW, without considering the coupling effects between the different zones. This was achieved by evaluating the corrosion resistance of each individual zone in 0.1 M Na2SO4 + 1 mM NaCl solution by electrochemical techniques, such as open circuit potential meas-urements, polarization curves, and electrochemical impedance spectroscopy, using an elec-trochemical cell with an exposed area of 0.78 mm2. The electrochemical results showed that the lowest corrosion resistance was associated to the nugget zone, on which a galvanic cou-pling between the 2024 and 7475 alloys takes place. The corrosion resistance was also low-ered on the TMAZ of both alloys. This behaviour was associated to the enhanced precipita-tion of the η phase (MgZn2) at the grain boundaries in the 7475 alloy and to the coarsening of S phase (AlCuMg) precipitates in the 2024 alloy, both processes favoured by the thermome-chanical effects in these specific zones as demonstrated by TEM analysis.

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  • IPEN-DOC 26237

    ZAMATARO, CLAUDIA B. ; CARAMEL, AMANDA ; RABELO, THAIS F. ; KUCHAR, NIELSEN G. ; SOGLIA, VICTOR M.L.; ZEZELL, DENISE M. . Dental enamel submmitted to gamma radiation and ER,CR: YSGG laser associated to fluoride. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 1831-1843.

    Abstract: The in situ caries model can use bovine dental samples in human volunteers. Gamma radiation is a very efficient sterilization method that is not expected to alter the mineral content of the hard tissues, avoiding biases in the results. Samples (n=40) were irradiated through a source of 60Co multipurpose irradiator aiming complete sterilization (25 kGy/h) with the purpose of accumulating the native plaque on them at an in situ study. An Er,Cr:YSGG laser was used alone and in combination with the topical applications of: 1 dentifrice (1,100 μg F /g) or 2 APF (12,300 μg F--/g). Morphological and chemical analyses were performed by scanning electron microscopy (SEM), determination of alkali soluble fluoride concentration by specific ion electrode and surface microhardness determination. Then, the 15 volunteers used palatal devices containing previously treated samples and remained using F dentifrice. The effects of Fformation, on the reduction of demineralization were correlated. The biochemical analysis for quantification of alkaline soluble F determined the groups in which the laser was used after the topical application of the two types of fluoride products of different concentrations (dentifrice and APF) to be statistically different (p≤0.05), suggesting a prolonged effect of the synergy of the treatments in the reduction of the demineralization. Electronic Microscopy Scanning analysis has not shown thermal damage neither interprismatics changes from hydroxyapatite crystals, at dental enamel outside the buccal environment, after 25 kGy gamma irradiation, established that gamma radiation could be used aiming dental enamel sterilization.

    Palavras-Chave: cobalt 60; fluorine; gamma radiation; laser radiation; morphological changes; radiation doses; radiation effects; sterilization; teeth

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  • IPEN-DOC 26132

    PRIMO, CAMILA de O. ; ANGELOCCI, LUCAS V. ; KARAM JUNIOR, DIB; ZEITUNI, CARLOS A. ; ROSTELATO, MARIA E.C.M. . Dose-rate constant and air-kerma strength evaluation of a new 125-I brachytherapy source using Monte-Carlo. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 167-174.

    Abstract: Brachytherapy is a modality of radiotherapy which treats tumors using ionizing radiation with sources located close to the tumor. The sources can be produced from several radionuclides in various formats, such as Iodine-125 seeds and Iridium-192 wires. In order to produce a new Iodine-125 seed in IPEN/CNEN and ensure its quality, it is essential to describe the dosimetry of the seed, so when applied in a treatment the lowest possible dose to neighboring healthy tissues can be reached. The report by the AAPM’s Task Group 43 U1 is a document that indicates the dosimetry procedures in brachytherapy based on physical and geometrical parameters. In this study, dose-rate constant and air-kerma strength parameters were simulated using the Monte Carlo method radiation transport code MCNP4C. The air-kerma strength is obtained from an ideal modeled seed, since its actual value should be measured for seeds individually in a specialized lab with a Wide-Angle Free-Air Chamber (WAFAC). Dose-rate constant and air-kerma strength are parameters that depends on intrinsic characteristics of the source, i.e. geometry, radionuclide, encapsulation, and together they define the dose-rate to the reference point, defined as the dose-rate to a point 1 cm away from the geometric center of the source, in its transverse plane. This study presents the values found for these parameters with associated statistical uncertainty, and is part of a larger project that aims the full dosimetry of this new seed model, including experimental measures.

    Palavras-Chave: brachytherapy; computerized simulation; dose rates; dosimetry; iodine 125; kerma; monte carlo method

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  • IPEN-DOC 26539

    CASTRO, MAYSA C. de ; SILVA, NATALIA F. da ; CALDAS, LINDA V. E. . Dosimetric tests of an extrapolation chamber in standard computed tomography beams. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 116-120.

    Abstract: Computed tomography (CT) diagnostic exams are responsible for the highest dose values to the patients. Therefore, the radiation doses in this procedure must be accurate. For the dosimetry of CT beams, the radiation detector is usually a pencil-type ionization chamber. This type of dosimeter presents a uniform response to the incident radiation beam from all angles, which makes it suitable for such equipment since the X-ray tube executes a circular movement around the table during irradiation. However, there is no primary standard system for this kind of radiation beam yet. In order to search for a CT primary standard, an extrapolation chamber built at the Calibration Laboratory (LCI) of the Instituto de Pesquisas Energéticas e Nucleares (IPEN) was tested. An extrapolation chamber is a parallel-plate ionization chamber that allows the variation of its sensitive air volume. This chamber was used previously for low-energy radiation beams and showed results within the international recommended limits. The aim of this work is to perform some characterization tests (saturation curve, polarity effect, ion collection efficiency and linearity of response) considering the chamber depth of 1.25 mm in the radiation qualities for computed tomography beams at the LCI. The results showed to be within the international recommended limits.

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  • IPEN-DOC 26080

    BERECZKI, ALLAN ; WETTER, NIKLAUS U. ; CRUZ, FLAVIO C. da . Dynamically stable continuous single frequency green ring laser. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, October 7-9, 2019, São Paulo, SP. Proceedings... 2019.

    Abstract: A single-frequency ring laser using two standard commercial diode-pumped Nd:YAG modules is demonstrated. Employing a dynamically stable resonator design, multi-longitudinal mode operation at 1064 nm with 53 W of output power was obtained. When inserting a LBO crystal in the resonator, 1.8 W of single-sided, single-frequency output at 532 nm was achieved. The measured linewidth was 3.6 MHz, close to the resolution limit of the scanning etalon used to measure the longitudinal mode structure.

    Palavras-Chave: ring lasers; diode-pumped solid state lasers; neodymium lasers; yttrium compounds; resonators; lasers; frequency range; harmonic generation; harmonics; resonance

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  • IPEN-DOC 27331

    BERECZKI, A. ; WETTER, NIKLAUS U. . Dynamically stable lasers from commercial Nd:YAG modules with high beam quality and single-frequency: the correct choice of the fundamental waist size at the rod. In: KUDRYASHOV, ALEXIS V. (Ed.); PAXTON, ALAN H. (Ed.); ILCHENKO, VLADIMIR S. (Ed.); ARMANI, ANDREA M. (Ed.) SPIE PHOTONICS WEST; SPIE LASE, February 1-6, 2020, San Francisco, USA. Proceedings... Washington, USA: SPIE, 2020. p. 1126617-1 - 1126617-10. (Proceedings SPIE 11266, Laser Resonators, Microresonators, and Beam Control XXII). DOI: 10.1117/12.2545005

    Abstract: Diode-side pump Nd:YAG rod modules are widely available, reliable and commercially very attractive for building continuous-wave solid-state lasers in the 10-1000 W range. Newer technologies such as fiber or thin disk lasers are generally much more expensive but have the benefit of better beam quality and higher output powers if necessary. By using well-known techniques for designing dynamically stable resonators (DSRs), lasers with high extraction efficiency and high beam quality (fundamental mode, TEM00) can be obtained also with diode side-pumped modules. However, a successful project for a dynamic stable laser depends critically on the correct choice of the fundamental mode diameter within the rod. DSR design rules are based on the beam waist, w3, at the rod principal planes by considering the rod as a thin thermal lens, which differs significantly from real resonators. Here we give guidelines and criteria on how to establish the correct diameter in each case. Using off-the-shelf 75 W Nd:YAG modules it was possible to obtain linearly polarized TEM00-mode output of 30 W with M2=1.08 from a single module, M2=1.2 and 76.5 W of output power using two modules and 100.5 W of polarized, continuous output with M2=1.8. A single-frequency ring laser was also built, using two modules, generating 51.6 W of fundamental wave single-frequency output.

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