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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 28098

    RODRIGUES, FABRIZIO M.; SILVA, LARISSA S.N. da; ZEZELL, DENISE M. ; ANA, PATRICIA A.. Compositional changes promoted by Er,Cr:YSGG laser when used to inhibit dentin erosion. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, May 31 - June 2, 2021, Online. Proceedings... Piscataway, NJ, USA: IEEE, 2021. DOI: 10.1109/SBFOTONIOPC50774.2021.9461943

    Abstract: Lasers are used for preventing demineralization, but there are no studies that report the compositional changes on root dentin irradiated with Er,Cr:YSGG (2.78μm) laser in an erosive process. In this in vitro study, fifty dentin slabs were distributed in 5 groups to be treated with Er,Cr:YSGG laser associated or not with application of acidulated phosphate fluoride gel (APF-gel); then, a 10-days erosion regimen was conducted and the composition changes were monitored by Fourier transform infrared spectroscopy. The data suggest a synergistic effect between laser irradiation and APF-gel, with a greater preventive effect when APF-gel was applied after irradiation.

    Palavras-Chave: dentistry; erosion; lasers; laser radiation; fluorides; fourier transformation; infrared radiation

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  • IPEN-DOC 28896

    YOSHIKAWA, DANIEL S.; SANTOS, CELIA A.L.; MARTIN, RAMON V.; ALMEIDA, NEUSVALDO L. de; FARIA, RUBENS N. ; CARVALHO, MATHEUS A.; WENDHAUSEN, PAULO A.; LANDGRAF, FERNANDO J.. Corrosion behavior of NdFeB permanent magnet in two neutral environments. In: INTERNATIONAL CORROSION CONGRESS, 21st; INTERNATIONAL CORROSION MEETING, 8th, July 20-23, 2021, Online. Anais... Rio de Janeiro, RJ: Associação Brasileira de Corrosão - ABRACO, 2021.

    Abstract: The NdFeB uncoated magnets have been magnetically characterized by demagnetization curves and their corrosion behavior have been evaluated (nonmagnetized state) by accelerated, immersion and electrochemical corrosion tests. The hygrothermal corrosion resistance was evaluated by: high accelerated stress test (HAST) and bulk corrosion test (BCT). The immersion tests were performed in ultrapure water with or without addition of chloride ions. The electrochemical tests, open circuit potential (OPC) and electrochemical impedance spectroscopy (EIS) were carried out in two neutral solutions (NaCl and Na2SO4), and on the two distinct surfaces of cubic magnets, i.e. parallel and perpendicular (pole) to the crystallographic c-axis of aligned ferromagnetic grains. Both accelerated tests presented weight loss below 1.0 mg/cm2 (BCT grade A). The chloride ions additions in immersion tests caused differential aeration corrosion. The EIS tests carried out in NaCl solution were more aggressive than in Na2SO4 solution, and indicated a different corrosion behavior between the parallel and pole faces evidenced by the response of the Nyquist diagrams.

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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.

    Palavras-Chave: aluminium alloys; corrosion resistance; friction; welding; microstructure

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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 28203

    TAPPIZ, B. ; SILVA, P.S.C. ; CARVALHO, E.F. ; BOTIA, S.; LINHARES, H.M.S.M.D.; OSTERMANN, C.K. ; BUSTILLOS, O.V. . Determination of 238-U and 232-Th in soil samples collected near the Amazon Tall Tower Observatory, Brazilian Amazon. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, November 29 - December 2, 2021, Online. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2021.

    Palavras-Chave: concentration ratio; daughter products; natural radioactivity; neutron activation analysis; soils; thorium 232; uranium 238

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  • IPEN-DOC 28207

    LINHARES, H.M.S.M.D.; COSTA, I.D.; TAPPIZ, B. ; MORAIS, M.C.; SILVA, P.S.C. . Determination of trace elements of fish from the lower portion of Pomba river by neutron activation. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, November 29 - December 2, 2021, Online. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2021.

    Palavras-Chave: chemical effluents; elements; fishes; food; pollutants; rivers; trace amounts

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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.

    Palavras-Chave: neodymium lasers; yttrium compounds; resonators; diode-pumped solid state lasers

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  • IPEN-DOC 27061

    TERADA, M.; QUEIROZ, F.M.; COSTENARO, H.; OLIVIER, M.G.; COSTA, I. ; MELO, H.G. de. Effect of cerium (III) on the corrosion protection properties of the film formed on the AA2524-T3 alloy by hydrothermal treatments. In: EUROPEAN CORROSION CONGRESS, September 11-15, 2016, Montpellier, France. Proceedings... Frankfurt, Germany: European Federation of Corrosion, 2016. p. 1-9.

    Abstract: Many industries use chromium-based anodizing processes with a subsequent sealing post-treatment containing hexavalent chromium ions to protect Al alloys. However, this method of protection causes large environmental and health related problems. This has encouraged the search for new surface treatments for metals with the requirements of effective protection against corrosion and generation of non-toxic residues to the environment. Recent studies are pointing towards chromium free anodizing processes, specifically the tartaric-sulfuric acid (TSA) one, as a viable alternative. Besides, sealing treatments of the Al anodic layer in chromate solutions are another source of toxic residues and their replacement for environmentally friendly alternatives are also of great interest. Surface treatments with cerium ions are being largely studied for the corrosion protection of Al alloys due to their good anticorrosion properties associated to the lack of toxic residues generated. In this investigation, a hydrothermal treatment in aqueous solution with cerium ions has been proposed as a post-treatment for TSA anodizing, and its effects on the AA2524-T3 alloy corrosion resistance investigated. This alloy presents a chemical composition similar to the AA2024 but with lower and more controlled amounts of alloying elements. The sealing treatment was carried out by immersion in aqueous solutions with cerium ions at the boiling temperature. The effect of Ce on the characteristics of the surface film formed, such as morphology and corrosion resistance, was investigated by SEM and electrochemical impedance spectroscopy. The results were compared to those of sealing in boiling water. The results showed that the sealing treatment in solution with Ce(III) ions presented a less stable behavior than the sealing with only boiling water. However, the results of the EIS experiments showed recovery of the protective properties of the system, indicating that some self-healing properties must be imparted to the system.

    Palavras-Chave: aluminium alloys; cerium ions; sealing materials; surface treatments; sol-gel process; sulfuric acid

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  • IPEN-DOC 26236

    ZANINI, NATHALIA ; RABELO, THAIS F. ; ZAMATARO, CLAUDIA B. ; JUVINO, AMANDA C. ; KUCHAR, NIELSEN G. ; CASTRO, PEDRO A.A. de ; ANA, PATRICIA A. da; ZEZELL, DENISE M. . Effect of Er,Cr:YSSG laser on dental Veneers removal submitted to gamma radiation. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 1819-1830.

    Abstract: The search for aesthetical rehabilitive treatment such as porcelain veneers is increasing over the past years. After CEP-FOUSP approval, the present study investigated the debonding of 20 ceramic fragments of lithium disilicate(5x5x1 mm) from human dental enamel bond with Variolink ® N. The samples were splitted in two groups: control (without gamma irradiation) and treatment (gamma irradiation: GL). EDS and FTIR was performed on enamel in both groups, before and after treatment. After cementation of the ceramic fragments the control group was only irradiated with Er, Cr: YSGG laser (λ = 2.78 nm) to remove the fragments, whereas the GL was gamma irradiated with 0.07 kGy followed by laser irradiation Er, Cr: YSGG for removal of laminates.The laser parameters were previously determined as follows: 3.5 W. The gamma and laser (GL) group was exposed to gamma radiation and the erbium laser was applied in both groups to remove lithium disilicate laminates from human dental enamel. Thus, the load required to remove the laminates after simulation of the radiotherapy treatment in the human dental enamel was analyzed by mechanical assay. In this assay, the GL group presented higher loads for the removal of the laminates compared to the control group. This indicates that the gamma radiation induces a water radiolysis by modifying the hybrid layer of the adhesive cement and increases the bond between the enamel and the resin cement, which hinders the laser debonding of the laminates.

    Palavras-Chave: ceramics; enamels; gamma radiation; irradiation; laser radiation; lasers; lithium; radiolysis; teeth; therapy; x-ray spectroscopy

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  • IPEN-DOC 26767

    LOPES, MONICA S.; MOTA, CLAUDIA C.B.O.; PEREIRA, DAISA L. ; AMARAL, MARCELLO M.; ZEZELL, DENISE M. ; GOMES, ANDERSON S.L.. Effect of Nd:YAG laser and aluminum oxide sandblasting preconditioning on lingual enamel: brackets shear bond strength and morphological characterization. In: WOJTKOWSKI, MACIEJ (Ed.); BOPPART, STEPHEN A. (Ed.); OH, WANG-YUHL (Ed.) EUROPEAN CONFERENCES ON BIOMEDICAL OPTICS, June 23-27, 2019, Munich, Germany. Proceedings... Bellingham, WA, USA: SPIE, 2019. p. 1107822-1 - 1107822-3. (Proceedings of SPIE-OSA Vol. 11078, Optical Coherence Imaging Techniques and Imaging in Scattering Media III). DOI: 10.1117/12.2527030

    Abstract: It is known that Nd:YAG laser radiation on dental structure can increase enamel resistance to demineralization; however, few studies report its impact in orthodontics. This study aimed to verify the interaction of Nd:YAG laser and aluminum oxide sandblasting (Al2O3) as preconditioning treatment of lingual brackets bonding to quantify the shear bond strength (SBS) and to characterize the enamel after different surface preconditioning techniques. Thirty-five bovines’ incisors were divided in 5 groups (n=7), according to the preconditioning. All groups had the lingual brackets bonded with Transbond XT adhesive according to manufacturer’ protocol, and shear bonded after 72h. Samples were analyzed by Optical Coherence Tomography (OCT) and Scanning Eletronic Microscope (SEM) to verify enamel alterations. Optical attenuation coefficient (α) was measured before any preconditioning (T0) and after preconditioning surface (T1) for each group. Statistics analysis ANOVA-test was used, followed by Post Hoc Tukey for shear bond strength data, and Kruskal Wallis and post hoc Dunn test for α data. SEM and OCT qualitative analysis showed the melting effect with laser irradiation and enamel crystal surface disorganization with sandblasting in T1 and after shear bond. All groups were adequate for SBS and the statistical differences (p=0.0034) among groups showed better results for groups with techniques association (laser and Al2O3 used in this or in reverse order) and the highest SBS when laser was used after. The Al2O3 removes part of melting effect. The α had statistical difference (p= 0.0124) among groups, increasing with laser and Al2O3 isolated and decrease with techniques association.

    Palavras-Chave: tomography; coherent radiation; aluminium oxides; oral cavity; dentistry

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  • IPEN-DOC 25258

    CASTRO, MICHELE C.B. de ; COUTO, ANTONIO A. ; ALMEIDA, GISELE F.C. ; MASSI, MARCOS; LIMA, NELSON B. de ; SILVA SOBRINHO, ARGEMIRO da; CASTAGNET, MARIANO ; XAVIER, GLEICY L. ; OLIVEIRA, RENE R. . Effect of plasma nitriding on fatigue behavior of Ti-6Al-4V alloy. In: INTERNATIONAL CONFERENCE ON ADVANCED COMPUTATIONAL ENGINEERING AND EXPERIMENTING, 12th, July 1-5, 2018, Amsterdam. Proceedings... 2018. DOI: 10.20944/preprints201812.0326.v1

    Abstract: The Ti-6Al-4V alloy is widely used in the manufacture of components that should have low density, high corrosion resistance, and fatigue strength. The fatigue strength can be improved by surface modification. The aim of this study was to determine the influence of plasma nitriding on the fatigue behavior of Ti-6Al-4V alloy with a lamellar microstructure (Widmanstätten type). Nitriding was executed at 720 °C for 4 hours in an atmosphere with N2, Ar and H2. Samples microstructure characterization was carried out by X-ray diffraction analysis, optical microscopy and scanning electron microscopy. The average roughness of the specimens was determined, and fatigue tests were executed in a bending-rotating machine with reverse tension cycles (R= -1). X-ray diffraction analysis revealed the matrix phases α and β, and the phases Ɛ-Ti2N and δ-TiN in the nitrided alloy. A nitrogen diffusion layer was formed between the substrate and the titanium nitrides. Plasma nitriding resulted in an increase in low cycle fatigue strength, whereas at high cycles, both conditions exhibit similar behavior. The fracture surface of the fatigue tested specimens clearly revealed the lamellar microstructure. The fracture mechanism appears to be due to cracking at the interface of α and β phases of the lamellar microstructure.

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  • IPEN-DOC 26823

    MACHADO, CARULINE de S.C. ; SILVA, REJANE M. da ; ARAUJO, JOAO V. de S. ; DONATUS, UYIME ; MILAGRE, MARIANA X. ; KLUMPP, RAFAEL E. ; ROSSI, JESUALDO L. ; COSTA, ISOLDA . Effects of chloride ion concentration on the corrosion behavior of the AA2198-T8 alloy. In: EUROPEAN CORROSION CONGRESS, September 9-13, 2019, Seville, Spain. Proceedings... 2019.

    Abstract: In this work, the influence of chloride ions concentration on the corrosion behavior of the AA2198-T8 alloy was evaluated. Immersion test and electrochemical analyses were performed in sodium chloride solutions of three concentrations, 0.001 mol L-1, 0.005 mol L-1 and 0.01 mol L-1. The results showed that the AA2198-T8 alloy was susceptible to localized corrosion (LC) and to severe localized corrosion (SLC) in all conditions investigated. The electrochemical results obtained by open circuit potential measurements, cyclic voltammetry and potentiodynamic polarization curves were associated with the corroded microstructure of the alloy. Although electrochemical techniques allowed differentiating the corrosion resistance as a function of chloride concentration, the result was strongly influenced by the corroded/uncorroded area ratio related to the SLC.

    Palavras-Chave: aluminium alloys; corrosion; electrochemical corrosion; electrochemistry; chlorides

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  • IPEN-DOC 26205

    SILVA, NATALIA F. da ; SILVA, TIAGO F.; S. FILHO, LUCAS A.; CASTRO, MAYSA C. de ; LUZ, HUGO N. da; CALDAS, LINDA V. E. . Electrical characterization of the amplification plate of a thick-GEM detector for low energy X radiation dosimetry. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 1171-1175.

    Abstract: To evaluate the possible use of Thick-GEM detectors as dosimeters in standard mammography radiation qualities, a prototype is under development for tests. This is a collaboration project between the IPEN Calibration Laboratory and the High Energy Physics and Instrumentation Center (HEPIC-IFUSP). The prototype design takes into consideration many parameters that were obtained in an exploratory work using the Monte Carlo simulation code MCNP5. Using simulations, parameters such as typical dimensions and materials were optimized to match the characteristics of the detector to the requirements of a dosimeter for this purpose. At the present status of the project, electrical tests were undertaken to evaluate the quality of the amplification plate produced in-house. The amplification plate is composed of fiberglass with a thickness of 0.5 mm and 0.03 mm of copper on each side. The average diameter of the orifices in the plate is 0.25 mm, and the distance between centers is 1.00 mm. During the electrical tests, the amplification plate was in a gas chamber filled with Argon at atmospheric pressure. The leakage current was measured as a function of the applied voltage between the copper cladding of both sides. The electrical resistance of 15.3GΩ was obtained. Additionally, the breakdown voltage was observed at approximately 1.0 kV, limiting the maximum amplification voltages to this value.

    Palavras-Chave: amplification; argon; dosemeters; electric conductivity; electric potential; electrical testing; monte carlo method; plates; radiation detectors; x radiation

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  • IPEN-DOC 26136

    ANGELOCCI, LUCAS V. ; NOGUEIRA, BEATRIZ R. ; ABREU, RODRIGO T. ; ZEITUNI, CARLOS A. ; ROSTELATO, MARIA E.C.M. . End-weld thickness variation effects on dose rate for a new ir-192 brachytherapy source. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 198-206.

    Abstract: Brachytherapy is a form of radiation therapy that uses small sealed sources close to the tumor to deliver a high dose to target while keeping dose on neighboring healthy tissues as low as possible. A wide variety of radionuclides and different sources are available for brachytherapy, each with his own unique geometry. The Laboratory of Sources Production for Radiotherapy (IPEN/CNEN) developed a new Ir-192 seed for eye tumor treatment that is currently under dosimetric definition. This work is part of a larger project that aims the full dosimetry of this new source, but rather than calculate the usual parameters proposed by the American Association of Physicists in Medicine, the specific contribution to the dose rate of a usually not considered factor was investigated under a statistical approach: end-weld thickness variation, which is important due to this source being welded by an in-house method. Its effects were investigated using the Monte Carlo radiation transport code MCNP4C and an in-house routine programmed with MATLAB® to analyze the data. Final results are presented as a mean value for dose rate at different points of interest and their associated standard deviations. The results are discussed based on the influence of said parameter on different points around the source.

    Palavras-Chave: brachytherapy; dose rates; dosimetry; eyes; iridium 192; monte carlo method; radiation source implants; sealed sources; thickness; welding

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  • IPEN-DOC 27069

    PROVASI, C.; CASSIMIRO-SILVA, P.F.; ANA, P.A. da; ZEZELL, D.M. ; GOMES, A.S.L.; LINS, E.C.. Estudo da espectroscopia de reflexão com radiações visíveis e infravermelhas para discriminação de tecidos pulpares humanos sadios e patológicos. In: VIEIRA NETO, HUGO (Ed.); SOARES, ALCIMAR B. (Ed.); FÉLIX, RODRIGO P.B. da C. (Ed.); VIEIRA NETO, HUGO (Org.); MAIA, JOAQUIM M. (Org.); PICHORIM, SÉRGIO F. (Org.); GAMBA, HUMBERTO R. (Org.); COSTA, EDUARDO T. (Org.) CONGRESSO BRASILEIRO DE ENGENHARIA BIOMÉDICA, 25., 17-20 de outubro, 2016, Foz do Iguaçu, PR. Anais... Rio de Janeiro, RJ: Sociedade Brasileira de Engenharia Biomédica, 2016. p. 1909-1912.

    Abstract: A polpa dental é o tecido mais interno do dente. Sua principal função é garantir a dentinogênese e a sensibilidade dental, e por essa razão a informação clínica sobre a saúde da polpa é relevante. Polpas diagnosticadas como não-vitais são encaminhadas para um tratamento endodôntico agressivo, baseado na remoção de todo tecido degradado. Por esse motivo, deve-se haver um esforço em minimizar o número de falsos diagnósticos clínicos da vitalidade pulpar, na intenção de preservar a integridade do paciente. Esse estudo propõe a espectroscopia no visível e no infravermelho como método de melhorar a precisão no diagnóstico do status pulpar. Ele é baseado em confrontar a reflexão óptica dos tecidos no espectro do visível (VIS) e do infravermelho próximo (NIR) (350nm a 1.700nm) no intuito de discriminar polpas humanas vitais de outras polpas sintomáticas de pulpite. A Análise dos Componentes Principais (PCA) sobre os espectros de reflexão ainda propôs modelos matemáticos de diferenciação dos grupos. Os resultados revelaram que a reflexão óptica pode discriminar o status da vitalidade de polpas humanas vivas; e a análise estatística da PCA revelou precisão de acerto de 100% para radiações NIR e 95% para radiações VIS.

    Palavras-Chave: dentistry; teeth; visible radiation; infrared radiation; spectroscopy

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  • IPEN-DOC 28102

    VALLE, MATHEUS del ; SANTOS, MOISES O. dos ; SANTOS, SOFIA N. dos ; BERNARDES, EMERSON S. ; ZEZELL, DENISE M. . Evaluation of machine learning models for the classification of breast cancer hormone receptors using micro-FTIR images. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, May 31 - June 2, 2021, Online. Proceedings... Piscataway, NJ, USA: IEEE, 2021. DOI: 10.1109/SBFOTONIOPC50774.2021.9461946

    Abstract: The breast cancer is the most incident cancer in women. Evaluation of hormone receptors expression plays an important role to outline treatment strategies. FTIR spectroscopy imaging may be employed as an additional technique, providing extra information to help physicians. In this work, estrogen and progesterone receptors expression were evaluated using tumors biopsies from human cell lines inoculated in mice. FTIR images were collect from histological sections, and six machine learning models were applied and assessed. Xtreme gradient boost and Linear Discriminant Analysis presented the best accuracies results, indicating to be potential models for breast cancer classification tasks.

    Palavras-Chave: mammary glands; neoplasms; fourier transformation; images; machine learning; hormones; receptors

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  • IPEN-DOC 28103

    JUVINO, AMANDA C. ; ROMANO, MARIANA; ALVES, NATHALIA Z. ; FREITAS, THAIS R. ; ZAMATARO, CLAUDIA B. ; ZEZELL, DENISE M. . Evaluation of the anti-caries effect beyond the critical enamel pH of preventive treatment of fluoride associated with Nd:YAG laser irradiation. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, May 31 - June 2, 2021, Online. Proceedings... Piscataway, NJ, USA: IEEE, 2021. DOI: 10.1109/SBFotonIOPC50774.2021.9461860

    Abstract: This study aimed to evaluate the anti-caries effect of fluoride associated with Nd:YAG laser irradiation in the h-eatment of enamel Eight groups (n = S) were analyzed: Negative Control pH 4.5; Negative control pH 4; Fluoride pH 4.5; Fluoride pH 4; Nd-YAG pH 4.5; Nd-YAG pH 4; (Fluoride + Nd-YAG) pH 4.5 and (Fluoride + Nd-YAG) pH 4. All samples were analyzed by Scanning Electron Microscopy (SEM) before and after the cycle. Quantification of phosphorus in the cycling solutions was carried out using the colorimetric method, as an indication of enamel demineralization. The anti-caries effect of the Fluoride + Nd: YAG treatment in addition to the critical pH of the enamel can be observed in the morphological analysis, however in the analysis of the demineralization solutions, the amount of phosphorus showed a difference only in the Fluoiide group compared to the others in the investigative pH.

    Palavras-Chave: dentistry; fluorides; laser radiation; caries; neodymium lasers; ph value

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A pesquisa no RD utiliza os recursos de busca da maioria das bases de dados. No entanto algumas dicas podem auxiliar para obter um resultado mais pertinente.

✔ É possível efetuar a busca de um autor ou um termo em todo o RD, por meio do Buscar no Repositório , isto é, o termo solicitado será localizado em qualquer campo do RD. No entanto esse tipo de pesquisa não é recomendada a não ser que se deseje um resultado amplo e generalizado.

✔ A pesquisa apresentará melhor resultado selecionando um dos filtros disponíveis em Navegar

✔ Os filtros disponíveis em Navegar tais como: Coleções, Ano de publicação, Títulos, Assuntos, Autores, Revista, Tipo de publicação são autoexplicativos. O filtro, Autores IPEN apresenta uma relação com os autores vinculados ao IPEN; o ID Autor IPEN diz respeito ao número único de identificação de cada autor constante no RD e sob o qual estão agrupados todos os seus trabalhos independente das variáveis do seu nome; Tipo de acesso diz respeito à acessibilidade do documento, isto é , sujeito as leis de direitos autorais, ID RT apresenta a relação dos relatórios técnicos, restritos para consulta das comunidades indicadas.

A opção Busca avançada utiliza os conectores da lógica boleana, é o melhor recurso para combinar chaves de busca e obter documentos relevantes à sua pesquisa, utilize os filtros apresentados na caixa de seleção para refinar o resultado de busca. Pode-se adicionar vários filtros a uma mesma busca.

Exemplo:

Buscar os artigos apresentados em um evento internacional de 2015, sobre loss of coolant, do autor Maprelian.

Autor: Maprelian

Título: loss of coolant

Tipo de publicação: Texto completo de evento

Ano de publicação: 2015

✔ Para indexação dos documentos é utilizado o Thesaurus do INIS, especializado na área nuclear e utilizado em todos os países membros da International Atomic Energy Agency – IAEA , por esse motivo, utilize os termos de busca de assunto em inglês; isto não exclui a busca livre por palavras, apenas o resultado pode não ser tão relevante ou pertinente.

✔ 95% do RD apresenta o texto completo do documento com livre acesso, para aqueles que apresentam o significa que e o documento está sujeito as leis de direitos autorais, solicita-se nesses casos contatar a Biblioteca do IPEN, bibl@ipen.br .

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O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

1. Portaria IPEN-CNEN/SP nº 387, que estabeleceu os princípios que nortearam a criação do RDI, clique aqui.


2. A experiência do Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) na criação de um Repositório Digital Institucional – RDI, clique aqui.

O Repositório Digital do IPEN é um equipamento institucional de acesso aberto, criado com o objetivo de reunir, preservar, disponibilizar e conferir maior visibilidade à Produção Científica publicada pelo Instituto, desde sua criação em 1956.

Operando, inicialmente como uma base de dados referencial o Repositório foi disponibilizado na atual plataforma, em junho de 2015. No Repositório está disponível o acesso ao conteúdo digital de artigos de periódicos, eventos, nacionais e internacionais, livros, capítulos, dissertações, teses e relatórios técnicos.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.