Navegação IPEN por ano de publicação "2020"

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  • IPEN-DOC 27585

    GONCALVES, KARINA de O.; VIEIRA, DANIEL P. ; LEVY, DEBORA; BYDLOWSKI, SERGIO P.; COURROL, LILIA C.. Uptake of silver, gold, and hybrids silver-iron, gold-iron and silver-gold aminolevulinic acid nanoparticles by MCF-7 breast cancer cells. Photodiagnosis and Photodynamic Therapy, v. 32, p. 1-10, 2020. DOI: 10.1016/j.pdpdt.2020.102080

    Abstract: Background. Nanoparticles show promise for theranostic applications in cancer. The metal-based nanoparticles can be used both as photosensitizers and delivery vehicles. In bimetallic particles based on gold or silver and iron, a combination of the plasmonic features of the gold or silver components with the magnetic properties of the iron makes these hybrid nanomaterials suitable for both imaging and therapeutic applications. Herein, we discuss toxicity and cell internalization of metallic (silver and gold) and bimetallic (silver-iron, gold-iron, and silver-gold) aminolevulinic acid (ALA) nanoparticles. ALA can control the production of an intracellular photosensitizer, protoporphyrin IX (PpIX), commonly used in photodynamic therapy. Methods. Nanoparticles were synthesized by photoreduction method and characterized by UV/Vis spectra, Zeta potential, FTIR, XRD, and transmission electron microscopy. The amount of singlet oxygen generation by a yellow LED, and ultrasound was studied for gold, gold-iron, and silver-gold nanoparticles. Cytotoxicity assays of MCF-7 in the presence of nanoparticles were performed, and PpIX fluorescence was quantified by high content screening (HCS). Results. Red fluorescence observed after 24 h of nanoparticles incubation on MCF-7 cells, indicated that the ALA in surface of nanoparticles was efficiently converted to PpIX. The best results for singlet oxygen generation with LED or ultrasound irradiation were obtained with ALA:AgAuNPs. Conclusions. The studied nanoparticles present the potential to deliver aminolevulinic acid to breast cancer cells efficiently, generate singlet oxygen, and convert ALA into PpIX inside the cells allowing photodiagnosis and therapies such as photodynamic and sonodynamic therapies.

    Palavras-Chave: gold; silver; nanoparticles; mammary glands; neoplasms; drug delivery; reduction; therapy; aminolevulinic acid

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  • IPEN-DOC 27592

    DIAZ, JULIO C.C.A. ; M'PEKO, JEAN-CLAUDE; VENET, MICHEL; SILVA JUNIOR, PAULO S. da. Unveiling the high‑temperature dielectric response of Bi0.5Na0.5TiO3. Scientific Reports, v. 10, n. 1, p. 1-11, 2020. DOI: 10.1038/s41598-020-75859-z

    Abstract: Understanding the physics behind changes in dielectric permittivity and mechanical response with temperature and frequency in lead-free ferroic materials is a fundamental key to achieve optimal properties and to guarantee good performance in the technological applications envisaged. In this work, dense Bi0.5Na0.5TiO3 (BNT) electroceramics were prepared through solid-state reaction of highgrade oxide reagents, followed by sintering at high temperature (1393 K for 3 h). In good agreement with previous reports in the literature, the thermal behaviour of dielectric response from these BNT materials showed the occurrence of a high-temperature diffuse-like permittivity peak, whose origin has been so far controversial. Thermally stimulated depolarization current, impedance and mechanical spectroscopies measurements were here conducted, over a wide range of temperature and frequency, to get a deep insight into the mechanism behind of this event. The approach included considering both as-sintered and reduced BNT samples, from which it is demonstrated that the broad high-temperature dielectric peak originates from interfacial polarization involving oxygen vacancies-related spacecharge effects that develop at the grain-to-grain contacts. This mechanism, that contributes to the anomalous behavior observed in the mechanical response at low frequencies, could also be responsible for the presence of ferroelastic domains up to high temperatures.

    Palavras-Chave: lead compounds; titanates; zirconium compounds; ceramics; thermal analysis; impedance

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  • IPEN-DOC 27358

    GROSSO, ROBSON L. ; VIKRANT, K.S.N.; FENG, LIN; MUCCILLO, ELIANA N.S. ; MUCHE, DERECK N.F.; JAWAHARRAM, GOWTHAM S.; BARR, CHRISTOPHER M.; MONTERROSA, ANTHONY M.; CASTRO, RICARDO H.R.; EDWIN GARCIA, R.; HATTAR, KHALID; DILLON, SHEN J.. Ultrahigh temperature in situ transmission electron microscopy based bicrystal coble creep in Zirconia II: interfacial thermodynamics and transport mechanisms. Acta Materialia, v. 200, p. 1008-1021, 2020. DOI: 10.1016/j.actamat.2020.08.070

    Abstract: This work uses a combination of stress dependent single grain boundary Coble creep and zero-creep ex- periments to measure interfacial energies, along with grain boundary point defect formation and migra- tion volumes in cubic ZrO 2 . These data, along with interfacial diffusivities measured in a companion paper are then applied to analyzing two-particle sintering. The analysis presented indicates that the large acti- vation volume, v ∗= v f + v m primarily derives from a large migration volume and suggests that the grain boundary rate limiting defects are delocalized, possibly due to electrostatic interactions between charge compensating defects. The discrete nature of the sintering and creep process observed in the small-scale experiments supports the hypothesis that grain boundary dislocations serve as sources and sinks for grain boundary point defects and facilitate strain during sintering and Coble creep. Model two-particle sintering experiments demonstrate that initial-stage densification follows interface reaction rate-limited kinetics.

    Palavras-Chave: grain boundaries; creep; transmission electron microscopy; temperature range 0400-1000 k; zirconium oxides; sintering; bicrystals; thermodynamics

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  • IPEN-DOC 27359

    VIKRANT, K.S.N.; GROSSO, ROBSON L. ; FENG, LIN; MUCCILLO, ELIANA N.S. ; MUCHE, DERECK N.F.; JAWAHARRAM, GOWTHAM S.; BARR, CHRISTOPHER M.; MONTERROSA, ANTHONY M.; CASTRO, RICARDO H.R.; EDWIN GARCIA, R.; HATTAR, KHALID; DILLON, SHEN J.. Ultrahigh temperature in situ transmission electron microscopy based bicrystal coble creep in zirconia I: nanowire growth and interfacial diffusivity. Acta Materialia, v. 199, p. 530-541, 2020. DOI: 10.1016/j.actamat.2020.08.069

    Abstract: This work demonstrates novel in situ transmission electron microscopy-based microscale single grain boundary Coble creep experiments used to grow nanowires through a solid-state process in cu- bic ZrO 2 between ≈1200 °C and ≈2100 °C. Experiments indicate Coble creep drives the for- mation of nanowires from asperity contacts during tensile displacement, which is confirmed by phase field simulations. The experiments also facilitate efficient measurement of grain boundary diffusivity and surface diffusivity. 10 mol% Sc 2 O 3 doped ZrO 2 is found to have a cation grain boundary diffusivity of D gb = ( 0 . 056 ±0 . 05 ) exp ( −380 , 0 0 0 ±41 , 0 0 0 RT ) m 2 s −1 , and surface diffusivity of D s = ( 0 . 10 ±0 . 27 ) exp ( −380 , 0 0 0 ±28 , 0 0 0 RT ) m 2 s −1 .

    Palavras-Chave: creep; temperature range 0400-1000 k; transmission electron microscopy; transmission; zirconium oxides; nanowires; grain boundaries

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  • IPEN-DOC 25565

    SERRA, PEDRO L.S.; MASOTTI, PAULO H.F. ; ROCHA, MARCELO S. ; ANDRADE, DELVONEI A. de ; TORRES, WALMIR M. ; MESQUITA, ROBERTO N. de . Two-phase flow void fraction estimation based on bubble image segmentation using Randomized Hough Transform with Neural Network (RHTN). Progress in Nuclear Energy, v. 118, p. 1-21, 2020. DOI: 10.1016/j.pnucene.2019.103133

    Abstract: The International Atomic Energy Agency (IAEA) has been encouraging the use of passive cooling systems in new designs of nuclear power plants. Next nuclear reactor generations are intended to have simpler and robust safety resources. Natural Circulation based systems hold an undoubtedly prominent position among these. The study of limiting conditions of these systems has led to instability behavior analysis where many different two-phase flow patterns are present. Void fraction is a key parameter in thermal transfer analysis of these flow instability conditions. This work presents a new method to estimate void fraction from images captured of an experimental two-phase flow circuit. The method integrates a set of Artificial Neural Networks with a modified Randomized Hough Transform to make multiple scans over acquired images, using crescent-sized masks. This method was called Randomized Hough Transform with Neural Network (RHTN). Each different mask size is chosen according with bubble sizes, which are the main ‘objects of interest’ in this image analysis. Images are segmented using fuzzy inference with different parameters adjusted based on acquisition focus. Void fraction calculation considers the volume of the imaged geometrical section of flow inside cylindrical glass tubes considering the acquisition depth-of-field used. The bubble volume is estimated based on geometrical parameters inferred for each detected bubble. The image database is obtained from experiments performed on a vertical two-phase flow circuit made of cylindrical glass where flow-patterns visualization is possible. The results have shown that the estimation method had good agreement with increasing void fraction experimental values. RHTN has been very efficient as bubble detector with very low ‘false-positive’ cases (< 0.004%) due robustness obtained through integration between Artificial Neural Networks with Randomized Hough Transforms.

    Palavras-Chave: two-phase flow; void fraction; neural networks; image processing; bubbles; fuzzy logic; transformations; nuclear power plants; pattern recognition; natural convection; randomness

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  • IPEN-DOC 26717

    MORAES, LETICIA P.R. ; MEI, JUN; FONSECA, FABIO C. ; SUN, ZIQI. Two-dimensional metal oxide nanomaterials for sustainable energy applications. In: ZAFEIRATOS, SPYRIDON (Ed.). 2D Nanomaterials for Energy Applications. Amsterdam, Netherlands: Elsevier, 2020. p. 39-72, cap. 2. DOI: 10.1016/B978-0-12-816723-6.00002-2

    Palavras-Chave: nanomaterials; metals; oxides; energy sources

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  • IPEN-DOC 27172

    ARAUJO, M.S. ; BARTOLOMÉ, J.F.; MELLO-CASTANHO, S. . Tribological and mechanical behaviour of 45S5 Bioglass®-based compositions containing alumina and strontium. Ceramics International, v. 46, n. 15, p. 24347-24354, 2020. DOI: 10.1016/j.ceramint.2020.06.216

    Abstract: Although bioactive glasses have been widely used for the surfaces of orthopaedic and dental implants, its limited mechanical strength, low toughness and wear resistance have prevented their use as load-bearing devices. Considering that even a small variation in the composition of such materials can deeply modify their features, inducing very different physicochemical or mechanical properties, the present research was conducted by modifying the glass network of 45S5 Bioglass® by adding Al2O3 and SrO to obtain a highly bioactive glass with improved mechanical and tribological performance for biomedical applications. The addition of 2% Al2O3 and 2% SrO produced a dense material with the same elastic modulus as 45S5 (~50 GPa). Moreover, the bending strength increased by 60% and the toughness doubled. The wear rate obtained against steel was found to be three times lower than that of 45S5. From the results, it can be assumed that both alumina and strontium synergistically play crucial roles in the mechanical and tribological properties of these new bioactive glasses.

    Palavras-Chave: glass; biological materials; silicates; strontium oxides; wear resistance; coefficient of performance; friction; mechanical properties

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  • IPEN-DOC 27122

    DAFRÉ-MARTINELLI, MARCELLE; FIGUEIREDO, ANA M.G. ; DOMINGOS, MARISA. Trace element leaf accumulation in native trees from the remaining Semideciduous Atlantic Forest in Brazil. Atmospheric Pollution Research, v. 11, n. 5, p. 871-879, 2020. DOI: 10.1016/j.apr.2020.01.015

    Abstract: Remnants of Semideciduous Atlantic Forest surrounded by numerous industries, intense road traffic and agricultural lands in Southeast Brazil have been affected by trace elements. We implemented a passive biomonitoring with the three most abundant native tree species (Astronium graveolens, Croton floribundus and Piptadenia gonoacantha) to answer these questions: 1) which species has the greatest potential to accumulate trace elements?; 2) does the leaf accumulation level of trace elements vary between the edge and interior of the forest remnants, between dry and wet periods or due to the distance from the industrial area?; 3) which species, among the most abundant in the forest remnants, would better indicate the spatial variations in trace elements pollution and which elements would be the most relevant for such spatial discrimination? Leaf samples were collected during the dry and wet seasons, at the edge and interior of four forest remnants. Trace elements were determined using inductively coupled plasma mass spectrometry (ICP MS). Few edge effects were evidenced in the leaf concentrations in all species. Higher concentrations of most trace elements were measured during dry season. Although C. floribundus showed the most accumulating capacity, A. graveolens was the most appropriate species to discriminate spatial variations. The forest closer to the industrial area was distinguished from the others by Mn and Ni from oil burning, but the metal pollution from the industrial area did not interfere on the leaf concentrations in A. graveolens sampled in the urban and rural forests.

    Palavras-Chave: air pollution; particulates; deposition; air pollution monitoring; biological indicators; trace amounts; elements; forests; brazil; trees; monitoring; leaves; environment; mass spectroscopy; plasma

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  • IPEN-DOC 26886

    GARCIA, VANESSA S.G. ; ROSA, JORGE M.; BORRELY, SUELI I. . Toxicity and color reduction of a textile effluent containing reactive red 239 dye by electron beam irradiation. Radiation Physics and Chemistry, v. 172, p. 1-5, 2020. DOI: 10.1016/j.radphyschem.2020.108765

    Abstract: Textile effluents are a mixture of dyestuff, surfactants, dispersants, acids, alkalis and bleaching agents, among other compounds, and some of these are highly soluble and relatively recalcitrant. Suitable improvement of textile effluents may require combined treatment processes, such as Conventional Treatments and Advanced Oxidative Process (AOPs). Electron beam irradiation (EBI) has been proposed as a possible technology for the treatment of textile effluents. In this context, the aim of the present study was to evaluate the efficiency of an Electron Beam treatment applied to toxicity and color reduction of a textile effluent containing reactive Red 239 dye. Effluent COD and TOC were also evaluated. The assessed effluents were submitted to EBI treatment at doses ranging from 0.5 to 15 kGy. Vibrio fischeri bacteria and Daphnia similis crustaceans were exposed to both irradiated and non-irradiated effluents, the toxicity was evaluated through EC50 (median effective concentration) calculations. EB irradiation successfully reduced effluent toxicity and color. The EC50 for D. similis(48h) were of 6.31% ± 3.19 (non-irradiated) and 27.56% ± 9.31 (10 kGy), and for V. fischeri(15min), of 7.41% ± 1.52 (nonirradiated) and 31.89% ± 10.99 (10 kGy), respectively. Approximately 70% toxicity reduction was obtained for both organisms, while 95% color reduction was obtained by applying 5 kGy.

    Palavras-Chave: toxicity; textiles; effluents; dyes; color; electron beams; textile industry; bacteria; crustaceans; experimental data; environmental impacts; toxic materials; decomposition

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  • IPEN-DOC 27183

    MAPRELIAN, EDUARDO ; TORRES, WALMIR M. ; BELCHIOR JUNIOR, ANTONIO ; UMBEHAUN, PEDRO E. ; BERRETTA, JOSE R. ; SABUNDJIAN, GAIANE . Total and partial loss of coolant experiments in an instrumented fuel assembly of IEA-R1 research reactor. Nuclear Engineering and Design, v. 363, p. 1-11, 2020. DOI: 10.1016/j.nucengdes.2020.110610

    Abstract: The safety of nuclear facilities has been a growing global concern, mainly after the Fukushima nuclear accident. Studies on nuclear research reactor accidents such as the Loss of Coolant Accident (LOCA), many times considered a design basis accident, are important for ensure the integrity of the plant. A LOCA may lead to the partial or complete uncovering of the fuel assemblies and it is necessary to assure the decay heat removal as a safety condition. This work aimed to perform, in a safe way, partial and complete uncovering experiments for an Instrumented Fuel Assembly (IFA), in order to measure and compare the actual fuel temperatures behavior for LOCA in similar conditions to research reactors. A test section for experimental simulation of Loss of Coolant Accident named STAR was designed and built. The IFA was irradiated in the IEA-R1 core and positioned in the STAR, which was totally immersed in the reactor pool. Thermocouples were installed in the IFA to measure the clad and fluid temperatures in several axial and radial positions. Experiments were carried out for five levels of uncovering of IFA, being one complete uncovering and four partial uncovering, in two different conditions of decay heat. It was observed that the cases of complete uncovering of the IFA were the most critical ones, that is, those cases presented higher clad temperatures when compared with partial uncovering cases, for the specific conditions of heat decay intensity and dissipation analyzed. The maximum temperatures reached in all experiments were quite below the fuel blister temperature, which is around 500 °C. The STAR has proven to be a safe and reliable experimental apparatus for conducting loss of coolant experiments.

    Palavras-Chave: computer codes; computerized simulation; data covariances; fuel assemblies; loss of coolant; natural convection; r codes; radiosensitivity effects; reactor accident simulation; research reactors; sensitivity analysis

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  • IPEN-DOC 27196

    JUNOT, DANILO O. ; SOUZA, DIVANIZIA N.; CALDAS, LINDA V.E. . TL/OSL signal of CaSO4:Eu,Ag samples produced by variations of the slow evaporation route. Radiation Measurements, v. 135, p. 1-8, 2020. DOI: 10.1016/j.radmeas.2020.106334

    Abstract: The aim of this work was to produce crystals of CaSO4 doped with europium (Eu) and silver (Ag) nanoparticles, by means of three different preparation routes, and to study their applicability in radiation dosimetry by the TL and OSL techniques. The crystals were produced by variations of the slow evaporation route. Samples of CaSO4: Eu,Ag(a) were obtained using europium oxide and silver particles as dopants. For the growth of the crystals of CaSO4:Eu,Ag(b), silver was incorporated in nitrate form. CaSO4:Eu,Ag(c) phosphorus were synthetized mixing europium oxide in a colloidal suspension of silver nanoparticles. Optical characterization confirmed the presence of Eu3þ/Eu2þ in the crystal matrix. Dosimetric characteristics were evaluated after the exposure of the samples to a90Sr/90Y source. The CaSO4:Eu,Ag(a) and CaSO4:Eu,Ag(b) composites presented the most intense signals, the lowest detectable doses, and showed a linear and reproducible dose response, but the CaSO4:Eu,Ag(a) samples showed the best potential for application in TL/OSL dosimetry.

    Palavras-Chave: thermoluminescence; photoluminescence; nanoparticles; dosimetry; radiation sources; synthesis; calcium sulfates; x-ray diffraction; dosemeters

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  • IPEN-DOC 27332

    BERECZKI, A. ; PAES, JOAO P.F. ; WETTER, NIKLAUS U. . Three-level Nd:YLF Raman laser directly pumped by a beam shaped diode bar. 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. 1126614-1 - 1126614-8. (Proceedings SPIE 11266, Laser Resonators, Microresonators, and Beam Control XXII). DOI: 10.1117/12.2544844

    Abstract: Low heat generation can be obtained when pumping Nd:YLF at wavelengths of 872 nm and 880 nm and emitting at the three-level transition of 908 nm. These transitions show very low quantum defect with efficiencies of 0.96 and 0.97, respectively. However, the low average absorption cross-section at these wavelengths makes efficient absorption even for longitudinal pump setups difficult. Using a beam-shaped pump diode instead of a fiber-coupled diode bar may be an effective means of increasing absorption because it can provide for π-polarized radiation which shows higher absorption cross section. In this work, a Nd:YLF was pumped at 872 nm by a diode bar using beam-shaping. Results were compared to pumping at 872 and 880 nm with non-polarized fiber-coupled diodes. Stimulated Raman scattering was also obtained with a KGW crystal generating first Stokes emissions at 990 nm and 976 nm.

    Palavras-Chave: laser radiation; raman spectra; neodymium lasers; yttrium; lithium; beam shaping; energy levels

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  • IPEN-DOC 27416

    FARIA, MARCELA E.M. ; LEITE, MARINA M.; ICHIKAWA, RODRIGO U. ; VICHI, FLAVIO M.; TURRILLAS, X. ; MARTINEZ, L.G. . Thickness estimation of TiO2-based nanotubes using X-ray diffraction techniques. Materials Science Forum, v. 1012, p. 179-184, 2020. DOI: 10.4028/www.scientific.net/MSF.1012.179

    Abstract: TiO2-based nanotubes are a very promising material with many applications in solar cells, biomedical devices, gas sensors, hydrogen generation, supercapacitors, and lithium batteries, among others. Nanotube thickness is a very important property since it is related to electronic and surface mechanics. In this sense, transmission electron microscopy (TEM) can be used. However, it can be difficult to acquire a good TEM image because the transversal section of the nanotubes needs to be visible. In this work, TiO2-based nanotubes obtained via hydrothermal synthesis were studied using X-ray line profile analysis. Scherrer and Single-Line methods provided consistent results for the thickness of the nanotubes (≃ 5 nm) when compared with TEM. Additionally, Single-Line method was also applied to estimate the microstrain. The advantage of using XRD is given by the fact that it is a quick and statistically significant analysis when compared with TEM. The results show that XRD can be used as a rapid and reliable alternative for the thickness estimation of nanotubes.

    Palavras-Chave: x-ray diffraction; titanium oxides; nanotubes; transmission electron microscopy; hydrothermal synthesis; thickness; equations

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  • IPEN-DOC 27233

    GONZALES-LORENZO, CARLOS D.; NASCIMENTO, LUANA F.; KODAIRA, SATOSHI; GOMES, MONISE B. ; WATANABE, SHIGUEO. Thermoluminescence studies of polycrystalline CaSiO3 pellets for photons and particle therapy beams. Radiation Physics and Chemistry, v. 177, p. 1-8, 2020. DOI: 10.1016/j.radphyschem.2020.109132

    Abstract: In this work, pellets of CaSiO3 have been produced for investigation as gamma radiation, proton, and carbon ions detector. They were then irradiated to gamma radiation using 137Cs and 60Co sources. Furthermore, pellets of CaSiO3 were exposed to 160 MeV proton and 290 MeV/n carbon ion beam from an upper synchrotron. Thermoluminescence (TL) responses of these pellets presented the same prominent peak at about 170 °C, and two possible high-temperature peaks at 270 and 320 °C when irradiated to gamma, proton, and carbon ion beam. Dose-response curve, minimum detectable dose (MDD), energy dependence, and dependence on the dose rate when irradiated with gamma radiation were evaluated in this material. Linear dose-response curves for proton and carbon ion irradiation have been compared to that of the gamma dose-response. In this way, the dose read out in Harshaw TL reader presented a good agreement with doses found using ion chamber in the case of proton beams and slightly less in the case of carbon beam due to the LET dependency. Furthermore, relative efficiencies of CaSiO3 for beam irradiation of proton and carbon ion display no dependence in the analyzed particle doses range.

    Palavras-Chave: thermoluminescence; calcium silicates; protons; carbon; dosimetry; particle beams; therapy; polycrystals; radiation detectors; gamma radiation; carbon ions

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  • IPEN-DOC 26520

    GONZALES-LORENZO, CARLOS D.; GUNDU RAO, T.K.; CANO, NILO F.; CARRERA, BETZABEL N.S. ; ROCCAB, RENE R.; CUEVAS-ARIZACA, EDY E.; AYALA-ARENAS, JORGE S.; WATANABE, SHIGUEO . Thermoluminescence and defect centers in β-CaSiO3 polycrystal. Journal of Luminescence, v. 217, p. 1-7, 2020. DOI: 10.1016/j.jlumin.2019.116783

    Abstract: β: CaSiO3 polycrystal was synthesized by the devitrification method. The polycrystal exhibits three thermoluminescence (TL) peaks at 124 ºC, 250 ºC and 306 ºC. Electron paramagnetic resonance (EPR) spectroscopy was used to study the defect centers induced in the polycrystal by gamma irradiation and to identify the centers responsible for the TL process. Three defect centers contribute to the observed spectrum at room temperature. Center I with principal g-values 2.0135, 2.0094 and 2.0038 is attributed to O ion and the center appears to be the recombination center for 124 ºC, 147 ºC and 306 C TL peaks. Center II exhibiting an isotropic g-value of 2.00025 is identified as an Fþ-center (singly ionized oxygen vacancy). Fþ-center is also observed to be a recombination center for several TL peaks. Center III is assigned to a Ti3þcenter displaying an orthorhombic g- tensor with principal values g1 ¼1.9830, g2 ¼1.9741 and g3 ¼1.9046. This center is associated with 124 ºC and 147 ºC TL peaks. TL emission spectrum of β-CaSiO3 shows two emission bands at 370 and 520 nm.

    Palavras-Chave: polycrystals; calcium oxides; calcium silicates; silicon oxides; crystal defects; thermoluminescence; epr spectrometers; electron spin resonance

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  • IPEN-DOC 27397

    PRADO, EDUARDO S.P.; MIRANDA, FELIPE S.; ARAUJO, LEANDRO G. de ; PETRACONI, GILBERTO; BALDAN, MAURICIO R.. Thermal plasma technology for radioactive waste treatment: a review. Journal of Radioanalytical and Nuclear Chemistry, v. 325, n. 2, p. 331-342, 2020. DOI: 10.1007/s10967-020-07269-4

    Abstract: In this paper, a review of radioactive wastes treatment using thermal plasma technology is presented as a treatment method for radioactive waste management.Virtually all waste streams can be treated by the thermal plasma technologies, resulting in a conditioned product, free from organics and liquids, definitely meeting the acceptance criteria for safe storage and disposal. The application of the thermal plasma system in the nuclear area is still one of the current research topics due to the theoretical and practical complexity of the treatment. This paper discusses the performance of the thermal plasma systems, addressing the advantages and limitations of the method.

    Palavras-Chave: plasma technology; radioactive waste management; radioactive waste processing; management; processing

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  • IPEN-DOC 27241

    SILVA FILHO, J.C.; VENANCIO, E.C.; SILVA, S.C. ; TAKIISHI, H. ; MARTINEZ, L.G. ; ANTUNES, R.A.. A thermal method for obtention of 2 to 3 reduced graphene oxide layers from graphene oxide. SN Applied Sciences, v. 2, n. 8, 2020. DOI: 10.1007/s42452-020-03241-9

    Abstract: In this work, a thermal reduction method was developed to obtain reduced graphene oxide (rGO) with 2 or 3 layers from graphene oxide (GO). The GO X-ray diffraction (XRD) patterns presented diffraction peak at 2θ = 10°, which is related to (002) reflection. After heat treatment under nitrogen ( N2(g)) atmosphere, this peak was shifted to 2θ = 25°, presenting an interlayer distance of 3.8 Å, associated to GO reduction. BET analysis of modified GO samples identified an average pore diameter of 45.38 Å and surface area of 23.06 m2/g. In the case of rGO1, rGO2 and rGO3 samples, they presented surface areas from 32.47 to 612.74 m2/g and an average pore diameter of 108.21–149.54 m2/g. Thermogravimetric analysis (TGA) indicated a higher mass loss between 150 and 230 °C. Raman spectra showed ID/IG ratios of rGO samples were higher than GO (1.36-GO; 1.45-rGO1, 1.87-rGO3) due to reducing GO and increasing sp2 clusters. XPS analysis revealed that the main carbon species in the samples were sp2- type bonds (14.99 at% for the GO and 47.85 at% for rGO3). The FTIR spectra of rGO1, rGO2 and rGO3 samples presented peaks at 3454.22 cm−1 (hydroxyl) and 1077.43 cm−1 (C–O).

    Palavras-Chave: oxides; graphene; thermal conductivity; layers; graphite; thermal gravimetric analysis; raman spectra

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  • IPEN-DOC 26441

    CARDOSO JUNIOR, MARCIO; CHEMALE JUNIOR, FARID; OLIVEIRA, CHRISTIE H.E. de; CRUZ, CARLOS E. de S.; ABREU, CARLOS J. de; GENEZINI, FREDERICO A. . Thermal history of potential gas reservoir rocks in the eastern Parnaíba Basin, Brazil. AAPG Bulletin, v. 104, n. 2, p. 305-328, 2020. DOI: 10.1306/05021918117

    Abstract: The Parnaíba Basin is a major intracratonic sedimentary basin in Brazil with unconventional petroleum systems as a potential natural resource formed by the influence of igneous intrusions. To constrain the thermal history of unexplored potential reservoir rocks in the eastern part of the Parnaíba Basin, sedimentary rocks near intrusions were analyzed by petrography and thermochronology (apatite fission-track [AFT] and zircon fission-track [ZFT] dating). Petrography shows grain dissolution and carbonate pore filling generated by thermal destabilization of feldspars. The AFT results indicate partial annealing by the last magmatic event in the basin, and ZFT results show ages of maximum paleotemperature compatible with the Sardinha magmatic event (120–130 Ma). In thermal history models, rocks close to intrusions experienced maximum paleotemperatures above 300°C, which is higher than what is considered favorable for reservoir rocks. Hydrothermal fluids modified the diagenetic evolution of the succession by dissolving and precipitating carbonate cement in pore spaces. In the studied area, at distances greater than 50m(>164 ft) from the intrusion, the rocks were not substantially altered, and in terms of paleotemperature, they can be considered potentially viable reservoirs. The thermal history analysis of potential tight gas sandstone reservoirs affected by intrusive bodies is valuable for characterizing the thermal enhancement or destruction of the reservoir’s qualities.

    Palavras-Chave: sedimentary basins; natural gas; reservoir rock; geologic deposits; petrography; sandstones; brazil; sedimentary rocks; petroleum geology

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  • IPEN-DOC 27232

    BICCA, MARCOS M.; KALKREUTH, WOLFGANG; SILVA, TAIS F. da; OLIVEIRA, CHRISTIE H.E. de; GENEZINI, FREDERICO A. . Thermal and depositional history of Early-Permian Rio Bonito Formation of southern Paraná Basin – Brazil. International Journal of Coal Geology, v. 228, p. 1-22, 2020. DOI: 10.1016/j.coal.2020.103554

    Abstract: The Paraná Basin is a large volcano-sedimentary basin with a complex depositional history from Ordovician to the Cretaceous period. During Permian significant amounts of organic-rich beds accumulated within the Rio Bonito and Irati formations representing deposition in coastal (deltaic and barrier lagoon) and shallow marine environments, respectively. In this work, the thermal history of these beds is examined from 16 vitrinite reflectance analyses of coal beds (Rio Bonito Formation), integrated with previous data on coal rank, and 21 apatite fission-track (AFT) analyses, collected from 17 well profiles in the south of the Paraná Basin. Coal samples showed three different maturity levels. Two with reflectances of 0.4–0.6 and 0.6–0.8%Rr formed by the natural burial history of the basin (the latter is restricted to the Torres Syncline area). In contrast, the third group reached much higher values (1.0–5.0%Rr) related to intrusive igneous rocks. The AFT data show thermal consistency with the reflectance values. The sandstone samples related to the two lower reflectance patterns were partially reset, preserving AFT ages older than the stratigraphic age of the bed. Otherwise, the samples severely affected by the magmatism have Cretaceous and Early Cenozoic ages, but some were much younger than the last magmatic event, implying deep burial before cooling onset. The mean track length distribution of the partially reset samples is short due to the inheritance of tracks preserved from basement cooling history. However, the population of fully reset samples gives crucial information on the maximum temperature reached and the age when cooling started. At these conditions, around 1.0 to 3.0 km of the Paraná Basin sequences would have been removed from the surface of the studied areas by erosion since Cretaceous. Regional variations in the amounts of removed sections were controlled by the structural framework, mostly regional NW-SE and NE-SW oriented structures.

    Palavras-Chave: sedimentary basins; geology; site characterization; coal deposits; cenozoic era; cretaceous period; magmatism; volcanic rocks; vitrinite; apatites; geologic history; deposits; underground disposal; brazil

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  • IPEN-DOC 27658

    GOMES, D.S. ; OLIVEIRA, F.B. . Thermal analysis of nuclear fuel using silicon carbide nanocomposite dispersion in UO2. In: PAN-AMERICAN NANOTECHNOLOGY CONFERENCE, 2nd, March 4-7, 2020, Águas de Lindoia, SP. Abstract... 2020.

    Abstract: After the Fukushima Daiichi disaster happened in Japan in 2011, it started a global effort to get more tolerant fuels. In 2019, the fleet of power reactors designated for electricity suppliers made up 451 power units, generating around 402 GWe. The nuclear power represents 11.2% of the electricity generated, avoiding about 1.2 GT of CO2. The civilian reactors are operating using the uranium dioxide (UO2) as the fuel, which shows poor thermal conductivity of 7.8 W/m-K at room temperature. The fuel temperatures can reach up until 1500 °C at regular operation. Silicon Carbide Nanotube (SiC-CNT) dispersed in the UO2 matrix containing 5 to 20% vol of SiC-CNTs permits to increases the thermal conductivity. The novel fuel concept improves the thermal conductivity of 30% with the addition of 5% of silicon carbide. The fuel pellet UO2-SiC/CNTs are sintered using Spark Plasma Sintering (SPS) with a hold time of 5 minutes, at 1300 °C, and a pressure of 40 MPa. The fuel mixture shows a better density, low porosity, and acceptable grain size distribution compared to traditional sintering routes. It simulated the fuel mixtures using fuel performance code FRAPCON adapted to the thermals and mechanic properties of compounds. This study showed the possibility of increasing the safety margins of nuclear fuel using the addition of a small fraction of nanocomposite.

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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.