Navegação Periódicos - Artigos por ano de publicação "2021"

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  • IPEN-DOC 27738

    SANTOS, DIOGO F. dos ; SANTOS, ADIMIR dos . Zero-power noise up to 100 kHz in the IPEN/MB-01 research reactor facility. Annals of Nuclear Energy, v. 152, p. 1-16, 2021. DOI: 10.1016/j.anucene.2020.107974

    Abstract: Subcritical noise experiments at frequencies up to 100 kHz employing two distinct boron dilution in the reactor tank water (286.8 and 578.6 ppm of natural boron) were performed in the IPEN/MB-01 reactor. The Auto Power Spectral Densities (APSD) were inferred employing the IPEN/MB-01 Correlator and were best described by a four-mode decay model up to about 70 kHz. The analyses reveal that the first two modes were related to thermal neutron and the other two to the fast ones. The coupling between thermal and fast neutrons was weak, and they could be considered uncoupled. A two-region two-group kinetic model was built and for the first time important parameters, such as the subcritical reactivities, generation times, and the prompt neutron decay constants all in the core and reflector in the 286.8 ppm case were inferred. The experiments can be considered unique of its kind and the theory/experiment comparisons reached good agreements.

    Palavras-Chave: zero power reactors; reactor noise; ipen-mb-1 reactor; spectral density; criticality; frequency measurement; lifetime; neutrons

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  • IPEN-DOC 27432

    ASFORA, VIVIANE K.; BUENO, CARMEN C. ; BARROS, VINICIUS M. de; KHOURY, HELEN; VAN GRIEKEN, RENE. X-ray spectrometry applied for characterization of bricks of Brazilian historical sites. X-Ray Spectrometry, v. 50, n. 1, p. 45-52, 2021. DOI: 10.1002/xrs.3194

    Abstract: This paper presents the results of X-ray fluorescence (XRF) analysis of bricks sampled from historical places in Pernambuco, a state in the northeastern region of Brazil. In this study, twenty bricks found in historical sites were analyzed. Two bricks made in the 17th century, presumably used as ballast in ships coming from Holland, five locally manufactured bricks: one from 18th century, three from 19th century, and one from 20th century, and thirteen bricks collected from a recent Archeological investigation of Alto da Sé, in the town of Olinda. Qualitative determination of the chemical elements present in the samples was undertaken using a self-assembled portable XRF system based on a compact X-ray tube and a thermoelectrically cooled Si-PIN photodiode system, both commercially available. X-ray diffraction analysis was also carried out to assess the crystalline mineral phases present in the bricks. The results showed that quartz (SiO2) is the major mineral content in all bricks. Although less expressive in the XRD patterns, mineral phases of illite, kaolinite, anorthite, and rutile are also identified. The trace element distribution patterns of the bricks, determined by the XRF technique, is dominated by Fe and, in decreasing order, by K, Ti, Ca, Mn, Zr, Rb, Sr, Cr, and Y with slight differences among them. Analyses of the chemical compositional features of the bricks, evaluated by principal component analysis of the XRF datasets, allowed the samples to be grouped into five clusters with similar chemical composition. These cluster groups were able to identify both age and manufacturing sites. Dutch bricks prepared with different geological clays compositions were defined.

    Palavras-Chave: archaeology; archaeological sites; building materials; bricks; manufacturing; construction; x-ray fluorescence analysis

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  • IPEN-DOC 27781

    DARIN, GASPAR ; IMAKUMA, KENGO ; SANTIAGO, RAFAEL T.; SILVA, KLEBSON L. da; COTICA, LUIZ F.; FABIAN, MARTIN; VALICEK, JAN; HAHN, HORST; SEPELAK, VLADIMIR. X-ray diffraction and thermoanalytical datasets of precursors of the Gd6UO12-δ phase processed by combined mechanochemical: thermal routes. Data in Brief, v. 35, p. 1-5, 2021. DOI: 10.1016/j.dib.2021.106972

    Abstract: The datasets presented here are related to the research paper entitled “Disordered Gd6UO12-δ with the cation antisite defects prepared by a combined mechanochemical−thermal method” [1]. The datasets complement the findings [1] on the effect of the combined mechanochemical−thermal processing of the stoichiometric mixture of solid precursors (3Gd2O3 + UO2) on the formation of Gd6UO12-δ phase. In this article, we provide (i) X-ray diffraction (XRD) data of the 3Gd2O3 + UO2 mixture milled for 12 h, (ii) the refined XRD data of the non-milled 3Gd2O3 + UO2 mixture after annealing at 1282 °C for 3 h in air, and (iii) the thermogravimetric and differential thermal analysis (TG-DTA) data for non-milled and mechanically preactivated 3Gd2O3 + UO2 mixture measured in air at a heat rate of 10 K/min.

    Palavras-Chave: gadolinium oxides; x-ray diffraction; datasets; thermal analysis

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  • IPEN-DOC 27818

    TANGTHONG, THEERANAN; PIROONPAN, THANANCHAI; THIPE, VELAPHI C. ; KHOOBCHANDANI, MENKA; KATTI, KAVITA; KATTI, KATTESH V.; PASANPHAN, WANVIMOL. Water-soluble chitosan conjugated DOTA-bombesin peptide capped gold nanoparticles as a targeted therapeutic agent for prostate cancer. Nanotechnology, Science and Applications, v. 14, p. 69-89, 2021. DOI: 10.2147/NSA.S301942

    Abstract: Introduction: Functionalization of water-soluble chitosan (WSCS) nanocolloids with, gold nanoparticles (AuNPs), and LyslLys3 (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-bombesin 1– 14 (DOTA-BBN) peptide affords an innovative pathway to produce prostate tumor cell-specific nanomedicine agents with potential applications in molecular imaging and therapy. Methods: The preparation involves the production and full characterization of water-soluble chitosan (WSCS), via gamma (γ) rays (80 kGy) irradiation, followed by DOTA-BBN conjugation for subsequent use as an effective template toward the synthesis of tumor cell-specific AuNPs-WSCS-DOTA-BBN. Results: The WSCS-DOTA-BBN polymeric nanoparticles (86 ± 2.03 nm) served multiple roles as reducing and stabilizing agents in the overall template synthesis of tumor cell-targeted AuNPs. The AuNPs capped with WSCS and WSCS-DOTA-BBN exhibited average Au-core diameter of 17 ± 8 nm and 20 ± 7 nm with hydrodynamic diameters of 56 ± 1 and 67± 2 nm, respectively. The AuNPs-WSCS-DOTA-BBN showed optimum in vitro stability in biologically relevant solutions. The targeted AuNPs showed selective affinity toward GRP receptors overexpressed in prostate cancer cells (PC-3 and LNCaP). Discussion: The AuNPs-WSCS-DOTA-BBN displayed cytotoxicity effects against PC-3 and LNCaP cancer cells, with concomitant safety toward the HAECs normal cells. The AuNPs-WSCS-DOTA-BBN showed synergistic targeting toward tumor cells with selective cytotoxicity of AuNPs towards PC-3 and LNCaP cells. Our investigations provide compelling evidence that AuNPs functionalized with WSCS-DOTA-BBN is an innovative nanomedicine approach for use in molecular imaging and therapy of GRP receptor-positive tumors. The template synthesis of AuNPs-WSCS-DOTA-BBN serves as an excellent non-radioactive surrogate for the development of the corresponding 198AuNPs theragnostic nanoradiopharmaceutical for use in cancer diagnosis and therapy.

    Palavras-Chave: nanoparticles; gold; prostate; neoplasms; radiopharmaceuticals; therapy; aqueous solutions; chitin

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  • IPEN-DOC 28159

    PEREZ, WILLIAM F.; BARBAN, MARILIA; ALMEIDA, JOAO H. de; BIANCHI, PAULO H. ; NASSER, BEATRIZ Z.B. de M.; AGUIAR, ELLEN M.R. de; ARENA, RAQUEL A.; ARAUJO, JADE de. Utilizando o IRAP para medir a transformação de função de estímulos relacionados à expressões faciais de medo ou de alegria: uma replicação sistemática / Using the IRAP to assess the transformation of function of stimuli related to facial expressions of fear or of happiness: A systematic replication. Perspectivas em Análise do Comportamento, v. 12, n. 1, p. 265-274, 2021. DOI: 10.18761/PAC.2021.v12.RFT.17

    Abstract: O presente estudo teve por objetivo replicar sistematicamente Perez et al. (2019) buscando avaliar a sensibilidade do IRAP à transformação de função dos estímulos em “condições mínimas”, isso é, partindo de um treino relacional com um baixo critério de acerto e na ausência de testes de derivação. Os participantes foram submetidos a um treino relacional que buscou estabelecer relações de coordenação (ou equivalência) entre faces expressando emoção (A1 [medo]; A2 [alegria]) e símbolos sem sentido (B1, B2, C1 e C2). Inicialmente, foram ensinadas as relações AB (A1B1 e A2B2), seguidas das relações BC (B1C1 e B2C2). O critério de acerto para progressão no treino era de 12 respostas corretas consecutivas. Na sequência, a transformação de função (ou do significado) dos estímulos C1 (=medo) e C2 (=alegria) foi avaliada por meio do IRAP. Os resultados sugerem a pronta transformação de significado dos estímulos Cs (C1 e C2) em acordo com as relações arbitrárias envolvidas no treino relacional. Assim, conclui-se que o IRAP é capaz de documentar a transformação de função a partir de relações convencionadas no contexto experimental mesmo quando o participante é exposto a um treino relacional como poucas tentativas e na ausência dos tradicionais testes de emergência ou derivação de novas relações.

    Palavras-Chave: behavior; human factors; programming; human populations; sociology

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  • IPEN-DOC 27893

    SILVA, T.T. ; BORRELY, S.I. . Use of ionizing radiation for the inhibition and removal of cyanotoxins in water: a brief review. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-18, 2021. DOI: 10.15392/bjrs.v9i1A.1457

    Abstract: Cyanobacteria are an ancient and diverse group of microorganisms, considered as important contributors to the formation of Earth's atmosphere and nitrogen fixation. However, the input of nutrients in water by anthropogenic activities frequently provides cyanobacteria blooms associated with toxic compounds. Secondary metabolites, also called cyanotoxins, are often harmful to wild and domestic life, including humans. The first part of this review focuses on cyanobacteria and their ability to produce a variety of toxins as well as describe the Brazilian guidelines on the evaluation and management of these toxins in water quality. Then, we present a review of recent literature on the use of ionizing radiation in terms of cyanobacteria cell removal, degree of degradation of cyanotoxins in water, and reaction kinetics. In view of the exposed results, the paper concludes that ionizing radiation is an efficient and economically viable alternative for the remediation of areas contaminated by cyanobacterial blooms and cyanotoxins, especially in reservoirs intended for water treatment and supply. In addition, some suggestions are provided for further studies on the use of this technology in the treatment of drinking water.

    Palavras-Chave: comparative evaluations; cyanobacteria; drinking water; electron beams; gamma radiation; inhibition; radiation doses; removal; toxins; water treatment

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  • IPEN-DOC 27829

    SILVA, REJANE M.P. da ; IZQUIERDO, JAVIER; MILAGRE, MARIANA X. ; BETANCOR-ABREU, ABENCHARA M.; COSTA, ISOLDA ; SOUTO, RICARDO M.. Use of amperometric and potentiometric probes in scanning electrochemical microscopy for the spatially-resolved monitoring of severe localized corrosion sites on aluminum alloy 2098-T351. Sensors, v. 21, n. 4, p. 1-15, 2021. DOI: 10.3390/s21041132

    Abstract: Amperometric and potentiometric probes were employed for the detection and characterization of reactive sites on the 2098-T351 Al-alloy (AA2098-T351) using scanning electrochemical microscopy (SECM). Firstly, the probe of concept was performed on a model Mg-Al galvanic pair system using SECM in the amperometric and potentiometric operation modes, in order to address the responsiveness of the probes for the characterization of this galvanic pair system. Next, these sensing probes were employed to characterize the 2098-T351 alloy surface immersed in a saline aqueous solution at ambient temperature. The distribution of reactive sites and the local pH changes associated with severe localized corrosion (SLC) on the alloy surface were imaged and subsequently studied. Higher hydrogen evolution, lower oxygen depletion and acidification occurred at the SLC sites developed on the 2098-T351 Al-alloy.

    Palavras-Chave: aluminium alloys; corrosion; electrochemical corrosion; amperometry; probes; measuring instruments

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  • IPEN-DOC 27774

    NORY, RENATA M. ; FIGUEIREDO, ANA M.G. ; SOUTO-OLIVEIRA, CARLOS E.; BABINSKI, MARLY. Urban contamination sources in tunnel dusts from São Paulo city: elemental and isotopic characterization. Atmospheric Environment, v. 254, p. 1-14, 2021. DOI: 10.1016/j.atmosenv.2021.118188

    Abstract: Elemental and isotopic composition of tunnel dusts collected from Jânio Quadros (JQ) and Maria Maluf (MM) tunnels in São Paulo city were analyzed aiming to determine the potential sources of trace elements in these environments. Sampling was performed in the summer and winter of 2017. Elemental mass fractions were determined by Instrumental Neutron Activation Analysis (INAA) and Graphite Furnace Electrothermal Atomic Absorption Spectrometry (GF-AAS) for 28 elements. Isotopic signatures of Pb and Zn were determined by Thermal Ionization Mass Spectrometry (TIMS) and Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS), respectively. The mean mass fractions of elements, such as Pb, Cd, Zn, Sb and Cu, were in general similar to the reported in the literature, in studies that demonstrated urban contamination by potentially toxic elements. Statistics demonstrated significant differences in mass fractions between the tunnels for most analyzed elements. Results showed that rare earth elements, U and Th, mostly associated with geogenic sources, presented higher concentrations in MM tunnels, while elements frequently related to vehicular emissions (Sb, Zn, Ba, Cu and Pb) presented mean mass fraction values higher in JQ tunnel, pointing to a more important contamination in JQ tunnel. No significant differences in the mass fractions between campaigns were observed, evidencing that tunnels are not much affected by external weather conditions. Pb isotopic analysis presented 206Pb/207Pb ratios between 1.1715 and 1.1791 and 208Pb/206Pb ratios between 2.0889 and 2.0961, which pointed out to a vehicular signature, related to tailpipe emissions. On the other hand, Zn isotope data also suggested a vehicular signature, but mostly related to the wear of tires and brakes. Grain size distribution analysis showed that the smallest fractions of dust contained, on average, about 10% of particulate matter of aerodynamic diameter smaller than 10 μm, fractions highly inhalable, what may be a concern to human health. Enrichment factors (EFs) showed that Cr, Zn, Cu, Cd, Pb and Sb are the most enriched elements, in both tunnels, but higher EFs were found for JQ tunnel. Principal Component Analysis revealed a profile for a crustal source, marked by U, Th and rare earth elements, whereas vehicular sources were characterized mostly by Pb, Ti and V from gasoline/diesel combustion; Pb and Ti from road paints; Sb, Ba and Zn from brakes, and Zn from wear of steel and tires. These results indicate an important anthropic impact in the tunnels and that vehicular traffic is the main source of potentially toxic elements.

    Palavras-Chave: absorption spectroscopy; contamination; dusts; elements; icp mass spectroscopy; isotope ratio; neutron activation analysis; toxic materials; tunnels; urban areas; x-ray diffraction; x-ray fluorescence analysis

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  • IPEN-DOC 27702

    GUILHEN, SABINE N. ; ROVANI, SUZIMARA ; ARAUJO, LEANDRO G. de ; TENORIO, JORGE A.S.; MASEK, ONDREJ. Uranium removal from aqueous solution using macauba endocarp-derived biochar: effect of physical activation. Environmental Pollution, v. 272, p. 1-10, 2021. DOI: 10.1016/j.envpol.2020.116022

    Abstract: The main aim of this study was to evaluate options for addressing two pressing challenges related to environmental quality and circular economy stemming from wastage or underutilization of abundant biomass residue resources and contamination of water by industrial effluents. In this study we focused on residues (endocarp) from Macaúba palm (Acrocomia aculeata) used for oil production, its conversion to activated biochar, and its potential use in uranium (U) removal from aqueous solutions. Batch adsorption experiments showed a much higher uranyl ions (U(VI)) removal efficiency of activated biochar compared to untreated biochar. As a result of activation, an increase in removal efficiency from 80.5% (untreated biochar) to 99.2% (after activation) was observed for a 5 mg L 1 initial U(VI) concentration solution adjusted to pH 3 using a 10 g L 1 adsorbent dosage. The BET surface area increased from 0.83 to 643 m2 g 1 with activation. Surface topography of the activated biochar showed a very characteristic morphology with high porosity. Activation significantly affected chemical surface of the biochar. FTIR analysis indicated that U(VI) was removed by physisorption from the aqueous solution. The adsorbed U(VI) was detected by micro X-ray fluorescence technique. Adsorption isotherms were employed to represent the results of the U adsorption onto the activated biochar. An estimation of the best fit was performed by calculating different deviation equations, also called error functions. The Redlich-Peterson isotherm model was the most appropriate for fitting the experimental data, suggesting heterogeneity of adsorption sites with different affinities for uranium setting up as a hybrid adsorption. These results demonstrated that physical activation significantly increases the adsorption capacity of macauba endocarp-derived biochar for uranium in aqueous solutions, and therefore open up a potential new application for this type of waste-derived biochar.

    Palavras-Chave: aqueous solutions; vegetable oils; vegetables; coconuts; uranium; adsorption; chemical activation; activated carbon; charcoal

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  • IPEN-DOC 28367

    BIANCOLLI, ANA L.G. ; BARBOSA, ANDREY S. ; KODAMA, YASKO ; SOUZA JUNIOR, ROGERIO R. de; LANFREDI, ALEXANDRE J.C.; FONSECA, FABIO C. ; REY, JOSE F.Q.; SANTIAGO, ELISABETE I. . Unveiling the influence of radiation-induced grafting methods on the properties of polyethylene-based anion-exchange membranes for alkaline fuel cells. Journal of Power Sources, v. 512, p. 1-12, 2021. DOI: 10.1016/j.jpowsour.2021.230484

    Abstract: Anion-exchange membranes (AEM) are envisioned as the enabling materials for the widespread use of cost-effective and efficient polymeric fuel cells. Advancing the understanding of the effect of radiation-induced grafting (RIG) method on the final properties of AEMs is crucial to boost the performance of anion-exchange membrane fuel cells (AEMFCs). The present study provides a systematic investigation of the effect of RIG methods on physicochemical properties of LDPE-based AEMs with similar degree of grafting (DoG) and ion exchange capacity (IEC). Samples grafted by two methods − pre-irradiation (PIM) and simultaneous (SM) − have the same molecular structure, but distinct physicochemical properties due to markedly differences in the degree of crosslinking. Detailed characterization of AEMs showed that RIG method determines the mechanical properties, water transport, and the distribution of ionic groups, which have a direct impact on fuel cell performance and durability. The discussed results show that grafting step directly influences the internal structure and morphology. Controlling the synthesis parameters during RIG is a key feature to design AEMs with enhanced properties that lead to high AEMFC performance and stability.

    Palavras-Chave: ion exchange; anions; membranes; fuel cells; irradiation

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  • IPEN-DOC 28064

    FUNGARO, D.A. ; SILVA, P.S.C. ; IZIDORO, J.C. ; HOWER, J.C.. Trace elements in coal, coal combustion products and soil from coal-fired power plant area evaluated by neutron activation analysis. Journal of Physics and Chemistry Research, v. 3, n. 1, p. 1-7, 2021. DOI: 10.36266/JPCR/130

    Abstract: The concentrations of trace elements were determined in coal, fly ashes from baghouse and cyclone filter, and bottom ash from the Figueira thermal power plant (FPP) by a neutron activation analysis technique. Study of the enrichment factor indicated that coal ashes were moderately enriched for all elements, except for Zn that exhibits significant to very-high enrichment. The mobilization of elements was observed in the zeolite products obtained from the three coal ashes. With regards to the amount present in each type of ash, most of the elements were present at same level in zeolites, with the exception of As which exhibited much lower concentration. The trace element concentrations of two soil samples collected in the vicinity of the FPP was also investigated. The results indicate that the FPP contributes mainly to the Zr and Ba pollution in nearby soils, particularly Zr pollution.

    Palavras-Chave: coal; elements; ashes; zeolites; combustion; enrichment

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  • IPEN-DOC 27859

    MELO, C.G. ; ROSA, J.M. ; GARCIA, V.S.G. ; BORRELY, S.I. ; PEREIRA, M.C.C. . Toxicity and color reduction of reactive dyestuff RB 21 and surfactant submitted to electron beam irradiation. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-14, 2021. DOI: 10.15392/bjrs.v9i1A.1311

    Abstract: There is an unwelcome reaction between the coloring and the water during the dyeing procedure, a portion of the coloring agent is lost in the bathing and it will compose the final whole effluent. The high absorbance index is related to lost dyestuffs and they also contribute with the toxic effects to the aquatic biota. In addition, these effluents contain large quantity of surfactants applied during dyeing baths, which also contribute to the high toxicity in these samples. The objective of this study was to evaluate electron beam irradiation technology, applied in samples of the Color Index Reactive Blue 21 (RB 21) dyestuff and in samples of surfactant non-ionic and in order to reduce toxicity for both and for RB 21, color reduction. Among the objectives of the study there are the dyestuff exhaustion degree, and some physical-chemical parameters. The acute toxicity assays were carried with Daphnia similis microcrustacean and the results of the dyestuff solution were: the irradiated samples with concentration 0.61 g L-1 did not present significant results, the EC 50 (%) value was to 58.26 for irradiated sample with 2.5 kGy and EC 50 (%) 63.59 for sample irradiated with 5 kGy. The surfactant was more toxic than RB 21, with EC 50 (%) value at 0.42. The color reduction reached 63.30% for the sample of the lowest concentration of effluent. There was a reduction of pH during irradiation.

    Palavras-Chave: color; dyes; electron beams; irradiation; liquid wastes; ph value; reduction; surfactants; toxicity; water

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  • IPEN-DOC 28366

    CABRAL, FERNANDA V. ; SOUZA, TIAGO H. dos S.; SELLERA, FABIO P.; FONTES, ADRIANA; RIBEIRO, MARTHA S. . Towards effective cutaneous leishmaniasis treatment with light-based technologies. A systematic review and meta-analysis of preclinical studies. Journal of Photochemistry and Photobiology B: Biology, v. 221, p. 1-8, 2021. DOI: 10.1016/j.jphotobiol.2021.112236

    Abstract: Cutaneous leishmaniasis (CL) is a neglected disease that represents a serious global public health concern. We performed a systematic review with meta-analysis targeting the use of light-based therapies on CL in preclinical studies since they are essential to identify the benefits, challenges, and limitations of proposing new technologies to fight CL. We searched Pubmed and Web of Science to include original preclinical researches in English that used light-based technologies to fight CL. Inclusion criteria encompassed any animal model for CL induction, an untreated infected group as the comparator, reliable and consistent methodology to develop and treat CL, focus on an antimicrobial therapeutic approach, and data for lesion size and/or parasite load in the infection site. We identified eight eligible articles, and all of them used photodynamic therapy (PDT). For the meta-analysis, three studies were included regarding the parasite load in the infection site and four comprised the lesion size. No overall statistically significant differences were observed between untreated control and PDT groups for parasite load. Differently, PDT significantly reduced the lesion size regardless of the protocol used to treat CL (in mm, SMD: -1.90; 95% CI: −3.74 to −0.07, p = 0.04). This finding is particularly encouraging since CL promotes disfiguring lesions that profoundly affect the quality of life of patients. We conclude that PDT is a new promising technology able to be topically used against CL if applied in more than one session, making it a promising ally for the management of CL.

    Palavras-Chave: protozoa; antimicrobial agents; therapy; photosensitivity

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  • IPEN-DOC 27736

    SANTOS, S.C. ; RODRIGUES JUNIOR, O. ; CAMPOS, L.L. . Towards a new promising dosimetric material from formation of thulium-yttria nanoparticles with EPR response. Materials Chemistry and Physics, v. 259, p. 1-7, 2021. DOI: 10.1016/j.matchemphys.2020.124005

    Abstract: Advances toward new materials for dosimetry application is essential to enhance quality assurance and quality improvement practices based on radiation protection concept. Face to this challenge the present work reports an approach to produce thulium-yttria nanoparticles with electron paramagntic resonance response by an alternative hydrothermal synthesis based on a relative low temperature and pressure. Distinct compositions of thulium-yttria nanoparticles with up to 2 at.%Tm (at.%, atomic percentage) were prepared and characterized by XRD, SEM, PCS, and EPR. The proposed synthesis method followed by thermal treatment of the precursor powder at 1100 ◦C for 2 h provided thulium-yttria nanoparticles with rounded shape, cubic C-type structure, and mean particle size (d50) less than 160 nm. Among all compositions formed, thulium-yttria nanoparticles prepared with 0.1%Tm presented the most remarkable EPR response. The production of fine thulium-yttria nanoparticles with EPR response supply meaningful parameters to advance in the formation of new dosimetry materials based on rare earths.

    Palavras-Chave: dosimetry; thulium oxides; yttrium; nanoparticles; rare earths; electron paramagnetic resonance; ceramics

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  • IPEN-DOC 28423

    MERIZIO, L.G.; BONTURIM, E.; ICHIKAWA, R.U. ; SILVA, I.G.N.; TEIXEIRA, V.C.; RODRIGUES, L.C.V.; BRITO, H.F.. Toward an energy-efficient synthesis method to improve persistent luminescence of Sr2MgSi2O7:Eu2+,Dy3+ materials. Materialia, v. 20, p. 1-10, 2021. DOI: 10.1016/j.mtla.2021.101226

    Abstract: The synthesis of persistent luminescent materials usually requires a multi-step long time annealing at high temperatures (>1200°C) in a resistive oven, causing a huge energy consumption. Also, to achieve reduced oxidation states of emitter ions (e.g., Eu3+ → Eu2+ ), the H2(g) atmosphere is often used, which can be dangerous and increase the costs of the process. Therefore, the development of a quick and new single-step green strategy, using in-situ low-risk atmosphere (e.g., CO(g)) and a microwave-assisted solid-state (MASS) method has been encouraged. In this work, we present a single-step method to synthesize the compound Sr2MgSi2O7:Eu2+,Dy3+ using the MASS method and the results were compared with those prepared by a conventional ceramic method. The luminescent material was prepared in 25 min of synthesis using carbon as a microwave susceptor and CO(g) atmosphere source at the same time. A higher concentration of Eu2+ emitter was identified by XANES in the MASS method product, which has a significant effect on the luminescence efficiency, as well as an improvement in the optical properties, leading to an emission 100 times more intense. Furthermore, to understand the Eu3+ reduction process under CO(g) atmosphere, we present here the innovative results of in-situ XANES analysis for the Sr2MgSi2O7:Eu2+,Dy3+ material. Finally, the MASS method makes it possible to prepare the materials with less than 5% of the ceramic method's duration in time. The energy-saving and better-quality persistent luminescent properties obtained in the MASS method provide viable applications on anti-counterfeiting markers, solar cell sensitizers, and other luminescent technologies.

    Palavras-Chave: microwave radiation; synthesis; rare earths; solids; luminescence; annealing; synchrotron radiation

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  • IPEN-DOC 27865

    CHIERENTIN, G.S. ; TEIXEIRA, B.S. ; MASTRO, N.L. . Total phenolic compounds of irradiated chia seeds. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-9, 2021. DOI: 10.15392/bjrs.v9i1A.1331

    Abstract: Chia seeds (Salvia hispanica L.) is a good source of oil, protein, dietary fiber, minerals and polyphenolic compounds. In order to study the influence of the processing methods on the content of phenolic compounds, the objective of this work was to evaluate the effect of gamma radiation, doses 0 (control), 5, 10 and 20 kGy, on the total phenolic compounds extracted from chia seeds. Seeds were first defatted and extracts produced with proper solvents. Total phenolic content was determined according to Folin-Ciocalteu’s method and the extraction solvents applied were ethanol 100%, ethanol 70%, ethanol 50%, methanol 100%, methanol 70% and methanol 50%. When using ethanol 100%, ethanol 70 %, ethanol 50%, methanol 100% and methanol 70%, the extraction yield was independent of the absorbed dose. With methanol 50%, the irradiation process affected positively the total phenolic yield from of chia seeds. In general, the absorbed dose as well as the nature of the solvent affected the extraction yield, although in a limited manner.

    Palavras-Chave: antioxidants; cobalt 60; dose rates; food processing; gamma radiation; irradiation; radiation dose units; radiation effects; seeds

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  • IPEN-DOC 28420

    OLIVO-ARIAS, L.P.; ARAUJO, L.G. . Three-dimensional transient numerical simulation of the solid volume fraction of a fluidized bed: the role of three solution orders using a discretization scheme. Latin-American Journal of Physics Education, v. 15, n. 2, p. 2303-1 - 2303-10, 2021.

    Abstract: The FLUENT solver employed in the Computational Fluid Dynamics (CFD) has been extensively developed to extend its robustness and precision for a wide range of flow regimes. For that, the FLUENT solver has a numerical method in the pressure-based solver that has traditionally been used for incompressible and slightly compressible flows. The algorithm is based on the pressure that solves the equations in a segregated or decoupled mode. This algorithm has proven to be robust and versatile and has been used cooperatively with a wide range of physical models, including multiphase flows and conjugated heat transfer. However, there are applications in which the convergence rate of the segregated algorithm is not satisfactory, generally due to the need in these coupling scenarios between the continuity and momentum equations. The objective of this article is to validate the Eulerian model to determine the volumetric fractions of the solid phase fraction. For this, we used data from the literature and the PCSIMPLE algorithm (solver) at different orders of solution of the continuity, momentum, and turbulence equations. Also, we determined its efficiency in transient systems and how it would affect the results in the hydrodynamics of a three-phase fluidized bed reactor. The results were significant, thus representing the phenomenon of interaction between the liquid-solid and solid-gas phases.

    Palavras-Chave: hydrodynamic model; computerized simulation; computer calculations; dynamics; fluidized beds

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  • IPEN-DOC 28365

    PANESI, A.R.Q. ; SILVA, R.P. ; CUNHA, E.F. ; KORKISCHKO, I. ; SANTIAGO, E.I. . Three-dimensional CFD modeling of H2/O2 HT-PEMFC based on H3PO4-doped PBI membranes. Ionics, v. 27, n. 8, p. 3461-3475, 2021. DOI: 10.1007/s11581-021-04107-9

    Abstract: A complete non-isothermal model of a HT-PEMFC setup using a PBI/ H3PO4 membrane was developed, modeled, and solved using COMSOL Multiphysics. Polarization curves were simulated and compared to the corresponding experimental data. In this work, a serpentine flow field and an active area of 5 cm2 have been implemented in a computational fluid dynamics (CFD) application. The model predicts water vapor transport, mass concentration of H3PO4, temperature, and membrane current density distribution. In this model, the anode feed is pure hydrogen, and oxygen is introduced at the cathode side. The heat transfer model was coupled with the electrochemical and mass transport; a particular heating configuration is investigated for temperature distribution, emphasizing the membrane. The models showed consistency and were used to investigate the behavior of H3PO4 concentration and all transport characteristics. The concentration of phosphoric acid decreases with increasing temperature and relative humidity and the diffusive flux of water vapor increases with the decrease of the operating voltage. Two different configurations of inlet and outlet flow channels were analyzed and the results were compared.

    Palavras-Chave: fuel cells; phosphoric acid; fluid mechanics; efficiency; computer calculations; dynamics

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  • IPEN-DOC 28157

    POLO, IVON O. ; JUNOT, DANILO O. ; NICOLUCCI, PATRICIA; CALDAS, LINDA . Thermoluminescent response of CaSO4:Eu,Ag detectors in 90Sr/90Y beta radiation beam / Respuesta termoluminiscente de detectores de CaSO4:Eu, Ag en un haz de radiación beta de 90Sr/90Y. Nucleus, v. 68, p. 32-35, 2021.

    Abstract: The results of the thermoluminescent (TL) response of the CaSO4:Eu,Ag detectors in the 90Sr/90Y beams of the Beta Secondary Standard 2 system of the Calibration Laboratory of IPEN (LCI/IPEN) are presented. The thermoluminescent glow curves were obtained from doses between 30 mGy and 500 mGy. The detectors showed a good reproducibility of the thermoluminescent response. The calculated calibration factor was (1.166 ± 0.024) x10-3mGy/a.u. and the factor determined by linear fitting was (1.120 ± 0.014) x10-3mGy/a.u., showing a difference of only 3.9%. The lower limit of detection was (4.96 ± 0.06) mGy. The detectors presentedan appropriate sensitivity for 90Sr/90Y beta radiation. Preliminary results showed suitable dosimetric characteristics for the establishment of a transfer system for beta radiation dosimetry of 90Sr/90Y beams.

    Palavras-Chave: thermoluminescence; sensitivity; calcium sulfates; strontium 90; yttrium 90; thermoluminescent dosemeters; response functions

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  • IPEN-DOC 28173

    REIS, S.L. ; GROSSO, R.L. ; MUCCILLO, E.N.S. . Thermal and spectroscopic characterization of sol-gel-synthesized doped lanthanum gallate. Journal of Thermal Analysis and Calorimetry, v. 146, n. 4, p. 1561-1567, 2021. DOI: 10.1007/s10973-020-10113-2

    Abstract: In this study, a complex oxide solid solution consisting of lanthanum gallate with partial substitutions for strontium and magnesium (La0.9Sr0.1Ga0.8Mg0.2O2.85) was synthesized by the sol–gel route, aiming to obtain a sinter active powder and a final material that could be stoichiometrically controlled. The thermal behavior of the synthesized powder involves several steps of decomposition. The linear shrinkage of green compacts up to 1500 °C was 31%. The bulk conductivity of sintered specimens increases with sintering temperature up to 1400 °C. The stoichiometry was maintained for sintering temperatures up to 1450 °C. Elemental mapping obtained by energy-dispersive spectroscopy evidenced magnesium segregation at the grain boundaries. The overall results evidence the suitability of the synthesis method for preparing doped lanthanum gallate.

    Palavras-Chave: thermal gravimetric analysis; differential thermal analysis; lanthanum compounds; powders; synthesis

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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.

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