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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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.

  • 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

  • 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

  • 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

  • IPEN-DOC 27713

    LIMA, VERA M.F. de ; PEREIRA JUNIOR, ALFREDO; OLIVEIRA, GUILHERME L. de. The spreading depression propagation: how electrochemical patterns distort or create perception. Open Journal of Biophysics, v. 11, n. 2, p. 133-146, 2021. DOI: 10.4236/ojbiphy.2021.112003

    Abstract: At the transition from quiescence to propagating waves recorded in isolated retinas, a circular electric current closes in the extracellular matrix; this circular current creates a magnetic torus flow that, when entering quiescent tissue in front of the wave, recruits elements and when leaving behind, helps to build the absolute refractory state. The waving magnetic torus is the consequence of the vortex effect and explains the energy boost that drives propagation. Methods: We interpret experimental results from intrinsic and extrinsic fluorescence dyes, voltage, calcium and pH sensitive, optical signals from isolated retinas, and time series recordings using ion exchange resins: Ca, K, pH, Na, Cl recorded extracellularly at retinas, cerebellums and cortices coupled to spreading depression waves. Finally, we checked the ECoG activity, also a time series, at the transition from after discharges to spreading depression in rat hippocampus. Results: The integrated assessment of the diversified measurements led to the realization that the magnetic flow at the wavefront is a major contributor to the wave propagation mechanisms. This flow couples mass and charge flows as a swirling torus from excited to quiescent tissue. Conclusions: An alternative model of the brain is possible, apart from the classical HH and molecular biology model. Physical chemistry of charged gels and its flows explains the results. The conceptual framework uses far from equilibrium thermodynamics.

    Palavras-Chave: brain; electrochemistry; retina; resonance; central nervous system; vortices; vortex flow

  • IPEN-DOC 27544

    SILVA, A.A.A. da; STEIL, M.C.; TABUTI, F.N. ; RABELO-NETO, R.C.; NORONHA, F.B.; MATTOS, L.V.; FONSECA, F.C. . The role of the ceria dopant on Ni / doped-ceria anodic layer cermets for direct ethanol solid oxide fuel cell. International Journal of Hydrogen Energy, v. 46, n. 5, p. 4309-4328, 2021. DOI: 10.1016/j.ijhydene.2020.10.155

    Abstract: The effect of ceria dopant aiming at stability in Ni/doped-ceria anodic layers for direct ethanol solid oxide fuel cells (SOFC) was studied. Solid solutions of ceria doped with Y, Gd, Zr, or Nb (10 mol%) impregnated with NiO were tested in a fixed bed reactor for ethanol conversion reactions and for direct (dry) ethanol SOFC. The ceria dopant showed a marked effect on both the catalytic and the electrical transport properties of the ceramic support. Catalytic activity data revealed that the studied materials deactivate in ethanol decomposition reaction but are stable for ethanol steam reforming. Thus, feeding dry ethanol to the SOFC with a Ni/doped-ceria anodic catalytic layer evidenced that water produced from the electrochemical hydrogen oxidation provides steam for the internal reforming resulting in great stability of the fuel cells tested during ~100 h. The combined catalysis and SOFC results demonstrate Ni/doped-ceria is as candidate anode layer for stable SOFC running on bioethanol.

    Palavras-Chave: doped materials; cerium; solid oxide fuel cells; ethanol; cerium oxides; cermets

  • IPEN-DOC 27732

    GONCALVES, JOSEMARY A.C. ; MANGIAROTTI, ALESSIO; ASFORA, VIVIANE K.; KHOURY, HELEN J.; BUENO, CARMEN C. . The response of low-cost photodiodes for dosimetry in electron beam processing. Radiation Physics and Chemistry, v. 181, p. 1-8, 2021. DOI: 10.1016/j.radphyschem.2020.109335

    Abstract: The response of thin diodes (SFH206k) as dosimeters has been investigated employing the beam of an electron accelerator within the dose rate range of 2–8 kGy/s and accumulated doses up to 100 kGy. These devices, operating in the short-circuit mode and under industrial irradiation conditions, deliver current signals nonlinearly dependent on the dose rate, whichever the dose history of the diodes, due to the high density of the generated electron-hole pairs herein achieved. Despite this nonlinearity, the dose rate response is stable and characterized by current signals with repeatability better than 2.0%, regardless of the accumulated dose. It is also found that the dose responses are quite linear with sensitivities slightly dependent on the accumulated dose at a constant dose rate. The decrease in the charge sensitivity, taking as reference that obtained before any radiation damage, reaches only 9% (k = 2) at 100 kGy, which is much smaller than the values reported in the literature. From this low aging and the repeatability of both dose rate and dose responses, it seems that the photodiode under investigation is a low budget alternative, good enough for routine dosimetry, provided it has been previously calibrated in the same processing facility.

    Palavras-Chave: photodiodes; dosimetry; electron beams; dosemeters; electron dosimetry; si semiconductor detectors; dose rates

  • IPEN-DOC 27815

    SOUZA, SAUL H. de; PLAUT, RONALD L.; LIMA, NELSON B. de ; OLIVEIRA, RENE R. de ; PADILHA, ANGELO F.. The occurrence of a peripheral coarse grain zone (PCGZ) in extruded bars of AA 7108. Materials Science Forum, v. 1016, p. 1141-1146, 2021. DOI: 10.4028/www.scientific.net/MSF.1016.1141

    Abstract: Industrial-scale extruded profiles of AA 7108 with a rectangular section (25.60 mm x 15.95 mm) were used in this investigation. Some complementary microstructural analysis techniques, such as polarized light microscopy, EBSD (Electron Backscatter Diffraction) and X-ray diffraction were used to characterize the microstructure, focusing on the PCG zone. It was observed that the extruded profiles presented a totally recrystallized microstructure and a 300 μm layer of peripheral coarse grains. Additionally, the results showed that the PCGZ predominant grain orientation {311} <110> differs from the texture below the PCGZ (Goss and Cube components).

    Palavras-Chave: aluminium alloys; crystallography; microstructure; metallography; extrusion

  • IPEN-DOC 27787

    CAPPUZZELLO, FRANCESCO; ACOSTA, LUIS; AGODI, CLEMENTINA; BOZTOSUN, ISMAIL; BRISCHETTO, GIUSEPPE A.; CALABRESE, SALVATORE; CALABRETTA, LUCIANO; CALVO, DANIELA; CAMPAJOLA, LUIGI; CAPIROSSI, VITTORIA; CARBONE, DIANA; CAVALLARO, MANUELA; CHAVEZ, EFRAIN; CIRALDO, IRENE; DELAUNAY, FRANCK; DJAPO, HARIS; FERRARESI, CARLO; FINOCCHIARO, PAOLO; FISICHELLA, MARIA; GANDOLFO, ELISA M.; IAZZI, FELICE; MORALLES, MAURICIO ; NERI, LORENZO; OLIVEIRA, JOSE R.B.; PANDOLA, LUCIANO; PETRASCU, HORIA; PINNA, FEDERICO; RUSSO, ANTONIO D.; SARTIRANA, DIEGO; SGOUROS, ONOUFRIOS; SOLAKCI, S.O.; SOUKERAS, VASILEIOS; SPATAFORA, ALESSANDRO; TORRESI, DOMENICO; TUDISCO, SALVATORE; YILDIRIM, AYDIN. The NUMEN project: an update of the facility toward the future experimental campaigns. Frontiers in Astronomy and Space Sciences, v. 8, p. 1-15, 2021. DOI: 10.3389/fspas.2021.668587

    Abstract: The goal of NUMEN project is to access experimentally driven information on Nuclear Matrix Elements (NME) involved in the neutrinoless double beta decay (0νββ) by accurate measurements of the cross sections of heavy-ion induced double charge-exchange reactions. In particular, the (18O, 18Ne) and (20Ne, 20O) reactions are adopted as tools for β+β+ and β−β− decays, respectively. The experiments are performed at INFN–Laboratory Nazionali del Sud (LNS) in Catania using the Superconducting Cyclotron to accelerate the beams and the MAGNEX magnetic spectrometer to detect the reaction products. The measured cross sections are very low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. In order to make feasible a systematic study of all the candidate nuclei, a major upgrade of the LNS facility is foreseen to increase the experimental yield by more than two orders of magnitude. To this purpose, frontier technologies are being developed for both the accelerator and the detection systems. An update description of the NUMEN project is presented here, focusing on recent achievements from the R&D activity.

    Palavras-Chave: matrix elements; nuclear matrix; double beta decay; charge exchange; heavy ions; ion detection; magnetic spectrometers; gamma spectrometers

  • IPEN-DOC 27708

    LOPES, MONICA S.; PEREIRA, DAISA L. ; MOTA, CLAUDIA C.B. de O.; AMARAL, MARCELLO M.; ZEZELL, DENISE M. ; GOMES, ANDERSON S.L.. The lingual enamel morphology and bracket shear bond strength influenced by Nd:YAG laser and aluminum oxide sandblasting preconditioning. Clinical Oral Investigations, v. 25, n. 3, p. 1151-1158, 2021. DOI: 10.1007/s00784-020-03418-x

    Abstract: Objectives This study aimed to investigate the influence of Nd:YAG laser and aluminum oxide sandblasting on the shear bond strength (SBS) of lingual brackets and to optically analyze the behavior of the enamel morphology. Materials and methods Thirty-five bovines’ incisors teeth were divided into 5 groups (n = 7), according to the surface preconditioning: G1, control group; G2, Nd:YAG laser; G3, laser + aluminum oxide sandblasting (Al2O3); G4, Al2O3; and G5, Al2O3 + laser. All groups had lingual brackets bonded and shear debonded after 72 h. SBS values were analyzed, and the enamel morphology was evaluated by optical coherence tomography (OCT) and scanning electron microscope (SEM), before and after preconditioning surface. The optical attenuation coefficient (α) analysis was obtained from OCT images. Data analysis used the ANOVA test, followed by post hoc Tukey, Kruskal Wallis, and post hoc Dunn tests (significance of 5%). Results The SBS values presented similarly among groups, but the value of α showed statistical difference (p-value = 0.0124) between G3 and G5 with the others. Optical analyses indicated a melting on the enamel that suffered laser irradiation for G2 and G5 and crystal surface disorganization for G4. Sandblasting partially removes the melting of the laser effect (G3). Conclusion The sandblasting is a dispensable step for bonding lingual brackets, and the melting of the enamel after laser irradiation does not compromise the bracket adhesive resistance. Clinical relevance The Nd:YAG laser became an interesting tool to prevent caries and decrease prevalence of white spot lesions in orthodontic treatments, without systemic effects in patients with genetic high risks of caries.

    Palavras-Chave: dentistry; lasers; teeth; enamels; aluminium oxides; oral cavity; tongue; tomography

  • IPEN-DOC 27395

    COME, BENEDETTA; DONATO, MARESSA ; POTENZA, LUCIA F.; MARIANI, PAOLO; ITRI, ROSANGELA; SPINOZZI, FRANCESCO. The intriguing role of rhamnolipids on plasma membrane remodelling: from lipid rafts to membrane budding. Journal of Colloid and Interface Science, v. 582, n. Part B, p. 669-677, 2021. DOI: 10.1016/j.jcis.2020.08.027

    Abstract: Rhamnolipids (RLs) comprise a class of glycolipids produced by Pseudomonas aeruginosa under appropriate culture medium. They act as biosurfactants being composed by a hydrophilic head of either one (mono-RL) or two (di-RL) rhamnose moieties coupled to hydroxyaliphatic chains. It is well accepted that RLs present low biolitic activity as compared to other synthetic surfactants. However, their mechanisms of action in biological systems are not well defined yet. The interaction of RLs with lipid bilayers are here investigated to address how they impact on plasma membrane at molecular level. Our experimental approach was based on a deep analysis of optical microscopy data from giant unilamellar vesicles (GUVs) dispersed in aqueous solutions containing up to 0.5 mM of commercially available RLs (a mixture of mono-RL, 33–37 mol%, and di-RL, 63–67 mol%, cmc of 0:068 ± 0:005 mM). GUVs were made up of a single lipid POPC and a ternary system containing DOPC, sphingomyelin and cholesterol, which mimic lipid raft platforms. Our results demonstrate that RLs have a low partition in the lipid bilayer in respect to the total molecules in solution. We suppose that RLs insert in the outer leaflet with low propensity to flip-flop. In the case of POPC GUVs, the insertion of RL molecules in the outer leaflet impairs changes in spontaneous membrane curvature with incubation time. Then, small buds are formed that remain linked to the original membrane. No changes in membrane permeability have been detected. A remarkable result refers to the insertion of RLs in membranes containing liquid ordered (Lo) - liquid disordered (Ld) phase coexistence. The rate of interaction has been observed to be higher for Ld phase than for Lo phase (0:12 . 10-6 s-1 and 0:023 . 10-6 s-1 for Ld and Lo, respectively, at RL concentration of 0.5 mM). As a consequence, the preferential RL insertion in Ld phase may also alter the membrane spontaneous curvature which, coupled to the change in the line tension associated to the domains boundary, conducted to Lo domain protrusion. Even if it has been observed on a model system, such membrane remodelling might correlate to endocytic processes activated in cell membranes, regardless of the participation of specific proteins. Further, changes imposed by RLs in lipid rafts may affect the association of key proteins enrolled in cell signaling, which may perturb cell homeostasis.

    Palavras-Chave: membranes; lipids; cell membranes; microorganisms; plasma; pseudomonas; surfactants

  • IPEN-DOC 27869

    SANTOS, W.S.; NEVES, L.P.; PERINI, A.P.; SANTOS, C.J.; BELINATO, W.; CALDAS, L.V.E. . The influence of the lead eyewear geometry on the doses to the eye lens. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-9, 2021. DOI: 10.15392/bjrs.v9i1A.1347

    Abstract: The scattered radiation from interventional procedures is an important source of radiological risk for the medical staff. Considering all affected organs, the eye lens is among the most critical organs. As pointed out by several studies, even for low radiation doses, the appearance of cataract may occur. Considering this scenario, the radiation doses to the eye lens were determined using three different lead eyewear models commonly employed in the interventional radiology. The interventional radiologist was represented by an adult virtual anthropomorphic phantom (MASH3), coupled to the Monte Carlo code MCNP 6.1, in a typical cardiac interventional radiology procedure. The eyewear had a thickness 0.5 mmPb each, and the evaluation was carried out for four different beam angulations (PA, LAO90, LAO65 e RAO65), utilizing a tube voltage of 80 kVp, and HVL of 4 mmAl. The results pointed out that the shielding efficiency has a strong dependence on the eyewear type utilized, which may be very useful for the decision-making during the acquisition of such equipments.

    Palavras-Chave: crystalline lens; equivalent radiation doses; fluoroscopy; glass; lead; monte carlo method; occupational exposure; phantoms; radiation protection; shielding

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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

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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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Na página inicial nas referências são sinalizados todos os autores IPEN, ao clicar nesse símbolo será aberta uma nova página correspondente à aquele autor – trata-se da página do pesquisador.

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ATENÇÃO!

ESTE TEXTO "AJUDA" ESTÁ SUJEITO A ATUALIZAÇÕES CONSTANTES, A MEDIDA QUE NOVAS FUNCIONALIDADES E RECURSOS DE BUSCA FOREM SENDO DESENVOLVIDOS PELAS EQUIPES DA BIBLIOTECA E DA INFORMÁTICA.

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.