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  • Semi-monolithic meta-scintillator simulation proof-of-concept, combining accurate DOI and TOF
    2024 - KONSTANTINOU, GEORGIOS; ZHANG, LEI; BONIFACIO, DANIEL; LATELLA, RICCARDO; BENLLOCH, JOSE M.; GONZALEZ, ANTONIO J.; LECOQ, PAUL
    In this study, we propose and examine a unique semimonolithic metascintillator (SMMS) detector design, where slow scintillators (BGO or LYSO) are split into thin slabs and read by an array of SiPM, offering depth-of-interaction (DOI) information. These are alternated with thin segmented fast scintillators (plastic EJ232 or EJ232Q), also read by single SiPMs, which provides pixel-level coincidence time resolution (CTR). The structure combines layers of slow scintillators of size 0.3× 25.5× (15 or 24) mm3 with fast scintillators of size 0.1× 3.1× (15 or 24) mm3. We use a Monte Carlo Gate simulation to gauge this novel semimonolithic detector's performance. We found that the time resolution of SMMS is comparable to pixelated metascintillator designs with the same materials. For example, a 15-mm deep LYSO-based SMMS yielded a CTR of 121 ps before applying timewalk correction (after correction, 107-ps CTR). The equivalent BGO-based SMMS presented a CTR of 241 ps, which is a 15% divergence from metascintillator pixel experimental findings from previous works. We also applied neural networks to the photon distributions and timestamps recorded at the SiPM array, following guidelines on semimonolithic detectors. This led to determining the DOI with less than 3-mm precision and a confidence level of 0.85 in the best case, plus more than 2 standard deviations accuracy in reconstructing energy sharing and interaction energy. In summary, neural network prediction capabilities outperform standard energy calculation methods or any analytical approach on energy sharing, thanks to the improved understanding of photon distribution.
  • Probing the epoxy insulation of smoothing reactors with graphene ink
    2024 - FARIA, GABRIEL H. de; ARAUJO, LIVIA C. dos P.; LOPES, GUSTAVO P.; WANDERLEY NETO, ESTACIO T.; LEYVA, MARIA E.; QUEIROZ, ALVARO A.A. de
    Electrically conductive inks (ECIs) are up to now a growing research field, to create flexible circuits for power engineering. As a result, research into screen printing of conductive electrodes onto fiberglass-epoxy-reinforced laminates (FGERLs) has emerged. In this study, an ECI based on reduced graphene oxide (rGO) is proposed for screen printing of conductive electrodes on FGERL used in insulation of the high-voltage direct current smoothing reactors (HVDCSRs). The electrically conductive reduced graphene oxide ink (ECrGOI) was fabricated by mixing rGO, hyperbranched polyglycerol (HPGL) as an adhesion promoter, and poly (vinyl alcohol) (PVA) as a binding agent. The ECrGOI electrodes exhibited adhesion strength of 3.7 ± 0.3 N/mm2 and conductivity of 1.2.10-4 S/cm at percolation threshold starting at less than 7.5 wt.% of rGO. The thermogravimetric analysis (TGA) indicates that ECrGOI exhibited good thermal stability at 400 °C. The attractive electric, thermal, and adhesive properties, combined with the ease of preparation and solution-processing capability, indicate that ECrGOI may have great potential applications in analysis of insulation produced by FGERL used in encapsulation of smoothing reactors.
  • Electrical properties of silver-silicone rubber nanocomposites for high-voltage outdoor insulators
    2024 - ARAUJO, LIVIA C. dos P.; LEYVA, MARIA E.; WANDERLEY NETO, ESTACIO T.; QUEIROZ, ALVARO A.A. de
    Currently, the selection of high-temperature vulcanizing silicone rubber (HTVSiR) formulations resistant to the growth of microorganisms and which suitable electrical properties plays an important role in the manufacture of the polymeric high-voltage outdoor insulators (HVOIs) with high lifetime. In this work, silver-HTVSiR nanocomposites (AgHTVSiR) formulations are prepared and their electrical and antimicrobial properties are presented. Ag nanoparticles were electrochemically synthesized and characterized by scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), UV-visible (UV-Vis), and X-ray (XRD) spectroscopies. Thermogravimetric (TG/DTG) analysis is undertaken with the purpose of determining the thermal behavior of AgHTVSiR. The complex impedance analyses were conducted to investigate the electrical conduction mechanism of the AgHTVSiR nanocomposites via electrochemical impedance spectroscopy (EIS) within a frequency range from 0.1 Hz to 0.1 MHz. XRD revealed Ag nanoparticles of 50 nm in diameter size. The images of SEM-EDS evinced the homogeneity of Ag nanoparticles dispersion into the HTVSiR matrix. The incorporation of silver nanoparticles does not change the thermal stability of the AgHTVSiR nanocomposite as compared to neat HTVSiR. The AgHTVSiR nanocomposites have maximal values for real part (Z') at low frequencies. Z' is found to decrease as the frequency of the applied alternating electric field increases. Furthermore, there is an improvement in the permittivity values for the AgHTVSiR nanocomposites with an increase in the concentration of 0.1 wt.%-0.3 wt.% of the Ag nanoparticles. Also, the AgHTVSiR shows excellent antimicrobial efficacy against Trichoderma spp fungus. The impedance characteristics of the AgHTVSiR nanocomposite along with its high dielectric permittivity and excellent antimicrobial property make it suitable for application in HVOI.
  • Artigo IPEN-doc 30455
    Evaluation of micronuclei, cytomorphometric and cytologic changes of the oral mucosa in hookah and cigarette smokers
    2024 - INOSTROZA, ELVIRA A.S.; BRESSANE, ADRIANO; SCHWARMEIER, LIGIA A.T.; LACERDA, ESTER B.; ANJOS, KARINE R. dos; SANTOS, THAMIRES S.P. dos; CAVALCANTI, DESIREE R.; NASCIMENTO, FABIO D.; ALMEIDA, JANETE D.; ALVES, MONICA G.O.
    Objective. To analyze the effect of hookah and cigarettes on the oral mucosa of smokers through the use of exfoliative cytology. Study Design. Smear samples were collected by exfoliative cytology from the tongue of 33 hookah smokers, 22 cigarette smokers, and 30 non-smokers. The selected analyses include micronuclei (MN), metanuclear anomalies, epithelial maturation, and cytomorphology (nuclear area [NA], cytoplasmic area [CA], and NA/CA ratio). Results. The largest differences observed for MN and metanuclear anomalies were between cigarette smokers and the control group (notably 1 MN P = .04; total cells with MN P = .039; total MN P = .042; karyorrhexis and binucleation, P = .0001). The hookah group, compared with the control group, showed the greatest differences for karyolysis (P = .0023), binucleation (P = .0003), and broken egg (P = .008). Significant differences were found between the smokers and the control groups regarding changes in the superficial cell without nucleus, perinuclear halo, vacuolization, color change, mucus, and keratohyalin granules. There was a significant increase in the NA and NA/CA ratio in the smoker groups. Conclusion. This study showed that a combined analysis of exfoliative cytology associated with other diagnostic methods is a useful tool for studying oral carcinogenesis. Hookah and cigarettes showed similar effects in terms of displaying substantial cytogenetic and cytotoxic damage.
  • Artigo IPEN-doc 30405
    Leveraging citizen science for monitoring urban forageable plants
    2024 - SOARES, FILIPE M.; PIRES, LUIS F.; GARCIA, MARIA C.; CORADIN, LIDIO; GHILARDI-LOPES, NATALIA P.; SILVA, RUBENS R.; CARVALHO, ALINE M. de; GAVAI, ANAND; BOUZEMBRAK, YAMINE; KOFFLER, SHEINA; MONTEDO, UIARA B.; DRUCKER, DEBORA P.; SANTIAGO, RAQUEL; MACULAN, BENILDES C.M. dos S.; CARVALHO, MARIA C.P. de; LIMA, ANA C. da S.; GABRIEL, HILLARY D.E.; FRANCA, STEPHANIE G.M. de; ALMEIDA, KAROLINE R. de; SANTOS, BARBARA J. dos; SARAIVA, ANTONIO M.
    Urbanization brings forth social challenges in emerging countries such as Brazil, encompassing food scarcity, health deterioration, air pollution, and biodiversity loss. Despite this, urban areas like the city of São Paulo still boast ample green spaces, offering opportunities for nature appreciation and conservation, enhancing city resilience and livability. Citizen science is a collaborative endeavor between professional scientists and nonprofessional scientists in scientific research that may help to understand the dynamics of urban ecosystems. We believe citizen science has the potential to promote human and nature connection in urban areas and provide useful data on urban biodiversity.
  • Artigo IPEN-doc 30404
    Citizen science data on urban forageable plants
    2024 - SOARES, FILIPE M.; PIRES, LUIS F.; GARCIA, MARIA C.; CORADIN, LIDIO; GHILARDI-LOPES, NATALIA P.; SILVA, RUBENS R.; CARVALHO, ALINE M. de; GAVAI, ANAND; BOUZEMBRAK, YAMINE; MACULAN, BENILDES C.M. dos S.; KOFFLER, SHEINA; MONTEDO, UIARA B.; DRUCKER, DEBORA P.; SANTIAGO, RAQUEL; CARVALHO, MARIA C.P. de; LIMA, ANA C. da S.; GABRIEL, HILLARY D.E.; FRANCA, STEPHANIE G.M. de; ALMEIDA, KAROLINE R. de; SANTOS, BARBARA J. dos; SARAIVA, ANTONIO M.
    This paper presents two key data sets derived from the Pomar Urbano project. The first data set is a comprehensive catalog of edible fruit-bearing plant species, native or introduced to Brazil. The second data set, sourced from the iNaturalist platform, tracks the distribution and monitoring of these plants within urban landscapes across Brazil. The study includes data from the capitals of all 27 federative units of Brazil, focusing on the ten cities that contributed the most observations as of August 2023. The research emphasizes the significance of citizen science in urban biodiversity monitoring and its potential to contribute to various fields, including food and nutrition, creative industry, study of plant phenology, and machine learning applications. We expect the data sets presented in this paper to serve as resources for further studies in urban foraging, food security, cultural ecosystem services, and environmental sustainability.
  • Artigo IPEN-doc 30403
    New GATE Digitizer Unit for versions post v9.3
    2024 - KOCHEBINA, OLGA; BONIFACIO, DANIEL A.B.; KONSTANTINOU, GEORGIOS; PAILLET, ADRIEN; POMMRANZ, CHRISTIAN M.; RAZDEVSEK, GASPER; SHARYY, VIATCHESLAV; YVON, DOMINIQUE; JAN, SEBASTIEN
    The Digitizer Unit plays an important role in modeling using Geant4 Application for Tomographic Emission (GATE), a Geant4-based platform used for numerical simulations in medical imaging and radiotherapy. It simulates the response of the photodetection components using a sequence of analytical and semi-analytical models. The Digitizer Unit was written for the first version of GATE approximately 20 years ago. Since then, it has in parts grown in a code that can be hardly maintained. Some parts of the code were unused or duplicated; some of the functionalities were not working anymore. Therefore, the GATE Digitizer Unit update is required in order to incorporate the novelties of Geant4 to update its current version and add new features. In this article, the implementation of the new GATE Digitizer Unit (since version 9.3) is presented. Added functionalities, the impact of changes on users, the current status of the work, and perspectives are discussed.
  • Artigo IPEN-doc 30402
    Biodegradable scaffold
    2024 - SIQUEIRA, ANDRE da S.; BRAGA, NATALIA F.; MUNOZ, PABLO A.R.; FREITAS, LUCAS F. de; FERREIRA, ARYEL H.; FECHINE, GUILHERMINO J.M.
    Extensive research and practical applications have been conducted within the biomaterials domain, focusing on polylactic acid (PLA) based composite. These composites have been explored for their favorable attributes, such as excellent processability, biodegradability, and bioactivity properties, but still lack mechanical properties. In this work, PLA-based nanocomposites were prepared by incorporating hydroxyapatite (HA) and graphene oxide (GO) via melt mixing (extruder). Filaments were obtained to develop scaffolds through 3D printing, utilizing the fused deposition method (FDM). The GO was produced using Hummer’s method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman Spectroscopy. The composites were analyzed using Fourier-transform infrared spectroscopy (FTIR), molecular weight, contact angle measurements, and thermal, mechanical, and rheological analysis. Adding only 0.05 wt% of GO to both PLA and PLA/HA resulted in enhancements in mechanical properties, particularly tensile strength, and significantly modified the surface properties of the materials studied. Specifically, formulation involving PLA/HA/GO was the only one to exhibit rheological properties compatible with the scaffold production process via FDM. These specific formulations were also investigated regarding cytotoxicity, and the presence of GO induces good cytocompatibility in mouse osteoblast cells (MC3T3). These results suggest that FDM technology can be used to fabricate higher-performance (mechanical and biological) scaffolds for tissue engineering.
  • Artigo IPEN-doc 30401
    Emerging pollutants in textile wastewater
    2024 - GARCIA, VANESSA S.G.; TOMINAGA, FLAVIO K.; ROSA, JORGE M.; BORRELY, SUELI I.
    Water and several chemicals, including dyestuffs, surfactants, acids, and salts, are required during textile dyeing processes. Surfactants are harmful to the aquatic environment and induce several negative biological effects in exposed biota. In this context, the present study aimed to assess acute effects of five surfactants, comprising anionic and nonionic classes, and other auxiliary products used in fiber dyeing processes to aquatic organisms Vibrio fischeri (bacteria) and Daphnia similis (cladocerans). The toxicities of binary surfactant mixtures containing the anionic surfactant dodecylbenzene sulfonate + nonionic fatty alcohol ethoxylate and dodecylbenzene sulfonate + nonionic alkylene oxide were also evaluated. Nonionic surfactants were more toxic than anionic compounds for both organisms. Acute nonionic toxicity ranged from 1.3 mg/L (fatty alcohol ethoxylate surfactant) to 2.6 mg/L (ethoxylate surfactant) for V. fischeri and from 1.9 mg/L (alkylene oxide surfactant) to 12.5 mg/L (alkyl aryl ethoxylated and aromatic sulfonate surfactant) for D. similis, while the anionic dodecylbenzene sulfonate EC50s were determined as 66.2 mg/L and 19.7 mg/L, respectively. Both mixtures were very toxic for the exposed organisms: the EC50 average in the anionic + fatty alcohol ethoxylate mixture was of 1.0 mg/L ± 0.11 for V. fischeri and 4.09 mg/L ± 0.69 for D. similis. While the anionic + alkylene oxide mixture, EC50 of 3.34 mg/L for D. similis and 3.60 mg/L for V. fischeri. These toxicity data suggested that the concentration addition was the best model to explain the action that is more likely to occur for mixture for the dodecylbenzene sulfonate and alkylene oxide mixtures in both organisms. Our findings also suggest that textile wastewater surfactants may interact and produce different responses in aquatic organisms, such as synergism and antagonism. Ecotoxicological assays provide relevant information concerning hazardous pollutants, which may then be adequately treated and suitably managed to reduce toxic loads, associated to suitable management plans.
  • Artigo IPEN-doc 30454
    Unraveling grain growth of metallic tungsten
    2024 - ESTUPINAN-DONOSO, ALVARO A.; GRAVIER, PAULINE; ICHIKAWA, RODRIGO U.; MICHELS, ANDREAS
    This paper focuses on the experimental observation of tungsten grain evolution during the process of hydrogen reduction of tungsten trioxide. The objective is to gain insights into the grain size distribution (GSD) evolution and morphology changes of metallic tungsten. The study employs an amalgamation of conventional characterization techniques – such as TGA, SEM-EDS, TEM and XRD – alongside cutting-edge techniques like phase contrast nano-tomography from synchrotron sources. Conducted as a quasi in-situ study, this research offers the opportunity to observe the transient evolution of the formed metallic tungsten phase within its precursor WO2 particles. The paper presents and discusses quantitative results concerning the evolution of GSD and morphological changes, encompassing growth rates of both crystallites and grains of the synthesized metallic phase. Additionally, the quasi in-situ study highlights the dependence of grain size on water concentration during the reduction process. The qualitative and quantitative findings contribute to a more nuanced understanding of the kinetics of grain growth of metallic tungsten and offer insights into the intricate interplay between reduction parameters, GSD evolution and morphological changes. Gaining a deeper understanding of the underlying mechanisms driving the changes in GSD establishes a foundation for predictive theory with immediate academic and industrial impact.
  • Artigo IPEN-doc 30453
    Fragmentation of fuel particles in rolling U3Si2-Al dispersion fuel plates
    2024 - DURRAZO, MICHELANGELO; MARCONDES, GILBERTO H.; CARVALHO, ELITA F.U. de; BARROS, GUILHERME D. de; LEAL NETO, RICARDO M.
    The Nuclear and Energy Research Institute (IPEN-CNEN/SP) has recently developed a process to produce the nuclear fuel required to run the Brazilian Multipurpose Reactor (RMB), using U3Si2-Al dispersion in plate-type fuel elements. Since the late 1980s, regular production of dispersion-based fuel plates has kept the maximum fines content (<44 μm) of 20 wt%. However, IPEN’s U3Si2 powder manufacturing process typically generates fines between 25 and 30 wt%, making it necessary to discard and recycle about 5 to 10 wt% of the powder during manufacturing. The severe fines requirements necessitate careful comminution with multiple intermediate screening steps, which has a negative impact on RMB’s fuel production scalability (60 elements per year). To improve the current fines content specification for the powder, this study focuses on looking into U3Si2 particle fragmentation during fuel plate manufacturing. Quantitative microscopy methods and image analysis were employed. The findings revealed a significant increase in fines content during the rolling process, with levels reaching up to 59 wt%. Hence, to ensure high-quality dispersion, it becomes crucial to specify the fines content in the fuel plate obtained after rolling rather than just in the original powder. The results recommend that a new U3Si2 powder specification could allow a maximum fine content of 30 wt%. More research is ongoing to confirm this recommendation.
  • Artigo IPEN-doc 30400
    Synthesis of sustainable mesoporous sulfur-doped biobased carbon with superior performance sodium diclofenac removal
    2024 - REIS, GLAYDSON S. dos; GRIMM, ALEJANDRO; FUNGARO, DENISE A.; HU, TAO; BRUM, IRINEU A.S. de; LIMA, EDER C.; NAUSHAD, MU; DOTTO, GUILHERME L.; LASSI, ULLA
    Over the last years, the strategy of employing inevitable organic waste and residue streams to produce valuable and greener materials for a wide range of applications has been proven an efficient and suitable approach. In this research, sulfur-doped porous biochar was produced through a single-step pyrolysis of birch waste tree in the presence of zinc chloride as chemical activator. The sulfur doping process led to a remarkable impact on the biochar structure. Moreover, it was shown that sulfur doping also had an important impact on sodium diclofenac (S-DCF) removal from aqueous solutions due to the introduction of S-functionalities on biochar surface. The adsorption experiments suggested that General and Liu models offered the best fit for the kinetic and equilibrium studies, respectively. The results showed that the kinetic was faster for the S-doped biochar while the maximum adsorption capacity values at 318 K were 564 mg g−1 (non-doped) and 693 mg g−1 (S-doped); highlighting the better affinity of S-doped biochar for the S-DCF molecule compared to non-doped biochar. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) suggested that the S-DCF removal on both adsorbents was spontaneous, favourable, and endothermic.
  • Artigo IPEN-doc 30399
    The pattern of GH action in the mouse brain
    2024 - MENEZES, FILIPE; WASINSKI, FREDERICK; SOUZA, GABRIEL O. de; NUNES, AMANDA P.; BERNARDES, EMERSON S.; SANTOS, SOFIA N. dos; SILVA, FABIO F.A. da; PERONI, CIBELE N.; OLIVEIRA, JOAO E.; KOPCHICK, JOHN J.; BROWN, ROSEMARY S.E.; FERNANDEZ, GIMENA; DE FRANCESCO, PABLO N.; PERELLO, MARIO; SOARES, CARLOS R.J.; DONATO JUNIOR, JOSE
    GH acts in numerous organs expressing the GH receptor (GHR), including the brain. However, the mechanisms behind the brain's permeability to GH and how this hormone accesses different brain regions remain unclear. It is well-known that an acute GH administration induces phosphorylation of the signal transducer and activator of transcription 5 (pSTAT5) in the mouse brain. Thus, the pattern of pSTAT5 immunoreactive cells was analyzed at different time points after IP or intracerebroventricular GH injections. After a systemic GH injection, the first cells expressing pSTAT5 were those near circumventricular organs, such as arcuate nucleus neurons adjacent to the median eminence. Both systemic and central GH injections induced a medial-to-lateral pattern of pSTAT5 immunoreactivity over time because GH-responsive cells were initially observed in periventricular areas and were progressively detected in lateral brain structures. Very few choroid plexus cells exhibited GH-induced pSTAT5. Additionally, Ghr mRNA was poorly expressed in the mouse choroid plexus. In contrast, some tanycytes lining the floor of the third ventricle expressed Ghr mRNA and exhibited GH-induced pSTAT5. The transport of radiolabeled GH into the hypothalamus did not differ between wild-type and dwarf Ghr knockout mice, indicating that GH transport into the mouse brain is GHR independent. Also, single-photon emission computed tomography confirmed that radiolabeled GH rapidly reaches the ventral part of the tuberal hypothalamus. In conclusion, our study provides novel and valuable information about the pattern and mechanisms behind GH transport into the mouse brain.
  • Artigo IPEN-doc 30452
    Strong Raman enhancement in structured colloids
    2024 - DIPOLD, JASSICA; WETTER, NIKLAUS U.; MARQUES, FRANCISCO C.; FREITAS, ANDERSON Z.; DOGARIU, ARISTIDE; JIMENES-VILLAR, ERNESTO
    Raman spectroscopy is a powerful technique for studying the interaction between light and matter. Here we show a significant enhancement of Raman emission over a broad range of pumping wavelengths from strongly scattering media comprising spatially correlated photonic structures of core–shell TiO2@Silica scatterers mixed with silica nanoparticles and suspended in ethanol. Long-range Coulomb interactions between nanoparticles inside these photonic colloidal structures induce a correlation in the scatterers’ positions (TiO2@Silica), affecting local and global photonic properties. The anomalous enhancement in Raman signal increases as the scattering strength is increased (through either scatterer concentration or pumping wavelength); however, the signal strength continues to behave linearly with excitation power, ruling out classical nonlinear and interferential phenomena. These observations may indicate strong photon correlation in strongly localized electromagnetic modes, inducing successive photon interactions with the atoms or molecules. Aside from the fundamental relevance to understanding measurable properties in this regime of strongly localized electromagnetic modes, our demonstration of strongly enhanced Raman emission over a broad range of pumping wavelengths provides new opportunities for the development of advanced photonic materials and devices.
  • Artigo IPEN-doc 30451
    Outcomes and achievements from researches orienting the future in nuclear fission technology
    2024 - COSTA, ANTONELLA L.; PALMA, DANIEL A.P.; GENEZINI, FREDERICO; STEFANI, GIOVANNI L. de
    Brazil, Peru and Bolivia are neighboring countries with geographic borders in the northern region of Brazil and they are 3 of the 12 countries in South America. From the 12 countries, only two have nuclear power plants: Argentina and Brazil, with low share of nuclear in their national energy mixes being about 3 % of the total electricity production in Brazil and around 4 % in Argentina. However, in Brazil and Argentina the nuclear technology is already well established and this greatly facilitates the expansion program if established by the government.
  • Artigo IPEN-doc 30398
    Toxicological response of Saccharomyces cerevisiae to acetylsalicylic acid aqueous solution treated by electron beam irradiation
    2023 - TOMINAGA, FLAVIO K.; LEO, PATRICIA; BORRELY, SUELI I.
    Pharmaceuticals have drawn attention due to the potential of causing negative impacts on the population and ecosystems at ecological relevant concentrations. Among these contaminants, acetylsalicylic acid is a drug widely used in human medicine as an analgesic, antipyretic and in actively preventing blood platelet aggregation, which has been introduced into the environment continuously. Several technologies have been proposed for the removal of contaminants. Electron beam irradiation (EBI) has been applied as an alternative and clean technology for pollutant removal. Nevertheless, after any type of treatment there may occur the formation of more toxic byproducts, which may be detected by biological assays. The Saccharomyces cerevisiae yeast consists in simple eukaryotic model, widely used for the assessment of toxic effects on human cells and tissues. This work aims the toxicity assessment of treated acetylsalicylic aqueous solutions by EBI employing Saccharomyces cerevisiae. Toxicity assays were performed with S. cerevisiae and the results were compared to others aquatic organisms (Vibrio fischeri bioluminescent bacteria and Daphnia similis microcrustacean). The results showed low sensibility to the yeast when exposed to the anti-inflammatory, demonstrating an EC5030min of 815 mg L-1, when compared with the bioluminescent bacteria (EC5015min = 38.48 mg L-1) and the microcrustacean (EC5048h = 86.05 mg L-1). Due to low acute toxicity, chronic assays were also performed with D. similis, demonstrating a NOEC14days of 2.5 mg L-1. Based on these results, toxicity data from chronic assays was utilized for PNEC estimation, and the highest concentration detected in Brazilian surface water was used to evaluate the worst-case scenario. The calculated risk quotient indicated a possible risk of acetylsalicylic acid to aquatic biota. After EBI treatment, increase in toxicity have been noted for all the evaluated organisms, indicating sensibility of the evaluated organism. This work demonstrated the feasibility of employing toxicity assays with the Saccharomyces cerevisiae yeast.
  • Artigo IPEN-doc 30397
    Convolutional neural network-based pattern recognition in natural circulation instability images
    2024 - SCHOTT, SANDRO M.C.; SILVA, MARCONES C.B. da; ANDRADE, DELVONEI A. de; MESQUITA, ROBERTO N. de
    Heat removal systems employing natural circulation are key in new nuclear power plant designs for mitigating accidents. This study applies Convolutional Neural Networks (CNNs) to classify 'chugging' instability phases, analyzing 1152 two-phase flow images from a Natural Circulation Circuit. Three CNN models, including one incorporating transfer learning from the ImageNet database, were trained via five-fold cross-validation to fine-tune hyperparameters. This involved comparing models with and without transfer learning against a baseline linear model. A model using a pre-trained Resnet50 with transfer learning accurately classified all 230 samples, outperforming the baseline linear model with an F1-Score of 0.859. The results endorse the use of CNNs with transfer learning for thermohydraulic image analysis in identifying natural circulation instability stages.
  • Artigo IPEN-doc 30450
    Improved relative gain in Nd3+doped GeO2-PbO glass with double waveguides irradiated by femtosecond laser micromachining and decorated with Au nanoparticles
    2024 - BORDON, CAMILA D.S.; DIPOLD, JESSICA; VECCHI, THIAGO F.; WETTER, NIKLAUS U.; ROSSI, WAGNER de; FEITAS, ANDERSON Z.; KASSAB, LUCIANA R.P.
    The paper explores the effects of Au nanoparticle (NP) islands deposited by sputtering technique on the surface of Nd3+-doped GeO2-PbO glasses, with double-line waveguides, produced via femtosecond laser processing for photonics. A Ti:sapphire femtosecond laser operating at 800 nm was employed to inscribe the waveguides directly into the glass, 0.7 mm beneath the surface. These waveguides were structured as pairs of parallel lines separated 10 μm. Additional procedures were undertaken to position the waveguides on the glass surface where Au NPs were deposited. Refractive index change of 10− 3 at 632 nm was observed in both horizontal and vertical directions. Similar results for the beam quality factors (Mx2 and My2) at 632 nm and 1064 nm indicated x, y-symmetrical guiding. Photoluminescence and relative gain growth were observed due to Au NP islands. The relative gain reached 3.0 dB/cm representing an increase of approximately 450 % when compared to samples without the Au NP islands, and was attributed to the local field growth in their vicinities. This study highlights the potential to change Nd3+-doped GeO2-PbO glasses optical properties with Au nanoparticle islands, opening up new and promising prospects for photonics and 1064 nm optical amplifiers.
  • Artigo IPEN-doc 30396
    Deep neural networks can differentiate thyroid pathologies on infrared hyperspectral images
    2024 - BAFFA, MATHEUS de F.O.; ZEZELL, DENISE M.; BACHMANN, LUCIANO; PEREIRA, THIAGO M.; DESERNO, THOMAS M.; FELIPE, JOAQUIM C.
    Background and objective: The thyroid is a gland responsible for producing important body hormones. Several pathologies can affect this gland, such as thyroiditis, hypothyroidism, and thyroid cancer. The visual histological analysis of thyroid specimens is a valuable process that enables pathologists to detect diseases with high efficiency, providing the patient with a better prognosis. Existing computer vision systems developed to aid in the analysis of histological samples have limitations in distinguishing pathologies with similar characteristics or samples containing multiple diseases. To overcome this challenge, hyperspectral images are being studied to represent biological samples based on their molecular interaction with light. Methods: In this study, we address the acquisition of infrared absorbance spectra from each voxel of histological specimens. This data is then used for the development of a multiclass fully-connected neural network model that discriminates spectral patterns, enabling the classification of voxels as healthy, cancerous, or goiter. Results: Through experiments using the k-fold cross-validation protocol, we obtained an average accuracy of 93.66 %, a sensitivity of 93.47 %, and a specificity of 96.93 %. Our results demonstrate the feasibility of using infrared hyperspectral imaging to characterize healthy tissue and thyroid pathologies using absorbance measurements. The proposed deep learning model has the potential to improve diagnostic efficiency and enhance patient outcomes.
  • Artigo IPEN-doc 30449
    Core reduction for increasing neutron flux and radioisotope production in the IEA-R1 research reactor
    2024 - VIGGIANO, FELIPE; STEFANI, GIOVANNI L. de; GENEZINI, FREDERICO A.; MOREIRA, JOAO M.L.; CUNHA, CAIO J.C.M.
    This work aims to present and analyze a new reactor core configuration for the IEA-R1 reactor core with the objective of enhancing its neutron irradiation capabilities. The reactor was modeled using the KENO-VI module from the SCALE Code System, provided by ORNL. Results have shown that implementing a near-cylindrical configuration in the IEA-R1 core could substantially increase neutron flux, particularlly in the center irradiation positions such as the EIBe (Beryllium Irradiated Element). After comparing various configurations, we conducted a brief analysis of the proposed core configuration’s potential to produce 177Lu, resulting in a 34% increase in the specific activity of 177Lu considering a 14-day full power cycle.