Navegação IPEN por ano de publicação "2021"

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  • IPEN-DOC 28393

    MORAIS, ALINE V. de; MELO, CAMILA G. ; GARCIA, VANESSA S.G. ; PEREIRA, MARIA da C.C. ; ROSA, JORGE M.; BORRELY, SUELI I. . Toxicidade do efluente e consumo hídrico e energético no tingimento de poliamida. In: SILVEIRA, JOSE H.P. (Org.). Meio Ambiente, Sustentabilidade e Tecnologia. Belo Horizonte, MG: Poisson, 2021. p. 91-97, v. 8, cap. 9. DOI: 10.36229/978-65-5866-123-8.CAP.09

    Abstract: O uso racional da água é imprescindível no setor industrial e deste modo necessita de tecnologia e esforços que permitam o reuso desse recurso natural. O estudo concentrou-se na determinação do consumo hídrico e energético durante o tingimento da poliamida, bem como na avaliação do efeito tóxico do efluente para o microcrustáceo Daphnia similis. O efluente pode ser considerado como muito tóxico tendo em vista que a CE50 foi 0,61 ± 0,21 (%, v/v) após 48 horas de exposição. Conforme orientação da Resolução CONAMA 430/2011 o efluente deve ser tratado em nível tal que não induza toxicidade quando lançado no corpo receptor. Buscas por tecnologias que permitam o reúso e a melhoria dos efluentes também são necessários nessa atividade industrial.

    Palavras-Chave: liquid wastes; textile industry; water pollution; daphnia; dyes; water resources; polyamides; environment; toxic materials

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  • IPEN-DOC 29329

    TOMINAGA, F.K. ; BOIANI, N.F. ; GARCIA, V.S.G. ; SILVA, T.T. ; LEO, P.; BORRELY, S.I. . Toxicidade aguda e avaliação de riscos ecológicos de fármacos pertencentes a diferentes classes detectados em ambientes aquáticos. In: CONGRESSO BRASILEIRO DE ECOTOXICOLOGIA, 16., 16-19 de agosto, 2021, Online. Anais... 2021.

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  • IPEN-DOC 28484

    CABRAL, FERNANDA V. . Towards new therapeutic strategies for cutaneous leishmaniasis / Buscando novas estratégias terapêuticas para o tratamento de leishmaniose cutânea . 2021. Tese (Doutorado em Tecnologia Nuclear) - Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, São Paulo. 123 p. Orientador: Martha Simões Ribeiro. DOI: 10.11606/T.85.2021.tde-18112021-095721

    Abstract: Cutaneous leishmaniasis (CL) is a zoonotic disease developed by protozoa parasites of genus Leishmania. It promotes destructive and ulcerated lesions with limited treatment options. There is an urgent need for the development of topical, cost-effective and efficacious treatments with minimized side effects to treat affected patients. The parasite-host interaction is of great importance since Leishmania parasites survive and replicate within host macrophages. As phagocytic cells, the activated macrophages produce reactive oxygen species (ROS) and nitric oxide (NO), which are toxic to pathogens, hence preventing parasites proliferation. However, Leishmania parasites can evade the host immune response and subvert antimicrobial macrophage defenses, thereby surviving within these cells even in harsh conditions. Indeed, the role played by ROS and NO in the control of CL has been under debate over the past years, emerging as potential alternatives to tackle this important neglected disease. In this regard, we aimed to evaluate the role of both NO and ROS towards antileishmanial activity using two different therapeutic strategies: (1) nitric oxide-releasing chitosan nanoparticles (NONPs) and (2) antimicrobial photodynamic therapy (PDT). For this, we focused on development and investigation of the potential of NONPs in vitro and in vivo against Leishmania amazonensis, one of the causative agents of CL. To assess the role of ROS, photodynamic therapy was investigated against different Leishmania species. Firstly, we evaluated the potential of organic light-emitting diodes (OLEDs) as a novel light source to inactivate in vitro promastigotes of L. major and L. amazonensis, using three phenothiazine dyes: Methylene blue, new methylene blue and 1,9-dimethyl methylene blue (DMMB). Then, we addressed the underlying mechanisms of DMMB-PDT upon promastigotes of L. amazonensis wild-type (WT) and miltefosineresistant (MFR) strains. DMMB-PDT effectiveness was also evaluated against intracellular amastigotes of WT and MFR together with cytotoxicity assay on mammalian cells. Our findings demonstrate that either NONPs or PDT are promising strategies to target CL and should be further explored for future preclinical and clinical trials.

    Palavras-Chave: parasites; trypanosomes; skin diseases; chemical oxygen demand; nitric oxide; spectroscopy; light emitting diodes

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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 28586

    VIEIRA, DANIEL P. . Three-dimensional cellular culture system for testing of biological effects of radiations in tumoral and non-tumoral models. In: CONGRESS OF THE INTERNATIONAL UNION FOR PURE APPLIED BIOPHYSICS, 20th; ANNUAL MEETING OF THE BRAZILIAN SOCIETY FOR BIOCHEMISTRY AND MOLECULAR BIOLOGY, 50th; CONGRESS OF BRAZILIAN BIOPHYSICS SOCIETY, 45th; BRAZILIAN SOCIETY ON NUCLEAR BIOSCIENCES CONGRESS, 13th, October 4-8, 2021, São Paulo, SP. Abstract... São Paulo, SP: Sociedade Brasileira de Bioquímica e Biologia Molecular (SBBq), 2021. p. 89-89.

    Abstract: In vitro cell cultures are a well-known controlled test system used to analyze tumor physiologic responses upon negative stimuli. Updated techniques, us-ing three-dimensional organization of cells in cultures, are being increasingly used to this purpose. Research organizations and industry are striving to pro-duce in vitro tumor surrogates that could be better test systems to antitumor agents as new compounds or to study radiation effects on cancers. The presentation will show some techniques currently used to build and maintain these specific cell cultures, and how experiments are evolving towards the production of tumoroids, or tumoral organoids, which will include various cell types and additive manufacturing.

    Palavras-Chave: cell cultures; three-dimensional calculations; tumor cells; radiations

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  • IPEN-DOC 28619

    VIEIRA, DANIEL P. . Three-dimensional cellular culture system for testing of biological effects of radiations in tumoral and non-tumoral models. Biophysical Reviews, v. 13, n. 6, p. 1521-1521, 2021. DOI: 10.1007/s12551-021-00844-3

    Abstract: In vitro cell cultures are a well-known controlled test system used to analyze tumor physiologic responses upon negative stimuli. Updated techniques, us-ing three-dimensional organization of cells in cultures, are being increasingly used to this purpose. Research organizations and industry are striving to pro-duce in vitro tumor surrogates that could be better test systems to antitumor agents as new compounds or to study radiation effects on cancers. The presentation will show some techniques currently used to build and maintain these specific cell cultures, and how experiments are evolving towards the production of tumoroids, or tumoral organoids, which will include various cell types and additive manufacturing.

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  • IPEN-DOC 28288

    BARIA, R. ; WATANABE, S.; MUNITA, C.S. ; SILVA, P.S.C. ; TATUMI, S.H.. Thorium, uranium and potassium levels of Brazil geological sediment by gamma-ray spectrometer and instrumental neutron activation analysis. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, November 29 - December 2, 2021, Online. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2021.

    Palavras-Chave: comparative evaluations; geology; neutron activation analysis; potassium; seawater; seaweeds; sediments; thorium; uranium; x-ray spectroscopy

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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 28055

    PRADO, MARILIZA C. de O. . Thermal damage and time of excision of micro and super pulsed diode lasers : an ex-vivo comparative study / Dano térmico e tempo de excisão dos lasers de diodo micro e superpulsado: um estudo comparativo ex-vivo . 2021. Tese (Doutorado em Tecnologia Nuclear) - Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, São Paulo. 138 p. Orientador: Denise Maria Zezell. DOI: 10.11606/T.85.2021.tde-08092021-150518

    Abstract: Diode lasers are portable, accessible, efficient and reliable surgical units for performing surgeries and soft tissue biopsies of the oral cavity. The newer units are equipped with micro and super pulsed technologies and systems that allow the selection of different usage parameters in terms of emission mode, duty cycle, power and pulse duration. It is, however, not known which parameters or types of diode lasers produce the most intact tissue samples in the best possible surgical time. The main objective of this ex vivo study was to compare the thermal damage and the excision time of different parameters of the micro pulsed diode laser and the super pulsed diode laser. The secondary objectives were: 1) to provide practical recommendations for performing surgical excisions with diode lasers; 2) to examine possible correlations between the area and the depth of the thermal damage, as well as between the time of excision and the thermal damage. Ten groups of ten swine tongue specimens were excised (8 mm in diameter) using a surgical blade (control group: G1); micro pulsed diode laser in different emission modes, duty cycles, average power, peak power and pulse duration (G2 - 9); and the new super pulsed diode laser (G10) with the smallest single parameter recommended by the manufacturer (average power = 3.2W, peak power = 80 W, pulse duration from 10 μs to 100 ms). The wavelength of both was 940 nm. All parameters were previously measured with the power meter and activated disposable tips were discarded right after each biopsy. The area and the histological depth of the thermal damage were quantified using the NIS-Element Basic Research software (Nikon Instruments Inc), while the excision time was measured between the clamping until the total excision of the lesion. Kruskal-Wallis and Dunn's multiple comparison tests with Bonferroni correction were applied to compare the area and depth of thermal damage, as well as the time of excision between the groups. Correlations between area and depth of thermal damage and between excision time and thermal damage were examined using Spearman's nonparametric correlation coefficient. The level of significance was set at 5%. In the experimental groups (G2 - G10), the total area of thermal damage observed was smaller in the G3 group (continuous mode, average power = 1.5W; median = 0.91 mm2 ; p = 0.009). All other groups had thermal damage areas larger than 1 mm2 with G7 (pulsed mode, duty cycle = 33%, average power = 1.5W, peak = 5.4W and pulse duration of 100 μs) and G9 (pulsed mode, duty cycle = 50%, average power = 1.5W, peak = 3.6W and pulse duration = 1 ms) producing the largest damage areas (median 1.93 and 1.97 mm2 , respectively). In the multiple comparison, controlling the level of global significance, G3 presented a median area of thermal damage significantly smaller than those of G7 (p = 0.013) and G9 (p = 0.036). There were no statistically significant differences in the depth of thermal damage between the groups (p = 0.12). The median excision times of G1 (scalpel) and G10 (super pulsed) were significantly shorter than those found in the micro pulsed diode laser groups (G1 = 50; G10 = 69; G2 to G9 ranged from 142 to 238 seconds; p < 0.001). There was a direct correlation between the depth and area of thermal damage, but no correlation was found between the excision time and thermal damage. The use of the micro pulsed diode laser in continuous mode with average power = 1.5 W produced biopsies with the smallest area of thermal damage and greater tissue integrity, while the use of the super pulsed diode laser (average power = 3.2W, peak power = 80W, pulse duration from 10 μs to 100 ms) allowed faster excisions. Area and depth of thermal damage correlated directly. In clinical practice, the micro pulsed diode laser should be considered in continuous mode, at 1.5 W output power with 1.8 W peak power as the best option when aiming to achieve maximum tissue integrity. Whereas the use of super pulsed diode laser with output power = 3.2W, peak power = 80W, pulse duration from 10 μs to 100 ms, produced the best relationship between thermal damage and excision time, and is recommended when practical necessity requires rapid excisions with reasonable tissue integrity. The use of micro pulsed diode laser in pulsed emission mode with high peak power and long pulse duration should be avoided when performing oral biopsies so that tissue integrity is not compromised and hinders the histopathological analysis of the lesions.

    Palavras-Chave: diode-pumped solid state lasers; thermionic diodes; semiconductor diodes; electromagnetic pulses; internal electromagnetic pulses; pulse techniques; excision repair; animal tissues; oral cavity; damage; diagnostic techniques; biopsy; temperature dependence; thermal efficiency; penetration depth; depth dose distributions; optical depth curve; histological techniques; optical microscopy

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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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  • IPEN-DOC 28112

    TABACOW, FABIO B.D. ; ZUFFI, ARMANDO V.F. ; MALDONADO, EDISON P.; SAMAD, RICARDO E. ; VIEIRA JUNIOR, NILSON D. . Theoretical and experimental study of supersonic gas jet targets for laser wakefield acceleration. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, May 31 - June 2, 2021, Online. Proceedings... Piscataway, NJ, USA: IEEE, 2021. DOI: 10.1109/SBFOTONIOPC50774.2021.9461936

    Abstract: This work reports a theoretical and experimental study of supersonic gas jets to be used as targets in laser wakefield acceleration. A comparison between theoretical and experimental results ismade in order to estimate the results of a de Laval nozzle manufactured in our laboratory, used to produce a N2 gas target. The comparison between the results shows that Computational Fluid Dynamicssimulations are able todescribe the phenomena of the supersonic gas jet.

    Palavras-Chave: interferometry; acceleration; wakefield accelerators; computer calculations; fluid mechanics; nozzles; supersonic flow

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  • IPEN-DOC 28575

    MELO, PEDRO B. dos S.; CARDOSO, ELBIS S.; SAMAD, RICARDO E. ; MOTTA, CLAUDIO C.. Theoretical analysis of the influence of Photodarkening on the gain of a YDCFL. In: SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE, October 24-27, 2021, Fortaleza, CE. Proceedings... Danvers, MA, USA: Institute of Electrical and Electronic Engineers (IEEE), 2021. DOI: 10.1109/IMOC53012.2021.9624806

    Abstract: An analytical formulation was developed to study the influence of the Photodarkening (PD) on the gain behavior of a ytterbium doped double-clad fiber laser (YDCFL). To formalize the modeling, the fundamental equations that describe the continuous wave laser in the steady state tandem pumping regime were employed. It was possible to observe the dependence of the YDCFL signal gain with temperature, absorption and emission cross sections, and with the higher level population density. Since the gain is related to these laser parameters, it may change significantly with increasing temperature in the fiber due to the PD effect.

    Palavras-Chave: doped materials; ytterbium ions; optical fibers; gain

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  • IPEN-DOC 28574

    MENDES, LUCAS S.; NACARATTI, DAVI P.; SAMAD, RICARDO E. ; MOTTA, CLAUDIO C.. Theoretical analysis of the efficiency of a 7 × 1 end-pumped power combiner. In: SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE, October 24-27, 2021, Fortaleza, CE. Proceedings... Danvers, MA, USA: Institute of Electrical and Electronic Engineers (IEEE), 2021. DOI: 10.1109/IMOC53012.2021.9624827

    Abstract: An analytical formulation for the power transmission efficiency of a 7 × 1 end-pumped combiner has been developed and is reported in this paper. The formulation is supported by the Coupled-Mode Theory, and considers the modal coupling in a straight, circular cross section, optical fiber whose radius decreases monotonically. Within this scope, the power efficiency for each input fiber is determined for different tapers shapes.

    Palavras-Chave: optical fibers; coupling; power transmission; pumping

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  • IPEN-DOC 28073

    FREITAS, LUCAS F. ; FERREIRA, ARYEL H. ; THIPE, VELAPHI C. ; VARCA, GUSTAVO H.C. ; LIMA, CAROLINE S.A. ; BATISTA, JORGE G.S. ; RIELLO, FABIANE N. ; NOGUEIRA, KAMILA ; CRUZ, CASSIA P.C. ; MENDES, GIOVANNA O.A. ; RODRIGUES, ADRIANA S. ; SOUSA, THAYNA S. ; ALVES, VICTORIA M. ; LUGAO, ADEMAR B. . The state of the art of theranostic nanomaterials for lung, breast, and prostate cancers. Nanomaterials, v. 11, n. 10, p. 1-31, 2021. DOI: 10.3390/nano11102579

    Abstract: The synthesis and engineering of nanomaterials offer more robust systems for the treatment of cancer, with technologies that combine therapy with imaging diagnostic tools in the so‐called nanotheranostics. Among the most studied systems, there are quantum dots, liposomes, polymeric nanoparticles, inorganic nanoparticles, magnetic nanoparticles, dendrimers, and gold nanoparticles. Most of the advantages of nanomaterials over the classic anticancer therapies come from their optimal size, which prevents the elimination by the kidneys and enhances their permeation in the tumor due to the abnormal blood vessels present in cancer tissues. Furthermore, the drug delivery and the contrast efficiency for imaging are enhanced, especially due to the increased surface area and the selective accumulation in the desired tissues. This property leads to the reduced drug dose necessary to exert the desired effect and for a longer action within the tumor. Finally, they are made so that there is no degradation into toxic byproducts and have a lower immune response triggering. In this article, we intend to review and discuss the state‐of‐the‐art regarding the use of nanomaterials as therapeutic and diagnostic tools for lung, breast, and prostate cancer, as they are among the most prevalent worldwide.

    Palavras-Chave: nanomaterials; nanotechnology; neoplasms; theranostics

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  • 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

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