INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES
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Navegação por Agências de fomento "Instituto de Pesquisas Energéticas e Nucleares (IPEN)"

Navegação por Agências de fomento "Instituto de Pesquisas Energéticas e Nucleares (IPEN)"

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  • IPEN-DOC 28682

    SILVA, FLAVIA R.O. ; LIMA, NELSON B. ; BELLINI, MARIA H. ; TEIXEIRA, LUIZ F.S. ; DU, ERIC Y.; JAMSHIDI, NILOUFAR; GOODING, JUSTIN; MARTIN, ADAM D.; MACMILLAN, ALEXANDER; MARQUIS, CHRISTOPHER P.; THORDARSON, PALL. Lanthanide-based β-tricalcium phosphate upconversion nanoparticles as an effective theranostic nonviral vectors for image-guided gene therapy. Nanotheranostics, v. 6, n. 3, p. 306-321, 2022. DOI: 10.7150/ntno.68789

    Abstract: Lanthanide-based beta-tricalcium phosphate (β-TCP) upconversion nanoparticles are exploited as a non-viral vector for imaging guided-gene therapy by virtue of their unique optical properties and multi-modality imaging ability, high transfection efficiency, high biocompatibility, dispersibility, simplicity of synthesis and surface modification. Ytterbium and thulium-doped β-TCP nanoparticles (βTCPYbTm) are synthesized via co-precipitation method, coated with polyethylenimine (PEI) and functionalized with a nuclear-targeting peptide (TAT). Further, in vitro studies revealed that the nanotheranostic carriers are able to transfect cells with the plasmid eGFP at a high efficiency, with approximately 60% of total cells producing the fluorescent green protein. The optimized protocol developed comprises the most efficient βTCPYbTm/PEI configuration, the amount and the order of assembly of βTCPYbTm:PEI, TAT, plasmid DNA and the culturing conditions. With having excellent dispersibility and high chemical affinity toward nucleic acid, calcium ions released from βTCPYbTm:PEI nanoparticles can participate in delivering nucleic acids and other therapeutic molecules, overcoming the nuclear barriers and improving the transfection efficacy. Equally important, the feasibility of the upconversion multifunctional nanovector to serve as an effective contrast agent for imaging modality, capable of converting low-energy light to higher-energy photons via a multi-photons mechanism, endowing greater unique luminescent properties, was successfully demonstrated.

    Palavras-Chave: gene therapy; polyethylenes; nanoparticles; calcium phosphates

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  • IPEN-DOC 29041

    BURIMOVA, ANASTASIA ; CARBONARI, ARTUR W. ; LIMA, NICOLE P. de ; MIRANDA FILHO, ARNALDO A. ; SOUZA, ALEXANDRE P. dos S. ; SALES, TATIANE da S.N. ; FERREIRA, WANDERSON L. ; PEREIRA, LUCIANO F.D. ; CORREA, BRUNO S. ; SAXENA, RAJENDRA N. . Local crystalline structure of doped semiconductor oxides characterized by perturbed angular correlations: experimental and theoretical insights. Crystals, v. 12, n. 9, p. 1-15, 2022. DOI: 10.3390/cryst12091204

    Abstract: Doping semiconductor oxides with trace amounts of non-native elements can improve their properties such as bandgap and conductivity. The lack of local techniques makes the precise characterization of these materials difficult. Among the few techniques capable of providing local characterization, those based on hyperfine interactions at probe nuclei have the advantage of being well established, probing the material homogeneously and completely, thus investigating different regions of material. Some of these techniques are also quite sensitive even at extremely low dopant concentrations. The perturbed angular correlation technique, combined with first-principles calculations, has recently been shown to be a powerful method for characterizing doped semiconductor oxides. In this paper, we present a brief review of the unique information extracted from the semiconductor investigation with such a complex approach, including semiconductor oxides doped with cadmium and other elements. A strong relationship between the local environment, including electronic structure, and the nature of the dopant and the native element of the doped oxides is also shown.

    Palavras-Chave: crystal doping; semiconductor materials; oxides; hyperfine structure; interactions; perturbed angular correlation

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  • IPEN-DOC 29134

    PASCOALINO, K. ; CAMARGO, F. ; GONCALVES, J.A.C. ; BUENO, C.C. . Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry. Brazilian Journal of Radiation Sciences, v. 10, n. 3B, p. 1-9, 2022. DOI: 10.15392/2319-0612.2022.1789

    Abstract: In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on variations in the path lengths of alpha particles through the insensitive layer and the correspondent energy losses when they impinge on a diode surface at different angles. Therefore, the pulse heights of these alpha particles, closely related to the energies deposited in the active volume of the diode, also depend on their incident angle. So, the difference between the pulse height of alpha particles perpendicularly incident on the diode surface and at any incident angle enables the insensitive layer thickness to be assessed. The result obtained (711  23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the investigated diode is suitable for high resolution charged particle spectrometry.

    Palavras-Chave: alpha spectroscopy; dosimetry; energy losses; layers; photodiodes; radiation protection; silicon; thickness

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  • IPEN-DOC 30048

    SILVA, FLAVIA R.O. ; PASCOAL, DIEGO R.C. ; BERECZKI, ALLAN ; SIPERT, CARLA R.; BRAGA, ROBERTO R.; BELLINI, MARIA H. ; SILVA, LUIS F.T. ; FREITAS, ANDERSON Z. ; WETTER, NIKLAUS U. . Micro-Raman spectroscopy identification of hydroxyapatite in dental pulp stem cells. In: CONFERENCE ON LASERS AND ELECTRO-OPTICS: APPLICATIONS AND TECHNOLOGY, May 7-12, 2023, San Jose, CA, USA. Proceedings... Washington, DC, USA: Optica Publishing Group, 2023. DOI: 10.1364/CLEO_AT.2023.AM4Q.6

    Abstract: Cell differentiation using calcium phosphate nanoparticles was studied. The hydroxyapatite was internalized in human dental pulp stem cells and characterized by Raman spectroscopy. Raman spectra showed the hydroxyapatite distribution in nanoparticles nodules in the cells.

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  • IPEN-DOC 30026

    GOMES, ANTONIO A. ; NARIO, ARIAN P. ; LAPOLLI, ANDRE L. ; LANDULFO, EDUARDO ; BERNARDES, EMERSON S. ; ROSSI, WAGNER de . Microfluídica, uma tecnologia aplicada à concentração de 18F para produção de radiofármacos. In: CONGRESSO BRASILEIRO DE MEDICINA NUCLEAR, 37., 21-23 de setembro, 2023, Porto de Galinhas, PE. Resumo... São Paulo, SP: Sociedade Brasileira de Medicina Nuclear - SBMN, 2023.

    Abstract: Introdução. O uso de radiofármacos marcados com 18F para o diagnóstico clínico por imagem PET (tomografia por emissão de pósitrons) de diversas doenças tem aumentado consideravelmente. O maior radiofármaco aplicado a diagnósticos com PET é o [18F]-2-desoxi-2-fluoro-D-glicose (FDG) e a sua preparação requer a utilização de equipamentos especializados (e caros) para proteger o farmacêutico que o prepara. Assim, à medida que a demanda de radiofármacos PET aumentar, colocará uma pressão significativa nas instalações de produção de traçadores PET, a qual necessitará de investimento em novas tecnologias de produção de radiofármacos. Uma tecnologia chave desenvolvida nos últimos tempos tem sido o uso de sistemas microfluídicos. Os dispositivos microfluídicos oferecem muitas vantagens para a síntese de radiofármacos de curta duração (por exemplo, 18F)tais como: reações mais rápidas, transferência de calor eficiente, alta relação superfície – volume e rendimentos mais elevados. Embora os sistemas microfluídicos estudados para radiofármacos existam há quase 20 anos, no Brasil, até onde sabemos, esta tecnologia e estudo é inédita. Objetivos. Apresentar os primeiros resultados no desenvolvimento de um chip microfluídico para uma “microcoluna” destinada ao processo de retenção e eluição de 18F. Metodologia. A microcoluna foi usinada em vidro óptico de borosilicato – BK7 utilizando a técnica de ablação com laser de pulsos ultracurtos. Após a microusinagem, a microcoluna é preenchida com a mesma resina utilizada no cartucho convencional de síntese “Sep-Pak Accell Plus QMA Plus Light” da fabricante Waters™. Ambas são posteriormente submetidas a testes de desempenho comparativos de eficiência na fase de retenção e eluição de 18F. Resultados. Foram realizados 4 testes comparativos para ambas as fases (primeira etapa da síntese de 18F-FDG), com atividades (1,5 ± 0,3 mCi e 248 ± 11 mCi; “n = 2”). Os resultados demostraram que a eficiência da microcoluna é equivalente à da coluna convencional (QMA Plus Light) na fase de retenção (99,3% ± 0,67 vs99,6% ± 0,32). No entanto, na fase de eluição de 18F, houve uma diferença significativa entre ambas (99,93% ±0,18 vs 77,38% ± 15,54), destacando a grande vantagem da microcoluna. Conclusão. A integração do cartucho de troca iônica em um chip, com a técnica de ablação com laser de pulso ultracurto, abre as portas para chips de radiofarmácia menores e mais eficientes para a produção de 18F-FDG e outros compostos. Os resultados experimentais inéditos no Brasil demonstram que as etapas iniciais da produção de doses prontas para humanos (pré-concentração de flúor) podem ser realizadas com uma eficiência superior nos parâmetros de eluição do 18Fem comparação a síntese com cartucho convencional.

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  • IPEN-DOC 27867

    BRAGUIN, L.N.M. ; SILVA, C.A.J. ; COSTA, I. ; SAIKI, M. . Neutron activation analysis of austenitic stainless steel used as biomaterial. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-16, 2021. DOI: 10.15392/bjrs.v9i1A.1337

    Abstract: Austenitic stainless steel alloys, mainly those produced according to ISO 5832-1, have received much attention due to their promising characteristics to be used as biomaterials. The aim of this study was to establish the proper conditions of neutron activation analysis (NAA) in order to determine chemical elements in a sample of ISO 5832-1 stainless steel. These determinations are of great interest for further evaluation of its corrosion resistance and of cytotoxicity of corrosion products. For the analyses, chips of ISO 5832-1 austenitic stainless steel were obtained. Aliquots of this material were weighed in polyethylene involucres and irradiated together with synthetic element standards at the IEA-R1 nuclear research reactor. Short and long irradiations were carried out using thermal neutron flux of about 4.5 x 1012 n cm-2 s-1. Quality control of the results was performed by analyzing two certified reference materials (CRMs). The elements concentrations of Cr, Cu, Mn, Mo and Ni obtained in the ISO 5832-1 austenitic alloy are within the specification values of this material. Besides, the elements As, Co, V and W were determined in this alloy. The sensitivity of the technique was verified by the determination of detection and quantification limits. In the case of CRMs, their results presented precision and accuracy for most of elements with relative standard deviations and relative errors lower than 15 %. Results obtained in this study demonstrated the viability of applying NAA in the analysis of the ISO 5832-1 stainless steel alloy.

    Palavras-Chave: austenitic steels; biological materials; elements; iear-1 reactor; irradiation; neutron activation analysis; quality control; stainless steels; thermal neutrons

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  • IPEN-DOC 29851

    TEIXEIRA, LUIZ F.S. ; BELLINI, MARIA H. . NF-ĸΒ1 knockout reduces IL6 expression under hypoxia in renal cell carcinoma. Cellular and Molecular Biology, v. 69, n. 6, p. 8-14, 2023. DOI: 10.14715/cmb/2023.69.6.2

    Abstract: Renal cell carcinoma (RCC) is the most common adult renal epithelial cancer, accounting for more than 90% of all renal neoplasms. Clear cell RCC (ccRCC) is the most common subtype of RCC. Most patients with ccRCC have a mutation in the von Hippel-Lindau (VHL) tumor suppressor gene, which encodes a protein that downregulates various intracellular proteins, including hypoxia-inducible factor (HIF). Many molecules have been identified to be responsible for the aggressive phenotype of ccRCC, including the transcription factor nuclear factor kappa B (NF-кB). The increase in NF-кB activity observed in RCC is correlated with an increase in angiogenesis markers, such as interleukin 6 (IL-6). In recent years, several groups have demonstrated the functional role of NF-кB1 in RCC tumorigenicity. Herein, we used the CRISPR/Cas-9 technique to obtain an NF-кB1 knockout-human renal adenocarcinoma cell line. Expression of IL-6 at the mRNA and protein levels was analyzed under normoxia and hypoxia by real time-polymerase chain reaction and multiplex assay, respectively. The CRISPR/Cas9 technique was effective in producing 786-0 knockout cells for NF-κB1 (p105/p50), as confirmed by western blot analysis. Suppression of p50 expression in 786-0 single guide RNA (sg)1, 786-0 sg2 and 786-0 sg3 cells downregulated IL-6 mRNA and protein expression under normoxia and hypoxia. The observed decrease in the differential expression of IL-6 in hypoxia/normoxia is suggestive of a change in cellular responsiveness to hypoxia with respect to IL-6.

    Palavras-Chave: carcinomas; neoplasms; lymphokines; anoxia; tumor cells; kidneys

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  • IPEN-DOC 28666

    BUENO, C.C. ; CAMARGO, F. ; GONCALVES, J.A.C. ; PASCOALINO, K. ; MANGIAROTTI, A.; TUOMINEN, E.; HARKONEN, J.. Performance characterization of dosimeters based on radiation-hard silicon diodes in gamma radiation processing. Frontiers in Sensors, v. 3, p. 1-11, 2022. DOI: 10.3389/fsens.2022.770482

    Abstract: The dosimetric response of silicon diodes produced with distinct engineering technologies, Magnetic Czochralski (MCz), and standard Float Zone (Fz), has been investigated, aiming at their use for online dosimeters in gamma radiation processing applications. The p+-n-n+ junction diodes, 300 µm thick with an active area of 25 mm2, are operated as online radiation dosimeters in the short-circuit current mode. In this case, the key dosimetric quantity is the dose rate, which is correlated with the output current from the diode subjected to radiation. Thus, the dose is obtained offline by the integration of the corresponding current signal. The irradiations are performed with an industrial Gammacell 60Co facility at 2.3–2.44 kGy/h covering doses up to 275 kGy. Under continuous irradiation, both diodes delivered current signals whose intensities decreased with accumulated doses. Mitigation of this decay has been accomplished by pre-irradiating the devices to 700 kGy. Polynomial functions best represent the dose responses for either pristine or preirradiated diodes. The relevant dosimetric parameters as response stability, charge sensitivity, and repeatability of current signals (<5%) reveal the better performance of the MCz diode. It is important to note that the whole dataset fully complies with the international standard protocols for routine dosimeters in radiation processing dosimetry. Regarding radiation damage, which in unbiased diodes manifests primarily in the decay of current sensitivity, the results also showed greater tolerance of the MCz diode. Based on these studies, large availability, and better cost-effectiveness, it is possible to endorse the potential use of MCz devices as online routine dosimeters in radiation processing applications. However, the data reproducibility with the accumulated dose, the dose lifespan, and the effect of the irradiation conditions (e.g., temperature, relative humidity, and dose fractionating) remain to be investigated. Works in this direction are currently in progress.

    Palavras-Chave: silicon diodes; radiations; processing; czochralski method; gamma dosimetry

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  • IPEN-DOC 27769

    SUZUKI, MIRIAM F. ; ALMEIDA, LARISSA A. ; POMIN, STEPHANIE A. ; SILVA, FELIPE D. ; FREIRE, RENAN P. ; OLIVEIRA, JOAO E. ; AFFONSO, REGINA ; SOARES, CARLOS R.J. ; BARTOLINI, PAOLO . Periplasmic synthesis and purification of the human prolactin antagonist Δ1‑11‑G129R‑hPRL. AMB Express, v. 11, n. 1, p. 1-12, 2021. DOI: 10.1186/s13568-021-01209-5

    Abstract: The human prolactin antagonist Δ1-11-G129R-hPRL is a 21.9 kDa recombinant protein with 188 amino acids that downregulates the proliferation of a variety of cells expressing prolactin receptors. Periplasmic expression of recombinant proteins in E. coli has been considered an option for obtaining a soluble and correctly folded protein, as an alternative to cytoplasmic production. The aim of this work was, therefore, to synthesize for the first time, the Δ1-11-G129R-hPRL antagonist, testing different activation temperatures and purifying it by classical chromatographic techniques. E. coli BL21(DE3) strain was transformed with a plasmid based on the pET25b( +) vector, DsbA signal sequence and the antagonist cDNA sequence. Different doses of IPTG were added, activating under different temperatures, and extracting the periplasmic fluid via osmotic shock. The best conditions were achieved by activating at 35 °C for 5 h using 0.4 mM IPTG, which gave a specific expression of 0.157 ± 0.015 μg/mL/A600 at a final optical density of 3.43 ± 0.13 A600. Purification was carried out by nickel-affinity chromatography followed by size-exclusion chromatography, quantification being performed via high-performance size-exclusion chromatography (HPSEC). The prolactin antagonist was characterized by SDS-PAGE, Western blotting, reversed-phase high-performance liquid chromatography (RP-HPLC) and MALDI-TOF–MS. The final product presented > 95% purity and its antagonistic effects were evaluated in vitro in view of potential clinical applications, including inhibition of the proliferation of cancer cells overexpressing the prolactin receptor and specific antidiabetic properties, taking also advantage of the fact that this antagonist was obtained in a soluble and correctly folded form and without an initial methionine.

    Palavras-Chave: lth; peptides; chromatography; neoplasms; purification; mass spectra; bioassay; plasma

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  • IPEN-DOC 30185

    DIPOLD, JESSICA ; BORDON, CAMILA D.S.; MAGALHAES, EVELLYN S.; KASSAB, LUCIANA R.P.; JIMENEZ-VILLAR, ERNESTO; WETTER, NIKLAUS U. . Random laser emission in Nd3+ doped tellurite glass. In: INTERNATIONAL CONFERENCE ON OPTICAL MEMS AND NANOPHOTONICS; SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, July 31 - August 3, 2023, Campinas, SP. Proceedings... Piscataway, NJ, USA: IEEE, 2023. DOI: 10.1109/OMN/SBFOTONIOPC58971.2023.10230929

    Abstract: Random lasers are easier and cheaper to manufacture than regular ones, being made of several materials such as polymers, powders or dyes. Glass random lasers have been rarely studied due to their inhomogeneous broadened emission and low damage threshold. Here, we study Nd 3 +doped Te0 2 -ZnO-Al 2 0 3 glasses with different concentrations of rare-earth doping (4 wt.%, 8 wt.% and 16 wt.%). Emission intensity per pump fluence and fluorescence decay time measurements showed the potential of these glasses for random laser applications in the near-infrared region.

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  • IPEN-DOC 30193

    WETTER, NIKLAUS U. ; VIEIRA, RENATO J.R. ; SILVA, DANILO M. da ; JORGE, KELLY C. ; JIMENEZ-VILLAR, ERNESTO ; GIEHL, JULIA M. ; MIRANDA, ADRIANA R. de ; DIPOLD, JESSICA . Random lasers: review of research activities at IPEN. In: INTERNATIONAL CONFERENCE ON OPTICAL MEMS AND NANOPHOTONICS; SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, July 31 - August 3, 2023, Campinas, SP. Proceedings... Piscataway, NJ, USA: IEEE, 2023. DOI: 10.1109/OMN/SBFotonIOPC58971.2023.10230975

    Abstract: Random lasers offer advantages such as low-cost fabrication and robustness in harsh environments and have applications in sensing, imaging, communications, and security. Our current research focuses on advanced materials, active control techniques, integration with other photonic structures, and exploration of Anderson localization and polydisperse effects. Coherent feedback in cavity-enhanced random lasers is discussed as means to achieve specific emission characteristics, and emission at 1300 nm is shown for the first time.

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  • IPEN-DOC 27413

    SILVA, PAULA M. da ; SERNA, MARILENE M. ; GALEGO, EGUIBERTO ; FARIA, RUBENS N. . Study of supercapacitors for use in dye sensitized solar cells. Materials Science Forum, v. 1012, p. 114-118, 2020. DOI: 10.4028/www.scientific.net/MSF.1012.114

    Abstract: The storage of energy generated by photovoltaic system is one problem of it. In this aspect, integrated energy conversion and storage systems, IECSS, using supercapacitors are presented as a solution. Dye sensitized solar cell becomes a main candidate for use in IECSS due its variety of applications. Recent studies shown that zinc oxide (ZnO) is a natural candidate for use in solar cells and supercapacitor due to its high energy density of the order 650 A g-1. The aims of this paper were: i) the study of the influence of the morfology of nanostructured ZnO nanoparticles obtained by the hydrothermal method using distincts complexing agents: etylenediaminetetraacetic acid (EDTA); hexamethyltetramine (HMT) and diaminometanal (urea), besides commercial ZnO; ii) study of the ZnO and activated carbon at ratio X:Y of 10:90, 20:80 and 30:70 in proportion of mass (%) in the preparation of electrodes. The commercial ZnO, which presents particles with spherical and porous morphology, presented the best capacitance result 8.38 Fg-1 at 10:90 ratio, that demonstrates the ZnO is an excellent candidate for material for supercapacitor coupled with dye solar cell.

    Palavras-Chave: capacitive energy storage equipment; capacitors; energy storage; zinc oxides; solar cells; sensitizers; electrodes; hydrothermal systems

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  • IPEN-DOC 30037

    BERECZKI, ALLAN ; DIPOLD, JESSICA ; FREITAS, ANDERSON Z. ; WETTER, NIKLAUS U. . Sub-10 nm nanoparticle detection using multi-technique-based micro-raman spectroscopy. Polymers, v. 15, n. 24, p. 1-17, 2023. DOI: 10.3390/polym15244644

    Abstract: Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nanosized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO2 nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force Microscopy

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  • IPEN-DOC 28693

    SOUZA, CARLA D. de ; BARBEZAN, ANGELICA B. ; ROSERO, WILMMER A.A. ; SANTOS, SOFIA N. dos ; CARVALHO, DIEGO V. de S. ; ZEITUNI, CARLOS A. ; BERNARDES, EMERSON S. ; VIEIRA, DANIEL P. ; SPENCER, PATRICK J. ; RIBEIRO, MARTHA S. ; ROSTELATO, MARIA E.C.M. . Synthesis, in vitro testing, and biodistribution of surfactant-free radioactive nanoparticles for cancer treatment. Nanomaterials, v. 12, n. 2, p. 1-13, 2022. DOI: 10.3390/nano12020187

    Abstract: New forms of cancer treatment, which are effective, have simple manufacturing processes, and easily transportable, are of the utmost necessity. In this work, a methodology for the synthesis of radioactive Gold-198 nanoparticles without the use of surfactants was described. The nuclear activated Gold-198 foils were transformed into H198AuCl4 by dissolution using aqua regia, following a set of steps in a specially designed leak-tight setup. Gold-198 nanoparticles were synthesized using a citrate reduction stabilized with PEG. In addition, TEM results for the non-radioactive product presented an average size of 11.0 nm. The DLS and results for the radioactive 198AuNPs presented an average size of 8.7 nm. Moreover, the DLS results for the PEG-198AuNPs presented a 32.6 nm average size. Cell line tests showed no cytotoxic effect in any period and the concentrations were evaluated. Furthermore, in vivo testing showed a high biological uptake in the tumor and a cancer growth arrest.

    Palavras-Chave: radioactivity; nanoparticles; brachytherapy; neoplasms; testing; in vivo; in vitro; gold 198; distribution

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  • 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

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  • IPEN-DOC 29033

    GONCALVES, J.A.C. ; SOMESSARI, E.S.R. ; SOMESSARI, S.L. ; BUENO, C.C. . Transit dose measurements using alanine and diode-based dosimeters. Brazilian Journal of Radiation Sciences, v. 10, n. 2A, p. 1-9, 2022. DOI: 10.15392/bjrs.v10i2A.1828

    Abstract: The growing interest in low-dose (< 100 Gy) radiation processing applications has raised concerns about accurately measuring the absorbed dose in irradiated materials. Depending on the irradiator design, the transit time due to the radioactive source movement (or the product itself) until the stable irradiation position might affect the predicted absorbed dose. This work aims to evaluate the transit dose in a 60Co Gammacell 220-Nordion irradiator, which has radioactive sources settled at the bottom of a lead shielding. When the facility is on, the product and the dosimeter are mechanically guided down to the irradiation position, and hereafter the selected exposure time starts to be counted. At the end of irradiation, both product and dosimeter rise to the initial position enabling them to be gathered by the operator. The product is continuously irradiated at different dose rates during its fall and rise movement, preventing the transit dose from being obtained straightforward. The experimental approach adopted is to assess the transit time, and thus the transit dose, using an online diode-based dosimetry system previously calibrated against reference standard alanine dosimeters. The agreement between the transit doses attained with the diode (0.41 ± 0.02) Gy and alanine (0.38 ± 0.01) Gy validates the method herein proposed.

    Palavras-Chave: absorbed radiation doses; alanines; cobalt 60; dose rates; dosemeters; dose-response relationships; radiation monitoring

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  • IPEN-DOC 30036

    MUNOZ, PATRICIO; ILAVSKY, JAN; NEWVILLE, MATTHEW; WETTER, NIKLAUS U. ; LOURENÇO, RAFAEL A.; ANDRADE, MARCELO B. de; MARTINS, TEREZA S.; DIPOLD, JESSICA ; FREITAS, ANDERSON Z. ; SILVA, LUIS C.C. da; OLIVEIRA, CRISTIANO L.P.. (U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation. Journal of Applied Crystallography, v. 56, Part: 6, p. 1692-1706, 2023. DOI: 10.1107/S1600576723008889

    Abstract: This study characterizes the microstructure and mineralogy of 132 (ODP sample), 1000 and 1880 million-year-old chert samples. By using ultra-smallangle X-ray scattering (USAXS), wide-angle X-ray scattering and other techniques, the preservation of organic matter (OM) in these samples is studied. The scarce microstructural data reported on chert contrast with many studies addressing porosity evolution in other sedimentary rocks. The aim of this work is to solve the distribution of OM and silica in chert by characterizing samples before and after combustion to pinpoint the OM distribution inside the porous silica matrix. The samples are predominantly composed of alpha quartz and show increasing crystallite sizes up to 33 5 nm (1 standard deviation or SD). In older samples, low water abundances (0.03%) suggest progressive dehydration. (U)SAXS data reveal a porous matrix that evolves over geological time, including, from younger to older samples, (1) a decreasing pore volume down to 1%, (2) greater pore sizes hosting OM, (3) decreasing specific surface area values from younger (9.3 0.1 m2 g 1 ) to older samples (0.63 0.07 m2 g 1 , 1 SD) and (4) a lower background intensity correlated to decreasing hydrogen abundances. The pore-volume distributions (PVDs) show that pores ranging from 4 to 100 nm accumulate the greater volume fraction of OM. Raman data show aromatic organic clusters up to 20 nm in older samples. Raman and PVD data suggest that OM is located mostly in mesopores. Observed structural changes, silica–OM interactions and the hydrophobicity of the OM could explain the OM preservation in chert.

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A pesquisa no RD utiliza os recursos de busca da maioria das bases de dados. No entanto algumas dicas podem auxiliar para obter um resultado mais pertinente.

✔ 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

Título: loss of coolant

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 .

✔ Ao efetuar a busca por um autor o RD apresentará uma relação de todos os trabalhos depositados no RD. No lado direito da tela são apresentados os coautores com o número de trabalhos produzidos em conjunto bem como os assuntos abordados e os respectivos anos de publicação agrupados.

✔ O RD disponibiliza um quadro estatístico de produtividade, onde é possível visualizar o número dos trabalhos agrupados por tipo de coleção, a medida que estão sendo depositados no RD.

✔ 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.

✔ Na página do pesquisador, é possível verificar, as variações do nome, a relação de todos os trabalhos com texto completo bem como um quadro resumo numérico; há links para o Currículo Lattes e o Google Acadêmico ( quando esse for informado).

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.