Navegação Periódicos - Artigos por ano de publicação "2017"

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  • IPEN-DOC 23753

    LEVY, DENISE ; VILLAVICENCIO, ANNA L.C.H. . Web-based tools to increase public understanding of nuclear technology and food irradiation. International Journal of Social, Behavioral, Educational, Economic, Business and Industrial Engineering; International Scholarly and Scientific Research & Innovation, v. 11, n. 1, p. 70-74, 2017.

    Abstract: Food irradiation is a processing and preservation technique to eliminate insects and parasites and reduce diseasecausing microorganisms. Moreover, the process helps to inhibit sprouting and delay ripening, extending fresh fruits and vegetables shelf-life. Nevertheless, most Brazilian consumers seem to misunderstand the difference between irradiated food and radioactive food and the general public has major concerns about the negative health effects and environmental contamination. Society´s judgment and decision making are directly linked to perceived benefits and risks. The web-based project entitled ‘Scientific information about food irradiation: Internet as a tool to approach science and society’ was created by the Nuclear and Energetic Research Institute (IPEN), in order to offer an interdisciplinary approach to science education, integrating economic, ethical, social and political aspects of food irradiation. This project takes into account that, misinformation and unfounded preconceived ideas impact heavily on the acceptance of irradiated food and purchase intention by the Brazilian consumer. Taking advantage of the potential value of the Internet to enhance communication and education among general public, a research study was carried out regarding the possibilities and trends of Information and Communication Technologies among the Brazilian population. The content includes concepts, definitions and Frequently Asked Questions (FAQ) about processes, safety, advantages, limitations and the possibilities of food irradiation, including health issues, as well as its impacts on the environment. The project counts on eight selfinstructional interactive web courses, situating scientific content in relevant social contexts in order to encourage self-learning and further reflections. Communication is a must to improve public understanding of science. The use of information technology for quality scientific divulgation shall contribute greatly to provide information throughout the country, spreading information to as many people as possible, minimizing geographic distances and stimulating communication and development.

    Palavras-Chave: food processing; irradiation; learning; educational tools; educational facilities; nuclear energy; nuclear engineering; reactor technology; scientific personnel

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  • IPEN-DOC 23779

    LEVY, DENISE ; SORDI, GIAN M.A.A. . Web-based instructional program to improve professional development: recommendations and standards for radioactive facilities in Brazil. International Journal of Social, Behavioral, Educational, Economic, Business and Industrial Engineering; International Scholarly and Scientific Research & Innovation, v. 11, n. 1, p. 75-80, 2017.

    Abstract: This web based project focuses on continuing corporate education and improving workers' skills in Brazilian radioactive facilities throughout the country. The potential of Information and Communication Technologies (ICTs) shall contribute to improve the global communication in this very large country, where it is a strong challenge to ensure high quality professional information to as many people as possible. The main objective of this system is to provide Brazilian radioactive facilities a complete web-based repository - in Portuguese - for research, consultation and information, offering conditions for learning and improving professional and personal skills. UNIPRORAD is a web based system to offer unified programs and inter-related information about radiological protection programs. The content includes the best practices for radioactive facilities in order to meet both national standards and international recommendations published by different organizations over the past decades: International Commission on Radiological Protection (ICRP), International Atomic Energy Agency (IAEA) and National Nuclear Energy Commission (CNEN). The website counts on concepts, definitions and theory about optimization and ionizing radiation monitoring procedures. Moreover, the content presents further discussions related to some national and international recommendations, such as potential exposure, which is currently one of the most important research fields in radiological protection. Only two publications of ICRP develop expressively the issue and there is still a lack of knowledge of fail probabilities, for there are still uncertainties to find effective paths to quantify probabilistically the occurrence of potential exposures and the probabilities to reach a certain level of dose. To respond to this challenge, this project discusses and introduces potential exposures in a more quantitative way than national and international recommendations. Articulating ICRP and AIEA valid recommendations and official reports, in addition to scientific papers published in major international congresses, the website discusses and suggests a number of effective actions towards safety which can be incorporated into labor practice. The WEB platform was created according to corporate public needs, taking into account the development of a robust but flexible system, which can be easily adapted to future demands. ICTs provide a vast array of new communication capabilities and allow to spread information to as many people as possible at low costs and high quality communication. This initiative shall provide opportunities for employees to increase professional skills, stimulating development in this large country where it is an enormous challenge to ensure effective and updated information to geographically distant facilities, minimizing costs and optimizing results.

    Palavras-Chave: nuclear facilities; radioactive waste facilities; education; learning; websites; scientific personnel; standards; educational facilities

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  • IPEN-DOC 24342

    GARCIA, VANESSA S.G. ; MATSUSHITA, EDUARDO T.D.; MESQUITA, LETICIA C.A. ; FAVARO, DEBORAH I.T. ; BORRELY, SUELI I. . Water quality and ecotoxicity assessment in surface waters from Cubatão River and surroundings, São Paulo, Brazil. Journal of Water Resource and Protection, v. 09, n. 12, p. 1510-1525, 2017. DOI: 10.4236/jwarp.2017.912096

    Abstract: The monitoring of water bodies means the attempt of protecting vulnerable groups of organisms inhabiting streams and rivers. Industrial and domestic discharges may worsen the water quality and affect biological balance, structure and the functioning of the ecosystem. Cubatão City, is one of the largest industrial centers in Brazil and in Latin America, where the constant discharge of effluents into Cubatão River and its tributaries caused a degradation scenario in the hydrographic basin of the region. The objective of this study was to evaluate the acute and chronic effects of surface water from Cubatão River and two of its tributaries (Perequê and Pilões) by ecotoxicological assays. In addition, physical chemical parameters were analyzed. Ceriodaphnia dubia and Vibrio fischeri were exposed-organisms during the studied period. The study was conducted between 2010 and 2011 in four campaigns and nine sites along the basin of Cubatão River. The ecotoxicity was measured by Vibrio fischeri bioluminescence, EC50 values ranging from 31.25% to 71.61%. In contrast, based on a bioequivalence t-test statistical analysis, the results obtained with Ceriodaphnia dubia revealed no toxicity in the sampling sites. A critical analysis of raw data of luminescence was carried out showing higher values during the 2nd campaign. From the numbers obtained for physical- chemical parameters P5 was far the worst due to chlorides, hardness and conductivity. From the Pearson correlation analysis carried out with toxicity to V. fischeri and the physical chemical parameters, the dissolved oxygen in water resulted in a moderate positive correlation. Sediment contamination was also demonstrated in the region.

    Palavras-Chave: water; water quality; toxicity; surfaces; chronic exposure; chronic exposure; ecosystems; environmental impacts; environment

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  • IPEN-DOC 24374

    ROSTELATO, M.E.C.M. ; SOUZA, D.C.B. ; SOUZA, C.D. ; ZEITUNI, C.A. ; VICENTE, R. ; COSTA, O.L. ; RODRIGUES, B.T. ; MOURA, J.A. ; FEHER, A. ; MOURA, E.S. ; MARQUES, J.R.O. ; CARVALHO, V.S. ; NOGUEIRA, B.R. . Waste management protocols for iridium-192 sources production laboratory used in cancer treatment in Brazil. International Journal of Engineering Research & Science, v. 3, n. 9, p. 45-50, 2017.

    Abstract: Objective: The iridium-192 wired sources production results in radioactive waste that needs to follow the guidelines. The aim of this study is to do a radioactive waste management of wastes from iridium-192 sources production laboratory used in cancer treatment in Brazil. Methods: The wire is acquired in an alloy form with 80% platinum and 20% iridium encapsulated with 100%. Electronic microscopy, X-ray fluorescence, and posterior iridium neutron activation (to determine contaminants) are performed to ensure quality. A 50-cm twisted wire is placed in an aluminum tube. The tube is sealed and place inside the reactor irradiator system and is left for decay during 30 hours to wait for the others undesired activation products to decay. The wire is prepared for treatment with 48 cm length with 192 mCi maximum activity. All the equipment use inside the hot cell must be calibrated every four months. All the waste must be removed from the hot cell. Results: The solid waste is previously characterized in the analysis phase. The contaminants are already known and they are insignificant due to their fast half-life. The iridium-192 half-life is 74.2 days, classified as very short half-life waste. The reminiscent activity is 8mCi. Conclusion: The radioactive waste generated during the I192 wires production is solid, was a short half-life and a weakly activity of 9.7 GBq.g-1. According to the standards, this activity is too high to be discarded into the environment (limit 10 Bq.g-1). The waste must be managed by the R&R (retain e retard) system.

    Palavras-Chave: waste management; radioactive materials; radioactive wastes; neoplasms; therapy; iridium 192; radioactive waste management; sealed sources; brachytherapy

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  • IPEN-DOC 23099

    POLO, IVON O. ; SANTOS, WILLIAM S. ; ANTONIO, PATRICIA de L. ; CALDAS, LINDA V.E. . Variance reduction technique in a beta radiation beam using an extrapolation chamber. Applied Radiation and Isotopes, v. 128, p. 154-157, 2017. DOI: 10.1016/j.apradiso.2017.06.017

    Abstract: This paper aims to show how the variance reduction technique “Geometry splitting/Russian roulette” improves the statistical error and reduces uncertainties in the determination of the absorbed dose rate in tissue using an extrapolation chamber for beta radiation. The results show that the use of this technique can increase the number of events in the chamber cavity leading to a closer approximation of simulation result with the physical problem. There was a good agreement among the experimental measurements, the certificate of manufacture and the simulation results of the absorbed dose rate values and uncertainties. The absorbed dose rate variation coefficient using the variance reduction technique “Geometry splitting/Russian roulette” was 2.85%.

    Palavras-Chave: absorbed radiation doses; dose rates; extrapolation chambers; monte carlo method; radiation sources

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  • IPEN-DOC 23180

    MERGULHAO, MARCELLO V. ; PODESTA, CARLOS E.; NEVES, MAURICIO D.M. das . Valuation of mechanical properties and microstructural characterization of ASTM F75 Co-Cr alloy obtained by Selective Laser Melting (SLM) and casting techniques. Materials Science Forum, v. 899, p. 323-328, 2017. DOI: 10.4028/www.scientific.net/MSF.899.323

    Abstract: Advances in processes using the powder metallurgy techniques are making this technology competitive compared to the other traditional manufacturing processes, especially in medicine area. The additive rapid prototyping technique – selective laser melting (SLM) was applied in a biomaterial of CoCrMoFe alloy (ASTM F75), to study the mechanical properties and microstructural characterization in comparison between the conventional technique – casting. The gas atomized powder was investigated by their physical (as apparent density, bulk density and flow rate) and the chemical properties. The powder was analyzed using scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS) and X-ray fluorescence. Specimens of standard samples were manufactured using these techniques to evaluate the mechanical properties as uniaxial tensile (yield strength, rupture tensile and elongation), transverse rupture strength and the micro hardness. The mechanical properties showed higher values in the SLM specimens than the casting specimens. Before the mechanical tests the specimens were examined using optical microscope (OM) and SEM-EDS. The micrographs revealed a microstructure with finer morphology in the SLM technique and the dendrites in the casting technique.

    Palavras-Chave: microstructure; mechanical properties; biological materials; cobalt alloys; chromium alloys; molybdenum alloys; casting; lasers; melting; powder metallurgy

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  • IPEN-DOC 24336

    CASTRO, LILIANA ; MOREIRA, EDSON G. ; VASCONCELLOS, MARINA B.A. . Use of INAA in the homogeneity evaluation of a bovine kidney candidate reference material. Journal of Radioanalytical and Nuclear Chemistry, v. 311, n. 2, p. 1291-1298, 2017. DOI: 10.1007/s10967-016-4998-8

    Abstract: Instrumental neutron activation analysis was used to evaluate the between bottle homogeneity and the minimum sample intake of a bovine kidney candidate reference material. The mass fractions of ten inorganic constituents were determined, obtaining satisfactory homogeneity results for all of them. Statistical analysis of the results was performed using a one way analysis of variance and multivariate techniques were applied as complementary techniques, confirming the usefulness of these techniques for homogeneity assessment.

    Palavras-Chave: calibration standards; cattle; food processing; inorganic compounds; kidneys; meat; neutron activation analysis; brazil

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  • IPEN-DOC 24333

    BAPTISTA, MAURICIO S.; CADET, JEAN; DI MASCIO, PAOLO; GHOGARE, ASHWINI A.; GREER, ALEXANDER; HAMBLIN, MICHAEL R.; LORENTE, CAROLINA; NUNEZ, SILVIA C.; RIBEIRO, MARTHA S. ; THOMAS, ANDRES H.; VIGNONI, MARIANA; YOSHIMURA, TANIA M. . Type I and type II photosensitized oxidation reactions: guidelines and mechanistic pathways. Photochemistry and Photobiology, v. 93, n. 4, p. 912-919, 2017. DOI: 10.1111/php.12716

    Abstract: Here, 10 guidelines are presented for a standardized definition of type I and type II photosensitized oxidation reactions. Because of varied notions of reactions mediated by photosensitizers, a checklist of recommendations is provided for their definitions. Type I and type II photoreactions are oxygen-dependent and involve unstable species such as the initial formation of radical cation or neutral radicals from the substrates and/or singlet oxygen (O-1(2) (1)Delta(g)) by energy transfer to molecular oxygen. In addition, superoxide anion radical (O-2(.-)) can be generated by a charge-transfer reaction involving O-2 or more likely indirectly as the result of O-2(.)- mediated oxidation of the radical anion of type I photosensitizers. In subsequent reactions, O-2(.-) may add and/or reduce a few highly oxidizing radicals that arise from the deprotonation of the radical cations of key biological targets. O-2(.-) can also undergo dismutation into H2O2, the precursor of the highly reactive hydroxyl radical ((OH)-O-.) that may induce delayed oxidation reactions in cells. In the second part, several examples of type I and type II photosensitized oxidation reactions are provided to illustrate the complexity and the diversity of the degradation pathways of mostly relevant biomolecules upon one-electron oxidation and singlet oxygen reactions.

    Palavras-Chave: oxidation; biological effects; photosensitivity; superoxide radicals; anions

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  • IPEN-DOC 24384

    STEFFENS, DANIELA; MATHOR, MONICA B. ; SOSTER, PAULA R. da L.; VERGANI, GUSTAVO; LUCO, DAYANE P.; PRANKE, PATRICIA. Treatment of a burn animal model with functionalized tridimensional electrospun biomaterials. Journal of Biomaterials Applications, v. 32, n. 5, p. 663-676, 2017. DOI: 10.1177/0885328217735933

    Abstract: Laminin-functionalized poly-D,L-lactic acid scaffolds were produced. Following this, mesenchymal stem cells and keratinocytes were seeded on biomaterials for the in vivo experiments, where the biomaterials with or without cells were implanted. The analysis is comprised of the visual aspect and mean size of the lesion plus the histology and gene expression. The results showed that the cells occupied all the structure of the scaffolds in all the groups. After nine days of in vivo experiments, the defect size did not show statistical difference among the groups, although the groups with the poly-D,L-lactic acid/Lam biomaterial had the lowest lesion size and presented the best visual aspect of the wound. Gene expression analysis showed considerable increase of tumor growth factor beta 1 expression, increased vascular endothelial growth factor and balance of the BAX/Bcl-2 ratio when compared to the lesion group. Histological analysis showed well-formed tissue in the groups where the biomaterials and biomaterials plus cells were used. In some animals, in which biomaterials and cells were used, the epidermis was formed throughout the length of the wound. In conclusion, these biomaterials were found to be capable of providing support for the growth of cells and stimulated the healing of the skin, which was improved by the use of cells.

    Palavras-Chave: burns; biological materials; stem cells; keratin; animal tissues; skin; skin damage; electrodes

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  • IPEN-DOC 23937

    CONCEICAO, LEANDRO da ; LAY, SABINE; ROBAUT, FLORENCE; RENOU, GILLES; MUCCILLO, E.N.S. ; DJURADO, ELISABETH. Transmission electron microscopy characterization of protective La0.7Sr0.3MnO3−delta coatings prepared by electrostatic spray deposition on ferritic alloy. Functional Materials Letters, v. 10, n. 3, p. 1750012-1 - 1750012-5, 2017. DOI: 10.1142/S1793604717500126

    Abstract: The effect of La0:7Sr0:3MnO3 δ (LSM) coating on SS446 steel on air oxidation at 800○C was investigated by transmission electron microscopy. Dense and crack free thin LSM films were prepared by electrostatic spray deposition. The microstructural characterization was carried out on coated and uncoated interconnectors. A thin chromia scale at the alloy interface along with two spinel phases were observed after long term oxidation in both cases. Specimens exhibit, in addition, an SiO2 layer at the interface with steel due to the high content of Si in the steel. Significant changes in the thickness, morphology and composition occurred in the reaction layer for the LSM coated steel. These effects are explained on the basis of changes in the diffusive fluxes during exposure to the oxidation treatment. The implications of these effects for the degradation mechanism of LSM-based interconnects are discussed.

    Palavras-Chave: transmission electron microscopy; lanthanum oxides; solid oxide fuel cells; electrostatics; deposition; interconnected power systems; perovskite

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  • IPEN-DOC 23104

    SILVA, FLAVIA R.O. ; NABESHIMA, CAMILA T.; COURROL, LILIA C.; BELLINI, MARIA H. . Transfer of aminolevulinic acid-induced protoporphyrin IX from tumor cells into the blood. Open Access Journal of Cancer & Oncology, v. 1, n. 1, p. 1-5, 2017.

    Abstract: This work evaluates the δ -aminolevulic acid (ALA)-induced Protoporphyrin IX (PpIX) synthesis and the PPIX transference from the tumor cells to the whole blood cells. Human prostate tumor cells (DU145 cells) received ALA at different periods and doses to analyze the PPIX synthesis. Thereafter, blood of healthy animals was added to the cultured tumorigenic cells to monitor the transference of the PPIX synthesized from them to the blood cells. Our results demonstrated that the intracellular production and accumulation of PPIX into prostate human tumor cells depends on the ALA doses and the time of exposition. Besides, PPIX molecules synthesized by tumor cells were transferred to the blood cells, but they were not transferred to the DMEM medium solution, showing that it is not a simple diffusion process of PPIX migration, but probably a complex efflux mechanism that cells have developed to transport it through the blood cells to regulate PPIX concentration inside them, since an excess of PPIX is highly toxic. These findings can be useful to understand the accumulation of PPIX to the blood of tumor-bearing animals and cancer patients, and it can be useful to design treatment and diagnosis protocols.

    Palavras-Chave: aminolevulinic acid; protoporphyrins; neoplasms; therapy; tumor cells; blood cells; fluorescence; prostate; diagnosis

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  • IPEN-DOC 22834

    LANGE, CAMILA N. ; FIGUEIREDO, ANA M.G. ; ENZWEILER, JACINTA; CASTRO, LILIANA . Trace elements status in the terrain of an impounded vehicle scrapyard. Journal of Radioanalytical and Nuclear Chemistry, 2017. DOI: 10.1007/s10967-016-5078-9

    Abstract: The impact of a scrapyard of impounded vehicles in Sa˜o Paulo state on topsoil was evaluated for As, Ba, Co, Cr, Cu, Mo, Ni, Pb, V, Zn and rare earth elements (REEs). Mass fractions of all elements, except for Co, Cu, Mo and Zn, were higher than reference values. Hot spots were observed for most elements suggesting vehicular source. The geoaccumulation index showed moderate pollution of As. The enrichment factor pointed to a significant enrichment of As, Mo and Pb. The normalization of REEs to Earth’s crust values indicated a positive anomaly of Ce. The results indicate a potential risk to the soil quality of the scrapyard.

    Palavras-Chave: elements; trace amounts; soils; neutron activation analysis; vehicles; urban areas; contamination; x-ray fluorescence analysis

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  • IPEN-DOC 23031

    BRAGA, E.S.; AZEVEDO, J.S.; OLIVEIRA, A.L.; FAVARO, D.I.T. . Trace elements and nuclear abnormalities in fish species of two Brazilian estuarine regions – an attempt to increase the matrix for environmental monitoring. Journal of Aquaculture & Marine Biology, v. 6, n. 2, p. 1-11, 2017. DOI: 10.15406/jamb.2017.06.00148

    Abstract: Trace elements As, Co, Fe, Hg, Se, Zn and Cr were determined in muscle tissue, gills and liver and nuclear abnormalities in erythrocytes (NAEs) were observed in 7 fish species (Chaetodipterusfaber, Paralanchurusbrasiliensis, Micropogoniasfurnieri, Achiruslineatus, Genyatremusluteus, Menticirrhus Americanos and Micropogoniasfurnieri), from two estuarine regions subject to different levels of anthropogenic impact (preserved and polluted) to provide information on contamination levels. The bioaccumulation in C. faber suggested that it should be proposed as a bioindicator of pollution in estuaries. The hydrological data: temperature, salinity and dissolved oxygen characterized the estuarine waters. A paradoxical result relating to As, Co, Fe and Zn concentrations was that, in general, these were higher in the fish species of the Cananeia estuary (a preserved area), while Hg concentrations and NAEs were higher in the species of the Santos-São Vicente estuary (SSV) (the polluted area). The bioaccumulation in tissue-organs decreased in the following order: liver>gill>muscle, with the exception of Hg that was liver>muscle with no detection in gills. Concerning the genotoxic effects, C. faber showed a more significant NAE, besides clastogenic effects, demonstrated by the greater frequency of micronuclei. Differences found between the fish species could be related to their feeding habits and to salinity. This is a contribution to making fishery efforts more profitable and enhancing the bioindicator bank.

    Palavras-Chave: trace amounts; elements; biological markers; toxicity; coastal regions; ecosystems

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  • IPEN-DOC 23074

    MANTILLA, TAIS F.; SILVA, CAMILA V. da; RAMOS-OLIVEIRA, THAYANNE M.; TURSSI, CECILIA P.; RIBEIRO, MARTHA S. ; FREITAS, PATRICIA M. de. TiF4 gel effects on tubular occlusion of eroded/ abraded human dentin. Microscopy Research and Technique, v. 80, p. 1-7, 2017. DOI: 10.1002/jemt.22915

    Abstract: This in situ study evaluated the tubular occlusion caused by 4% TiF4 gel on the surface of eroded/ abraded dentin. Sixty human dentin samples were eroded in vitro and assigned into six groups (n510) according to the in situ surface treatment and number of cycling days: 4% TiF4 gel applied once (TiF41), twice (TiF42), or three times (TiF43) followed by 2, 4, and 6 days of erosive/abrasive in situ cycling, respectively. Control groups (no treatment) were subjected to 2 (C1), 4 (C2), and 6 (C3) days of erosive/abrasive in situ cycling only. A seventh group (n510) was comprised by in vitro uneroded samples (UN), subjected to 6 days of in situ erosive/abrasive cycling. Each cycling day consisted on six erosive (0.5% citric acid, pH 2.6) and one abrasive events. Environmental scanning electron microscopy micrographs were taken. For all groups, blinded examiners assessed dentin tubules occlusion using visual scores (0—unoccluded, 1—partially occluded by granular deposits, 2—partially occluded by reduction in tubular lumen into diamond shape, 3—completely occluded) on images captured prior and after the in situ phase. Scheirer-Ray-Hare test demonstrated that treatments significantly affected tubule occlusion (p<.001). Dunn’s test showed that tubule occlusion in TiF43 was significantly higher than in C1. Tubule occlusion in remaining groups did not differ from that observed in groups TiF43 and C1. Tubule occlusion was significantly higher after in situ phase. It may be suggested that TiF4, when applied three times, was able to positively change tubule occlusion of dentin samples.

    Palavras-Chave: corrosion denting; titanium; titanium fluorides; surfaces; morphology; scanning electron microscopy; environment

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  • IPEN-DOC 23970

    ARAUJO, JULIANO A.; SOUZA, ROBERTO M.; LIMA, NELSON B. de ; TSCHIPTSCHIN, ANDRE P.. Thick CrN/NbN multilayer coating deposited by cathodic arc technique. Materials Research, v. 20, n. 1, p. 200-209, 2017. DOI: 10.1590/1980-5373-MR-2016-0293

    Abstract: The production of tribological nanoscale multilayer CrN/NbN coatings up to 6 μm thick by Sputtering/HIPIMS has been reported in literature. However, high demanding applications, such as internal combustion engine parts, need thicker coatings (>30 μm). The production of such parts by sputtering would be economically restrictive due to low deposition rates. In this work, nanoscale multilayer CrN/NbN coatings were produced in a high-deposition rate, industrial-size, Cathodic Arc Physical Vapor Deposition (ARC-PVD) chamber, containing three cathodes in alternate positions (Cr/ Nb/Cr). Four 30 μm thick NbN/CrN multilayer coatings with different periodicities (20, 10, 7.5 and 4 nm) were produced. The coatings were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The multilayer coating system was composed of alternate cubic rocksalt CrN and NbN layers, coherently strained due to lattice mismatch. The film grew with columnar morphology through the entire stratified structure. The periodicities adopted were maintained throughout the entire coating. The 20 nm periodicity coating showed separate NbN and CrN peaks in the XRD patterns, while for the lower periodicity (≤10nm) coatings, just one intermediate lattice (d-spacing) was detected. An almost linear increase of hardness with decreasing bilayer period indicates that interfacial effects can dominate the hardening mechanisms.

    Palavras-Chave: chromium nitrides; coatings; nanostructures; niobium nitrides; physical vapor deposition; sputtering; transmission electron microscopy; x-ray diffraction

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  • IPEN-DOC 23824

    HEILMAN, SONIA ; MATOS, JIVALDO do R.; ANDRADE e SILVA, LEONARDO G. de . Thermoanalytical study of polyurethane, subjected to ionizing radiation, as raw material for catheters for clinical practice. Journal of Thermal Analysis and Calorimetry, v. 127, n. 3, p. 2353-2358, 2017. DOI: 10.1007/s10973-016-5822-y

    Abstract: The present work aimed to study the thermal behavior of commercial polyurethane catheters before and after irradiation, in order to characterize the polymeric material of these catheters. Fourier transform infrared spectroscopy (FTIR) enabled the identification of functional groups in the structure of macromolecules, such as poly(esterurethane) and poly(etherurethane) in catheters of various origins, and it was confirmed that is a poly (etherurethane) sample. DSC and TG were employed to observe the changes in the properties of the material before and after degradation. DSC curve at the constant heating and cooling rate allowed the characterization of thermal properties, such as Tm and Tg of copolymers, as well as highlighting the main thermal events. TG provided Tonset and Tpeak DTG, where it was possible to evaluate the thermal degradation and the mass loss of the polymer, resulting from a physical transformation such as evaporation or chemical as degradation, in a continuous process as a function of temperature. The comparative assessment conducted between the catheters before and after irradiation by FTIR, Raman and DSC enabled the use of radiation as agent of sterilization.

    Palavras-Chave: ionizing radiations; polyurethanes; thermal analysis; fourier transformation; infrared spectra; spectroscopy

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  • IPEN-DOC 24262

    MELLO, ROBERTA M. de ; BRESSIANI, ANA H. de A. . Thermal Shock Resistance of Liquid Phase Sintered SiC. Materials Science Forum, v. 881, p. 103-108, 2017. DOI: 10.4028/www.scientific.net/MSF.881.103

    Abstract: The aim of this study was to evaluate the effect of Y2O3:Al2O3 additives and sintering temperature on thermal shock resistance of silicon carbide sintered via liquid phase. Silicon carbide samples containing 10 mol% Y2O3:Al2O3 (1:3 and 1:4) were prepared, compacted and sintered at 1750, 1850 and 1950 °C in a graphite resistive furnace. Thermal shock resistance was evaluated after each thermal cycle performed at 600, 750 and 900 °C followed by abrupt cooling in water. Samples with two Y2O3:Al2O3 proportions did not show major differences when sintered at the same temperature, though, rising the sintering temperature improves Y2O3:Al2O3 modified-SiC thermal shock resistance.

    Palavras-Chave: ceramics; dilatometry; fractures; hardness; hot pressing; mechanical properties; microstructure; scanning electron microscopy; silicon carbides; sintering; thermal shock; x-ray diffraction

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  • IPEN-DOC 23228

    FERNANDEZ, ANTONIO P.R. ; GALEGO, EGUIBERTO ; FARIA, RUBENS N. . Thermal Influence on the electric parameters and microstructures of activated powder double layer supercapacitors. Materials Science Forum, v. 899, p. 260-265, 2017. DOI: 10.4028/www.scientific.net/MSF.899.260

    Abstract: The effect of the working temperature on the capacity, internal equivalent serial resistance (ESR), equivalent parallel resistances (EPR) of some retail available electric double layer capacitors (EDLC) have been investigated. Standard capacities of 1.0 F at a maximum potential of 5.5 V were employed in this study. EPR values have been calculated using the self-discharge curves at temperatures above to the nominal maximum working temperature of the supercapacitors (~70oC). The ESR values were measured during charge using the constant current (1 mAF-1) interrupt method with oscilloscope. Microstructural characterization of the electrode material have been carried out using scanning electron microscopy (SEM) and chemical microanalyses employing energy dispersive X-ray analysis (EDX).

    Palavras-Chave: microstructure; capacitive energy storage equipment; energy storage; scanning electron microscopy; powders; fluorescence

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  • IPEN-DOC 23033

    CAMPOS, L.M.P. ; ZAHARESCU, T.; BOARO, L.C.; SANTOS, L.K.G. ; SANTOS, T.M.R. ; FERREIRA, H.P. ; PARRA, D.F. . Thermal and mechanical behavior evaluation of dental composites filled with irradiated montmorillonite. Journal of Applied Polymer Science, v. 134, n. 29, p. 45063-1 - 45063-6, 2017. DOI: 10.1002/app.45063

    Abstract: The effects of pre-irradiation treatment (dose ranged from 25 to 50 kGy) of MMT (Montmorillonite) nanoclay added as filler (50 wt %) in experimental dental composites was studied; composites containing similar amounts of non-irradiated MMT were also tested. The thermal stability of the resulting material was tested by thermogravimetric analysis ranging from 50 to 800 8C. Elastic modulus and flexural strength were determined by the three point bending test (n510). Data for elastic modulus was analyzed using two way ANOVA/Tukey’s test. Data for flexural strength was analyzed using Kruskal–Wallis/Tukey’s test. For all tests, the global significance level was 5%. The modifications in elastic modulus and flexural strength with applied dose were characterized. X-ray diffraction analysis allows the depicting of intercalation phenomenon between base-polymer and nanophase. The polymeric system modified with MMT nanoparticles showed higher thermal stability by delaying the thermal degradation, compared to the control group, and the radiation dose influenced this thermal behavior directly. However, the applied dose was not sufficient to improve the mechanical properties significantly, which is related to the interaction between MMT and polymeric matrix. The pre-irradiation treatment of MMT nanoclay phase was useful for attaining efficient interaction between the two constitutive phases of the polymeric systems based bis-GMA/TEGDMA [bisphenol A bis(2-hydroxy-3-methacryloxypropyl)ether/triethyleneglycol dimethacrylate], modified with MMT nanoparticles, because the polymer component was not affected.

    Palavras-Chave: composite materials; dentin; biological materials; diagnostic techniques; mechanical properties; nanostructures; polymers; thermal gravimetric analysis; x-ray diffraction

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  • IPEN-DOC 23090

    MUCCILLO, R. ; MUCCILLO, E.N.S. ; ANDRADE, T.F. ; OLIVEIRA, O.R. . Thermal analyses of yttrium-doped barium zirconate with phosphor pentoxide, boron oxide and zinc oxide addition. Journal of Thermal Analysis and Calorimetry, 2017. DOI: 10.1007/s10973-017-6523-x

    Abstract: Yttrium-doped barium zirconate (BZY), one of the protonic conductors considered to be used as solid electrolyte in solid oxide fuel cells (SOFC) operating at temperatures lower than the one found in conventional oxide-ion SOFCs, still presents some challenges to reach high density and high electrical conductivity: the difficulty to sinter at temperatures well below its melting point and the blocking of the conducting species at the grain boundaries. We describe an experimental sequence to prepare powders and to obtain highly dense BZY ceramic pellets with enhanced electrical conductivity, using either phosphor pentoxide (P2O5), boron oxide (B2O3) or zinc oxide (ZnO) as sintering aid. The reactions leading to sintering ceramic pellets with densities higher than 94% of the theoretical density and improved electrical performance are monitored by thermal analyses. BZY with the addition of 5 mass% P2O5 or 2 mass% ZnO shows a tenfold enhancement of the electrical conductivity.

    Palavras-Chave: doped materials; electric conductivity; melting points; dilatometry; boron oxides; ceramics; grain boundaries; gravimetry; phosphors; phosphorus oxides; solid electrolytes; solid oxide fuel cells; yttrium additions; zinc oxides; zirconates

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