INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES
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Navegação por Agências de fomento "Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)"

Navegação por Agências de fomento "Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)"

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  • IPEN-DOC 24839

    OSHIRO, MAURICIO T. ; SAKATA, SOLANGE K. ; POTIENS JUNIOR, ADEMAR J. . Adsorption isotherms for the removal of Am-241 in radioactive liquid wastes using magnetite nanoparticles. In: PAN AMERICAN CONGRESS OF NANOTECHNOLOGY, 1st, 27-30 de novembro, 2017, Guarujá, SP. Abstract... 2017.

    Abstract: Americium-241 (Am-241) is a radionuclide with half-life of 432 years, emitting alpha particles and low gamma energy and it is also considered radiotoxic. Am-241 is produced, in a low level, from nuclear fuel and laboratory wastes. Magnetite nanoparticles (Fe3O4) are iron oxides that possess highly magnetic properties, and its application for removal of water contaminants refers due to its high surface area which allows the adsorption capability and the facility to be prepared and removed from the aqueous medium. In This study, magnetite was synthesized by coprecipitation method largely described. Batch experiments were accomplished at room temperature, at pH 6 and the contacts varying from 2.5, 5, 10, 20, 30, 40, 50, 60 minutes and at 30 minutes for the isotherms experiments. The solid containing magnetite and Am-241 were removed with a magnet and the solution analyzed in a gamma-ray spectrometer (Canberra Model GX2518) which could be quantified. Results show that magnetite possess a capability of removal up to 80% of Am-241 at room temperature, indicating that magnetite nanoparticles are a good sorbent for the removal of radionuclides. Langmuir and Freundlich Isotherms models were investigated and the parameters obtained. Langmuir’s isotherm showed constants of KL (75.7575 L/mg), Q (0.1617 mg/g) and R2 (0.9892) and Freundlich’s isotherm exhibited values of KF (2.6416 [(mg/g).(L/mg)1/n]), 1/n (0.7853 mg/g) and R2 (0.8395), which indicates that the Am- 241 removal from magnetite fits more suitable the Langmuir isotherm model. The thermodynamics parameters, such as the enthalpy and entropy of adsorption, the activation energy, as well as, the kinetics studies are under development.

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  • IPEN-DOC 24415

    SANTOS, SILAS C. ; RODRIGUES, ORLANDO ; CAMPOS, LETICIA L. . Advances in colloidal processing of rare earth particles. Current Smart Materials, v. 3, p. 1-18, 2018. DOI: 10.2174/2405465802666171012143956

    Abstract: Abstract: Background: New insights into materials science provide development of smart nano/micro structured materials for advanced applications. Rare earth includes a set of chemical elements (from La to Lu, including Sc and Y) with unique properties, the use of which is evidenced by luminescence applications. Colloidal processing offers great possibilities to obtain smart materials by controlling inter-particle forces, as well as their evolution during ceramic processing. The present article reports a review on colloidal processing with emphasis on rare earth powders. A general view about rare earths properties, including scientific investigations and applications are also presented. Methods: General view on rare earth sources, classification, properties, studies, and applications are reported. Besides, a review on colloidal processing covering particle characteristics, inter- particle forces, dispersion methods, rheology of suspensions, shaping process, drying-sintering stage, and microstructure formation is reported. Results: Yttria is the most used rare earth oxide in phosphors applications (70%). Synthesis routes imply on powder properties. Particle characteristics as size, shape, density, and surface area are important parameters for colloidal processing. The control of inter- particle forces by zeta potential evaluation and using dispersion methods provide conditions to prepare stable suspensions. Consolidation of colloidal particles into a desired shape depends on both viscosity and rheological behavior of suspensions. Drying-sintering conditions are effective on microstructure formation and component characteristics. Bio-prototyping is a low cost method, which provides components with complex shape and cellular architecture. Conclusion: Rare earths exhibit remarkable properties, being applied in diverse technological end-use. Colloidal processing provides opportunities to form smart materials since synthesis of colloids until development of complex ceramic components by shaping methods and thermal treatment. Even though colloidal processing is quite mature, investigations on rare earths involving inter- particle forces, shaping, drying-sintering stage, and microstructure formation are very scarce.

    Palavras-Chave: rare earths; processing; dispersions; particles; rheology; sintering; colloids

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  • IPEN-DOC 26077

    ANA, PATRICIA A.; PEREIRA, DAISA de L. ; FERREIRA, ELIZABETE dos S.; FIGUEREDO, DANIELA C.; DAGUANO, JULIANA K.F.B.; ZEZELL, DENISE M. . Advances in the prevention and monitoring of root dentin demineralization using lasers. In: SBFOTON INTERNATIONAL OPTICS AND PHOTONICS CONFERENCE, October 7-9, 2019, São Paulo, SP. Proceedings... 2019.

    Abstract: The increase in the life expectancy and the longer permanence of the teeth in the oral cavity also led to an augment in the prevalence of root caries lesions. These lesions require more attention because of their rapid progression and difficulty in early diagnosis and monitoring. In this context, the irradiation of the tissues with high intensity lasers has been shown as an important way for preventing lesion formation because lasers chemically modify the irradiated dental hard tissues and make them more resistant to acid challenge. In addition, the association with ceramic biomaterials may allow additional remineralizing results. Together with therapeutics, the effective early diagnosis of incipient lesions is indispensable. Techniques that use lasers, such as optical coherence tomography, have also been promising in this aspect because they allow the early diagnosis and monitoring of demineralizations with high resolution and in a non-detrimental way. This article aims to show the actions of high intensity laser therapies when associated or not with biomaterials, on the prevention and remineralization of root caries lesions, as well as the effectiveness of optical coherence tomography in the diagnosis and monitoring the effects of the treatments in these lesions.

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  • IPEN-DOC 26975

    SANTIAGO, ELISABETE I. ; MATOS, BRUNO R. ; DRESCH, MAURO A.; ISIDORO, ROBERTA A. ; FONSECA, FABIO C. . Advances on Nafion-based composites for high temperature proton exchange membrane fuel cells. In: BRAZIL MRS MEETING, 16th, September 10-14, 2017, Gramado, RS. Abstract... São Carlos, SP: Aptor Software, 2017. p. 55-55.

    Abstract: PEMFC (Proton exchange membrane fuel cell) is considered a promising and efficient hydrogen fuelled electrical power source. However, PEMFC faces several technical problems, such as sluggish electrode reaction kinetics involving the limiting rate of the oxygen reduction and alcohol oxidation reactions, and high resistance to ion transport that could be surpassed with increasing of the operation temperature. The main impediment for such a temperature increase is the water dependent performance of the state-of-the-art Nafion electrolyte. Above 80 ºC water starts to evaporate considerably and Nafion microdomains begin to shrink, disrupting its percolative structure, leading from a conductor to insulator transition. In this work, the incorporation in-situ or ex-situ of an inorganic phase with hydrophilic properties, such as TiO2 and SiO2, into Nafion membranes has been evaluated as an interesting alternative to produce stable electrolytes able to operate at higher temperatures (130o C). The physical-chemistry and electrochemical characterisation has shown that the inorganic particles located in both the nonionic and ionic regions of the ionomer have important contributions to enhanced thermal stability and water uptake. Such features resulted in significant improvements of the PEMFCs using composite electrolytes tested at high operating temperature and low relative humidity. In addition, remarkable enhancement on the DEFC (Direct Ethanol Fuel Cell) performance (122 mW cm‑2) has been obtained as a result of an increase of ethanol oxidation reaction rate promoted by the combination of enhanced catalyst activity and high temperature of operation using stable composite Nafion-SiO2 electrolytes.

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  • IPEN-DOC 27790

    DRESCH, MAURO A. ; MATOS, BRUNO R. ; GODOI, DENIS R.M.; LINARDI, MARCELO ; FONSECA, FABIO C. ; VILLULLAS, HEBE de las M.; SANTIAGO, ELISABETE I. . Advancing direct ethanol fuel cell operation at intermediate temperature by combining Nafion-hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. International Journal of Hydrogen Energy, v. 46, n. 24, p. 13252-13264, 2021. DOI: 10.1016/j.ijhydene.2021.01.123

    Abstract: The advancement of direct ethanol fuel cell (DEFC) represents a real challenge to electrochemical science because ethanol changes significantly the triple phase boundary properties such as the redox reactions and the proton transport. Ethanol molecules promote poor fuel cell performance due to their slow oxidation rate, reduction of the proton transport due to high affinity of ethanol by the membrane, and due to mixed potential when the ethanol molecules reach the cathode by crossover. DEFC performance has been improved by advances in the membranes, e.g., low ethanol crossover polymer composites, or electrode materials, e.g., binary/ternary catalysts. Herein, high temperature (130 °C) DEFC tests were systematically investigated by using optimized electrode and electrolyte materials: Nafion-SiO2 hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. By optimizing both the electrode and the electrolyte in conjunction, DEFCs operating at 130 °C exhibited a threefold increase on performance as compared to standard commercially available materials.

    Palavras-Chave: direct ethanol fuel cells; electrocatalysts; hybridization; electrolytes; nanocomposites

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  • IPEN-DOC 30043

    BAFFA, MATHEUS de F.O.; BACHMANN, LUCIANO; ZEZELL, DENISE M. ; PEREIRA, THIAGO M.; DESERNO, THOMAS M.; FELIPE, JOAQUIM C.. Advancing thyroid pathologies detection with recurrent neural networks and micro-FTIR hyperspectral imaging. In: ALMEIDA, JOAO R. (Ed.); SPILIOPOULOU, MYRA (Ed.); ANDRADES, JOSE A.B. (Ed.); PLACIDI, GIUSEPPE (Ed.); GONZALEZ, ALEJANDRO R. (Ed.); SICILIA, ROSA (Ed.); KANE, BRIDGET (Ed.) INTERNATIONAL SYMPOSIUM ON COMPUTER-BASED MEDICAL SYSTEMS, 36th, June 22-24, 2023, L’Aquila, Italy. Proceedings... Piscataway, NJ, USA: IEEE, 2023. p. 611-615. DOI: 10.1109/CBMS58004.2023.00288

    Abstract: Thyroid disorders are a complex group of diseases that require an accurate diagnosis for effective treatment. Fine-needle aspiration biopsies can assist in detecting many thyroid diseases. These materials can be analyzed visually using traditional computer vision methods, despite the limitations of complex samples. To address this problem, we propose a novel approach that uses hyperspectral imaging (HSI) to analyze thyroid biological samples. HSI measures the absorbance of infrared light by biological samples using a micro Fourier transform infrared spectroscopy (micro-FTIR) and converts this data into hyperspectral images. In this study, we used HSI to train and validate a recurrent neural network to classify thyroid samples as healthy, cancerous, or goiter. Our experiments, based on the k-fold cross-validation, achieved an overall accuracy of 96.88%, a sensitivity of 96.87%, and a specificity of 98.45%. These results demonstrate the potential of hyperspectral imaging as a tool to assist pathologists in the diagnosis of thyroid disease.

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  • IPEN-DOC 28093

    YOSHIDA, A.C. ; LOPES, F.J.S. ; CACHEFFO, A. ; MOREIRA, G.A. ; SILVA, J.J. da ; LANDULFO, E. . AEOLUS calibration and validation activities at SPU Lidar Station - Brazil. In: EUROPEAN LIDAR CONFERENCE, November 18-20, 2020, Granada, Spain. Resumo expandido... 2020. p. 1-2.

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  • IPEN-DOC 29590

    RAMOS, LUIZ D.; MANTOVANI, MARIANA C. ; SARTORI, ADRIANO; DUTRA, FERNANDO; STEVANI, CASSIUS V.; BECHARA, ETELVINO J.H. Aerobic co-oxidation of hemoglobin and aminoacetone. In: SILVA, FERNANDO de C. da (Org.) REUNIAO ANUAL DA SBQ, 45., 31 de maio - 3 de junho, 2022, Maceió, AL. Resumo... São Carlos, SP: Aptor Software, 2022. p. 164-164.

    Abstract: Aminoacetone (1-aminopropan-2-one), a putative minor biological source of methylglyoxal, reacts like other 􀄮-aminoketones such as 6-aminolevulinic acid (first heme precursor) yielding electrophilic 􀄮-oxoaldehydes, ammonium ion and reactive oxygen species by metal- and hemeprotein catalyzed aerobic oxidation 1,2. A wealth of reports implicates methylglyoxal in protein crosslinking and DNA addition, leading to age-related disorders, including diabetes 3,4. Importantly, methylglyoxal-treated hemoglobin adds four water-exposed arginine residues, which may compromise its physiological role and potentially serve as biomarkers for diabetes 5. In this work, we investigate the co-oxidation of aminoacetone and oxyhemoglobin in normally aerated phosphate buffer, leading to structural changes in hemoglobin, which might reportedly be attributed to the addition of aminoacetone-generated methylglyoxal to the protein. Hydroxyl radical-promoted chemical damage to hemoglobin may also occur in parallel, which is suggested by EPR-spin trapping studies with 5,5-dimethyl-1-pyrroline-N-oxide and ethanol. Concomitantly, oxyhemoglobin is oxidized to methemoglobin, as indicated by characteristic CD spectral changes in the absorption Soret and visible regions. Overall, these findings may contribute to elucidate the molecular mechanisms underlying human diseases associated with hemoglobin dysfunctions (e.g., diabetes) and with aminoacetone in metabolic alterations related to excess of glycine and threonine (e.g., threoninemia, cri-du-chat syndrome).

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  • IPEN-DOC 27786

    RAMOS, LUIZ D.; MANTOVANI, MARIANA C. ; SARTORI, ADRIANO; DUTRA, FERNANDO; STEVANI, CASSIUS V.; BECHARA, ETELVINO J.H.. Aerobic co-oxidation of hemoglobin and aminoacetone, a putative source of methylglyoxal. Free Radical Biology and Medicine, v. 166, p. 178-186, 2021. DOI: 10.1016/j.freeradbiomed.2021.02.023

    Abstract: Aminoacetone (1-aminopropan-2-one), a putative minor biological source of methylglyoxal, reacts like other α-aminoketones such as 6-aminolevulinic acid (first heme precursor) and 1,4-diaminobutanone (a microbicide) yielding electrophilic α-oxoaldehydes, ammonium ion and reactive oxygen species by metal- and hemeprotein-catalyzed aerobic oxidation. A plethora of recent reports implicates triose phosphate-generated methylglyoxal in protein crosslinking and DNA addition, leading to age-related disorders, including diabetes. Importantly, methylglyoxal-treated hemoglobin adds four water-exposed arginine residues, which may compromise its physiological role and potentially serve as biomarkers for diabetes. This paper reports on the co-oxidation of aminoacetone and oxyhemoglobin in normally aerated phosphate buffer, leading to structural changes in hemoglobin, which can be attributed to the addition of aminoacetone-produced methylglyoxal to the protein. Hydroxyl radical-promoted chemical damage to hemoglobin may also occur in parallel, which is suggested by EPR-spin trapping studies with 5,5-dimethyl-1-pyrroline-N-oxide and ethanol. Concomitantly, oxyhemoglobin is oxidized to methemoglobin, as indicated by characteristic CD spectral changes in the Soret and visible regions. Overall, these findings may contribute to elucidate the molecular mechanisms underlying human diseases associated with hemoglobin dysfunctions and with aminoacetone in metabolic alterations related to excess glycine and threonine.

    Palavras-Chave: hemoglobin; electron transfer; amino acids; acetone; glyoxal; peroxy radicals

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  • IPEN-DOC 27164

    BENALCAZAR JALKH, E.B.; BERGAMO, E.T.P.; MONTEIRO, K.N.; CESAR, P.F.; GENOVA, L.A. ; LOPES, A.C.O.; LISBOA FILHO, P.N.; COELHO, P.G.; SANTOS, C.F.; BORTOLIN, F.; PIZA, M.M.T.; BONFANTE, E.A.. Aging resistance of an experimental zirconia-toughened alumina composite for large span dental prostheses: optical and mechanical characterization. Journal of the Mechanical Behavior of Biomedical Materials, v. 104, p. 1-9, 2020. DOI: 10.1016/j.jmbbm.2020.103659

    Abstract: Purpose: To synthesize a zirconia-toughened alumina (ZTA) composite with 85% alumina matrix reinforced by 15% zirconia and to characterize its optical and mechanical properties before and after artificial aging, to be compared with a conventional dental zirconia (3Y-TZP). Material and methods: After syntheses, ZTA and 3Y-TZP powders were uniaxially and isostatically pressed. Greenbody samples were sintered and polished to obtain 80 disc-shaped specimens per group (12 x 1 mm, ISO 6872:2015). The crystalline content and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties were determined by the calculation of contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength test (BFS). All analyses were conducted before and after artificial aging (20h, 134 °C, 0.22 MPa). Optical parameters and microhardness differences were evaluated through repeated-measures analysis of variance (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). Results: The synthesis of the experimental ZTA composite was successful, with 98% of theoretical density, as shown in the SEM images. XRD patterns revealed typical zirconia and alumina crystalline phases. ZTA optical properties parameters showed no effect of aging, with a high CR and low TP values denoting a high maskingability. 3Y-TZP presented lower masking-ability and aging significantly affected its optical properties. ZTA Vickers hardness, fracture toughness and Weibull parameters, including characteristic stress and Weibull modulus were not influenced by aging, while 3Y-TZP presented a significant decrease in characteristic stress and increase in fracture toughness after aging. The ZTA probability of survival for missions of 300 and 500 MPa was estimated at ~99% validating its use for 3-unit posterior fixed dental prostheses (FDP), and no different from conventional 3Y-TZP. At high-stress mission (800 MPa) a significant decrease in probability of survival was observed for aged 3Y-TZP (84%) and for immediate and aged ZTA (73 and 82% respectively). Conclusion: The ZTA composite presented a dense microstructure, with preservation of the crystalline content, optical and mechanical properties after artificial aging, which encourages future research to validate its potential use for large span FDP.

    Palavras-Chave: aluminium oxides; zirconium oxides; aging; ceramics; microstructure; optical properties; optical microscopes

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  • IPEN-DOC 27560

    JALKH, ERNESTO B.B.; MONTEIRO, KELLI N.; CESAR, PAULO F.; GENOVA, LUIS A. ; BERGAMO, EDMARA T.P.; LOPES, ADOLFO C. de O.; LIMA, ERICK; LISBOA-FILHO, PAULO N.; CAMPOS, TIAGO M.B.; WITEK, LUKASZ; COELHO, PAULO G.; BORGES, ANA F.S.; BONFANTE, ESTEVAM A.. Aging resistant ZTA composite for dental applications: microstructural, optical and mechanical characterization. Dental Materials, v. 36, n. 9, p. 1190-1200, 2020. DOI: 10.1016/j.dental.2020.05.011

    Abstract: Objective. To synthesize a zirconia toughened alumina (ZTA) composite with 70% aluminareinforced by 30% zirconia for dental applications and to characterize its microstructureand optical properties for comparison with the isolated counterpart materials and a first-generation 3Y-TZP.Methods. Disc-shaped specimens were divided in four groups (n = 70/material): (1) 3YSB-E(first generation 3Y-TZP), (2) Zpex (second generation 3Y-TZP), (3) alumina, and (4) ZTA-Zpex70/30. After synthesis, ceramic powders were pressed, and green-body samples sinteredfollowing a predetermined protocol. Specimens were polished to obtain a mirror surfacefinish. Apparent density was measured by Archimedes principle. X-ray diffraction (XRD)and scanning electron microscope (SEM) were used to characterize the crystalline contentand microstructure. Reflectance tests were performed to determine the contrast-ratio (CR)and translucency-parameter (TP). Mechanical properties were assessed by biaxial flexuralstrength (BFS) test. All analyses were conducted before and after artificial aging (20 h, 134◦C, 2.2 bar). Optical parameters were evaluated through repeated-measures analysis of variance and Tukey tests (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). Results. High density values (95–99%) were found for all ceramic materials and SEM images exhibited a dense microstructure. While XRD patterns revealed the preservation of crys- talline content in the ZTA composite, an increase in the monoclinic peak was observed for pure zirconias after aging. Significantly higher CR and lower TP values were observed for the ZTA composite, followed by alumina, 3YSB-E, and Zpex. The highest characteristic stress was recorded for 3YSB-E, followed by intermediate values between ZTA and Zpex, and the lowest for alumina. Aging affected the optical and mechanical properties of both zirconias, while remained stable for ZTA composite and alumina. Significance. The synthesis of experimental 70−30% ZTA composite was successful and its relevance for dental applications relies on its higher masking ability, aging resistance, and strength similar to zirconia.

    Palavras-Chave: composite materials; zirconium oxides; aluminium oxides; mechanical properties; optical properties; microstructure; dentistry; prostheses

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  • IPEN-DOC 29608

    GENESI, BIANCA P.; BARBOSA, RAQUEL de M.; SEVERINO, PATRICIA; RODAS, ANDREA C.D.; YOSHIDA, CRISTIANA M.P.; MATHOR, MONICA B. ; LOPES, PATRICIA S.; VISERAS, CESAR; SOUTO, ELIANA B.; SILVA, CLASSIUS F. da. Aloe vera and copaiba oleoresin-loaded chitosan films for wound dressings: microbial permeation, cytotoxicity, and in vivo proof of concept. International Journal of Pharmaceutics, v. 634, p. 1-12, 2023. DOI: 10.1016/j.ijpharm.2023.122648

    Abstract: Chitosan films are commonly used for wound dressing, provided that this polymer has healing, mucoadhesiveness and antimicrobial properties. These properties can be further reinforced by the combination of chitosan with polysaccharides and glycoproteins present in aloe vera, together with copaiba oleoresin’s pharmacological activity attributed to sesquiterpenes. In this work, we developed chitosan films containing either aloe vera, copaiba oil or both, by casting technique, and evaluated their microbial permeation, antimicrobial activity, cytotoxicity, and in vivo healing potential in female adult rats. None of the developed chitosan films promoted microbial permeation, while the cytotoxicity in Balb/c 3 T3 clone A31 cell line revealed no toxicity of films produced with 2 % of chitosan and up to 1 % of aloe vera and copaiba oleoresin. Films obtained with either 0.5 % chitosan or 0.5 % copaiba oleoresin induced cell proliferation which anticipate their potential for closure of wound and for the healing process. The in vivo results confirmed that tested films (0.5 % copaiba-loaded chitosan film and 0.5 % aloe vera-loaded chitosan film) were superior to a commercial dressing film. For all tested groups, a fully formed epithelium was seen, while neoformation of vessels seemed to be greater in formulations-treated groups than those treated with the control. Our work confirms the added value of combining chitosan with aloe vera and copaiba oil in the healing process of wounds.

    Palavras-Chave: medicinal plants; trees; polysaccharides; glycoproteins; wounds; healing

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  • IPEN-DOC 27575

    LICHTENTHALER, R.; APPANNABABU, S.; ALVAREZ, M.A.G.; RODRIGUEZ-GALLARDO, M.; LEPINE-SZILY, A.; PIRES, K.C.C.; SANTOS, O.C.B.; UMBELINO, U.; FARIA, P.N. de; GUIMARAES, V.; ZEVALLOS, E.O.N.; SCARDUELLI, V.; ASSUNCAO, M.; SHORTO, J.M.B. ; BARIONI, A.; ALCANTARA-NUNEZ, J.; MORCELLE, V.; SERRA, A.. Alpha-particle production in the 6He+120Sn collision. Journal of Physics: Conference Series, v. 1643, p. 1-6, 2020. DOI: 10.1088/1742-6596/1643/1/012093

    Abstract: Alpha particle energy distributions in the 6He+120Sn collision have been measured at 7 bombarding energies above the Coulomb barrier. A phenomenological analysis of the centroids of the experimental distributions was performed and compared with the expected alpha-particle energies from breakup and neutron transfer reactions. Q-optimum conditions were determined using the Brinks formula for the di-neutron transfer reaction. A comparison of the measured alpha-particle production cross-sections with Continuum Discretized Coupled Channels (CDCC) calculations for breakup is presented.

    Palavras-Chave: alpha particles; helium 6; energy spectra; elastic scattering; neutron transfer; coupled channel theory; angular momentum

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  • IPEN-DOC 09985

    PEREIRA, ANDREA A. . Alteracoes quimicas e fisicas de tecidos duros irradiados por laser de neodimio chaveado. 2003. Tese (Doutoramento) - Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP, Sao Paulo. 127 p. Orientador: Denise Maria Zezell. Coorientador: Wagner de Rossi.

    Palavras-Chave: dentistry; lasers; teeth; enamels; neodymium lasers; biological effects; animal tissues; biological materials; lasers; chemical analysis

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  • IPEN-DOC 23325

    SILVA, LEANDRO G. da ; SAMAD, RICARDO E. ; VIEIRA JUNIOR, NILSON D. ; ROSSI, WAGNER de . Alteração da cor no aço ASTM F138 por meio de irradiação com laser de femtossegundo / Color change in metals by means of regular nanostructures produced by femtosecond laser pulses. In: ABM WEEK; CONGRESSO ANUAL DA ABM, 71.; ENCONTRO NACIONAL DE ESTUDANTES DE ENGENHARIA METALURGICA, DE MATERIAIS E DE MINAS, 16., 26-30 de setembro, 2016, Rio de Janeiro, RJ. Anais... São Paulo: Associação Brasileira de Metalurgia, Materiais e Mineração, 2016. p. 128-134.

    Abstract: Neste trabalho, foram estudados os efeitos da irradiação de uma superfície polida do aço inoxidável tipo ASTM F138 com laser de pulsos ultracurtos. As irradiações foram realizadas variando-se a velocidade de varredura do laser, ou seja, a taxa de sobreposição espacial de pulsos. Foi observado que após a irradiação houve uma visível mudança na coloração da amostra. Também foi verificado que com o aumento da taxa de sobreposição de pulsos a superfície tendeu a tornar-se preta, ou seja, absorvedora de luz. Com essa técnica, pode-se realizar marcações com alto contraste sem que haja formação de camadas de óxidos, nitretos ou alterações microestruturais no metal, o que é importante para um material com a precisão que um implante exige.

    Palavras-Chave: lasers; pulses; color; stainless steels; surfaces; nanostructures

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  • IPEN-DOC 27075

    SANTOS, G.L.; SANTUCCI, G.; OLIVEIRA-SILVA, T.; PRATES, R.A.; RIBEIRO, M.S. ; KATO, I.T.. Alteração da susceptibilidade de C. albicans resistente ao fluconazol após terapia fotodinâmica. In: VIEIRA NETO, HUGO (Ed.); SOARES, ALCIMAR B. (Ed.); FÉLIX, RODRIGO P.B. da C. (Ed.); VIEIRA NETO, HUGO (Org.); MAIA, JOAQUIM M. (Org.); PICHORIM, SÉRGIO F. (Org.); GAMBA, HUMBERTO R. (Org.); COSTA, EDUARDO T. (Org.) CONGRESSO BRASILEIRO DE ENGENHARIA BIOMÉDICA, 25., 17-20 de outubro, 2016, Foz do Iguaçu, PR. Resumo... Rio de Janeiro, RJ: Sociedade Brasileira de Engenharia Biomédica, 2016. p. 2336-2336.

    Abstract: Introdução: As doenças infecciosas causadas por fungos ainda representam um grande desafio para os profissionais de saúde e a comunidade científica, especialmente as infecções causadas por micro-organismos resistentes aos fármacos antifúngicos convencionais. Novas alternativas de tratamento foram estudadas, entre elas a terapia fotodinâmica (PDT) que surgiu como uma promissora modalidade terapêutica por causar a morte de micro-organismos a partir da associação de um fotossensibilizador e luz. Recentemente observamos que a PDT realizada em condições subletais aumenta a suscetibilidade do fungo Candida albicans ao fluconazol [1]. Dando continuidade a este estudo iniciamos a investigação em C. albicans que apresentam diferentes mecanismos de resistência aos antifúngicos. Assim, o presente trabalho teve o objetivo de avaliar o efeito antimicrobiano da associação de PDT e fluconazol em C. albicans que apresenta um sistema de efluxo responsável pela resistência ao antifúngico. Materiais e Métodos: Para a realização deste trabalho foi utilizado C. albicans YEM 13, uma cepa com expressão exacerbada de bomba de efluxo da família MFS (Major Facilitator Superfamily). As células foram submetidas a PDT com azul de metileno na concentração final de 50 μM e irradiadas com parâmetros subletais (=660 nm, 75 mW/cm2, 4 min)[1]. Para investigar a atividade antimicrobiana do fluconazol foram determinados os valores de concentração mínima inibitória (CMI) do crescimento celular. A CMI foi determinada pelo método de microdiluição em caldo de acordo com as normas estabelecidas pelo Comitê Europeu de Teste à Susceptibilidade Antimicrobiana (EUCAST)[2]. A solução de fluconazol (Sigma Aldrich, São Paulo, Brasil) foi preparada, considerando a potência do fármaco de 98% e a faixa de concentrações testadas foi de 0,125-64 μg/mL. Os valores de CMI foram determinados por meio da leitura da absorção em 530 nm, em espectrofotômetro (SpectraMax M4, Molecular Devices, EUA). Para cada grupo foi determinada a menor concentração da droga que promoveu a inibição ≥ 50% do crescimento em comparação ao controle livre de drogas. Foram avaliadas células C. albicans YEM 13 sem tratamento e previamente submetidas a PDT subletal. Foi utilizado como controle a cepa de C. albicans ATCC 90028 que não apresenta resistência ao fluconazol. Resultados: C. albicans ATCC 90028 apresentou valor de CMI de 0,5 μg/mL, dado compatível com os descritos na literatura. As amostras de célula YEM 13 que não foram submetidas à PDT apresentaram o valor de CMI de 64 μg/mL, que também coincide com o valor descrito na literatura [3]. Estes dados demonstram que a cepa YEM 13 apresenta um valor de CMI 128 vezes superior ao de uma cepa suscetível ao fluconazol (ATCC 90028). Confirmando nossa hipótese, o fluconazol foi mais ativo em C. albicans submetida previamente à PDT subletal. Dentro da faixa de 0,125-64 μg/mL, houve maior inibição do crescimento celular quando previamente submetido à PDT, resultando na redução do valor de CMI de 64 μg/mL para 32 μg/mL. Conclusões: Foi possível demonstrar que a PDT pode aumentar a susceptibilidade ao fluconazol em cepa de C. albicans que apresentam bombas de efluxo da família MFS. Estes resultados preliminares sugerem que a associação terapêutica entre a PDT e o fluconazol pode ser uma importante alternativa no tratamento de infecções por cepas de C. albicans que apresentam resistência a este antifúngico. Vale ressaltar que neste trabalho foram utilizadas condições subletais e resultados ainda mais promissores podem ser obtidos com a otimização dos parâmetros de irradiação.

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  • IPEN-DOC 14981

    KATO, I.T.; ZEZELL, D.M. ; MENDES, F.M.; WETTER, N.U. . Alterations in enamel remineralization in vitro induced by blue light. Laser Physics, v. 20, n. 6, p. 1469-1474, 2010.

    Palavras-Chave: enamels; mineralization; light emitting diodes; light sources; laser radiation; biological radiation effects

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  • IPEN-DOC 09618

    ROSAURO, CRISTIANE W. . Altos niveis de expressao de hormonio de crescimento de camundongo em queratinocitos humanos visando a obtencao de um modelo animal de terapia genica. 2003. Dissertacao (Mestrado) - Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP, Sao Paulo. 98 p. Orientador: Cibele Nunes Peroni.

    Palavras-Chave: molecular biology; mice; sth; cell cultures; animal cells; epidermis; genes; in vitro

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  • IPEN-DOC 27841

    BERGAMO, EDMARA T.P.; CARDOSO, KARINA B.; LINO, LUCAS F.O.; CAMPOS, TIAGO M.B.; MONTEIRO, KELLI N.; CESAR, PAULO F.; GENOVA, LUIS A. ; THIM, GILMAR P.; COELHO, PAULO G.; BONFANTE, ESTEVAM A.. Alumina-toughened zirconia for dental applications: physicochemical, mechanical, optical, and residual stress characterization after artificial aging. Journal of Biomedical Materials Research Part B: Applied Biomaterials, v. 109, n. 8, p. 1135-1144, 2021. DOI: 10.1002/jbm.b.34776

    Abstract: To characterize the physicomechanical properties of an alumina-toughened zirconia (ATZ). ATZ synthesis consisted of the addition of alumina particles in an yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) matrix. Specimens were obtained by uniaxial and isostatic pressing ATZ and 3Y-TZP powders and sintering at 1600°C/1 h and 1550°C/1 h, respectively. Crystalline content and residual stress were evaluated using X-ray diffraction (XRD). Microstructure was characterized by scanning electron microscopy (SEM). Optical properties were determined by reflectance test. Mechanical properties were assessed by biaxial flexural strength test. All analyses were performed before and after aging (134°C, 20 h, 2 bar). XRD and SEM revealed a typical ATZ and 3Y-TZP crystalline content, chiefly tetragonal phase, with a dense polycrystalline matrix, though a smaller grain size for ATZ. Aging triggered a similar monoclinic transformation for both systems; however, ATZ exhibited higher residual compressive stresses than 3Y-TZP. While as-processed 3Y-TZP demonstrated significantly higher characteristic strength relative to ATZ, no significant difference was observed after aging (~215 MPa increase in the ATZ strength). ATZ presented significantly higher opacity relative to 3Y-TZP, although aging significantly increased the translucency of both systems (increase difference significantly higher in the 3Y-TZP compared to ATZ). ATZ physicomechanical properties support its applicability in the dental field, with a lower detrimental effect of aging relative to 3Y-TZP.

    Palavras-Chave: zirconium; dentistry; ceramics; composite materials; optical properties; aging

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  • IPEN-DOC 27448

    BASSO, LUANA; GATTI, LUCIANA ; MARANI, LUCIANO; CASSOL, HENRIQUE; TEJADA, GRACIELA; DOMINGUES, LUCAS ; CORREIA, CAIO ; CRISPIM, STEPHANE; NEVES, RAIANE; IPIA, ALBER; ARAI, EGIDIO; ARAGAO, LUIZ; MILLER, JOHN; GLOOR, MANUEL. Amazon CH4 budget and its controls based on atmospheric data from vertical profiles measurements. In: EGU General Assembly, May 4-8, 2020, Online. Abstract... Göttingen, Germany: Copernicus, 2020.

    Abstract: Wetland emissions are considered the main natural global Methane (CH4) source, but it is budget remains highly uncertain. Tropical regions like the Amazon, host some of the largest wetlands/seasonally flooded areas on the globe. However, tropical regions are still poorly observed with large-scale integrating observations. Here we present the first atmospheric sampling of the lower troposphere over the Amazon using regular vertical profile greenhouse gas and carbon monoxide (CO) observations at four sites. Since 2010 we collected bimonthly CH4, to provide solid seasonal and annual CH4 budgets with large spatial resolution. Vertical profiles are sampled using light aircraft, high-precision greenhouse gas and CO analysis of flask air, fortnightly between 2010 to 2018. The results show a regional variation in CH4 emissions. There are comparably high emissions from the northeast part of the Amazon exhibiting strong variability, with particularly high CH4 fluxes in the beginning of the wet season (January to March). A second period of high emissions occurs during the dry season. The cause of the high emissions is unclear. In the other three sites located further downwind along the main air-stream are observed lower emissions, that represents approximately 25-30% of what is observed in the northeast region and with a clear annual seasonality. In addition, these data show an interannual variability in emissions magnitude, so we discuss how these data can be correlate to climate variables (like temperature and precipitation) and with human-driven changes (like biomass burning) that could be influencing this variability. Over the full period the Amazon (total area of around 7.2 million km2) was a source of CH4, of approximately 46 ± 6 Tg/year, which represent 8% of the global CH4 flux to the atmosphere. Using a CO/CH4 emission ratio calculated in this study we find a biomass burning contribution varying between 10 and 23% of the total flux at each site.

    Palavras-Chave: methane; atmospheres; carbon monoxide; greenhouse gases; wetlands

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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.