INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES
Repositório Digital da Produção Técnico Científica

BibliotecaTerezine Arantes Ferraz

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

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

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  • IPEN-DOC 23152

    BERECZKI, ALLAN ; WETTER, NIKLAUS U. . 100W continuous linearly polarized, high beam quality output from standard side-pumped Nd:YAG laser modules. Optics and Laser Technology, v. 96, p. 271-275, 2017. DOI: 10.1016/j.optlastec.2017.05.020

    Abstract: Dynamically stable operation with joined stability zones of a linearly polarized resonator is shown for a laser containing two diode side-pumped Nd:YAG rods. The unpolarized resonator generated 115W of output. When polarized by a Brewster plate, it reached 100.5W of output power at a beam quality M2 < 2. Best measured beam quality was of 1.1 and 1.3 in the x and y directions respectively, with 76W of 95% polarized output. The output power achieved is, to our knowledge, the highest reported for continuous polarized, fundamental-mode lasers using standard side-pumped Nd:YAG modules.

    Palavras-Chave: neodymium lasers; lasers; resonators; solid state lasers; temperature dependence; diode-pumped solid state lasers; beams; quality factor

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  • IPEN-DOC 24704

    ARAGAO, LUIZ E.O.C.; ANDERSON, LIANA O.; FONSECA, MARISA G.; ROSAN, THAIS M.; VEDOVATO, LAURA B.; WAGNER, FABIEN H.; SILVA, CAMILA V.J.; SILVA JUNIOR, CELSO H.L.; ARAI, EGIDIO; AGUIAR, ANA P.; BARLOW, JOS; BERENGUER, ERIKA; DEETER, MERRITT N.; DOMINGUES, LUCAS G. ; GATTI, LUCIANA ; GLOOR, MANUEL; MALHI, YADVINDER; MARENGO, JOSE A.; MILLER, JOHN B.; PHILLIPS, OLIVER L.; SAATCHI, SASSAN. 21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions. Nature Communications, v. 9, n. 536, 2018. DOI: 10.1038/s41467-017-02771-y

    Abstract: Tropical carbon emissions are largely derived from direct forest clearing processes. Yet, emissions from drought-induced forest fires are, usually, not included in national-level carbon emission inventories. Here we examine Brazilian Amazon drought impacts on fire incidence and associated forest fire carbon emissions over the period 2003-2015. We show that despite a 76% decline in deforestation rates over the past 13 years, fire incidence increased by 36% during the 2015 drought compared to the preceding 12 years. The 2015 drought had the largest ever ratio of active fire counts to deforestation, with active fires occurring over an area of 799,293 km(2). Gross emissions from forest fires (989 +/- 504 Tg CO2 year(-1)) alone are more than half as great as those from old-growth forest deforestation during drought years. We conclude that carbon emission inventories intended for accounting and developing policies need to take account of substantial forest fire emissions not associated to the deforestation process.

    Palavras-Chave: carbon dioxide; deforestation; forests; monitoring; greenhouse gases; tropical regions; climates; droughts; fires; amazon river; brazil

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  • IPEN-DOC 19230

    VIANA, R.S.; AGASTHYA, G.A.; YORIYAZ, H. ; KAPADIA, A.J.. 3D element imaging using NSECT for the detection of renal cancer: a simulation study in MCNP. Physics in Medicine and Biology, v. 58, n. 17, p. 5867-5883, 2013.

    Palavras-Chave: kidneys; carcinomas; computerized tomography; three-dimensional calculations; neutron emission; stimulated emission; simulation; m codes

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  • IPEN-DOC 26646

    SILVA, J.P.L. ; TEIXEIRA, L.F. ; BELLINI, M.H. . [6]-Gingerol decreases clonogenicity and radioresistance of human prostate cancer cells. Clinical Oncology and Research, v. 2, n. 5, p. 1-3, 2019. DOI: 10.31487/j.COR.2019.05.07

    Abstract: The phenolic compound [6]-Gingerol, isolated from Zingiber officinale, has been demonstrated to have antitumor activity for different types of malignant tumours. Prostate cancer is the most common malignancy among males worldwide, being the second leading cause of cancer death in men. In the present study, we investigated the antitumor action of [6]-Gingerol on a human prostate cancer cell line (LNCaP). Our data shows that [6]-Gingerol treatment induced a dose-dependent decrease in the cell viability. Compared with the vehicle control, the cell viabilities were 79.90 ± 3.56% and 53.06 ± 7.82% when the LNCaP cells were exposed to 150 μg/mL and 300 μg/mL of [6]-Gingerol, respectively. The treatment of LNCaP with 300 μM of [6]-Gingerol led to a significant reduction (~25%) on the clonogenic survival of these cells. Furthermore, [6]-gingerol acted as a radiosensitizer for LNCaP cells. The pretreatment of these cells with [6]-Gingerol significantly enhanced the killing effects of ionizing radiation with a dose enhancement ratio of 1.25. Our results demonstrate the anti-tumour activities of [6]-Gingerol. Further studies are needed to elucidate the mechanisms involved.

    Palavras-Chave: prostate; neoplasms; radiosensitivity effects; radiosensitizers; radiosensitivity; clone cells; cloning; viability; medicinal plants; spices; radiotherapy; tumor cells

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  • IPEN-DOC 24719

    CARVALHO, SABRINA G.M. ; MUCCILLO, ELIANA N.S. ; MUCCILLO, REGINALDO . AC electric field assisted pressureless sintering zirconia: 3mol% yttria solid electrolyte. Physica Status Solidi A: applications and materials science, v. 215, n. 6, p. 1700647-1 - 1700647-5, 2018. DOI: 10.1002/pssa.201700647

    Abstract: 3mol% yttria ionic conductors are sintered by applying AC electric fields with frequencies in the 0.5-1.0kHz range at 1100 degrees C. The sintering experiments are conducted in pressed pellets positioned between platinum electrodes inside a dilatometer furnace. The dilatometer is modified in order to allow for the simultaneous monitoring of thickness shrinkage, electric voltage, and current across the pellet. The results show that the higher the frequency of the electric field, the higher the attained shrinkage and the apparent density of the pellets. Increasing the frequency of the applied electric field leads to an increase in the Joule heating promoted by the electric current pulse through the polycrystalline ceramic sample. A higher frequency therefore leads to higher amount of thermal energy delivered to the sample, favoring enhanced densification. The ionic resistivity decreases in pellets sintered with increasing frequency of the applied electric field. We suggest that Joule heating favors pore elimination and the removal of chemical species at the space charge region, inhibiting the blocking of oxide ions at the interfaces.

    Palavras-Chave: ac systems; ceramics; dilatometry; electric fields; electric impedance; hz range; ionic conductivity; joule heating; pellets; polycrystals; porosity; shrinkage; sintered materials; sintering; density; solid electrolytes; temperature range 1000-4000 k; thickness; yttrium oxides; zirconium oxides

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  • IPEN-DOC 18371

    AZEVEDO, JULIANA de S.; HORTELLANI, MARCOS A. ; SARKIS, JORGE E.S. . Accumulation and distribution of metals in the tissues of two catfish species from Cananéia and Santos - São Vicente Estuaries. Brazilian Journal of Oceanography, v. 60, n. 4, p. 463-472, 2012.

    Palavras-Chave: brazil; coastal waters; estuaries; contamination; metals; copper; zinc; cadmium; lead; fishes; animal tissues; biological accumulation

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  • IPEN-DOC 26619

    NANDENHA, J. ; NAGAHAMA, I.H.F. ; YAMASHITA, J.Y. ; FONTES, E.H. ; AYOUB, J.M.S. ; SOUZA, R.F.B. de ; FONSECA, F.C. ; NETO, A.O. . Activation of methane on PdZn/C electrocatalysts in an acidic electrolyte at low temperatures. International Journal of Electrochemical Science, v. 14, n. 12, p. 10819-10834, 2019. DOI: 10.20964/2019.12.76

    Abstract: PdZn/C electrocatalysts were prepared by sodium borohydride utilized as reducing agent for activation methane in an acidic medium at room temperature and in a proton exchange membrane fuel cell (PEMFC) at 80°C. The materials prepared were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The diffractograms of the PdZn/C electrocatalysts showed only peaks associated with Pd face-centered cubic (fcc) structure. Cyclic voltammograms (CV) of all electrocatalysts after adsorption of methane shown an increment in current during the anodic scan, this effect was more pronounced for Pd(70)Zn(30)/C. In situ ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) experiments was not observed the formation of intermediates adsorbed for PdZn/C electrocatalysts, this behavior indicated that the methane oxidation occurs by parallel mechanisms. Polarization curves at 80°C in PEMFC show that Pd(90)Zn(10)/C has superior performance over the other electrocatalysts in methane oxidation.

    Palavras-Chave: methane; palladium; zinc; electrocatalysts; sodium compounds; borohydrides; reduction; oxidation; polarization; electrolytes; diagrams

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  • IPEN-DOC 26397

    QUEIROZ, CARLA M.S. ; MACHADO, ARTHUR P. ; PAIVA, ANA R.N. ; ANTONIASSI, RODOLFO M. ; VAZ, JORGE M. ; SPINACE, ESTEVAM V. . Active Pt/CeO2 catalysts prepared by an alcohol‑reduction process for low‑temperature CO‑PROX reaction. Materials for Renewable and Sustainable Energy, v. 8, n. 3, p. 1-8, 2019. DOI: 10.1007/s40243-019-0155-y

    Abstract: Pt/CeO2 catalysts were prepared with 0.5 and 1 wt% of Pt loadings by an alcohol-reduction process using a solution of ethylene glycol and water as a reducing agent and solvent. The obtained catalysts were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy. Transmission electron micrographs showed Pt nanoparticles with average sizes of 2.2 and 2.4 nm for Pt content of 0.5 and 1 wt%, respectively. The preferential oxidation of carbon monoxide in hydrogen-rich stream (CO-PROX reaction) was studied in the temperature range of 25–150 °C. Pt/CeO2 catalysts showed maximum CO conversions in the range of 80–98% and CO2 selectivity in the range of 50–70% at 50 °C.

    Palavras-Chave: catalysts; cerium; cerium oxides; platinum; alcohols; reduction; hydrogen; carbon monoxide; selective catalytic reduction

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  • IPEN-DOC 26398

    PAPAI, RODRIGO; FREITAS, MILLENA A.S. de; FONSECA, KARINA T. da; ALMEIDA, GILMAR A. de ; SILVEIRA, JOÃO R.F. da; SILVA, ANDRE L.N. da; FERREIRA NETO, JOÃO B.; SANTOS, CELIA A.L. dos; LANDGRAF, FERNANDO J.G.; LUZ, MACIEL S.. Additivity of optical emissions applied to neodymium and praseodymium quantification in metallic didymium and (Nd,Pr)-Fe-B alloy samples by low-resolution atomic emission spectrometry: an evaluation of the mathematical approach used to solve spectral interferences. Analytica Chimica Acta, v. 1085, p. 21-28, 2019. DOI: 10.1016/j.aca.2019.07.049

    Abstract: In this work, the effectiveness of a mathematical approach to solve the spectral interferences involved in the optical emission of two chemical species (neodymium and praseodymium) when using monochromators with low-resolution in atomic spectrometry is evaluated. Although recent technological advances have promoted spectrometers equipped with high-resolution monochromators, which have a great instrumental capability in the separation of nearby lines and consequently avoid spectral interferences, many laboratories still have old spectrometers installed with insufficient resolution to overcome such interferences. In order to evaluate a mathematical approach based on Lambert-Beer's Law, the optical emissions of neodymium and praseodymium were monitored on a low-resolution (200 pm) flame atomic emission spectrometry (F-AES). These two elements were strategically chosen as an application model because they exhibit similar physicochemical properties, joint occurrence in nature and because they are increasingly used in the manufacture of super-magnets, a material increasingly required by the high technology industry. The effectiveness of the mathematical approach was evaluated in three different ways: (i) by recovery of the analytes in synthetic mixtures containing known quantities of the species; (ii) by spike and recovery trials on a representative blend of dissolved samples and (iii) by comparing the results obtained with another analytical method: Inductively coupled plasma optical emission spectrometry (ICP-OES) with a higher spectral resolution. The results indicate the effectiveness of this simple mathematical approach, allow the “survival” of instruments equipped with low-resolution monochromators and demonstrate the applicability of this approach to spectral correction. In addition, this work contributes an analytical method for the quantification of neodymium and praseodymium in metallic alloy samples involved in the production of super-magnets, aiding in the strict quality control of these materials.

    Palavras-Chave: additives; emission; absorption spectroscopy; neodymium; praseodymium; spectra; interference; atoms

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  • IPEN-DOC 12314

    BOTTA, SERGIO B.; ANA, PATRICIA A. da; ZEZELL, DENISE M. ; POWERS, JOHN M.; MATOS, ADRIANA B.. Adhesion after erbium, chromium: yttrium-scandium-gallium-garnet laser aplication at three different irradiation conditions. Lasers in Medical Science, v. 24, n. 1, p. 67-73, 2009.

    Palavras-Chave: erbium; chromium; yttrium; scandium; gallium; garnets; laser radiation; teeth; caries; tissues; cooling; water; bonding

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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.

    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 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.

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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.

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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 25090

    FALCAO, R.B. ; DAMMANN, EDGAR D.C.C. ; ROCHA, C.J. ; DURAZZO, M. ; ICHIKAWA, R.U. ; MARTINEZ, L.G. ; BOTTA, W.J.; LEAL NETO, R.M. . An alternative route to produce easily activated nanocrystalline TiFe powder. International Journal of Hydrogen Energy, v. 43, n. 33, p. 16107-16116, 2018. DOI: 10.1016/j.ijhydene.2018.07.027

    Abstract: In this paper, an alternative process route to produce active nanocrystalline TiFe compound was investigated. First, TiH2 and Fe powders were dry co-milled in a planetary ball mill for 5e40 h. TiH2 was selected as precursor powder, instead of Ti powder, due its fragility, which has proved to be beneficial to decrease powders adherence on milling tools. In terms of loose powder mass, milling yields ranged from 90 to 95 wt.%. Next, milled powders were post-heated at 873 K under dynamic high-vacuum for TiFe synthesis reaction. First hydrogen absorption was verified in situ during the cooling process of samples (until the room temperature), being the amount of hydrogen absorbed and desorbed by this samples measured by automated Sievert's apparatus, under constant hydrogen flow rate of 9 cm3. min-1 (dynamic measurements). Besides to allowing the first absorption in situ, the investigated process route also allowed the production of the non-stoichiometric TiFe compound (rich in Ti) in samples milled for shorter times (5 and 10 h), both characteristics associated with maintaining the mechanical compound activity. Each sample absorbed hydrogen at 2 MPa during the cooling process, requiring no additional thermal activation cycles, since the samples milled for shorter times (mainly for 10 h) could absorb hydrogen for the first time more easily. However, the samples milled for longer times (25 and 40 h) shown better results in terms of reversible and storage capacities (0.73 and 0.94 wt.%, respectively).

    Palavras-Chave: nanostructures; powders; titanium hydrides; iron compounds; hydrides; milling; hydrogen storage

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  • IPEN-DOC 19227

    CHURA-CHAMBI, R.M.; CORDEIRO, Y.; MALAVASI, N.V.; LEMKE, L.S.; RODRIGUES, D.; MORGANTI, L. . An analysis of the factors that affect the dissociation of inclusion bodies and the refolding of endostatin under high pressure. Process Biochemistry, v. 48, n. 2, p. 250-259, 2013.

    Palavras-Chave: escherichia coli; proteins; hydrostatics; bacteria; inclusions; agglomeration; collagen; endothelium

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  • IPEN-DOC 19051

    MUCCILLO, R. ; MUCCILLO, E.N.S. . An experimental setup for shrinkage evaluation during electric field-assisted flash sintering: Application to yttria-stabilized zirconia. Journal of the European Ceramic Society, v. 33, n. 3, p. 515-520, 2013.

    Palavras-Chave: sintering; dilatometry; electric fields; impedance; scanning electron microscopy; yttrium oxides; zirconium oxides; grain growth; spectroscopy

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  • IPEN-DOC 26862

    GARCIA, PAULO R.A.F.; PRYMAK, OLEG; GRASMIK, VIKTORIA; PAPPERT, KEVIN; WLYSSES, WAGNER; OTUBO, LARISSA ; EPPLE, MATTHIAS; OLIVEIRA, CRISTIANO L.P.. An in situ SAXS investigation of the formation of silver nanoparticles and bimetallic silver–gold nanoparticles in controlled wet-chemical reduction synthesis. Nanoscale Advances, v. 2, n. 1, p. 225-238, 2020. DOI: 10.1039/c9na00569b

    Abstract: We present a study on the formation of silver (Ag) and bimetallic silver–gold (AgAu) nanoparticlesmonitored by in situ SAXS as well as by ex situ TEM, XRD and UV-vis analysis in a flow reactor at controlled reaction temperature. The formation mechanism of the nanoparticles is derived from the structural parameters obtained from the experimental data. The evolution of the average particle size of pure and alloyed nanoparticles shows that the particle growth occurs initially by a coalescence mechanism. The later growth of pure silver nanoparticles is well described by Ostwald ripening and for the alloyed nanoparticles by a process with a significantly slower growth rate. Additionally, the SAXS data of pure silver nanoparticles revealed two major populations of nanoparticles, the first one with a continuous crystal growth to a saturation plateau, and the second one probably with a continuous emergence of small new crystals. The particle sizes obtained by SAXS agree well with the results from transmission electron microscopy and X-ray diffraction. The present study demonstrates the capability of an in situ investigation of synthesis processes using a laboratory based SAXS instrument. Online monitoring of the synthesis permitted a detailed investigation of the structural evolution of the system.

    Palavras-Chave: nanoparticles; small angle scattering; x-ray diffraction; silver; bimetals; gold; monte carlo method; nanostructures; alloys

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  • IPEN-DOC 25206

    FREITAS, LUCAS F. de ; VARCA, GUSTAVO H.C. ; BATISTA, JORGE G. dos S. ; LUGAO, ADEMAR B. . An overview of the synthesis of gold nanoparticles using radiation technologies. Nanomaterials, v. 8, n. 11, 2018. DOI: 10.3390/nano8110939

    Abstract: At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.

    Palavras-Chave: gold; nanoparticles; gamma radiation; electron beams; x-ray sources; radiolysis; nanotechnology; medicine; diagnostic uses; ionizing radiations

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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.