Navegação Periódicos - Artigos por assunto "nanomaterials"

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  • IPEN-DOC 25710

    PERES, JOSE C.G.; HERRERA, CRISTHIANO da C. ; BALDOCHI, SONIA L. ; ROSSI, WAGNER de ; VIANNA JUNIOR, ARDSON dos S.. Analysis of a microreactor for synthesizing nanocrystals by computational fluid dynamics. Canadian Journal of Chemical Engineering, v. 97, n. 2, p. 594-603, 2019. DOI: 10.1002/cjce.23356

    Abstract: Microreactors eliminate batch-to-batch variability and allow better control over nanocrystal synthesis. A serpentine microreactor fabricated by femtosecond laser ablation is presented and characterized by computational fluid dynamics, since the micro channels show a trapezoidal cross-section mainly due to the relatively high numerical aperture of the focusing lens. Mixing, macro and micro, throughout the device was investigated for inlet flow rates between 10–500 mL min 1 and the injection of an inert tracer with the same transport properties of water. The simulation of the whole microreactor enabled the analysis of the formation and destruction of structures. For instance, secondary flows played a major role in mixing behaviour: small flow rates did not promote mixing of the tracer and a stream of pure water even after 43 curved segments, while they were perfectly mixed after 9 segments for higher flow rates. According to the mixing index, the maximum effect of convective mixing was achieved for an inlet flow rate of 250 mL min 1. Tracer dispersion and the mixing index guided a scale-up process of the microreactor, optimizing the number of curved segments while increasing total throughput. The upscaled design exhibited mixing saturation at 400 mL min 1 and promoted better control of residence time to allow nanocrystal growth.

    Palavras-Chave: lasers; ablation; nanomaterials; crystals; ; synthesis; laminar flow; mixing

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  • IPEN-DOC 25104

    JIMENEZ-VILLAR, ERNESTO ; XAVIER, M.C.S.; WETTER, NIKLAUS U. ; MESTRE, VALDECI; MARTINS, WELITON S.; BASSO, GABRIEL F.; ERMAKOV, V.A.; MARQUES, F.C.; SA, GILBERTO F. de. Anomalous transport of light at the phase transition to localization: strong dependence with incident angle. Photonics Research, v. 6, n. 10, p. 929-942, 2018. DOI: 10.1364/PRJ.6.000929

    Abstract: There has been a growing interest in disordered optical media in recent years due to their potential applications in solar collectors, random lasers, light confinement, and other advanced photonic functions. This paper studies the transport of light for different incidence angles in a strongly disordered optical medium composed of core-shell TiO2@Silica nanoparticles suspended in an ethanol solution. A decrease of optical conductance and an increase of absorption near the input border are reported when the incidence angle increases. The specular reflection, measured for the photons that enter the sample, is lower than the effective internal reflection undergone by the coherently backscattered photons in the exact opposite direction, indicating a nonreciprocal propagation of light. This study represents a novel approach in order to understand the complex physics involved at the phase transition to localization.

    Palavras-Chave: backscattering; titanium oxides; silica; optical properties; light transmission; quantum electrodynamics; nanomaterials; multiple scattering; light sources

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  • IPEN-DOC 22419

    SOUZA, EDITH M.M.; COSTA, WANDERLEY da; SILVA, LEONARDO G.A. ; WIEBECK, HELIO. Behavior of adhesion forces of the aqueous-based polychloroprene adhesive magnetically conditioned. Journal od Adhesion Science and Technology, v. 30, n. 15, p. 1689-1699, 2016.

    Palavras-Chave: adhesives; catalysis; additives; neoprene; carbon dioxide; catalysts; nanomaterials; magnetism

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  • IPEN-DOC 23966

    COSTA, WANDERLEY da; SOUZA, EDITH M.M.; SILVA, LEONARDO G.A. ; WIEBECK, HELIO. Behavior of adhesion forces of the aqueous-based polyurethane adhesive magnetically conditioned. Modern Chemistry & Applications, v. 4, n. 4, p. 1-8, 2016. DOI: 10.4172/2329-6798.1000190

    Abstract: This research presents a new proposal to water based adhesives manufacturing process, utilizing magnetic conditioning. Using this technique it is possible to increase the adhesion capacity between the adhesive and the substrate. The formulation proved to be efficient after the magnetic conditioning and without reactivation which also generated a significant alteration of the viscosity which was 350 mPa.s to 1100 mPa.s, without the necessity of the addition of any other product as thickener. If we compare the same adhesive formulation, with magnetic conditioning and without reactivation and an adhesive without magnetic conditioning and with reactivation, the increase of adhesion capacity was 42.11%, in the magnetically conditioning. When we verify the shear stresses in adhesive without reactivation, without magnetic conditioning and irradiated at 15 kGy we found an average of 3.29 × 105 Pa in the shear stresses, that is 2.16 times lower, compared with the average value found in the test specimens, magnetically conditioned, without reactivation, which was 7.11 × 105 Pa. If the non-ionizing radiation dose of 25 kGy passes, the shear stresses decrease considerably, regardless of the process, with or without magnetic conditioning has the consequence of breaking of the bonds of the polymeric matrix with the test specimens interface.

    Palavras-Chave: polyurethanes; adhesives; catalysis; additives; neoprene; carbon dioxide; catalysts; nanomaterials; magnetism

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  • IPEN-DOC 29613

    PACHECO, CAROLINE V.; PERES, RENATO M.; CARRIERI, GABRIELA; MINUSSI, GIULIA R.; ZAMBRANA, GUIDO P.; KANG, JESSICA S.H.; OLIVEIRA, RENE R. de ; LIMA, NELSON B. de ; BERNUSSI, AYRTON; WARZYWODA, JULIUSZ; MUNHOZ, ANTONIO H.. Cement-based composites incorporating pseudoboehmite nanomaterials. Journal of Materials in Civil Engineering, v. 35, n. 2, p. 04022413-1 - 04022413-11, 2023. DOI: 10.1061/(ASCE)MT.1943-5533.0004586

    Abstract: Pseudoboehmite is a hydrated aluminum oxyhydroxide obtained from inorganic precursors by the sol-gel process. It is used as a precursor to alumina and as a reinforcement in obtaining nanocomposites. Cement-reinforced composites with this nanomaterial were obtained in concrete and mortar. Pseudoboehmite with sodium polyacrylate was used to promote a deflocculation of pseudoboehmite particles, which tend to agglomerate in the material. The obtained material was added to the concrete to improve its workability and strength. The new concrete was characterized by slump tests and mechanical tests. Our results revealed that the incorporation of pseudoboehmite with sodium polyacrylate significantly increased the compressive strength and improved the workability of the concrete. Multiple experiments evaluated compressive strength, ultrasound speed, and nanomaterial characterization. Using the Weibull method in mortars, we verified that the pseudoboehmite brought visible benefits as the characteristic stress increased by 17.5%. This increase was observed with the addition of 3% by weight of pseudoboehmite.

    Palavras-Chave: nanomaterials; aluminium compounds; building materials; mortars; concretes; sodium; polyacrylates

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  • IPEN-DOC 25763

    QUEIROZ, FERNANDA M.; DONATUS, UYIME ; RAMIREZ, OSCAR M.P.; ARAUJO, JOAO V. de S. ; VIVEIROS, BARBARA V.G. de ; LAMAKA, SVIATLANA; ZHELUDKEVICH, MIKHAIL; MASOUMI, MOHAMMAD; VIVIER, VINCENT; COSTA, ISOLDA ; MELO, HERCILIO G. de. Effect of unequal levels of deformation and fragmentation on the electrochemical response of friction stir welded AA2024-T3 alloy. Electrochimica Acta, v. 313, p. 271-281, 2019. DOI: 10.1016/j.electacta.2019.04.137

    Abstract: The effect of unequal levels of deformation and fragmentation on the electrochemical response of friction stir welded AA2024-T3 has been investigated using electron backscatter diffraction, scanning electron microscopy, global and localized electrochemical techniques. The friction stir welding process introduced unequal distribution and fragmentation of coarse intermetallic particles, such that more clusters of these particles were present in the thermomechanically affected zone of the weld. This resulted in a higher susceptibility to severe localized corrosion in this region when compared with the others. Results from electrochemical measurements using a microcell could not be clearly correlated with the corrosion behaviour because no significant differences were observed using these techniques. On the other hand, LEIS and SVET results were in agreement and correlated with the corrosion evolution at the surfaces of the tested samples.

    Palavras-Chave: aluminium alloys; electrochemistry; electrochemical cells; microstructure; corrosion; friction welding; cluster analysis; methylene blue; nanomaterials; optical properties; staphylococcus; inactivation; shells; bacteria

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  • IPEN-DOC 28681

    DAS, AVISHEK; RAPOSO, GISELE C.C.; LOPES, DANIELA S.; SILVA, EVAIR J. da; CARNEIRO, VANDA S.M.; MOTA, CLAUDIA C.B. de O.; AMARAL, MARCELLO M.; ZEZELL, DENISE M. ; BARBOSA-SILVA, RENATO; GOMES, ANDERSON S.L.. Exploiting nanomaterials for optical coherence tomography and photoacoustic imaging in nanodentistry. Nanomaterials, v. 12, n. 3, p. 1-22, 2022. DOI: 10.3390/nano12030506

    Abstract: There is already a societal awareness of the growing impact of nanoscience and nanotechnology, with nanomaterials (with at least one dimension less than 100 nm) now incorporated in items as diverse as mobile phones, clothes or dentifrices. In the healthcare area, nanoparticles of biocompatible materials have already been used for cancer treatment or bioimaging enhancement. Nanotechnology in dentistry, or nanodentistry, has already found some developments in dental nanomaterials for caries management, restorative dentistry and orthodontic adhesives. In this review, we present state-of-the-art scientific development in nanodentistry with an emphasis on two imaging techniques exploiting nanomaterials: optical coherence tomography (OCT) and photoacoustic imaging (PAI). Examples will be given using OCT with nanomaterials to enhance the acquired imaging, acting as optical clearing agents for OCT. A novel application of gold nanoparticles and nanorods for imaging enhancement of incipient occlusal caries using OCT will be described. Additionally, we will highlight how the OCT technique can be properly managed to provide imaging with spatial resolution down to 10′s–100′s nm resolution. For PAI, we will describe how new nanoparticles, namely TiN, prepared by femtosecond laser ablation, can be used in nanodentistry and will show photoacoustic microscopy and tomography images for such exogenous agents.

    Palavras-Chave: nanomaterials; dentistry; biological materials; photoacoustic effect; optics; optics; optics; tomography

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  • IPEN-DOC 22387

    SOUZA, ADELMO S.; NUNES, LUIZ A.O.; SILVA, IVAN G.N.; OLIVEIRA, FERNANDO A.M.; LUIZ, LEONIS L. da; BRITO, HERMI F.; FELINTO, MARIA C.F.C. ; FERREIRA, RUTE A.S.; JUNIOR, SEVERINO A.; CARLOS, LUIS D.; MALTA, OSCAR L.. Highly-sensitive Eusup(3+) ratiometric thermometers based on excited state absorption with predictable calibration. Nanoscale, v. 8, n. 9, p. 5327-5333, 2016.

    Palavras-Chave: europium ions; thermometers; absorption; calibration; yttrium oxides; emission spectra; synthesis; nanomaterials; doped materials

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  • IPEN-DOC 27703

    SENIWAL, BALJEET; FREITAS, LUCAS F. ; MENDES, BRUNO M.; LUGAO, ADEMAR B. ; KATTI, KATTESH V.; FONSECA, TELMA C.F.. In silico dosimetry of low-dose rate brachytherapy using radioactive nanoparticles. Physics in Medicine and Biology, v. 66, n. 4, p. 1-13, 2021. DOI: 10.1088/1361-6560/abd671

    Abstract: Purpose. Nanoparticles (NPs) with radioactive atoms incorporated within the structure of the NP or bound to its surface, functionalized with biomolecules are reported as an alternative to low-dose-rate seed-based brachytherapy. In this study, authors report a mathematical dosimetric study on low-dose rate brachytherapy using radioactive NPs. Method. Single-cell dosimetry was performed by calculating cellular S-values for spherical cell model using Au-198, Pd-103 and Sm-153 NPs. The cell survival and tumor volume versus time curves were calculated and compared to the experimental studies on radiotherapeutic efficiency of radioactive NPs published in the literature. Finally, the radiotherapeutic efficiency of Au-198, Pd-103 and Sm-153 NPs was tested for variable: administered radioactivity, tumor volume and tumor cell type. Result. At the cellular level Sm-153 presented the highest S-value, followed by Pd-103 and Au-198. The calculated cell survival and tumor volume curves match very well with the published experimental results. It was found that Au-198 and Sm-153 can effectively treat highly aggressive, large tumor volumes with low radioactivity. Conclusion. The accurate knowledge of uptake rate, washout rate of NPs, radio-sensitivity and tumor repopulation rate is important for the calculation of cell survival curves. Self-absorption of emitted radiation and dose enhancement due to AuNPs must be considered in the calculations. Selection of radionuclide for radioactive NP must consider size of tumor, repopulation rate and radiosensitivity of tumor cells. Au-198 NPs functionalized with Mangiferin are a suitable choice for treating large, radioresistant and rapidly growing tumors.

    Palavras-Chave: nanoparticles; radioactive materials; radioactivity; brachytherapy; dose rates; low dose irradiation; dosimetry; radiotherapy; nanomaterials; neoplasms

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  • IPEN-DOC 21673

    SILVA, IVAN G.N.; MUSTAFA, DANILO; FELINTO, MARIA C.F.C. ; FAUSTINO, WAGNER M.; TEOTONIO, ERCULES E.S.; MALTA, OSCAR L.; BRITO, HERMI F.. Low temperature synthesis of luminescent REsub(2)Osub(3):Eusup(3+) nanomaterials using trimellitic acid precursors. Journal of the Brazilian Chemical Society, v. 26, n. 12, p. 2629-2639, 2015.

    Palavras-Chave: photoluminescence; synthesis; nanomaterials; thermal gravimetric analysis; scanning electron microscopy; yttrium oxides; gadolinium oxides; lutetium oxides; europium ions

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  • IPEN-DOC 22439

    PAULA, V.G. de; SILVA, L.M. da; SANTOS, A.O. dos; LANG, R.; OTUBO, L. ; COELHO, A.A.; CARDOSO, L.P.. Magnetocaloric effect and evidence of superparamagnetism in GdAlsub(2) nanocrystallites: A magnetic structural correlation. Physical Review B, v. 93, n. 9, p. 094427-1 - 094427-9, 2016.

    Palavras-Chave: superparamagnetism; gadolinium; aluminium; nanomaterials; crystals; correlations; crystal structure; magnetic properties; x-ray diffraction; transmission electron microscopy

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  • IPEN-DOC 25796

    CORDEIRO, THIAGO da S. ; AMARAL, MARCELLO M.; MATOS, RICARDO A. de; SILVA, FLAVIA R.O. ; VIEIRA JUNIOR, NILSON D. ; COURROL LILIA C.; ROSSI, WAGNER de ; SAMAD, RICARDO E. . Modifying the second order dispersion of femtosecond laser pulses to crack silver nanoparticles and control their dimensions. Optics and Laser Technology, v. 118, p. 1-7, 2019. DOI: 10.1016/j.optlastec.2019.04.034

    Abstract: The potential application of metallic nanoparticles had been attracting attention and interest from different areas of academia and industry. The nanoparticles properties and applications depend heavily on their dimension and shape, thus special interest is aimed to controlling the nanoparticles sizes. Ultrashort laser pulses are known to change metallic nanoparticles characteristics, but the interaction mechanism is still not completely understood. In this work we reduced the dimension of silver nanoparticles with ultrashort pulses and demonstrated that there is a dependence of the particles size on the second order dispersion introduced in the pulses, which became smaller as the dispersion becomes more negative. Based on the results, we propose that the Coulomb explosion that reduces the nanoparticles size is predominantly initiated by multiphotonic ionization for the intensities used (1014 W/cm2).

    Palavras-Chave: nanoparticles; nanomaterials; lasers; silver; spectroscopy

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  • IPEN-DOC 23050

    GROSSO, ROBSON L. ; MUCCILLO, ELIANA N.S. ; CASTRO, RICARDO H.R.. Phase stability in scandia-zirconia nanocrystals. Journal of the American Ceramic Society, v. 100, n. 5, p. 2199-2208, 2017. DOI: 10.1111/jace.14710

    Abstract: Scandia-zirconia system has great technological interest as it has the highest ionic conductivity among doped zirconia ceramics. However, polymorphism is the most important limiting factor for application of this material. Considering that there is a strong grain size dependence on phase transitions in this class of materials, mapping out the stable polymorph as a function of grain size and composition may lead to more efficient compositional design. In this article, the phase stability of zirconia-scandia nanocrystals was investigated based on experimental thermodynamic data. Exploiting recent advances in microcalorimetry, reliable surface energy data for five polymorphs of scandia-zirconia system: monoclinic, tetragonal, cubic, rhombohedral b and c are reported for the first time. Combining surface energy values with bulk enthalpy data obtained from oxide melt drop solution calorimetry allowed us to create a predictive phase stability diagram that shows the stable zirconia polymorph as a function of composition and grain size of the specimen within the range of 0-20 mol% scandia.

    Palavras-Chave: phase stability; scandium alloys; zirconium alloys; nanomaterials; nanocrystals; x-ray diffraction; ionic conductivity

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  • IPEN-DOC 24742

    KHAN, LATIF U.; ZAMBON, LUIS F.M.; SANTOS, JACINETE L.; RODRIGUES, RODRIGO V.; COSTA, LUELC S.; MURACA, DIEGO; PIROTA, KLEBER R.; FELINTO, MARIA C.F.C. ; MALTA, OSCAR L.; BRITO, HERMI F.. Red-emitting magnetic nanocomposites assembled from Ag-decorated Fe3O4@SiO2 and Y2O3:Eu3+: impact of iron-oxide/silver nanoparticles on Eu3+ emission. Chemistryselect, v. 3, n. 4, p. 1157-1167, 2018. DOI: 10.1002/slct.201702478

    Abstract: The new multistep approach for co-assembling magnetic iron oxide nanoflowers with red-emitting Y2O3:Eu3+ to form luminescent and magnetic nanocomposites was reported. The Fe3O4 core prepared by solvothermal method was layered by SiO2 shell and decorated with small size spherical Ag nanoparticles as well as further coated with Y2O3:Eu3+ luminophore. The nanoflower shape Fe3O4 core of size similar to 110 nm and crystalline cubic structure of bifunctional iron-oxide@Y2O3:Eu3+, Fe3O4@SiO2@Y2O3:Eu3+ and Fe3O4@SiO2-Ag@Y2O3:Eu3+ (1 mol%) nanomaterials were confirmed from X-rays diffraction, EDS spectra and transmission electron microscopy (TEM) images. The static magnetic measurements supported and manifested nonsuperparamagnetic behavior of the materials at 300 K. The iron oxides are usually luminescence quenchers. In order to rationalize this effect, their optical properties based on their emission spectral data and luminescence decay curves were studied. Experimental intensity parameters (Wl), lifetimes (t), intrinsic quantum yield (Q(Ln)(Ln)) as well as radiative (Arad) and non-radiative (Anrad) decay rates were calculated to probe the local chemical environment of the Eu3+ ion and to better understand the phenomena of iron oxide induced luminescence quenching. The highest value of the intrinsic quantum yield (Q(Ln)(Ln) = 74%) for the alpha-Fe2O3@Y2O3:Eu3+ (1 mol%) among all the luminescent and magnetic nanocomposites suggests that alpha-Fe2O3 phase induces a lower luminescence quenching then Fe3O4/g-Fe2O3. The SiO2 thin layer leads to improve the luminescence efficiency, whereas the Ag nanoparticles act as luminescence quencher. These novel Eu3+ nanomaterials may act as a red emitting layer for magnetic and light converting molecular devices.

    Palavras-Chave: iron oxides; nanocomposites; photoluminescence; silver oxides; magnetism; nanomaterials; europium; doped materials; yttrium

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  • IPEN-DOC 29599

    NEGAHDARY, MASOUD; HIRATA, MARIO H.; SAKATA, SOLANGE K. ; CICONELLI, ROZANA M.; BASTOS, GISELE M.; BORGES, JESSICA B.; THUROW, HELENA S.; SILVEIRA JUNIOR, ALCEU T.; SAMPAIO, MARCELO F.; GUIMARAES, LARISSA B.; MAEDA, BRUNO S.; ANGNES, LUCIO. Sandwich-like electrochemical aptasensing of heat shock protein 70 kDa (HSP70): application in diagnosis/prognosis of coronavirus disease 2019 (COVID-19). Analytica Chimica Acta, v. 1242, p. 1-10, 2023. DOI: 10.1016/j.aca.2022.340716

    Abstract: In this research, by using aptamer-conjugated gold nanoparticles (aptamer-AuNPs) and a modified glassy carbon electrode (GCE) with reduced graphene oxide (rGO) and Acropora-like gold (ALG) nanostructure, a sandwich-like system provided for sensitive detection of heat shock protein 70 kDa (HSP70), which applied as a functional biomarker in diagnosis/prognosis of COVID-19. Initially, the surface of the GCE was improved with rGO and ALG nanostructures, respectively. Then, an aptamer sequence as the first part of the bioreceptor was covalently bound on the surface of the GCE/rGO/ALG nanostructures. After adding the analyte, the second part of the bioreceptor (aptamer-AuNPs) was immobilized on the electrode surface to improve the diagnostic performance. The designed aptasensor detected HSP70 in a wide linear range, from 5 pg mL−1 to 75 ng mL−1, with a limit of detection (LOD) of ∼2 pg mL−1. The aptasensor was stable for 3 weeks and applicable in detecting 40 real plasma samples of COVID-19 patients. The diagnostic sensitivity and specificity were 90% and 85%, respectively, compared with the reverse transcription-polymerase chain reaction (RT-PCR) method.

    Palavras-Chave: gold; nanomaterials; coronaviruses; electrochemistry; electrodes; graphene

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  • IPEN-DOC 29716

    AMARO, AUGUSTO A.; MATTOS, GUILHERME R. da S.; NISHIMURA, MARCOS V. de M.; DIPOLD, JESSICA ; WETTER, NIKLAUS U. ; KASSAB, LUCIANA R.P.. Silver nanoclusters tunable visible emission and energy transfer to Yb3+ Ions in co-doped GeO2-PbO glasses for photonic applications. Nanomaterials, v. 13, n. 7, p. 1-15, 2023. DOI: 10.3390/nano13071177

    Abstract: This work investigates the optical properties of Yb3+ ions doped GeO2 -PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices.

    Palavras-Chave: ytterbium ions; silver; nanomaterials; germanates; glass; photoluminescence

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  • IPEN-DOC 25826

    FONTES, ERIC H. ; RAMOS, CARLOS E.D. ; NANDENHA, JULIO ; PIASENTIN, RICARDO M. ; OLIVEIRA NETO, ALMIR ; LANDERS, RICHARD. Structural analysis of PdRh/C and PdSn/C and its use as electrocatalysts for ethanol oxidation in alkaline medium. International Journal of Hydrogen Energy, v. 44, n. 2, p. 937-951, 2019. DOI: 10.1016/j.ijhydene.2018.11.049

    Abstract: The Pd/C, PdRh(50:50)/C and PdSn(50:50)/C nanomaterials were used as electrocatalysts for ethanol (EtOH) oxidation in Direct Ethanol Fuel Cell (DEFC) in an alkaline medium. This work aims to provide a complete physical characterization of the nanomaterials, elucidate the bifunctional mechanism concerning ethanol oxidation reaction and understand the influence of carbon e metal bonding in the electrochemical activity. These nanomaterials were investigated by X-ray photoelectron spectroscopy (XPS) and revealed that the atomic percentage of the surface is different of those obtained by Energy Dispersive X-ray spectroscopy (EDS). Raman spectroscopy showed a bonding between palladium and carbon atoms which can play a decisive role in the performance of the materials. Attenuated Total Reflectance technique coupled to the Fourier Transform Infrared spectroscopy (ATR-FTIR) made possible to investigate the oxidation products originated by the ethanol oxidation, and all the electrocatalysts showed the presence of acetaldehyde, carbonate ions, acetate and carbon dioxide, suggesting that the mechanism of oxidation is incomplete. Among all the nanomaterials studied, PdSn(50:50)/C showed the best electrochemical and Fuel Cell's results. It is about 33% better than Pd/C. The micrographs obtained by Transmission Electron Microscopy (TEM) revealed some agglomerate regions, but they are consistent with the literature data.

    Palavras-Chave: electrocatalysts; ethanol; x-ray diffraction; direct ethanol fuel cells; oxidation; nanomaterials; raman spectroscopy

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  • IPEN-DOC 21309

    CARVALHO, JOSE M.; RODRIGUES, LUCAS C.V.; FELINTO, MARIA C.F.C. ; NUNES, LUIZ A.O.; HOLSA, JORMA; BRITO, HERMI F.. Structure-property relationship of luminescent zirconia nanomaterials obtained by sol-gel method. Journal of Materials Science, v. 50, p. 873-881, 2015.

    Palavras-Chave: structure-activity relationships; luminescence; zirconium oxides; nanomaterials; sol-gel process

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  • IPEN-DOC 21677

    ALCANTARA, RAQUEL R. ; IZIDORO, JULIANA C. ; FUNGARO, DENISE A. . Synthesis and characterization of surface modified zeolitic nanomaterial from coal fly ash. International Journal of Materials Chemistry and Physics, v. 1, n. 3, p. 370-377, 2015.

    Palavras-Chave: coal; fly ash; surfactants; surface air; modifications; zeolites; nanomaterials; thermal power plants; power generation; combustion

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  • IPEN-DOC 29077

    CARMO, JOSE V.C. do; BEZERRA, RITA de C.F.; TEHAUACANERO-CUAPA, SAMUEL; RODRIGUEZ-AGUADO, E.; LANG, ROSSANO; CAMPOS, ADRIANA F.; DUARTE, GIAN; SARAIVA, GILBERTO D.; OTUBO, LARISSA ; OLIVEIRA, ALCINEIA C.; RODRIGUEZ-CASTELLON, E.. Synthesis of tailored alumina supported Cu-based solids obtained from nanocomposites: catalytic application for valuable aldehyde and ketones production. Materials Chemistry and Physics, v. 292, p. 1-18, 2022. DOI: 10.1016/j.matchemphys.2022.126800

    Abstract: A tailored nanostructured CuO–ZnO/Al2O3 catalyst was obtained from nanocomposites via sonochemical route through core/shell assisted by reverse micelle synthesis. The as-synthesized nanocomposites consisted of Cu, Zn and Al domains coated by a lauric acid shell structure with controlled physicochemical properties. Combining these features, a porous CuO–ZnO/Al2O3 supported catalyst was obtained from CuZnAl@C nanocomposite, in which Cu and Zn oxide nanoparticles interacted quite strongly with alumina. In this study, a nanostructured CuO–ZnO/Al2O3 was applied to oxidize ethylbenzene in the presence of H2O2. Catalytic results further demonstrated that the nanostructured solid had ethylbenzene conversion superior to 20% and good selectivities to acetophenone, benzaldehyde and benzoic acid compared to a benchmark CuZnAl catalyst obtained by the sol-gel method.

    Palavras-Chave: porous materials; aluminium oxides; nanocomposites; oxidation; nanomaterials; copper alloys

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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.

O Repositório Digital do IPEN é um equipamento institucional de acesso aberto, criado com o objetivo de reunir, preservar, disponibilizar e conferir maior visibilidade à Produção Científica publicada pelo Instituto, desde sua criação em 1956.

Operando, inicialmente como uma base de dados referencial o Repositório foi disponibilizado na atual plataforma, em junho de 2015. No Repositório está disponível o acesso ao conteúdo digital de artigos de periódicos, eventos, nacionais e internacionais, livros, capítulos, dissertações, teses e relatórios técnicos.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.