Navegação por assunto "nanoparticles"

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  • IPEN-DOC 23168

    GALANTE, RAQUEL; REDIGUIERI, CAROLINA F.; KIKUCHI, IRENE S.; VASQUEZ, PABLO A.S. ; COLACO, ROGERIO; SERRO, ANA P.; PINTO, TEREZINHA J.A.. About the sterilization of chitosan hydrogel nanoparticles. Plos One, v. 11, n. 12, 2016. DOI: 10.1371/journal.pone.0168862

    Abstract: In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

    Palavras-Chave: sterilization; oligosaccharides; hydrogels; nanoparticles; drug delivery; biological materials

  • IPEN-DOC 26281

    PAES, SUANE C.; CORREA, BRUNO S.; SENA, CLEIDILANE; COSTA, MESSIAS S.; CABRERA-PASCA, GABRIEL A.; CARBONARI, ARTUR W. ; SAIKI, MITIKO . Açaí oil as an alternative in the synthesis and coating of iron oxide nanoparticles. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2437-2442.

    Abstract: In the last decades, nanotechnology studies have attracted the attention of researchers from various fields, engineering, chemistry, physics, medicine, environment. Medicine, nanomedicine, the major advances in the diagnosis and therapies of diseases, such as magnetic resonance imaging and the treatment of cancer by hyperthermia, respectively. Nanomaterials for such biomedical applications should have size control of less than 20 nm, crystal structure and well-defined morphology. Thus, as nanoparticles of iron oxide (Fe3O4) is one of the materials most studied for such applications. Thus, iron oxide nanoparticles were synthesized by variation of the thermal decomposition method, which is described as one of the best quality nanoparticle synthesis tools. During the synthesis, we used açaí oil, rich in fatty acids, palmitoleic, linoleic and palmitic, as a process of synthesis and coating of nanoparticles, making them biocompatible. The açaí oil was made by the supercritical extraction method, where the product can be obtained pure, free of solvents. The samples were characterized by X-ray diffraction (XRD) and the magnetite phase (Fe3O4) was identify through the position of the intensity peaks. The nanoparticles present spherical morphology with a diameter of 3 to 10 nm, observed through transmission electron microscopy (TEM) images. In addition, neutron analysis (NAA) determined that the samples had a concentration of 74.93% Fe3O4 and a remaining database is related to the coating of sample nanoparticles as potentiated for biomedical applications.

    Palavras-Chave: biology; coatings; concentration ratio; grain size; iron oxides; medicine; morphology; nanoparticles; neutron activation analysis; transmission electron microscopy; vegetable oils

  • IPEN-DOC 14870

    ODA, HUGO T.Y. ; YAMAURA, MITIKO . Adsorção do corante reativo Laranja 16 pela quitosana magnética. In: PROGRAMA INSTITUCIONAL DE BOLSAS DE INICIAÇÃO CIENTÍFICA, 14.; PROGRAMA DE BOLSAS E INICIAÇÃO CIENTÍFICA CNEN, 5., 5-6 de novembro, 2008, São Paulo, SP. Resumo expandido... 2008. p. 153-154.

    Palavras-Chave: adsorption; dyes; spectrophotometry; polymers; nanoparticles; separation processes; magnetic materials; adsorption isotherms; bioadsorbents

  • IPEN-DOC 25111

    CUNICO, PATRICIA ; KUMAR, ANU; ALCANTARA, RAQUEL R. ; FUNGARO, DENISE A. . Adsorption of solophenyl dyes from aqueous solution by modified nanozeolite from bottom ash and its toxicity to C. dubia. Current Nanomaterials, v. 2, n. 2, p. 95-103, 2017. DOI: 10.2174/2405461503666180201152351

    Abstract: Background: It is known that wastewater from textile industries are responsible for producing large amounts of highly contaminated effluents by various types of synthetic dyes. These compounds can be toxic, and in some cases, are carcinogenic and mutagenic and its removal is recommended. Application: In the area of water purification, nanomaterials have been applied for removal of several compounds. Of the four classes of nanomaterials, zeolites have demonstrated good results for the removal of dyes. Nanozeolite synthesized from bottom ash and modified with hexadecyltrimethylamonium (ZMB) was used as adsorbent to removal of Solophenyl Navy (SN), Solophenyl Turquoise (ST) and their hydrolyzed forms (SNH and STH, respectively) from simulated textile wastewater. Method: The physical-chemical characterization of materials was presented by using relevant analytical methods (XRD, SEM, BET surface area, etc.). Effects of parameters such as initial dye concentration, contact time and equilibrium adsorption were evaluated. The adsorption kinetics followed the pseudo-second-order model. Results: Langmuir isotherm model shows the best fit for most dyes-ZMB systems. In order to identify if ZMB presented toxicity for the environment, bioassay and toxicity identification evaluation (TIE) with C. dubia were performed. The leached of ZMB was toxic to daphinids (11.3 TU). Conclusion: TIE results appointed that the main cause of the toxicity could be due the surfactant and metal ions presents in aqueous solution.

    Palavras-Chave: toxicity; textile industry; waste water; nanoparticles; zeolites; copper; dyes; adsorption

  • IPEN-DOC 27828

    PARRA, DUCLERC F. ; MARCHINI, LEONARDO G. ; KOMATSU, LUIZ G.H. ; OLIVEIRA, CAMILA B. de ; OLIANI, WASHINGTON L. ; RANGARI, VIJAYA K.. AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect. SN Applied Sciences, v. 3, n. 4, 2021. DOI: 10.1007/s42452-021-04365-2

    Abstract: This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO2 NPs (silver/Zinc oxide/SiO2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique (SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus, are reported and these results showed potential application in health care products.

    Palavras-Chave: gamma radiation; irradiation; antibiotics; nanoparticles; silver; processing; thermoplastics

  • IPEN-DOC 21212

    GONCALVES, KARINA de O.; SILVA, MONICA N. da; SICCHIERI, LETICIA B. ; SILVA, FLAVIA R. de O. ; MATOS, RICARDO A. de; COURROL, LILIA C. . Aminolevulinic acid with gold nanoparticles: a novel theranostic agent for atherosclerosis. Analyst, v. 140, n. 6, p. 1974-1980, 2015.

    Palavras-Chave: aminolevulinic acid; gold; nanoparticles; arteriosclerosis; polyethylene glycols; rabbits; porphyrins; fluorescence spectroscopy; histological techniques; biochemistry; animals

  • IPEN-DOC 26399

    ROVANI, SUZIMARA ; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A. . An alternative and simple method for the preparation of bare silica nanoparticles using sugarcane waste ash, an abundant and despised residue in the Brazilian industry. Journal of the Brazilian Chemical Society, v. 30, n. 7, p. 1524-1533, 2019. DOI: 10.21577/0103-5053.20190049

    Abstract: Sugarcane waste ash, a Si-rich waste product, is generated in large quantities and creates a serious disposal problem in the Brazilian ethanol-sugar industry, affecting the environment and public health. Here, a simple method capable of generating bare silica nanoparticles utilizing this residue is demonstrated. Firstly, the crystalline silica present in sugarcane waste ash (SWA) was converted into amorphous by melting a mixture of sodium hydroxide and SWA at 550 °C for 1 h. The silica nanoparticles (SiO2NPs) were formed by lowing pH. This production process of SiO2NPs from SWA was optimized varying the ash:NaOH mass ratio, increasing the silica extraction up to 96%. The sample’s composition was characterized by total X-ray fluorescence spectroscopy, morphology and physical-chemical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, specific surface area measurements, Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), followed by use as adsorbent for the removal of methylene blue dye. With this process of extraction, nanoparticles smaller than 100 nm were generated, with a surface area of 63 m2 g-1 and a maximum adsorption capacity of 37 mg g-1 for methylene blue. The results indicate a successful process for obtaining an adsorbent from an industrial waste product using a cost effective and rapid synthesis procedure rendering renewable product.

    Palavras-Chave: sugar cane; wastes; adsorbents; silica; nanoparticles; ethanol fuels; ashes; sodium hydroxides; agriculture; agricultural wastes

  • 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

  • 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

  • IPEN-DOC 26347

    MOREIRA, PRISCILA G. ; STEFANIAK, IZABELA ; ROCHA, MARCELO S. . Analysis of the thermal conductivity of the aqueous-based TiO2 nanofluid for nuclear applications. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 4515-4524.

    Abstract: This work aims to investigate the thermophysical properties of T iO 2 nanofluids in water base experimentally and also comparing results to the literature. Exis ting studies indicate that nanofluids presents increase in thermal conductivity compared to the base fluid which in this study will be water, thus, can be classified as promising fluids for heat transport applications. As the proposal is to use it in nuclea r applications, the survey of experimen tal measurements was performed before and after irradiation in the IPEN installations to verify the effect of ionizing radiation on the properties of nanofluids. Thermal conductivity , viscosity and some visualization of nanopar ticles in SEM were carried out in order to understand the behavior of radiation influence on nanofluids and it properties.

    Palavras-Chave: heat transfer; ionizing radiations; nanofluids; nanoparticles; radiation effects; scanning electron microscopy; thermal conductivity; titanium oxides; viscosity; water

  • IPEN-DOC 26718

    JACOVONE, RAYNARA M.S. ; SOARES, JAQUELINE J.S. ; SOUSA, THAINA S. ; SILVA, FLAVIA R.O. ; GARCIA, RAFAEL H.L. ; NGUYEN, HANG N.; RODRIGUES, DEBORA F.; SAKATA, SOLANGE K. . Antibacterial activity of silver/reduced graphene oxide nanocomposite synthesized by sustainable process. Energy, Ecology and Environment, v. 4, n. 6, p. 318-324, 2019. DOI: 10.1007/s40974-019-00136-3

    Abstract: Traditional methods to incorporate metals into graphene oxide (GO) usually require toxic reagents or high temperatures. This study proposes an innovative and sustainable method to incorporate silver (Ag) into graphene oxide using electron beam and evaluate its antibacterial activities. The method is based on green synthesis, without toxic reagents or hazardous wastes, and can be carried out at room temperature, in short reaction times. To synthesize the Ag/rGO nanocomposite, a water/isopropanol solution with dispersed graphene oxide and silver nitrate was submitted to a dose range from 150 to 400 kGy. The product was characterized by thermogravimetry analysis, X-ray diffraction and transmission electron microscopy. The antibacterial activity of Ag/rGO was observed against Gram-negative Escherichia coli by plate count method and atomic force microscopy. The results showed that concentrations as low as 100 lg/mL of produced Ag/rGO were enough to inactivate the cells.

    Palavras-Chave: graphene; nanocomposites; antimicrobial agents; atomic force microscopy; silver; nanoparticles; electron beams; oxides; sustainability; thermal gravimetric analysis; bacteria; antibiotics; escherichia coli

  • IPEN-DOC 27124

    COURROL, LILIA C.; ESPINOZA-CULUPÚ, ABRAHAM; SILVA JUNIOR, PEDRO I. da; GONÇALVES, KARINA de O.; SILVA, FLAVIA R. de O. ; BORGES, MONAMARIS M.. Antibacterial and antitumoral activities of the spider acylpolyamine Mygalin silver nanoparticles. BioNanoScience, v. 10, n. 2, p. 463-472, 2020. DOI: 10.1007/s12668-020-00738-w

    Abstract: Mygalin is a synthetic analog of polyamine spermidine isolated from spider hemocytes. Polyamines show potential therapeutic activity against a wide range of human diseases such as cancer and microbial infections. In this work, we analyzed the antibacterial and antitumoral activities of Mygalin silver nanoparticles synthesized by the photoreduction method. The formation and distribution of MygAgNPs were confirmed by UV-visible spectroscopy, zeta potential, and transmission electron microscopy. The obtained nanoparticles were mostly spherical with a particle size distribution in the range of ~ 10–60 nm. We have demonstrated that MygAgNPs increased the effectiveness of the native Mygalin by approximately 6400-fold. Cytotoxicity tests were performed, and it was possible to reach a concentration that was not toxic to healthy cells (NHI-3T3) and at the same time toxic to the tumor cell line (MCF-7). The obtained results suggest that this system shows potential enhanced antibacterial activity against Escherichia coli, DH5α and anticancer activity against MCF-7 cell line.

    Palavras-Chave: drugs; neoplasms; antibiotics; spiders; silver; nanoparticles; cell cultures; drugs; amines; bacteria

  • IPEN-DOC 27589

    GONCALVES, FLAVIA; CAMPOS, LUIZA M. de P. ; SANCHES, LUCIANA K.F.; SILVA, LARISSA T.S.; SANTOS, TAMIRIS M.R. dos ; VARCA, GUSTAVO H.C. ; LOPES, DIANA P.; COGO-MULLER, KARINA; PARRA, DUCLERC F. ; BRAGA, ROBERTO R.; SANTOS, MARCELO dos; BOARO, LETICIA C.C.. Antimicrobial activity and physicochemical performance of a modified endodontic sealer / Atividade antimicrobiana e desempenho físico-químico de um cimento endodôntico modificado. Research, Society and Development, v. 9, n. 11, p. 1-16, 2020. DOI: 10.33448/rsd-v9i11.9401

    Abstract: Introduction: this study aimed to evaluate the antimicrobial and physicochemical properties of a commercial endodontic sealer modified by the addition of montmorillonite (MMT) nanoparticles loaded with two different drugs: chlorhexidine (CHX) or metronidazole (MET). Methods: 5 wt% MMT/CHX or MMT/MET nanoparticles were added to the sealer AH-Plus. The experimental materials were evaluated for drug release, antimicrobial activity, flow, flexural strength, and flexural modulus. Data were subjected to one-way ANOVA, Kruskal-Wallis, and Mann-Whitney tests. Results: The drug incorporation into MMT particles was 9% and 10% for CHX and MET, respectively. At 20 days after manipulation, 16.5% of the drug was released by the sealer with MMT/MET and 0.4% by MMT/CHX. The addition of both nanoparticles decreased the flow of materials, but they were still in compliance with ISO 6876-2012. The conversion, flexural strength, and flexural modulus of MMT/MET (87%, 37±7 MPa, 2.3 GPa) and MMT/CHX (78%, 29±2 MPa, 2.7 GPa) were similar in both groups but lower than in the control group (100%, 54±7 MPa, 4.0±0.7 GPa). Both experimental materials were able to form an inhibition halo for E. faecalis bacteria (CHX: 4.8±1.4 and MET: 4.0±1.6 mm), whereas the control group did not inhibit the microorganism. Conclusion: both formulations proposed as endodontic sealer presented effective antimicrobial activity and acceptable flow. The addition of MMT/CHX and MMT/MET particles decreased the conversion and mechanical properties, but further studies are required to clarify the clinical relevance of these properties.

    Palavras-Chave: antimicrobial agents; metronidazole; organic chlorine compounds; dentistry; drugs; sealing materials; montmorillonite; nanoparticles; teeth; seals

  • IPEN-DOC 20351

    VIANA, H.; COSENTINO, I.C. ; GENOVA, L. . A aplicação de cerâmicas mesoporosas com catalisadores de transesterificação para obtenção de biodiesel. In: CONGRESSO BRASILEIRO DE CERAMICA, 58., 18-21 de maio, 2014, Bento Gonçalves, RS. Resumo... 2014. p. 803.

    Palavras-Chave: ceramics; porous materials; biodiesel fuels; catalysts; esterification; nanoparticles

  • IPEN-DOC 27944

    KOMATSU, LUIZ G.H. ; OLIANI, WASHINGTON L. ; LUGAO, ADEMAR B. ; PARRA, DUCLERC F. . Aplicação de ZnO como carregador de prata em uma blenda de HMSPP/SEBS visando ação biocida / Aplication of ZnO as carrier of silver in the blend of HMSPP/SEBS for biocide activity. In: CONGRESSO BRASILEIRO DE POLÍMEROS, 15., 27-31 de outubro, 2019, Bento Gonçalves-RS. Anais... São Carlos, SP: Associação Brasileira de Polímeros, 2019. p. 2356-2359.

    Abstract: Este estudo consiste em utilizar o óxido de zinco (ZnO) como carregador de nanoprata metálica (Ag°). Foi testado um método para síntese das partículas com a prata, o método de Turkevich. A confecção dos filmes poliméricos em matriz de HMSPP/SEBS foi realizada via processamento no estado fundido em extrusora. Os materiais obtidos foram caracterizados pelas técnicas de DLS, MEV e ensaios biocidas. As partículas apresentaram-se em tamanhos variando entre 100 à 200 nm, juntamente a isso, elas também apresentaram resultados de morte celular nos ensaios biocidas com as bactérias E.coli e S.aureus de acordo com a norma JIZ 2801.

    Palavras-Chave: films; polymers; zinc oxides; nanoparticles; silver; disinfectants; bacteria

  • IPEN-DOC 21100

    SOUZA, DAIANE C.B. ; ROSTELATO, MARIA E.C. ; VICENTE, ROBERTO ; ZEITUNI, CARLOS A. ; TIEZZI, RODRIGO ; COSTA, OSVALDO L. ; SOUZA, CARLA D. ; PELEIAS JUNIOR, FERNANDO S. ; RODRIGUES, BRUNA T. ; SOUZA, ANDERSON S. ; KARAM JUNIOR, DIB; BATISTA, TALITA Q.; MELO, EMERSON R.; CAMARGO, ANDERSON R. . Assessment of the risks associated with iodine-125 handling production sources for brachytherapy. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE; MEETING ON NUCLEAR APPLICATIONS, 12th; MEETING ON REACTOR PHYSICS AND THERMAL HYDRAULICS, 19th; MEETING ON NUCLEAR INDUSTRY, 4th, October 4-9, 2015, São Paulo, SP. Proceedings... 2015.

    Palavras-Chave: hydrogels; pvp; nanoparticles; cellulose; silver; polymers; swelling; scanning electron microscopy; toxicity

  • IPEN-DOC 27171

    FONTES, E.H. ; NANDENHA, J. ; SOUZA, R.F.B. de ; ANTONIO, F.C.T.; HOMEM-DE-MELLO, P.; NETO, A.O. . Au core stabilizes CO adsorption onto Pd leading to CO2 production. Materials Today Advances, v. 6, p. 1-9, 2020. DOI: 10.1016/j.mtadv.2020.100070

    Abstract: Au core and Pd shell supported on carbon structure Au@Pd/C can cleave the CeC bond of ethanol molecules leading to the production of a relatively high amount of CO2 when compared with Pd/C electrocatalyst as the attenuated total reflectance - Fourier transform infrared (ATR-FTIR) experiment shows. Density functional theory (DFT) calculations showed that this could be explained by the oxidation of CO species adsorbed into Pd sites that has a modified electronic structure compared with Pd/C. In terms of DFT analysis, the highest thermodynamical stability of CO in Pd shell with Au core atoms, when compared with Pd/C is because of the increase of virtual orbital states near Fermi level that can be occupied by valence electrons of CO molecule. The d-band center shift is experimentally verified using the valence band X-ray photoelectron spectroscopy and theoretically predicted by the Generalized Koopmans’ Theorem. Besides that, Au@Pd/C electrocatalyst has a better electrochemical activity when compared with Pd/C.

    Palavras-Chave: ethanol; oxidation; calculation methods; density; nanoparticles; adsorption; carbon dioxide; density functional method

  • IPEN-DOC 26620

    LEAL, GEORGIA B. ; SILVA, DANIELA C.L. da ; WATACABE, BEATRIZ N. ; CIOTTI, LIGIA ; ANTONIASSI, RODOLFO M. ; GIUDICI, REINALDO; LINARDI, MARCELO ; VAZ, JORGE M. ; SPINACE, ESTEVAM V. . Au/TiO2 catalysts prepared by borohydride reduction for preferential CO oxidation at near-ambient temperature. Catalysis for Sustainable Energy, v. 6, n. 1, p. 6-12, 2019. DOI: 10.1515/cse-2019-0002

    Abstract: Au nanoparticles were prepared in solution using HAuCl4.3H2O as Au precursor, sodium citrate as stabilizing agent and sodium borohydride as reducing agent. The influence of synthesis parameters such as BH4:Au and Citrate:Au ratios were studied. In a further step, the stabilized Au nanoparticles were supported on TiO2 with different Au loadings (wt%). The resulting Au/ TiO2 catalysts were characterized by Energy-dispersive X-ray spectroscopy, X-ray diffraction and Transmission Electron Microscopy and tested for the preferential oxidation of carbon monoxide in hydrogen-rich stream. Au nanoparticles stabilized in solution were obtained with sizes in the range of 3-4 nm. After supported on TiO2, the Au nanoparticles size did not change and the Au/TiO2 catalysts exhibited excellent performance and stability in the temperature range of 20 - 50 °C.

    Palavras-Chave: gold; hydrogen; nanoparticles; carbon monoxide; titanium oxides; borohydrides; reduction; catalysts

  • IPEN-DOC 27899

    ALENCAR, C.S.L. ; PAIVA, A.R.N. ; SILVA, L.G.A. ; SOMESSARI, E.S.R. ; VAZ, J.M. ; SPINACE, E.V. . AuCu/TiO2 catalysts prepared using electron beam irradiation for the preferential oxidation of carbon monoxide in hydrogen-rich mixtures. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-16, 2021. DOI: 10.15392/bjrs.v9i1A.1497

    Abstract: The major part of the world production of hydrogen (H2) is originated from a combination of methane steam reforming and water gas shift reaction resulting in an H2 rich mixture known as reformate gas, which contains about 1% vol (10,000 ppm) of carbon monoxide (CO). The preferential oxidation reaction of CO in H2 rich mixtures (CO PROX) has been considered a very promising process for H2 purification, reducing CO for values below 50 ppm allowing its use in PEMFC Fuel Cells. Au nanoparticles supported on TiO2 (Au/TiO2) catalysts have been shown good activity and selectivity for CO PROX reaction in the temperature range between 20 80 ºC; however, the catalytic activity strongly depends on the preparation method. Also, the addition of Cu to the Au/TiO2 catalyst could increase the activity and selectivity for CO PROX reaction. In this work, AuCu/TiO2 catalysts with composition 0.5%Au0.5%Cu/TiO2 were prepared in a single step using electron beam irradiation, where the Au3+ and Cu2+ ions were dissolved in water/2 propanol solution, the TiO2 support was dispersed and the obtained mixture was irradiated under stirring at room temperature using different dose rates (8 64 kGy s 1) and total doses (144 576 kGy). The catalysts were characterized by energy dispersive X ray analysis, X ray diffraction transmission electron microscopy, temperature programmed reduction and tested for CO PROX reaction. The best result was obtained with a catalyst prepared with a dose rate of 64 kGy s 1 and a total dose of 576 kGy showed a CO conversion of 45% and a CO2 selectivity of 30% at 150 ºC.

    Palavras-Chave: absorbed radiation doses; carbon monoxide; catalysts; copper; dose rates; electron beams; gold; hydrogen; irradiation; mixtures; nanoparticles; oxidation; titanium oxides

  • IPEN-DOC 26284

    ALENCAR, CATARINE S.L. ; PAIVA, ANA R.N. ; SILVA, LEONARDO G. de A. e ; SOMESSARI, ELIZABETH S.R. ; VAZ, JORGE M. ; SPINACE, ESTEVAM V. . AuCu/TiO2 catalysts prepared using electron beam irradiation for the preferential oxidation of carbono monoxide in hydrogen-rich mixtures. In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE, October 21-25, 2019, Santos, SP. Proceedings... Rio de Janeiro: Associação Brasileira de Energia Nuclear, 2019. p. 2481-2491.

    Abstract: The major part of the world production of hydrogen is originated from a combination of methane steam reforming and water gas shift reaction resulting in a n H 2 rich mixture known as reformate gas, which contains about 1% vol (10, 000 p pm) of carbon monoxide (CO). The preferential oxidation reaction of CO in H 2 rich mixtures (CO PROX) has been considered a very promising process for H 2 purification, reducing CO for values below 50 ppm allowing its use in Proton Exchange Membrane Fuel Cells (PEMFC). Au nanopart icles supported on TiO 2 (Au/TiO 2 ) catalysts have been shown good activity and selectivity for CO PROX reaction in the temperature range between 20 ºC and 80 ºC; however, the catalytic activity strongly depend s on the preparation method. Also, the addition of Cu to the Au/TiO 2 catalyst could increase the activity and selectivity for CO PROX reaction. In this work, AuCu/TiO 2 catalysts with composition 0.5%Au0. 5%Cu/TiO 2 were prepared in a single step using electron beam irradiation, where the Au 3+ and Cu 2+ ion s were dissolved in water/2 propanol solution , the TiO 2 support was dispersed and the obtained mixture was irradiated under stirring at room temperature using different dose rates ( 8 64 kGy s 1 ) and doses 144 576 kGy The catalysts were characterized by energy dispersive X ray analysis (EDX), X ray diffraction (XRD), transmissi on electron microscopy (TEM), temperature programmed reduction (TPR) and tested for CO PROX reaction In the studied conditions, it was observed that the increase of t he dose rate and the total dose contributed to a decrease in the mean nanoparticle sizes. The best result was obtained with a catalyst prepared with a dose rate of 64 kGy s 1 and a dose of 576 kGy showed a CO conversion of 45% and a CO 2 selectivity of 30% at 150 o C.

    Palavras-Chave: absorbed radiation doses; carbon monoxide; catalysts; copper; dose rates; electron beams; gold; hydrogen; irradiation; mixtures; nanoparticles; oxidation; titanium oxides; transmission electron microscopy; x-ray diffraction; x-ray spectroscopy

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É possível efetuar a busca de um autor ou um termo em todo o RD, por meio do Buscar no Repositório , isto é, o termo solicitado será localizado em qualquer campo do RD. No entanto esse tipo de pesquisa não é recomendada a não ser que se deseje um resultado amplo e generalizado.

A pesquisa apresentará melhor resultado selecionando um dos filtros disponíveis em Navegar

Os filtros disponíveis em Navegar tais como: Coleções, Ano de publicação, Títulos, Assuntos, Autores, Revista, Tipo de publicação são autoexplicativos. O filtro, Autores IPEN apresenta uma relação com os autores vinculados ao IPEN; o ID Autor IPEN diz respeito ao número único de identificação de cada autor constante no RD e sob o qual estão agrupados todos os seus trabalhos independente das variáveis do seu nome; Tipo de acesso diz respeito à acessibilidade do documento, isto é , sujeito as leis de direitos autorais, ID RT apresenta a relação dos relatórios técnicos, restritos para consulta das comunidades indicadas.

A opção Busca avançada utiliza os conectores da lógica boleana, é o melhor recurso para combinar chaves de busca e obter documentos relevantes à sua pesquisa, utilize os filtros apresentados na caixa de seleção para refinar o resultado de busca. Pode-se adicionar vários filtros a uma mesma busca.

Exemplo:

Buscar os artigos apresentados em um evento internacional de 2015, sobre loss of coolant, do autor Maprelian.

Autor: Maprelian

Título: loss of coolant

Tipo de publicação: Texto completo de evento

Ano de publicação: 2015

Para indexação dos documentos é utilizado o Thesaurus do INIS, especializado na área nuclear e utilizado em todos os países membros da International Atomic Energy Agency – IAEA , por esse motivo, utilize os termos de busca de assunto em inglês; isto não exclui a busca livre por palavras, apenas o resultado pode não ser tão relevante ou pertinente.

95% do RD apresenta o texto completo do documento com livre acesso, para aqueles que apresentam o significa que e o documento está sujeito as leis de direitos autorais, solicita-se nesses casos contatar a Biblioteca do IPEN, bibl@ipen.br .

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

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

Na página inicial nas referências são sinalizados todos os autores IPEN, ao clicar nesse símbolo será aberta uma nova página correspondente à aquele autor – trata-se da página do pesquisador.

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

ATENÇÃO!

ESTE TEXTO "AJUDA" ESTÁ SUJEITO A ATUALIZAÇÕES CONSTANTES, A MEDIDA QUE NOVAS FUNCIONALIDADES E RECURSOS DE BUSCA FOREM SENDO DESENVOLVIDOS PELAS EQUIPES DA BIBLIOTECA E DA INFORMÁTICA.

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

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

1. Portaria IPEN-CNEN/SP nº 387, que estabeleceu os princípios que nortearam a criação do RDI, clique aqui.


2. A experiência do Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) na criação de um Repositório Digital Institucional – RDI, clique aqui.

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

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

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

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