Navegação por Autores IPEN "OTUBO, LARISSA"

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  • IPEN-DOC 30030

    OLIVEIRA, VINICIUS L.T. de ; SANTOS, LUAN J. dos ; ROCHA, CLAUDIO J. da ; FELGUEIRAS, CARLOS F. ; OTUBO, LARISSA ; MATSUDA, MARGARETH M.N. . Estudo preliminar de validação de filtração esterilizante: microscopia em filtros de GUAN-IPEN-123. In: CONGRESSO BRASILEIRO DE MEDICINA NUCLEAR, 37., 21-23 de setembro, 2023, Porto de Galinhas, PE. Resumo... São Paulo, SP: Sociedade Brasileira de Medicina Nuclear - SBMN, 2023.

    Abstract: OBJETIVO - O processo de filtração esterilizante deve ser validado para comprovar que a esterilização do produto é efetiva nas condições reais de processo e que o filtro não causa alterações prejudiciais na composição do produto e que o produto não altera a eficiência do filtro. Quando um produto não pode ser esterilizado no recipiente final, as soluções devem ser filtradas através de um filtro estéril de tamanho de poro nominal de 0,22 micrômetros ou menor. Na validação da filtração esterilizante devem ser realizados os seguintes testes: compatibilidade entre o filtro e o produto, verificação da adsorção de componentes do produto e substâncias extraíveis, e o desafio microbiológico com 1x107 unidades formadoras de colônia (UFC) de Brevundimonas diminuta por cm2 de superfície do filtro. A filtração esterilizante é o método de escolha para esterilização de radiofármacos como é ocaso de GUAN-IPEN-123 iobenguano (123 I). O objetivo deste trabalho é realizar estudo preliminar por microscopia eletrônica de varredura do filtro esterilizante após filtração do radiofármaco GUAN-IPEN-123 e do microrganismo Pseudomonas aeruginosa. MATÉRIAIS E MÉTODOS – Utilizou-se microscópio eletrônico de varredura (SEM-FEG) marca Jeol modeloJSM-6701F, membrana de filtração Millipore Millex-GV (fluoreto de polivinilideno) 0,22 μm, microrganismo BioMerieux Bioball Pseudomonas aeruginosa NCTC 12924. Foram obtidas microscopias da membrana, após filtração de GUAN-IPEN-123 e após passagem de 5 mL de Pseudomonas aeruginosa de cerca de 4,5x108 UFC. Os filtros foram submetidos a decaimento do I-123 e as membranas foram secas e o microrganismo foi fixado com etanol PA para obtenção das microscopias após recobrimento com carbono. RESULTADOS – A microscopia da membrana antes da filtração de GUAN-IPEN-123 mostrou integridade da superfície e a dimensão do poro conforme, sendo adequado para uso em filtração esterilizante. Após a filtração, foi observada deposição de material sobre a membrana. A presença de Pseudomonas aeruginosa (tamanho entre 0,5 μm a 0,8 μm) sobre a superfície da membrana indicou retenção do microrganismo de tamanho similar a Brevundimonas diminuta utilizada na validação de filtração esterilizante. CONCLUSÃO – As microscopias por SEM-FEG e a utilização do microrganismo Pseudomonas aeruginosa mostraram-se adequadas na análise preliminar das membranas utilizadas na filtração esterilizante do radiofármaco GUAN-IPEN-123.

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  • IPEN-DOC 28132

    SOUZA, RODRIGO F.B. de ; MAIA, VICTORIA A. ; ZAMBIAZZI, PRISCILLA J. ; OTUBO, LARISSA ; LAZAR, DOLORES R.R. ; NETO, ALMIR O. . Facile, clean and rapid exfoliation of boron-nitride using a non-thermal plasma process. Materials Today Advances, v. 12, p. 1-5, 2021. DOI: 10.1016/j.mtadv.2021.100181

    Abstract: Non-Thermal Plasma source was used in this work to exfoliated boron-nitride (BN) powders. The generation of hexagonal BN nanosheets (h-BNNSs) few-layered was observed by TEM. The hBN exfoliation occurred along their transverse axis, preserving the hexagonal structure. The micrographs showed ordered lattice fringes with d-spacing of approximately 0.33 nm indicating the increase of (0 0 2) h-BNNSs crystal lattice planes, also confirmed by the relative peak intensity decrease in relation to the other peaks in XRD measures. The few amounts of layers were confirmed by intensity decrease, enlargement, and blue shift of E2 g vibrational mode in Raman spectra. Moreover, the appearance of the FTIR band corresponding to the hydroxyl group occurs due to large amounts of defects such as vacancy defects.

    Palavras-Chave: boron nitrides; plasma heating; function generators; two-dimensional systems

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  • IPEN-DOC 28429

    CATANHEIRA, BRUNA; OTUBO, LARISSA ; OLIVEIRA, CRISTIANO L.P.; MONTES, ROSA; QUINTANA, JOSE B.; RODIL, ROSARIO; BROCHSZTAIN, SERGIO; VILAR, VITOR J.P.; TEIXEIRA, ANTONIO C.S.C.. Functionalized mesoporous silicas SBA-15 for heterogeneous photocatalysis towards CECs removal from secondary urban wastewater. Chemosphere, v. 287, Part 1, p. 1-11, 2022. DOI: 10.1016/j.chemosphere.2021.132023

    Abstract: The photocatalytic activity of TiO2 nanoparticles (NPs) supported on mesoporous silica SBA-15 (TiO2/SBA-15) was evaluated for the photodegradation of sulfadiazine (SDZ), as target contaminant of emerging concern (CEC), using either pure water solutions (PW) or a real secondary urban wastewater (UWW) spiked with SDZ. For this purpose, TiO2/SBA-15 samples with 10, 20 and 30% TiO2 (w/w) were prepared by the sol-gel post synthetic method on pre-formed SBA-15, using titanium (IV) isopropoxide as a precursor. The TiO2/SBA-15 materials were characterized by HRTEM, SAXS and XRD, nitrogen adsorption isotherms and UV–vis diffuse reflectance spectroscopy. TiO2 NPs were shown to be attached onto the external surface, decorating the SBA-15 particles. The TiO2/SBA-15 catalysts were active in SDZ photodegradation using the annular FluHelik photoreactor, when irradiated with UVA light. The 30% TiO2/SBA-15 sample presented the best performance in optimization tests performed using PW, and it was further used for the tests with UWW. The photocatalytic activity of 30% TiO2/SBA-15 was higher (56% SDZ degradation) than that of standard TiO2–P25 (32% SDZ degradation) in the removal of SDZ spiked in the UWW ([SDZ] = 2 mg L−1). The photodegradation of SDZ with 30% TiO2/SBA-15 eached 90% for UWW spiked with a lower SDZ concentration ([SDZ] = 40 μg L−1). Aside of SDZ, a suit of 65 other CECs were also identified in the UWW sample using LC-MS spectrometry. A fast-screening test showed the heterogeneous photocatalytic system was able to remove most of the detected CECs from UWW, by either adsorption and/or photocatalysis.

    Palavras-Chave: oxidation; photocatalysis; silica; porous materials; sulfonamides

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  • IPEN-DOC 27825

    NAGAI, MARIA L.E. ; SANTOS, PAULO de S. ; OTUBO, LARISSA ; OLIVEIRA, MARIA J.A. ; VASQUEZ, PABLO A.S. . Gamma and electron beam irradiation effects for conservation treatment of cellulose triacetate photographic and cinematographic films. Radiation Physics and Chemistry, v. 182, p. 1-10, 2021. DOI: 10.1016/j.radphyschem.2021.109395

    Abstract: Photographic and cinematographic films of cellulose triacetate safeguarded in historical and cultural institutions are often contaminated by fungi when stored in inadequate conditions of humidity and temperature. The presence of fungi affects the image contained in the films, accelerates the process of biodeterioration and represents a risk to the health of people working with contaminated materials. In addition, another common physicochemical degradation affecting cellulose triacetate films causing deacetylation of polymer chain is called “vinegar syndrome”. Considering the dose interval established for the disinfection of cultural heritage materials, in this work the effects of irradiation with gamma rays and electron beam on photographic and cinematographic films of cellulose triacetate were evaluated. Additionally, the thermal stability behavior of the films and the feasibility of crosslinking of CTA films were investigated. Film samples were selected and characterized by FTIR-ATR spectroscopy. Irradiated samples by gamma rays and electron beam with radiation absorbed doses between 6 kGy and 200 kGy were examined by FEGSEM microscopy, UV–Vis spectrophotometry and differential scanning calorimetry (DSC). The results showed that disinfection by gamma and electron beam irradiation, in the dose range of 6 kGy–10 kGy, does not change or modification of main properties of the constitutive materials of photographic and cinematographic films. The applied dose of 50 kGy, both gamma rays and electron beam, indicated a crosslinking effect on the films and can be considered a possibility for the treatment of films affected by the “vinegar syndrome”.

    Palavras-Chave: photographic films; cinematography; cultural resources; electron beams; gamma radiation

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  • IPEN-DOC 29865

    GOMES, PAULO V.R. ; BONIFACIO, RAFAEL N. ; SILVA, BARBARA P.G. ; FERREIRA, JOAO C. ; SOUZA, RODRIGO F.B. de ; OTUBO, LARISSA ; LAZAR, DOLORES R.R. ; NETO, ALMIR O. . Graphene deposited on glass fiber using a non-thermal plasma system. Eng, v. 4, n. 3, p. 2100–2109, 2023. DOI: 10.3390/eng4030119

    Abstract: This study reports a bottom-up approach for the conversion of cyclohexane into graphene nanoflakes, which were then deposited onto fiberglass using a non-thermal generator. The composite was characterized using transmission electron microscopy, which revealed the formation of stacked few-layer graphene with a partially disordered structure and a d-spacing of 0.358 nm between the layers. X-ray diffraction confirmed the observations from the TEM images. SEM images showed the agglomeration of carbonaceous material onto the fiberglass, which experienced some delamination due to the synthesis method. Raman spectroscopy indicated that the obtained graphene exhibited a predominance of defects in its structure. Additionally, atomic force microscopy (AFM) analyses revealed the formation of graphene layers with varying levels of porosity.

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  • IPEN-DOC 26873

    SANTOS, DOUGLAS C.; GOES, JOÃO M.R.; SOUZA, VIVIANE C. de; BISPO, DIEGO F.; OTUBO, LARISSA ; ANDRADE, GEORGE R.S.; CAMARGO, ZAINE T.; SANTOS, EULER A. dos. Green synthesis of silver nanostructures with amino acid-modified Pluronic F127 for antibacterial applications. Applied Surface Science, v. 505, p. 1-12, 2020. DOI: 10.1016/j.apsusc.2019.144449

    Abstract: The aim of this work was to evaluate the use of amino acid-functionalized Pluronic F127 derivatives in the synthesis of silver nanostructures (SNS), such as nanoparticles (SNP) and nanoclusters (SNC). Herein, glycine, Lalanine, and DL-alanine were used to functionalize poly(ethylene oxide) (PEO) end groups from the polymer chain via an esterification pathway. The esterified polymers were used for reducing and stabilizing SNS by a hydrothermal or a photo-assisted route (using a UVA light). The functionalized polymers were characterized by FTIR and the obtained SNS were characterized by UV–vis spectroscopy and TEM, which showed that the SNS obtained by the hydrothermal route are predominantly spherical, whereas those obtained by photo-assisted method give rise to rods and prisms. Kinetic studies showed that alanine and glycine form particles with different rates and that the different enantiomers (L and DL) influence the size and shape of SNS. The nanoparticles obtained by the two routes had their antibacterial efficiency tested against S. aureus by the Agar well diffusion method.

    Palavras-Chave: nanoparticles; silver; nanostructures; pluronics; synthesis; antibiotics; amino acids; alanines; reduction; photochemistry

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  • IPEN-DOC 26664

    CAMPOS, ALEX C.; PAES, SUANE C.; CORREA, BRUNO S.; CABRERA-PASCA, GABRIEL A.; COSTA, MESSIAS S.; COSTA, CLEIDILANE S.; OTUBO, LARISSA ; CARBONARI, A.W. . Growth of long ZnO nanowires with high density on the ZnO surface for gas sensors. ACS Applied Nano Materials, v. 3, n. 1, p. 175-185, 2020. DOI: 10.1021/acsanm.9b01888

    Abstract: Among the various approaches to grow semiconducting oxide nanowires, the thermal oxidation procedure is considered a simple, efficient, and fast method that allows the synthesis of micro and nanostructured arrangements with controlled size and morphology. In the work reported in this paper, long ZnO nanowires were synthesized on the surface of oxidized high-purity Zn foils by heating in air at different rates and temperatures. The size and morphology investigated by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) for a sample heated at 620 °C with heating rate of 20 °C/min reveal the growth of long ZnO nanowires with length of ∼50 μm and average diameter of 74 nm grown along the ⟨112̅0⟩ direction with high population density. Results with different heating rates indicates that this parameter is determinant in tuning the size, morphology, and population density of nanowires. X-ray diffraction (XRD) shows patterns for both ZnO and metallic Zn with preferential orientation, whereas perturbed angular correlation (PAC) measurements using 111In(111Cd) probe nuclei indicate that probe nuclei occupy only Zn sites in the preferential oriented metallic zinc. However, for samples submitted to high-temperature heating (820 and 1000 °C), XRD yields only the ZnO pattern and, amazingly, PAC continues showing probe nuclei only at metallic Zn sites indicating the presence of thin regions of highly oriented Zn trapped between grains of ZnO. Moreover, this strong preference of indium atoms (of parent radioactive 111In) here revealed helps to understand the oxidation mechanism and the growth of the nanowires.

    Palavras-Chave: zinc oxides; nanowires; electric fields; oxidation; temperature gradients; x-ray diffraction; thermal analysis; transmission electron microscopy

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  • IPEN-DOC 22647

    GUEDES-SILVA, C.C. ; FERREIRA, THIAGO dos S. ; CARVALHO, FLAVIO, M.S.; PAULA, CAROLINA M. de ; OTUBO, LARISSA . Influence of alumina phases on the molybdenum adsorption capacity and chemical stability for 99Mo/99mTc generators columns. Materials Research, v. 19, n. 4, p. 791-794, 2016. DOI: 10.1590/1980-5373-MR-2015-0560

    Abstract: Technetium-99m is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate 99Mo and 99mTc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al2O3 phases as well as specific surface area between 36 and 312 m2 g-1. Most interesting results were reached by powders calcined at 900oC for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina.

    Palavras-Chave: aluminium oxides; molybdenum; adsorption; molybdenum 99; technetium; chemical composition; stability

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  • IPEN-DOC 22560

    SOUZA, LANARCK C.M.; SANTOS, THIAGO A.; PRADO, CASSIO R.A. do; LIMA, BENEDICTO A.V.; CORREA, RODRIGO S.; BATISTA, ALZIR A.; OTUBO, LARISSA ; ELLENA, JAVIER; UENO, LEONARDO T.; DINELLI, LUIS R.; BOGADO, ANDRE L.. Influence of gold nanoparticles applied to catalytic hydrogenation of acetophenone with cationic complexes containing ruthenium. RSC Advances, v. 6, p. 53130-53139, 2016.

    Palavras-Chave: x-ray diffraction; gold; nanoparticles; hydrogenation; acetophenone; complexes; ruthenium; ruthenium complexes; synthesis

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  • IPEN-DOC 26551

    NAGAI, MARIA L.E.; SANTOS, PAULO S. ; OTUBO, LARISSA ; OLIVEIRA, MARIA J.A. de ; VASQUEZ, PABLO A.S. . Ionizing radiation for the preservation and conservation of photographic and cinematographic films. In: VASQUEZ, PABLO A.S. (Ed.); NAGAI, MARIA L.E. (Coord.) INTERNATIONAL SYMPOSIUM ON GAMMA IONIZATION: TECHNOLOGY FOR PRESERVATION OF CULTURAL HERITAGE, 1st, October 25, 2019, São Paulo, SP. Abstract... São Paulo, 2019.

    Abstract: The Nuclear and Energy research Institute – IPEN-CNEN/SP through the Multipurpose Gamma Irradiation Facility has treated several bibliographical collections of Sao Paulo University-USP for disinfestation and disinfection of contaminated materials with insects and fungi. In this sense, gamma radiation from cobalt-60 is an excellent alternative tool to the traditional preservation process mainly because the biocidal action. Disinfection using gamma radiation for cultural heritage materials has been widely applied around the world in the last decades. Adequate storage of photographic and cinematographic materials is a challenge for conservation experts from preservation institutions. Contamination by fungi is one of leading causes of problem in this kind of collections. In addition, another common physicochemical degradation affecting cellulose triacetate films causing deacetylation of polymer chain is called “vinegar syndrome”. In this work are presented results of effect of ionizing radiation on photographic and cinematographic films. Selected films were characterized by FTIR-ATR spectroscopy and FEGSEM-EDS microscopy. Samples were irradiated by gamma rays with absorbed dose between 2 kGy and 200 kGy. Irradiated samples were analyzed by UV-vis spectrophotometry, FEGSEM, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Results showed that disinfection by gamma rays can be achieved safely applying radiation absorbed doses between 6 kGy and 10 kGy with no change or modification of main properties of the constitutive polymeric materials. Gamma rays due to the effect of crosslinking is presented as an alternative to treat films affected by “vinegar syndrome” applying absorbed dose of 50 kGy in order to increase shelf life of cultural heritage materials.

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  • IPEN-DOC 26553

    KODAMA, YASKO ; RODRIGUES JUNIOR, ORLANDO ; GARCIA, RAFAEL H.L. ; OTUBO, LARISSA ; SANTOS, PAULO S. ; VASQUEZ, PABLO A.S. . Kinetics of Free Radicals Decay Reactions in Cellulosic Based Heritage Materials Disinfected by Gamma Radiation. In: VASQUEZ, PABLO A.S. (Ed.); NAGAI, MARIA L.E. (Coord.) INTERNATIONAL SYMPOSIUM ON GAMMA IONIZATION: TECHNOLOGY FOR PRESERVATION OF CULTURAL HERITAGE, 1st, October 25, 2019, São Paulo, SP. Abstract... São Paulo, 2019.

    Abstract: In this study, contemporary paper samples were irradiated using gamma radiation from Co-60 with different absorbed doses. The absorbed dose range was chosen taking into account the effective values to promote insect eradication, fungal disinfection and sterilization. The kinetics of decay of the cellulose free radicals induced by irradiation was analyzed using Electron Paramagnetic Resonance. Several spectra were obtained at room temperature for each applied absorbed dose immediately after irradiation as reference measurements. In order to understand the decay process of free radicals, additional spectra were obtained for different decay times up to almost 50 days after irradiation. De-noising treatment of the original obtained spectra signals were performed using wavelets. By integrating the electron paramagnetic resonance curves were calculated the area values and correlated to concentration, it is equivalent to spin concentration. Comparison of spectra was done by normalization of calculated area corresponding to cellulose spin concentration, considering the first measurement after irradiation as 100%. Further analyses and calculations were made to study the half-life and the kinetics models of the free radicals created. X-ray diffraction was carried out to identify crystalline phases and the effect of ionizing radiation on the crystalline structure of cellulose in paper. Scanning electron microscopy and Scanning Electron Microscopy Energy Dispersive Spectrometry were performed to analyze structure modifications by ionizing radiation, identifying cellulose fiber agglomeration zones and to quantify chemical elements. Likewise, samples were analyzed by infrared spectroscopy to determinate changes on the carbonyl groups. Results shown that for sterilization dose, 80% of the cellulose free radicals induced by ionizing radiation disappear in almost 40 days and for disinfection dose in 8 days. It can be concluded that if no significant modifications (side-effects) appear in the irradiated material after the radical decay time, the material will stay stable for the remaining lifetime. Proposed method using electron paramagnetic resonance results showed suitably to study the behavior of radicals on cellulosic based cultural heritage materials.

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  • IPEN-DOC 28561

    TRINDADE, FABIANE J.; DAMASCENO, SERGIO; OTUBO, LARISSA ; SCHMAL, MARTIN; FLORIO, DANIEL Z. de; FONSECA, FABIO C. ; FERLAUTO, ANDRE S.. Lanthanum doped ceria shaped nanostructures for oxidative coupling of methane. In: BRAZIL MRS MEETING, 19th; INTERNATIONAL UNION OF MATERIALS RESEARCH SOCIETIES - INTERNATIONAL CONFERENCE ON ELECTRONIC MATERIALS, August 30 - September 3, 2021, Online. Abstract... São Carlos, SP: Aptor Software, 2021. p. 308-308.

    Abstract: The abundance of natural gas due to the advancements in exploration and extraction technologies has increased the interest in the direct conversion of methane to C2 molecules via oxidative coupling of methane (OCM) reactions [1]. The design of catalysts by tailoring shape and oxygen vacancies has a significant impact on their performance [2]. Within this context, in this work, the fine-tuning of structural defects of ceria rod-like and cube-like shaped nanoparticles were performed via La3+ doping (LaxCe1-xO2-x/2) in molar ratios of x=5-90 mol %. The morphology control was achieved by varying the hydrothermal synthesis temperature from 110 °C to 180 °C. The characterization of LaxCe1-xO2-1/2 catalysts was performed by SEM, HRTEM, XRD, and Raman spectroscopy. The catalytic performance of the new nanomaterials for the OCM reaction was studied at 750 °C with an in-line gas chromatograph. In the LaxCe1-xO2-x/2 nanorods, the fluorite crystalline structure is essentially maintained even for x = 0.6. The Raman spectra analysis indicates that the addition of La3+ leads and increases the formation of different amounts of extrinsic and intrinsic oxygen vacancies. In addition, the catalytic tests for OCM reaction show that the LaxCe1- xO2-1/2 (x=50%) nanorods catalyst have 25% of CH4 conversion and 48% of selectivity for C2 products. The concentration of reactive oxygen species in the LaxCe1-xO2-1/2 (x=50%) nanorods was crucial to improving the conversion rates and selectivity.

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  • IPEN-DOC 28999

    GOMES, PAULO V.R. ; AZEREDO, NATHALIA F.B. ; GARCIA, LUIS M.S. ; ZAMBIAZI, PRISCILLA J. ; MORSELLI, GIOVANNI R.; ANDO, ROMULO A.; OTUBO, LARISSA ; LAZAR, DOLORES R.R. ; SOUZA, RODRIGO F.B. de ; RODRIGUES, DEBORA F.; NETO, ALMIR O. . Layered graphene/hexagonal boron nitride nanosheets (Gr/h-BNNs) applied to the CO2 photoconversion into methanol. Applied Materials Today, v. 29, p. 1-8, 2022. DOI: 10.1016/j.apmt.2022.101605

    Abstract: Photocatalysts based on heterostructure 2D materials show promising properties for the construction of optoelectronic devices for selective reduction of CO2 to methanol. In this sense, a fast and simple method to produce 2D hexagonal hybrid BN nanosheets (h-BNNs) doped with graphene heterostructure by van der Waals interactions was developed. The method used plasma created by a Tesla coil. The Gr/h-BNNs hybrid material obtained presented a stacking structure containing h-BNNs and graphene layers. The structure included doping of carbon atoms along the h-BN edge structures. The doping of the h-BN nanostructure with graphene sheets, conferred adaptable optical properties to the semiconductor, resulting in band gap energy values favorable to photocatalysis. The reaction promoted selective reduction of CO2 to methanol, and synthesis of other products, such as formaldehyde and formic acid, due to multielectronic transfer processes.

    Palavras-Chave: plasma; boron nitrides; doped materials; graphene; nanofilms

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  • IPEN-DOC 25555

    SOARES JUNIOR, FRANCISCO H.; VIEIRA, LAIS H. e S.; OTUBO, LARISSA ; SOARES, JOAO M.; FERREIRA, ODAIR P.. Magnetic hydrochar prepared from sugarcane bagasse. In: BRAZILIAN MEETING ON INORGANIC CHEMISTRY, 19th; LATIN AMERICAN MEETING ON BIOLOGICAL INORGANIC CHEMISTRY, 6th; BRAZILIAN MEETING ON RARE EARTHS, 8th, September 24-28, 2018, Fortaleza, CE. Abstract... 2018.

    Abstract: Magnetic hydrochar is known for its technological applications such as environmental remediation, biosensors, adsorption, drug delivery and catalysis [1]. However, magnetic iron oxide can be easily oxidized, causing reduction of magnetic properties. Because of these limitations, such materials could be improved for greater stability. Hydrothermal carbonization at moderate temperatures (150-350°C) has been recognized as a auspicious and efficient methodology for preparing carbonaceous material from biomass residues [2, 3]. In this work, we performed the preparation and characterization of magnetic hydrochar via one-pot hydrothermal carbonization of biomass. The samples were prepared by treating hydrothermally sugarcane bagasse in presence of iron nitrate (III). Reaction parameters such as temperature, time and mass proportion of iron nitrate to bagasse were studied. Structural characterization revealed a mixture of iron oxide phases: hematite and maghemite. SEM and TEM images showed spherical particles with mean diameter between 1-5 μm and irregular clusters of nanostructures with diameters ranging from 5-11 nm, respectively. On the surface were detected oxygen groups (hidroxila, fenólica, carbonila ou carboxílica). The specific surface area was measured to be 71.54-162.63 m2/g and it’s saturation magnetization 13.1-34.3 emu/g. The results suggest that the samples were composed of carbon microparticles and iron oxide nanoparticles. The carbon layers were observed to be encapsulating the iron oxide nanoparticles, in which the magnetite phase is responsible for the magnetic response.

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  • IPEN-DOC 28823

    ARAUJO, GUILHERME R.S. de; MACIEIRA, GIVALDA M. da C.; OLIVEIRA, DAYANE X. de; MATOS, SAULO S.; SANTOS, QUESIA N. dos; OTUBO, LARISSA ; ARAUJO, ADRIANO A. de S.; DUARTE, MARCELO C.; LIRA, ANA A.M.; NUNES, ROGERIA de S.; SARMENTO, VICTOR H.V.. Microemulsions formed by PPG-5-CETETH-20 at low concentrations for transdermal delivery of nifedipine: structural and in vitro study. Colloids and Surfaces B: Biointerfaces, v. 214, p. 1-9, 2022. DOI: 10.1016/j.colsurfb.2022.112474

    Abstract: Nifedipine is a potent anti-hypertensive, which is poorly orally bioavailable on account of first-pass metabolism, short half-life, and low water solubility. This study aimed to develop a microemulsified system with low surfactant concentration and to evaluate the influence of microemulsion (ME) phase behavior on skin permeation of nifedipine, as drug model. Thereafter, MEs were obtained using PPG-5-CETETH-20, oleic acid, and phosphate buffer at pH 5.0. The selected MEs were isotropic, with droplet diameters less than 10 nm, polydispersity index < 0.25, and pH between 5.0 and 5.2. MEs presented low viscosity and Newtonian behavior. SAXS results confirmed bicontinuous and oil-in-water (o/w) MEs formation. The presence of the drug promoted only very slight modifications in the ME structure. The MEs presented ability to deliver nifedipine via the transdermal route when in comparison with the control. Nevertheless, the skin permeated and retained amounts from the o/w and bicontinuous formulations did not differ significantly. The ATR-FTIR demonstrated that both formulations promoted fluidization and disorganization of lipids and increased the drug diffusion and partition coefficients in the skin. In conclusion, PPG-5-CETETH-20 MEs obtained proved to be effective skin permeation enhancers, acting by rising the coefficients of partition and diffusion of the nifedipine in the skin.

    Palavras-Chave: emulsions; nanotechnology; surfactants; drug delivery

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  • IPEN-DOC 20868

    FERREIRA, VANESSA F.; PRADO, CASSIO R.A. do; RODRIGUES, CAROLINA M.; OTUBO, LARISSA ; BATISTA, ALZIR A.; CRUZ JUNIOR, JOSE W. da; ELLENA, JAVIER; DINELLI, LUIS R.; BOGADO, ANDRE L.. Modified glassy carbon electrode with AuNPs using cis-[RuCl(dppb)(bipy)(4-vpy)]sup(+) as crossed linking agent. Polyhedron, v. 78, p. 46-53, 2014.

    Palavras-Chave: gold; nanoparticles; ruthenium complexes; electrodes; carbon

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  • IPEN-DOC 29632

    SOUZA, VIVIANE C. de; RAMOS, GABRIEL dos S.; LEITE, JULIANA L.; SANTOS, MAURICIO B. dos; OTUBO, LARISSA ; CAMARGO, ZAINE T.; VICTOR, MAURICIO M.. A new thioglycolic ester β-cyclodextrin/PdCl2 in water: an accessible catalyst for the Suzuki-Miyaura coupling reaction. Carbohydrate Polymers, v. 301, n. Part A, p. 1-10, 2023. DOI: 10.1016/j.carbpol.2022.120271

    Abstract: A novel, easily prepared and accessible water-soluble supramolecular catalyst for the Suzuki-Miyaura Csingle bondC coupling reaction was synthesized and characterized by FTIR, NMR, XRD, SEM, and HR-TEM. An inexpensive Pd(II) source added to the resulting aqueous solution of thioglycolic ester β-cyclodextrin (1-TGA-SH-β-CD/PdCl2) showed Pd nanoclusters and efficient catalytic activity for Suzuki-Miyaura Csingle bondC coupling reactions of aryl halides with aryl boronic acids, employing K2CO3 as base, in an environmentally benign aqueous solution prepared in open flasks. Organic aryl halides including chlorides can produce moderate to excellent yields with aryl boronic acids and a small catalytic amount (0.01 mol%) of 1-TGA-SH-β-CD/PdCl2. This hydro-soluble catalyst stock solution was stable for long periods (more than three months) and could be reused in two runs until showing loss of catalytic activity. Some experiments to understand the mechanism were performed, with the results suggesting incorporation of aryl halide in the catalytic cavity.

    Palavras-Chave: thiols; dextrin; catalysts; palladium complexes; halides; aqueous solutions; aqueous solutions

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  • IPEN-DOC 27735

    ANDRADE, LUANA dos S.; OTUBO, LARISSA ; CASTANHEIRA, BRUNA; BROCHSZTAIN, SERGIO. Novel periodic mesoporous organosilicas containing pyromellitimides and their application for the photodegradation of asphaltenes. Microporous and Mesoporous Materials, v. 312, p. 1-8, 2021. DOI: 10.1016/j.micromeso.2020.110740

    Abstract: Periodic mesoporous organosilicas containing pyromellitic diimide units embedded in the pore walls (PMOPMI) were synthesized by co-condensation of the bridged silsesquioxane precursor N,N′-bis(3-triethoxysilylpropyl)pyromellitimide with tetraethoxysilane (TEOS) in acidic conditions, in the presence of the structure-directing agent Pluronics P-123. PMOPMI were also synthesized from the corresponding amic acid precursors. The PMOPMI were studied by different techniques, including N2 adsorption isotherms, transmission electron microscopy, infrared and diffuse reflectance spectroscopy and contact angles. The studied samples displayed well-organized 2D-hexagonal structures. The PMOPMI were able to adsorb petroleum asphaltenes from toluene solutions, and were efficient photosensitizers for the photodegradation of the adsorbed asphaltenes when irradiated. Most of the asphaltenes were removed from solutions by the combined action of adsorption and photodegradation processes.

    Palavras-Chave: porous materials; silica; nanocomposites; asphaltenes; photocatalysis; petroleum; ultraviolet radiation

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  • IPEN-DOC 26481

    ARAUJO, JESUINA C.S.; OTON, LAIS F.; OLIVEIRA, ALCINEIA C.; LANG, ROSSANO; OTUBO, LARISSA ; BUENO, JOSE M.C.. On the role of size controlled Pt particles in nanostructured Pt-containing Al2O3 catalysts for partial oxidation of methane. International Journal of Hydrogen Energy, v. 44, n. 50, p. 27329-27342, 2019. DOI: 10.1016/j.ijhydene.2019.08.176

    Abstract: The effect of the Pt loadings and particles sizes on the stability of Pt(x wt%)/Al2O3 catalysts were investigated in the partial oxidation of methane (POM) reaction. The Al2O3 support was prepared by sol-gel method and different Pt loadings, varying from 0.5 to 2.0 wt% were incorporated to alumina through the incipient wetness impregnation method. The physicochemical features of the catalysts were determined by XRD, ICP-OES, Nitrogen-sorption, UVeVisible, H2-TPR, CO-DRIFTS, SEM-EDS, XPS and HRTEM techniques. The metal dispersion was evaluated in the cyclohexane dehydrogenation reaction. Lower Pt loadings resulted in well dispersed Pto nanoparticles with an enhanced activity in cyclohexane dehydrogenation and POM reactions. With increasing Pt loading to 2.0 wt%, the Pt nanoparticles of the Pt(2.0 wt%)/Al2O3 showed a methane conversion of 63% in 24 h of time on stream, and the catalyst was very selective to H2 and CO. Based on the HRTEM, XPS and Raman spectroscopy techniques, an increment in the Pt loadings evidenced an enrichment of Pto clusters on the surface, however, no heavy carbon deposits formation was observed.

    Palavras-Chave: methane; oxidation; aluminium oxides; platinum; nanostructures; catalysts; carbon

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  • IPEN-DOC 20689

    LANG, ROSSANO; OTUBO, LARISSA ; REBOH, SHAY; AMARAL, LIVIO. Optical-structural correlation of FeSisub(2) nanoparticles produced by ion-beam-induced epitaxial crystallization in Fesup(+) implanted SiO2/Si followed by thermal annealing. In: ENCONTRO DA SBPMat - SOCIEDADE BRASILEIRA DE PESQUISA EM MATERIAIS, 13., 28 de setembro - 2 de outubro, 2014, João Pessoa, PB. Resumo... 2014.

    Palavras-Chave: iron silicides; nanostructures; particles; ion beams; crystallization; epitaxy; silicon oxides; annealing

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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.

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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.