24 results on '"João Paulo de Campos da Costa"'
Search Results
2. Optical Filters for Narrow Band Light Adaptation on Imaging Devices
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João Paulo de Campos da Costa, Talita Conte Granado, João Paulo Carmo, and Rodrigo Henrique Gounella
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Materials science ,business.industry ,FILMES FINOS ,Spectral bands ,Atomic and Molecular Physics, and Optics ,law.invention ,Wavelength ,Full width at half maximum ,law ,Transmittance ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Optical filter ,Refractive index ,Light-emitting diode ,Diode - Abstract
The imagiology using Narrow Band Light (NBL) is widely employed in detection of mucosa's premature changes of gastrointestinal tract, while taking advantage of light spectral features by enhancing the vascular structures without the application of any type of dye. NBL uses two specific spectral bands centered in blue (415 nm) and green (540 nm). Despite their greater advantages, this technique is not available on intra-corporal imagiology devices yet. Thus, this paper presents a low-cost method to adapt such devices without the need to develop specific and expensive LEDs (Light-Emitting Diodes) centered at 415 nm and 540 nm. The method combines optical filters with commercial LEDs to provide transmitted light with the desired peaks at 415 nm and 540 nm. Two optical filters were designed and fabricated, using 7 thin-films layers of SiO2 and TiO2 deposited by RF sputtering. The measurements showed that the transmitted light through the filters presented relative transmittance peaks located at 414 nm and 542 nm wavelengths with relative transmittances of 31% and 62% and FWHM (Full-Width-Half-Maximum) of 17 nm and 29 nm, respectively. The measurements also showed significant relative transmittances located at NBL central wavelengths of 415 and 540 nm with 30% and 60%.
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- 2021
3. A scalable electron beam irradiation platform applied for allotropic carbon transformation
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Marcelo Assis, Vinícius Teodoro, Jefferson Bettini, João Paulo de Campos da Costa, Juan Andrés, Elson Longo, and João Paulo Carmo
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Electron beam ,Solid-state chemistry ,Materials science ,solid-state materials ,Pellets ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Anode ,Nanomaterials ,chemistry ,Sputtering ,General Materials Science ,Graphite ,0210 nano-technology ,High-resolution transmission electron microscopy ,allotropic carbon ,Carbon - Abstract
The design of solid-state materials whose properties and functions can be manipulated in a controlled manner by the application of electron beam irradiation is important in modern materials chemistry and physics. In this paper, we present a progress in the development of scalable electron beam irradiation platform to obtain innovative materials for technological and industrial applications, since one of the problems to be solved in this research area is the scalability of these new nanomaterials induced by electron beam irradiation (EBI). In particular, we focus on carbon structures due to its excellent and exciting properties applied in the technological area in the last years, where we show for the first time a new strategy for carbon allotropic transformation through the portable EBI. This new platform is particularly effective, fast, versatile, clean and easy-to-use, facilitating the preparation of many types of nanomaterials that cannot be obtained by conventional chemical and physical methods. The EBI on flat graphite pellets resulted in a covering of it surface with rod-like particles composed of different allotropic forms of carbon. Furthermore, the developed system allowed the implantation of the Fe as a catalytic material through steel sputtering of the high voltage acceleration anode during the EBI process. It was observed by HRTEM analyses that the rod-like particles are preferentially composed of highly oriented graphite in its bottom, polycrystalline graphite in its middle and magnetite nanoparticles in its top.
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- 2021
4. Ag Nanoparticles/AgX (X=Cl, Br and I) Composites with Enhanced Photocatalytic Activity and Low Toxicological Effects
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Marcelo Assis, Hirla Costa Silva Fukushima, Amanda F. Gouveia, Juan Andrés, Camila Cristina de Foggi, Tássia Flávia Dias Castro, Francisco C. Groppo Filho, Dayene S. Pimentel, Ricardo Carneiro Borra, João Paulo de Campos da Costa, Elson Longo, and Thaiane Robeldo
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photocatalytic activity ,Materials science ,Ag nanoparticles ,toxicological effects ,silver halides ,Photocatalysis ,General Chemistry ,Nuclear chemistry - Abstract
This is the pre-peer reviewed version of the following article: M. Assis, F. C. Groppo Filho, D. S. Pimentel, T. Robeldo, A. F. Gouveia, T. F. D. Castro, H. C. S. Fukushima, C. C. de Foggi, J. P. C. da Costa, R. C. Borra, J. Andrés, E. Longo. Ag Nanoparticles/AgX (X=Cl, Br and I) Composites with Enhanced Photocatalytic Activity and Low Toxicological Effects, which has been published in final form at https://doi.org/10.1002/slct.202000502. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. Periodic structures induced by electron irradiation are a unique phenomenon when electron beams irradiate on the surface of some materials. These periodic structures have potential for technological applications. However, the fuzzy nature of the electron‐induced structuring hinders its further exploration in such applications. In this paper, novel Ag nanoparticle/AgX (X=Cl, Br and I) composites, with enhanced photocatalytic activity and low toxicological effects, were prepared, for the first time, using electron beam irradiation. The remarkable advantage of this approach is that the Ag nanoparticles/AgX composites can be easily prepared in one‐step without the need for high‐pressure conditions, surfactants, ionic liquids, or reducing agents. Furthermore, our method does not involve any toxic substances, which makes the as‐synthesized samples highly applicable for technological applications. The structure, morphology and physicochemical properties of the Ag nanoparticles/AgX composites were studied using various characterization techniques. Using first‐principles calculations based on density functional theory and the quantum theory of atoms in molecules, we reveal how the concentration of excess electrons in the AgX materials induces the formation of the Ag nanoparticles under electron beam irradiation. These results extend the fundamental understanding of the atomic process underlying the mechanism of Ag−X bond rupture observed during the transformation induced via electron irradiation of the AgX crystals by increasing the total number of electrons in the bulk structure. Thus, our findings provide viable guidance for the realization of new materials for the degradation of contaminated wastewater with low toxicity.
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- 2020
5. Electron beam irradiation for the formation of thick Ag film on Ag3PO4
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Vinícius Teodoro, João Paulo Carmo, Marcelo Assis, Andre Rodrigues, Miguel A. San-Miguel, Juan Andrés, João Paulo de Campos da Costa, Elson Longo, and Camila Cristina de Foggi
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Diffraction ,Materials science ,business.industry ,Scanning electron microscope ,General Chemical Engineering ,Analytical chemistry ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Metal ,symbols.namesake ,Semiconductor ,X-ray photoelectron spectroscopy ,visual_art ,symbols ,visual_art.visual_art_medium ,Surface modification ,Irradiation ,0210 nano-technology ,business ,Raman spectroscopy - Abstract
This study demonstrates that the electron beam irradiation of materials, typically used in characterization measurements, could be employed for advanced fabrication, modification, and functionalization of composites. We developed irradiation equipment using an electron beam irradiation source to be applied in materials modification. Using this equipment, the formation of a thick Ag film on the Ag3PO4 semiconductor is carried out by electron beam irradiation for the first time. This is confirmed by various experimental techniques (X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy) and ab initio molecular dynamics simulations. Our calculations demonstrate that, at the earlier stages, metallic Ag growth is initiated preferentially at the (110) surface, with the reduction of surface Ag cations forming metallic Ag clusters. As the (100) and (111) surfaces have smaller numbers of exposed Ag cations, the reductions on these surfaces are slower and are accompanied by the formation of O2 molecules.
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- 2020
6. EFEITO DO COBALTO E ZINCO EM VARISTORES À BASE DE SNO2
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Glauco Meireles Mascarenhas Morandi Lustosa, João Paulo de Campos da Costa, Leinig Antônio Perazzoli, Biljana Stojanovic, Maria Aparecida Zaghete Bertochi, and Elson Longo
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- 2021
7. Revealing the Nature of Defects in α-Ag2WO4 by Positron Annihilation Lifetime Spectroscopy: A Joint Experimental and Theoretical Study
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João Paulo de Campos da Costa, Marcelo Assis, Carlos Eugenio Macchi, Amanda F. Gouveia, Yara Galvão Gobato, Vinícius Teodoro, Miguel Adolfo Ponce, A. Somoza, Daniele de Souza, Elson Longo, and Juan Andrés
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defects in solids ,nuclear radiation ,irradiation ,010405 organic chemistry ,General Chemistry ,010402 general chemistry ,Condensed Matter Physics ,Nuclear radiation ,01 natural sciences ,0104 chemical sciences ,metal clusters ,Political science ,Pict (programming language) ,General Materials Science ,Humanities ,computer ,defects ,Metal clusters ,Positron annihilation ,computer.programming_language - Abstract
Electron–matter coupling is a fascinating way to tune and modify the properties of materials. In this work, we present a study on the formation and nature of vacancy-like defects in α-Ag2WO4 samples synthesized in a water or ethanol medium and subsequently submitted to electron beam irradiation at different exposure times. To understand the effects on the geometrical and electronic nature of the generated defects, the data obtained by positron annihilation lifetime spectroscopy were interpreted with the aid of first-principles calculations at the density functional theory level. To complement these results, X-ray diffraction, Raman spectroscopy, photoluminescence emissions, and field emission gun scanning electron microscopy techniques were also used. Based on the positron binding energy and the calculated and experimental positron lifetimes, the defect structure of the nonirradiated and irradiated samples was revealed. As a general feature, it was found that the defect structure is more complex for samples synthesized in ethanol than in water. In particular, the results show that all samples contain defects involving Ag vacancies and that the concentration of this type of defect increases with the irradiation time. This work was partly funded by the Fundação de Amparo à Pesquisa do Estado de São Paulo—FAPESP (grants nos. 2013/07296-2 and 2019/01732-1), the Financiadora de Estudos e Projetos—FINEP, Conselho Nacional de Desenvolvimento Cientifico e Tecnológico—CNPq (grants nos. 166281/2017-4 and 426634/2018-7), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior CAPES. J.A. acknowledges Universitat Jaume I (project UJI-B2019-30) and the Ministerio de Ciencia, Innovacio′n y Universidades (Spain) (project PGC2018094417-B-I00) for financially supporting this research. C.M. and A.S. thank the funding from the Agencia Nacional de Promoción Científica y Tecnológica—ANPCyT (Argentina) (PICT 2015-1832), the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires—CICPBA (Argentina), and the Secretaría de Ciencia, Arte y Tecnología, UNCPBA (Argentina).
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- 2021
8. AUMENTO DA ATIVIDADE FOTOCATALÍTICA INDUZIDA POR FILMES HETEROESTRUTURADOS DE TiO2/Pt/SnO2
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Elson Longo da Silva, Glaucio de Oliveira Testoni, Maria Aparecida Zaghete Bertochi Elson Longo da Silva, M. V. Nogueira, Rafael Aparecido Ciola Amoresi, Leinig Antonio Perazolli, Elias de Souza Monteiro Filho, Glauco Meireles, Miguel Ruiz, and João Paulo de Campos da Costa
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- 2020
9. Electron beam irradiation for the formation of thick Ag film on Ag
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João, Paulo de Campos da Costa, Marcelo, Assis, Vinícius, Teodoro, Andre, Rodrigues, Camila, Cristina de Foggi, Miguel Angel, San-Miguel, João Paulo, Pereira do Carmo, Juan, Andrés, and Elson, Longo
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This study demonstrates that the electron beam irradiation of materials, typically used in characterization measurements, could be employed for advanced fabrication, modification, and functionalization of composites. We developed irradiation equipment using an electron beam irradiation source to be applied in materials modification. Using this equipment, the formation of a thick Ag film on the Ag
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- 2020
10. ZnO nanorods-gold nanoparticle-based biosensor for detecting hepatitis C
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Glenda Biasotto, João Paulo de Campos da Costa, Maria Aparecida Zaghete, Paulo Inácio da Costa, and Universidade Estadual Paulista (Unesp)
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010302 applied physics ,Detection limit ,Materials science ,Biosensor device ,Nanoparticle ,Substrate (chemistry) ,Nanotechnology ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0103 physical sciences ,Electrode ,Hydrothermal synthesis ,General Materials Science ,Nanorod ,0210 nano-technology ,Biosensor - Abstract
Made available in DSpace on 2020-12-12T01:00:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ZnO nanorods comprised of biosensors with Au nanoparticles are described in this study for detecting Hepatitis C virus (HCV). The biosensor device was constructed on a glass substrate with silver and gold electrodes. The ZnO nanorods were grown by microwave hydrothermal synthesis, and the Au nanoparticles were deposited by the sputtering method. The Au nanoparticles were deposited because of the right efficient of anti-HCV antibodies with cystamine and glutaraldehyde. The ZnO nanorods were evaluated using SEM images. The electrochemical biosensor shows a sensitive response to HCV with a detection limit of 0.25 μg/μL. The proposed sensor characteristics of high specificity, good reproducibility and remarkable stability will provide a sensitive, selective, and convenient approach for the detection of HCV. LIEC Institute of Chemistry São Paulo State University-UNESP School of Pharmaceutical Sciences São Paulo State University-UNESP LIEC Institute of Chemistry São Paulo State University-UNESP School of Pharmaceutical Sciences São Paulo State University-UNESP FAPESP: 2016/05269-6
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- 2019
11. Increased photocatalytic activity induced by TiO 2 /Pt/SnO 2 heterostructured films
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Maria Aparecida Zaghete, Glauco M. M. M. Lustosa, João Paulo de Campos da Costa, Glaucio de Oliveira Testoni, Rafael Aparecido Ciola Amoresi, M. V. Nogueira, Miguel Ruiz, Leinig Antonio Perazolli, and Universidade Estadual Paulista (Unesp)
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Materials science ,Schottky barrier ,chemistry.chemical_element ,Oxides ,Heterojunction ,02 engineering and technology ,General Chemistry ,Interface ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electrophoretic deposition ,Chemical engineering ,chemistry ,Sputtering ,Photocatalysis ,General Materials Science ,0210 nano-technology ,Platinum ,Layer (electronics) ,Deposition (law) ,Films - Abstract
Made available in DSpace on 2018-12-11T17:35:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In this work, a high photocatalytic activity was attained by intercalating a Pt layer between SnO2 and TiO2 semiconductors, which yielded a TiO2/Pt/SnO2 - type heterostructure used in the discoloration of blue methylene (MB) solution. The porous films and platinum layer were obtained by electrophoretic deposition and DC Sputtering, respectively, and were both characterized morphologically and structurally by FE-SEM and XRD. The films with the Pt interlayer were evaluated by photocatalytic activity through exposure to UV light. An increase in efficiency of 22% was obtained for these films compared to those without platinum deposition. Studies on the reutilization of the films pointed out high efficiency and recovery of the photocatalyst, rendering the methodology favorable for the construction of fixed bed photocatalytic reactors. A proposal associated with the mechanism is discussed in this work in terms of the difference in Schottky barrier between the semiconductors and the electrons transfer and trapping cycle. These are fundamental factors for boosting photocatalytic efficiency. Interdisciplinary Laboratory of Electrochemistry and Ceramics LIEC – Chemistry Institute São Paulo State University - UNESP Laboratory of Photocatalysis and Microwave Sintering – Chemistry Institute São Paulo State University - UNESP Interdisciplinary Laboratory of Electrochemistry and Ceramics LIEC – Chemistry Institute São Paulo State University - UNESP Laboratory of Photocatalysis and Microwave Sintering – Chemistry Institute São Paulo State University - UNESP FAPESP: 2013/07296-2
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- 2018
12. Portable laboratory platform with electrochemical biosensors for immunodiagnostic of hepatitis C virus
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João Paulo de Campos da Costa, Paulo Inácio da Costa, W.B. Bastos, João Paulo Carmo, Maria Aparecida Zaghete, Elson Longo, Universidade de São Paulo (USP), Universidade Federal de São Carlos (UFSCar), and Universidade Estadual Paulista (Unesp)
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Horizontal scan rate ,Materials science ,Potassium ferrocyanide ,010401 analytical chemistry ,Analytical chemistry ,portable laboratory platform ,Early diagnosis ,01 natural sciences ,Potentiostat ,0104 chemical sciences ,law.invention ,Bluetooth ,chemistry.chemical_compound ,chemistry ,law ,ENGENHARIA ELÉTRICA ,Sensitivity (control systems) ,Electrical and Electronic Engineering ,Cyclic voltammetry ,Connection (algebraic framework) ,hepatitis C ,Instrumentation ,Biosensor ,electrochemical biosensors - Abstract
Made available in DSpace on 2020-12-12T01:42:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-15 This paper presents a portable laboratory platform (PLP) with electrochemical amperometric biosensors for the detection of hepatitis C virus (HCV). This PLP is composed by a controller unit, a Bluetooth module to provide communication with mobile devices, and a potentiostat circuit to perform cyclic voltammetry. The Bluetooth communication allows the mobile devices to set up the parameters, e.g., a cycling voltage in the range ±1.5 V, a scan rate in the range 5-1000 mV-1 with a step potential of 2.318 mV, and up to 4000 number of scan cycles. The electrochemical sensors were functionalized with cystamine (C4H12N2S2) and glutaraldehyde (C5H8O2) to make the covalent binding with the recombinant core-HCV protein. The experimental results have revealed a positive detection of HCV, using a redox solution of 5 mmol.L-1 of potassium ferrocyanide (K3 Fe(CN)6) on 0.1 mol.L-1 of phosphate-buffered saline (PBS). The sensitivity of the immunosensor was established at the concentration of 1 ng. μ L-1 of the anti-core-HCV IgG class antibody. This PLP has a plug-and-play connection for the biosensors, and at the same time, it offers good ergonomy with easy operation due to its low dimensions (115 mm × 75 mm × 30 mm). This PLP presents a power consumption of 280.5 mW when supplied with a 3.3-V voltage source. This consumption was measured in the worst operation case, e.g., with the Bluetooth working, resulting in an average battery life of 195 min. Department of Electrical Engineering (SEL) University of São Paulo (USP) Department of Chemistry INCTMN-CDMF Federal University of São Carlos (UFSCar) Department of Clinical Analysis School of Pharmaceutical Sciences Laboratory of Clinical Immunology and Molecular Biology (LICBM) São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP) Department of Clinical Analysis School of Pharmaceutical Sciences Laboratory of Clinical Immunology and Molecular Biology (LICBM) São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP)
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- 2019
13. Surface-dependent photocatalytic and biological activities of Ag2CrO4: Integration of experiment and simulation
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Elson Longo, Vinícius Teodoro, Ricardo Carneiro Borra, Amanda F. Gouveia, Iván Sorribes, Marcelo Assis, Camila Cristina de Foggi, Priscila Fernanda Caperucci, Carlos A. Silva, João Paulo de Campos da Costa, Carlos Eduardo Vergani, Thaiane Robeldo, Juan Andrés, Miguel A. San-Miguel, Universidade Federal de São Carlos (UFSCar), Universidade Estadual de Campinas (UNICAMP), Universidade Estadual Paulista (Unesp), Universitat Jaume I, and Ministerio de Ciencia, Innovación y Universidades (España)
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Morphology ,Photoluminescence ,Materials science ,General Physics and Astronomy ,Photocatalytic and biological activities ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Crystal ,First-principles calculations ,chemistry.chemical_compound ,Rhodamine B ,Photodegradation ,Wulff construction ,Surfaces and Interfaces ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surface energy ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,Chemical engineering ,Photocatalysis ,Density functional theory ,Ag2CrO4 ,0210 nano-technology - Abstract
In this work, we present a joint experimental and theoretical study towards unveiling the photocatalytic (photodegradation of Rhodamine B), the antifungal (towards Candida glabrata) and cytotoxicity (against the L929 cell line) of Ag2CrO4. X-ray diffraction, Rietveld refinements, micro-Raman, UV–Visible spectroscopies, and photoluminescence emissions have been employed to characterize the as-synthetized samples by a co-precipitation method in water and ammonia. To complement and rationalize the experimental results, first-principles calculations have been performed within the framework of density functional theory. The crystal morphologies were characterized by field emission scanning electron microscopy images, while the Wulff construction, obtained by the calculated values of the surface energy, was employed to model and match the experimental images by tuning the relative stability of the exposed surfaces. This experimental and theoretical study provides a detailed understanding of the transformations of morphology and can aid in the development of the surface-dependent photocatalytic and biological activities of Ag2CrO4. We believe that our results offer new insights regarding the local coordination of superficial Ag and Cr cations on each exposed surface of the corresponding morphology, provided some general principles for material design, that dictate the properties of Ag2CrO4, a field that has so far remained unexplored., This work was funded in part by Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP (2013/07296-2; 2016/23891-6; 2017/12594-3; 2017/12594-3; 2019/01732-1; 2019/13507-2), FINEP, Conselho Nacional de Desenvolvimento Cientifico e Tecnológico - CNPq (166281/2017-4), and CAPES. This work used computational resources of the “Centro Nacional de Processamento de Alto Desempenho em São Paulo” (CENAPAD-SP), “Centro de Computação John David Rogers” (CCJDR-UNICAMP), and the CENAPAD-RJ (SDumont). J.A. acknowledges Universitat Jaume I (project UJI-B2019-30), and the Ministerio de Ciencia, Innovación y Universidades (MICIU) (project PGC2018094417-B-I00) for financially supporting this research. I. S. thanks the Spanish Ministerio de Economía, Industria y Competitividad (MINECO) for a postdoctoral “Juan de la Cierva-Incorporación” fellowship (IJCI-2016-30590), and the financial support from MICIU through the “José Castillejo” Mobility Program (CAS19/00339).
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- 2021
14. Portable laboratory platform and electrochemical biosensors applied in the immunodiagnostic of hepatitis C virus
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João Paulo de Campos da Costa, João Paulo Pereira do Carmo, Wagner Benício Bastos, and Maria Aparecida Zaghete Bertochi
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A hepatite C é uma doença caracterizada pela inflamação do fígado, decorrente da infecção viral pelo VHC, e uma das maiores epidemias virais da humanidade. Atualmente o diagnóstico e tratamento da doença possui um elevado custo para o sistema público de saúde, sendo a principal causa de transplante de fígado em todo o mundo. Por este motivo, é incentivado o desenvolvimento de diagnósticos para a detecção nas fases iniciais da infecção, que possam auxiliar no tratamento e até mesmo na cura da doença. Os biossensores baseados em métodos eletroquímicos de detecção vem se destacando na área de diagnóstico devido às suas características de maior estabilidade e sensibilidade, e um baixo custo de fabricação e miniaturização. O presente trabalho relata o desenvolvimento de uma plataforma laboratorial portátil com biossensores eletroquímicos amperométricos. Aproveitando o conhecimento prévio de técnicas de fabricação (silkscreen, sputtering e placa de circuito impresso), otimizou-se o projeto e respectivo fabrico de biossensores específicos para aplicação nesta plataforma laboratorial. No âmbito do desenvolvimento deste projeto, o interesse foi definir os processos mais adequados à produção em larga escala de biossensores e validar a plataforma em comparação com equipamentos comerciais para a sua aplicação em um teste imunodiagnóstico da infecção pelo vírus da hepatite C. Os resultados obtidos mostraram que a técnica de placa de circuito impresso apresentou melhores vantagens em comparação com as técnicas de sputtering e silkscreen além de permitir uma fácil integração com a plataforma laboratorial portátil. A plataforma de laboratório portátil desenvolvida inclui uma unidade microcontrolada responsável pelo controle e transferência de dados das reações eletroquímicas, um módulo Bluetooth para transmissão de dados para dispositivos móveis e uma interface potenciostática. O sistema desenvolvido mostrou-se adequado para uso em testes eletroquímicos e aplicação no imunodiagnóstico da hepatite C. Hepatitis C is a disease characterized by inflammation of the liver resulting from viral infection by HCV and one of the largest viral epidemics in mankind. Currently the diagnosis and treatment of the disease has a high cost for the public health system, being the main cause of liver transplantation worldwide. For this reason, it is encouraged the development of diagnostics for detection in the early stages of infection, which may aid in the treatment and even cure of the disease. Biosensors based on electrochemical detection methods have been prominent in the diagnostic area due to their characteristics of greater stability and sensitivity, and a low manufacturing and miniaturization cost. The present work reports the development of a portable laboratory platform with electrochemical amperometric biosensors. Taking advantage of the prior knowledge of manufacturing techniques (silkscreen, sputtering and printed circuit board), the design and respective manufacture of specific biosensors for application in this laboratory platform was optimized. In the development of this project, the interest was to define the most appropriate processes for the large-scale production of biosensors and to validate the platform in comparison with commercial equipment for its application in an immunodiagnostic test of the hepatitis C virus infection. The results obtained showed that the printed circuit board technique presented better advantages compared to the sputtering and silkscreen techniques in addition to allowing easy integration with the portable laboratory platform. The portable laboratory platform developed includes a microcontroller unit responsible for controlling and transferring electrochemical reactions data, a Bluetooth module for data transmission to mobile devices and a potentiostatic interface. The developed system proved to be suitable for use in electrochemical tests and immunodiagnostic application of hepatitis C.
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- 2018
15. α- and β-AgVO3 polymorphs as photoluminescent materials: an example of temperature-driven synthesis
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Lourdes Gracia, João Paulo de Campos da Costa, Máximo Siu Li, Maya Penha, Elson Longo, Regiane Cristina de Oliveira, Juan Andrés, Mayara Mondego Teixeira, Jussara Soares da Silva, and Eric Mark Francisco
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Photoluminescence ,Materials science ,Process Chemistry and Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,polymorphism ,α-AgVO3 ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,ESTRUTURA ELETRÔNICA ,Transformation (function) ,Phase (matter) ,β-AgVO3 ,Materials Chemistry ,Ceramics and Composites ,Physical chemistry ,photoluminescence ,Beta (velocity) ,0210 nano-technology ,Monoclinic crystal system - Abstract
Controlling the synthesis of a given polymorph of an inorganic material is a further step in the design of property and function. In this letter, we report for the first time a simple procedure to effectively control the reversible transformation between the crystalline polymorphs α-AgVO3 and β-AgVO3. Photoluminescence emission (PL) performance is analyzed; at low temperatures (up to 35 °C) when α-AgVO3 is formed the PL emission is red, while at temperatures larger than 45 °C when β-AgVO3 is obtained the color of emission PL emission goes from green to blue. The findings highlight the ability of temperature to dramatically alter the nature of phase transformation at the atomic level. The phase transformation is driven by the short-range structural and electronic changes of [VO4] and [AgOx] (x = 5, 6, and 7) clusters (building blocks of both monoclinic structures), and hence is dependent on the temperature employed during synthesis. These outcomes clearly demonstrate that the AgVO3 crystals exhibited appropriate activity for application in visible lamps, displays, and other optical devices.
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- 2018
16. Potential Barrier of (Zn,Nb)SnO2 -Films Induced by Microwave Thermal Diffusion of Cr3+ for Low-Voltage Varistor
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Biljana Stojanović, Glauco M. M. M. Lustosa, Leinig Antonio Perazolli, João Paulo de Campos da Costa, and Maria Aparecida Zaghete
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010302 applied physics ,Materials science ,Diffusion ,Analytical chemistry ,Varistor ,02 engineering and technology ,Substrate (electronics) ,Conductivity ,021001 nanoscience & nanotechnology ,Thermal diffusivity ,01 natural sciences ,Electrical resistivity and conductivity ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,Rectangular potential barrier ,Grain boundary ,0210 nano-technology - Abstract
The effect of Cr3+ on the electrical properties of SnO2-based films deposited by electrophoresis on Si/Pt substrate was considered. The films were sintered in a microwave oven at 1000°C/40 min and then the surface was modified with deposition of Cr3+ ions by electrophoresis. The diffusion of Cr3+ contributes to the modification of the potential barrier formed on the grain boundary improving the electrical properties due to electron acceptor species adsorption on the grain boundary. The influence on the properties of grain boundary was verified by I versus V characterization in as a function of temperature. The films showed nonlinear coefficient over 9, potential barrier height over 0.5 eV and resistivity greater than 107 Ω·cm. 4 samples were prepared at same conditions and presented similar electrical behavior, showing the efficiency of technique on reproducibility to varistor properties control. Thereby the nonlinear coefficient increases while decreasing the conductivity of the system is noticed.
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- 2015
17. A biopotential amplifier in CMOS for neural recording on optogenetics applications
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João Paulo de Campos da Costa, Y. A. O. Assagra, Rodrigo Henrique Gounella, T. C. Granado, and João Paulo Carmo
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business.industry ,Computer science ,Interface (computing) ,Amplifier ,010401 analytical chemistry ,Electrical engineering ,Optogenetics ,Chip ,01 natural sciences ,0104 chemical sciences ,CMOS ,Power consumption ,business ,Bioamplifier ,Voltage - Abstract
This paper reports on the design and simulation of a bioamplifier, which can amplify bio-signals in the range of 1Hz up to 10kHz while rejecting DC offsets generated at the interface between electrodes and tissue. The fully-integrated bio-amplifier was designed in the 2 metals/1 poly 0.7μm CMOS process from the on-semiconductor. The bioamplifier shows a gain of 39.8dB in the range from 100Hz to 6kHz. The area consumed by the amplifier is around 0.36mm2 of chip area, and the power consumption of the system is around 37μW from a 5V voltage supply.
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- 2017
18. Optical CMOS sensor for angular measurements with readout electronics
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José Higino Correia, R. T. Machado, T. C. Granado, João Paulo Carmo, Y. A. O. Assagra, João Paulo de Campos da Costa, and Rodrigo Henrique Gounella
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Angle of rotation ,CMOS sensor ,Materials science ,business.industry ,020209 energy ,Photovoltaic system ,Physics::Optics ,Readout electronics ,02 engineering and technology ,Tracking (particle physics) ,7. Clean energy ,Solar tracker ,Photodiode ,law.invention ,CMOS ,law ,0202 electrical engineering, electronic engineering, information engineering ,Optoelectronics ,business - Abstract
This paper presents an optical sensor for angular measurements to perform precise tracking of the sun's incident angle in a photovoltaic system. This microdevice was designed using a 0.18μm CMOS technology from TSMC. The microdevice is composed by a matrix of photodiodes and their respective readout electronics. A set of microstructures were used to resolve the angles of rotation by measuring the angle of incident light in the microdevice. These microstructures were fabricated on top of the photodiodes using the same CMOS process. Simulations and experimental setup showed the possibility of taking measurements from the angles between −60 to 60 degrees.
- Published
- 2017
19. A RF mixer using 0.7μm CMOS for intra-corporal communication devices
- Author
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Y. A. O. Assagra, João Paulo Carmo, T. C. Granado, João Paulo de Campos da Costa, and Daniel R. Celino
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Gilbert cell ,Digital down converter ,Computer science ,business.industry ,Electrical engineering ,020206 networking & telecommunications ,Topology (electrical circuits) ,02 engineering and technology ,Noise figure ,CMOS ,0202 electrical engineering, electronic engineering, information engineering ,Figure of merit ,business ,Frequency mixer ,ISM band - Abstract
This paper presents an up/down converter double-balanced Gilbert cell mixer for frequencies of 433, 870 and 928 MHz in the ISM band (industrial, scientific and medical). This mixer was designed with the on-semiconductor (former AMIS) 0.7μm CMOS technology. The Gilbert cell topology was selected due to its good figure of merit (FOM), which takes into account parameters such as the conversion gain (CG), isolation between the input ports, linearity and the noise figure. This mixer provides frequency translation by means of a true multiplication on four quadrants. The simulations showed a total power consumption of 3mW from a power supply of 5V, a CG of 10.5dB, an input referred third-order input intercept point (IIP3) of 29.72dBm and an input referred 1-dB compression point (IP1dB) of 13.15dBm. This paper also presents a comparison for the three bands in order to confirm the scalability and suitability of the mixer implemented. The target application of this mixer is to provide communication to/from intra-corporal communication devices.
- Published
- 2017
20. CMOS developments for photonic modules on endoscopic capsules
- Author
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T. C. Granado, Y. A. O. Assagra, João Paulo Carmo, João Paulo de Campos da Costa, and Rodrigo Henrique Gounella
- Subjects
020203 distributed computing ,Medical treatment ,Computer science ,business.industry ,Readout electronics ,02 engineering and technology ,Photodiode ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,CMOS ,law ,0202 electrical engineering, electronic engineering, information engineering ,Optoelectronics ,Microelectronics ,030211 gastroenterology & hepatology ,Gastrointestinal tissue ,Photonics ,business ,Cmos process - Abstract
This paper presents few developments on CMOS microelectronics for the implementation of photonic modules on endoscopic capsules (ECs). The first microelectronic system was developed with the goal to allow photodynamic therapy (PDT) on ECs. This first system was designed in the 2-metals/1-poly 0.7μm CMOS process from the on-semiconductor. The second development is an optical sensor designed for spectroscopy analysis on ECs from diffuse reflectance light originated in the gastrointestinal tissue. This second system was designed in the mixed-signal/RF 0.18μm CMOS general process from the Taiwan Semiconductor (TSMC).
- Published
- 2017
21. Optical filters for narrow-band imaging on medical devices
- Author
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João Paulo de Campos da Costa, Y. A. O. Assagra, Manuel Silva, José Higino Correia, T. C. Granado, R. H. Gonnella, and João Paulo Carmo
- Subjects
010302 applied physics ,Materials science ,business.industry ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Wavelength ,Ellipsometry ,law ,Filter (video) ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,Optical filter ,business ,Refractive index ,Passband ,Light-emitting diode - Abstract
This paper presents optical filters for narrow-band imaging on medical devices. Two optical filters were designed to provide an extremely narrow passband around the 415 nm (blue) and 540 nm (green) wavelengths using the Fabry-Perot phenomenon. Each filter is composed by successive thin-film layers of dielectric materials of titanium dioxide (TiO2) and silicon dioxide (SiO2). The TiO2 and SiO2 that compose the thin-films were fully characterized by ellipsometry applied within the 250–1700 nm wavelength range. The optical performance of the blue NBI optical filter (415 nm) was also measured. These filters were developed to integrate with light emitting diodes (LED) to provide the desired narrow-band imaging (NBI) bands on medical devices.
- Published
- 2017
22. Electrical Properties at Grain Boundaries Influenced by Cr3+Diffusion in SnO2.ZnO.Nb2O5-Films Varistor Prepared by Electrophoresis Deposition
- Author
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João Paulo de Campos da Costa, Maria Aparecida Zaghete, Glauco M. M. M. Lustosa, and Leinig Antonio Perazolli
- Subjects
Electrophoresis ,Materials science ,Diffusion ,Analytical chemistry ,Mineralogy ,Varistor ,Grain boundary ,Microbiology ,Deposition (chemistry) - Abstract
SnO2-based varistors are strong candidates to replace the ZnO-based varistors due to ordering fewer additives to improve its electrical behavior as well as by showing similar nonlinear characteristics of ZnO varistors. In this work, SnO2-nanoparticles based-varistors with addition of 1.0 %mol of ZnO and 0.05 %mol of Nb2O5were synthesized by chemical route. SnO2.ZnO.Nb2O5-films with 5 μm of thickness were obtained by electrophoretic deposition (EPD) of the nanoparticles on Si/Pt substrate from alcoholic suspension of SnO2-based powder. The sintering step was carried out in a microwave oven at 1000 °C for 40 minutes. Then, Cr3+ions were deposited on the films surface by EPD after the sintering step. Each sample was submitted to different thermal treatments to improve the varistor behavior by diffusion of ions in the samples. The films showed a nonlinear coefficient (α) greater than 9, breakdown voltage (VR) around 60 V, low leakage current (IF≈ 10-6A), height potential barrier above 0.5 eV and grain boundary resistivity upward of 107Ω.cm.
- Published
- 2014
23. Electrochemical immunosensor based on ZnO nanorods-Au nanoparticles nanohybrids for ovarian cancer antigen CA-125 detection
- Author
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Paulo Inácio da Costa, João Paulo de Campos da Costa, Talita Mazon, Gisane Gasparotto, and Maria Aparecida Zaghete
- Subjects
Working electrode ,Materials science ,Nanoparticle ,Metal Nanoparticles ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Biosensing Techniques ,01 natural sciences ,Biomaterials ,medicine ,Hydrothermal synthesis ,Humans ,Immunoassay ,Ovarian Neoplasms ,Nanotubes ,medicine.diagnostic_test ,010401 analytical chemistry ,Substrate (chemistry) ,Reproducibility of Results ,Electrochemical Techniques ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Mechanics of Materials ,Colloidal gold ,CA-125 Antigen ,Electrode ,Nanorod ,Female ,Gold ,0210 nano-technology - Abstract
In this research, ZnO nanorods - Au nanoparticles nanohybrids have been fabricated and employed to sensitive electrochemical strategy for the specific detection of the ovarian cancer antigen CA-125/MUC126. The microdevice was developed in our lab based on gold and silver electrodes sputtered on glass substrate. The ZnO nanorods arrays were grown on working electrode using assisted microwave hydrothermal synthesis than gold nanoparticles (Au NPs) were deposited by sputtering. The Au NPs onto ZnO nanorods surface provides a favorable platform for efficient loading of anti-CA-125 antibody via binding with cystamine and glutaraldehyde. The effective loading of the biological material (CA-125 antibody and antigen) on the matrix was observed by SEM images. The electrochemical immunosensor shows a sensitive response to ovarian cancer antigen recombinant human CA-125/MUC126 with detection of 2.5ng/μL, 100 times lower than immunoblot system. Due to high specificity, reproducibility and noteworthy stability, the developed sensor will provide a sensitive, selective and convenient approach to be used to detect CA-125/MUC126.
- Published
- 2016
24. New Approaches to Preparation of SnO2-Based Varistors — Chemical Synthesis, Dopants, and Microwave Sintering
- Author
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GisaneGasparotto, Natalia Jacomaci, Maria Aparecida Zaghete, Leinig Antonio Perazolli, Glauco M. M. M. Lustosa, and João Paulo de Campos da Costa
- Subjects
Materials science ,Dopant ,Inorganic chemistry ,Varistor ,Sintering ,chemistry.chemical_element ,Microstructure ,Engineering physics ,chemistry ,visual_art ,visual_art.visual_art_medium ,Breakdown voltage ,Electronics ,Ceramic ,Tin - Abstract
Tin oxides have applications such as sensors, solar cells, transistors, and varistors, which are being studied to replace ZnO varistors due to similar electrical properties, simpler microstructure, no formation of secondary phases, and lower concentration of agent modifiers to promote the varistor characteristics and densification. Varistors are ceramic with a high concentration of structural and electronics defects. The type and the amount of defects are related with agent modifiers and processing steps employed. The study in materials processing aims to improve the ceramics properties. Chemical synthesis ensures the homogeneous distribution of dopants used to promote electrical and structural properties. Microwave sintering appears as processing to optimize time and sintering temperature. Varistor application is linked to its breakdown voltage, which should be larger than the operating voltage. In an operating range of 1 kV to 1 MV, the varistors are used in electricity transmission networks. In a range of 24–1000 V, the application occurs in electronics and appliances and in a range smaller than 24 V, as protective of automotive electronics and computers. This chapter aims to provide information on new processing steps for the production of SnO2 varistors and to show the possibility to get electrical properties with non-ohmic characteristic for technological applications.
- Published
- 2015
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