Paulo Moscon | Universidade Federal do Espirito Santo (original) (raw)

Papers by Paulo Moscon

Revista Brasileira de Ensino de Física

Um aparato experimental para a obtenção de curvas de histerese magnética foi construído, com a pa... more Um aparato experimental para a obtenção de curvas de histerese magnética foi construído, com a participação de estudantes de licenciatura em física, visando uma visualização dos fundamentos que caracterizam a resposta magnética de materiais ferromagnéticos submetidos a campos magnéticos alternados. Foram obtidos laços de histereses do núcleo secundário de um transformador, visualizando-os na tela de um osciloscópio na forma gráfica de tensão em um capacitor conectado ao enrolamento secundário em função da tensão medida em um resistor conectado ao enrolamento primário. Os laços foram obtidos para cinco valores de tensão aplicadas ao primário do transformador na faixa de 160–220 V. Foi observado um aumento nos campos coercivo, remanente e magnetização máxima com o aumento da tensão no primário. As curvas de permeabilidade magnética relativa apresentam um máximo próximo aos valores de campo coercivo, e assim observou-se a não linearidade da permeabilidade com o campo intensidade magnét...

Brazilian Journal of Development

A proposta deste trabalho é estimular o aprendizado em física de alunos do ensino médio e despert... more A proposta deste trabalho é estimular o aprendizado em física de alunos do ensino médio e despertar os seus interesses pela área de pesquisa em ciências físicas. Eles são orientados por professores e monitores a construir experimentos de física, usando ferramentas adequadas. Esta prática extracurricular os ajudam a compreender a importância que os fenômenos físicos associados aos experimentos apresentam no mundo moderno e, em seus cotidianos. Desta prática, foi observado que a abordagem de conteúdos pela experimentação torna a aula de física mais dinâmica. Neste caso, o aluno monitor teve um papel fundamental, onde o mesmo participou efetivamente das discussões dos conteúdos. O aluno monitor foi instigado a entender os fenômenos físicos que envolvem a experiência. Com este trabalho vemos indicações de que é possível despertar a curiosidade pelo aprendizado e traçar metas que superam as formas tradicionais usadas em sala. Este trabalho faz parte de um projeto desenvolvido entre a Uni...

carga ligada ao gerador, (ii) a frequˆencia de rota¸c˜ao do gerador ´e mantida constante, (iii) a... more carga ligada ao gerador, (ii) a frequˆencia de rota¸c˜ao do gerador ´e mantida constante, (iii) a tens˜ao nos terminais de uma carga resistiva ´e constante e (iv) o caso e que se ﬁxa um valor de resistˆencia e aumenta a frequˆencia de rota¸c˜ao do gerador. Os resultados experimentais concordam com os fundamentos te´oricos abordados nos cursos cl´assicos de eletromagnetismo. O experimento constituiu uma importante ferramenta para a associa¸c˜ao dos conceitos te´oricos abstratos com a intui¸c˜ao pr´atica no ensino experimental do eletromagnetismo. Palavras-chave: Ensino, Constru¸c˜ao, Gerador El´etrico, For¸ca Eletromotriz, Potˆencia. Electric generators are potential topics to be applied in teaching and learning physics. They are the source of all modern technology and are part of everyday life for students. Therefore, in this work, a didactic alternating current electric generator of low cost, was produced, in which it was possible to approach the generation of electric energy and t...

Revista Brasileira de Ensino de Física, 2022

Dentre os diversos dispositivos tecnológicos desenvolvidos a partir do advento do eletromagnetism... more Dentre os diversos dispositivos tecnológicos desenvolvidos a partir do advento do eletromagnetismo, os geradores elétricos estão entre os que envolvem a maior parte de suas fundamentações teóricas, condensadas nas equações de Maxwell do eletromagnetismo. Considerando que são dispositivos do cotidiano dos estudantes, neste trabalho produziu-se um gerador elétrico didático de corrente alternada de baixo custo, no qual foi possível associar a geração da energia elétrica com as equações do eletromagnetismo que regem este fenômeno. Adicionalmente, estudou-se as grandezas relacionadas associando a força eletromotriz com potência e corrente elétricas em um circuito resistivo. Analisou-se a relação entre estas grandezas nos casos em que: (i) não há carga ligada ao gerador, (ii) a frequência de rotação do gerador é mantida constante, (iii) a tensão nos terminais de uma carga resistiva é constante e (iv) o caso e que se fixa um valor de resistência e aumenta a frequência de rotação do gerador...

Brazilian Journal of Development, 2021

This study reports on physicochemical properties (total soluble solids, titratable acidity plus c... more This study reports on physicochemical properties (total soluble solids, titratable acidity plus caffeine, trigonelline, 5-CQA, and total phenols contents) of five genotypes of Robusta coffee beans; Bamburral, Beira Rio, Clementino, Coringa, and Pirata. Green bean of Clementino presents the highest concentration of total soluble solids in dry basis (18.0%) and the lowest titratable acidity (154.0 mL-NaOH). Moreover, green beans of Clementino and Pirata show intermediate values of caffeine and trigonelline contents while presenting the highest yield index ofstable free radical formation after roasting, respectively equal to 26 and 23 (electron paramagnetic resonance-EPR data), and the highest content of 5-CQA (around 42 mg/g). Green beans of Bamburral, Beira Rio and Coringa show the highest concentration of total phenols (53-56 mg/g), meaning the highest antioxidant activities (IC50 test) but reduced yield index of formation of stable free radicals after roasting, respectively equal to 13.0, 5.9, and 13.0 (EPR data).

Journal of Superconductivity and Novel Magnetism, 2021

The magnetic properties of oil constituents appear to be related to their key physical and chemic... more The magnetic properties of oil constituents appear to be related to their key physical and chemical properties; therefore, the application of new magnetic characterization techniques for oils can make additional contributions to the field. In this study, despite the high dilution of 3d-like ions in crude oil, magnetic susceptibility measurements, recorded at different temperatures and frequencies, and electronic paramagnetic resonance measurements below room temperature were applied to detection of magnetic nanoparticles naturally found in distinctive dehydrated crude oils from the same geological reservoir, but from different oil wells. Electronic paramagnetic resonance measurements probed the presence of Fe3+ ions, with characteristics attributed to magnetite or maghemite (γ-Fe2O3) magnetic nanoparticles in super paramagnetic regime, whilst the presence of a magnetic susceptibility peak, that is visible only at 5000 Hz, has indicated a magnetically blocked regime, via Brownian relaxation, of iron-oxide magnetic nanoparticles. The magnetic susceptibility data showed that it is possible to distinguish the particle size distribution homogeneity and, with the support of the electron paramagnetic resonance technique, the relative fractions of iron-oxide magnetic nanoparticles in crude oils. Thus, these findings show that the magnetic susceptibility technique, supported by electronic paramagnetic resonance spectroscopy, can be applied for the study of magnetic nanoparticles in crude oils and can aid in determining and understanding the fundamental properties of crude oils.

Agricultural Sciences, 2018

Blucher Physics Proceedings, 2018

Materials Research Express, 2019

Research, Society and Development, 2019

In this article a bibliometric analysis of spinel ferrite production was carried out, with the pu... more In this article a bibliometric analysis of spinel ferrite production was carried out, with the purpose of to expanding the knowledge management on the research area, also identify future perspectives turned to the application of such structures and light to dry research. The study was designed based on a statistical and qualitative analysis of Web of Science (WoS) database documents from 1995-2017, using as an additional tool the CiteSpace software, which allows the expansion of the domain of knowledge on the subject With the acquirement of a set of bibliographic records of relevant publications, with subsequent identification of interlinked research groups (clusters). The CiteSpace software provides a set of empirical parameters, among them the so-called Betweenness Centrality (BC), which describes the influence of a given article on the transfer of information between the set of publications under study. Through the results it was possible to identify significant growth in the nu...

Physica B: Condensed Matter, 2019

Abstract This work reports a magnetic anisotropy study, using ferromagnetic resonance (FMR), of n... more Abstract This work reports a magnetic anisotropy study, using ferromagnetic resonance (FMR), of nickel ferrite magnetic nanoparticles produced by the sol-gel protein technique and annealed at temperatures (TA) of 600 °C, 900 °C, and 1100 °C. Theoretical fittings of the FMR lines were achieved by considering a four-fold symmetry model for randomly dispersed magnetic nanoparticles. The FMR results agree with Xray diffraction data and confirm that: (i) the crystalline structure of Ni ferrite particles increases proportionally with the annealing temperature; (ii) the intensity of the cubic anisotropy field (Hk = 2 K1/Ms) also changes evolving from positive (+680 Oe, for TA = 600 °C) to negative (−1600 Oe, for TA = 1100 °C) values, implying that the orientation of the easy axis of magnetization within the particles changes from the {100} to the {111} directions; and (iii) the decrease in the linewidth, from 1640 to 900 Oe, of the terms used in the FMR modeling, evidence the increase in crystallinity as a function of the heat treatment. This fact combined with the evolution of the values of the anisotropy fields to their negative bulk value, previously known from the literature, suggests a redistribution of the Ni/Fe ions, initially in metastable states, tending to the configuration of greater stability of the system.

RSC Adv., 2015

Magnetic nanosheets can be easily synthesized without the use of templates by adding glycerol as ... more Magnetic nanosheets can be easily synthesized without the use of templates by adding glycerol as an intermediate for the nanosheets production.

Journal of Physics D: Applied Physics, 2009

Localization and magnetism of Fe replacing either Mn or Ni in the Ni 2 Mn 1.44 Sn 0.56-type Heusl... more Localization and magnetism of Fe replacing either Mn or Ni in the Ni 2 Mn 1.44 Sn 0.56-type Heusler alloy have been systematically investigated using magnetization, scanning electron microscopy and Mössbauer spectroscopy. It has been shown that the addition of Fe either in Mn or in Ni sites reduces the fraction of the Mn-rich NiMnSn-type Heusler alloys that has short-range antiferromagnetic interactions; consequently it reduces the martensitic-austenitic transition temperature and increases the thermal hysteresis width due to an increase in atomic disorder caused by Fe replacements. The Fe atoms in Mn sites have two magnetic configurations with magnetic moments of 0.8µ B /Fe and 1.4µ B /Fe in the martensitic orthorhombic structure, while Fe in Ni sites have magnetic moments smaller than 0.1µ B /Fe. These results indicate that the Fe atoms are distinctly substituting either Mn or Ni and the decrease in the martensitic phase transition temperature for increasing Fe content can be mainly attributed to the Fe atoms in the Mn sites in both cases.

Journal of Applied Physics, 2008

Mössbauer spectroscopy, in a broad temperature interval of 12-425 K, has been applied to investig... more Mössbauer spectroscopy, in a broad temperature interval of 12-425 K, has been applied to investigate the spin reorientation dynamics caused by the temperature induced magnetoelastic effect on Al͑x m͒/Metglas 2605S2 ͑20 m͒ / Al͑x m͒ trilayers ͑x = 0; 2.5; 5 and 20͒. It was found that the angle between the average sample magnetization and gamma ray direction ͑perpendicular to the sample plane͒ depends on the Al layer thickness. For temperatures smaller than 260 K, saturation of spin reorientation, which can be controlled by adjusting the Al thickness, was reached for Al thicknesses larger than and equal to 5 m. For a 20 m Al thickness, changes in the 57 Fe atom spin and charge densities have also been observed. A simple spin model has been proposed to describe qualitatively the spin reorientation effect as well as the influence of the Al thickness on the spin reorientation sensitivity.

Journal of Physics D: Applied Physics, 2008

Al coatings, with thickness (x) up to 20 µm, were deposited by dc sputtering on both sides of the... more Al coatings, with thickness (x) up to 20 µm, were deposited by dc sputtering on both sides of the Metglas 2605S2 precursor melt-spun ribbons. Spin reorientation, induced by the magnetoelastic effect, was clearly observed in the Al/Metglas 2605S2/Al trilayers by monitoring the 2 and 5 line intensities of the Mössbauer spectra obtained at different temperatures. The average spin orientation angles can be controlled by adjusting the Al thickness. A magneto-mechanical coefficient, which measures the rate of spin reorientation with respect to the temperature variation, was obtained and is found to be equal to −0.15 • K −1 and −0.28 • K −1 for x = 5 µm and 20 µm, respectively. Using a spin structure phenomenological model, in-plane native magnetic anisotropies ranging up to 3 kJ m −3 were estimated for the Metglas 2605S2 ribbons. Energy anisotropy values higher than 20 kJ m −3 are associated with inhomogeneities and defects from the sample preparation method and may correspond to about 10% of the ribbon volume.

Localization and magnetism of Fe replacing either Mn or Ni in the Ni 2 Mn 1.44 Sn 0.56 -type Heus... more Localization and magnetism of Fe replacing either Mn or Ni in the Ni 2 Mn 1.44 Sn 0.56 -type Heusler alloy have been systematically investigated using magnetization, scanning electron microscopy and Mössbauer spectroscopy. It has been shown that the addition of Fe either in Mn or in Ni sites reduces the fraction of the Mn-rich NiMnSn-type Heusler alloys that has short-range antiferromagnetic interactions; consequently it reduces the martensitic-austenitic transition temperature and increases the thermal hysteresis width due to an increase in atomic disorder caused by Fe replacements. The Fe atoms in Mn sites have two magnetic configurations with magnetic moments of 0.8µ B /Fe and 1.4µ B /Fe in the martensitic orthorhombic structure, while Fe in Ni sites have magnetic moments smaller than 0.1µ B /Fe. These results indicate that the Fe atoms are distinctly substituting either Mn or Ni and the decrease in the martensitic phase transition temperature for increasing Fe content can be mainly attributed to the Fe atoms in the Mn sites in both cases.