Vivian Machado de Menezes | Universidade Federal da Fronteira Sul (original) (raw)

Papers by Vivian Machado de Menezes

Cippus, Dec 7, 2017

Ensinar Fisica apenas com o livro didatico e um desafio cada vez maior para os professores devido... more Ensinar Fisica apenas com o livro didatico e um desafio cada vez maior para os professores devido a necessidade de relacionar o ensino cientifico com a realidade do aluno. A maioria dos professores nao utiliza experimentos didaticos em suas aulas, que tornam-se mecânicas e cansativas, pois sao restritas a resolucao de problemas e exercicios. Como alternativa para o ensino de Fisica, muitos docentes tem buscado introduzir atividades praticas, com o proposito de facilitar a compreensao dos fenomenos da natureza. Porem, tem-se constatado que a ausencia de laboratorios didaticos representa o principal motivo para estas praticas nao acontecerem. E sabido que as atividades praticas estimulam o interesse dos alunos, facilitando o aprendizado de Fisica e de suas aplicacoes no cotidiano. Neste contexto, este trabalho apresenta uma proposta de construcao de um dinamometro didatico de baixo custo, que aborda diferentes conceitos fisicos, tais como forca elastica, massa e peso, transformacao de unidades, medidas e erros, construcao de escalas e uso de papel milimetrado.

Revista Insignare Scientia, Nov 20, 2020

Resumo: Este trabalho teve como objetivo analisar os impactos dos projetos de pesquisa na aprendi... more Resumo: Este trabalho teve como objetivo analisar os impactos dos projetos de pesquisa na aprendizagem de Física dos estudantes do curso de Licenciatura Interdisciplinar em Educação do Campo: Ciências Naturais, Matemática e Ciências Agrárias, da Universidade Federal da Fronteira Sul, campus Laranjeiras do Sul. Primeiramente, foi realizado um levantamento bibliográfico acerca dos projetos de pesquisa, contextualizando com a disciplina/ensino de Física. Posteriormente, foi realizada uma entrevista estruturada com os estudantes que participaram dos projetos de pesquisa vinculados ao curso de Educação do Campo, com o intuito de saber a opinião dos mesmos acerca da contribuição destes projetos no processo de aprendizagem de Física e também na sua formação profissional. De acordo com a pesquisa exploratória realizada, percebe-se que os projetos contribuem de forma positiva para os acadêmicos, tanto no viés da aprendizagem de Física quanto na formação profissional proposta pelo curso, pois eles representam uma maneira de associar a teoria à prática, possibilitando novas formas de ensino e aprendizado, por meio das atividades desenvolvidas.

Revista Insignare Scientia, Jun 20, 2021

Feira de Ciências da Cantu na UFFS: comunicação científica para a comunidade regional, escolar e ... more Feira de Ciências da Cantu na UFFS: comunicação científica para a comunidade regional, escolar e acadêmica Feira de Ciências da Cantu na UFFS: scientific communication for the regional, school and academic community Feira de Ciências da Cantu na UFFS: comunicación científica para la comunidad regional, escolar y académica

Regionem: Revista Interdisciplinar em Desenvolvimento Sustentável

The purpose of this work was to develop a numerical simulation methodology using a free software ... more The purpose of this work was to develop a numerical simulation methodology using a free software capable of predicting the behavior of oxygen in multilayer polymeric systems to optimize packaging configurations with a greater barrier to O2. The Laplace Transform method was used to solve partial differential equations, with numerical inversion by the Stehfest algorithm together with the Gauss-Sidel method. It was possible to simulate the oxygen concentration profile in packaging systems containing two or three materials in the configuration. For some systems, the increase in the simulation time caused a numerical fluctuation at the material interface, especially if oxygen diffused from a material with greater diffusivity to one with lower diffusivity. The numerically simulated oxygen concentration profile can be associated with results from the literature, experimentally validated. The results showed to be promising for application in diffusion problems of multilayer systems, and the...

Carbon nanostructures, 2015

ABSTRACT In the last decade, carbon nanostructures have been exhaustively studied mainly associat... more ABSTRACT In the last decade, carbon nanostructures have been exhaustively studied mainly associated with their application in biosensors and drug delivery systems. In this context, the present chapter introduces several studies combining amino acids and pharmaceutical drugs with carbon nanostructures such as graphene, carbon nanotubes and fullerene. More specifically, the biomolecules under focus are the amino acid cysteine and the pharmaceutical drugs nimesulide, meloxicam and zidovudine. These molecules can be considered models for different chemical interactions or adsorptions with carbon nanostructures. The adsorptions analysed suggest possible applications such as biosensors or drug delivery depending on the use of particular pristine or functionalised carbon nanomaterials.

The experimental discovery of graphene with one atom thick allows the production of ribbons, call... more The experimental discovery of graphene with one atom thick allows the production of ribbons, called graphene nanoribbons. While these materials share properties with other carbon based materials, such as carbon nanotubes and graphene, other effects arise due to their width and the edge geometries. In this context, this work aims to investigate the zigzag nanoribbons electronic and magnetic properties dependence on the impurity position by ab intio calculations. A chemical sensitivity of the ribbon properties is demonstrated, noting different behaviors of the electronic properties with magnetic Mn impurities and nonmagnetic Ti impurities doping. It is also shown that the nanoribbons edges are the energetically favorable sites, independent of the impurity type.

ABSTRACT In this work is analyzed, through simulations based on first principles density function... more ABSTRACT In this work is analyzed, through simulations based on first principles density functional theory (DFT), single-wall carbon nanotubes interacting with metals such as aluminum, iron, manganese and titanium, via of adsorption and substitutional doping. The structural and electronic properties of the systems for each of the dopants used are evaluated. Since these materials exhibit unique characteristics, such as presenting high resistance and flexibility, can be applied from the electronic to the pharmacy. The results show that it is possible to modify the spin polarization of the systems, and there is a change of character of conduction of the carbon nanotube, which is of great importance to implementation of these elements in spintronics and the development of new materials and nanotechnology.

Physical Chemistry Chemical Physics, 2012

In this paper, the structural, electronic and magnetic properties of carbon nanotubes doped with ... more In this paper, the structural, electronic and magnetic properties of carbon nanotubes doped with Al, Fe, Mn and Ti atoms interacting with vitamin C molecules are studied through first principles simulations based on the density functional theory. The charge transfers are obtained from the vitamins into the tubes for adsorption and substitutional doping cases. The highest binding energies of vitamin C molecules are calculated for the Al substitutional and Ti adsorbed cases, with values of about 1.20 and 3.26 eV, respectively. The results demonstrated that, depending on doping, the spin polarizations and the conductance characters of the systems can change, which could be relevant to improve the molecule adsorption on carbon nanostructures.

Disciplinarum Scientia | Naturais e Tecnológicas, 2011

... 1 Trabalho de Iniciação Científica - PROBIC/FAPERGS. 2 Acadêmicas do Curso de Física Médica -... more ... 1 Trabalho de Iniciação Científica - PROBIC/FAPERGS. 2 Acadêmicas do Curso de Física Médica - UNIFRA. 3 Orientadora - UNIFRA. ISSN 1981-2841 Page 2. Disc. Scientia. ... Na verdade, o orbital não tem significado físico, pois é uma proba-bilidade matemática. ...

Journal of Biomedical Nanotechnology, Apr 1, 2012

The energetic and structural properties of fullerenes, carbon nanotubes and graphene interacting ... more The energetic and structural properties of fullerenes, carbon nanotubes and graphene interacting with vitamins A, B3 and C were studied by first principles simulations. These vitamins, which have antioxidant activities, give support to the cellular metabolism, have biochemical, therapeutic and cosmetic functions, and when combined with carbon nanostructures may have their chemical instability controlled. In this work, the results illustrate that the strongest interaction is between vitamin A and graphene. The binding energies found for the interactions between carbon nanostructures and these vitamins range from 0.10 to 0.93 eV. For all the configurations studied, a physisorption regime is observed without significant changes in the chemical and physical properties of the adsorbed vitamins, which is relevant for a drug delivery system.

Physica Status Solidi B-basic Solid State Physics, Nov 12, 2013

The structural and electronic properties of end-CCN pristine and functionalized by carboxyl, amin... more The structural and electronic properties of end-CCN pristine and functionalized by carboxyl, amine, amide, and hydroxyl chemical groups under the action of electric fields are investigated through first-principles simulations based on the density functional theory.

Materials Research Society Symposium Proceedings, 2008

We have investigated the electronic and transport properties of zigzag Ni-adsorbed graphene nanor... more We have investigated the electronic and transport properties of zigzag Ni-adsorbed graphene nanoribbons ͑Ni/GNRs͒ using ab initio calculations. We find that the Ni adatoms lying along the edge of zigzag GNRs represent the energetically most stable configuration, with an energy difference of approximately 0.3 eV when compared to the adsorption in the middle of the ribbon. The carbon atoms at the ribbon edges still present nonzero magnetic moments as in the pristine GNR even though there is a quenching by a factor of almost five in the value of the local magnetic moments at the C atoms bonded to the Ni. This quenching decays relatively fast and at approximately 9 Å from the Ni adsorption site the magnetic moments have already values close to the pristine ribbon. At the opposite edge and at the central carbon atoms the changes in the magnetic moments are negligible. The energetic preference for the antiparallel alignment between the magnetization at the opposite edges of the ribbon is still maintained upon Ni adsorption. We find many Ni d-related states within an energy window of 1 eV above and below the Fermi energy, which gives rise to a spin-dependent charge transport. These results suggest the possibility of manufacturing spin devices based on GNRs doped with Ni atoms.

Regionem: Revista Interdisciplinar em Desenvolvimento Sustentável, 2023

REVISTA BRASILEIRA DE PESQUISA EM ALIMENTOS, 2022

Microelectronics Journal, 2009

Electronic and structural properties of carbon nanotubes interacting with vitamins C and B3 radic... more Electronic and structural properties of carbon nanotubes interacting with vitamins C and B3 radicals are analyzed through the density functional theory. The radical adsorptions result in modifications on the structural and electronic properties of the original carbon nanotubes. The strong adsorptions resulting from the combination of the carbon nanotubes with ascorbic acid and nicotinamide allow the manipulation of the resulting systems in a stable way. These results are extremely relevant in order to identify the potential applications of functionalized carbon nanotubes as drug delivery systems or molecule sensors.

Journal of Plastic Film & Sheeting, 2022

Many food products are sensitive to oxygen which can promote rancidity, aerobic microorganism gro... more Many food products are sensitive to oxygen which can promote rancidity, aerobic microorganism growth, browning, vitamin degradation, flavor loss, and other undesirable reactions. Active packaging concepts have been successfully applied to delay these deteriorative phenomena. In particular, oxygen scavengers help limit O2 ingress into packaging thus extending product shelf-life and thereby reducing food waste. Besides oxygen barrier polymers, other composite materials have been developed to reduce the overall O2 permeability into the package by adding oxygen scavengers or barrier fillers into the packaging structures. Typical thermoplastic food packaging barrier properties are summarized, including commercially available ones, and reported in the patent literature. Furthermore, various mathematical models have been developed to predict the oxygen transport behavior in active packaging to simulate oxygen transport in polymeric and composite materials. Such models are helpful to provid...

Journal of Biomedical Nanotechnology, 2012

Um dos maiores desafios encontrados no ensino de Fisica e Ciencias consiste na conexao entre o co... more Um dos maiores desafios encontrados no ensino de Fisica e Ciencias consiste na conexao entre o conhecimento adquirido pelos alunos e o mundo cotidiano. E cada vez maior a preocupacao dos professores em introduzir experimentos nas disciplinas cientificas, na tentativa de facilitar a compreensao dos fenomenos da natureza. Mas muitas escolas brasileiras nao possuem laboratorios e tampouco recursos financeiros para a realizacao de atividades experimentais, e muitas vezes os proprios docentes nao apresentam o preparo necessario e nem dispoem de tempo para o desenvolvimento de tais atividades. Diante das dificuldades encontradas, e feita a proposta da elaboracao e validacao de experimentos que se utilizem de materiais de baixo custo, reciclaveis ou ate mesmo sucata, para a futura utilizacao destes em sala de aula, oficinas e outras atividades de ensino de Fisica. Os experimentos incluem conceitos e aplicacoes de Fisica Geral, e contam com roteiros e materiais didaticos de apoio elaborados...