Mestrado em Física
URI Permanente para esta coleção
Nível: Mestrado Acadêmico
Ano de início: 1992
Conceito atual na CAPES: 4
Ato normativo: Parecer CES/CNE nº 487/2018, homologado pela Port. MEC 609, publicado no DOU em 18/03/2019.
Periodicidade de seleção: Semestral
Área(s) de concentração: Física
Url do curso: https://fisica.ufes.br/pt-br/pos-graduacao/PPGFis/detalhes-do-curso?id=1508
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- ItemCaracterização de produtos de complexação furazolidona/β-ciclodextrina(Universidade Federal do Espírito Santo, 2025-03-31) Robran, Lukas Eller; Miguel Ângelo Schettino Junior; https://orcid.org/0000-0002-7903-9041; http://lattes.cnpq.br/3366999814625339; Freitas, Jair Carlos Checon de; https://orcid.org/0000-0002-4474-2474; https://orcid.org/0009-0002-3683-9767; Lopes, Thierry Ramos; Villanova, Janaina Cecília Oliveira; Scopel, Wanderlã LuisCyclodextrins are cyclic oligosaccharides used in the formation of inclusion complexes. For these, hydrophobic molecules are included in the cavity of cyclodextrins, as a pharmacotechnical strategy to get around issues such as low water solubility, and low active pharmaceutical ingredient (API) stability. This characteristic is of extreme importance for the pharmaceutical industry, due to the improvement of drug bioavailability. Furazolidone is an antimicrobial and antiprotozoal API that has been withdrawn from use in humans in Brazil thanks to its toxicity. However, the API has been the subject of studies in the attempt to reposition its use in humans and animals, including as a leshmanicidal agent, contributing to fight this neglected disease endemic in low wage populations. Unfortunately, its insolubility in water causes low bioavailability. This problem motivates the study of its complexation with cyclodextrins, something not yet widely studied for this drug. Works of this kind are relevant due to being in line with Sustainable Development Goal 3 from the United Nations 2030 Agenda. In this study, different mixtures of β-cyclodextrin and furazolidone were prepared by kneading, dyalisis followed by freeze-drying, stove drying and physical mixture. The prepared mixtures were characterized by X-ray diffraction (XRD), thermal analysis and solid state nuclear magnetic resonance (NMR) to check for changes in physical, chemical or strucutral features caused by different preparation procedures. Some evidence for these modifications was observed, such as furazolidone melting peak reduction and variations of cristallinity of both compounds. The lattice parameters obtained with X-ray diffraction showed no significant changes for the different mixtures, and the diffraction peaks have noticeable changes in intensity. Differential thermal analysis showed the amount of crystalline furazolidone melting was reduced in kneaded and stove-dried mixtures. Solid-state 1H and 13C NMR analysis revealed reduction in 1H spin-lattice relaxation times (T1) and 1H spin-lattice relaxation times in the rotating frame (T1ρ). However those values were still significantly distinct for β-ciclodextrin and furazolidone, indicating possible immiscibility of the these components at the molecular level and that an inclusion complex was not formed.
- ItemOndas gravitacionais em modelos cosmológicos: isotrópicos e anisotrópicos(Universidade Federal do Espírito Santo, 2025-04-22) Viana, Luar Samir Oliveira; Gonçalves, Vitorino de Borba; https://orcid.org/0000-0002-8570-9750; http://lattes.cnpq.br/4992784379693871; Oliveira Neto, Gil de; Alvarenga, Flavio Gimenes; Rodrigues, Davi CabralGravitational waves of cosmological origin are currently one of the most promising channels for probing the early universe. While homogeneous and isotropic cosmological models are extensively employed to describe the gravitational backgrounds through which gravitational radiation propagates, anisotropic models can account for certain phenomena not predicted by the standard model, such as specific anomalies observed in the cosmic microwave background (CMB). Therefore, in this dissertation, we analyze the theoretical formulation of gravitational waves within both the isotropic FLRW model and the anisotropic Bianchi type I model. To this end, we initially adopt the gauge-dependent classical approach of cosmological perturbation theory. The issue of gauge fixing is given special attention, and we find that the commonly used synchronous, transverse, and traceless gauges, which are widely employed in the isotropic case, are no longer mutually compatible in the anisotropic scenario, even though the longitudinal components of gravitational waves have no physical significance, as demonstrated throughout this work. Consequently, the two irreducible, decoupled polarization modes typical of gravitational waves can no longer be obtained solely through a gauge analysis, and the resulting wave equations are coupled. In light of this, we employ the gauge-invariant formalism for a comprehensive physical analysis and interpretation, from which we derive the two polarization modes, for all possible wave vector configuration, and obtain analytical solutions to the wave equations for various particular cases. Ultimately, we believe this work provides a relevant analysis of the gauge issue, given the existing discrepancies in the specialized literature.
- ItemKinks em AdS2: configurações BPS em teorias de campo escalar(Universidade Federal do Espírito Santo, 2025-03-25) Battisti, Geórgia Sant’Anna; Sotkov, Galen Mihaylov; https://orcid.org/0000-0002-7276-016X; http://lattes.cnpq.br/6372536076880230; https://orcid.org/0000-0003-4887-0913; ; Martins, Gabriel Luchini; https://orcid.org/0000-0001-6627-3034; http://lattes.cnpq.br/3344738411070832; Gonçalves, Sergio Vitorino de Borba; https://orcid.org/0000-0002-8570-9750; http://lattes.cnpq.br/4992784379693871; Silva, Ulysses Camara; https://orcid.org/0000-0002-0409-5284; http://lattes.cnpq.br/6782992379960964In this work, we investigate the properties and behavior of BPS kinks in the context of curved spacetimes, particularly in two-dimensional Anti-de Sitter space (AdS2). BPS kinks are topological solitons in 1+1 dimensions that connect different vacua of a potential and minimize the energy of the system, satisfying simplified first-order equations. We examine how the curvature of AdS space influences the properties and asymptotic behavior of BPS kinks, the stability of these solutions, and the condition of minimum energy. The work is divided into chapters that cover the fundamentals of solitons in Minkowski spacetime, the construction of BPS solutions in AdS, and applications to the ϕ4 model
- ItemDa física da luz à modelagem estelar: uma análise dos processos físicos e das equações de estrutura estelar(Universidade Federal do Espírito Santo, 2024-12-12) Barcellos, Vinícius Alexandre Gomes; Velten, Hermano Endlich Schneider; https://orcid.org/0000-0002-5155-7998; Fabris, Júlio Cesar; Eraso, Gustavo Andres GuerreroThis work addresses fundamental aspects of modern astrophysics, focusing on three main areas: the theory of radiation, the equations of stellar structure, and stellar modeling. The first part discusses the interaction between light and matter, highlighting the formulation of Planck’s Law, as well as the applications of photometry and spectroscopy in determining stellar parameters. In the second part, the fundamental equations governing stellar structure, derived from fluid mechanics, are presented, along with their relation to hydrostatic equilibrium and energy transport. The final part addresses stellar modeling, introducing the Lane-Emden equation and its modifications in the relativistic context and in modified gravity theories, with an emphasis on the beyond-Horndeski theory. These theories aim to expand the frontier of knowledge in astrophysics and cosmology, seeking to eliminate the need for "bizarre" components in the universe.
- ItemDessalinização da água e seletividade iônica em membranas de grafeno kagome(Universidade Federal do Espírito Santo, 2024-12-20) Ferreira, Rhayla Mendes; Souza, Fábio Arthur Leão de; Pansini, Fernando Néspoli Nassar; https://orcid.org/0000-0001-8984-686X; Albuquerque Filho, Marcelo Fabio Costa; Scopel, Wanderlã LuisPopulation growth in major urban centers and the high demand from industries increase the need for potable water. However, approximately 97% of the water available on our planet is found in seas and oceans. Additionally, the quantity and quality of accessible freshwater are directly affected by global warming, making the search for new techniques and materials to obtain potable water essential. This dissertation investigates the potential of Kagome graphene (KG), 2-triangulene, and 3-triangulene membranes in desalination processes and ion selectivity. Molecular dynamics (MD) simulations with KG membranes in saline solutions (0.5 M and 1.0 M) and uniform electric fields ranging from 0 to 0.5263 V ·nm−1 were conducted to assess system viability. It was observed that the 2-triangulene membrane allowed the natural passage of water molecules but retained ions in the absence of an electric field, indicating promising behavior for desalination processes. Below 0.0877 V ·nm−1, 2-triangulene exhibited greater selectivity for Na+, while above 0.0877 V ·nm−1, it retained more ions than the 3-triangulene membrane, even at higher salt concentrations. Both membranes displayed non-ohmic behavior. Although complete desalination was not achieved, the ion selectivity and performance of the 2-triangulene membrane open new possibilities for optimizing membrane design and adapting this technology to various industrial contexts, contributing to advances in water purification technologies.