http://repositorio.ufc.br/handle/riufc/23890 Tue, 07 Apr 2026 13:15:24 GMT 2026-04-07T13:15:24Z http://repositorio.ufc.br/handle/riufc/84589 Título: Propriedades estruturais, eletrônicas e ópticas de cristais farmacêuticos monoclínicos: um estudo DFT do ácido salicílico, ácido acetilsalicílico, acetaminofeno e ibuprofeno Autor(es): Ferreira, Liciane Lourenço Abstract: The solid-state properties of pharmaceutical compounds play a critical role in their therapeutic efficacy, influencing solubility, bioavailability, and stability. In this study, we investigate the monoclinic crystalline forms of four widely used anti inflammatory drugs—salicylic acid, acetylsalicylic acid (aspirin), acetaminophen (paracetamol), and ibuprofen—using Density Functional Theory (DFT). Employing the PBE functional with Tkatchenko-Scheffler dispersion correction, we performed geometry optimizations of the unit cells, achieving lattice parameters within 1-2% of experimental values. Time-Dependent DFT (TD-DFT) calculations revealed molecular UV-Vis absorption spectra consistent with experimental data, elucidating key electronic transitions. Kohn-Sham band structure analyses using the HLE17 functional identified indirect band gaps ranging from 2.99 eV (salicylic acid) to 4.02 eV (ibuprofen), with near-direct transitions suggesting potential optical activity. For the acetylsalicylic acid crystal, the calculated optical absorption spectrum reproduces the main experimental features after a rigid energy shift, highlighting the effectiveness and limitations of the DFT-PBE+TS approach for describing its optical properties. Optical absorption and dielectric function calculations for light polarized along (100), (010), and (001) crystal directions highlighted anisotropic responses tied to crystal packing and hydrogen-bonding networks. These findings provide a comprehensive understanding of the interplay between molecular structure, crystal lattice, and optoelectronic properties, offering insights and providing a theoretical foundation for the rational design of pharmaceutical formulations with enhanced performance. Tipo: TCC Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/84589 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/84532 Título: Caracterização do ácido isoftálico (C8H6O4) por meio de espectroscopia Raman Autor(es): Guimarães, Emerson Mesquita Abstract: Isophthalic acid (C8H6O4) is an aromatic dicarboxylic compound of great industrial importance, especially in the production of polymers, resins, and plasticizers. This work aimed to characterize isophthalic acid crystals obtained by the slow solvent evaporation method. The crystalline structure was confirmed by single-crystal X-ray diffraction as monoclinic (space group P21/c). Thermal analysis (TG/DSC) revealed high stability up to approximately 300◦C, with a melting and decomposition event near 350◦C. Raman spectroscopy under ambient conditions, combined with density functional theory (DFT) calculations, allowed the identification of vibrational modes associated with the aromatic ring, carboxylic groups, and lattice vibrations. An excellent agreement was observed between experimental and theoretical spectra, confirming the reliability of the computational approach. Key modes were identified in the regions of 0–300 cm⁻¹ (lattice modes), 300–900 cm⁻¹ (ring deformations and breathing), 1200–1800 cm⁻¹ (C=O, C–O, and C–C stretches coupled to OH deformations), and 3000–3200 cm⁻¹ (C–H stretches). The results provide a comprehensive vibrational and thermal characterization of isophthalic acid, supporting its use in advanced material applications. Tipo: TCC Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/84532 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/84531 Título: Introdução às partículas de Majorana na teoria quântica de campos Autor(es): Oliveira, Elcy Gabrielle Xavier de Abstract: Majorana particles represent a special class of fermions that fundamentally differ from Dirac particles by being identical to their own antiparticles. This work addresses the mathematical formalism required to understand these objects within the framework of Quantum Field Theory, starting from a review of the Dirac equation and spinor algebra to the explicit construction of the Majorana field. The self-conjugation condition, ψ = ψc, imposes constraints that reduce the number of degrees of freedom and profoundly modify the structure of the theory, allowing mass terms that violate lepton number conservation. The physical implications of these mathematical properties are analyzed, with emphasis on neutrinos as the main experimental candidates. Neutrinoless double beta decay emerges as a decisive test of the Majorana nature, while the see-saw mechanism provides a natural explanation for the small observed masses of these particles. The results demonstrate how conceptual modifications in the description of fermions can lead to experimentally testable phenomenology. Tipo: TCC Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/84531 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/84516 Título: Topologia cósmica Autor(es): Chaves, Gustavo Leite Abstract: In this work we intend to discuss the topological and geometric structures of cosmological models. We begin with a review of differentiable manifolds, from the concept of topological manifolds to fundamental tools in Riemannian geometry. After that we present a classification of three-dimensional homogeneous spaces provided by Thurston, in 1982, focusing on constant curvature spaces and their respective fundamental polyhedra models. We also discuss the implications of the cosmological principle on the geometric structure of the FLRW model along with its divergences in terms of the anisotropy levels given by the CMB. Finally, we abandon the hypotheses responsible for the FLRW model in order to list the possible topologies of the spacial section of the spacetime. The importance of this work lies both on the rich structure behind cosmological models as well as on the value of a more rigorous treatment regarding our analysis on the topology of the Universe. Tipo: TCC Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/84516 2026-01-01T00:00:00Z