https://tedebc.ufma.br/jspui/handle/tede/1266 Ciência dos materiais é o campo da ciência de caráter interdisciplinar relativo ao estudo das propriedades dos materiais e a relação entre a sua estrutura em escalas atômicas ou moleculares com suas características macroscópicas, incorporando elementos da física e da química como as formas de caracterização e processamento. Thu, 14 May 2026 21:44:24 GMT 2026-05-14T21:44:24Z http://tede2.ufma.br:8080/jspui/retrieve/1336/loguinho.jpg https://tedebc.ufma.br/jspui/handle/tede/1266 https://tedebc.ufma.br/jspui/handle/tede/6890 Título: ESTUDO DE VIDROS BOROFOSFATOS DO SISTEMA B₂O₃–P₂O₅– CaF₂–Na₂O MODIFICADOS COM K₂O E Li₂O PARA APLICAÇÕES COMO BIOMATERIAIS REGENERATIVOS: Da síntese aos testes in vitro Autor: PEREIRA, Andrea Ferraz Silva Primeiro orientador: PEDROCHI, Franciana Abstract: The development of bioactive materials is guided by the continuous demand for effective solutions for tissue repair and regeneration, especially in cases of bone diseases, trauma, or infections. In this context, the incorporation of elements with physiological importance constitutes a promising strategy to adjust properties such as bioactivity, degradation rate, and cytocompatibility. This work aimed to synthesize and characterize borophosphate glasses with the composition 50B2O3–20P2O5–15CaF2–(15–x)Na2O–xMO (MO = K2O or Li2O, between 0– 15 mol%), using the melt-cooling method, to evaluate their potential as biomaterials. The study was developed in two stages. In the first, the progressive substitution of Na2O by K2O (0–15 mol%) was investigated, evaluating its effects on physical, structural, vibrational, and thermal properties, as well as on in vitro bioactivity behavior and cytocompatibility. In the second stage, the partial substitution of Na2O by Li2O (0–10 mol%) was analyzed, focusing on the physical, structural, thermal, mechanical, and bioactive properties of the glasses, as well as cytocompatibility and antibacterial activity. The samples were characterized by volumetric density, molar volume, oxygen packing density (OPD), powder X-ray diffraction (PXRD), FTIR spectroscopy, DTA, DSC, SEM-EDS, and Vickers microhardness (Hv). In vitro assays included bioactivity tests in SBF solution for 28 days, cell viability, and antibacterial activity. In the glass series containing K2O, structural expansion, depolymerization of the glass network, increased glass transition temperature (Tg), and high thermal stability were observed. Higher concentrations of K2O promoted increased reactivity in SBF and rapid formation of calcium phosphate and boric acid phases. Compositions containing both Na2O and K2O exhibited nonlinear behavior in the N4 fraction, indicating the occurrence of the mixed alkali effect (MAE). Furthermore, increasing K2O improved bioactive behavior, and the simultaneous presence of alkali oxides in the network favored cell viability. For the glass series containing Li2O, the occurrence of MAE was also observed in the physical properties, structural depolymerization, accompanied by a reduction in Tg. Increasing the Li2O concentration resulted in an increase in Vickers microhardness (Hv), indicating improved mechanical strength of the glasses. All compositions containing Li2O showed bioactivity, confirmed by PXRD and FTIR, and antibacterial activity. Finally, the results demonstrate that incorporating different alkali oxides in the structure of borophosphate glasses is a promising strategy for adjusting structural, mechanical, and bioactive properties, highlighting the potential of these glasses for applications as regenerative biomaterials. Instituição: Universidade Federal do Maranhão Tipo do documento: Tese; Trabalho sob Sigilo. O motivo do sigilo: O pedido de patente BR 10 2024 020751 3 encontra-se dentro dos 18 meses de sigilo no INPI (período contado a partir da data de depósito). Além disso, o sigilo é necessário para preservar a originalidade do artigo científico, oriundo da tese, que se encontra em elaboração para publicação em periódico indexado. Solicitação de patente: BR 10 2024 020751 3 DOI: https://doi.org/10.1016/j.ceramint.2025.12.242 Thu, 02 Apr 2026 00:00:00 GMT https://tedebc.ufma.br/jspui/handle/tede/6890 2026-04-02T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/6793 Título: Estudo teórico baseado na teoria do funcional da densidade das propriedades estruturais, eletrônicas e ópticas dos cristais de sarcosina e DL-alanina em função da pressão Autor: MOURA, Geanso Miranda de Primeiro orientador: ANDRADE FILHO, Tarciso Silva de Abstract: The study of the structural and electronic properties of amino acid crystals under different pressure conditions is highly relevant, as these materials have potential for technological applications. Understanding how pressure influences the characteristics of organic crystals can lead to significant advances in the development of new compounds and the optimization of industrial processes. Thus, this research not only advances theoretical knowledge about these systems but also paves the way for technological innovations. The methodology adopted for the computational calculations in this study is based on Density Functional Theory (DFT), using the Quantum ESPRESSO software. The Projector Augmented Wave (PAW) method was employed to perform the computational calculations, and the exchange- correlation components were described using the Perdew-Burke-Ernzerhof (PBE/GGA), PBE for solids (PBEsol/GGA), revised PBE (revPBE/GGA), and the non-local van der Waals correlation functional (vdW-DF). Additionally, the Grimme D3 dispersion term was applied in conjunction with all GGA functionals to correct for dispersion interactions. Geometry optimization was considered converged at 10−3 eV· Å−1 . In this research, the structural and electronic properties of sarcosine and DL-alanine crystals were investigated under extreme hydrostatic pressure conditions, with special attention to lattice parameters and hydrogen bond behavior. For sarcosine, discrete pressure points ranging from 0.0 to 3,7 GPa were used, while for DL-alanine the applied pressure ranged from 0,0 to 18 GPa. The computational results for the optimized lattice parameters a, b, and c and the volume of sarcosine at ambient pressure show deviations of less than 2% compared to experimental values reported in the literature. Regarding electronic properties, sarcosine exhibits a direct band gap at ambient pressure (along the Γ point). The calculated band gap was approximately 5.20 eV, indicating insulating behavior in this configuration. Under pressure, sarcosine displays anisotropic behavior and a theoretical bulk modulus B0 of about 6.98 GPa. Furthermore, the band gap of sarcosine does not decrease monotonically with pressure; it initially decreases from 5,20 eV to 4,90 eV up to approximately 1,4 GPa, then slightly increases, reaching 5,05 eV at 3,7 GPa. This non-linear behavior is interpreted as a result of competition between unit cell contraction and molecular rotation within the crystal. In terms of optical properties, the static dielectric constant showed values of 2,08 in the xx plane, 2,47 in the yy plane, and 2,17 in the zz plane, with the highest polarity in the yy plane, reinforcing the system’s anisotropic behavior. Strong absorption in the ultraviolet region indicates potential application as ultraviolet light polarizers. For DL-alanine, the computational results for the optimized lattice parameters and unit cell volume decrease continuously with increasing pressure, showing excellent agreement with available experimental data. Additionally, the b parameter decreased by approximately 14%, indicating greater flexibility of the crystal in this direction. Under pressure up to 18 GPa, DL-alanine exhibits anisotropic behavior and a theoretical bulk modulus B0 of about 8.48 GPa. Regarding the theoretical value of the crystalline dipole moment, the value obtained at ambient pressure was approximately 75 Debye, while above 15 GPa a sharp drop is observed, reaching approximately 38 Debye at 17,5 GPa. The voids are also drastically minimized, ranging from 84,76 Å3 at ambient pressure to values below 3,94 Å3 at pressures above 16,4 GPa - a reduction of approximately 95%. The results presented here are essential for a deeper understanding of the potential technological applications of sarcosine and DL-alanine in different scenarios, highlighting the relevance of theoretical studies dedicated to the investigation of crystalline systems under high- pressure conditions. This research deepens the understanding of intermolecular interactions, as well as the optical, structural, and electronic properties of organic crystals, establishing a solid foundation for future investigations in the field of materials science. Instituição: Universidade Federal do Maranhão Tipo do documento: Tese Mon, 30 Jun 2025 00:00:00 GMT https://tedebc.ufma.br/jspui/handle/tede/6793 2025-06-30T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/6788 Título: Propriedades estruturais, espectroscópicas e térmicas do sal de Tutton Rb2Co(SO4)2(H2O)6: uma abordagem experimental e teórica visando aplicações em dispositivos ópticos Autor: GOMES, Letícia Fonseca Primeiro orientador: OLIVEIRA NETO, João Gomes de Abstract: This work investigates the structural, spectroscopic, thermal, and optical properties of the Rb2Co(SO4)2(H2O)6 crystal, a Tutton salt with potential application in selective optical devices. The material was synthesized by slow solvent evaporation and characterized by powder X-ray diffraction (PXRD) with Rietveld refinement, Fourier- transform infrared (FT-IR) and Raman spectroscopies, thermogravimetric and differential scanning calorimetry (TG-DSC) analyses, and ultraviolet–visible–near infrared (UV-Vis-NIR) spectroscopy. The monoclinic crystal structure, belonging to the P21/a space group, was confirmed, with lattice parameters consistent with literature data. The analysis of intermolecular interactions, via Hirshfeld surfaces and calculations of crystal voids, revealed a dense lattice packing, predominantly governed by O···H/H···O hydrogen bonds, O···Co/Co···O coordination interactions, and Rb···O/O···Rb electrostatic interactions. Periodic calculations based on Density Functional Theory (DFT) indicated an electronic band gap of approximately 3.0 eV, mainly associated with the contributions of the Co2+ ion's d orbitals. Vibrational characterization allowed for the suitable assignment of Raman and FT-IR modes based on the structural units [Co(H2O)6] 2+, [SO4] 2- , and Rb+ . TG-DSC analyses revealed a dehydration event at approximately 111 °C, with the associated enthalpy for the dehydration process. The optical study showed absorption bands in the UV region associated with ligand-to-metal charge transfer transitions and bands in the Vis region attributed to d-d electronic transitions of the Co2+ ion, evidencing the Jahn-Teller effect. The observed absorption and transmittance windows indicate the material's intrinsic spectral selectivity, reinforcing its potential for applications in optical filters and selective photonic systems. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação Mon, 22 Dec 2025 00:00:00 GMT https://tedebc.ufma.br/jspui/handle/tede/6788 2025-12-22T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/6761 Título: Síntese, caracterização e estudos computacionais do fármaco etionamida e suas dispersões sólidas com ácido mandélico e ácido ftálico Autor: BEZERRA, Raychimam Douglas Santana Primeiro orientador: OLIVEIRA NETO, João Gomes de Abstract: This work presents the structural, spectroscopic, thermal, and computational investigation of different solid systems involving Ethionamide (ETH), a second-line drug widely used in the treatment of multidrug-resistant tuberculosis (MDR-TB), whose low solubility limits its bioavailability. Three distinct approaches were studied: the pure crystalline form of ETH, the coamorphous ETH–Mandelic Acid (MAD) system, and the pharmaceutical salt ETH–Phthalic Acid (PHT), with the aim of understanding and optimizing their physicochemical and biopharmaceutical properties. The compounds were obtained using the slow solvent evaporation method in different media (methanol and ethanol) and characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, thermal analyses, density functional theory (DFT) calculations, and Hirshfeld surface analyses. The crystalline form of ETH exhibited a monoclinic system (space group C1c1) stabilized mainly by H⋯H and H⋯S/S⋯H contacts, with dispersion energy accounting for approximately 60% of the total stabilization. Thermal analysis indicated stability up to 162 °C, and DFT calculations revealed a high electronic gap(HOMO–LUMO) (7.84–8.09 eV), supporting its low reactivity. The study of the coamorphous ETH–MAD system, prepared in 1:2 and 1:3 ratios, demonstrated the formation of an amorphous phase stabilized by hydrogen bonds between the NH2 groups of ETH and the C=O groups of MAD. The solid dispersions exhibited glass transition temperatures of 59 °C (1:2 ratio) and 61 °C (1:3 ratio), indicating good stability in the amorphous phase. In addition, the amorphous ETH–MAD (1:3) system remained stable in the amorphous state for up to 150 days. Dissolution tests showed a 3.58-fold increase in the solubility of ETH in the coamorphous system compared to the crystalline form, as well as controlled drug release when encapsulated in sodium alginate beads. The pharmaceutical salt ETH–PHT was obtained as a triclinic crystalline system (space group P1̅), stabilized by a strong N–H+···O− hydrogen bond (d = 1.742 Å). Thermal analyses revealed stability up to approximately 339 K, with endothermic events characteristic of melting and decomposition. Electronic analysis showed a direct band gap of 1.58 eV, indicating higher conductivity and enhanced pharmacological potential. Furthermore, periodic DFT calculations demonstrated the thermodynamic stability of the salt, with entropy increasing to 2192 kJ/mol·K and enthalpy to 957 kJ/mol at 1000 K, while the Gibbs free energy decreased, suggesting spontaneous phase reorganization. Dissolution studies under physiological pH (6.8; 37 °C) showed solubility 2.44 times greater than pure ETH (1.01 mg/mL versus 0.41 mg/mL). The results demonstrate that solid-state modifications of Ethionamide, through the formation of coamorphous systems and pharmaceutical salts, significantly enhance solubility, thermal stability, and controlled-release properties. Such advances reinforce the potential of these approaches as effective strategies for the development of optimized formulations aimed at treating multidrug-resistant tuberculosis. Instituição: Universidade Federal do Maranhão Tipo do documento: Tese Fri, 26 Dec 2025 00:00:00 GMT https://tedebc.ufma.br/jspui/handle/tede/6761 2025-12-26T00:00:00Z