https://ri.ufs.br/jspui/handle/riufs/2471 Mon, 27 Apr 2026 06:53:34 GMT 2026-04-27T06:53:34Z http://ri.ufs.br:80/retrieve/0e61cc54-f198-47a5-8d64-77c5609fcdb0/PPGQ.jpg https://ri.ufs.br/jspui/handle/riufs/2471 https://ri.ufs.br/jspui/handle/riufs/24224 Título: Eletrocatalisador bifuncional baseado em material carbonáceo para geração de hidrogênio e oxigênio de baixo carbono Autor(es): Santos, Marcos Vinícius Quirino dos Abstract: The high cost, scarcity, and limited durability of noble-metal-based electrocatalysts, such as platinum, iridium, and rhodium, have driven the search for alternative materials that are abundant, sustainable, and economically viable for use as catalysts in water electrolysis. In this context, biochar derived from plant residues has emerged as a promising carbon-based material for the development of efficient and environmentally friendly electrocatalysts. This dissertation reports the development of an electrocatalyst based on biochar derived from the aquatic plant Marsilea minuta (BMQ), applied to the hydrogen evolution reaction (HER) in acidic medium and to the oxygen evolution reaction (OER) in alkaline medium. The biochar was prepared by pyrolysis at 500 °C under an inert nitrogen atmosphere and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results revealed an amorphous structure with a porous surface and the presence of oxygen- and nitrogen-containing functional groups, which act as active sites for electrocatalytic reactions. Electrochemical tests using a glassy carbon electrode modified with the material demonstrated significant activity for both HER and OER, exhibiting low overpotentials required to reach a current density of 10 mA cm⁻² and Tafel slopes consistent with favorable reaction kinetics. Electrochemical stability was confirmed by chronopotentiometry, highlighting the potential of BMQ as a bifunctional electrocatalyst with low carbon emissions. These results indicate that biochar derived from Marsilea minuta is a promising and sustainable alternative for application in water electrolysis systems, contributing to the advancement of low carbon hydrogen and oxygen production technologies. Thu, 14 Aug 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/24224 2025-08-14T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/22473 Título: Uso de métodos in silico para a identificação de alcaloides com atividade em múltiplos alvos no tratamento da doença de Alzheimer Autor(es): Santos, Yria Jaine Andrade Abstract: Alzheimer's disease is a prevalent and progressive neurodegenerative disease and the leading cause of dementia worldwide. Despite its widespread incidence, available treatments are scarce. Currently, the search for new therapeutic options has focused on the cholinergic and glutamatergic pathways. In silico approaches are essential to identify promising substances, reducing research costs and time. The aim of this study is to identify alkaloids with potential activity through virtual screening using QSAR and docking models. QSAR models were developed from banks of structures tested on these targets. 2D and 3D descriptors were calculated and evaluated for multicollinearity and correlation. Models were developed with different algorithms, undergoing internal and external validation, and used to screen alkaloid banks. The NMDA, NAChR and AChE target banks contain 91, 100 and 389 chemical structures, respectively, for which 7974 descriptors were calculated. The crystallographic structures coded 5EWM, 3SQ6 and 4EY7 were used for docking, and the models developed were used to evaluate the behavior of the alkaloids selected for the respective sites and the interactions carried out. For the NMDA model, 8 descriptors were selected, with the best result being the MLP model with R2TEST=0.654 and Q2=0.533. For the NAChR model, 6 descriptors were used, with the MLP model showing R2TESTE=0.861 and Q2=0.672. Finally, for the AChE model, 7 descriptors were selected, with the best MLP model showing R2TEST=0.872 and Q2=0.605. It was observed that in all the models developed, one or more descriptors were selected that emphasized the importance of nitrogen compounds for target activity. This characteristic is observed in endogenous ligands and drugs known to act on them. After validation, the models were used to screen the alkaloid bank, evaluating compounds with the highest predicted activity according to the target's activity in the disease. It was noted that the predicted activity values were in line with the experimental values of active substances in the targets. In addition, many of these substances have reported neuroprotective activity, or belong to classes of alkaloids commonly associated with this activity. Substances already tested on the target were also identified, such as boldine selected for AChE. The results of the screening were submitted to docking models, and those with the best performance and favorable interactions with the amino acids that make up the active site were selected. This study demonstrated the efficiency of using in silico methods to identify alkaloids with potential activity against the targets addressed. The compounds identified represent important options for the development of new therapeutic options for Alzheimer's disease. Mon, 17 Feb 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/22473 2025-02-17T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/21848 Título: Desenvolvimento e aplicação do LUMPAC 2.0 no estudo da luminescência em compostos de Eu 3+ Autor(es): Oliveira, Willyan Farias Abstract: The first version of LUMPAC (LUMinescence PACkage) was released by the Pople Laboratory (UFS) in 2014, with the objective of being a user-friendly program for studying luminescent properties, particularly for Eu3+ compounds. The implementation of new tools for the theoretical investigation of trivalent lanthanide ion (Ln3+) properties motivated the development of version 2.0 of LUMPAC in the present work. Among the new features, the following stand out: the possibility of performing multiple parallel calculations, the study of additional energy transfer (ET) channels, the calculation of ET rates for ligand-Tb3+systems, and the rendering of molecular orbitals for the characterization of excited states. During the development process, several features in LUMPAC 2.0 facilitated the modeling of ET in Eu3+ complexes, and these features were validated through various studies published by our research group. LUMPAC 2.0 is based on a protocol proposed by de Sá and collaborators for the theoretical study of ET in Ln3+ compounds. However, alternative protocols have been proposed recently: Carneiro Neto and collaborators considered a greater number of ET channels; Georgieva and collaborators included the contribution of excited state geometry relaxation of the compound; and Beltrán-Leiva and collaborators employed fluorescence and phosphorescence calculations to interpret ligand to metal ET. Two Eu3+ complexes were studied using these methodologies with the support of LUMPAC 2.0 in a complementary manner. It was observed that the methodology proposed by Beltrán-Leiva and collaborators provided intraligand rates useful for the protocols by de Sá and collaborators and Carneiro Neto and collaborators to achieve better theoretical quantum yields, although improvements are still needed. Wed, 19 Feb 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/21848 2025-02-19T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/21819 Título: Estudo teórico da aplicação da MOF-74-mg no carreamento de fármacos Autor(es): Rocha, Jeanynne Leite da Abstract: The search for new types of treatment and new drugs to combat cancer, one of the diseases that most affect Brazilians, is increasing, because the drugs used in chemotherapy are dangerous and are present in the specificity. For this reason, they are being generated, since the MOFs for a drug release have a controlled speed, with a possibility of effective delivery in the desired active site. In this context, the present work has the application of a computational method for the evaluation of metallic nets in the controlled release of the drugs ibuprofen (IBU), 5-fluoracil (5-FLU) and cisplatin (CIS), used for the treatment of Cancer. The computationally quantitative translated the RASPA and MOPAC2016 programs. Improvement in adsorption of drugs with MOF-74-Mg when compared with the experimental and theoretical data found in the literature. Mg-MOF-74 interacting with Mg-MOF-74, with varying binding energies and greater energy-binding amplitude of 36.93 kcal / mol with greater potential for slower and less favorable release 6,30 kcal / mol with potential for faster drug release. Other drug-MOF-74-Mg interactions are being evaluated and are being evidenced with the deeper investigations, which have already been initiated. Wed, 19 Feb 2020 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/21819 2020-02-19T00:00:00Z