Mestrado em Química
URI Permanente para esta coleção
Nível: Mestrado Acadêmico
Ano de início: 2006
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=954
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- ItemSimulação por dinâmica molecular de flavonoides como inibidores da proteína principal do SARS-CoV-2(Universidade Federal do Espírito Santo, 2024-09-26) Lima, Ana Paula Loureiro; Gonçalves, Arlan da Silva; https://orcid.org/0000-0002-5965-3191; http://lattes.cnpq.br/4139608457982550; https://orcid.org/0009-0004-7226-538X; http://lattes.cnpq.br/6445846880137792 ; Silva Filho, Elói Alves da; https://orcid.org/0000-0002-9306-7882; http://lattes.cnpq.br/8259708288584235; Fernandes, Tácio Vinício Amorim; https://orcid.org/0000-0001-5881-9519; http://lattes.cnpq.br/9875296235929103The pandemic triggered by SARS-CoV-2 has instigated many efforts to identify effective therapies against COVID-19. In parallel, technological advances have provided an expanded platform for the exploration of bioactive compounds, among which flavonoids emerge as promising therapeutic agents, given their wealth of bioactive properties. Within the scope of this research, a Molecular Modelling approach was adopted to investigate the complex interactions between flavonoids and the key proteins of SARS-CoV-2, notably the main protease 3CLpro (Mpro) and the Spike protein, which are crucial for viral replication and cellular infection. Molecular dynamics simulations were used to evaluate the potential of these compounds as drug agents against COVID-19. Among the flavonoids studied, Amentoflavone, identified in plant species such as Ginkgo biloba, Hypericum perforatum and Passiflora, stood out for its remarkable efficacy in inhibiting the active site of viral proteins. In addition, 7‘’-O-Methylsciadopitysin showed the same RMSD result as Amentoflavone, with an MMPBSA energy of approximately -220 kJ/mol. Despite showing deviations from Lipinski's rule, implying potential limitations, these flavonoids stood out, suggesting possible adaptations that could mitigate such restrictions, thus extending their therapeutic viability and outlining promising prospects for the development of new pharmaceutical agents.
- ItemDesenvolvimento de uma metodologia eletroanalítica para detectar e quantificar ocratoxina A em amostras de café(Universidade Federal do Espírito Santo, 2025-06-05) Medeiros, Jane Schneider de; Oliveira, Jairo Pinto de; https://orcid.org/0000-0001-7595-1183; http://lattes.cnpq.br/2228283301316218; Ferreira, Rafael de Queiroz; http://lattes.cnpq.br/5053247764430323 ; https://orcid.org/0009-0002-6386-6090; http://lattes.cnpq.br/2714176584280814; Janegitz, Bruno Campos; https://orcid.org/0000-0001-9707-9795; http://lattes.cnpq.br/7746094938977989; Freitas, Marcos Benedito José Geraldo de; https://orcid.org/0000-0003-1521-774X; http://lattes.cnpq.br/3485939623614913Ochratoxin A (OTA) is a mycotoxin produced by fungi of the genera Aspergillus and Penicillium, frequently found in food products such as coffee, cereals, and spices. Given its toxicity and potential carcinogenicity, this study developed a sensitive and selective electroanalytical methodology for the detection and quantification of OTA in roasted and ground coffee. The method employed screen-printed electrodes composed of carbon black and graphite (SPE CB-G), modified in situ with cetyltrimethylammonium bromide (CTAB). The technique used was adsorptive stripping differential pulse voltammetry (DPAdSV), optimized through a central composite design (CCD). Raman spectroscopy characterization of the SPE CB-G confirmed the presence of graphite and carbon black, with a conductive surface suitable for electrochemical detection. The electroanalytical response of OTA was investigated using cyclic voltammetry (CV) under different electrolytes and pH ranges, demonstrating an irreversible oxidation process, with the anodic peak potential (Epa) shifting toward less positive values as the pH increased. The optimal electrochemical condition was achieved using phosphate buffer (PB) 0.2 mol L−1 (pH 7.0) with CTAB (80 µmol L−1), which favored OTA adsorption onto the electrode surface through electrostatic interactions with its anionic forms. Epulse, tpulse, tdep, and CTAB concentration parameters in both differential pulse voltammetry (DPV) and DPAdSV techniques were optimized via CCD to maximize the peak current (Ip). The optimized conditions provided excellent sensitivity and selectivity. The calibration curve in PB with CTAB showed linearity in the range of 10.10 to 242.29 ng mL−1 (R2 = 0.994), with a limit of detection (LOD) of 1.39 ng mL−1 and a limit of quantification (LOQ) of 4.20 ng mL−1. In the coffee matrix, LOD and LOQ were 2.70 ng mL−1 and 8.20 ng mL−1, respectively, also with R2 = 0.994. Recovery assays yielded values ranging from 94% to 110% in buffer with CTAB, wheat, and coffee, validating the method even in complex matrices. The analysis of typical coffee interferents revealed variations in OTA Ip due to competition for active sites on the SPE CB-G surface, with CTAB playing a critical role in minimizing these effects. The proposed methodology demonstrated high analytical performance, low cost, and suitability for routine analysis, meeting regulatory limits established by Anvisa and the European Union.
- ItemDesenvolvimento de materiais carbonosos porosos a partir de precursores naturais para captura de CO2(Universidade Federal do Espírito Santo, 2025-05-30) Garcia, Emily Fabre; Freitas, Jair Carlos Checon de; https://orcid.org/0000-0002-4474-2474; http://lattes.cnpq.br/3074997830683878; https://orcid.org/0009-0003-0730-9924; http://lattes.cnpq.br/5881029312815265; Chinelatto Júnior, Luiz Silvino; https://orcid.org/0000-0002-0974-0465; http://lattes.cnpq.br/8008284454162318; Emmerich, Francisco Guilherme; https://orcid.org/0000-0003-0470-2854; http://lattes.cnpq.br/0914292768585767Carbon dioxide (CO2) is one of the main greenhouse gases. The increase in anthropogenic activities results in higher CO2 emissions into the atmosphere, causing global warming. Carbon capture and storage are technologies capable of reducing atmospheric CO2 levels, contributing to mitigate the problems caused by global warming. Biochars have been widely investigated as adsorbents for CO2 capture due to their low cost and wide availability. However, research into CO2 capture followed by storage using biochars is still limited. Therefore, this work aimed to investigate the capture and storage of CO2 in physically activated biochars derived from coconut endocarp and chemically modified with calcium (Ca); for comparison, other biochars prepared from different precursors (such as coffee straw and babassu endocarp) and also modified with magnesium (Mg) were also investigated. The adsorption and carbonation performances were evaluated at different temperatures and humidity conditions. All the biochars analyzed were efficient at adsorbing CO2 at temperatures close to room temperature; the analyses carried out on the biochars derived from coconut endocarp showed that the adsorption capacity decreased progressively with increasing temperature. Among the samples derived from the endocarp of Cocos nucifera L. and babaçu coconut, and modified with Ca, the biochar with the lowest Ca content (3.5 %) had the highest specific surface area (577 m2/g) and the highest adsorption capacity (46.1 mg/g). The adsorption kinetics were evaluated using three kinetic models, with the Avrami model showing the best fit to the experimental data. Heat treatment at 510 ºC led to the formation of CaCO3 particles deposited throughout the porous structure of the biochar; the sample with the highest Ca content (23.9 %) and the lowest specific surface area (242 m2/g) showed the highest carbonation capacity. The carbonation of biochar modified with Ca was also affected by humidity, being significantly faster at room temperature in humid environments than in dry environments. The results of this study showed that Ca-modified coconut endocarp derived biocarbons are hybrid adsorbents capable of adsorbing and storing CO2 in the form of carbonates, and could serve as a sustainable alternative to help achieve the targets set by the Paris Agreement.
- ItemDesenvolvimento de eletrocatalisadores metálicos de baixo custo (Ni, Cu e Zn) para redução de CO2(Universidade Federal do Espírito Santo, 2025-01-30) Barcelos, Marcela Miranda; Ribeiro, Josimar; https://orcid.org/0000-0002-9544-1647; http://lattes.cnpq.br/1265145498501171; https://orcid.org/0009-0000-4612-0524; Rosa, Thalles Ramon; https://orcid.org/0000-0001-9913-5885; http://lattes.cnpq.br/2629035369494897; Luz, Priscilla Paiva; https://orcid.org/0000-0002-9460-546X; http://lattes.cnpq.br/3663470249824660Due to a series of environmental problems resulting from the burning of fossil fuels, it has led to an increase in CO2 emissions into the atmosphere, and it is clear that alternatives need to be considered. For example, electrochemical reduction of CO2 (RECO2) appears as a promising alternative to mitigate the impacts of high CO₂ emissions into the atmosphere. Therefore, the objective of this work is to investigate the metallic electrocatalysts of Cu, Ni and Zn for electrochemical reduction of CO2. In order to characterize morphological modifications of the metallic electrodes, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) techniques were used. The results of the XRD analyses revealed that the surface treatments did not alter the structure of the materials. The electrochemical polishing process of copper led to a mostly homogeneous morphology. On the other hand, the ultrasonic process in organic solvent allowed the increase of the roughness of the nickel and zinc electrodes, obtaining a heterogeneous morphology due to the surface reorganization of the materials. The electrochemical studies were performed using Linear Scanning Voltammetry (LSV), the potentiodynamic polarization technique and Electrochemical Impedance Spectroscopy (EIS). The EIS was performed at two different potentials: −0.4 V and −0.6 V vs. Ag/AgCl. The EIS results allowed the identification of substantial changes that occurred before and after the treatment of the electrodes. For the Cu and Ni electrodes, the EIS data indicate greater kinetics, i.e., lower charge transfer resistance. For the Zn electrode, the results indicate that there was competition in the hydrogen evolution reaction (HER). The LVS showed that the Cu and Ni electrodes showed a high current density for the electrochemical reduction reaction of CO2. It was observed that the uniform metallic copper surface acts as an inhibitor of the HER, resulting in a decrease in the overpotential and an increase in the current density for the CO2 reduction reactions. The nuclear magnetic resonance results obtained after the chronoamperometry experiments (constant potential of −2.0 V vs. Ag/AgCl in K2CO3 0.5 mol L–1 for 2 h) indicated the formation of some products from RECO2 such as: ethane, acetone and acetate. These results demonstrate the great potential of these electrocatalysts for the electrochemical reduction of CO2.
- ItemDesenvolvimento de biocompósito à base de amido de mandioca e fibras de eucalipto modificadas com nanopartículas de prata(Universidade Federal do Espírito Santo, 2025-03-19) Santos, Luisa Borges dos; Machado, Marta Albuquerque; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784; https://orcid.org/0009-0001-9653-5186; http://lattes.cnpq.br/3784351753717889; Silva, Marcelo Henrique Prado da; Silva Filho, Elói Alves daThis study describes the production of a thermoplastic starch-based (ATP) biocomposite reinforced with eucalyptus fibers (FE) chemically treated and modified with silver nanoparticles by thermocompression technique. The fibers were subjected to an alkaline process, followed by bleaching by hydrogen peroxide. To investigate the particle size effect of the reinforcing fibers, biocomposites containing 20 %(w/w) fibers in the particle size ranges of 75–250 𝜇m (ATP/FE75), 250–600 𝜇m (ATP/FE250) e 600–1800 𝜇m (ATP/FE600) were prepared. Then, the effect of the reinforcement load content (5, 10, 20 and 30 %w/w) was evaluated, maintaining the fixed particle size (600–1800 μm). Finally, silver nanoparticles were incorporated into the bleached fibers and the biocomposite (ATP/Ag@FE) containing the modified fibers was prepared in order to evaluate the influence of the modification. The treated fibers were analyzed by Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) to evaluate changes in the composition of the fibers and their crystal structure. All biocomposite samples formulated in this study were characterized by scanning light and electron microscopy, tensile tests, moisture absorption, and swelling. The sorption capacity of the biocomposites in petroleum/water emulsion was also evaluated. Micrographs revealed a higher matrix-fiber adhesion for the ATP/FE600 sample, which resulted in a 30% increase in maximum tensile strength, 63 % in tensile modulus and a 27 % reduction in elongation compared to the unreinforced sample. In contrast, tensile tests identified that a higher fraction of reinforcement fibers per volume of the biocomposite can impair adhesion, generating points of failure in the material. Regarding fiber content, the sample containing 10 %(w/w) showed an increase of 226 % in the maximum tensile strength and reduction of 63.9 % in elongation in relation to the sample without reinforcement. Meanwhile, samples containing 20 and 30 %(w/w) of fibers showed lower adhesion between the fiber and matrix, as evidenced by tensile tests and optical and scanning electron micrographs. In addition, surface modification with nanoparticles can improve the storage capacity of the material and can be applied to the treatment of oily emulsions, with a sorption capacity of the material of 53.8 %, and preserving the integrity of the material, slowing down the growth of microorganisms. The control of size and fraction, as well as the possibility of modifying the surface of the reinforcement material emerge as strategies to improve mechanical attributes and mitigate moisture/water absorption tendencies in starch-based biocomposites, contributing to sustainable and high-performance materials.