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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- ItemUso de técnicas químicas avançadas para caracterização da identidade de méis de abelhas sem ferrão do Espírito Santo(Universidade Federal do Espírito Santo, 2025-03-13) Dias, Lucas Rodrigues de Oliveira; Ferreira, Rafael de Queiroz; http://lattes.cnpq.br/5053247764430323; Cunha Neto, Álvaro; https://orcid.org/0000-0002-1814-6214; http://lattes.cnpq.br/7448379486432052; http://lattes.cnpq.br/7422491599920966; Athayde, Geisamanda Pedrini Brandão; https://orcid.org/0000-0002-4315-0653; http://lattes.cnpq.br/8037324704189596; Morais, Verônica Santos de; https://orcid.org/0000-0002-7324-2057; http://lattes.cnpq.br/3680926664416715Stingless bee honey is considered a functional food due to the complex presence of chemical compounds with antioxidant properties. The chemical composition of honey is associated with several factors, such as the bee species, flowering, soil, and storage method. In this sense, this study investigated the chemical composition and antioxidant capacity of honey samples produced by Melipona species from different regions of the state of Espírito Santo - ES, Brazil. A comprehensive chemical characterization of each honey was conducted using advanced techniques, such as Fourier transform mid infrared spectroscopy (FT-MIR), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR), combined with chemometric tools. The flavonoid and total phenolic contents of the honey samples were determined using TPC (total phenolic compounds) and TFC (total flavonoid content) methods. Finally, the total antioxidant capacity (TAC) of each stingless bee honey sample was evaluated using FRAP (ferric reducing antioxidant power), DPPH (2,2-diphenyl-1-picrylhydrazyl), and CRAC (ceric reducing antioxidant capacity) assays. The PCA (principal component analysis) model based on FT-MIR signals showed the separation between the honey samples of Melipona capixaba and Melipona quadrifasciata. Volatile organic compounds (VOCs) were detected by GC-MS, and the most abundant classes were carboxylic acids, ketones, aldehydes and alcohols. The classification using the PCA model based on partial GC-MS chromatograms allowed the visualization of the clusters of honey samples from Melipona capixaba and Melipona quadrifasciata. Simple phenols such as p-cresol and allyl guaiacol were also identified in the honey. In addition, the TPC and TFC contents had selective correlations with TAC. A high Pearson correlation was observed between TPC and the CRAC antioxidant assay. Thus, chemometrics combined with chemical information obtained from the use of advanced FT-MIR, GC-MS, and NMR techniques; and from TFC and TPC, CRAC, FRAP, and DPPH methods are comprehensive tools that allow tracing an identity aligned with the quality of stingless bee honey from ES.
- ItemEfeito do campo magnético em um acoplado de grafeno e cobre : um estudo in silico(Universidade Federal do Espírito Santo, 2025-04-02) Vanny, Alberto Soares; Gonçalves, Arlan da Silva ; https://orcid.org/0000-0002-5965-3191; http://lattes.cnpq.br/4139608457982550; https://orcid.org/0009-0009-4751-9356; http://lattes.cnpq.br/5403932969047933; Silva Filho, Eloi Alves da; https://orcid.org/0000-0002-9306-7882; http://lattes.cnpq.br/8259708288584235; Scopel, Wanderlã Luis ; https://orcid.org/0000-0002-2091-8121; http://lattes.cnpq.br/1465127043013658; Oliveira, Osmair Vital de ; https://orcid.org/0000-0001-9463-2567; http://lattes.cnpq.br/3019137922691272; Cuya Guizado, Teobaldo Ricardo; https://orcid.org/0000-0002-3908-8076; http://lattes.cnpq.br/8371827192990091This dissertation is a theoretical study of the effect of a magnetic field on a coupled of graphene and copper, with the objective to separate the modeled nanostructures. Initially, 14 molecules of polycyclic aromatic hydrocarbons were evaluated as models to represent graphene nanostructures: benzene, naphthalene, anthracene, phenanthrene, pyrene, chrysene, benz[a]anthracene, tetracene, triphenylene, perylene, benzo[a]pyrene, benzo[e]pyrene, benzo[ghi]perylene, and coronene. Through computational analyses, properties such as energetic band gap, chemical potential (µ), chemical hardness (η), electronic occupation number (NOe), and theoretical Raman spectra were investigated. The results obtained were compared with experimental data from the literature, and coronene (Crn) was identified as the most suitable model to simulate graphene in theoretical studies. The Crn model was complexed with nanocrystals of copper (Cu) and nickel (Ni), metals commonly used in the production of graphene by the Chemical Vapor Deposition (CVD) method. The Crn/Cu coupled showed higher adsorption energy compared to the Crn/Ni coupled, indicating a weaker interaction between coronene and copper. Based on this result, the simulation of the magnetic field was performed only with the Crn/Cu coupled. Using the ORCA 5.0.4 software, computational calculations were performed with the B3LYP functional with the 6-31G* basis set, to simulate the application of magnetic fields with intensities varying from 0 T to 20 T. The results demonstrated that increasing the magnetic field in the Crn/Cu coupled leads to a significant increase in the adsorption energy between copper and graphene. This effect suggests that the application of magnetic fields can be a promising strategy to promote the controlled separation between graphene and copper, paving the way for the production of high-quality graphene monolayers with greater efficiency. This study contributes significantly to the understanding of the interaction between graphene and transition metals under the influence of magnetic fields. The results obtained provide valuable insights for the development of more efficient methods of separating graphene and copper, which can drive advances in the production of electronic devices and other graphene-based applications
- 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.