https://repositorio.ufu.br/handle/123456789/5095 Fri, 11 Sep 2026 17:12:36 GMT 2026-09-11T17:12:36Z https://repositorio.ufu.br:443/retrieve/5d840d16-5110-4322-b9bc-9a21d4f14ecf/IQ-removebg-preview.png https://repositorio.ufu.br/handle/123456789/5095 https://repositorio.ufu.br/handle/123456789/50149 Title: Equidade digital na educação pós-pandemia: mediação pedagógica com plataformas digitais para o ensino de eletroquímica em contextos educacionais diversos Abstract: Electrochemistry presents notorious and well-documented teaching and learning difficulties, which were substantially aggravated by the implementation of emergency remote teaching. This context demanded greater student autonomy and required educators to develop effective didactic alternatives for conceptual mediation at a distance, thereby deepening long-standing obstacles. This qualitative investigation aimed to evaluate the impacts of implementing digital educational resources—an offline application and a website titled Electrochemistry in Everyday Life—on the teaching and learning process. The goal was to overcome historical obstacles exacerbated by the remote context and promote equity in access to meaningful learning across distinct educational settings (public, private, and rural) in Itumbiara, Goiás, Brazil. The study unfolded sequentially in five methodological stages: first, a systematic literature review was conducted to map obstacles in electrochemistry education and analyze the effectiveness of active methodologies; subsequently, the challenges of emergency remote teaching in Science/Chemistry were investigated through the perceptions of teachers and students from three educational contexts, which were contrasted with institutional documents; third, after development and classroom implementation, the digital resources underwent rigorous validation by teachers and students (focusing on usability, user experience, and learning principles), resulting in an improved version and demonstrating feasibility even in contexts with limited technological infrastructure; finally, the impacts of these resources on student participation and cognitive performance were evaluated using pre- and post-intervention questionnaires across the three contexts. Initial diagnostic results confirmed the severity of the situation, with 63% of students rating their remote Chemistry classes negatively and citing a lack of concentration at home as the primary hindrance. These challenges were most pronounced in the Rural School, which exhibited a significant lack of teacher training and technical support. Following the intervention with the digital tools, quantitative data showed significant progress, noting a considerable improvement in conceptual understanding—exemplified by the Public School achieving approximately 50% correct answers in a Moodle Quiz—indicating the overcoming of cognitive obstacles. Qualitatively, students reported increased motivation and a clearer grasp of abstract concepts, attributing this progress to the resources' effective contextualization of content with everyday phenomena. Nevertheless, difficulties associated with prior curricular gaps persisted in the Rural School, despite these students showing notable engagement in practical activities. In conclusion, the complexity of challenges inherent to remote teaching, which manifest heterogeneously, tends to intensify pre-existing educational disparities. However, the developed digital resources, designed with a contextualized approach and subjected to a rigorous validation process, represent promising pedagogical strategies for mitigating learning gaps in electrochemistry. These tools demonstrated potential to catalyze student engagement, foster autonomy, and outline feasible pathways for promoting educational equity in diverse contexts, particularly in scenarios with infrastructural limitations. The research's legacy points toward transforming an emergency experience into lasting progress through continuous investment in evidence-based digital resources and teacher training for critical implementation. Wed, 12 Aug 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50149 2026-08-12T00:00:00Z https://repositorio.ufu.br/handle/123456789/50087 Title: Redução eletrocatalítica de CO2 utilizando um novo complexo de Re(I) contendo o ligante (z)-n-metil-2-(6-oxo-1,10-fenantrolin-5 (6H)-ilideno) hidrazinacarbotiamida Abstract: Tricarbonyl rhenium(I) complexes, commonly represented as fac-[Re(CO)₃(NN)Cl], where NN denotes bipyridine-derived ligands, have been extensively investigated as homogeneous catalysts for CO₂ reduction. This study aimed to synthesize a new complex, fac-[Re(CO)₃(Phmt)Cl], where Phmt = (Z)-N-methyl-2-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)hydrazinecarbothioamide, and to investigate its electrochemical behavior as a potential electrocatalyst for CO₂ reduction. The synthesis of fac-[Re(CO)₃(Phmt)Cl] was carried out by first preparing the Phmt ligand under reflux in toluene, followed by reaction with the metal precursor [Re(CO)₅Cl] under reflux to afford the desired complex. The product was characterized by Fourier-transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance (¹H NMR) spectroscopy to confirm its molecular structure. The ¹H NMR spectrum displayed signals predominantly between 7 and 15 ppm, with the two most downfield resonances assigned to the amine hydrogen atoms, while the remaining signals corresponded to the aromatic protons. The FTIR spectrum provided further structural confirmation, exhibiting characteristic bands assigned to ν(N–H) (≈3268 cm⁻¹), ν(C≡O) (≈2027, 1900, and 1890 cm⁻¹), and ν(Re–N) (≈260 cm⁻¹), indicating the presence of amine groups, the facial geometry of the tricarbonyl complex, and metal–ligand coordination, respectively. The electrochemical properties were investigated by cyclic voltammetry (CV) in anhydrous dimethylformamide (DMF) under argon and CO₂ atmospheres. Under argon, the complex exhibited an irreversible oxidation peak corresponding to the Re(I)/Re(II) redox process. In the cathodic region, three irreversible reduction peaks were observed at −1.0, −1.6, and −2.1 V vs. Fc⁺/Fc, consistent with values reported for structurally related compounds. Under a CO₂ atmosphere, a significant catalytic current enhancement was observed (Ic/Ip = 2.41), with the first reduction peak shifting to −1.93 V vs. Fc⁺/Fc. These electrochemical results indicate that the synthesized complex is a promising candidate for the electrocatalytic reduction of CO₂ to CO. Wed, 29 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50087 2026-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/50001 Title: Desenvolvimento de plataformas analíticas portáteis baseados em línguas optoeletrônicas e narizes eletrônicos para análise discriminativa Abstract: Artificial olfactory systems have been widely employed for the detection and discrimination of chemical compounds in various analytical applications, including quality control, environmental monitoring, diagnosis, and food analysis. However, their performance remains limited by high instrumental cost and constraints in the generation and processing of chemical information. In colorimetric systems, limitations in signal acquisition may reduce response resolution and hinder the discrimination of complex samples. In this context, the development of low-cost and more efficient approaches for chemical information extraction remains highly relevant in Analytical Chemistry. This thesis aimed to develop and evaluate two artificial olfactory systems based on a portable electronic nose and a paper-based colorimetric sensor array with multichannel signal acquisition, integrated with chemometric tools for chemical pattern recognition. The low-cost electronic nose was constructed using semiconductor sensors coupled to an open-source microcontroller platform, while the colorimetric system employed a paper-based sensor array combined with an AS7341 spectral sensor. In both cases, optimization of experimental conditions led to more stable and reproducible responses. The electronic nose enabled the separation of volatile organic compounds, whereas the colorimetric sensor array allowed the discrimination of acid–base systems and eleven types of food samples. Compared with RGB-based approaches, the multichannel system exhibited higher resolution, sensitivity, and robustness against experimental interferences. PCA and HCA confirmed the presence of multivariate chemical signatures capable of discriminating complex systems. Overall, the results demonstrate that both approaches are promising low-cost analytical tools for screening and quality control. Future work includes extension to different matrices and integration with machine learning methods to improve classification and predictive performance Mon, 27 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50001 2026-07-27T00:00:00Z https://repositorio.ufu.br/handle/123456789/49735 Title: Cremes hidratantes faciais anti-idade: uma revisão dos mecanismos de ação dos diferentes ativos disponíveis no mercado Abstract: Skin aging is a complex and inevitable biological process driven by intrinsic factors, such as genetics and metabolism, and extrinsic factors, with exposure to ultraviolet radiation (UV), pollution, and lifestyle standing out as the primary accelerators of extracellular matrix degradation. This study conducted a literature review on the process of cutaneous senescence and analyzed the efficacy of active ingredient classes, mechanisms of action, and formulations used to prevent and treat its signs. Skin physiology reveals that the depletion of structural components, such as collagen, elastin, and glycosaminoglycans, combined with the collapse of the calcium ion gradient, underlies the development of wrinkles and skin laxity. Analysis of the active ingredients demonstrated that the efficacy of these cosmeceuticals depends on crucial variables, such as active ingredient concentration, vehicle formulation, and chemical stability in the presence of oxidizing species. Anti-aging actives, including humectants, retinoids, alpha-hydroxy acids, peptides, and antioxidants, function through hydration, cell signaling, epidermal renewal, and free radical neutralization. However, many formulations require the combination of photoprotection and encapsulation technologies to maximize delivery and skin tolerability. Given the growing market driven by contemporary aesthetic pressures, the pursuit of anti-aging treatments should be grounded in a scientific understanding of their chemical mechanisms and conscious consumer choices, avoiding the unnecessary or inappropriate use of potent products while promoting skin health and consumer safety. Thu, 30 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49735 2026-07-30T00:00:00Z