Principais Coleções do Repositório
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Methodological and ecological insights into methane-derived carbon assimilation by fish in tropical ecosystems
(Universidade Federal de Lavras, 2025-08-29) Urbano, Vinícius de Andrade; Pompeu, Paulo dos Santos; Carvalho, Débora Reis de; Leal, Cecília Gontijo; Santos, Rubens Manoel dos; Montag, Luciano Fogaça de Assis
Methane is a major greenhouse gas; in addition to human production, methane is widely produced in wetlands. However, the presence of fish in these ecosystems can contribute to reducing methane emissions. Before reaching the atmosphere, methane can be oxidized by methanotrophic bacteria and incorporated into the food chain. Stable carbon isotopes (δ13C) have been used to investigate the incorporation of methane-derived carbon in aquatic consumers, since aquatic invertebrates feed on methanotrophic bacteria and fish feed on these invertebrates. Therefore, the objective of this dissertation was: (i) to investigate the use of stable carbon isotopes to directly track the incorporation of methane-derived carbon in fish; (ii) to evaluate the incorporation of methane-derived carbon by apex fishes in four large Neotropical floodplains; (iii) to evaluate the incorporation of methane-derived carbon by fishes in a Neotropical reservoir and the role of non-native consumers in this dynamic; and (iv) investigate the influence of fish size, trophic guild, and seasonality on the assimilation of methane-derived carbon in floodplain lakes in a Neotropical region. The use of stable carbon isotopes can be considered an effective tool to directly estimate the incorporation of methane- derived carbon by fish, since methane has highly depleted δ13C values, allowing a clear distinction between this carbon source. Methane-derived carbon accounted for a significant proportion of fish biomass in different floodplains in South America, ranging from 5% to 15% of the carbon biomass. Higher levels of methane-derived carbon incorporation were observed in floodplains with higher methane production rates. Methane-derived carbon was also found to be an important energy source for fish in a Neotropical reservoir. However, non- native apex consumers pose a threat to this dynamic, as they feed primarily on the main assimilators of methane-derived carbon. Finally, the dynamics of methane-derived carbon uptake by fish appear to be strongly influenced by environmental characteristics, fish size, and seasonality, with no clear relationship to trophic guild. The rate of methane production and the availability of ecological links that transfer methane-derived carbon from methanotrophic bacteria to fish are the main drivers of its uptake in fisheries biomass. These findings also emphasize the importance of this carbon pathway in supporting fisheries biomass, a topic that has long been neglected. Furthermore, they highlight the important role of fish in incorporating methane-derived carbon into their biomass, ultimately contributing to the reduction of methane emissions, since methane oxidation and uptake in the food chain are inversely related to methane release. Therefore, these results highlight the importance of fisheries biomass conservation as a nature-based solution to natural methane emissions and methane emissions from artificial environments, such as reservoirs.
Cogumelos no Parque Nacional Itatiaia : diversidade e cultivo de espécies comestíveis
(Universidade Federal de Lavras, 2025-09-20) Oliveira, Akiiany Anderson Ribeiro de; Dias, Eustáquio Souza; Menolli Júnior, Nelson; Putzke, Jair
Edible mushrooms are an important source of medicinal and nutritional resources, with an estimated 2,000 species described in the literature. However, despite the rich biodiversity of the Atlantic Forest, knowledge about these mushrooms in Brazil is still limited. This study was conducted in Itatiaia National Park, Brazil's first conservation unit, which preserves a significant area of Atlantic Forest and potentially harbors species relevant to science. In total, 3,450 mushroom samples were collected from different altitude plots and times of year, with 916 types of mushrooms identified morphologically and molecularly, distributed in 9 orders, 30 families and 37 genera. The Basidiomycota phylum was predominant, especially the Agaricales order, which accounted for 58.18% of the samples identified. In addition, 29 isolates were isolated and kept in an in vitro collection, on Potato Dextrose Agar (BDA) media, with experimental cultivations, resulting in the identification of 14 possible edible species, including the cultivation of Irpex rosettiformis using the JunCao technique. The study combined traditional taxonomic methods with modern molecular techniques, providing a detailed overview of mushroom diversity in the region. In vitro mycological collections are valuable resources for future studies and practical applications in various scientific fields. The implications of this work are vast, as the knowledge generated can contribute to the conservation of biodiversity, the development of new food and therapeutic products, as well as more sustainable agricultural practices, underlining the importance of continued research into the mycobiota of the Atlantic Forest.
Nanofiltro de celulose bacteriana para remoção de contaminantes de águas residuárias
(Universidade Federal de Lavras, 2025-06-16) Ribeiro, Nayara Aparecida Santos; Silva, Cristina Ferreira; Brito, Ângela Dayana Barrera de; Abreu, Danilo José Machado de; Brito, Ângela Dayana Barrera de; Ribeiro, Luciana Silva
Water is a finite natural resource and essential for maintaining life on the planet. The increasing water scarcity has been aggravated by climate change, population growth, urbanization, and industrial and agricultural expansion. In addition, its exposure to various pollutants compromises its quality. Thus, to ensure water availability and quality, it is necessary to develop management strategies that encompass the recovery and reuse of contaminated wastewater that pose potential risks to human health and ecosystems. This study aimed to develop, characterize, and modify the bacterial cellulose membrane of Komagateibacter hansenii ATCC 23769 produced from agro-industrial coproducts, evaluating its efficiency in removing contaminants such as Escherichia coli and the herbicide atrazine. The cellulose membranes were modified through ex situ impregnation of chitosan and characterized regarding morphology, mechanical resistance, water-holding capacity, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Pure bacterial cellulose membranes and those modified with chitosan were subjected to nanofiltration assays in artificially contaminated water to evaluate the pollutant removal efficiency. The results demonstrated that the membranes reinforced with chitosan achieved better efficiency in removing contaminants, presenting greater bacterial retention and greater adsorption of the herbicide compared to pure bacterial cellulose. It is concluded that the membranes, especially when incorporated with chitosan, proved to be promising for the treatment of contaminated water.
Estudo da resistência mecânica e detecção de defeitos em estruturas de concreto a partir de funções de resposta em frequência e técnicas de aprendizado de máquina
(Universidade Federal de Lavras, 2025-12-12) Lima, Cássio Humberto; Santos, Fábio Lucio; Pereira, Rodrigo Allan; Velloso, Nara Silveira; Lima Júnior, Paulo de Oliveira; Abreu, Lucas Henrique Pedrozo; Borges, Paulo Roberto
The mechanical performance and durability of concrete are essential for ensuring the safety and longevity of structures used in civil and agricultural engineering. In response to the increasing incidence of pathological manifestations and the need for more precise monitoring methods, this study investigates the integrated application of experimental modal analysis and machine learning techniques to evaluate mechanical strength, identify defects, and compare the dynamic behavior of conventional concrete and bioconcrete incorporating macaúba endocarp (Acrocomia aculeata). Impact excitation tests were performed on specimens of different strength classes, recording frequency response functions (FRF) at two standard instrumentation positions to extract natural frequencies and damping ratios. The dynamic data were used in supervised machine learning models, particularly Artificial Neural Networks and Random Forest, to predict compressive strength and classify defect severity using an information- leakage-free pipeline. The results showed that dynamic properties—especially natural frequencies and damping—are sensitive to microstructural variations caused by both integrity loss and compositional changes in the concrete. The machine learning models exhibited robust performance in predicting strength and assessing integrity, highlighting the effectiveness of FRF as non-destructive predictors. The comparison between conventional concrete and bioconcrete revealed systematic dynamic differences, indicating that the partial replacement of coarse aggregate with macaúba endocarp influences dynamic stiffness without compromising structural behavior within the evaluated limits. This study therefore advances non-destructive evaluation techniques, demonstrates the feasibility of combining computational models with modal analysis, and proposes a methodological foundation for future applications in structural health monitoring and in the development of environmentally sustainable alternative materials.
O ensino de Filosofia na perspectiva freiriana
(Universidade Federal de Lavras, 2025-12-12) Santos, Fábio da Silva; Barbosa, Vanderlei; Betlisnk, Carlos; Laudares, Ellen Maira de Alcântara
The discipline of philosophy returns to basic education as a new field for pedagogical experimentation of philosophical thought. For a long time, philosophy remained confined to academic environments, depriving countless young people of the right to think critically, to sharpen their perspective on reality, to understand themselves and others with reason and sensitivity. Philosophical themes, problems, arguments, and concepts can become relevant to the lives of students, provided that their socio-historical-cultural experiences are problematized. In this vein, Paulo Freire's liberating pedagogy presents didactic-pedagogical principles such as freedom, awareness, problematization, and a critique of banking education, revitalizing the teaching of philosophy as a practice of freedom. The central research problem is the contribution of Paulo Freire's liberating pedagogy to the teaching and learning of philosophy, resulting in the production of two articles. Article I, “Approximations between Paulo Freire and Bell Hooks in the teaching of philosophy,” proposes a synthesis between Freire's liberating pedagogy and hooks' engaged pedagogy, culminating in the proposal of decolonial philosophy teaching. Article II, “The teaching of philosophy in the light of Paulo Freire's liberating pedagogy,” aims to propose a philosophy teaching approach that problematizes students' experiences in relation to philosophical thought. The research includes an educational product, “Didactic Sequence Notebook: Freirean Philosophical Culture Circle,” in which the concept of freedom in Freire, Augustine, Kant, and Sartre is problematized in dialogue with the unique, social, religious, ethical, and sometimes oppressive experiences of the students. The research methodology is based on a qualitative and bibliographical approach of an exploratory nature, with emphasis on the works “Pedagogy of the Oppressed” (1987) and “Pedagogy of Autonomy” (1996). The theoretical framework is based on a bibliographic review of books, articles, and dissertations by researchers in philosophy and education, such as Gallo (2007), Moacir Gadotti (2015), Brandão (2002), Kohan (2013), Ramos (2023), among others who dedicate themselves to proposing philosophical activity aligned with the problems, experiences, and needs of students. The results indicate that the teaching of philosophy as a practice of the philosophy of freedom cannot form emancipated citizens without embracing the social, racial, affective, political, and cultural demands of the students. It is concluded that philosophical teaching in dialogue with their experiences allows them to problematize their problems, thus developing the construction of philosophical thought. Teaching practice has the ethical, political, and pedagogical commitment to fight for a school that does not merely repeat mistakes, but proposes to reinvent itself