Principais Coleções do Repositório
Submissões Recentes
Computational tool to evaluate the efficency of hydrogen in internal combustion engines
(Universidade Federal de Lavras, 2025-03-20) Rincon, Alvaro Ferney Algarra; Alvarez, Carlos Eduardo Castilla; Ensinas, Adriano Viana; Rodriguez, Christian Jeremi Coronado
Behavioral studies on the efficiency of a hydrogen engine are important, as they are part of a global initiative to decarbonize the automotive sector, and this technological route for the use of hydrogen is promising within recent energy transition studies. In this sense, the exploration of new technological development routes around production, commercialization and use of hydrogen for the state of Minas Gerais and for Brazil has been proposed through various government initiatives in recent years. For this reason, this work has developed a computational tool based on a zero-dimensional mathematical model capable of predicting the efficiency of a spark ignition engine when using hydrogen as fuel. The simplicity of the model offers a quick view of the operation and thermodynamics of the engine, which reduces computational effort and produces results that represent the real behavior of hydrogen combustion. This focus helps in the study of combustion and in making decisions about the economic viability of using hydrogen in internal combustion engines. To do this, the compression, combustion and expansion processes in the Otto cycle were mathematically modeled to represent the combustion behavior of the air-hydrogen blend inside the engine cylinder, using code written in MATLAB. The mathematical model was validated with experimental data taken from the research engine bench and those reported in the literature in relation to the pressure curve for the different engines and operating conditions evaluated, and the efficiency produced by the engine under these conditions was estimated. A graphical interface was generated in AppDesigner for the computational tool, making it easier for the user to develop the behavioral and operational study of a hydrogen engine. The results obtained with the computational tool show that the estimated pressure and efficiency values are in good agreement with those found in the literature in all the cases evaluated. The maximum error when comparing the pressure curve was 1.32% for an engine with a speed of 3300 RPM. In addition, the minimum fit of the mathematical model to the experimental data was 86%, which represents a good alternative for estimating the thermal efficiency value.
Soil health and microbial diversity in early restoration sites affected by tailings from the Fundão dam failure
(Universidade Federal de Lavras, 2026-01-31) Silva, Letícia Coelho Vaz; Carneiro, Marco Aurélio Carbone; Silva, Aline Oliveira; Dunfield, Kari E.; Carvalho, Teotônio Soares de; Botelho, Soraya Alvarenga; Paulino, Helder Barbosa; Cordeiro, Meire Aparecida Silvestrini
The failure of the Fundão dam in 2015 resulted in the deposition of large volumes of iron mining tailings over soils in marginal sites throughout the Doce River basin in Mariana, Minas Gerais, severely compromising their physical, chemical, and biological properties and posing major challenges to environmental recovery. In this context, this study evaluated soil recovery in revegetated sites affected by iron mining tailings from the Fundão dam, integrating soil health, microbial community analysis, and functional prediction based on molecular data. Soil recovery was investigated through the application of a Soil Health Index (SHI), developed from physical, chemical, and biological indicators in sites with 3, 4, and 5 years of revegetation following tailings deposition, compared with a native vegetation reference site, using composite soil samples collected at a depth of 0–10 cm. The results demonstrated that revegetation promoted progressive improvements in soil health, including increases in available water content, soil organic carbon, carbon stocks, K and S availability, as well as enhanced microbial and enzymatic activity. Functions related to plant growth support, carbon storage, and habitat provision showed faster recovery, whereas nutrient cycling remained the most limited function, indicating non-linear recovery trajectories constrained by the tailings-derived substrate. The response of soil microbial communities to revegetation was evaluated using high-throughput sequencing of the 16S rRNA and ITS2 regions and microbial functional potential prediction with PICRUSt2, revealing that although revegetation promoted shifts in taxonomic composition and the emergence of microbial groups associated with plant–microorganism interactions, revegetated sites remained distinct from the reference site, indicating persistent limitations in soil biogeochemical complexity and the need for longer recovery periods. Functional predictions indicated constraints in carbon-related metabolic pathways and oxidative processes, consistent with the low organic matter availability in the tailings, while also revealing early signs of a return toward the functional state of the microbiota and its contribution to ecosystem services. Overall, the results demonstrate that revegetation promotes initial structural and functional improvements in soil, but that microbially mediated processes recover more slowly, highlighting the relevance of integrating soil health indices with microbiome-based approaches and functional prediction to diagnose limitations, monitor recovery, and guide restoration strategies in tropical soils impacted by mining tailings.
Seleção fenotípica de progênies de arroz de terras altas auxiliada por marcadores moleculares
(Universidade Federal de Lavras, 2026-01-29) Lago, Karen Eduarda do; Botelho, Flávia Barbosa Silva; Castro, Adriano Pereira de; Berchembrock, Yasmin Vasques; Simão, Janine Magalhães Guedes; Borba, Tereza Cristina de Oliveira; Pereira, Welison Andrade
Rice (Oryza sativa L.) is the dietary staple for approximately 2.5 billion people. In Brazil, there is a concerted effort to intensify upland rice cultivation as a sustainable alternative, given its reduced water requirements and lower greenhouse gas emissions. Within this context, breeding programs aim to develop early-maturing, high-yielding genotypes for integration into agricultural production systems, utilizing genetic diversity as a primary source for selection. Thus, this study aimed to evaluate the agronomic performance and genetic diversity of progenies from the Family Yield Trial (FYT) during the 2023/24 growing season, verified through molecular analysis using SSR (Simple Sequence Repeats) markers. A total of 169 progenies were evaluated using a 13x13 partially balanced lattice design with two replicates across three locations: Lavras (MG), Santo Antônio de Goiás (GO), and Sinop (MT). The traits evaluated included days to flowering (DTF), plant height (cm), and grain yield (kg ha⁻¹). Data were subjected to a joint analysis of variance via mixed models (REML/BLUP) using R software. Molecular characterization was performed with 24 microsatellite (SSR) markers analyzed by capillary electrophoresis. Of the 24 markers, 21 were successfully amplified, detecting 133 alleles (ranging from 2 to 13 alleles per locus). Cluster analyses identified 21 clusters for both phenotypic and molecular data. Twenty phenotypically superior progenies were identified; when contrasted with molecular clusters, these were distributed across nine distinct genetic groups. It is concluded that there is considerable genetic diversity to be exploited and that simultaneous selection based on agronomic performance and molecular divergence allows for the identification of promising progenies, thereby mitigating the narrowing of the program's genetic base.
Polímeros para retardo de germinação com a finalidade de sincronismo de florescimento entre plantas de milho
(Universidade Federal de Lavras, 2026-02-02) Oliveira, Jéssica Batista Ribeiro e; Santos, Heloisa Oliveira dos; Ferreira, Guilherme Max Dias; Carvalho, Everson Reis; Pereira, Wilson Vicente Souza; Brandão Junior, Delacyr da Silva
Corn is a crop of great national and international importance, and the production of hybrids depends on flowering synchronization, often achieved at a higher cost. To overcome this challenge, several strategies have been studied, including the use of polymeric coatings on seeds. These coatings regulate water absorption and germination, increasing uniformity. Biodegradable polymers are more sustainable but have limitations, while synthetic polymers can delay germination and favor synchronization, making them strategic for the production of hybrid seeds. The objective was to evaluate the efficiency of biopolymeric and acrylic resin formulations, the latter at different doses and concentrations, in coating corn seeds to delay germination and favor flowering synchronization. The first experiment was divided into two phases. In the first phase, the effect of the coating on corn seeds, a commercial single hybrid and line 64 of the Corn Genetic Improvement Program, DAG-UFLA, was evaluated using 9 biopolymeric formulations through an emergence test. In the second phase, the effect of 22 biopolymeric formulations on seed coating of line 64 was investigated. The dose used was 1.1 L of the formulation per 100 kg⁻¹. In the second experiment, the effect of coating seeds of line 64 with acrylic resin (RA) at concentrations of 50%, 60%, 80%, and 100% resin was evaluated, applied at doses of 3 L and 6 L per 100 kg of seeds. Uncoated seeds were used as a control. The water content, emergence speed (ES), time to emergence of 50% of seedlings (T50), first count, and percentage of emerged seedlings at the final count were determined, obtained four and seven days after sowing, respectively. Coating with the biopolymeric formulations did not alter the water content and showed genotype-dependent responses. Formulations 1 and 2 showed potential for delaying emergence without compromising the final stand. However, coating with RA alters the moisture content of the seeds of line 64 and accelerates seedling emergence, not being suitable for delaying emergence, although it favors initial development and the establishment of the final stand.
O plano de recomposição das aprendizagens como estratégia de intervenção pedagógica em escolas estaduais da SRE de Campo Belo – Minas Gerais
(Universidade Federal de Lavras, 2026-03-03) Pimenta, Ulisses Carolino; Cabral, Giovanna Rodrigues; Lima, Carla da Conceição de; Borges, Regilson Maciel
Brazil and planet Earth as a whole experienced, during the year 2020, one of the greatest pandemics ever known to humanity: acute respiratory syndrome, caused by the coronavirus - Covid 19. This syndrome left several sequelae in humans and, regarding education, caused a considerable gap in student learning. To address these gaps caused by the pandemic period, the State Department of Education of Minas Gerais – SEE-MG – implemented, in 2023, the Central Pedagogical Management Center – NGPC – and the Regional Pedagogical Management Center – NGPR, the latter in each of the 47 Regional Education Superintendencies – SRE. The objective of creating these Nuclei was to collaborate with state schools in the development of the Learning Recovery Plan – PRA. This Plan should contain the skills not worked on during the pandemic period. Thus, the present Dissertation has the general objective of investigating the effects of the implementation of the NGPC and NGPR, responsible for the development of the PRA together with the pedagogical team of the state schools of the SRE–Campo Belo, based on the results obtained in the evaluations of the Minas Gerais System of Evaluation and Equity in Public Education – SIMAVE, focusing on the 9th grade of Elementary School, in the period from 2018 to 2024. As specific objectives, the following can be highlighted: 1. To describe the pedagogical intervention programs of the state network of Minas Gerais in the last ten years; 2. To present the creation of the NGPC and NGPR and the implementation of the PRA with the school pedagogical team (principal, vice principal, basic education specialist, and teachers), within Minas Gerais, based on guiding documents and specific legislation; 3. To compare the results of SIMAVE from the schools under the jurisdiction of SRE-Campo Belo, focusing on the 9th grade of Elementary School, in the period from 2018 to 2024; 4. To prepare a document (PowerPoint presentation) containing the results obtained in this research work and present it to the NGPR, the team of educational analysts of the SRE, and basic education specialists from the schools involved, through a meeting in the format of a Pedagogical Workshop. It is a fact that, by offering various strategies of pedagogical intervention, SEE-MG made efforts to address these learning gaps, but can it be said that this strategy (specifically the PRA) had its success proven, based on student learning? This study, developed from both qualitative and quantitative perspectives, was conducted based on the collection of data from the results on the SIMAVE Portal. It was based on theories such as those of Tardif and Lessard (2005) on teaching work as a profession of human interactions, Lück (2009), who deals with the dimensions of school management, and is based on the studies of Libâneo, Oliveira, and Toschi (2012) to support discussions on public policies, school structure, and organization. The research has academic and practical relevance, with the potential to inform educational policies and pedagogical practices, as well as to contribute to the initial and continuing training of educators. The hypothesis is that all the effort expended by SEE-MG had a positive effect on the learning of students in Minas Gerais. However, through the results, it became evident that the public policy implemented, by itself, was not sufficient to positively change the learning of 9th-grade students during the period studied. As a result, the Educational Product, in PowerPoint format, was prepared to be presented to the school's pedagogical teams, to the analysts of SRE Campo Belo, and also to NGPR, as a way to stimulate reflection among those involved regarding the results obtained.