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.
Effects of limestone application on soil physical, chemical, and biological properties and coffee yield
(Universidade Federal de Lavras, 2025-07-09) Severo, Gabriele Medeiros Hermógenes; Moreira, Silvino Guimarães; Castanheira, Dalyse Toledo; Melo, Leônidas Carrijo Azevedo; Peixoto, Devison Souza; Alves, José Maria Arcanjo
Liming is essential for soil acidity in tropical regions, affecting chemical, physical, and biological soil properties with potential impacts on coffee crop productivity. This set of studies evaluated the effects of increasing lime rates (0 to 24 Mg ha-1 ), applied either on the surface or subsoiling, on fertility, structure, microbial activity, and yield in coffee-cultivated Oxisols under field conditions in Minas Gerais, Brazil. The first two studies were conducted from 2019 to 2023 on plantations at the Samambaia (Site 1) and Frade (Site 2) farms, where increasing doses of limestone were applied superficially to coffee plantations in 2018. The third study was carried out on coffee plantations located in the UFLA coffee sector. In the first study, multivariate analyses identified that doses of 3 and 6 Mg ha-1 applied superficially significantly increased soil pH values, as well as Ca, Mg, K and SO4 2- contents and soil organic matter, with an increase in productivity with the application of 6 Mg ha-1 . The second study pointed to specific effects of liming on soil structure, such as an increase in water-dispersed clay and microporosity, without significantly altering its structure in general. Coffee yield varied between sites (Sites 1 and 2), with a quadratic response and maximum yield estimated with an application of 12 Mg ha-1 on Site 1. In the third study, which compared the effect of surfaceapplied limestone doses, with or without subsoiling, it was observed that liming increased arylsulfatase activity and microbial respiration, regardless of the application method (with or without subsoiling), although it did not significantly affect microbial biomass carbon or other enzymes analyzed. Coffee tree productivity did not change significantly in the short term. In general, the results indicated that surface liming is capable of promoting important improvements in the chemical and biological properties of the soil, with localized effects on the physical structure and responses in productivity, which varies according to the environment, reinforcing the importance of specific management strategies in consolidated coffee systems. Keywords: Coffea arabica L.; microbial activity; soil fertility and structure; tropical soils.
Citologia e histologia no diagnóstico de afecções dermatológicas em cães de abrigos de Lavras - MG
(Universidade Federal de Lavras, 2026-03-25) Ferreira, Daiane da Cruz; Raymundo, Djeison Lutier; Sonne, Luciana; Varaschin, Mary Suzan; Raymundo, Djeison Lutier
Dermatological conditions in shelter dogs represent a complex challenge to animal welfare and One Health, given the high stocking density and the risk of zoonoses. This study aimed to characterize the dermatopathological profile of shelter dogs in Lavras-MG, integrating two studies: a retrospective survey and a systematic prospective approach to evaluate the use of cytopathology and histopathology as diagnostic tools. The retrospective survey analyzed nodular lesion records (162 dogs; 168 diagnoses; 2014-2024) from the Veterinary Pathology Sector (SPV/UFLA) and non-nodular records (n=50; 2019-2024) from the Clinical Pathology Sector (SPC/UFLA) of the Federal University of Lavras. There was a higher frequency of neoplastic processes (50.59%; 85/168) in nodular lesions, notably Transmissible Venereal Tumor (TVT) (14.11%; 12/85) and mast cell tumor (10.58%; 9/85), while a high number of negative results for ectoparasites and dermatophytes (74.00%; 37/50) was identified in nonnodular conditions. In the prospective study, conducted from November 2024 to May 2025, the screening of 260 dogs revealed a prevalence of 30.76% (80/260) of animals with active dermatological lesions, totaling 90 sampled conditions. In prospective nodular conditions, an inversion of the epidemiological profile was observed due to the mitigation of referral bias, with follicular cysts consolidating as the most frequent individual finding (24.44%; 11/45), followed by lipoma (15.55%; 7/45). In prospective non-nodular conditions, there was a prevalence of bacterial and parasitic inflammatory processes, with 48.78% (20/41) of samples testing negative for agents, consolidating cytopathology as a mandatory step in the diagnosis by exclusion for allergic, endocrine, or immune-mediated dermatopathies. Fine-needle aspiration (FNA) was the most used technique for nodular collection (73.33%; 33/45), with a diagnostic yield of 84.44% (38/45). Passive demand reveals a bias toward high-impact clinical conditions, such as TVT and mast cell tumor, while the high negativity rate (74%) in nonnodular cases reflects both the masking of complex etiologies and the intrinsic difficulty in detecting agents in superficial or chronic presentations. Conversely, active surveillance exposes a silent burden of benign lesions (cysts and lipomas) and parasites of One Health relevance, such as sarcoptic mange. In this context, cytopathology establishes itself as a tool for oncological screening and diagnostic exclusion for allergic, immune-mediated, or endocrine dermatopathies, while histopathology remains the gold standard for definitive diagnosis and prognostic determinations. Keywords: cytopathology; skin diseases; veterinary diagnosis; screening; shelter medicine.
Sensitation profile of occupational allergic diseases and quality of life in veterinary medicine students
(Universidade Federal de Lavras, 2026-03-05) Menezes, Tathiana Tavares; Pereira, Luciano José; Peconick, Ana Paula; Costa, Monique Gomes Salles Tiburcio; Segundo, Gesmar Rodrigues Silva; Silva, Grazielle Caroline da
Veterinarians are among the occupational groups most affected by allergic respiratory diseases due to early and prolonged exposure to animal allergens during training and professional practice. However, epidemiological data on sensitization profiles, risk factors, and protective factors among veterinary medicine students are still limited. Veterinary medicine students present a substantial burden of sensitization to allergens, particularly to cats, mainly influenced by environmental and early childhood factors. This study aimed to evaluate the prevalence of allergic individuals among university students, especially veterinary medicine and animal science students, as well as to assess the incidence of allergic symptoms (longitudinally) according to course progression and its relationship with quality of life, through the application of questionnaires on asthma and rhinitis symptoms, quality of life, and risk factors for the development of respiratory allergies. In addition to the questionnaires, sensitization to dog and cat hair was assessed through a prick test. To meet the objectives, the first chapter addressed the prevalence of allergies in Veterinary Medicine and Animal Science students at UFLA and UNILAVRAS, compared to students in courses without occupational contact with animals; it longitudinally evaluated sensitization to dog and cat dander, using the skin prick test, in incoming students and after 1 year of academic activities, listing possible risk and protective factors related to allergic rhinitis and asthma. The fluctuation of allergic symptoms and their relationship with the degree of occupational exposure to animal dander was also analyzed. Early childhood exposure can promote immunological tolerance, while late or intermittent exposure—combined with genetic predisposition and highly sanitized environments—can favor allergic sensitization, leading to the development of asthma and rhinitis. Allergic sensitization to dog and cat dander and the development of asthma and rhinitis are multifactorial processes influenced by genetic, environmental, and exposure-related factors. In the second chapter, the persistence or not of allergic respiratory symptoms after occupational exposure during one year of undergraduate studies was evaluated, listing possible factors for persistence (risk) or improvement (protection) of allergic symptoms. A new skin prick test was performed, and questionnaires on asthma and rhinitis symptoms, quality of life, and risk factors for the development of respiratory allergies 13 were applied. Translational logistic regression models were applied to estimate the probability of changes in the state of sensitization over time. Sensitization tends to persist after being established, while spontaneous loss of sensitization is uncommon. It was observed that students with prolonged occupational exposure during veterinary medicine and animal science training do not necessarily present an increased risk of allergic sensitization, suggesting a possible role of immunological tolerance in this population. The findings highlight the importance of preventive strategies during academic training to reduce the future incidence of occupational allergic diseases.
Análise do nível de adequação das matrizes curriculares dos cursos de computação no Brasil ao modelo de competências
(Universidade Federal de Lavras, 2026-03-26) Nunes, Vítor Ferreira; Souza, Maurício Ronny de Almeida; Parreira Júnior, Paulo Afonso; Freire,André Pimenta; Ribeiro, Marcos Wagner de Souza
Computing is a dynamic field that demands constant adaptation to social and technological advancements. To align with labor market trends, the Brazilian Computer Society (SBC) published the Reference Curricula for undergraduate Computing courses in 2017, introducing a competency-based approach aimed at providing students with a more integrated, flexible, and relevant education. However, implementation within Higher Education Institutions (HEIs) is neither simple nor immediate, requiring a reconceptualization of teaching and learning, strategic planning, and collaborative management. Consequently, the core problem guiding this study addresses the challenges involved in implementing this approach within the curricula of Brazilian Computing courses. This study aims to analyze the adoption of CompetencyBased Education (CBE) in Brazilian Computing courses, following SBC guidelines. Methodologically, it is grounded in a bibliographic review of related works and discussions regarding competency-based teaching. Furthermore, documentary research was conducted on SBC reference documents and Pedagogical Course Projects (PPCs) from various universities to evaluate how competencies are defined and integrated. Complementarily, interviews with coordinators aimed to map their profiles, insights, challenges, and strategies regarding the implementation of this curriculum model. The results of the documentary analysis reveal that none of the examined PPCs fully meets the seven proposed evaluation criteria; the majority of courses satisfy only two items, with only five courses achieving five criteria. Interviews with coordinators corroborate this scenario, indicating, on one hand, clarity regarding the definition of graduate profiles and general competencies, and on the other, difficulties in articulating and institutionalizing teaching methodologies and assessment processes consistent with CBE, which often remain restricted to individual faculty initiatives. Based on these findings, a set of recommendations was developed to enhance the implementation of CBE-based curricula in Brazilian Computing courses, thereby contributing to the improvement of educational quality in the field.