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dissertação
Controle magnetoelástico das correlações quânticas e sensibilidade ao campo magnético em um dímero de Heisenberg de spin 1/2
(Universidade Federal de Lavras, 2026-08-17) Souza, Eduardo Wallace Braga de; Santos, Onofre Rojas; Leyva, Moises Porfirio Rojas; Oliveira, Igor Saulo Santos de; Pereira, Maria Socorro Seixas
This work investigates magnetoelastic effects in a spin-1/2 Heisenberg dimer by explicitly considering the influence of internal vibrational modes on its thermal, magnetic, and quantum properties. Unlike the usual linear approach, the developed model incorporates second-order magnetoelastic corrections in the relative displacement between spins, providing a more realistic description of the coupling between magnetic and vibrational degrees of freedom. Through the diagonalization of the magnetoelastic Hamiltonian and the construction of the partition function, renormalized energies, effective vibrational frequencies, and thermal populations associated with different spin sectors are obtained. Based on these quantities, the mean magnetoelastic displacement, vibrational fluctuations, magnetization, magnetic susceptibility, and ground-state phase boundaries are analyzed. In addition, the work investigates thermal quantum correlations through concurrence, local quantum uncertainty, and quantum Fisher information, emphasizing the effects produced by thermal population redistribution and vibrational renormalization of the energy spectrum. The results show that second-order corrections significantly modify the stability of magnetic phases, the energy gaps between eigenstates, and the robustness of quantum correlations, highlighting the relevance of magnetoelastic effects in low-dimensional quantum systems.
dissertação
Leitura literária e produção escrita no ensino fundamental: um estudo a partir da proposta de sequência básica de Rildo Cosson
(Universidade Federal de Lavras, 2026-04-22) Costa, Maísa Maria; Goulart, Ilsa do Carmo Vieira; Ferreira, Helena Maria; Montuani, Daniela Freitas Brito
This study discusses literary literacy as a process of inserting the reader into the social practices of literary reading, promoting the construction of meaning, aesthetic appreciation, and the development of critical thinking. In this sense, it is understood that pedagogical strategies can foster the comprehension of written language and integrate it into reading and text production practices, as a fundamental element for the effective development of students’ linguistic skills. Therefore, the following question is raised: How do literary reading practices support text production activities in a way that enhances reading comprehension? In light of this, the present study aims to investigate how literary reading practices can contribute to retextualization processes from oral to written language, based on the basic sequence proposed by Rildo Cosson (2006), with a 3rd-grade elementary school class. The specific objectives are: (1) to develop literary reading activities focused on narrative genres, with an emphasis on retextualization practices from oral reading to writing; (2) to verify the children's reading comprehension process through guiding questions about the texts studied; and (3) to monitor the development of students’ literary reading and retextualization practices throughout the 2025 school year. This is a participatory study with a mixed qualitative and quantitative approach, employing reflective analysis and using strategies such as observation of field records, planning, and materials used in literary reading and text production activities. The activities were based on children's literature books written by Regina Rennó and Ruth Rocha. The study is grounded in Soares (2004) on literacy, Cosson (2006) on literary literacy, Marcuschi (2010) on orality and writing, Goulart (2016) and Cardoso (2002) on written production, among other theorists who support this research. Based on this theoretical framework, issues related to writing, written production, and literary literacy are discussed. The activities carried out and the texts produced by the participants constituted the corpus of analysis for validating the proposed hypotheses. As an educational product, a basic sequence based on Cosson’s proposal was developed to document the stages of the research, the activities carried out, and a small sample of texts produced by the students, aiming to disseminate the results.
dissertação
Residualidade do calcário e seus efeitos na produtividade de grãos em áreas sob sistema de plantio direto
(Universidade Federal de Lavras, 2025-11-26) Moraes, Vítor Soares Olivério de; Moreira, Silvino Guimarães; Lopes, Guilherme; Silva, Thais Palumbo
Surface liming in no-tillage systems (NTS), without mechanical incorporation, can effectively ameliorate soil acidity and increase the availability of exchangeable calcium (Ca²⁺) and magnesium (Mg²⁺). However, lime reaction and the downward movement of its reaction products are generally slower under surface application than under incorporation, particularly in soils with high buffering capacity. Uncertainty regarding appropriate lime rates and the frequency of reapplication may limit crop productivity. In addition, the need to reincorporate lime in soils managed under NTS remains uncertain, particularly in areas where soil fertility was not adequately built before the adoption of the system. Therefore, this study aimed to evaluate the effects of surface-applied lime rates, compared with an incorporated rate to a depth of 0.25 m, on soil chemical attributes and annual crop productivity under NTS, as well as to assess the efficiency and persistence of the residual effects of lime four years after application. The experiments were conducted independently from 2019 to 2024 in a randomized complete block design, with four replications, at four sites located in the municipalities of Carrancas (Site I), São João del-Rei (Site II), Ingaí (Site III), and Uberlândia (Site IV), representing soils with contrasting textures. The treatments consisted of five lime rates (0, 2, 4, 6, and 8 Mg ha⁻¹) applied to the soil surface, plus an additional treatment consisting of 8 Mg ha⁻¹ incorporated into the soil, resulting in a total of 24 plots of 200 m². Surface liming increased exchangeable and residual Ca²⁺ and Mg²⁺ contents, soil pH, and base saturation (V%), while decreasing H+Al contents. Four years after lime application, the residual effect of the amendment remained evident. Increases in soil pH and reductions in potential acidity in the 0.10–0.20 and 0.20–0.40 m layers indicated the downward movement of lime reaction products into the subsurface layers, accompanied by increases in exchangeable and residual Ca²⁺ and Mg²⁺ contents. The highest surface-applied lime rates produced greater corrective effects across the three evaluated soil depths, except at Site IV, which had the lowest clay content, highlighting the role of soil buffering capacity in determining liming efficiency. The incorporated rate was more effective than the lower surface-applied rates, particularly at Site IV, where incorporation resulted in marked increases in all evaluated soil chemical attributes. These results demonstrate that liming efficiency is strongly influenced by soil texture and buffering capacity and that the effects of liming can persist for several years, with residual lime remaining in the soil. Although incorporation promotes faster and more uniform amelioration throughout the soil profile, surface application can also provide substantial improvements when an adequate lime rate is applied. During the final two years of cultivation, beginning three years after lime application, increases in crop productivity in response to surface-applied lime rates were observed at Sites II and IV, particularly during the 2024/24 growing season, which was characterized by lower water availability. Except at Site I, cumulative productivity over the final two growing seasons increased with increasing surface-applied lime rates, whereas lime incorporation did not result in significant increases in crop productivity.
tese
Spray-dried porcine blood as nutritional and functional ingredient: stabilization strategies, characterization and application in bologna-type sausages
(Universidade Federal de Lavras, 2026-08-21) Carmo, Lorrany Ramos do; Ramos, Eduardo Mendes; Ramos, Alcineia de Lemos Souza; Paula, Marielle Maria de Oliveira; Fontes, Paulo Rogério; Cunha, Aureliano Claret da
Porcine blood is a by-product with high nutritional and technological potential, but its use as a food ingredient is limited by the susceptibility of heme proteins to oxidation and color changes during processing and storage. This study aimed to evaluate the effects of pretreatment of porcine blood with sodium nitrite and S-nitroso-N-acetylcysteine (NAC-SNO), prior to spray drying, on the characteristics and stability of the resulting blood powder and its application as an ingredient in a meat product. Initially, different pretreatment conditions were evaluated, and those resulting in greater nitrosyl pigment formation were selected. Untreated blood and blood pretreated with sodium nitrite or NAC-SNO were spray-dried and characterized regarding their physicochemical, nutritional, and technological properties, pigment formation, and oxidative and color stability during storage. Subsequently, the resulting powders were incorporated into bologna-type sausages as partial or total replacements for soy protein isolate, and their technological, nutritional, and physicochemical properties, as well as their stability during refrigerated storage, were evaluated. The blood powders had a protein content above 85%, and the pretreatments increased nitrosyl pigment formation (P < 0.05), increasing its conversion from 0.29% in the control to 39.50% and 46.93% in the sodium nitrite and NAC-SNO treatments, respectively. NAC-SNO showed greater preservation of sulfhydryl groups, Snitrosothiols, and nitrosyl pigments during storage, particularly in the absence of light (P < 0.05). In the application in bologna-type sausages, replacement of soy protein isolate with blood powder did not compromise emulsion stability or texture properties and increased the iron content of the products (P < 0.05). Pretreatment with sodium nitrite and NAC-SNO reduced lipid oxidation compared with untreated blood (P < 0.05), without affecting residual nitrite content or microbiological stability. Thus, pretreatment of porcine blood prior to spray drying altered the properties of the ingredient and enabled its application as a source of protein and iron in bologna-type sausages, contributing to the utilization of porcine blood as a by-product of the meat industry.
tese
Valorização dos taninos da casca e dos frutos de Anadenanthera colubrina var. Cebil como revestimentos sustentáveis para papel de embalagem de alto desempenho
(Universidade Federal de Lavras, 2026-06-25) Lourenço, Yanka Beatriz Costa; Guimarães Júnior, José Benedito; Protásio, Thiago de Paula; Mori, Fábio Akira; Mendes, Lourival Marin; Arantes, Lorran de Sousa; Guimarães Neto, Rosalvo Maciel; Sousa, Thais Brito
The increase in plastic waste generation and the need to reduce dependence on nonrenewable resources have spurred the development of biodegradable materials derived from renewable sources that can meet market demands without compromising environmental sustainability. In this context, the use of condensed tannins as a coating for packaging paper has attracted the interest of researchers due to their antioxidant properties, UV radiation absorption, and ability to form interactions that can improve the barrier properties, mechanical strength, and stability of materials. Among the species with potential for obtaining these compounds, Anadenanthera colubrina var. cebil stands out, widely known for its pharmacological use and the high tannin content present in its bark. However, other parts of the plant, such as the fruits, remain largely unexplored. Given this, the objective of this study was to evaluate the potential of tannins extracted from the bark and fruits of A. colubrina var. cebil for application as a coating on kraft sack paper. The results demonstrated that both bark and fruit tannins can be used as coatings for packaging paper. In general, bark tannins exhibited better adhesion to the substrate and greater potential for applications aimed at improving barrier properties. In contrast, fruit tannins exhibited distinct behavior, associated with their chemical composition, indicating potential for specific applications that require greater interaction with adhesives or other polymeric matrices. The results obtained expand the possibilities for utilizing this species and reinforce the potential for using its tannins in the development of sustainable coatings for packaging papers.