https://repositorio.unifei.edu.br/jspui/handle/123456789/56 2026-04-07T13:31:10Z 2026-04-07T13:31:10Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4337 2026-02-06T13:28:53Z 2025-12-09T00:00:00Z

Nanopartículas híbridas termossensíveis baseadas em proteína-polímero como um potencial sistema carreador de agentes terapêuticos contra o câncer In recent years, hybrid materials combining proteins and polymers have attracted significant interest in the biomedical field, particularly in the development of controlled drug delivery systems. The conjugation of these two classes of materials enables the integration of biocompatibility, stability, and functionality into a single system. Among natural proteins, silk fibroin (SF) stands out as a promising biocompatible material, while poly(N-vinylcaprolactam) (PNVCL) offers a thermoresponsive behavior suitable for therapeutic applications. In this context, the SF–PNVCL hybrid system emerges as an innovative strategy for the development of nanocarriers capable of responding to specific stimuli, such as temperature increases, thereby optimizing the release of therapeutic agents. In this work, novel thermoresponsive hybrid systems based on silk fibroin (SF) and PNVCL were developed, aiming to produce nanoparticles capable of promoting controlled release of therapeutic agents, using curcumin as a model drug. The hybrid systems were synthesized using a grafting-from strategy via reversible addition-fragmentation chain-transfer (RAFT) polymerization, through the functionalization of fibroin with chain transfer agents (CTA1 and CTA2). A second synthetic route was established by activating CTA2 with pentafluorophenol (PFP). The systems were characterized by Fouriertransform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). The nanoparticles were further evaluated by dynamic light scattering (DLS), zeta potential measurements, and transmission electron microscopy (TEM). The results revealed that the hybrid systems exhibited nanoparticulate morphology (~200 nm), good colloidal stability, and a thermoresponsive phase transition near 40 °C. Additionally, the nanoparticles demonstrated curcumin encapsulation efficiency of approximately 40%, with enhanced release at elevated temperatures. The release kinetics showed a better fit to the Weibull and Gompertz models (R² > 0.99), indicating a controlled and thermoresponsive release process. In vitro cytotoxicity assays, evaluated by flow cytometry, revealed low toxicity in normal cells (MRC-5) and high selectivity toward the 4T1 cancer cell line, with up to 49.5% cell inhibition. Based on these findings, SF– PNVCL hybrid systems represent a promising platform for the development of smart carriers for targeted therapeutic applications. Tese

2025-12-09T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4323 2025-12-03T11:28:42Z 2025-07-02T00:00:00Z

Análise e implementação de um algoritmo de sensação de movimento em uma plataforma de 2 graus de liberdade para treinamento de operadores de caminhões fora de estrada Vehicle simulators in mining environments play an increasingly vital role in the development and training of operators, offering high safety, reliability, low cost, and the ability to create scenarios that would be difficult to reproduce under real conditions. However, due to spatial constraints, simulators cannot fully replicate the movements of real vehicles, especially off-highway trucks like the CAT793F, which exhibit distinct behaviors in acceleration, braking, turning, and other maneuvers. This work presents a methodology for implementing a washout-type Motion Cueing Algorithm (MCA) on a motion platform with two degrees of freedom (DoF), designed to simulate pitch and roll movements consistent with the operating conditions of mining trucks. The proposed algorithm was compared with an alternative approach and showed promising results, with better motion representation, lower response delay, and reduced system-induced noise. The evaluation of the results was conducted in three main stages: initially through an objective analysis using the OMCT (Objective Motion Cueing Test), followed by a comparison with the expected response of the human vestibular system, highlighting a good similarity, especially in the semicircular canals. Finally, the influences of noise and disturbances observed in the platform’s response were considered, with these deviations being strongly associated with dynamic effects resulting from the lack of anchoring of the base to the ground. This condition favors undesired displacements and imbalances during motion, directly affecting the accuracy of the simulation and the stability of the system. Dissertação

2025-07-02T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4319 2025-11-10T13:00:19Z 2025-02-20T00:00:00Z

Análise das fases cristalinas na soldagem GTAW de aço inoxidável AISI 316L revestido por Níquel-Watts utilizando Thermo-Calc This study investigates the microstructure and mechanical properties of the austenitic stainless steel AISI 316L after performing GTAW (TIG) welding using commercially pure argon gas (with 2% oxygen) at the ends of sheets that were previously subjected to nickel electrodeposition, containing a nickel-Watts solution enriched with niobium particulate (with a particle size of less than 150 µm) at room temperature. To evaluate the mechanical properties and microstructural changes, tensile tests, potentiodynamic polarization, Vickers microhardness, ferritoscopy, and microstructural analyses were conducted. The welding resulted in the formation of austenitic and delta ferrite (δ) phases, with a pronounced concentration in the molten zone (MZ), attributed to the rapid cooling characteristic of the welding process. Additionally, the emergence of metallic carbides and sigma (σ) phase was observed at grain boundaries, particularly in the heat-affected zone (HAZ). Ferritoscopy revealed a significant increase in the volumetric fraction of ferromagnetic phases in the welded regions, reaching 6.7% Fe in the MZ, 3.3% Fe in the HAZ, and 0.5% Fe in the base metal (BM). The microhardness results demonstrated differences among the analyzed regions, with the ZF exhibiting the highest microhardness value (231 HV ± 7 HV), followed by the ZTA with an intermediate value (188 HV ± 6 HV), and the base metal (BM) showing the lowest value (174 HV ± 1 HV). In the potentiodynamic polarization tests, the results indicated minimal variations in corrosion and pitting potentials between the base metal and the welded samples. For the welded sample, the average corrosion potential was measured at 0.02 V ± 0.01 V, with an average pitting potential of 0.24 V ± 0.01 V. Conversely, the base metal exhibited an average corrosion potential of 0.05 V ± 0.01 V and an average pitting potential of 0.29 V ± 0.01 V. Microfractographic analyses characterized the fracture of the welded samples as ductile, with the presence of dimples indicating a good capacity for deformation prior to rupture. Despite the addition of niobium to the nickel-Watts solution, the formation of niobium precipitates in the material was not identified, which may be attributed to the low thickness of the coating compared to the thickness of the weld bead, resulting in insignificant improvements in mechanical properties and corrosion resistance. Dissertação

2025-02-20T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4229 2025-05-06T14:11:14Z 2024-11-23T00:00:00Z

Evolução dos instrumentos de gestão dos recursos hídricos em Minas Gerais: estudo de caso das bacias hidrográficas dos Rios Paracatu e Piracicaba In Brazil, concern about water management is clearly seen in the state of Minas Gerais, with strong action by the water resources management body, the Minas Gerais Institute for Water Management (IGAM), together with the National Water and Basic Sanitation Agency (ANA), the River Basin Committees (CBHs) and other local authorities. Water management in the state relies on the use of the five management instruments set out in the so-called Water Law: water resources plans; classification of water bodies into classes; granting of rights of use; charging for the use of water resources; and an information system. In this context, this work assesses the implementation and evolution of these instruments in Minas Gerais, with an emphasis on the Paracatu (a tributary of the São Francisco River) and Piracicaba (a tributary of the Doce River) river basins, which play an important role in the state's economy, with agricultural and mining activities predominating, respectively. The work methodology included consultations to understand not only the process of implementation and evolution of the management instruments, but also the characterisation of the study areas in terms of physiographic, economic and other aspects, in order to find out how these factors can influence the water availability of the basins. Thus, the results obtained show the history of the implementation of the instruments in the basins studied and allow us to identify the main challenges already faced, among them the lack of updating and monitoring of the fulfilment of the targets set in the water resources plans and the difficulty in managing grants, which has led to water shortages in some regions. The results make it possible to identify the gains from implementing the charging instrument, so that the amounts collected help to protect the river basin, preserve springs and watercourses, as well as enabling the financial execution of various projects. Thus, the results obtained in this study allow us to conclude that the mere implementation of these instruments is insufficient, and that assertive management is needed that takes into account the specificities of each river basin. Dissertação

2024-11-23T00:00:00Z