https://repositorio.ufu.br/handle/123456789/5095 Mon, 01 Jun 2026 04:35:41 GMT 2026-06-01T04:35:41Z https://repositorio.ufu.br:443/retrieve/34196527-47f5-48f9-b9fb-a333cdc52783/iqufu.jpg https://repositorio.ufu.br/handle/123456789/5095 https://repositorio.ufu.br/handle/123456789/48718 Title: Influência da co-dopagem com íons La3+ em sistemas binários de óxidos de SiO2-TiO2:Eu3+ obtidos pelo método sol-gel Abstract: This study investigates the synthesis and characterization of photoluminescent materials based on SiO2-TiO2 matrices co-doped with Eu3+ and La3+. Prepared via the sol-gel method and calcined at 750 °C, the matrices were analyzed by X-ray Diffraction (XRD), Raman spectroscopy, Fourier-Transform Infrared spectroscopy (FTIR), Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM), and Photoluminescence (PL). Structural results confirmed the stabilization of the anatase phase, where the incorporation of La3+ acted as a crystal growth inhibitor, except at concentrations of 0.3 and 1.0 mol%, which exhibited a singular bulk-like behavior regime. Diffuse reflectance analysis (DRS) revealed an adjustable direct band gap between 2.75 and 3.02 eV, correlated with the structural disorder monitored by the Urbach energy. Thermal treatment proved crucial, promoting the removal of hydroxyl suppressors and resulting in an average 6.5-fold (547%) jump in luminescence lifetimes (τ), which reached values exceeding 1000 µs. Spectroscopic analysis indicated that La3+ co-doping induces a symmetry breaking at the Eu3+ local site (site symmetries Cs, Cn ou Cnv), evidenced by the splitting of the 5D0→7F1 transition into three singlets and a 120% increase in the emission intensity of the 5D0→7F2 hypersensitive band. In situ PL monitoring as a function of temperature confirmed the reversibility and thermal robustness of the system, mitigating quenching effects. These findings demonstrate the high potential of SiO2-TiO2:Eu3+,La3+ composites for the development of advanced photonic devices, such as WLEDs and high-sensitivity sensors for optical thermometry. Wed, 17 Dec 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48718 2025-12-17T00:00:00Z https://repositorio.ufu.br/handle/123456789/48691 Title: Development of conductive and printable filaments for electrochemical sensors applied to environmental, pharmaceutical, food and biological analyses Abstract: Chemical sensors have been widely developed in response to the growing demand for the monitoring of analytes in environmental, biological, forensic and food samples. Among them, electrochemical sensors stand out for translating chemical information into measurable electrical signals and for offering advantages such as good selectivity, sensitivity, low limit of detection, ease of miniaturisation and versatility for both materials and designs. In this context, these devices have grown together with advances in new manufacturing technologies, especially additive manufacturing, which has emerged as a promising approach for the production of electrochemical sensors. In parallel, new conductive filaments have been developed to improve electrochemical responses, expand possibilities for new applications and incorporate sustainability perspective. However, as this is still a relatively recent field, challenges remain in regard to the achievement of improved electrochemical responses, better printability and the use of new polymers to broaden applications. Thus, this Thesis aimed to explore the fabrication and application of new alternative filaments produced in the laboratory for the monitoring of paracetamol, ascorbic acid, dopamine, uric acid, nitrite and carbendazim, demonstrating the versatility of these devices in environmental, biological and food samples. Divided into six chapters, the work presents: general introduction, filaments modified with carbon nanodiamonds and functionalised nanodiamonds, demonstrating the possibility of modifying and improving electrochemical responses; filaments with the addition of edible oils as plasticisers, with a focus on sustainability and demonstrating, for the first time, the influence of specific plasticisers on sensor responses; alternative thermoplastic polyurethane (TPU)-based filaments, used both as sensors obtained from the direct use of the filament itself and as printed electrodes which, compared with polylactic acid (PLA), show greater flexibility without loss of analytical performance, in addition to biocompatibility, thereby expanding the potential for application in wearable sensors; and, finally, more sustainable filaments produced from high-density polyethylene recycled (rHDPE) from cleaning-product packaging, with emphasis on greater chemical resistance and durability when compared with other polymers. All materials were extensively characterised, and the electroanalytical devices were evaluated against the proposed applications. The results expand the possibilities for the development and optimisation of electrochemical sensors, highlighting efficient, versatile, low-cost materials with low waste generation. Fri, 08 May 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48691 2026-05-08T00:00:00Z https://repositorio.ufu.br/handle/123456789/48628 Title: Memorial descritivo da trajetória acadêmica e profissional Abstract: I am Fábio Augusto do Amaral and I present this descriptive memorial as a reflective requirement of my journey, necessary for the promotion to the rank of Full Professor at the Institute of Chemistry of the Federal University of Uberlândia. My trajectory is the result of quality public education, from my early literacy in Várzea Paulista, technical school at SENAI and at the Antenor Soares Gandra school, both in Jundiaí, to my academic consolidation at UFSCar, where I completed all of my higher education, with a Bachelor's and Licentiate degree in Chemistry, culminating in a PhD in Sciences, emphasis in Electrochemistry, finalized in 2005. After a period of pedagogical maturation at the University of São Francisco, I joined UFU as a faculty member in 2010, committed to the inseparability between the various university spheres, such as my work in teaching, research, extension, and management. In Teaching, I have always taken on various disciplines of different natures and workloads, providing a solid and necessary education for undergraduate and/or graduate students. In the scope of Research, my work, since the establishment of the Laboratory of Analytical, Electrochemistry, and Wastewater Treatment (LAETE), has been one of partnership, initially with Sheila Cristina Canobre, my partner in this journey, until the present moment, with the incorporation of Ricardo Brocenschi (a former advisee) and Rodrigo Amorim (son of a friend from UFU). There, I develop research focused on the extraction/separation of polymeric fractions from biomass, originating from agro-industrial waste for various applications and, in the area of Electrochemistry, both in energy storage (solid polymer electrolytes) and in the detection/degradation of emerging contaminants. The collaboration at LAETE has allowed the publication of dozens of scientific articles in medium/high-impact journals, in addition to the supervision of numerous undergraduate research and graduate students, strengthening national science. In University Extension, my dedication reflects the belief that knowledge must overflow the walls of academia. I highlight the creation of the IQUFU Umbrella Extension Program, the Café na Química (focused on the dissemination of Science), and the coordination of the Leveling Courses in Mathematics and Chemistry, a project that has already reached its tenth edition (reaching more than two thousand students), both fulfilling, respectively, a vital social role of disseminating IQUFU's actions to the community and welcoming incoming students to the University, preparing them for the challenges of higher education. I would also highlight my effective participation in the Chemistry of Things Exhibition (now in its third edition), which takes Science beyond the University walls. But it was in Management that I had the greatest prominence, both in the coordination of two undergraduate courses (Bachelor's in Industrial Chemistry and Licentiate), leading strategic curricular reforms, and as Director of the Institute of Chemistry, where I sought to modernize curricula, update regulatory documentation, and optimize administrative processes. The management model adopted by my administration is innovative, as it strictly follows the principle of equity between technical staff and faculty, distributed into five advisory chambers (Budget, Planning and Infrastructure, Teaching, Extension, and Research and Graduate Studies), which are consultative and guide the Institute of Chemistry Council (CONIQ) in decision-making. Incidentally, I have been presiding over CONIQ for two terms, being the first director of IQUFU to serve two consecutive mandates. All of this trajectory, marked by a consistent score in every year, demonstrates a balance between scientific rigor and administrative commitment. I view this new stage that is to come not as a final point in my career, but as the maturation of a career dedicated to human formation and scientific/technological progress. I remain motivated to contribute so that the public university continues to be an agent of social transformation and academic excellence. I remain committed to honoring those who taught me, maintaining an active role in the human and academic construction of my students, the greatest reason for my efforts and struggles. In the end, this memorial is also about the people who build me daily, in my successes and mistakes, but always in the certainty of being a good public servant. Fri, 20 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48628 2026-03-20T00:00:00Z https://repositorio.ufu.br/handle/123456789/48601 Title: Memorial Descritivo da Trajetória Acadêmica e Profissional Thu, 26 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48601 2026-03-26T00:00:00Z