DSpace Collection:https://repositorio.ufu.br/handle/123456789/217722026-04-23T15:11:15Z2026-04-23T15:11:15ZNanopartículas semicondutoras: síntese e caracterizaçãohttps://repositorio.ufu.br/handle/123456789/484632026-03-04T06:26:25Z2025-05-20T00:00:00ZTitle: Nanopartículas semicondutoras: síntese e caracterização
Abstract: Semiconductor nanomaterials play a fundamental role in the manufacturing of modern electronic devices, including LEDs, displays, fiber-optic communication systems, and lasers. Technological development requires a constant search for new materials and synthesis methods. In this Undergraduate Thesis (TCC), nanoparticles based on Carbon Dots (CDs) and group II-VI semiconductors we synthesized and characterized, aiming to explore their optical and electronic properties. Optical characterization was performed using techniques such as photoluminescence (PL), photoluminescence excitation spectroscopy (PLE), and absorbance measurements, enabling a detailed investigation of light absorption and emission mechanisms, as well as the coupling between electronic states. The PL spectra were analyzed through deconvolution into Gaussian curves, which allowed the identification and separation of contributions from different emissive centers present in the Carbon Dots. To evaluate the stability of the samples' optical properties, we studied the fitting parameters of the luminescence spectrum immediately after synthesis and then six months later. We observed that some of these fitting parameters vary over time, while others tend to remain constant, which is of crucial importance for applications of these structures in optoelectronic devices. Finally, the dependence of PL spectra on the excitation wavelength was investigated, providing relevant conclusions about the nature of the emissive sites and their characteristic energies. This approach allowed us to distinguish between emissions related to surface states and transitions involving the core of the nanoparticles. We believe this work was beneficial for our academic development, providing practical and theoretical knowledge in the synthesis and characterization of new semiconductor materials, a field of critical importance for the advancement of nanotechnology.2025-05-20T00:00:00ZSíntese e caracterização de pontos quânticos de carbono a partir da pirólise da palha de milho e oxidação dos produtoshttps://repositorio.ufu.br/handle/123456789/477472025-11-26T06:19:11Z2025-05-07T00:00:00ZTitle: Síntese e caracterização de pontos quânticos de carbono a partir da pirólise da palha de milho e oxidação dos produtos
Abstract: This study aims to produce carbon dots (CDs) from corn husks using pyrolysis as the synthesis method. The corn husks were subjected to a temperature of 300 °C in a muffle furnace, with 3 mL of nitric acid (HNO₃) used as the oxidizing agent. Temperature and exposure time were key variables in the formation of CDs. Six samples were prepared with treatment durations of 1, 2, and 3 hours to analyze structural and optical changes. Characterization by Fourier-transform infrared spectroscopy (FTIR) indicated the presence of nitrogen-containing functional groups, confirming the carbonization of the material. Ultraviolet-visible (UV-Vis) absorption spectra showed bands between 270 and 340 nm related to π-π* transitions of C=C bonds in the graphitic structure, and a band around 350 nm associated with n-π* transitions of carbonyl (C=O) groups. Additionally, luminescence emission was observed when the samples were excited at specific wavelengths, with varying emission intensities—ranging from low 69 (u.a) to high 318 (u.a) depending on particle size and quantum confinement effects, which influence the optical behavior of the CDs.2025-05-07T00:00:00ZA presença do cinema no livro didático e suas contribuições ao processo de ensino-aprendizagem de físicahttps://repositorio.ufu.br/handle/123456789/477332025-11-25T06:20:07Z2025-09-12T00:00:00ZTitle: A presença do cinema no livro didático e suas contribuições ao processo de ensino-aprendizagem de física
Abstract: This study aimed to analyze how cinema is addressed in a collection of Natural Sciences
textbooks, investigating its potential as a didactic resource within the physics teaching-learning
process and students’ scientific education. The documentary research, of a qualitative nature,
revealed that references to films are occasional and mostly suggested superficially, with limited
pedagogical depth. Based on the premise that it is essential to adopt methodologies that resonate
with students’ interests and contemporary cultural dynamics, the results suggest possibilities
for a more meaningful integration of cinema into scientific content. It was noted that one of the
referenced films belongs to the biographical drama genre, typically associated with narratives
of creativity, overcoming challenges, and social transformation — aspects which, even when
briefly explored, indicate potential for articulating science, historical context, and critical
education. Therefore, the study proposes expanding the presence of cinema in textbooks, as
well as adopting a more contextualized approach aligned with students lived realities.2025-09-12T00:00:00ZAtividades didáticas de resolução de problemas e aprendizagem pela pesquisa: possíveis articulações no livro didático de físicahttps://repositorio.ufu.br/handle/123456789/461102025-06-12T06:18:30Z2025-05-09T00:00:00ZTitle: Atividades didáticas de resolução de problemas e aprendizagem pela pesquisa: possíveis articulações no livro didático de física
Abstract: This study examines potential connections between problem-solving instructional activities and inquiry-based learning in physics textbooks used in Brazilian high schools (Ensino Médio) within the Triângulo Mineiro region. Acknowledging textbooks' role as key pedagogical resources, we analyze how problem-solving activities incorporate guidelines for developing research-oriented tasks, particularly those extending beyond classroom settings. Our specific objectives include evaluating how these problem-solving activities contribute to student-centered research strategies. Employing qualitative document analysis with Content Analysis methodology, we examined the two most widely-used textbook collections in public schools across the region, assessing their pedagogical approaches and provisions for student research. Findings reveal that while some activities suggest investigative practices, most emphasize superficial information gathering and mechanical problem-solving rather than active knowledge construction. Certain activities demonstrated stronger potential for inquiry-based learning, though their effectiveness depends on teachers' critical implementation. We conclude that while the analyzed textbooks offer opportunities for research-based learning, their efficacy requires reflective and creative teacher mediation. The study underscores the need for ongoing teacher professional development and pedagogical practices that bridge scientific knowledge with societal needs, fostering critical, meaningful, and transformative education.2025-05-09T00:00:00Z