Navegando por Assunto "Micro"

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Acesso aberto (Open Access)
Formação de heteroestruturas compostas por microtubos de Cu/Cu2O/CuO decorados com nanocristais de CoO
(Universidade Federal do Pará, 2024-08-21) SANTOS, Suzilene Vasconcelos dos; PASCA, Gabriel Adolfo Cabrera; http://lattes.cnpq.br/5642784995274060; https://orcid.org/0000-0002-9411-0889
A particularly important class of micro/nanostructured materials is that of transition metal oxides. In this work, copper and cobalt oxides are used to obtain micro/nanostructures. Copper (II) oxide (CuO) and copper (I) oxide (Cu2O) are p-type semiconductors, widely studied due to their peculiar characteristics and potential technological applications. Specifically, copper (Cu) microwires with approximately 50 μm in diameter and 4 cm in length, extracted from discarded cellphone earphones, were subjected to thermal treatments at 600°C with different synthesis parameters to obtain CuO microtubes. On the other hand, cobalt acetate was used in the synthesis of nanoparticles through the chemical method called thermal decomposition, which uses organometallic salts in organic solvents, being a suitable method for the synthesis of CoO nanostructures. Metallic cobalt and its oxides have been intensively studied due to numerous applications enhanced by their properties. CoO nanoparticles exhibit instability in the hexagonal close-packed Wurtzite structure (hcp - space group P63mc). This implies that, depending on the synthesis parameters, phase transition can occur, that is, from CoO-hcp to CoO-fcc (face-centered cubic phase - space group Fm3m), which is considered the most stable phase for CoO. However, in order to obtain a hierarchical structure of CuO microtubes decorated with CoO nanoparticles, this work uses different synthesis methodologies to produce a micro-nano-hierarchical structure. In this study, X-ray diffraction was used to identify the crystalline structures present in the microwires and nanoparticles, highlighting the influence of the time parameter on the phase transition of both structures. The morphological characterization of the samples was performed using scanning electron microscopy (for the microwires) and transmission electron microscopy (for the nanoparticles). Raman spectroscopy was also employed to obtain information about the sample surfaces. With these characterization techniques, it was possible to determine the elemental and structural composition of the microtubes and nanoparticles composed of copper and cobalt oxides, as well as to evaluate the influence of the laser on the nanoparticle samples. Thus, a Cu/Cu2O/CuO heterostructure with CoO monocrystals on the surface was developed, presenting potential sensory properties.
Acesso aberto (Open Access)
O uso do micro: bit como ferramenta educacional para promoção do pensamento e do letramento computacional a partir da PBL
(Universidade Federal do Pará, 2021-11-12) ALBUQUERQUE, Márcia Cristina Palheta; FONSECA, Wellington da Silva; http://lattes.cnpq.br/5066230825214516; https://orcid.org/0000-0002-2602-1964
The changing scenario in education has materialized with the accelerated advance in the use of technological resources in schools. Several methodologies with different approaches that help teaching and learning in the classroom have been increasingly studied, such as the use of Educational Robotics (ER) and the use of microcontrollers. Given the scenario described, the guiding question of this research is based on: How ER can generate improvements in the teaching-learning of students through PBL and the STEAM methodology? Therefore, this work presents results from the use of an educational technological tool through the BBC Micro: bit platform, aiming to provide students with a way to engage, motivate and promote thinking and computer literacy. Project-Based Learning (PBL) and the STEAM methodology (Science, Technology, Engineering, Arts, Mathematics) were used in this research. Based on the projects developed using Micro: bit, a short course was applied to students in the first year of the Technician course in Informatics – high school – at the School of Technical Education of the State of Pará “Dr. Celso Malcher”. During the short course, the preliminary version of the educational product resulting from this research was used, which consists of a book in digital format based on the foundations of the Brazilian Educational Curriculum, and containing the proposed activities and directing links (websites, QR code) to the complementary videos referring to each activity. This research is of a qualitative case study type. Data were obtained through the students' answers collected in questionnaires before and after the application of the short course, in addition to the records in the researcher teacher's logbook. The results obtained were analyzed descriptively in the light of the theoretical framework relevant to the topic. With that, from the analyzed results, it was observed that the Micro: bit can be used as an educational tool to teach the contents seen in the classroom, mainly when using the PBL and the STEAM methodology in an integrated way. Students were able to develop projects with the platform, constituting an educational tool that stimulates and motivates creativity, which can contribute to the insertion of thinking and computer literacy, as well as to streamline learning. Therefore, it is observed that research in ER, through the use of BBC Micro: bit, presents an important contribution to studies on digital educational tools aimed at teaching and learning students.