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Nanoestructured catalysts for organic reactions: design, synthesis and applications
(Universidade Federal de São Carlos, 2016-07-29) Lima, Carolina Guimarães de Souza; Paixão, Márcio Weber; https://lattes.cnpq.br/3773908504964104; https://lattes.cnpq.br/8050810029110335
The development of more efficient and selective catalysts actively contributes for the design of safer, cleaner and less energy-demanding processes, and, therefore, catalysis is one of the cornerstones of green chemistry. In this sense, supported-heterogeneous catalysts represent a great advance in this field, especially because they overcome the difficulty in catalyst separation associated to homogeneous catalysts. In this context, this thesis is focused on the development of nanostructured materials for application in Organic Synthesis. In Chapter 1, a brief introduction regarding fundamental concepts in catalysis is presented, focusing on the synthesis and application of magnetically recoverable catalysts. Chapter 2 described the design, preparation and characterization of a new magnetically recoverable niobium nanocatalyst for application in the synthesis of 3,4-dihydropyrimidinones via Biginelli reaction. The catalyst (Fe3O4@Nb2O5) was prepared by coating magnetite nanoparticles with niobium oxide by using a simple wet impregnation method. The developed protocol was applicable to a wide range of aliphatic and aromatic substrates, and structurally diverse products were obtained in excellent yields. Additionally, the nanocatalyst could be easily separated from the reaction mixture with the aid of a magnetic field and reused several times without any losses in its catalytic activity. Moreover, experimental observations provided an insight into the reaction pathway. Chapter 3 describes the synthesis and characterization of a magnetic ZSM-5 zeolite with core-shell type structure for application on the valorization of bio-derived furfuryl alcohol. The magnetic HZSM-5 zeolite catalyst was prepared by the encapsulation of magnetite particles in the zeolite grains using a cationic polymer followed by calcination and next, an ion exchange to obtain the zeolite in its acid form. Remarkably, the catalytic system displayed a tunable selectivity to γ- valerolactone, alkyl levulinates and even levulinic acid by simply changing the reaction conditions. Furthermore, the catalyst could be easily recovered and reused for several reaction cycles without significant losses in its catalytic activity.
Junho, 2013 : o acontecimento discursivo transmídia
(Universidade Federal de São Carlos, 2016-07-29) Padovani, Gustavo; Massarolo, João Carlos; https://lattes.cnpq.br/3308336910966465; https://lattes.cnpq.br/2674652563269825
The manifestations occured in June 2013 in Brazil were marked by a large content production by a great diversity of users, indie medias and the traditional media. Whitin this premise, this research uses discourse analysis as a methodology to observe how interactions between contents produced by users in platforms as Facebook, YouTube, and the Twitcasting and media portals promote a discursive transmedia happening. As a study case, the research also analyses the alternative media collective Mídia Ninja, analyzing its production structure and how it´s contents promoted interactions with the traditional media, promoting discutions on the new relationship between activism and media.
Estudo e caracterização de acabamentos acrílicos para pisos
(Universidade Federal de São Carlos, 2016-07-29) Caressato Junior, Carlos Alberto; Silva, Caio Marcio Paranhos da; https://lattes.cnpq.br/7793686262868668; https://lattes.cnpq.br/8987383853019778
Through this work, it was possible to develop comparative analysis for acrylic floor coatings mainly used for resilient floors. The objective here was to make the performance evaluations less subjective and also create scientific arguments to compare the three commercially available products evaluated in this study. Some analytical methods, such as mechanic wear, infrared (ATR), thermal analysis like DSC and TGA, water vapor permeation and sortion in water, made it possible to understand better the behaviors like cure and physical-chemical resistance of these floor coatings, as well as it will be useful for future new product developments.
A geometria no ciclo de alfabetização : outros olhares a partir do PNAIC 2014
(Universidade Federal de São Carlos, 2016-07-29) Francischetti, Elisângela Aparecida; Passos, Cármen Lúcia Brancaglion; https://lattes.cnpq.br/2297203444364327; https://lattes.cnpq.br/3590894642507602
The present research aims to identify the perceptions of four literacy teachers, based on their own perspective, regarding the received continued formation; identify and analyze pedagogical practices for mathematical literacy from the perspective of literacy; and identify the marks of this formation in relation to the teaching and learning of geometry, as a result of the National Pact for Literacy in the Right Age (PNAIC), in 2014. The methodology of this study is qualitative in nature. Data collection was carried out in two schools of a municipal school network in the interior of São Paulo and consisted in the following instruments: questionnaires and semistructured interviews provided by the teachers, and classroom observations of the pedagogical practices of mathematical literacy, containing the perceptions of the researcher, recorded in a field diary. The research on teacher training was based on the contributions of Nóvoa (1999), Tardif and Raymond (2000), Tardif (2000; 2002), Mizukami et al. (2002), Reali (2009), Imbernón (2010) and Candau (2011). In relation to the teaching of mathematics in the initial years, we considered the studies of Nacarato, Mengali and Passos (2011) and Serrazina (2012) and, regarding the teaching and learning of geometry in the initial years, we referred to the research of Lorenzato (1993), Passos (2000), Pavanello (1989, 1993, 2004), Nacarato and Passos (2003, 2014) and Conti (2015). The results, products of the analysis of the answers emitted by the surveyed teachers, show that from the formations of the PNAIC there was an amplification of teaching practices contextualized in the classes of mathematics, fruit of didactic interventions that stimulated the construction of the mathematical knowledge in a significant way considering the teaching role as a key element of this construction of teaching knowledge. The program also developed, in the teachers, a greater awareness on the importance of the development of geometric thinking since the early years of the literacy cycle, expanding the pedagogical possibilities both in the figural and the conceptual elements. The pertinence of this research is based on the social relevance of the theme, seeking a theoretical deepening on the concepts of mathematical literacy in the perspective of geometry literacy, teaching and learning in the literacy cycle, as well as professional teacher development; thus, collaborating to the development processes of the professional's autonomy and consequently aiming at improving the quality of mathematics teaching in the literacy cycle.
Fadiga de ligas de titânio com superfície modificada com nanotubos
(Universidade Federal de São Carlos, 2016-07-29) Bortolan, Carolina Catanio; Oliveira, Nilson Tadeu Camarinho de; https://lattes.cnpq.br/5165925219822865; Bolfarini, Claudemiro; https://lattes.cnpq.br/9231627080617037; https://lattes.cnpq.br/9751895118090780
Among the surface modification techniques to improve the fixation, biocompatibility and corrosion resistance of titanium implants, one of the most recent and promising is the electrochemical anodization in electrolytes with fluoride ions. This technique results in the formation of highly ordered arrays of titanium oxide nanotubes on the surface of these materials. Many researchers evaluated the biological performance of these arrays and obtained satisfactory results, showing that the formation of hydroxyapatite and cellular development are higher after its formation. However, there are no records about the study of fatigue behavior of titanium alloys after this surface treatment; an essential evaluation since the surface conditions of the implants influence the fatigue properties, especially crack nucleation, and the orthopedic implants are subjected to cyclic loads when in service. In this context, the objective of this research was to evaluate the effect of the formation of TiO2 nanotubes, through electrochemical anodization technique in a solution containing fluoride ions, on the fatigue performance of Ti-6Al-4V and Ti-6Al-7Nb alloys, using the staircase method to develop fatigue tests and taking the polished surface condition as reference. SEM, AFM and XRD techniques were applied to characterize the surfaces and to support the fatigue results. The fatigue limit for 5 million cycles, calculated by the statistical method of Dixon-Mood, was maintained for the Ti-6Al-4V alloy (846MPa ± 13 MPa) after the formation of nanotubes on its surface and presented an insignificant reduction in statistical terms for the Ti-6Al-7Nb alloy (846 MPa ± 13 MPa for the polished surface condition and 825MPa ± 11 MPa for the modified surface). The maintenance of fatigue properties of the alloys after electrochemical anodization was mainly attributed to the small scale of the average lengths of the nanotubes and to the existence of a compact oxide layer in contact with the metal substrate (corresponding to the completely closed bottom of nanotubes).
Tris(trimethylsilyl)silane and visible-light irradiation : a new metal- and additive-free photochemical process for the synthesis of indoles and oxindoles
(Universidade Federal de São Carlos, 2016-07-29) Silva, Gustavo Piva da; Paixão, Márcio Weber; https://lattes.cnpq.br/3773908504964104; https://lattes.cnpq.br/0433962216004187
A combined tris(trimethylsilyl)silane and visible-light-promoted intramolecular reductive cyclization protocol for the synthesis of indoles and oxindoles has been developed (Scheme 1).1 This straightforward and efficient protocol shows a broad functional-group tolerance and enables rapid and practical synthesis of functionalized nitrogen-based heterocycles in high/moderate yields under additive and metal-free, mild photochemical conditions. Besides the synthetic developments, the reaction mechanism was also investigated by a set of controlled experiments and UVvisible analyses, as well as kinetic study.2 From these studies, we have concluded that the reaction pathway for this strategy occurs through an Electron Donor-Acceptor (EDA) complex.3 to be continued ...