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Desenvolvimento e caracterização de um banho não-cianetado para a eletrodeposição de ligas de Cu-Sn-Zn: caracterização dos eletrodepósitos
(Universidade Federal de São Carlos, 2014-05-16) Carvalho, Marcos Fernandes de; Carlos, Ivani Aparecida; https://lattes.cnpq.br/1666217445807782; https://lattes.cnpq.br/0922916090536806
The electrodeposition of Cu-Sn-Zn ternary alloys onto AISI 1010 steel from an acid bath with EDTA or NTA salts was investigated, with various proportions of the metal ions in the baths. The concentration of these metals in the baths was determined by factorial design of mixtures with pseudocomponents. From potentiometric titration of these baths were determined regression equations, which led to studies of variance analysis and of surface response. These studies allowed to a pH of stabilization of the Cu-Sn-Zn electrodeposition baths. The Cu-Sn-Zn voltammetric profile showed five cathodic regions: c1, c1 , c2, c3 and c4 (depending on bath composition), and the conditional potentials for the Cu2+, Sn2+ and Zn2+ complexes indicated that these regions were associated, respectively, with reduction of [CuY]2- complex to Cu; [Sn(H2O)6]2+ complex to Sn; [SnY]2- complex to Sn; H2O to H2; and [ZnY]2- complex to Zn. In the presence of NTA, [Cu(NTA)2]4- and [SnNTA]-, [Sn(NTA)2]4-; H2O and [ZnNTA]- and [Zn(NTA)2]4-, respectively, in the regions c1, c2, c3 and c4. Cu-Sn-Zn electrodeposits produced at Ed 1.70 V with qd 3.0 C cm−2 were characterized by EDS, SEM, XRD and confocal optical microscopy (COM) analysis. EDS indicated that a transition potential exists wherein a transition from Cu-Sn binary alloy to Cu-Sn-Zn ternary alloy occurred and, also, that Cu-Sn-Zn co-deposition was normal, preferential or anomalous depending on the bath composition. Moreover, this analyze showed that Zn reduction was facilitated in the presence of NTA. SEM of electrodeposits showed that they were formed by globular and/or irregular crystallites, and, in general, by clusters of crystallites of different sizes dispersed on this layer, depending on the bath composition. COM analysis showed that electrodeposit produced from NTA was more roughness than with EDTA. XRD pattern indicated that the Cu-Sn-Zn electrodeposits, depending on the composition of the baths, presented low crystallinity or crystalline structure with mixture of SnO, η- Cu6Sn5 and Cu5Zn8 phases or pure Sn, η-Cu6Sn5 and Cu5Zn8 phases. Multivariate analysis allows extracting the maximum relevant chemical information from the data.
Estudos de complexos de rutênio (III) e complexos polímero-suportados em reações de hidrogenação e hidroformilação de substratos orgânicos
(Universidade Federal de São Carlos, 2014-05-16) Rodrigues, Claudia; Batista, Alzir Azevedo; https://lattes.cnpq.br/6469642481998660; https://lattes.cnpq.br/8800486122052253
The synthesis and characterization of five ruthenium (III) complexes such as mer-[RuCl3(dppb)(N)], where N = pyridine and 4-substituted derivatives were performed in this work. These complexes were evaluated as catalysts in hydrogenation reactions of cyclohexene and some aldehydes. The obtained results were very satisfactory, presenting values higher than 80% of conversion, in 15 h. These ruthenium (III) complexes, two ruthenium (II) complexes containing CO as ligand and other four precursors, were also tested as catalysts in hydroformylation reactions of alkenes. Considering that is known that hydroformylation reactions can form several sub products, in the best reaction conditions, these catalysts were able to produce up to 61% of product, with only 14% of one sub product. These results were considered satisfactory, due to the possibility to work without additives, promoting a "green" reaction. The ruthenium (III) precursor mer-[RuCl3(dppb)(H2O)], was supported in three different polymers (poly-4-vinylpyridina P4VP, chitosan QT e aminopropyl silica APS). The catalytic activities of these polymersupported compounds were tested in hydrogenation of cyclohexene. Due to the possibility to separate the solid catalyst by filtration and easily isolate the product, the results showing 70% of conversion were considered satisfactory and "green". The ruthenium complex chitosan-supported was tested on the formation of a film, which was used to modify a glassy carbon electrode (GCE). This modified GCE was tested as an electrochemical sensor for the detection and quantification of drugs (acetaminophen and sildenafil citrate). The electrode showed a great electrochemical response and high sensitivity when compared to an unmodified glassy carbon electrode and a glassy carbon electrode chitosan modified. The polymeric film was stable to degradation in acids electrolytes showing a linear response evaluated in 1,25 x 10-5 a 4,99 x 10-4 mol L-1 concentration interval.
O primeiro Manoel de Barros e o aprendizado poético
(Universidade Federal de São Carlos, 2014-05-16) Ferrari, Viviane de Cássia Duarte; Marques, Wilton José; https://lattes.cnpq.br/5763590592946918; https://lattes.cnpq.br/6835842015001036
The problem articulated in this work is to understand how the mato-grossense poet Manoel de Barros has been produced a modern poetry since the start of his career, when he had published the books Poemas concebidos sem pecado (1937) e Face imóvel (1942). To identify such a question, it will support, first in an overview of the barreano themes and stile, following, it will be done interpretative analysis of some poems from both books, in order to see if the modern aspects presented as marks on his poetry have already appeared since the beginning of his writings and if changes occurred in these traits throughout his literary creations. Thus, this research will verify the guiding-up elements of his first poetry, in order to establish relations between his initial poetic project and the rest of his works. This interpretative and comparative approach will contribute to the understanding and affinities of his unconventional lyrical. As it was seen here, both the recurrence of certain themes and some peculiarities of barreano style, it can show various signs of modernity which, in turn, helped to single out his poetics.