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Desenvolvimento de membranas poliméricas para sistemas de remediação de íons metálicos pesados em soluções aquosas
(Universidade Federal de São Carlos, 2019-07-30) Bosquetti, João César; Silva, Caio Marcio Paranhos da; https://lattes.cnpq.br/7793686262868668; https://lattes.cnpq.br/1261532663035588
The planet Earth is flooded with about 1.4 billion km3 of water, meaning that almost 71% of its surface is covered by water. However, only about 0.77% of this volume is accessible in the form of fresh water presented in rivers, lakes, groundwater and the atmosphere. Meanwhile of this small amount, about 12.8% have been contaminated or poorly used by man. This contamination is usually caused by percolation, whether of spot or diffuse, such as accidents in reservoir tanks, discharge of sewage sludge, improper use of fertilizers and sanitary waste, as well as accumulation of waste on riverbanks, has been increasing in last years. Contamination of water by heavy metals is perhaps the most worrying of contaminations, since they are highly toxic, cumulative and difficult to mitigate. In this sense, considering the amount of residues generated in the Laboratory of Teaching of Inorganic Chemistry, contaminated with heavy metals of high toxicity, it was thought of a way to reduce the amount of ions of some metals, especially lead (Pb), cádmium (Cd) and Mercury (Hg), employing low cost and easy to obtain polymer membranes to minimize the amount of waste sent to the Department of Waste Management (DeGR) of the Federal University of São Carlos - UFSCar. The aim is to minimize these ions present in the solutions, bringing the possibility of reuse of previously contaminated water or to discard it in the common domestic sewage, depending on the efficiency generated by the adsorption yield of these membranes in removing these inconvenient ions from the aqueous solution of discard. Basically, high density polyethylene (HDPE) membranes were modified with polyethylene with maleic anhydride (PE-g-AM), loaded with sodium aluminate and incorporated with aluminum phosphate (AlPO4). Membranes were synthesized whose proportions of these materials were varied with the purpose of verifying which of them would give the best yield. In this aspect, it was observed that all the membranes and blends synthesized showed heterogeneity in their constitution, resulting in regions with higher and lower yield in the same membrane. However, the blends loaded and incorporated with aluminum phosphates had a slightly higher adsorption efficiency compared to ions dispersed in the solution.
Cônicas: uma prática escolar
(Universidade Federal de São Carlos, 2019-07-30) Puppin, Maurício; Bertoncello, Luciene Nogueira; https://lattes.cnpq.br/8028970771846775; https://lattes.cnpq.br/7328458570509096
Based on the protagonism of the learner, this work aims to assist the teacher of mathematics of High School, in the teaching of Analytical Geometry, with a practical approach to facilitate the student's understanding of Conics, with emphasis on ellipse. By the use of free software Geogebra, the student can observe the translation of the curve in the plane and identify in its equation, the differences between the positions: horizontal and vertical, making learning dynamic and more effective.
Mechanical properties and metallurgical characterization of AA6082-T6 alloy welded by refill friction stir spot welding
(Universidade Federal de São Carlos, 2019-07-30) Silva, Bruno Hessel; Zepon, Guilherme; https://lattes.cnpq.br/7924187202036614; Bolfarini, Claudemiro; https://lattes.cnpq.br/9231627080617037; https://lattes.cnpq.br/6735270859581901
The efforts to produce automobiles with intense use of aluminum alloys is growing and the 6XXX series of aluminum alloys are important for this scenario. However, the current joining technologies applied in these alloys present limitations regarding weld uniformity, energy input and production costs. Refill Friction Stir Spot Welding (RFSSW) is a solid-state welding technique with potential to surpass these limitations. In order to validate this technique in automotive applications, issues must be addressed such as obtaining mechanical properties standards; determining the effect of process parameters on weld structure and properties; optimizing cost-efficiency factors and others. In this work the application of RFSSW in the AA6082-T6 alloy was studied focusing on: (i) the effect of process parameters on weld structure and mechanical properties; (ii) understanding of fracture behavior of the welds under static and cyclic load; and (iii) the influence of Bake Hardening treatment on the weld structure and properties. Optimized process parameters set with suitable welding time for industry applications were obtained using statistical analysis maximizing static mechanical properties. Macro/microstructural analysis were carried out and demonstrated that the Plunge Depth parameter has the most relevant influence on weld strength and fracture behavior due to its effect in hook shape formation, which is an intrinsic feature in RFSSW welds. Hardness and thermal characterization helped to understand the effect of Bake Hardening on reprecipitation and overaging process in different weld regions and, consequently, on the mechanical properties and fracture behavior of the welds. Using Weibull Statistical analysis, L-N fatigue curves were obtained and demonstrated that, regardless the hook shape, the curves presented similar trend and fatigue limit close to 12% of the maximum Shear Load. Finally, based on fatigue fracture surface characterization, it was found that the hook shape configuration has a relevant effect on fracture behavior only for low-cycle load conditions.
Existence and multiplicity of solutions for problems involving the Dirac operator
(Universidade Federal de São Carlos, 2019-07-30) Somavilla, Fernanda; Miyagaki, Olimpio Hiroshi; https://lattes.cnpq.br/2646698407526867; Paiva, Francisco Odair Vieira de; https://lattes.cnpq.br/2889322093175193; https://lattes.cnpq.br/0280451137694299
In this thesis, we study equations that involving the Dirac operator and which have the form $-i \alpha \cdot \nabla u + a \beta u + M(x)u = F_{u}(x,u), em \mathbb{R}^{3},$ where $\alpha = (\alpha_1, \alpha_2, \alpha_3),$ with $\alpha_{j}$ and $\beta$ are complex matrices 4x4, j = 1, 2, 3 and a>0.Using variational methods and elements from critical point theory for strongly indefinite problems we obtain existence and multiplicity results of solutions $u:R^{3} \rightarrow C^{4}$ under different sets of hypothesis about the potential M and the nonlinearity F: Firstly, we consider a problem with nonperiodic potential and concave-convex type nonlinearity, nonperiodic, which contain weight functions that can present signal change. Next, using the generalized Nehari manifold, we study problems in which nonlinearity satisfies weak monotonicity conditions and may relate to the potential function. Among such problems,we consider a periodic case and, due to the assumptions, in order to obtain the multiplicity results we use the Clarke's subdifferential and Krasnoselskii genus. Finally, we approach a problem with nonlinearity asymptotically linear at infinity and matrix potential. In this case, the potential is described by a sum of a non-positive suitable matrix potential and a diagonal matrix whose elements are function in some $L^{\sigma}, \sigma >1,$ which can change signal.
Proposição de modelos de regressão para previsão de propriedades de tintas da cadeia produtiva da indústria gráfica
(Universidade Federal de São Carlos, 2019-07-30) Oshiro, Eduardo Hideki; Pereira Filho, Edenir Rodrigues; https://lattes.cnpq.br/3394181280355442; https://lattes.cnpq.br/9220595873630980
Quality control of inks is very important during and after the manufacturing process and is also meaningful in the consumer industries or paint applicators. For this reason, an opportunity was noticed for the development of a method of determining the properties of a solvent based ink of the printing industry. The analytical method proposed was through the infrared spectroscopy and multivariate calibration. The ink used in the project is employed in the rotogravure printing process. This process is used for printing many quantities of printing materials at high speed. It is usually applied in the production of packaging and magazines. The fallowing quality control parameters: viscosity, density and solids of black and white inks were analyzed by the reference methods according ASTM standards. Prediction models for these parameters were developed through Fourier transform infrared spectrometer with attenuated total reflectance sampling accessory (FT-MID-IR ATR) and the multivariate calibration, the partial least squares regression (PLSR). Pre-treatments in the spectra (1st and 2nd derivatives with Savitzky-Golay) were tested and also the models with spectra without treatments. The best results were found according to the parameter and ink tested, for viscosity of black ink the model without treatment was used, for viscosity of white ink the 2nd derivative was used. And for density and solids, unique models were developed to be used in black and white inks, the 1st derivative was the best option in both cases. The best models and latent variables were selected through the evaluation of the root mean square errors values of calibration, validation and cross validation (RMSEC, RMSEV and RMSECV), as well as the determination coefficients (R2) obtained from predicted x reference results. The set of validation samples showed a good quality of the results, according to the p-value. Although there are many articles related to prediction of chemical physics characteristics of fuels and derivatives using infrared spectroscopy and the chemometric tool, few studies with this approach to inks have been found in the literature. The following advantages of the developed method can be highlighted: low sample volume (0.1 mL - 1 drop), rapid analysis (2 minutes) and the low waste amount.