Desenvolvimento de material BaCexPr1-xO3 (0 ≤ X ≤ 1) com estrutura perovskita para oxidação catalítica do CO a CO2 em reator de leito fixo

Barium Cerate (BaCeO3) is perovskite type structure of ABO3, wherein A and B are metal cations. These materials, or doped, have been studied by having characteristics that make them promising for the application in fuel cells solid oxide, hydrogen and oxygen permeation, as catalysts, etc .. However, as the ceramic materials mixed conductivity have been produced by different synthesis methods, some conditions directly influence the final properties, one of the most important doping Site B, which may have direct influence on the crystallite size, which in turn directly influences their catalytic activity. In this study, perovskite-type (BaCexO3) had cerium gradually replaced by praseodymium to obtain ternary type materials BaCexPr1-xO3 and BaPrO3 binaries. These materials were synthesized by EDTA/Citrate complexing method and the material characterized via XRD, SEM and BET for the identification of their structure, morphology and surface area. Moreover were performed on all materials, catalytic test in a fixed bed reactor for the identification of that person responsible for complete conversion of CO to CO2 at low operating temperature, which step can be used as the subsequent production of synthesis gas (CO + H2) from methane oxidation. In the present work the crystalline phase having the orthorhombic structure was obtained for all compositions, with a morphology consisting of agglomerated particles being more pronounced with increasing praseodymium in the crystal structure. The average crystal size was between 100 nm and 142,2 nm. The surface areas were 2,62 m²g-1 for the BaCeO3 composition, 3,03 m²g-1 to BaCe0,5Pr0,5O3 composition and 2,37 m²g-1 to BaPrO3 composition. Regarding the catalytic tests, we can conclude that the optimal flow reactor operation was 50 ml / min and the composition regarding the maximum rate of conversion to the lowest temperature was BaCeO3 to 400° C. Meanwhile, there was found that the partially replaced by praseodymium, cerium, there was a decrease in the catalytic activity of the material.

Desenvolvimento da célula base de microestruturas periódicas de compósitos sob otimização topológica

This thesis develops a new technique for composite microstructures projects by the Topology Optimization process, in order to maximize rigidity, making use of Deformation Energy Method and using a refining scheme h-adaptative to obtain a better defining the topological contours of the microstructure. This is done by distributing materials optimally in a region of pre-established project named as Cell Base. In this paper, the Finite Element Method is used to describe the field and for government equation solution. The mesh is refined iteratively refining so that the Finite Element Mesh is made on all the elements which represent solid materials, and all empty elements containing at least one node in a solid material region. The Finite Element Method chosen for the model is the linear triangular three nodes. As for the resolution of the nonlinear programming problem with constraints we were used Augmented Lagrangian method, and a minimization algorithm based on the direction of the Quasi-Newton type and Armijo-Wolfe conditions assisting in the lowering process. The Cell Base that represents the composite is found from the equivalence between a fictional material and a preescribe material, distributed optimally in the project area. The use of the strain energy method is justified for providing a lower computational cost due to a simpler formulation than traditional homogenization method. The results are presented prescription with change, in displacement with change, in volume restriction and from various initial values of relative densities.

Estudo da molhabilidade de superfícies de parafina e aço inoxidável por soluções de tensoativos não iônicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da deposição de filmes finos de BaTi(1-X)Zr(X)O3 por meio de planejamento Box-Behnken

Ferroelectric ceramics with perovskite structure (ABO3) are widely used in solid state memories (FeRAM’s and DRAM's) as well as multilayered capacitors, especially as a thin films. When doped with zirconium ions, BaTiO3-based materials form a solid solution known as barium zirconate titanate (BaTi1-xZrxO3). Also called BZT, this material can undergo significant changes in their electrical properties for a small variation of zirconium content in the crystal lattice. The present work is the study of the effects of deposition parameters of BaTi0,75Zr0,25O3 thin films by spin-coating method on their morphology and physical properties, through an experimental design of the Box-Behnken type. The resin used in the process has been synthesized by the polymeric precursor method (Pechini) and subsequently split into three portions each of which has its viscosity adjusted to 10, 20 and 30 mPa∙s by means of a rotary viscometer. The resins were then deposited on Pt/Ti/SiO2/Si substrates by spin-coating method on 15 different combinations of viscosity, spin speed (3000, 5500 and 8000 rpm) and the number of deposited layers (5, 8 and 11 layers) and then calcined at 800 ° C for 1 h. The phase composition of the films was analyzed by X-ray diffraction (XRD) and indexed with the JCPDS 36-0019. Surface morphology and grain size were observed by atomic force microscopy (AFM) indicating uniform films and average grain size around 40 nm. Images of the cross section of the films were obtained by scanning electron microscopy field emission (SEM-FEG), indicating very uniform thicknesses ranging from 140-700 nm between samples. Capacitance measurements were performed at room temperature using an impedance analyzer. The films presented dielectric constant values of 55-305 at 100kHz and low dielectric loss. The design indicated no significant interaction effects between the deposition parameters on the thickness of the films. The response surface methodology enabled better observes the simultaneous effect of variables.

Materiais bionanocompósitos a base de argilominerais e hidróxidos duplos lamelares como sistemas de liberação de fármacos

Bionanocomposites systems clay base (montmorillonite and sepiolite), layered double hidroxides and biopolymers (carboxymethylcellulose and zein) were evaluated as topical delivery systems with antibacterial activity and as oral delivery systems. For this study, neomycin, a topical antibiotic, indicated mainly for open wound infections. The drug amoxicillin, an antibiotic indicated mainly for throat infections, were also used in this study. Both antibiotics were used as model drugs. Initially, drugs were incorporated directly into the biopolymer matrix, comprising the combination of carboxymethylcellulos and zein, being conformed as movies and balls and evaluated for their antibacterial activity and controlled release simulating gastrointestinal fluids. Moreover, hybrids materials have been prepared where the neomycin drug was incorporated into the lamellar inorganic solids, such as montmorillonite by ion exchange reaction, and the fibrous type, such as sepiolite by adsorption in aqueous solution. But the drug amoxicillin was incorporated into layered double hydroxides by anion exchange and montmorillonite by cation exchange. The resulting hybrids were in turn combined with the biopolymer matrix yielding bionanocomposites shaped materials such as films were tested for their antibacterial activity, and the shaped materials beads were tested for their release in the gastrointestinal fluids. Through the analysis of various physico-chemical techniques, we observed the interactions between the studied materials, the formation of hybrids materials, obtaining the bionanocomposites materials and material efficiency when applied in controlled release of drugs both topical and use oral mainly influenced by the presence of zein, are promising as topical delivery systems and oral drugs.

Programas de verdade, "mundos de crença": o verdadeiro segundo Paul Vayne

This study comes to reflect on the place of truth in everyday human experience. The notion of truth, expressed in different ways, in different systems of thought, cultural and historical, reveals the non-uniformity of their meaning and the arbitrary grouping under one name, truth. Given this fact, of so many beliefs taken as absolute, we ask with the historian Jean Marie Paul Veyne, if the truth is only one, or many called by a word namesake. If, through their ideas, men cannot access a definitely solid knowledge, unchanging and jaunty interference of the human condition (as their interests and affections), then in what sense it can claim a greater and exclusivist truth? Assuming the impossibility of apprehension of the reality of this type, Paul Veyne develops the notion of truth programs, referential beliefs assumed as cartographies that direct action and thought. He defends thus the idea of heterogeneity and plurality, as irreducible elements of human truths. On the one hand there is in society a plurality of truth programs, on the other there is a plurality of beliefs that is inside man. That is, in the way they believe the men also shows plural, because they believe in more than one program and counter programs. The thought of Paul Veyne is nonetheless a form of skepticism directed at all supposedly absolute and universal anthropological truths, because depending on the belief system studied and the specific moment in its history, a set of rules is established to distinguish the true from the false.

Análise da imunoexpressão de Oct- 4 e C44 em lesões odontogênicas epiteliais benignas

benign epithelial odontogenic lesions are great clinical importance entities that develop in the jaws from the tissues that form teeth. It has been shown that in benign and malignant tumors, are present in a large number of tumor stem cells, which has great implications in the development of these lesions. Oct-4 and CD44 have been demos as important markers for tumoral stem cells. The objective of this study was to identify epithelial cells expressing stem cell markers by immunohistochemical expression of Oct-4 and CD44 in a series of cases of benign epithelial odontogenic lesions. The sample was comprised of 20 cases of odontogenic keratocyst (OKC), 20 cases of solid/multicystic ameloblastoma and 20 cases of adenomatoid odontogenic tumor (AOT). The expression of Oct-4 and CD44 was evaluated in epithelial lesions using the percentage of positive cells (PP) and the intensity of expression (IE), being realized the sum of these scores, resulting in Total Immunostaining Score (TIS) ranging 0 to 7. The results were submitted to the appropriate statistical test (nonparametric Kruskal-Wallis and Spearman correlation coefficient). All cases were positive for both markers and most showed high expression of both markers. The analysis of Oct-4 expression revealed no statistically significant differences (p = 0.406) among the studied lesions. Regarding the CD44 expression, there was a statistically significant difference between the cases of ameloblastoma and TOA in relation to the CCO, with the latter show more cases in the score 7 (p = 0.034). In the correlation analysis of the immunoreactivity of both markers in the three lesions studied, there was no statistically significant correlation. The results of this study identified the presence of cells with stemness characteristics arranged at various sites in the epithelial component of the studied lesions suggesting their possible role in the histogenesis and differentiation in benign epithelial odontogenic lesions, thus contributing to the development of these lesions.

Análise da imunoexpressão de Oct- 4 e C44 em lesões odontogênicas epiteliais benignas

benign epithelial odontogenic lesions are great clinical importance entities that develop in the jaws from the tissues that form teeth. It has been shown that in benign and malignant tumors, are present in a large number of tumor stem cells, which has great implications in the development of these lesions. Oct-4 and CD44 have been demos as important markers for tumoral stem cells. The objective of this study was to identify epithelial cells expressing stem cell markers by immunohistochemical expression of Oct-4 and CD44 in a series of cases of benign epithelial odontogenic lesions. The sample was comprised of 20 cases of odontogenic keratocyst (OKC), 20 cases of solid/multicystic ameloblastoma and 20 cases of adenomatoid odontogenic tumor (AOT). The expression of Oct-4 and CD44 was evaluated in epithelial lesions using the percentage of positive cells (PP) and the intensity of expression (IE), being realized the sum of these scores, resulting in Total Immunostaining Score (TIS) ranging 0 to 7. The results were submitted to the appropriate statistical test (nonparametric Kruskal-Wallis and Spearman correlation coefficient). All cases were positive for both markers and most showed high expression of both markers. The analysis of Oct-4 expression revealed no statistically significant differences (p = 0.406) among the studied lesions. Regarding the CD44 expression, there was a statistically significant difference between the cases of ameloblastoma and TOA in relation to the CCO, with the latter show more cases in the score 7 (p = 0.034). In the correlation analysis of the immunoreactivity of both markers in the three lesions studied, there was no statistically significant correlation. The results of this study identified the presence of cells with stemness characteristics arranged at various sites in the epithelial component of the studied lesions suggesting their possible role in the histogenesis and differentiation in benign epithelial odontogenic lesions, thus contributing to the development of these lesions.

Modelagem multiescala de fenômenos eletrocinéticos em meios porosos carregados eletricamente: aplicação a meios porosos argilosos

In this master thesis, we propose a multiscale mathematical and computational model for electrokinetic phenomena in porous media electrically charged. We consider a porous medium rigid and incompressible saturated by an electrolyte solution containing four monovalent ionic solutes completely diluted in the aqueous solvent. Initially we developed the modeling electrical double layer how objective to compute the electrical potential, surface density of electrical charges and considering two chemical reactions, we propose a 2-pK model for calculating the chemical adsorption occurring in the domain of electrical double layer. Having the nanoscopic model, we deduce a model in the microscale, where the electrochemical adsorption of ions, protonation/ deprotonation reactions and zeta potential obtained in the nanoscale, are incorporated through the conditions of interface uid/solid of the Stokes problem and transportation of ions, modeled by equations of Nernst-Planck. Using the homogenization technique of periodic structures, we develop a model in macroscopic scale with respective cells problems for the e ective macroscopic parameters of equations. Finally, we propose several numerical simulations of the multiscale model for uid ow and transport of reactive ionic solute in a saturated aqueous solution of kaolinite. Using nanoscopic model we propose some numerical simulations of electrochemical adsorption phenomena in the electrical double layer. Making use of the nite element method discretize the macroscopic model and propose some numerical simulations in basic and acid system aiming to quantify the transport of ionic solutes in porous media electrically charged.

Modelagem multiescala de fenômenos eletrocinéticos em meios porosos carregados eletricamente: aplicação a meios porosos argilosos

In this master thesis, we propose a multiscale mathematical and computational model for electrokinetic phenomena in porous media electrically charged. We consider a porous medium rigid and incompressible saturated by an electrolyte solution containing four monovalent ionic solutes completely diluted in the aqueous solvent. Initially we developed the modeling electrical double layer how objective to compute the electrical potential, surface density of electrical charges and considering two chemical reactions, we propose a 2-pK model for calculating the chemical adsorption occurring in the domain of electrical double layer. Having the nanoscopic model, we deduce a model in the microscale, where the electrochemical adsorption of ions, protonation/ deprotonation reactions and zeta potential obtained in the nanoscale, are incorporated through the conditions of interface uid/solid of the Stokes problem and transportation of ions, modeled by equations of Nernst-Planck. Using the homogenization technique of periodic structures, we develop a model in macroscopic scale with respective cells problems for the e ective macroscopic parameters of equations. Finally, we propose several numerical simulations of the multiscale model for uid ow and transport of reactive ionic solute in a saturated aqueous solution of kaolinite. Using nanoscopic model we propose some numerical simulations of electrochemical adsorption phenomena in the electrical double layer. Making use of the nite element method discretize the macroscopic model and propose some numerical simulations in basic and acid system aiming to quantify the transport of ionic solutes in porous media electrically charged.

Protótipo de rastreador solar de um eixo baseado em microcontrolador

The increase in the efficiency of photo-voltaic systems has been the object of various studies the past few years. One possible way to increase the power extracted by a photovoltaic panel is the solar tracking, performing its movement in order to follow the sun’s path. One way to activate the tracking system is using an electric induction motor, which should have sufficient torque and low speed, ensuring tracking accuracy. With the use of voltage source inverters and logic devices that generate the appropriate switching is possible to obtain the torque and speed required for the system to operate. This paper proposes the implementation of a angular position sensor and a driver to be applied in solar tracker built at a Power Electronics and Renewable Energies Laboratory, located in UFRN. The speed variation of the motor is performed via a voltage source inverter whose PWM command to actuate their keys will be implemented in an FPGA (Field Programmable Gate Array) device and a TM4C microcontroller. A platform test with an AC induction machine of 1.5 CV was assembled for the comparative testing. The angular position sensor of the panel is implemented in a ATMega328 microcontroller coupled to an accelerometer, commanded by an Arduino prototyping board. The solar position is also calculated by the microcontroller from the geographic coordinates of the site where it was placed, and the local time and date obtained from an RTC (Real-Time Clock) device. A prototype of a solar tracker polar axis moved by a DC motor was assembled to certify the operation of the sensor and to check the tracking efficiency.