Análise de sedimentos associados à atividade de perfuração na plataforma continental externa, Bacia Potiguar - Brasil

This study was developed in an area located on the outer shelf in the Potiguar Basin, Brazilian equatorial margin; this tropical shelf represents a modern, highly dynamic mixed carbonate-siliciclastic system. Field sampling was carried out during 3 cruises surrounding a shallow-water exploratory well to compare sediment properties of the seafloor, including grainsize, texture, mineral composition, carbonate content, and organic matter. Cruise 1 (C1) was carried prior to drilling, while Cruise 2(C2) and 3 (C3) respectivelly 3 and 12 months after drilling. The sample grid used had 16 stations located along 4 radials from 50 m the well up to a distance of 500 m. Sediments were analyzed in the first 0-2 cm, and 0-10 cm layers. The results show that sedimentary cover around the well is poor to very poorly sorted, with the particle size predominantly in the medium to coarse sand fraction, followed by gravel and mud. The content of calcium carbonate is greater than 96%, associated to bioclastic sediments, and the content of organic matter is less than 12%. Only minor sedimentological variations occured in the area affected by drilling operations. Mainly observed during the second cruise, in terms of a change in grain size distribution associated to an increase in siliciclastic content, This impact occurred in the most surficial sediment (0-2 cm), in the radial closest to the well (50 m), and could suggest the effects of drilling. However, in the third cruise, one year after drilling, the sediments return to show the same characteristics as in the first cruise. These results show no significant sedimentological variations due to drilling activity, and indicate that ocean dynamics in this area was high enough to recover the environment original characteristics.

Análise de sedimentos associados à atividade de perfuração na plataforma continental externa, Bacia Potiguar - Brasil

This study was developed in an area located on the outer shelf in the Potiguar Basin, Brazilian equatorial margin; this tropical shelf represents a modern, highly dynamic mixed carbonate-siliciclastic system. Field sampling was carried out during 3 cruises surrounding a shallow-water exploratory well to compare sediment properties of the seafloor, including grainsize, texture, mineral composition, carbonate content, and organic matter. Cruise 1 (C1) was carried prior to drilling, while Cruise 2(C2) and 3 (C3) respectivelly 3 and 12 months after drilling. The sample grid used had 16 stations located along 4 radials from 50 m the well up to a distance of 500 m. Sediments were analyzed in the first 0-2 cm, and 0-10 cm layers. The results show that sedimentary cover around the well is poor to very poorly sorted, with the particle size predominantly in the medium to coarse sand fraction, followed by gravel and mud. The content of calcium carbonate is greater than 96%, associated to bioclastic sediments, and the content of organic matter is less than 12%. Only minor sedimentological variations occured in the area affected by drilling operations. Mainly observed during the second cruise, in terms of a change in grain size distribution associated to an increase in siliciclastic content, This impact occurred in the most surficial sediment (0-2 cm), in the radial closest to the well (50 m), and could suggest the effects of drilling. However, in the third cruise, one year after drilling, the sediments return to show the same characteristics as in the first cruise. These results show no significant sedimentological variations due to drilling activity, and indicate that ocean dynamics in this area was high enough to recover the environment original characteristics.

Influência da interação dipolar nas fases magnéticas de nanopartículas esféricas com estrutura núcleo@camada

Bi-magnetic core@shell nanoparticle has attracted attention several researchers because great applicability that they offer. The possibility of combining different functionalities of magnetic materials make them a key piece in many areas as in data processing permanent magnets and biomagnetics sistems. These nanoparticles are controlled by intrinsic properties of the core and shell materials as well as the interactions between them, besides size and geometry effects. Thus, it was developed in this thesis a theoretical study about dipolar interaction contribution between materials different magnetic properties in bi-magnetic core@shell nanoparticles conventional spherical geometry. The materials were analyzed CoFe2O4, MnFe2O4 e CoFe2 in various combinations and sizes. The results show that the impact of the core dipole field in the shell cause reverse magnetization early its, before of the core, in nanoparticle of CoFe2O4(22nm)@CoFe2(2nm), thereby causing a decrease coercivity field of 65% in comparection with simple nanoparticle of CoFe2O4 (HC=13.6 KOe) of same diameter. The large core anisotropy in conventional nanoparticle makes it the a stable dipolar field source in the shell, that varies length scale of the order of the core radius. Furthermore, the impact of dipolar field is greatly enhanced by the geometrical constraints and by magnetics properties of both core@shell materials. In systems with core coated with a thin shell of thickness less than the exchange length, the interaction interface can hold reversal the shell occurring an uniform magnetization reversal, however this effect only is relevant on systems where the dipole field effects is weak compared with the exchange interaction.

Influência da interação dipolar nas fases magnéticas de nanopartículas esféricas com estrutura núcleo@camada

Bi-magnetic core@shell nanoparticle has attracted attention several researchers because great applicability that they offer. The possibility of combining different functionalities of magnetic materials make them a key piece in many areas as in data processing permanent magnets and biomagnetics sistems. These nanoparticles are controlled by intrinsic properties of the core and shell materials as well as the interactions between them, besides size and geometry effects. Thus, it was developed in this thesis a theoretical study about dipolar interaction contribution between materials different magnetic properties in bi-magnetic core@shell nanoparticles conventional spherical geometry. The materials were analyzed CoFe2O4, MnFe2O4 e CoFe2 in various combinations and sizes. The results show that the impact of the core dipole field in the shell cause reverse magnetization early its, before of the core, in nanoparticle of CoFe2O4(22nm)@CoFe2(2nm), thereby causing a decrease coercivity field of 65% in comparection with simple nanoparticle of CoFe2O4 (HC=13.6 KOe) of same diameter. The large core anisotropy in conventional nanoparticle makes it the a stable dipolar field source in the shell, that varies length scale of the order of the core radius. Furthermore, the impact of dipolar field is greatly enhanced by the geometrical constraints and by magnetics properties of both core@shell materials. In systems with core coated with a thin shell of thickness less than the exchange length, the interaction interface can hold reversal the shell occurring an uniform magnetization reversal, however this effect only is relevant on systems where the dipole field effects is weak compared with the exchange interaction.

Síntese, caracterização e estudo da associação em meio aquoso de copolímeros responsivos de carboximetilcelulose-g-Jeffamine®

This thesis presents the synthesis, characterization and study of the associative behaviour in aqueous media of new responsive graft copolymers, based on carboxymethylcellulose as the water-soluble backbone and Jeffamine® M-2070 e Jeffamine® M-600 (commercial polyetheramines) as the thermoresponsive grafts with high cloud point temperatures in water. The synthesis was performed on aqueous medium, by using 1-ethyl-3- (3-(dimethylamino)-propyl)carbodiimide hydrochloride and N-hydroxysuccinimide as activators of the reaction between carboxylategroupsfrom carboxymethylcellulose and amino groups from polyetheramines. The grafting reaction was confirmed by infrared spectroscopy and the grafting percentage by 1H NMR. The molar mass of the polyetheramines was determined by 1H NMR, whereas the molar mass of CMC and graft copolymers was determined by static light scattering. The salt effect on the association behaviour of the copolymers was evaluated in different aqueous media (Milli-Q water, 0.5M NaCl, 0.5M K2CO3 and synthetic sea water), at different temperatures, through UV-vis, rheology and dynamic light scattering. None of the copolymers solutions, at 5 g/L, turned turbid in Milli-Q water when heated from 25 to 95 °C, probably because of the increase in hydrophibicity promoted by CMC backbone. However, they became turbid in the presence of salts, due to the salting out effect, where the lowest cloud point was observed in 0.5M K2CO3, which was attributed to the highest ionic strength in water, combined to the ability of CO3 2- to decrease polymer-solvents interactions. The hydrodynamic radius and apparent viscosity of the copolymers in aqueous medium changed as a function of salts dissolved in the medium, temperature and copolymer composition. Thermothickening behaviour was observed in 0.5M K2CO3 when the temperature was raised from 25 to 60°C. This performance can be attributed to intermolecular associations as a physical network, since the temperature is above the cloud point of the copolymers in this solvent.

Análise fractal da vasculatura retínica: métodos de segmentação e de cálculo dimensional

Embora tenha sido proposto que a vasculatura retínica apresenta estrutura fractal, nenhuma padronização do método de segmentação ou do método de cálculo das dimensões fractais foi realizada. Este estudo objetivou determinar se a estimação das dimensões fractais da vasculatura retínica é dependente dos métodos de segmentação vascular e dos métodos de cálculo de dimensão. Métodos: Dez imagens retinográficas foram segmentadas para extrair suas árvores vasculares por quatro métodos computacionais (“multithreshold”, “scale-space”, “pixel classification” e “ridge based detection”). Suas dimensões fractais de “informação”, de “massa-raio” e “por contagem de caixas” foram então calculadas e comparadas com as dimensões das mesmas árvores vasculares, quando obtidas pela segmentação manual (padrão áureo). Resultados: As médias das dimensões fractais variaram através dos grupos de diferentes métodos de segmentação, de 1,39 a 1,47 para a dimensão por contagem de caixas, de 1,47 a 1,52 para a dimensão de informação e de 1,48 a 1,57 para a dimensão de massa-raio. A utilização de diferentes métodos computacionais de segmentação vascular, bem como de diferentes métodos de cálculo de dimensão, introduziu diferença estatisticamente significativa nos valores das dimensões fractais das árvores vasculares. Conclusão: A estimação das dimensões fractais da vasculatura retínica foi dependente tanto dos métodos de segmentação vascular, quanto dos métodos de cálculo de dimensão utilizados

Síntese e caracterização de NiO-CGO para anodo e eletrólitos sólidos e base de Céria para SOFC

The direct use of natural gas makes the Solid Oxide Fuel Cell (SOFC) potentially more competitive with the current energy conversions technologies. The Intermediate Temperature SOFC (IT-SOFC) offer several advantages over the High Temperature SOFC (HT-SOFC), which includes better thermal compatibility among components, fast start with lower energy consumption, manufacture and operation cost reduction. The CeO2 based materials are alternatives to the Yttria Stabilized Zirconia (YSZ) to application in SOFC, as they have higher ionic conductivity and less ohmic losses comparing to YSZ, and they can operate at lower temperatures (500-800°C). Ceria has been doped with a variety of cations, although, the Gd3+ has the ionic radius closest to the ideal one to form solid solution. These electrolytes based in ceria require special electrodes with a higher performance and chemical and termomechanical compatibility. In this work compounds of gadolinia-doped ceria, Ce1-xGdxO2-δ (x = 0,1; 0,2 and 0,3), used as electrolytes, were synthesized by polymeric precursors method, Pechini, as well as the composite material NiO - Ce0,9Gd0,1O1,95, used as anode, also attained by oxide mixture method, mixturing the powders of the both phases calcinated already. The materials were characterized by X ray diffraction, dilatometry and scanning electronic microscopy. The refinement of the diffraction data indicated that all the Ce1-xGdxO2-δ powders were crystallized in a unique cubic phase with fluorite structure, and the composite synthesized by Pechini method produced smaller crystallite size in comparison with the same material attained by oxide mixture method. All the produced powders had nanometric characteristics. The composite produced by Pechini method has microstructural characteristics that can increase the triple phase boundaries (TPB) in the anode, improving the cell efficiency, as well as reducing the mass transport mechanism effect that provokes anode degradation

Estudos e propriedades mecânicas de um novo tipo de bloco cerâmico híbrido para edificações em alvenarias estruturais

This dissertation presents a hybrid ceramic block the use of which reside in the buildings executed with walls. Initially, we conducted a survey on the requirements and / or norms prevailing in Brazil about structural ceramic blocks, making use of the experiences in other countries. This work seeks new materials and / or products in order to maintain or increase the compressive strength of the ceramic blocks, without neglecting the other properties. Then was collected materials (clay and crushed powder) and an approach on the characterization, through fluorescence, Mineralogy, vitrification curve and characterization of these materials used in the manufacture of the blocks by Ray Diffraction "X" and SEM. Subsequently it was made, numbered and measured dimensions of about 150 bodies of the test piece (hybrid ceramic blocks in small sizes) with varying percentages of 0%, 5%, 10% and 15% substitution of crushed clay powder. After sintering of the bodies of the test piece at temperatures of 900oC, 1000oC 1100oC and with a heating rate of 5oC/minuto and level of 1 hour, the samples were submitted to the tests (compressive strength and water absorption) and calculated their retractions, which were subsequently carried out the analysis of the results according to the criteria and parameters required by Brazilian legislation and standards in force

Degradação do PMMA através da reação despolimerização uitlizando catalisadores de óxidos mistos

In this work, mixed oxides were synthesized by two methods: polymeric precursor and gel-combustion. The oxides, Niquelate of Lanthanum, Cobaltate of Lanthanum and Cuprate of Lanthanum were synthesized by the polymeric precursor method, and treated at 300 º C for 2 hours, calcined at 800 º C for 6h in air atmosphere. In gel-combustion method were produced and oxides using urea and citric acid as fuel, forming for each fuel the following oxides Ferrate of Lanthanum, Cobaltato of Lanthanum and Ferrato of Cobalt and Lanthanum, which were submitted to the combustion process assisted by microwave power maximum of 10min. The samples were characterized by: thermogravimetric analysis, X-ray diffraction; fisisorção of N2 (BET method) and scanning electron microscopy. The reactions catalytic of depolymerization of poly (methyl methacrylate), were performed in a reactor of silica, with catalytic and heating system equipped with a data acquisition system and the gas chromatograph. For the catalysts synthesized using the polymeric precursor method, the cuprate of lanthanum was best for the depolymerization of the recycled polymer, obtaining 100% conversion in less time 554 (min), and the pure polymer, was the Niquelate of Lanthanum, with 100% conversion in less time 314 (min). By gel-combustion method using urea as fuel which was the best result obtained Ferrate of Lanthanum for the pure polymer with 100% conversion in less time 657 (min), and the recycled polymer was Cobaltate of Lanthanum with 100 % conversion in less time 779 (min). And using citric acid to obtain the best result for the pure polymer, was Ferrate of Lanthanum with 100% conversion in less time 821 (min and) for the recycled polymer, was Ferrate of Lanthanum with 98.28% conversion in less time 635 (min)

Comportamento magnético de compósitos de matriz polimérica com adição de ferritas

Polymer matrix composites offer advantages for many applications due their combination of properties, which includes low density, high specific strength and modulus of elasticity and corrosion resistance. However, the application of non-destructive techniques using magnetic sensors for the evaluation these materials is not possible since the materials are non-magnetizable. Ferrites are materials with excellent magnetic properties, chemical stability and corrosion resistance. Due to these properties, these materials are promising for the development of polymer composites with magnetic properties. In this work, glass fiber / epoxy circular plates were produced with 10 wt% of cobalt or barium ferrite particles. The cobalt ferrite was synthesized by the Pechini method. The commercial barium ferrite was subjected to a milling process to study the effect of particle size on the magnetic properties of the material. The characterization of the ferrites was carried out by x-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM) and vibrating sample magnetometry (VSM). Circular notches of 1, 5 and 10 mm diameter were introduced in the composite plates using a drill bit for the non-destructive evaluation by the technique of magnetic flux leakage (MFL). The results indicated that the magnetic signals measured in plates with barium ferrite without milling and cobalt ferrite showed good correlation with the presence of notches. The milling process for 12 h and 20 h did not contribute to improve the identification of smaller size notches (1 mm). However, the smaller particle size produced smoother magnetic curves, with fewer discontinuities and improved signal-to-noise ratio. In summary, the results suggest that the proposed approach has great potential for the detection of damage in polymer composites structures

Aplicação da metodologia de planejamento de experimentos para formulação de massas cerâmicas para telhas

Rio Grande do Norte State stands out as one great producer of structural clay of the brazilian northeastern. The Valley Assu ceramic tiles production stands out obtained from ilitics ball clays that abound in the region under study. Ceramics formulation and the design of experiments with mixture approach, has been applied for researchers, come as an important aid to decrease the number of experiments necessary to the optimization. In this context, the objective of this work is to evaluate the effects of the formulation, temperature and heating rate in the physical-mechanical properties of the red ceramic body used for roofing tile fabrication of the Valley Assu, using design of mixture experiments. Four clays samples used in two ceramics industry of the region were use as raw material and characterized by X-ray diffraction, chemical composition, differential thermal analysis (DTA), thermogravimetric analysis (TGA), particle size distribution analysis and plasticity techniques. Afterwards, they were defined initial molded bodies and made specimens were then prepared by uniaxial pressing at 25 MPa before firing at 850, 950 and 1050 ºC in a laboratory furnace, with heating rate in the proportions of 5, 10 e 15 ºC/min. The following tecnologicals properties were evaluated: linear firing shrinkage, water absorption and flexural strength. Results show that the temperature 1050 ºC and heating rate of 5 ºC/min was the best condition, therefore presented significance in all physical-mechanical properties. The model was accepted as valid based of the production of three new formulations with fractions mass diferents of the initial molded bodies and heated with temperature at 1050 ºC and heating rate of 5 ºC/min. Considering the formulation, temperature and heating rate as variables of the equations, another model was suggested, where from the aplication of design of experiments with mixtures was possible to get a best formulation, whose experimental error is the minor in relation to the too much formulations

Comparação da análise de diferentes perfis de poços pelo método DFA

The study of complex systems has become a prestigious area of science, although relatively young . Its importance was demonstrated by the diversity of applications that several studies have already provided to various fields such as biology , economics and Climatology . In physics , the approach of complex systems is creating paradigms that influence markedly the new methods , bringing to Statistical Physics problems macroscopic level no longer restricted to classical studies such as those of thermodynamics . The present work aims to make a comparison and verification of statistical data on clusters of profiles Sonic ( DT ) , Gamma Ray ( GR ) , induction ( ILD ) , neutron ( NPHI ) and density ( RHOB ) to be physical measured quantities during exploratory drilling of fundamental importance to locate , identify and characterize oil reservoirs . Software were used : Statistica , Matlab R2006a , Origin 6.1 and Fortran for comparison and verification of the data profiles of oil wells ceded the field Namorado School by ANP ( National Petroleum Agency ) . It was possible to demonstrate the importance of the DFA method and that it proved quite satisfactory in that work, coming to the conclusion that the data H ( Hurst exponent ) produce spatial data with greater congestion . Therefore , we find that it is possible to find spatial pattern using the Hurst coefficient . The profiles of 56 wells have confirmed the existence of spatial patterns of Hurst exponents , ie parameter B. The profile does not directly assessed catalogs verification of geological lithology , but reveals a non-random spatial distribution