Plasticidade dependente da experiência induzida por manipulação da matriz extracelular

The primary somatosensory cortex (S1) receives inputs from peripheral tactile receptors and plays a crucial role on many important behaviors. However, the plastic potential of this region is greatly reduced during adulthood, limiting functional recovery after injuries. This fact is due to the presence, in the brain parenchima, of structures and substances that have an inhibitory effect on plasticity, such as chondroitin sulfate proteoglicans (CSP) present in the perineuronal.nets (PNNs) surrounding a subset of neurons. Maturation of PNNs coincide with the closure of critical periods of plasticity in cortical areas, since CSP act to stabilize synaptic contacts. Removal of CSP is proven to be an effective therapeutic approach to restore plasticity and increase the odds of functional recovery after cortical lesion. In the present work, we removed CSP from the sensorimotor cortex of rats to restore plasticity and promote the compensatory morphofunctional regeneration of cortical circuits modified by removal of mystacial vibrissae during the critical period. Treatment with the CSP-digesting enzyme chondroitinase ABC proved efficient to restore plasticity in S1 circuits, as evidenced by morphological rearrangements and functional recovery.

Plasticidade dependente da experiência induzida por manipulação da matriz extracelular

The primary somatosensory cortex (S1) receives inputs from peripheral tactile receptors and plays a crucial role on many important behaviors. However, the plastic potential of this region is greatly reduced during adulthood, limiting functional recovery after injuries. This fact is due to the presence, in the brain parenchima, of structures and substances that have an inhibitory effect on plasticity, such as chondroitin sulfate proteoglicans (CSP) present in the perineuronal.nets (PNNs) surrounding a subset of neurons. Maturation of PNNs coincide with the closure of critical periods of plasticity in cortical areas, since CSP act to stabilize synaptic contacts. Removal of CSP is proven to be an effective therapeutic approach to restore plasticity and increase the odds of functional recovery after cortical lesion. In the present work, we removed CSP from the sensorimotor cortex of rats to restore plasticity and promote the compensatory morphofunctional regeneration of cortical circuits modified by removal of mystacial vibrissae during the critical period. Treatment with the CSP-digesting enzyme chondroitinase ABC proved efficient to restore plasticity in S1 circuits, as evidenced by morphological rearrangements and functional recovery.

Implementação de uma matriz de neurônios dinamicamente reconfigurável para descrição de topologias de redes neurais artificiais multilayer perceptrons

The Artificial Neural Networks (ANN), which is one of the branches of Artificial Intelligence (AI), are being employed as a solution to many complex problems existing in several areas. To solve these problems, it is essential that its implementation is done in hardware. Among the strategies to be adopted and met during the design phase and implementation of RNAs in hardware, connections between neurons are the ones that need more attention. Recently, are RNAs implemented both in application specific integrated circuits's (Application Specific Integrated Circuits - ASIC) and in integrated circuits configured by the user, like the Field Programmable Gate Array (FPGA), which have the ability to be partially rewritten, at runtime, forming thus a system Partially Reconfigurable (SPR), the use of which provides several advantages, such as flexibility in implementation and cost reduction. It has been noted a considerable increase in the use of FPGAs for implementing ANNs. Given the above, it is proposed to implement an array of reconfigurable neurons for topologies Description of artificial neural network multilayer perceptrons (MLPs) in FPGA, in order to encourage feedback and reuse of neural processors (perceptrons) used in the same area of the circuit. It is further proposed, a communication network capable of performing the reuse of artificial neurons. The architecture of the proposed system will configure various topologies MLPs networks through partial reconfiguration of the FPGA. To allow this flexibility RNAs settings, a set of digital components (datapath), and a controller were developed to execute instructions that define each topology for MLP neural network.

Implementação de uma matriz de neurônios dinamicamente reconfigurável para descrição de topologias de redes neurais artificiais multilayer perceptrons

The Artificial Neural Networks (ANN), which is one of the branches of Artificial Intelligence (AI), are being employed as a solution to many complex problems existing in several areas. To solve these problems, it is essential that its implementation is done in hardware. Among the strategies to be adopted and met during the design phase and implementation of RNAs in hardware, connections between neurons are the ones that need more attention. Recently, are RNAs implemented both in application specific integrated circuits's (Application Specific Integrated Circuits - ASIC) and in integrated circuits configured by the user, like the Field Programmable Gate Array (FPGA), which have the ability to be partially rewritten, at runtime, forming thus a system Partially Reconfigurable (SPR), the use of which provides several advantages, such as flexibility in implementation and cost reduction. It has been noted a considerable increase in the use of FPGAs for implementing ANNs. Given the above, it is proposed to implement an array of reconfigurable neurons for topologies Description of artificial neural network multilayer perceptrons (MLPs) in FPGA, in order to encourage feedback and reuse of neural processors (perceptrons) used in the same area of the circuit. It is further proposed, a communication network capable of performing the reuse of artificial neurons. The architecture of the proposed system will configure various topologies MLPs networks through partial reconfiguration of the FPGA. To allow this flexibility RNAs settings, a set of digital components (datapath), and a controller were developed to execute instructions that define each topology for MLP neural network.

Obtenção, caracterização e utilização de um compósito com matriz de resina poliéster e carga de fibras de sisal

The constant search for sustainable alternatives has earned great effort of researchers in research and obtaining new materials, encouraging the rise of eco-friendly productive development and providing simple and practical solutions to economic profitability. In this sense, the use of materials derived from natural renewable sources, vegetables, has great potential applicability to sustainable development. As alternative materials plant fibers can be applied to production of a range of composite materials easing the use of materials derived from non-renewable this thesis were sisal mats used for achieving a composite matrix having as one orthophthalic polyester resin. The webs were subjected to surface treatment in boiling water for 15 minutes. The webs of sisal fibers used were, respectively, 5%, 10% and 15% of the composite weight. The composite was obtained and characterized mechanically and thermally to the chosen formulations. several plates of the composite to obtain the body of evidence for the characterization tests complying with the relevant rules were made. The obtained composites showed strength tensile and bending lower than the array, so it can be used where are required low load requests. The most significant result of the composite studied given to the impact energy absorption, far superior to the matrix used. Other properties were highlighted in oil absorption, and density. It proved the feasibility of obtaining the composite for the three formulations studied C5, C10 and C15 being the most feasible to C10. To demonstrate the feasibility of using composite were made a wall clock, a bench, a chair and a shelf, low mechanical stress structures. It was concluded that the sisal rugs exercised the load function in the composite.

Obtenção, caracterização e utilização de um compósito com matriz de resina poliéster e carga de fibras de sisal

The constant search for sustainable alternatives has earned great effort of researchers in research and obtaining new materials, encouraging the rise of eco-friendly productive development and providing simple and practical solutions to economic profitability. In this sense, the use of materials derived from natural renewable sources, vegetables, has great potential applicability to sustainable development. As alternative materials plant fibers can be applied to production of a range of composite materials easing the use of materials derived from non-renewable this thesis were sisal mats used for achieving a composite matrix having as one orthophthalic polyester resin. The webs were subjected to surface treatment in boiling water for 15 minutes. The webs of sisal fibers used were, respectively, 5%, 10% and 15% of the composite weight. The composite was obtained and characterized mechanically and thermally to the chosen formulations. several plates of the composite to obtain the body of evidence for the characterization tests complying with the relevant rules were made. The obtained composites showed strength tensile and bending lower than the array, so it can be used where are required low load requests. The most significant result of the composite studied given to the impact energy absorption, far superior to the matrix used. Other properties were highlighted in oil absorption, and density. It proved the feasibility of obtaining the composite for the three formulations studied C5, C10 and C15 being the most feasible to C10. To demonstrate the feasibility of using composite were made a wall clock, a bench, a chair and a shelf, low mechanical stress structures. It was concluded that the sisal rugs exercised the load function in the composite.

Aproveitamento da fibra do epicarpo do coco babaçu em compósito com matriz epóxi: estudo do efeito do tratamento da fibra

Nowadays the environmental issues are increasingly highlighted since the future of humanity is dependent on the actions taken by man. Major efforts are being expended in pursuit of knowledge and alternatives to promote sustainable development without compromising the environment. In recent years there has been a marked growth in the development of reinforced composite fiber plants, as an alternative for economic and ecological effects, especially in the substitution of synthetic materials such as reinforcement material in composites. In this current study the chemical- physical or (thermophysics )characteristics of the babassu coconut fiber, derived from the epicarp of the fruit (Orbignyda Phalerata), which the main constituents of the fiber: Klason lignin, insoluble, cellulose, holocellulose, hemicellulose and the content of ash and moisture will be determined. A study was conducted about the superficial modification of the fibers of the epicarp babassu coconut under the influence of chemical treatment by alkalinization, in an aqueous solution of NaOH to 2.5% (m/v) and to 5.0% to improve the compatibility matrix / reinforcement composite with epoxy matrix. The results of the changes occurred in staple fibers through the use of the techniques of thermogravimetric analyses (TG) and differential scanning calorimetry (DSC). The results found on thermal analysis on samples of fiber without chemical treatment (alkalinities), and on fiber samples treated by alkalinization show that the proposed chemical treatment increases the thermal stability of the fibers and provides a growth of the surface of area fibers, parameters that enhance adhesion fiber / composite. The findings were evaluated and compared with published results from other vegetable fibers, showing that the use of babassu coconut fibers has technical and economic potential for its use as reinforcement in composites

Adição de nanopartículas de Ti em matriz de Fe através da deposição por magnetron sputtering

Microalloyed steels constitute a specific class of steel with low amount of carbon and microalloying elements such as Vanadium (V), Niobium (Nb) and Titanium (Ti). The development and application of microalloyed steels and steels in general are limited to the handling of powders with particles of submicron or nanometer dimensions. Therefore, this work presents an alternative in order to construction of microalloyed steels utilizing the deposition by magnetron sputtering technique as a microalloying element addiction in which Ti nanoparticles are dispersed in an iron matrix. The advantage of that technique in relation to the conventional metallurgical processes is the possibility of uniformly disperse the microalloying elements in the iron matrix. It was carried out deposition of Ti onto Fe powder in high CH4, H2, Ar plasma atmosphere, with two deposition times. After the deposition, the iron powder with nanoparticles of Ti dispersed distributed, were compacted and sintered at 1120 ° C in resistive furnace. Characterization techniques utilized in the samples of powder before and after deposition of Ti were Granulometry, Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (DRX). In the case of sintered samples, it was carried out characterization by SEM and Vickers Microhardness assays. The results show which the deposition technique by magnetron sputtering is practicable in the dispersion of particles in iron matrix. The EDX microanalysis detected higher percentages of Ti when the deposition were carried out with the inert gas and when the deposition process was carried out with reactive gas. The presence of titanium in iron matrix was also evidenced by the results of X-ray diffraction peaks that showed shifts in the network matrix. Given these results it can be said that the technique of magnetron sputtering deposition is feasible in the dispersion of nanoparticles of iron matrix in Ti.

Estudo morfológico da blenda polimérica poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PET)

Among the options for plastics modification more convenient, both from a technical-scientific and economic, is the development of polymer blends by processing in the molten state. This work was divide into two stages, with the aim to study the phase morphology of binary blend PMMA / PET blend and this compatibilized by the addition of the poly(methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) copolymer (MMA-GMA-EA). In the first stage is analyzed the morphology of the blend at a preliminary stage where we used the bottle-grade PET in a Haake torque rheometer and the effect of compatibilizer in this blend was evaluated. In the second stage the blend was processed using the recycled PET in a single screw extruder and subsequently injection molding in the shape of specimens for mechanical tests. In both stages we used a transmission electron microscopy (TEM) to observe the morphologies of the samples and an image analyzer to characterize them. In the second stage, as well as analysis by TEM, tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM) was performed to correlate the morphology with the mechanical properties. The samples used in morphological analyzes were sliced by cryo-ultramicrotomy technique for the analysis by TEM and the analysis by SEM and AFM, we used the flat face of the block after cut cryogenic. It was found that the size of the dispersed phase decreased with the addition of MMA-GMA-EA in blends prepared in a Haake. In the tensile test, the values of maximum tensile strength and modulus of elasticity is maintained in a range between the value of pure PMMA the pure PET, while the elongation at break was influenced by the composition by weight of the PMMA mixture. The coupling agent corroborated the results presented in the blend PMMA / PETrec / MMA-GMA-EA (80/15/5 %w/w), obtained by TEM, AFM and SEM. It was concluded that the techniques used had a good morphologic correlation, and can be confirmed for final analysis of the morphological characteristics of the blends PMMA / PET

Formulação de pastas cimentícias com adição de suspensões de quitosana para cimentação de poços de petróleo

Primary cementing is one of the main operations in well drilling responsible for the mechanical stability and zonal isolation during the production of oil. However, the cement sheath is constantly under mechanical stresses and temperature variations caused by the recovery of heavy oil. In order to minimize fracture and wear of the cement sheath, new admixtures are developed to improve the properties of Portland cement slurries and avoid environmental contamination caused by leaking gas and oil. Polymers with the ability to form polymeric films are candidates to improve the properties of hardened cement slurries, especially their fracture energy. The present study aimed at evaluating the effect of the addition of a chitosan suspension on cement slurries in order to improve the properties of the cement and increase its performance on heavy oil recovery. Chitosan was dissolved in acetic ac id (0.25 M and 2 M) and added to the formulation of the slurries in different concentrations. SEM analyses confirmed the formation of polymeric films in the cementitious matrix. Strength tests showed higher fracture energy compared to slurries without the addition of chitosan. The formation of the polymeric films also reduced the permeability of the slurry. Therefore, chitosan suspensions can be potentially used as cementing admixtures for heavy oil well applications

Adição de resíduo cerâmico em pastas geopoliméricas para cimentação de poços de petróleo

The development of activities the of oil and gas sector have promoted the search for suitable materials for cementing oil wells. In the state of the Rio Grande do Norte, the integrity of the cement sheath tends to be impaired during steam injection, a procedure necessary to increase oil recovery in reservoirs with low-viscosity oil. The geopolymer is a material that can be used as alternative cement, since it has been used in the production of fire-resistant components, building structures, and for the control of toxic or radioactive residues. Geopolymers result from condensation polymer alkali aluminosilicates and silicates resulting three-dimensional polymeric structures. They are produced in a manner different from that of Portland cement, which is made an activating solution that is mixed with geopolymer precursor. Among the few works studied allowed us to conclude that the pastes prepared with metakaolin as precursor showed better performance of its properties. Several studies show the addition of waste clay as a means of reducing cost and improving end of the folder properties. On this basis, the goal is to study the influence of the addition of ceramic waste in geopolymer paste. To develop the study of rheology tests were carried out, filtered, thickening time, compressive strength, free water, specific gravity and permeability, according to the American Pretoleum Institute (API). The results for all formulations studied show that the folders have high mechanical strength to a light paste; low filtrate volume, absence of free water, very low permeability, slurry, consistent with a light paste, and thickening time low that can be corrected with the use of a retardant handle. For morphological characterization, microstructural, physical, chemical and thermal tests were carried out by XRD, MEV, DTA, TG, FTIR. In the trial of XRD, it was found that geopolymer is an amorphous material, with a peak of crystalline kaolinite. In tests of TG / DTA, revealed the presence of a significant event, which represents the mass loss related to water, and also observed the reduction of weight loss by increasing the concentration of ceramic waste. In the trial of MEV, we found a uniform matrix without the presence of other phases. In the trial of FT-IR, we observed the presence of the band related to water. From all results it was determined that the optimum concentration range of use is between 2.5 and 5% of waste ceramic

Comportamento da adição do carbeto de nióbio (nBC) na matriz metálica do aço ferrítico 15kH2mfa

The 15Kh2MFA steel is a kind of Cr-Mo-V family steels and can be used in turbines for energy generation, pressure vessels, nuclear reactors or applications where the range of temperature that the material works is between 250 to 450°C. To improve the properties of these steels increasing the service temperature and the thermal stability is add a second particle phase. These particles can be oxides, carbides, nitrites or even solid solution of some chemical elements. On this way, this work aim to study the effect of addition of 3wt% of niobium carbide in the metallic matrix of 15Kh2MFA steel. Powder metallurgy was the route employed to produce this metallic matrix composite. Two different milling conditions were performed. Condition 1: milling of pure 15Kh2MFA steel and condition 2: milling of 15Kh2MFA steel with addition of niobium carbide. A high energy milling was carried out during 5 hours. Then, these two powders were sintered in a vacuum furnace (10-4torr) at 1150 and 1250°C during 60 minutes. After sintering the samples were normalized at 950°C per 3 minutes followed by air cooling to obtain a desired microstructure. Results show that the addition of niobium carbide helps to mill faster the particles during the milling when compared with that steel without carbide. At the sintering, the niobium carbide helps to sinter increasing the density of the samples reaching a maximum density of 7.86g/cm³, better than the melted steel as received that was 7,81g/cm³. In spite this good densification, after normalizing, the niobium carbide don t contributed to increase the microhardness. The best microhardness obtained to the steel with niobium carbide was 156HV and to pure 15Kh2MFA steel was 212HV. It happened due when the niobium carbide is added to the steel a pearlitic structure was formed, and the steel without niobium carbide submitted to the same conditions reached a bainitic structure

Estudo da adição de resíduo de scheelita em matriz cerâmica: formulação, propriedades físicas e microestrutura

Extractivism mineral is considered an activity highly degrading, due to the large volume of material that he moves in the form of ore and residues. The vast majority of mining companies do not show any technology or economically viable application that will allow the recycling of mineral residue, these being launched in areas receiving located the "open skies" degrade the environment. In Rio Grande do Norte to the production of ceramic red restricts their activities to the production of products such as: solid bricks, ceramic blocks, tiles, among others. Seeking to unite experiences and technical information that favor sustainable development, with important benefits to the construction sector and civil society in general, the present work studies the incorporation of the residue of scheelite in ceramic matrix kaolinitic, coming from the municipality of Boa Saúde - RN, in percentage of 5 %, 10 %, 20 %, 30% 40% and 50 %, by evaluating its microstructure, physical properties and formulation. The raw materials were characterized through the trials of X ray fluorescence, Diffraction of X rays, Differential Thermal Analysis and Termogravimetric Analysis. The samples were formed and fired at temperatures of 850o, 900o, 1000o, 1050o, 1100o, 1150o and 1200 oC, with isotherm of 1 hour and heating rate of 10 oC/min. Assays were performed technological of loss to fire, Water Absorption, Apparent Porosity, Apparent Density, Mass Loss in Fire and Bending Resistance; in addition to the Scanning Electron Microscopy, analyzing their physical and mechanical properties. The use of residue of scheelite in ceramic mass kaolinitic provided a final product with technological properties that meet the technical standards for the production of bricks and roofing tiles, with the percentage of 20% of waste that showed the best results

Desenvolvimento e caracterização de um compósito matriz metálica (CMM): aço EUROFER97 reforçado com Carbeto de Tântalo - TaC

Steel is an alloy EUROFER promising for use in nuclear reactors, or in applications where the material is subjected to temperatures up to 550 ° C due to their lower creep resistance under. One way to increase this property, so that the steel work at higher temperatures it is necessary to prevent sliding of its grain boundaries. Factors that influence this slip contours are the morphology of the grains, the angle and speed of the grain boundaries. This speed can be decreased in the presence of a dispersed phase in the material, provided it is fine and homogeneously distributed. In this context, this paper presents the development of a new material metal matrix composite (MMC) which has as starting materials as stainless steel EUROFER 97, and two different kinds of tantalum carbide - TaC, one with average crystallite sizes 13.78 nm synthesized in UFRN and another with 40.66 nm supplied by Aldrich. In order to improve the mechanical properties of metal matrix was added by powder metallurgy, nano-sized particles of the two types of TaC. This paper discusses the effect of dispersion of carbides in the microstructure of sintered parts. Pure steel powders with the addition of 3% TaC UFRN and 3% TaC commercial respectively, were ground in grinding times following: a) 5 hours in the planetary mill for all post b) 8 hours of grinding in the mill Planetary only for steel TaC powders of commercial and c) 24 hours in the conventional ball mill mixing the pure steel milled for 5 hours in the planetary mill with 3% TaC commercial. Each of the resulting particulate samples were cold compacted under a uniaxial pressure of 600MPa, on a cylindrical matrix of 5 mm diameter. Subsequently, the compressed were sintered in a vacuum furnace at temperatures of 1150 to 1250 ° C with an increment of 20 ° C and 10 ° C per minute and maintained at these isotherms for 30, 60 and 120 minutes and cooled to room temperature. The distribution, size and dispersion of steel and composite particles were determined by x-ray diffraction, scanning electron microscopy followed by chemical analysis (EDS). The structures of the sintered bodies were observed by optical microscopy and scanning electron accompanied by EDS beyond the x-ray diffraction. Initial studies sintering the obtained steel EUROFER 97 a positive reply in relation to improvement of the mechanical properties independent of the processing, because it is obtained with sintered microhardness values close to and even greater than 100% of the value obtained for the HV 333.2 pure steel as received in the form of a bar

Efeito da adição de grafite expandido por microondas nas propriedades térmicas, elétricas e mecânicas de nanocompósitos de matriz epóxi

Epoxy based nanocomposites with 1 wt % and 3 wt % of nanographite were processed by high shear mixing. The nanographite was obtained by chemical (acid intercalation), thermal (microwave expansion) and mechanical (ultrasonic exfoliation) treatments. The mechanical, electrical and thermal behavior of the nanocomposites was determined and evaluated as a function of the percentage of reinforcement. According to the experimental results, the electrical conductivity of epoxy was not altered by the addition of nanographite in the contents evaluated. However, based on the mechanical tests, nanocomposites with addition of 1 wt.% and 3 wt.% of nanographite showed increase in tensile strength of 16,62 % and 3,20 %, respectively, compared to the neat polymer. The smaller increase in mechanical strength of the nanocomposite with 3 wt.% of nanographite was related to the formation of agglomerates. The addition of 1 wt.% and 3 wt.% of nanographite also resulted in a decrease of 6,25 % and 17,60 %, respectively, in the relative density of the material. Thus, the specific strength of the nanocomposites was approximately 33,33 % greater when compared to the neat polymer. The addition of 1 wt.% and 3 wt.% of nanographite in the material increased the mean values of thermal conductivity in 28,33 % and 132,62 %, respectively, combined with a reduction of 26,11 % and 49,80 % in volumetric thermal capacity, respectively. In summary, it has been determined that an addition of nanographite of the order of 1 wt.% and 3 wt.% produced notable elevations in specific strength and thermal conductivity of epoxy