Estudo da sinterização do aço inox 316L reforçado com 3% Carbeto de Tântalo - TaC

The present work shows a contribution to the studies of development and solid sinterization of a metallic matrix composite MMC that has as starter materials 316L stainless steel atomized with water, and two different Tantalum Carbide TaC powders, with averages crystallite sizes of 13.78 nm and 40.66 nm. Aiming the metallic matrix s density and hardness increase was added different nanometric sizes of TaC by dispersion. The 316L stainless steel is an alloy largely used because it s high resistance to corrosion property. Although, its application is limited by the low wear resistance, consequence of its low hardness. Besides this, it shows low sinterability and it cannot be hardened by thermal treatments traditional methods because of the austenitic structure, face centered cubic, stabilized mainly in nickel presence. Steel samples added with TaC 3% wt (each sample with different type of carbide), following a mechanical milling route using conventional mill for 24 hours. Each one of the resulted samples, as well as the pure steel sample, were compacted at 700 MPa, room temperature, without any addictive, uniaxial tension, using a 5 mm diameter cylindrical mold, and quantity calculated to obtain compacted final average height of 5 mm. Subsequently, were sintered in vacuum atmosphere, temperature of 1290ºC, heating rate of 20ºC/min, using different soaking times of 30 and 60 min and cooled at room temperature. The sintered samples were submitted to density and micro-hardness analysis. The TaC reforced samples showed higher density values and an expressive hardness increase. The complementary analysis in optical microscope, scanning electronic microscope and X ray diffractometer, showed that the TaC, processed form, contributed with the hardness increase, by densification, itself hardness and grains growth control at the metallic matrix, segregating itself to the grain boarders

Alguns aspectos sobre o processo da democratização dos sistemas políticos no mundo árabe :Egito e Líbano como modelos de estudo

The World has tried diverse democratic waves at distinct moments. Some nations have adopted the idea of the democracy for years; others have not yet and other ones are still in a slow process of transition. The field of studies on the Arabian political systems has testified since the last quarter of 20th century a notorious development. This advance disclosed in the existence of a set of trends that has turned around a number of concepts and main theoretical frames such as the political pluralism and the democratic transition and the civil society and its relation with the State. The speech on the process of democratic transition consists in part in the capture and the analysis of the role of the forces and the organizations of the civil society in this process. The peculiarities of the Arab World excite questions concerning the establishment of one governmental system in this universe in the mold of that one that develops with hegemony in the Occident, which has become an interesting field of inquiries for the Political Science. This study comprises the analysis of some aspects of the political situation in the Arab World towards the process of democratization in which Egypt and Lebanon are models of study. Thus the theoretical basis of the term democracy is introduced, presenting different considerations about this expression, since the sprouting of the term until its current conception; later the civil society is analyzed as well as the systems of the political parties and the electoral systems of both countries in attempt to identify the level of democratization existing there and also to find the possible ways to magnify the democratic horizons

Argamassas do grupo escolar Augusto Severo/RN: caracterização e incidência de manifestações patológicas

The search for cultural heritage preservation should be a constant, in order to minimize the lost of historical and cultural identity of a country. As part of this cultural heritage, highlights the importance of historical buildings. For the principles of restoration are met its important to know the state of conservation and the existing materials. Given the above, this work aims to study the pathological manifestations of the mortar coating from the Grupo Escolar Augusto Severo. For this, was conducted historical survey of the building, on-site visits with visual observation, collecting samples of mortar coating and characterization through visual and laboratory analysis, XRF, XRD, TG/DTG, OM and SEM-EDS. From the observations, pathological manifestations were found as: cracks, detachment of the coating, dirt, use of inappropriate material basis of cement, efflorescence, mold and mildew and also incompatible material base of cement. It was found that the pathological manifestations were intensified due to lack of coverage in some spots and especially the abandonment of the building, that many years does not have restoration or any other type of preventive and corrective maintenance. The results of laboratory tests indicated that the mortars studied are based on lime, with calcitic nature, and siliceous aggregate, with the presence of clay in two samples. From the samples collected, two are composed of lime, sand and clay and two by lime and sand. In this regard, it is important to conduct periodic inspections and maintenance, as well as carrying out restoration with use of material compatible with the original

Construção e análise de desempenho de um fogão solar à concentração utilizando dois focos para cozimento direto

A model of a solar oven with a reflective surface composed of two mirror segments is presented, constituting a two semi-parabolic surfaces made of fiberglass, applied on a ceramic mold, intended to be used in residential and commercial cooking. The reflective surface of the semi-parable is obtained with the use of multiple plain segments of 2 mm wide mirrors. The semi-parabolic structure has visible movements that are comparable to that of the sun. The technical details of the manufacturing and assembling processes will be presented with an analysis of the viability of thermal, economic, and materials of such prototype. This prototype has important social implications and primordial aspects, which combats the ecological damages caused by the wide-scale use of firewood during cooking. It has been demonstrated that the solar oven has the capacity to cook simultaneous two meals distinct for a family of four

Desenvolvimento de um compósito de espuma rígida de poliuretana de mamona e fibras de sisal para isolação térmica

The search for sustainable technologies that can contribute to reduce energy consumption is a great challenge in the field of insulation materials. In this context, composites manufactured from vegetal sources are an alternative technology. The principal objectives of this work are the development and characterization of a composite composed by the rigid polyurethane foam derived from castor oil (commercially available as RESPAN D40) and sisal fibers. The manufacture of the composite was done with expansion controlled inside a closed mold. The sisal fibers where used in the form of needlepunched nonwoven with a mean density of 1150 g/m2 and 1350 g/m2. The composite characterization was performed through the following tests: thermal conductivity, thermal behavior, thermo gravimetric analysis (TG/DTG), mechanical strength in compression and flexural, apparent density, water absorption in percentile, and the samples morphology was analyzed in a MEV. The density and humidity percentage of the sisal fiber were also determined. The thermal conductivity of the composites was higher than the pure polyurethane foam, the addition of nonwoven sisal fibers will become in a higher level of compact foam, reducing empty spaces (cells) of polyurethane, inducing an increase in k value. The apparent density of the composites was higher than pure polyurethane foam. In the results of water absorption tests, was seen a higher absorption percent of the composites, what is related to the presence of sisal fibers which are hygroscopic. From TG/DTG results, with the addition of sisal fibers reduced the strength to thermal degradation of the composites, a higher loss of mass was observed in the temperature band between 200 and 340 °C, related to urethane bonds decomposition and cellulose degradation and its derivatives. About mechanical behavior in compression and flexural, composites presented a better mechanical behavior than the rigid polyurethane foam. An increase in the amount of sisal fibers induces a higher rigidity of the composites. At the thermal behavior tests, the composites were more mechanically and thermally resistant than some materials commonly used for thermal insulation, they present the same or better results. The density of nonwoven sisal fiber had influence over the insulation grade; this means that, an increaser in sisal fiber density helped to retain the heat

Avaliação do comportamento tribológico de compósitos poliéster/fibra de vidro utilizando resíduos de poliéster/fibra de vidro e carbonato de cálcio como carga

The use of composite materials and alternative is being increased every day, as it becomes more widespread awareness that the use of renewable and not harmful to the environment is part of a new environmentally friendly model. Since its waste (primarily fiberglass) can not be easily recycled by the difficulty that still exists in this process, since they have two phases mixed, a polymeric matrix thermoset difficult to recycle because it is infusible and phase of fiber reinforcements. Thermoset matrix composites like Polyester + fiberglass pose a threat due to excessive discharge. Aiming to minimize this problem, aimed to reuse the composite Polyester + fiber glass, through the wastes obtained by the grinding of knifes and balls. These residues were incorporated into the new composite Polyester/Fiberglass for hot compression mold and compared tribological to composites with filler CaCO3, generally used as filler, targeting a partial replacement of CaCO3 by such waste. The composites were characterized by thermal analysis (TGA, DSC and DMA), by the surface integrity (roughness determination, contact angle and surface energy), mechanical properties (hardness) and tribological tests (wear and coefficient of dynamic friction) in order to evaluate the effect of loads and characterize these materials for applications that can take, in the tribological point of view since waste Polyester + fiberglass has great potential for replacement of CaCO3

Análise térmica e mecânica de um compósito de matriz cerâmica com carga de EPS e raspa de pneu para construção de casas populares

Space Science was built using a composite made of plaster, EPS, shredded tires, cement and water. Studies were conducted to thermal and mechanical resistance. Inside the mold EPS plates were placed in order to obtain a higher thermal resistance on the wall constructed, as well as to give it an end environmentally friendly in view of both the tire and the EPS occupy a large space in landfills and year need to be degraded when released into the environment. Compression tests were performed according to ABNT blocks to seal, measurements of the temperature variation in the external and internal walls using a laser thermometer and check the temperature of the indoor environment using a thermocouple attached to a digital thermometer. The experiments demonstrated the heat provided by the composite values from the temperature difference between the internal and external surfaces on the walls, reaching levels of 12.4 ° C and room temperature in the interior space of the Science of 33.3 ° C, remaining within the zone thermal comfort for hot climate countries. It was also demonstrated the proper mechanical strength of such a composite for sealing walls. The proposed use of the composite can contribute to reducing the extreme housing shortage in our country, producing popular homes at low cost and with little time to work

Morfologia e propriedades mecânicas da fibra de sisal unidirecional e em sobreposição de compósito com resina epóxi

The composites manufactured with long fibres aligned in a single direction, and overlay has been shown to have better performance than the short fibers randomly distributed. In particular, the lignocellulosic fibers extracted from the sisal leaves, used in conjunction with the epoxy resin has attracted the attention of many researchers because the final properties of the system formed. In this work composites based on epoxy resin reinforced with sisal fibers were manufactured. The sisal fibres were treated with an alkaline solution of 0.06 mol/l NaOH. The treated, and untreated fibres were subjected to tension x extension tests. The composites were manufactured in the "Lossy" mold with the specifications of the samples to be produced (300x20x4 mm). The tension tests were carried out in accordance with the ASTM standards 3039 (for the composite aligned in a single direction) and ASTM D5573 (for composites in overlay), three point bending tests were performed according to ASTM D790. Analyzing the results of the tests of tension and three point bending tests, it was observed that the composites with the configuration of overlapping had the better elastic module in both tests. As to the maximum resistance to tension, the best result was the composites aligned in a single direction. Tests of absorption of water and micrographs are in progress

Estudo do aproveitamento do rejeito da mineração de esmeraldas na produção de refratários conformados isolantes

Emerald mining is an important area of the economy in Brazil, country which is in second place among the exporting nations of this gem. Due to the process of extraction, a great amount of reject is generated. Since there is no appropriate destination, the reject is abandoned around the mining industries, contributing to environment degradation. Nowadays, some of the most relevant things to an industry in general are: energy conservation, cost reduction, quality and productivity enhancement. The production of isolating, transformed refractory materials achieves the sustainability dimension when protection of the environment is incorporated to such process. This work investigates the use of emerald mining rejects in the ceramic body of refractory materials, aiming at obtaining a product whose characteristics are compatible with commercial products and, at the same time, allow the use of such rejects to solve the environmental issue caused by its disposal in nature. X-ray fluorescence analysis show that the emerald reject obtained after the flotation to extract molybdenum and mica has 70% of silica and alumina (SiO2+Al2O3) and 21% of a basic oxides and alkaline metals and earthy alkaline mixture (Na2O, K2O, CaO e MgO). Because of the significant amount of silica and alumina present in the reject, four refractory ceramic bodies were prepared. Samples with a rectangular shape and dimensions 100x50x10 mm were pressed in a steel mold at 27,5 MPa and sintered at 1200ºC for 40 min. under environment atmosphere in a resistive oven. The sintered samples were characterized in relation to the chemical composition (FRX), mineralogical composition (DRX), microstructure (MEV) and physical and mechanical properties. The results indicate that the mixture with 45% of reject, 45% of alumina and 10% of kaolin presents a refractory quality of 1420ºC, dimensional linear variation below 2.00%, apparent specific mass of 1,56 g/cm3 and porosity of 46,68%, which demonstrates the potential use of the reject as raw material for the industry of isolating transformed refractory materials

Viabilidade de uso de um fogão solar para cocção de alimentos com parábola refletora fabricada em compósito que utiliza fibras de Carnaúba e resina Ortoftálica

Presents a composite formed by orthophthalic resin and fiber loading of carnauba straw. The fibers were first dried in direct sun exposure and subsequently ground into fodder for the reduction in size. Various formulations of the composite were preliminarily tested by choosing the one presenting the best processability in applying the mold. The composite produced is used for the manufacture of a parabolic surface subsequently coated with mirror segments, flexible plastic, for reflecting the solar rays incident on it. The reflective parable represents the main element of the solar cooker that works with the concentration of sunlight and has dimensions of 1.14 m in diameter and area of 1.0 m². Manufacturing processes and assembly of solar cooker concentration produced are presented. The results of tests for cooking and baking various foods, including rice, pasta, beans, cake, cassava, shrimp, beef, breaded demonstrating the competitiveness of solar cooker studied with other stoves already manufactured and tested in Brazil are presented and in the world. It was also demonstrated the feasibility of the proposed composite for Prototypes manufacture of solar and other structures that do not require great efforts resistance

Ideologia e poder no agendamento do discurso polifônico da imprensa em relação à seca no nordeste

This dissertation work is an effort to understand how the ideology and the power interferes in the signification of the speeches immersed in the context of the printed media concerning the drought in the Northeast of Brazil, weather occurrence that punishes 23 million of Brazilians, with all sort of problems. It also has specific concern about the everyday usage of the language and with the routines of the information production, without losing of sight the role of History in the formation of the identity of individuals and people. The research work is also developed in an interdisciplinary environment, applying to the formed corpus five articles from Folha de São Paulo , collected from January to July of 2005, the French Analysis method of the Speech and the theory of the polyphony of Bakhtin, in the Applied Linguistics area, accomplished with Communication beddings as the agenda-setting. The results ended to a good understanding about the ideology and power´s influence and chaining in the speeches formations as well as to comprehend peoples concept in an environment of almost-mediated interaction, bringing a media look about polyphony in the bakhtinian mold, besides showing how all these questions interferes with the half-barren the Northeast media´s vision on the subject

O conceito de consciência em o ser e o nada de J.-P. Sartre

This current discourse intends to prove how consciousness or Being-for-itself presents the idea that in its operation one can emphasize that it s Nothingness, transience and liberty in Jean-Paul Sartre s work O Ser e o Nada. To testify the proposed idea, the conception that Sartre gives to consciousness, representing nothingness, without any content that is connected to the possessor objects of a transphenomenal existence will be the starting point. This way, consciousness will be analyzed transcendently to the object that it s not, demonstrating its revealer-revealed condition, because it unveils a concrete world that exists against its idea, functioning as the revealer intentionality that there are beings instead of nothingness, obeying the ontological proof defended by Sartre. From this idea, every kind of consciousness will always be consciousness of something, a glance of the world, avoiding the fact that the consciousness could be considered nothing in the world. In order to live its original negation state of the world, apprehending this same world, with the purpose of a knowledge, it needs to be divided in two: the first degree consciousness or previous-reflexive cogito, that turns the proper reflexion possible, because, it s the consciousness proper transphenomenality of being different of all that connected to its existence being only its consequence; and the cogito, responsible to the positioning of the first degree consciousness, while aware of its own consciousness, that is, while being certain that knows. From this point, the way to untangle the consciousness or Being-for-itself will be developed as being Chasm, Liberty and transience. From this idea, it s intended to know how consciousness, that in Sartre s thoughts is originally nothing, could turn into Liberty that is presented in the field of transience? In other words, how these three internal structures imbricate one another to form consciousness in Sartre? First of all, it has to be considered the review of a conduct of human reality, the inquiry, that will be possible to understand how Nothingness exists as the mold of all kind of negation. After this, it will be shown, considering its way of existence, the human reality that is connected to Para-si, determined like nothingness, still is proposed like Liberty. Form this point, it will be possible to gleam how Liberty is lived deeply by Para-si in the shape of chasm, trying to how Para-si turns into nothingness, creating a chasm based on its proper liberty. Then, Liberty will be the proper mechanism used by Para-si to modificate its original chasm. The way Being-for-itself has to build to gain its goal will be projecting in transience, the building of something possible that brings one being back. However, will be demonstrated like Chasm can occupy the moment of a choice turning the decision instant an anguish stage, based on the failing of stability of the Being-for-itself, once nothingness persists in the field of the possibilities that human beings preserves in its essence while being essentially Liberty. From this idea, anguish will be studied as the proper consciousness of Liberty, being bad-faith the attempt of avoid Liberty trying to gain a shelter contradicting the fact that life is done of continual choices

Estrutura genética de populações de Amphobotrys ricini, agente causal do mofo cinzento da mamoneira

The gray mold, causal organism Amphobotrys ricini, is one of the major diseases of castor bean. Difficulties in managing plant disease arises form the limited understanding of the genetic structure of A. ricini, their complexity and variability make it difficult to control. Genetic structure can be used to infer the relative impact of different forces that influence the evolution of pathogen populations, that allow to predict the potencial for pathogen populations to envolve in agricultural ecosystems. Growers protect their crop by applying fungicides, but there aren t fungicides to provide significant control of gray mold of castor bean. The objectives of this work were use RAPD to determine the genetic structure of A. ricini subpopulations in Paraíba and assay the sensitivity of A. ricini isolates to azoxystrobin and carbendazim. To determine the genetic structure of A. ricini subpopulations in Paraíba, 23 isolates were colleted from two different geographic location (subpopulation). These isolates were analysed by RAPD using 22 random decamer primers, purchased from OPERON, produced a total of 80 markers polimorphics. The resulting matrixes were analysed using PopGene version 1.32. Sensitivity to azoxystrobin and carbendazim of 30 isolates, colleted form Paraíba and Alagoas, was estimated based on spore germination and colony growth inhibition. The stock solutions were added toV8 medium after sterilization to produce final concentrations of 0, 0.01, 0.1, 1, 10, and 100 µg/ml of carbendazim and 0, 0.001, 0.01, 0.1, 1, and 10 µg/ml of azoxystrobin. All statistical analyses were performed using SAS to estimate the dose that inhibited fungal growth by 50% (ED50 values). The genetic diversity within subpopulations (Hs=0,271) accounted for 92% of the total genetic diversity (Ht=0,293), while genetic diversity between subpopulations (Gst = 0,075) represented only 7,5%. The estimated number of migrants per generation (NM ) was 6,15. Nei s average gene identity across 80 RAPD loci was 0,9468. Individual ED50 values, for the 30 isolates screened for their sensitivity to azoxystrobin, ranged From a maximum of 0,168 µg/ml to a minimum of 0,0036 µg/ml. The ED50 values for carbendazim varied within the range of 0,026 to 0,316 µg/ml

A terapia comunitária e a vivência de estudantes de medicina: uma estratégia de ensino aprendizagem do cuidado humanizado na ESF?

Before the scenario full of criticism about a medical model that gives privilege to the diseases and not to the diseased, there are many arguments that defend the need of redeem the humanized relationship between doctor and patient. It became indispensable to mold during the medical graduation a professional capable of perform a special care, less instrumental and more humanized; however, even though the advances of the pedagogical program of the medical graduation, we still face numerous challenges in the process of molding. This study has as general goal to understand if the students medicine experience with the Integrative Community Therapy (TCI) at the Primary Attention – APS/Family Healthy Strategy-ESF, presents potential to configure itself while strategy of teaching-learning to the integral and humanized care. It was held a qualitative research with the students of the medical graduation from the tenth to the twelfth semester that had experience with the TCI, as part of the Boarding of Family and Community Medicine – MFC. We used interviews with script and we resorted to analyze the narratives to Gadamerian Hermeneutics. It was possible to find that before join the boarding of MFC, the students were unaware the TCI and their preconceptions lined up with depreciated character. The experience with the TCI enabled the reframing of the prejudices and the build of new concepts. Internship in ESF and participate of TCI revealed potential to learning of the humanized care by the practical exercise with experiences that privilege the built of ties; the autonomy of the patient; the fulfillment of the longitudinality at the care of the patient; the acknowledgment of the power of resilience of the patients, at the strength of the collective, at the pain sharing, at the strength of a good communication, at the gains of qualified listening exercise. The absence of models of what to do was replaced by experiences of pains and joys at the learning of becoming a doctor. The pains spoke of the structural difficulties (inputs), at the get along with the socials vulnerabilities of the users and the difficult of perform a good communication with the patients. The joys were experienced at the finding of the humanized care exercise. Questions as structural difficulties, low number of people with TCI degree, a shortly experience of with TCI, show up as limitations to its utilization as pedagogical tool. In turn, the reflective potential is capable of cause resignifications about the know-how before the pain of the other being very much present at the narratives, signaling the potential of the learning of TCI. Therefore, this study advocate that the participation of the students at the TCI, beyond the power of offering the students a teaching-learning strategy to the humanized care, represents the possibility of enlarge the horizons of those future doctors at a glance much more conscious of the difficulties and potential of a professional at the ESF, contributing to the graduation of more sensitized professionals and prepared to perform an integral and humanized approach of the person and his/her community, contributing to an APS/ESF more resolute and rewarding to everyone.

Influência do retardante de chamas nas propriedades mecânicas e flamabilidade em compósitos poliméricos de epóxi/fibra de curauá

Currently, there is a great search for materials derived from renewable sources. The vegetable fibers as reinforcement for polymer matrixes, has been used as an alternative to replace synthetic fibres, being biodegradable and of low cost. The present work aims to develop a composite material with epoxy resin reinforced with curauá fibre with the addition of alumina trihydrate (aluminum hydroxide, Al(OH)3) as a flame retardant, which was used in proportions of 10 %, 20% and 30% of the total volume of the composite. The curauá fibers have gone through a cleaning process with an alkaline bath of sodium hydroxide (NaOH ), parallelized by hand and cut carding according to the default length . They were molded composites with fibers 30cm. Composites were molded in a Lossy Mold with unidirectional fibres in the proportion of 20% of the total volume of the composite. The composites were prepared in the Chemical Processing Laboratory of the Textile Engineering Department at UFRN. To measure the performance of the material, tests for the resistance to traction and flexion were carried out. with samples that were later analyzed in the Electronic Microscopy Apparatus (SEM ). The composites showed good mechanical properties by the addition of flame retardant and in some cases, leaving the composite more vulnerable to breakage. These mechanical results were analyzed by chi-square statistical test at the 5% significance level to check for possible differences between the composite groups. Flammability testing was conducted based on the standard Underwriters Laboratory 94 and the material showed a satisfactory result taking their average burn rate (mm / min) decreasing with increasing addition of the flame retardant composite.