Análise mecânica e microestrutural das ligas de cobalto-cromo de uso odontológico após sucessivas refundições

The cobalt-chromium alloy is extensively used in the Odontology for the confection of metallic scaffolding in partial removable denture. During the last few years, it has been reported an increasing number of premature imperfections, with a few months of prosthesis use. The manufacture of these components is made in prosthetic laboratories and normally involves recasting, using parts of casting alloy and parts of virgin alloy. Therefore, the objective of the present study was to analyze the mechanical properties of a commercial cobalt-chromium alloy of odontological use after successive recasting, searching information to guide the dental prosthesis laboratories in the correct manipulation of the cobalt-chromium alloy in the process of casting and the possible limits of recasting in the mechanical properties of this material. Seven sample groups were confectioned, each one containing five test bodies, divided in the following way: G1: casting only with virgin alloy; G2: casting with 50% of the alloy of the G1 + 50% of virgin alloy; G3: casting with 50% of the alloy of the G2 + 50% of virgin alloy; G4: casting with 50% of the alloy of the G3 + 50% of virgin alloy; G5: 50% of alloy of the G4 + 50% of virgin alloy; G6: 50% of alloy of the G5 + 50% of virgin alloy and finally the G7, only with recasting alloy. The modifications in the mechanical behavior of the alloy were evaluated. Moreover, it was carried the micro structural characterization of the material by optic and electronic scanning microscopy, and X ray diffraction.and fluorescence looking into the correlatation of the mechanical alterations with structural modifications of the material caused by successive recasting process. Generally the results showed alterations in the fracture energy of the alloy after successive recasting, resulting mainly of the increasing presence of pores and large voids, characteristic of the casting material. Thus, the interpretation of the results showed that the material did not reveal significant differences with respect to the tensile strength or elastic limit, as a function of successive recasting. The elastic modulus increased from the third recasting cycle on, indicating that the material can be recast only twice. The fracture energy of the material decreased, as the number of recasting cycles increased. With respect to the microhardness, the statistical analyses showedno significant differences. Electronic scanning microscopy revealed the presence of imperfections and defects, resulting of the recasting process. X ray diffraction and fluorescence did not show alterations in the composition of the alloy or the formation of crystalline phases between the analyzed groups. The optical micrographs showed an increasing number of voids and porosity as the material was recast. Therefore, the general conclusion of this study is that the successive recasting of of Co-Cr alloys affects the mechanical properties of the material, consequently leading to the failure of the prosthetic work. Based on the results, the best recommendadition is that the use of the material should be limited to two recasting cycles

Dinâmica espaço-temporal em uma guilda de borboletas frugívoras no limite norte da floresta atlântica nordestina

The extent of the Brazilian Atlantic rainforest, a global biodiversity hotspot, has been reduced to less than 7% of its original range. Yet, it contains one of the richest butterfly fauna in the world. Butterflies are commonly used as environmental indicators, mostly because of their strict association with host plants, microclimate and resource availability. This research describes diversity, composition and species richness of frugivorous butterflies in a forest fragment in the Brazilian Northeast. It compares communities in different physiognomies and seasons. The climate in the study area is classified as tropical rainy, with two well defined seasons. Butterfly captures were made with 60 Van Someren-Rydon traps, randomly located within six different habitat units (10 traps per unit) that varied from very open (e.g. coconut plantation) to forest interior. Sampling was made between January and December 2008, for five days each month. I captured 12090 individuals from 32 species. The most abundant species were Taygetis laches, Opsiphanes invirae and Hamadryas februa, which accounted for 70% of all captures. Similarity analysis identified two main groups, one of species associated with open or disturbed areas and a second by species associated with shaded areas. There was a strong seasonal component in species composition, with less species and lower abundance in the dry season and more species and higher abundance in the rainy season. K-means analysis indicates that choice of habitat units overestimated faunal perceptions, suggesting less distinct units. The species Taygetis virgilia, Hamadryas chloe, Callicore pygas e Morpho achilles were associated with less disturbed habitats, while Yphthimoides sp, Historis odius, H. acheronta, Hamadryas feronia e Siderone marthesia likey indicate open or disturbed habitats. This research brings important information for conservation of frugivorous butterflies, and will serve as baseline for future projects in environmental monitoring

A revenda de combustível e os limites constitucionais para a sua regulação: uma análise aplicada aos aspectos concorrênciais e ao controle de preços

The gas retail represents the end of a section of the oil and natural gas derivative chain, for it is at this stage where the commercialization of those merchandises takes place towards the costumers. This process involves an enormous amount of economic agents, which reflects on an activity of great influence on the citizen's everyday. By the time of the gas retail price liberalization, in 2002, there were great expectations towards that measure, for the insertion of that segment in a competitive market was likely to create a decrease in prices. As there was not a drastic drop off in cost, the question was no longer the price itself, but, predominantly, the conduct taken by the economic agents that operate the market. Not in vain, the segment introduces a greater number of different procedures combined with the organs that compose the Brazilian System of Competition Protection. What is understood, however, is that many of these complaints are made in a lightly way, without a proper analysis of the market and its practices, that being why, in this paper, evidences the causes of these complaints and explained what, in fact, occurs in this market. Also, the organs that protect the free initiative in the sector use different methods to assess anticompetitive practices, which are counterproductive on the combat of anticompetitive practice, that being why the present paper analyzes the used methods on a critic perspective, choosing one which is believed to be the most adequate. The present work also tries to present the gas retail prices on a constitutional, free competition, free initiative and consumers defense perspective, analyzing the competition s aspects on the gas market; the shaping of the gas prices; the market boundaries; the anti-competitive practices under the gas market; and analyze the possibility, according to the defined economic standards in the constitutional text of existing a greater control or gas price indexing and/or regulation which limits the distributors and resellers profit on gas. Still, in consequence of this analysis, a study on Natal s market behavior will be developed in its competitive feature. That being said, moreover being a theoretical-descriptive study, data and statistics gathered is used, which will lead, willing to grasp an experiential study on a few aspects of the Potiguar gas retail market

Tributação, finanças públicas e política fiscal: uma análise sob a óptica do direito e economia

In the Brazilian legal scenario, the study of taxation has traditionally been restricted to positivist analysis, concerned with investigating the formal aspects of the tax legal rule. Despite its relevance to the formation of the national doctrine of tax, such formalist tradition limits the discipline, separating it from reality and the socioeconomic context in which the Tax Law is inserted. Thus, the proposal of the dissertation is to examine the fundamentals and nature of taxation and tax legal rules from the perspective of Law and Economics (Economic Analysis of Law). For this purpose, the work initially reconnects the Tax Law and Science of Finance (or Public Finance) and Fiscal Policy, undertaking not only a legal analysis, but also economic and financial analysis of the theme. The Economics of Public Sector (or Modern Public Finance) will contribute to the research through topics such as market failures and economic theory of taxation, which are essential to an economic approach to Tax Law. The core of the work lies in the application of Law and Economics instruments in the study of taxation, analyzing the effects of tax rules on the economic system. Accordingly, the dissertation examines the fundamental assumptions that make up the Economic Analysis of Law (as the concept of economic efficiency and its relation to equity), relating them to the tax phenomenon. Due to the nature of the Brazilian legal system, any worth investigation or approach, including Law and Economics, could not pass off the Constitution. Thus, the constitutional rules will serve as a limit and a prerequisite for the application of Law and Economics on taxation, particularly the rules related to property rights, freedom, equality and legal certainty. The relationship between taxation and market failures receives prominent role, particularly due to its importance to the Law and Economics, as well as to the role that taxation plays in the correction of these failures. In addition to performing a review of taxation under the approach of Economic Analysis of Law, the research also investigates the reality of Brazilian tax system, applying the concepts developed in relevant cases and issues to the national scene, such as the relationship between taxation and development, the compliance costs of taxation, the tax evasion and the tax enforcement procedure. Given the above, it is intended to lay the groundwork for a general theory of Economic Analysis of Tax Law, contextualizing it with the Brazilian tax system

Metodologia de análise e diagnóstico de fratura em um componente automotivo sujeito a cargas cíclicas alternadas

The competitiveness of the trade generated by the higher availability of products with lower quality and cost promoted a new reality of industrial production with small clearances. Track deviations at the production are not discarded, uncertainties can statistically occur. The world consumer and the Brazilian one are supported by the consumer protection code, in lawsuits against the products poor quality. An automobile is composed of various systems and thousands of constituent parts, increasing the likelihood of failure. The dynamic and security systems are critical in relation to the consequences of possible failures. The investigation of the failure gives us the possibility of learning and contributing to various improvements. Our main purpose in this work is to develop a systematic, specific methodology by investigating the root cause of the flaw occurred on an axle end of the front suspension of an automobile, and to perform comparative data analyses between the fractured part and the project information. Our research was based on a flaw generated in an automotive suspension system involved in a mechanical judicial cause, resulting in property and personal damages. In the investigations concerning the analysis of mechanical flaws, knowledge on materials engineering plays a crucial role in the process, since it enables applying techniques for characterizing materials, relating the technical attributes required from a respective part with its structure of manufacturing material, thus providing a greater scientific contribution to the work. The specific methodology developed follows its own flowchart. In the early phase, the data in the records and information on the involved ones were collected. The following laboratory analyses were performed: macrography of the fracture, micrography with SEM (Scanning Electron Microscope) of the initial and final fracture, phase analysis with optical microscopy, Brinell hardness and Vickers microhardness analyses, quantitative and qualitative chemical analysis, by using X-ray fluorescence and optical spectroscopy for carbon analysis, qualitative study on the state of tension was done. Field data were also collected. In the analyses data of the values resulting from the fractured stock parts and the design values were compared. After the investigation, one concluded that: the developed methodology systematized the investigation and enabled crossing data, thus minimizing diagnostic error probability, the morphology of the fracture indicates failure by the fatigue mechanism in a geometrically propitious location, a tension hub, the part was subjected to low tensions by the sectional area of the final fracture, the manufacturing material of the fractured part has low ductility, the component fractured in an earlier moment than the one recommended by the manufacturer, the percentages of C, Si, Mn and Cr of the fractured part present values which differ from the design ones, the hardness value of the superior limit of the fractured part is higher than that of the design, and there is no manufacturing uniformity between stock and fractured part. The work will contribute to optimizing the guidance of the actions in a mechanical engineering judicial expertise

Análise da magnetohidrodinâmica com transferência de calor em canais de placas paralelas via transformação integral

The main goal of the present work is related to the dynamics of the steady state, incompressible, laminar flow with heat transfer, of an electrically conducting and Newtonian fluid inside a flat parallel-plate channel under the action of an external and uniform magnetic field. For solution of the governing equations, written in the parabolic boundary layer and stream-function formulation, it was employed the hybrid, numericalanalytical, approach known as Generalized Integral Transform Technique (GITT). The flow is sustained by a pressure gradient and the magnetic field is applied in the direction normal to the flow and is assumed that normal magnetic field is kept uniform, remaining larger than any other fields generated in other directions. In order to evaluate the influence of the applied magnetic field on both entrance regions, thermal and hydrodynamic, for this forced convection problem, as well as for validating purposes of the adopted solution methodology, two kinds of channel entry conditions for the velocity field were used: an uniform and an non-MHD parabolic profile. On the other hand, for the thermal problem only an uniform temperature profile at the channel inlet was employed as boundary condition. Along the channel wall, plates are maintained at constant temperature, either equal to or different from each other. Results for the velocity and temperature fields as well as for the main related potentials are produced and compared, for validation purposes, to results reported on literature as function of the main dimensionless governing parameters as Reynolds and Hartman numbers, for typical situations. Finally, in order to illustrate the consistency of the integral transform method, convergence analyses are also effectuated and presented

Análise topológica experimental por perfilometria cíclica indutiva de superficies de paredes estruturais

To enhance the maintenance practices, Oil and Gas Pipelines are inspected from the inside by automated systems called PIG (Pipeline Inspection Gauge). The inspection and mapping of defects, as dents and holes, in the internal wall of these pipelines are increasingly put into service toward an overall Structural Integrity Policy. The residual life of these structures must be determined such that minimize its probability of failure. For this reason, the investigation on the detection limits of some basic topological features constituted by peaks or valleys disposed along a smooth surface is of great value for determining the sensitivity of the measurements of defects from some combinations of circumferential, axial and radial extent. In this investigation, it was analyzed an inductive profilometric sensor to scan three races, radius r1, r2, r3, in a circular surface of low carbon steel, equipped with eight consecutive defects simulated by bulges and holes by orbit, equally spaced at p/4 rad. A test rig and a methodology for testing in laboratory were developed to evaluate the sensor response and identify their dead zones and jumps due to fluctuations as a function of topological features and scanning velocity, four speeds different. The results are presented, analyzed and suggestions are made toward a new conception of sensor topologies, more sensible to detect these type of damage morphologies

Uma análise crítica dos ideários pedagógicos contemporâneos à luz da teoria de A. N. Leontiev

O presente artigo objetiva demonstrar o alcance das pedagogias do aprender a aprender (DUARTE, 2001), uma vez que elas fundamentam as propostas educacionais no âmbito nacional e no internacional, na atualidade; bem como apresentar suas principais premissas, que mantêm sua filiação ao pragmatismo e ao irracionalismo e, no limite, submetem o desenvolvimento humano à ordem do capital. Tais proposições se contrapõem ao objetivo humanizador da educação escolar pressuposto na produção teórica do psicólogo soviético Alexis Leontiev. Como resultados, temos que, dessas produções, é possível extrair subsídios para o enfrentamento do processo de esvaziamento do ensino escolar e do papel do professor engendrado pelas referidas pedagogias. Além disso, pretendese evidenciar a impossibilidade de aproximações entre as produções da psicologia histórico-cultural com outras correntes pedagógicas que estão a serviço da legitimação e do revigoramento da sociedade capitalista.

Análise imunoistoquímica da distribuição de Serotonina, transportador de serotonina e receptores de serotonina no hipotálamo do sagui (callithrix jacchus)

The hypothalamus is a diencephalic portion located around the third ventricle below the hypothalamic sulcus, limited by the optic chiasm, and by the mammillary bodies, acting as a center that integrates behavioral and homeostatic functions. Serotonin is a neurotransmitter produced in limited sites in the midbrain and brain stem, but is distributed throughout the central nervous system and has many functions, acting through specific receptors that are also distributed throughout the nervous system. Using immunohistochemical techniques, the aim of this study was to delineate the hypothalamic nuclei of the marmoset (Callithrix jacchus) and study the distribution of serotonin transporter and serotonin receptors in the hypothalamus of this species. We used the Nissl method to determine the cytoarchitecture of the hypothalamic nuclei, and immunohistochemistry to reveal the presence of NeuN as a method to determine the contours of the hypothalamic nuclei. As a result, we found serotonin containing fibers and terminals throughout the rostrocaudal extent of the hypothalamus, more concentrated in some nuclei, and even absent in some. Like serotonin, serotonin transporter was observed between pre-optic area and tuberal region of the hypothalamus, in densities and distribution similar to serotonin. The 5-HT1A and 5-HT1B receptors were found with minor differences among itselves regarding the disposition and intensity of staining.

Validação de metodologia para análise de aminas bioativas em camarão utilizando cromatografia de íons

In this study, we worked with the validation of a methodology for analysis of bioactive amines in shrimp, considering it to be one of the main products of the northriograndense trade balance, maintaining the state of Rio Grande do Norte topped the list of Brazilian exports of this product the last decade. The sector of the Brazilian shrimp works exclusively with gray shrimp Litopenaeus Vannamei since the late 1990s. This study used liquid chromatography with conductimetric detector, using as the mobile phase methylsulfonic 3 mM acid (MSA) with gradient and phase C18 column with reverse the development of methodology for the analysis of bioactive amines in shrimp. In the sample preparation was used as 5% trichloroacetic acid (TCA) extraction solution. Validation analysis of biotativas amines (putrescine - PUT, histamine - HIST, agmatine - AGM, spermidine - EPD and spermine - EPN) in shrimp, the linear working range was 0.1 to 2.0 mg L-1 to was sensitive, homoscedastic, in effect, selective, accurate and precise array. Thus, considered feasible for these determinations bioactive amines in this array. Determined the concentration of these amines in fresh shrimps (AGM = 0.61 ± 0.05 mg kg- 1 EPD = 2.57 ± 0.14 mg kg-1 and EPN = 1.79 ± 0.11 mg kg-1), and freezing weather predetermined in cooked shrimp (AGM = 6.28 ± 0.18 mg kg-1, EPD = 12.72 ± 0.02 mg kg- 1 and EPN = 22.30 ± 0.60 mg kg-1), the shrimp with twenty-four hour stay at room temperature (PUT = 879.52 ± 28.12 mg kg-1, AGM = 848.13 ± 19.40 mg kg-1, ESPD = 13.59 ± 0.97 mg kg-1 and ESPN = 18.47 + 1.57 mg kg-1). In shrimp subjected to freezing for a week, two weeks, three weeks and four weeks, the results showed that there is an increase in the content of agmatine (7.31 ± 0.21 mg kg-1) while in spermine ( 1.22 ± 0.14 mg kg-1) and spermidine (below limit of quantification) there was a decrease in the freeze time, while there is a decrease in the level of spermidine not reaching detectad. The putrescine was only found in shrimp that remained for 24 hours at room temperature and histamine was not found in any of the samples

Efeitos da pressão limite (25 cmH2O) e mínima de "selo" do balonete de tubos traqueais sobre a mucosa traqueal do cão

JUSTIFICATIVA E OBJETIVOS: As lesões da mucosa traqueal em contato com o balonete do tubo traqueal são proporcionais à pressão exercida pelo balonete e ao tempo de exposição. O objetivo foi estudar as eventuais lesões da mucosa do segmento traqueal em contato com o balonete do tubo traqueal insuflado com volume de ar suficiente para se obter pressão de "selo" ou com a pressão limite de 25 cmH2O, abaixo da pressão crítica de 30 cm de água para produção de lesão da mucosa traqueal. MÉTODO: Dezesseis cães foram submetidos à anestesia venosa e ventilação artificial. Os cães foram distribuídos aleatoriamente em dois grupos de acordo com a pressão no balonete do tubo traqueal (Portex Blue-Line, Inglaterra): Gselo (n = 8) balonete com pressão mínima de "selo" para impedir vazamento de ar durante a respiração artificial; G25 (n = 8) balonete insuflado até obtenção da pressão de 25 cmH2O. A medida da pressão do balonete foi realizada por meio de manômetro digital no início (controle) e após 60, 120 e 180 minutos. Após o sacrifício dos cães, foram feitas biópsias nas áreas da mucosa traqueal adjacentes ao balonete e ao tubo traqueal para análise à microscopia eletrônica de varredura (MEV). RESULTADOS: A pressão média do balonete em G25 manteve-se entre 24,8 e 25 cmH2O e em Gselo entre 11,9 e 12,5 cmH2O durante o experimento. As alterações à MEV foram pequenas e não significantemente diferentes nos grupos (p > 0,30), mas ocorreram lesões mais intensas nas áreas de contato da mucosa traqueal com o balonete do tubo traqueal, nos dois grupos, em relação às áreas da mucosa adjacentes ou não ao tubo traqueal (p < 0,05). CONCLUSÕES: No cão, nas condições experimentais empregadas, a insuflação do balonete de tubo traqueal em volume de ar suficiente para determinar pressão limite de 25 cmH2O ou de "selo" para impedir vazamento de ar determina lesões mínimas da mucosa traqueal em contato com o balonete e sem diferença significante entre elas.

Análise comparativa das propriedades mecânicas do ligamento da patela e do tendão calcâneo

Com a finalidade de se comparar as propriedades mecânicas do ligamento da patela e do tendão calcâneo foram realizados ensaios de tração em material obtido de 25 cadáveres humanos. A idade dos doadores foi 58 ± 14 anos (33-85), sendo 19 (76%) masculinos e 6 (24%) femininos, 23 brancos (92%) e dois negros (8%). Os materiais foram testados em seus 10 mm centrais, com velocidade de aplicação de carga de 30 mm/min. Foi obtida a área de secção dos corpos de prova para que fossem estudadas as propriedades estruturais e materiais. Foram estudadas as seguintes variáveis: carga máxima (N), tensão(MPa), módulo de elasticidade (MPa), energia (Nm), alongamento absoluto (mm) e específico (%), limite de proporcionalidade (N), além da tensão (MPa) e alongamentos neste ponto. A análise estatística revelou que ambos possuem carga máxima, limite de proporcionalidade e tensão semelhantes (p>0,05). Nas outras variáveis ocorreu diferença significativa (p<0,05) com o tendão calcâneo apresentando valores maiores para energia e alongamento. O módulo de elasticidade, significativamente maior no ligamento da patela (p<0,05), foi a variável que melhor caracterizou a diferença do comportamento mecânico dos dois materiais.

Cartografia temporal e análise geoambiental da dinâmica da foz do Rio Piranhas-Açu, regiao de Macau-RN, com base em imagens Landast 5-MT

This work embraces the application of Landsat 5-TM digital images, comprising August 2 1989 and September 22 1998, for temporal mapping and geoenvironmental analysis of the dynamic of Piranhas-Açu river mouth, situated in the Macau (RN) region. After treatment using several digital processing techniques (e.g. colour composition in RGB, ratio of bands, principal component analysis, index methods, among others), it was possible to generate several image products and multitemporal maps of the coastal morphodynamics of the studied area. Using the image products it was possible the identification and characterization of the principal elements of interest (vegetation, soil, geology and water) in the surface of the studied area, associating the spectral characteristics of these elements to that presented by the image products resulting of the digital processing. Thus, it was possible to define different types of soils: Amd, AQd6, SK1 and LVe4; vegetation grouping: open arboreal-shrubby caatinga, closed arborealshrubby caatinga, closed arboreal caatinga, mangrove vegetation, dune vegetation and areas predominately constituted by juremas; geological units: quaternary units beach sediments, sand banks, dune flats, barrier island, mobile dunes, fixed dunes, alluvium, tidal and inundation flats, and sandy facies of the Potengi Formation; tertiary-quaternary units Barreiras Formation grouped to the clayey facies of the Potengi Formation, Macau Formation grouped to the sediments of the Tibau Formation; Cretaceous units Jandaíra Formation; moreover it was to identify the sea/land limit, shallow submersed areas and suspended sediments. The multitemporal maps of the coastal morphodynamics allowed the identification and a semi-quantitative evoluation of regions which were submitted to erosive and constructive processes in the last decade. This semi-quantitative evoluation in association with an geoenvironmental characterization of the studied area are important data to the elaboration of actions that may minimize the possible/probable impacts caused by the implantation of the Polo Gas/Sal and to the monitoring of areas explorated by the petroleum and salt industries

Faixas de proteção ambiental do Rio Pitimbu/RN: uma análise como subsídio ao planejamento e ordenamento do território

The Environmental Protection area sof Pitimbu river are important tools for planning and territorial land management. The Pitimbu river protection is aided in laws, so much of Federal stamp, as the Brazilian s Forest Code (Law No. 4771/1965), and in State s and City s Resolutions. So, this research begins in the State s Law No. 8426/2003interpretations, for being the most restrictive in the river's margin occupation and management. The objective is to analyze the applicability of the Environmental Protection areas of Pitimbu river, localized at the State of Rio Grande do Norte, considering environmental legislation and how to use this space by the man. Having specific goals for the discussion of the legislation s scope to this river; the identification of the types of soil s covering and evaluation the effectiveness of Law Nº.8426/2003, as protection instrument and land management. The river is characterized by its ecological importance and for feeding the Jiqui pond, an important reservoir that supplies 30% of drinking water to the east, west and south population sof the capital of the State. Pitimbu river is passing by a process of environmental degradation, originating from actions as deforestations of its ciliary forests by intensive agricultural practices; introduction of urban and industrial effluents leading to its contamination; increase of the pluvial drainage; erosion, sedimentation and discharge of urban waste , along with pressure for urban settlements along its banks. Under the methodological point of view is part of theoretical planning and land management research, and from a vision of social and environmental spaces. It was produced a survey map of the soil s covering, with 16 classes. Divided into coverage and disturbed natural covering. Using the 300 meters spatial limits of the Environmental Protection Strip, according to the State Law. The survey highlighted a higher percentage of classes disturbed, indicating man s interference in the balance of that system, as well as the lack of environmental actions. Leading to the degradation of riparian areas, and lack of conservation of water resources. Finally, it was considered that the strips of environmental protection are not effective as the preservation and territorial ordination

Análise isotópica (δ¹³C) e legalidade em néctares de uva

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)