625 resultados para Permuta de resinas aniónicas e fenólicas


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A exposição in utero a xenoestrógenos pode aumentar o risco de neoplasias de natureza endócrina na vida adulta. O Bisfenol A (BPA), componente de resinas e plástico, considerado xenoestrógeno e desregulador endócrino, tem sido investigado pelos seus potenciais efeitos adversos para a saúde humana. Como a Genisteína e o Indol-3-Carbinol possuem propriedades que podem inibir neoplasias de natureza endócrina, é possível que também atuem modulando/modificando os efeitos causados pela exposição gestacional ao BPA. O presente projeto teve como objetivos: (1) Avaliar os efeitos da exposição gestacional ao Bisfenol - A (BPA) sobre a morfogênese do útero e ovários na prole de fêmeas Sprague-Dawley (SD) da geração F1; (2) Avaliar se a exposição gestacional a genisteína e ao indol-3-carbinol altera os efeitos do BPA sobre sobre a morfogênese do útero e ovários na geração F1 e (3) avaliar os efeitos da exposição ao BPA, e às associações BPA e genisteína, BPA e indol-3-carbinol em relação à susceptibilidade a carcinogênese induzida pela N-Metil-N-Nitrosuréia (MNU). Portanto, fêmeas prenhas da linhagem SD foram divididas em 7 grupos experimentais e expostas ao Bisfenol A (BPA) (25 ou 250 ug/kg p.c.) DG 10 até o DG 21 (Moral et al. 2008), além de ração basal ou ração contendo genisteína (250 mg/kg) ou indol-3-carbinol (2000 mg/kg) durante toda a gestação. Parte da prole Fêmeas SD foi sacrificada parte no Dia Pós-Natal (DPN) 21 e parte ao final da 25ª semana após iniciação ou não com a MNU. Ao DPN 21 os ovários e útero foram removidos para contagem de folículos e morfometria, respectivamente. A prole restante de fêmeas recebeu uma única dose de MNU (50 mg/kg) ou solução de NaCl (1 ml/kg) no DPN 51 e foi sacrificada na 25ª semana após a aplicação de MNU ou de NaCl. Ovários e útero foi removidos para análises histológicas, incluindo a determinação de lesões proliferativas ...

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The weight of a vehicle has always been considered an extreme important factor, because it interferes in the performance, steering, consume, environmental impact, wear of components, among the others. Because of the new demand, consume reduction aim and gases emission increased the necessity to manufacture lighter vehicles, guaranteeing the complying with the gas emission international law. Besides the legal demand, the low weight will certainly be essential for the competitiveness for the next generation of vehicles. It is with this thinking the composite materials have been introduced in the automobilist industry, because those materials show an excellent relation of strength/weight, providing a reduction of consume and the increase of load capacity. Those factors justify the increase of interest of industry and the necessity of optimization of those materials and of their process. For this research, the field of application will be the Baja SAE Project, a project that is fully developed by engineering students, where they build a prototype single seat, off-road category, for use on hilly slopes with obstacle. This research aims to study two key components of the prototype are made of composite materials, analyzing all the processing. In addition, there is the analysis of the viability of this production parts to a Baja SAE vehicle, in order to increase their performance and reduce their weight without reducing the safety and robustness of the prototype. It was possible to achieve weight reduction of the steering subsystem with manufacturing the flywheel hybrid composite (carbon/glass) and the replacement of SAE 1010 steel by hybrid composite (carbon/aramid) in CVT box. The importance of this study is to obtain a good project for the vehicle of technical and scientific manner, contributing to the know-how to the team and providing a basis for optimization for upcoming projects

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In order to study resin distribution and homogeneity of composite laminates manufactured by RTM, it was used CYCOM 890 monolithic toughened epoxy as a matrix with two different configurations of intermediated modulus (IM) carbon fibers: Satin Weave (5HS) and non crimp fabric (NCF). The injection parameters were defined based on Thermo Gravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and rheological analysis. After processing the material, the resin/fiber impregnation was studied using ultrasonic test, Thermo Gravimetric Analysis, Differential Scanning Calorimetry, Dynamic Mechanical Analysis (DMA) and flexural tests. Therefore, it was able to observe an internal residual stress during the cooling process in both laminates, higher in the composite using NCF fabric due to the lack of symmetry, although a good proportion of fiber/matrix has been verified by the lower values of flexural modulus deviation. The DMA enabled the visualization of glass transition and its association with the inter and intra molecular interaction and movement, in which the NCF composite presented better permeability due to the lowest temperature of glass transition, when compared to the Satin Weave composite

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Due to growing concerns for reducing environmental damage caused by the use of non-renewable raw materials, there is a growing demand for research related to aggregate technology with environmental preservation. Thus, the use of non-renewable materials and less aggressive materials has been gaining attention. About composite materials, the exchange of synthetic fibers by natural fibers, especially vegetable fiber as reinforcement, has been increasing, due to its physical-chemical properties such as mechanical strength, nontoxic, low cost, low density, processing flexibility, non-abrasive to the process equipment, requiring simple surface treatments, etc. This objective was to process composites reinforced with long fibers of sapegrass in epoxy matrix and characterize the composites through mechanical tests. Three groups of composites were prepared according to the treatment received by the reinforcement: without treatment, alkali treatment at concentration of 5% w/v and alkali treatment at 10% w/v concentration. The materials were analyzed by tensile and flexural, and tests also optical microscopy and scanning electron microscopy (SEM). The results were statistically analyzed. As the main result, the alkali treatment of 5% in the sapegrass fibers increases the tensile and flexural strength, as a consequence of the improve adhesion between matrix and reinforcement

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Engenharia Civil - FEIS

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Pós-graduação em Engenharia Mecânica - FEG

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Molar-Incisor Hypomineralization (MIH) is a qualitative developmental enamel defect that affects one to four permanent first molars, with or without involvement of permanent incisors. Enamel defects may produce many symptoms that have physical, social and psychological effects and influence day-to-day living or quality of life. The available treatment modalities for teeth with MIH are extensive, ranging from prevention, restoration, to extraction. Factors such as age, patient expectations, severity of the lesion and materials should be considered in the treatment of the patient with MIH. Restoration with composite resin is an alternative choice for posterior and anterior MIH defective teeth and its use has been show acceptable results. This article describes two clinical cases involving pediatric patients with MIH whose procedure of cavity preparation was based on the use of CVD ultrasound diamond tips and restored using composite resin obtaining favorable esthetics results after a 1 year follow-up.

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Following the introduction of the acid-etching technique in enamel surface, direct attachment of orthodontic appliances on the surface of the tooth and/or restorations became a routine procedure in the assembly of the fixed devices. The attainment of a success result is related to the criterion attention to the details and the steps of the bonding technique, as well as, to the knowledge of the characteristics of the adhesive materials and orthodontic brackets. This paper presents some aspects of various types of brackets and adhesives materials.

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Direct bonding of orthodontics attachments to the teeth or restoration has become a routine in fixed appliance therapy. The technique used seems to be simple, but meticulous attention to detail and steps, a thorough understanding of factors involved are needed to ensure a successful outcome into different surfaces. It is the purpose of this article to review concerning aspects to orthodontic bonding in enamel and restorations fabricated from different materials; affording assistance to the reader wiser accomplishment and successful procedure.

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Immediate functioning of osseointegrated implants has been widely employed in edentulous patients due to its safety and high predictability. However, viability and success of immediate-loaded implants is defined by factors such as number of implants, distribution and splinting, as well as reduction of oblique loads and excessive occlusal contacts. The indirect composite resin-modified glass enable building of a highly aesthetic prosthesis, combining satisfactory resistance and better force dissipation on occlusal loading. This article describes a resin composite, mandibular fixed prosthesis on osseointegrated implants in immediate function.