Citotoxicidade de cimentos retrobturados experimentais em fibroblastos V79: [recurso eletrônico]

Combining the characteristics of good adhesion and sealing of the AH Plus sealer the biological properties of the MTA, zinc oxide and calcium hydroxide, the purpose of this study was to evaluate the cytotoxicity of these associations. The specimens of the sealers and their associations were mixed and exposure to culture medium (82.4 mm2surface/mL) after the manipulation and incubated in a humidified incubator (37°C and 100% humidity) for 24 h. Chinese hamster lung fibroblasts (V79) were exposed to different dilutions of this extracts for 24 h and cell viability was measured by MTT test. The differences between the cell survival rates were statistically analyzed for Kruskal-Wallis and Dunn (p≤0.05). All sealers showed a significant difference with the group control, except the MTA. Cytotoxicity with the control group increased in the following order: AH Plus < AH Plus + Ca(OH) 2 < AH Plus + OxZn< AH Plus + MTA < MTA (p≤ 0,05). It was concluded that the addition of biological materials in order to improve the consistency of AH Plus for use in retro cavities its toxicity has not decreased significantly

Estudo do potencial de associações de ZnO com os produtos naturais ácido cafeico e ferúlico como filtros solares híbridos: [recurso eletrônico]

In this work were studied associations of ZnO with the natural products caffeic and feluric acids. Two preparation methods were used, that is, the sol-gel and a reflux procedure. In the sol-gel method, ZnO is produced by the basics hydrolysis of precursors in the presence of the organic filters (caffeic and feluric acids), which results in 30 nm (or less) ZnO particles with the organic filters (in dissociated form) bonded to the surface of ZnO. In the reflux method, a dispersion of ZnO in a water/ethanol mixture was kept under reflux (50oC/4h) in the presence of the organic acids. The ZnO particles used in the reflux method have a higher diameter than sol-gel ZnO particles, but the prepared associated product ZnO/Organic acids were similar. Despite of the difference in relation to crystallinity between the products, the preparation methods resulted in analogous associations with respect to the interaction of the organic filters with the ZnO surface. The caffeic/ZnO associations presented low photostability, which lead to the degradation of the organic filter. The other associations (feluric acid/ZnO) presented satisfactory results. The FT-IR spectroscopy confirmed the formation of the association, and the nature of the bond formed compared with the Zn-O bond in Zn2+/Felutic acid complexes. The isolated organic and inorganic filters, along with the associations were analyzed by diffuse reflectance spectroscopy and Uv-vis spectroscopy. The absorption edges and the critical wavelengths were analyzed and the effects of Zn-O bonds in feluric acid/ZnO associations described as a function of the relative position of the π/π* system of the organic filter. Finally the performance of the hybrid filters were investigated in terms of the absorption of UVA and UVB radiations, with the UVA/UVB ratio, an efficiency parameter largely used in the description of solar filters, sunscreen and suncare products

Análise fractal de fraturas em regime linear elástico: modo I de carregamento

For the development of this graduate work of fractal fracture behavior, it is necessary to establish references for fractal analysis on fracture surfaces, evaluating, from tests of fracture tenacity on modes I, II and combined I / II, the behavior of fractures in fragile materials, on linear elastic regime. Fractures in the linear elastic regime are described by your fractal behavior by several researchers, especially Mecholsky JJ. The motivation of that present proposal stems from work done by the group and accepted for publication in the journal Materials Science and Engineering A (Horovistiz et al, 2010), where the model of Mecholsky could not be proven for fractures into grooved specimens for tests of diametric compression of titania on mode I. The general objective of this proposal is to quantify the distinguish surface regions formed by different mechanisms of fracture propagation in linear elastic regime in polymeric specimens (phenolic resin), relating tenacity, thickness of the specimens and fractal dimension. The analyzed fractures were obtained from SCB tests in mode I loading, and the acquisition of images taken using an optical reflection microscope and the surface topographies obtained by the extension focus method of reconstruction, calculating the values of fractal dimension with the use of maps of elevations. The fractal dimension was classified as monofractal dimension (Df), when the fracture is described by a single value, or texture size (Dt), which is a macroscopic analysis of the fracture, combined with the structural dimension (Ds), which is a microscopic analysis. The results showed that there is no clear relationship between tenacity, thickness and fractal values for the material investigated. On the other hand it is clear that the fractal values change with the evolution of cracks during the fracture process ... (Complete abstract click electronic access below)

Tratamento da superfície do alumínio via eletrólise a plasma

This paper presents the study on the application of the electrolytic plasma for surface treatment of aluminum. A bibliographical study on the material of interest was preliminarily performed and later designed and built an electrolytic cell, including the excitation source. Unlike conventional electrolysis process, the plasma assisted carry on in the non-linear region of characteristic current/voltage curve. Therefore it requires for the on set of the process that the power supply operates on harder conditions than those on high current process. The plasma produced during the present investigation has temperatures in the range o 6,0.10 3 -7,0 .10 3 K, well above those found in conventional chemical process. It also shows a particular dynamic to promote changes on surface and to produce new materials. The plasma is generated by microdischarge in vapor or gas bubbles involved in physic-chemical processes in electrode regions of the electrolytic cell. The electrode material was the aluminum (7075). The Process Electrolytic Plasma Processing (EPP) is sensitive to various parameters such as operating voltage, current density, electrolyte, concentration of electrolyte, geometry of reactor, temperature of electrolytic solution and dynamic of the fluid in the cell. The experiments were carried on in order to find parameters for a stable abd steady operation. The choice for the electrolytic was silicate/alkali solution in various concentrations to operate in various voltage as well. Plasma was produced on negative (cathode) and positive (anode) electrode, in specific conditions. A stable operation on the cathode process was obtained with low concentration of the electrolytic in aqueous solution, current density around 250V effective voltage. For the evolution of plasma in anodic process it was required higher concentrations and higher... (Complete abstract click electronic access below)

Análise estatística da vida em fadiga de compósitos estruturais pela distribuição de Weibull

Nowadays technological trend is based on finding materials that could support low weight with satisfactory mechanical properties and for this reason composite material became a very attractive topic in research projects all over the world. Due to its heterogenic properties, this type of material shows scatter in mechanical test results, especially in cyclic loading. Therefore it is important to predict its fatigue strength behaviour by statistic analysis, once fatigue causes approximately 90% of the failure in structural components. The present work aimed to investigate the fatigue behaviour of the Twill/Cycom 890 composite, which is carbon fiber reinforced with polymeric resin as matrix and manufactured via RTM process (Resin Transfer Molding). All samples were tested in different tensile level in triplicate in order to associate these values. The statistical analysis was conducted with Two-Parameter Weibull Distribution and then evaluated the fatigue life results for the composite. Weibull graphics were used to determine the scale and shape parameters. The S-N curve for the Twill/Cycom composite was drawn and indicated the number of cycles to occur the first damages in this material. The probability of failure was associated with material reliability, as shown in graphics for the different tensile levels and fatigue life. In addition, the laminate was evaluated by ultrasonic inspection showing a regular impregnation. The fractographic analysis conducted by SEM showed failure mechanisms for polymeric composites associated to cyclic loadings ... (Complete abstract click electronic access below)

Histologia comparada de brânquias, fígado e sangue em peixes da espécie Prochilodus lineatus, expostos a águas contaminadas

Os estudos hematológicos das diferentes espécies de peixes são de interesse ecológico e fisiológico, auxiliando na compreensão da relação entre as características sanguíneas, a filogenia, a atividade física, o hábitat e a adaptabilidade dos peixes ao ambiente. No experimento realizado foram testados os efeitos de águas contaminadas em parâmetros hematológicos de peixes da espécie Prochilodus lineatus, em períodos de coleta de 7 e 20 dias, nos quais o sangue foi coletado com seringas heparinizadas, foram montadas lâminas de esfregaço , as quais foram coradas pelo corante de Leishman. Estas lâminas foram analisadas e fotografadas com o auxílio de um microscópio óptico Leica, no qual foram feitas contagens totais de células brancas e contagens diferenciais de trombócitos e leucócitos, para a análise estatística. O grupo exposto ao Lago Azul apresentou uma elevação no número de leucócitos e no total de células brancas, evidenciando que os contaminantes químicos do ambiente estavam atuando de forma semelhante a um antígeno no corpo do animal fazendo com que suas células de defesa se proliferassem. Quanto ao grupo exposto ao detergente, observou-se que após os vinte dias de experimento ocorreu uma diminuição no número de trombócitos. Tais resultados evidenciam que a variação no número de leucócitos apresentou-se como um indicador de poluição ambiental e que os detergentes biodegradáveis podem em certo tempo de exposição ocasionar um déficit em funções vitais de peixes como à coagulação e a prevenção contra infecções, eventos ligados diretamente com os trombócitos. A maioria dos vertebrados aquáticos possui brânquias, estruturas especializadas nas trocas gasosas e responsáveis por grande parte das trocas iônicas. Este órgão acaba por absorver grande parte das substâncias presentes na água, que ao caírem na...(Resumo completo, clicar acesso eletrônico abaixo)

Avaliação in vitro da ação de substâncias químicas auxiliares, clorexidina e medicações intracanais sobre C. albicans, E. faecalis, E. coli e sua endotoxina em canais radiculares: [recurso eletrônico]

The purpose of this study was to evaluate the antimicrobial activity of chlorhexidine gel 2% as auxiliary chemical substance on the biomechanical preparation (BMP) and medication intracanal (ICM) on C. albicans, E. faecalis, E. coli and their endotoxin in root canals. We used 48 single-rooted human teeth divided into four groups according to dressing ICM: 1) Ca(OH)2 + pyrogen-free saline solution; 2) 2% chlorhexidine gel (CLX); 3) Ca(OH)2 + CLX, and; 4) pyrogen-free saline solution (control group). Were collected the contents of root canals to confirm the presence of microorganisms (confirmation), immediately after instrumentation (1st collection), after 7 days of the BMP (2nd collection), after 14 days of the action of ICM (3rd Collection) and 7 days after removal of the ICM (4 th collection). Were performed: the evaluation of antimicrobial activity and the content analysis of endotoxins for all sampling tests. The results were statistically analyzed using Kruskall-Wallis and Dunn tests with a significance of 5%. It was found that the CLX as auxiliary chemical substance has significantly reduced microorganisms confirmation collection when compared. In relation to the neutralization of endotoxin, it was found that the 1st and 2nd collections presented a decrease of 92.03% and 98.10% in mean percentage respectively, when compared to the confirmation collection. In the 3rd and 4th samplings, the Ca (OH)2 + CLX group showed the best results. It was concluded that the BMP and the ICM were able to eliminate the tested microrganisms, however, they were not able to completely eliminate endotoxins root canal

Desenvolvimento e caracterização de sistemas nanoestruturados para administração cutânea de metotrexato

A psoríase é uma doença inflamatória de pele e das articulações, e por acometer um órgão visível como a pele, resulta em transtornos psicológicos relacionados à auto-estima do paciente. Dentre os fármacos empregados no tratamento, destaca-se o metotrexato para uso sistêmico que, embora eficiente, possui a desvantagem de causar efeitos colaterais tóxicos como a hepatotoxicidade e a mielotoxicidade. Para minimizar tais efeitos e aumentar a eficácia do fármaco, o trabalho teve por objetivo desenvolver e caracterizar sistemas nanoestruturados para administração cutânea do metotrexato. Para realizar esse estudo, inicialmente foram preparadas diferentes formulações constituídas por silicone fluido de copolímero glicol (DC® 193), poliéter funcional siloxano (DC® 5329) e água destilada. O metotrexato foi incorporado numa concentração de 1,25% (p/v), com auxílio de solução de hidróxido de sódio 1M, sendo ajustado o pH final da formulação para 7,0 com ácido clorídrico 0,1M. Foram selecionadas algumas regiões do diagrama para serem submetidas a testes de estabilidade, empregando o teste de centrifugação, determinação do pH, condutividade iônica, índice de refração e avaliação das características organolépticas. Foi realizada a análise reológica empregando reômetro, modelo RS-1 (HaakeRheostress). As estruturas das formulações foram analisadas por microscopia de luz polarizada. As amostras com maior concentração de tensoativo apresentaram aspecto transparente, sendo submetidas à análise com microscópio de luz polarizada, onde evidenciou-se estruturas conhecidas como “cruzes de malta”, indicativas de fase lamelar. Foram selecionadas 3 formulações com concentração de 40% de tensoativo, variando-se as proporções de água e óleo, nas quais foram incorporadas o metotrexato... (Resumo completo, clicar acesso eletrônico abaixo)

Expansão ex vivo de células uroteliais em scaffolds 3D

Malformations and possible damages to the urogenital system can be originated in the embryonic period. Moreover, fire guns, knives and accidents, where there is the disruption of the urethra, also cause these lesions. The objective was to analyze the contribution of tissue engineering in the construction of neo-urethra, developed by bioengineering. We performed an urothelial ex vivo expansion of cells in 3D scaffolds (platelet gel matrix and acellular porcine aorta) to assess the contribution of this technique in the construction of a neo-urethra. Mechanical dissociation was made of the inner wall of 10 North Folk rabbit’s bladder, weighing 2.5 to 3.0 kg. After dissociation the cell content was centrifuged and obtained a pellet of urothelial cells. The pellet was ressuspended in culture medium DMEM F12 and cells were maintained in culture for 15 days. Immunohistochemical analysis characterized the urothelial culture. The cells were then implanted in the scaffold - platelet gel. In a second experiment using aortic porcine acellular matrix were implanted urothelial cells alone and urothelial cells on platelet gel, on the inner wall of the scaffold - aorta, with space for setting bordered by a urethral probe. The complex probe - cells - aorta and probe - cells in platelet gel - aorta, were sealed with suture material and culture were maintained in a humidified 37ºC incubator with 5% CO2 in air for 12 days to subsequent histological analysis of urothelium cell adhesion to the scaffolds. By observation under an optical microscope, we could see the growth of cells in the scaffold platelet gel, from a monolayer in to a three-dimensional structure. In the acellular porcine aortic matrix containing the platelet gel, we could observe a few quantity of urothelial cells adhered. However with the acellular porcine aortic matrix in which was implanted only the urothelial cells, we have obtained adhesion to the wall

Efeito da plataforma vibratória na recuperação da densidade óssea de ratas ovariectomizadas

As mudanças demográficas decorrentes do envelhecimento populacional têm contribuído substancialmente para o aumento de doenças crônicas não transmissíveis relacionadas à idade, dentre elas está a osteoporose, considerada um dos principais problemas de saúde pública, por sua prevalência crescente e pela associação a fraturas em diversas áreas do corpo, com graves repercussões clínicas e sociais. Com isso vem se buscando cada vez mais alternativas de exercício físico válidas para o combate e prevenção a estas doenças ósseas. Como possível alternativa têm se estudado os efeitos e benefícios dos treinamentos realizados em Plataformas Vibratórias, equipamento que através de baixa amplitude e alta freqüência pode vir a influenciar positivamente nas capacidades físicas. Portanto, devido à escassez de informações acerca dos efeitos do exercício na plataforma vibratória sobre a microarquitetura dos ossos em indivíduos idosos e já acometidos pela osteoporose, o objetivo deste estudo foi, com um modelo animal, descrever através de imagens de Microscopia Eletrônica de Varredura (MEV), a reação do tecido ósseo de ratas idosas ovariectomizadas ao exercício em Plataforma Vibratória. Para execução deste estudo foram utilizadas 20 ratas Wistar (Rattus Norvegicus Albinus Wistar), separadas em 4 grupos: Sedentário Controle (S), Sedentário Ovariectomizado (SO), Treinado Controle (T) e Treinado Ovariectomizado (TO). Como protocolo de treinamento a plataforma vibratória foi regulada com freqüência de 35 Hz e amplitude baixa (1 a 2 mm) e consistiu de uma fase de adaptação ao exercício e à vibração e após este período uma fase de treinamento. Para análise a região do osso selecionada foi o terço proximal da diáfise do fêmur. Como resultado, obtivemos que para o grupo SO a indução à osteoporose foi positiva quando comparada ao grupo S, que ...(Resumo completo, clicar acesso eletrônico abaixo)

Estudo de cerâmicas avançadas para fins de blindagem balística

The research involving new materials has always been considered as a differential in the development of a technology company. This occurred naturally since ancient times, often motivated by reasons of a certain age, where the most common material used was also the name of your time and may be cited as an example the Bronze Age, and later was the Iron. Currently, the use of firearms are they used in resolving conflicts between countries, or a more equivocal, as an instrument of social banditry make innovations in the area of shielding welcome, whether for personal use, in the form of vests or vehicle such as cars, tanks and even aircraft. In this context, is a Silicon Carbide Ceramic, with low density and high hardness. Thus, the aim of this study is the evaluation and comparison of these materials, seeking to improve their properties by means of additives such as boron and silicon metal and amorphous YAG. For this work, the specimens were pre-shaped by means of uniaxial later to be referred for isostatic pressing and sintering. The maximum percentage for each additive was 5%, except for the YAG whose percentage was 8.2% (mass percentage). All compositions were subjected to the same tests (x-ray diffraction, apparent density, optical microscopy, Vickers hardness, scanning electron Microscopita), so that one could draw a comparison between the materials under study, samples that showed better mechanical properties and micro structural, related here by hardness testing and microscopy (optical and SEM) were the silicon carbide doped with YAG and alumina samples, demonstrating the potential of these materials for ballistic protection. Other compositions have high porosity, which is highly undesirable, since in order to harmful influences on the mechanical properties discussed below

Estudo da superfície de fibras de carbono após tratamento de implantação iônica por imersão em plasma (3IP)

In this work, plasma immersion ion implantation (PIII) treatments of carbon fibers (CFs) were performed in order to induce modifications of chemical and physical properties of the CF surface aimed to improve the performance of thermoplastic composite. The samples to be treated were immersed in nitrogen or air glow discharge plasma and pulsed at −3.0 kV for 2.0, 5.0, 10.0, and 15.0 min. After PIII processing, the specimens were characterized by atomic force microscopy (AFM), scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). After CFs treatments, the CF/Polypropylene (PP) composites were produced by hot pressing method. Surface morphology of as-received CFs exhibited some scratches aligned along the fibers due to the fiber manufacturing process. After both treatments, these features became deeper, and also, a number of small particles nonuniformly distributed on the fiber surface can be observed. These particles are product of CF surface sputtering during the PIII treatment, which removes the epoxy layer that covers as-received samples. AFM analyses of CF samples treated with nitrogen depicted a large increase of the surface roughness (Rrms value approximately six times higher than that of the untreated sample). The increase of the roughness was also observed for samples treated by air PIII. Raman spectra of all samples presented the characteristic D- and G-bands at approximately 1355 and 1582 cm−1, respectively. Analysis of the surface chemical composition provided by the XPS showed that nitrogen and oxygen were incorporated onto the surface. The polar radicals formed on the surface lead to increasing of the CF surface energy. Both the modification of surface roughness and the surface oxidation contributed for the enhancement of CF adhesion to the polymeric matrix. These features were confirmed ... (Complete abstract click electronic access below)

Comportamentos, térmico e mecânico, de compósitos de polipropileno e resíduo da hidrólise enzimática do bagaço de cana de açúcar

Pós-graduação em Engenharia Mecânica - FEG

Desenvolvimento de recobrimento submicrométrico de óxido de nióbio para aplicação em tubulações de prospecção de petróleo

Pós-graduação em Engenharia Mecânica - FEG

Processo de reparo ósseo diante de três tipos de superfície de titânio: análise histomorfométrica e por microscopia eletrônica de varredura associada ao EDS: estudo experimental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)