Integridade estrutural de compósitos laminados em fibra de carbono sujeitos a diferentes taxas de desgaste e absorção de água : protótipo de máquina de testes

Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia MecânicaDesde sempre no panorama do ciclismo de alta competição se fizeram todos os esforços para melhorar os resultados dos atletas. Grande parte destes trabalhos está no desenvolvimento das bicicletas e seus componentes. A empresa Morphis Composites que está em fase de desenvolvimento de carretos de desviador em fibra de carbono. Estando estes componentes em material compósito laminado expostos à atmosfera, poderá estar em causa a sua integridade estrutural pois sabe-se que irão absorver água por difusão e se vão desgastar de forma diferente de carretos de outros materiais. Tudo isto poderá levar ao aumento do seu atrito na transmissão, sendo que é necessária a criação de meios para a avaliação desta temática. No presente trabalho faz-se o projecto e construção de um protótipo para medição de atrito em transmissões de bicicleta. Inclui-se uma breve pesquisa bibliográfica sobre correntes de rolos industriais e de ciclismo, o seu funcionamento e mecanismos de atrito. Além disto fez-se também uma breve pesquisa sobre os efeitos da absorção de água na fibra de carbono. Para o dimensionamento do sistema de medição procuraram-se resultados de trabalhos similares de forma a aferir as grandezas a medir e a sensibilidade necessária. O protótipo deve medir a potência conduzida à transmissão para esta rodar em vazio a uma velocidade constante que foi fixada neste caso em 60 rpm, sendo que quanto mais baixa a potencia medida menor o atrito da transmissão. O sensor usado é uma roseta colada a +45 e -45 graus no veio que fornece movimento ao sistema. O sinal é retirado do veio em rotação através de um sistema de anéis deslizantes em bronze onde se usaram escovas de grafite e de filamentos de cobre. Após a construção do protótipo fez-se a calibração estática dos sistemas de medição com bons resultados de sensibilidade e repetibilidade. Estes resultados empíricos também foram comparados com os resultados teóricos não tendo havido discrepâncias relevantes, provando a qualidade das medições de binário obtidas pelos extensómetros. No entanto, devido ao ruído introduzido no sinal pelas escovas em movimento, não foi possível obter resultados de qualidade nos ensaios dinâmicos para a potência e atrito na transmissão em rotação com o presente protótipo. No final apresentam-se sugestões para melhoria em trabalhos futuros.Ever since the beginning of high competition in cycling, that every erffort has been made to improve the results of the athletes. Much of this work is in the development of bicycles and their components. The company Morphis Composites is in the development stage of carbon fiber rear derailleur sprockets. These components made of laminated composite material are exposed to the atmosphere, thus their structural integrity may be affected because it is known that they will absorb water by diffusion and will wear differently from sprockets made of other materials, such as metals. All this can lead to the increase of its friction in the transmission, and it is necessary to create means for the evaluation of this situation. In the present work, the design and construction of a prototype for measuring friction in bicycle transmissions is done. A brief literature review on industrial roller and cycling chains, their operation and friction mechanisms is included. In addition, a brief research was also made on the effects of water absorption on carbon fiber. For the sizing of the measurement system, results of similar work were sought in order to understand the quantities to be measured and the required sensitivity. The prototype shall measure the power delivered to the transmission to idle at a constant speed which has been set at 60 rpm in this case, the lower the measured power the lower the transmission friction. The sensor used is a rosette glued to +45 and -45 degrees in a section of the main shaft before the main sprocket. The signal is drawn from the rotating shaft through a bronze slip ring system where graphite brushes and copper filaments were used. Upon prototype building the static calibration of the measurement systems was made with good results of sensitivity and repeatability. These empirical results were also compared with what would theoretically be expected and there were no relevant discrepancies, proving the quality of the torque measurements obtained by the extensometers. However, due to the noise introduced into the signal by the moving brushes, it was not possible to obtain quality results in the dynamic tests for power and friction in the rotational transmission with the present prototype. At the end, suggestions are presented for improvement in future work.N/

A survey for maintenance of virulent newcastle disease virus-free area in poultry production in Brazil

In 2003, Brazil was recognized as a pathogenic Newcastle Disease Virus (NDV) strain-free country for commercial poultry. This research was conducted in Brazil between December 2003 and March 2005 to verify the maintenance of this virulent NDV-free status. Serum samples from 5,455 flocks for commercial poultry farms were collected, comprising 81,825 broiler chickens. The farms were located in nine states of the country, grouped in three geographic regions. Serological evidence of NDV infection was detected in 28.8% of the surveyed farms. However, all fifteen viruses isolated and identified as Newcastle Disease Virus (NDV) were characterized as nonpathogenic strains, based on the Intracerebral Pathogenicity Index. These results showed that Brazil preserves the virulent NDV-free status for commercial flocks.368375Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Serum concentrations of acute phase proteins and immunoglobulins of calves with rotavirus diarrhea

ABSTRACT The aim of the present study was to characterize changes in acute phase protein levels according to the occurrence of rotavirus diarrhea in calves in the first month of life. Blood and fecal samples were taken before colostrum intake and at 1, 2, 7, 15, 21 and 30 days of age from 24 Holstein calves allotted in three experimental groups: calves that did not present diarrhea (group A), calves that presented diarrhea, but tested negative for rotavirus in feces (group B), and calves that presented diarrhea and tested positive for rotavirus in feces (group C) (experiment 1). When the animals presented episodes of diarrhea, blood and fecal samples were taken at 24-hour intervals until the end of clinical signs (experiment 2). Serum proteins were separated by SDS-PAGE technique and rotavirus in feces was detected by PAGE. Data of experiment 1 were analyzed by ANOVA and Tukey's test, considered significant at P<0.05. Data of experiment 2 were subjected to the HSD test. Total protein, globulins, and IgG concentrations were lower in group C than in groups A and B. Ceruloplasmin and transferrin levels were higher in group C than in groups A and B. Serum concentrations of haptoglobin and α1-acid glycoprotein did not differ significantly between groups throughout the experimental period. Calves presented diarrhea between 10.4 and 14.6 days of age in group B, and between 10.3 and 14.6 days of age in group C. In the moments of diarrhea manifestation, least square means of IgA, haptoglobin and α1-acid glycoprotein concentrations did not differ significantly between groups B and C, but ceruloplasmin and transferrin concentrations were higher in group C than in group B, as opposed to what occurred with IgG levels. These findings show that optimizing passive immunity transfer of immunoglobulins decrease the likelihood of calves developing diarrhea caused by rotavirus. In addition, ceruloplasmin presents characteristics of a biomarker of rotavirus infection in calves

A survey for maintenance of virulent newcastle disease virus-free area in poultry production in Brazil

In 2003, Brazil was recognized as a pathogenic Newcastle Disease Virus (NDV) strain-free country for commercial poultry. This research was conducted in Brazil between December 2003 and March 2005 to verify the maintenance of this virulent NDV-free status. Serum samples from 5,455 flocks for commercial poultry farms were collected, comprising 81,825 broiler chickens. The farms were located in nine states of the country, grouped in three geographic regions. Serological evidence of NDV infection was detected in 28.8% of the surveyed farms. However, all fifteen viruses isolated and identified as Newcastle Disease Virus (NDV) were characterized as nonpathogenic strains, based on the Intracerebral Pathogenicity Index. These results showed that Brazil preserves the virulent NDV-free status for commercial flocks.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq