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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

[en] STUDY OF THE FATIGUE STRENGTH OF STEELS SUBJECTED TO COMBINED LOADS FORMED BY PLANE FLUCTUATING BENDING AND CONSTANT TORQUE / [pt] UM ESTUDO SOBRE A RESISTÊNCIA A FADIGA DOS AÇOS SUBMETIDOS A CARREGAMENTOS COMBINADOS DE FLEXÃO PLANA FLUTUANTE COM TORQUE CONSTANTE

JOSE GONCALVES DE ALMEIDA 30 August 2012 (has links)
[pt] O presente trabalho se refere a uma anáise experimental da influência das pré cargas de flexão e torção combinadas, na resistência à fadiga dos aços quando submetido a uma flexão plana variável. Verificou-se que as pré cargas de flexão e troção combinadas tem pouca influência na resistência a fadiga para vidas (10)3 menor que N menor que 10 ciclos. Nesta faixa a maior influência foi de 13,97 por cento correspondendo a uma vida n mais (10)3 ciclos e uma pré carga uniaxial equivalente o m igual a 45,8 kgf/mm2, Todavia, para uma vida n maior que 5x10 ciclos não se verifiou nenhuma influência com pré cargas variando de 0 a 63,7 kgf/mm2. Por meio de testes de hipótese, com uma confiança Y igual a 90 por cento, constatou-se que não existe influência com pré cargas quando 17,4 menor que o mi menor que 63,7 kgf/mm2. Isto se deu para qualquer valor de N entre (10)3 e 10 ciclos. A teoria de falha adotada foi a teoria da máxima energia de distorção aplicada, separadamente, as componentes alternadas e médias. O corpo de prova utilizado tem um acabamento superficial de retificação fina, uma concentração de tensão a fadiga de 1,1 por cento (que foi considerada desprezível) e um diâmetro digual a 6 mais ou menos 0,5 mm na secção efetiva. O carregamento na região efetiva é de flexão pura tanto para a pré carga de flexão quanto para a componente alterada. Na análise estatística dos resultados utilizou-se a função de distribuição de Weibull, de grande aplicação no estudo de fadiga. A máquina utilizada faz parte deste trabalho e é de concepção original. / [en] This work consit in na experimental analysis about the influence of combined bending and torsion preloading in fatigue strength of steels, under variable plane bending. It has been shown that combined bending and torsion preloading has little influence in fatigue strength for lifes (10)3 less than N less than 10 cycles. In this range, the most significant influence is 13,97 per cent, corresponding to (10)3 cycles and an quivalent axial preloading 0 m 4 equal 45,8 kgf/ mm. However, for a life n more than 5x 10 cycles we have found no influence with preloading from zero zero to 63,7 kgf /mm. Using hypothesis testes, with 90 per cent confidence level, we have proved that there is no influence of preoloading when 17,4 less than mi less than 63,7 kgf / mm. This has been observed for any life N between (10)3 and 10 cycles. The maximum distortion energy theory was adopted as a flailure theory, applied to alternating and medium components separately. It was used a test specimen with fine ground surface finishing fatigue stress concentration factor 1,1 per cent (neglected) effective cross section in bending for preloading and for the alternating component. In the final statistical analysis it was the Weibull distribution fuction. The fatingue machine was specially designed in our laboratory to obtain the necessary data.
132

Investigation of Mode Superposition as Modelling Approach for Crankshaft Torsion

Johansson, Jonas January 2018 (has links)
With tougher emission standards for heavy duty trucks, good control of the engine is of importance. By taking into consideration the torsional vibrations occurring in the crankshaft, the engine control can be improved. This could be done by implementing a torsion model that would give feedback to the engine control unit to reduce the cycle-to-cycle variations in the cylinders, which is partly due to the torsion in the crankshaft. It is therefore of interest to determine if a torsion model can be developed with a reduced computational complexity and still have sufficient accuracy. In this thesis a model was developed in Matlab for estimation of torsion in the crankshaft of an inline 6 cylinder diesel engine. By applying Newtons second law, the equations of motion that describe the torsional vibrations in the crankshaft were set up. The equations of motion were transformed using modal analysis and with the use of mode superposition it was investigated how reducing the number of vibrational modes in the model, affected the models accuracy in its estimation of torsion. Two model reductions were evaluated where the first three and four vibrational modes were used to calculate the torsional displacement between the flywheel and the cylinders. Using measured pressure curves for a number of operating points of the engineas input to the model, results were produced for different crank angle intervalsshowing deviations between the developed torsion models and a reference models estimation of torsion. Due to the damping approximation used in the model, high initial deviations could be found at certain operating points beforereducing the number of vibrational modes. These initial deviations weregreatest for the first two cylinders. Results from the model reductions showed that using the first three vibrational modes in the torsion model, is sufficient for estimating the torsional displacement between the flywheel and all cylinderswith an accuracy of within 0.1 degrees, with the exception of the first two cylinders for the early and late combustion interval.
133

Torção natural em nanotubos de carbono de parede simples / Natural Torsion on Sigle Wall Carbon Nanotubes

Verçosa, Daniel Gomes January 2012 (has links)
VERÇOSA, Daniel Gomes. Torção natural em nanotubos de carbono de parede simples. 2012. 80 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-16T21:41:19Z No. of bitstreams: 1 2012_dis_dgvercosa.pdf: 3436247 bytes, checksum: 0a1188195cc191e1fbc8767d711104c7 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-21T20:37:48Z (GMT) No. of bitstreams: 1 2012_dis_dgvercosa.pdf: 3436247 bytes, checksum: 0a1188195cc191e1fbc8767d711104c7 (MD5) / Made available in DSpace on 2015-10-21T20:37:48Z (GMT). No. of bitstreams: 1 2012_dis_dgvercosa.pdf: 3436247 bytes, checksum: 0a1188195cc191e1fbc8767d711104c7 (MD5) Previous issue date: 2012 / A mais recente revolução tecnológica vem surgindo através de avanços na área da nanotecnologia, onde se destacam materiais nanométricos como os nanotubos de carbono de parede simples (SWNTs). Esse novo material, descoberto em 1993, têm gerado grande interesse acadêmico e industrial devido às suas propriedades físicas únicas. Trabalhos recentes indicam que essas propriedades são extremamente sensíveis a diversos tipos de deformação estruturais, como aquelas de natureza axial, radial e torcional. Neste trabalho estudamos teoricamente como a estrutura eletrônica dos SWNTs, e consequentemente suas propriedades, reagem à presença de torção. Utilizamos o modelo Tight-Biding estendido (ETB) para calcular a estrutura de bandas dos tubos. A simulação de torção é feita a partir de vínculos específicos que altera a componente angular dos vetores primitivos da rede do grafeno. Para obtermos a configuração mais estável dos SWNTs, utilizamos um método denominado gradiente simples modificado de modo a minimizarmos sua energia total. Foi observado que nanotubos quirais apresentam um valor de torção diferente de zero, denominada torção natural, no seu estado fundamental. Essa torção decresce, de forma universal, com o inverso do cubo do diâmetro. Por sua vez, a dependência da torção natural com o ângulo quiral varia de acordo com a metalicidade do SWNT. As energias de transição ótica para o tubo naturalmente torcionado e não torcionado são comparadas, sendo observado variações de até 50% no minigap de tubos metálicos. Por fim, discutimos quais as possíveis implicações da presença da torção natural na ciência por trás dessa nanoestrutura de carbono.
134

The Functional Morphology of the Primate Zygomatic Arch in Relation to Diet

January 2017 (has links)
abstract: Craniofacial morphology in primates can vary on the basis of their diet because foods are often disparate in the amount and duration of force required to break them down. Therefore diet has the potential to exercise considerable selective pressure on the morphology of the masticatory system. The zygomatic arch is a known site of relatively high masticatory strain and yet the relationship between arch form and load type is relatively unknown in primates. While the relative position and robusticity of the arch is considered a key indicator of craniofacial adaptations to a mechanically challenging diet, and central to efforts to infer diet in past species, the relationships between morphology and diet type in this feature are not well established. This study tested hypotheses using two diet categorizations: total consumption percent and food material properties (FMPs). The first hypothesis that cortical bone area (CA) and section moduli (bone strength) are positively correlated with masticatory loading tests whether CA and moduli measures were greatest anteriorly and decreased posteriorly along the arch. The results found these measures adhered to this predicted pattern in the majority of taxa. The second hypothesis examines sutural complexity in the zygomaticotemporal suture as a function of dietary loading differences by calculating fractal dimensions as indices of complexity. No predictable pattern was found linking sutural complexity and diet in this primate sample, though hard object consumers possessed the most complex sutures. Lastly, cross-sectional geometric properties were measured to investigate whether bending and torsional resistance and cross-sectional shape are related to differences in masticatory loading. The highest measures of mechanical resistance tracked with areas of greatest strain in the majority of taxa. Cross-sectional shape differences do appear to reflect dietary differences. FMPs were not correlated with cross-sectional variables, however pairwise comparisons suggest taxa that ingest foods of greater stiffness experience relatively larger measures of bending and torsional resistance. The current study reveals that internal and external morphological factors vary across the arch and in conjunction with diet in primates. These findings underscore the importance of incorporating these mechanical differences in models of zygomatic arch mechanical behavior and primate craniofacial biomechanics. / Dissertation/Thesis / Appendix A / Appendix B / Appendix D / Doctoral Dissertation Anthropology 2017
135

Can an insole measure torsion in two different types of prosthetic feet?

Hjálmarsson, Bjarki January 2018 (has links)
Introduction: There have not been any prosthetic feet available that can match an intact foot in functionality. Little focus has been on research on prosthetic foot performance in frontal plane motions and while most have investigated sagittal plane motions. Background: Normal gait is an artform of falling, thus the intact anatomical foot needs to be capable of handling a wide-range of environments. A prosthesis is an external helping aid for amputees, therefore they lack the ability to adapt to different environments. Most of the researches on prosthetic feet have focused on the sagittal plane, which has limited understanding and literature towards frontal plane motions. In this study a relatively new insole measuring system was used, Vebitosolution. The Vebitosolution insole has five separate sensors. It’s made from a flexible, specially shaped material to allow the sensors to measure independently, and measures both bending and torsional moments. Aim: The aim of the study to investigate if the Vebitosolution system is capable of measure torsional moments in frontal plane during straight line walk in two different types of prosthetic feet. Method: The participants were two transtibial amputees of that used the same size and category foot. They walked in a straight line with two different prosthetic feet. Results: There was a statistical significant difference (P < 0,05) for all measurements except for one (P > 0,05). Discussion: The results give indications that the Vebitosolution system is capable in differentiating between two different types of prosthetic feet. There are also indications of both product and gait specific gait pattern, but further researches are needed.  This research is limited by its sample size and amount of measurements performed. Conclusion: The take-away from this research is that the Vebitosolution system might be capable of measuring differences in frontal plane moments in two different types of prosthetic feet. / Inledning: Fram tills idag har det inte funnits en protesfot som kunnat matcha en intakt anatomisk fot. Det har lagts betydligt mindre fokus på hur väl en protesfots rörelse fungerar i frontal plan jämfört med i sagittal plan. Bakgrund: Normal gång är konsten att hindra från att falla och den anatomiska foten behöver anpassa sig till ett brett spektrum av miljöer för att upprätthålla balans. En protes är ett externt hjälpmedel, de som är amputerad saknar därför förmågan att anpassa sig till olika miljöer. Störst fokus har varit att granska protes fötter i sagittalplanet, och därför saknas förståelse och litteratur för rörelser i frontalplanet. I den här studien användes ett relativt nytt mätinstrumentssystem genom inlägg från Vebitosolution. Vebitosolution inlägget har fem separata sensorer och är tillverkad i ett flexibelt och specialformat material. Designen möjliggör att sensorerna mäter självständigt och mäter både böjnings- och vridmonent. Syfte: Syftet med studien är att undersöka om Vebitosolution systemet kan mäta vridmoment i frontplanet under gång i en rak linje för två olika typer av protes fötter. Metod: Studien har undersökt två deltagare vilka båda varit amputerade på transtibial nivå och som använt sig av samma storlek och kategori av fot. De båda gick i en rak linje med två olika protes fötter. Resultat: Undersökningen visade att det var statistiskt signifikant skillnad (P <0,05) för alla mätningar utom för en (P> 0,05). Diskussion: Resultaten ger indikationer att Vebitosolution systemet kan differentiera mellan två olika typer av protes fötter. Det finns också indikation att det finns både produkt- och användarspecifikt gångmönster, men ytterligare undersökningar behöver göras. Denna forskning är begränsad av dess stickprovstorlek och mängden mätningar som utförts. Slutsats: Slutsatsen från denna forskning är att det finns en indikation på att Vebitosolution systemet kan mäta skillnaden i frontplan med avseende på vridmoment för två olika typer av protes fötter.
136

In vivo acute changes in ATP and glucose concentrations in the rat testicles following unilateral torsion: experimental study / Estudo experimental das alteraÃÃes agudas na glicemia e concentraÃÃes testiculares de ATP e glicose induzidas por torÃÃo unilateral, in vivo

SÃrgio Botelho GuimarÃes 04 April 2002 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Spematic cord torsion is one of the more common surgical urological emergencies in childhood. An experimental study has been conducted to investigate acute changes in testicular concentrations of ATP and glucose following one-hour unilateral 720 testicular torsion. Sixty prepubertal male Wistar rats were distributed into two groups: Group 2(Ischemia) and Group 1(Sham operated). Each group(n=30) was divided into 5 subgroups (n=6). All animals were subjected to right testicular torsion of 720Â. The testicular torsion of animals from Group 1 was immediately corrected. Group 2 animals had their testicular torsion lasting one hour followed by detorsion. Testicles were collected and arterial blood samples taken from abdominal aorta of each animal subgroup at the and of ischemic period or one hour after sham operation and 0.5, 1,6 and 24 hours later. ATP and glucose concentrations were significantly decreased (p<0,05) in ischemia group as compared to sham group at the end of ischemic period. There was no difference in glycemia when comparing ischemic versus sham-operated rats. Glucose concentrations were significantly increase (p<0,05) in ipsilateral testis of sham-operated rats No significant change in ATP and glucose concentrations were found in the left testicle in comparasion to the ones measured in the rigth testicle of the same animal. The decrease in ATP and glucose concentrations may be explained by the reduction in blood flow to the torted testis imposed by torsion. The absence of significant contralateral alterations in the concentrations of ATP and glucose could be related to the limited time of isquemia imposed to the right testis. It is concluded that unilateral one-hour testicular torsion causes a decrease in ipsilateral testicular perfusion resulting in decresead testicular concentrations of glucose and ATP in the ipstelial (right) testicles and no alterations in the concentrations of glucose and ATP in the contraleral testicles. Simple testicle manipulation (Sham Operation) causes a signficant increase in glucose concentrations in the ipsilateral(right)testis. / A torÃÃo do cordÃo espermÃtico à a emergÃncia geniturinÃria mais comum na idade pediÃtrica. Foram estudadas as alteraÃÃes metabÃlicas agudas nas concentraÃÃes testiculares de ATP e glicose apÃs uma hora de isquemia induzida por torÃÃo do cordÃo espermÃtico. Sessenta ratos wistar machos prÃ-pÃberes, foram distribuÃdos em 2 grupos de 30 animais cada e cada grupo em 5 subgrupos de 6 ratos. Os ratos do grupo 1 foram submetidos à torÃÃo seguida por distorÃÃo imediata (cirurgia simulada) do testÃculo direito. Os animais do grupo 2 foram submetidos à torÃÃo do testÃculo direito (720o) durante uma hora. Os animais dos diferentes subgrupos foram sacrificados 30 minutos, 1 hora, 6 horas e 24 horas apÃs a distorÃÃo ou realizaÃÃo da cirurgia simulada para a remoÃÃo dos testÃculos e coleta de amostra de sangue arterial. As alteraÃÃes das concentraÃÃes de glicose e ATP foram determinadas por mÃtodos enzimÃticos. Ocorreu queda significante (p<0,05) da concentraÃÃo de glicose e ATP no tempo 0 h, nos testiculos isquemiados. NÃo ocorreram alteraÃÃes na glicemia nem nas concentraÃÃes de glicose e ATP nos testÃculos contralaterais. Os animais submetidos à cirurgia simulada apresentaram aumento significante (p< 0,05) da concentraÃÃo de glicose no testÃculo ipsilateral quando comparada à concentraÃÃo de glicose no testÃculo esquerdo dos mesmos animais nos tempos 0 h e 24h. A diminuiÃÃo do fluxo sangÃÃneo em decorrÃncia da torÃÃo explica a reduÃÃo das concentraÃÃes de ATP e glicose nos testÃculos isquemiados. A ausÃncia de alteraÃÃes nas concentraÃÃes de ATP e glicose nos testÃculos contralaterais (esquerdos) poderia ser uma decorrÃncia do reduzido tempo de isquemia imposto ao testÃculo ipsilateral (direito). Concluiu-se que a torÃÃo testicular unilateral de 720o, por uma hora, induz uma reduÃÃo significante (p < 0,05) das concentraÃÃes testiculares de ATP e de glicose no testÃculo isquemiado sem alteraÃÃes correspondentes da glicemia. A simples manipulaÃÃo do testÃculo direito (cirurgia simulada) induz um aumento da concentraÃÃo de glicose testicular.
137

Torção de Reidemeister das formas espaciais esféricas / Reidemeister torsion of spherical space forms

Thiago de Melo 17 March 2009 (has links)
Neste trabalho, estudamos a ação dos grupos dos quatérnios generalizados \'Q IND.4t\', nas esferas, com o objetivo de calcularmos a torção de Reidemeister dos espaços quocientes, chamados de Formas Espaciais Esféricas Quaterniônicas. Calculamos a torção de Ray-Singer das esferas, dos espaços lenticulares e do cone sobre as esferas, este último fornecendo o caso particular do disco, usando a base para a homologia definida em [27]. Para as variedades fechadas, obtivemos a torção analítica por meio do Teorema de Cheeger-Müller [7, 22], e para o disco, por meio de uma fórmula provada por Brüning e Ma em [5] / In this work, we study the action of the generalized quaternionic groups \'Q IND.4t\' on the spheres to compute the Reidemeister torsion of the quotient spaces, which are called Quaternionic Spherical Space Forms. Using the base of the homology defined by Ray and Singer in [27] we compute also the Ray-Singer torsion of the spheres, lens spaces and the cone over the spheres. This last one provides the disc as a particular case. For the closed manifolds we obtain the analytic torsion using the Cheeger-Müller Theorem [7, 22] and for the disc using a formula proved by Brüning and Ma in [5]
138

Estudo biomecânico do comportamento de diferentes espessuras de capa de cimento ósseo em novo modelo de prótese modular diafisária femoral em cão submetidas a ensaio de torção / Biomechanical analysis in the use of different cement layers in a new model of modular diaphyseal femoral implant relative to torsion forces

Marcos Ishimoto Della Nina 17 December 2008 (has links)
A viabilidade da utilização de próteses modulares cimentadas em diáfises de fêmur em cães foi demonstrada, porém diversos autores relatam a falha de aderência entre as próteses e os ossos como uma das principais complicações. O presente trabalho teve como objetivo investigar biomecanicamente a interface implante metálico, osso e capa de cimento ósseo de com diferentes espessuras de cimento ósseo utilizadas para a estabilização da prótese. Para tanto foram utilizados fêmures bilaterais de 24 cadáveres de cães com peso acima de 15 quilos que foram divididos em quatro grupos, o primeiro grupo composto por oito fêmures utilizou uma espessura de capa de cimento de 1,0 a 1,5 mm, o segundo grupo, composto por oito fêmures, utilizou uma capa de cimento de 2,0 a 2,5 mm e o terceiro grupo, composto por oito fêmures, utilizou uma capa de cimento compreendida entre o intervalo de 3,0 a 3,5 mm de espessura. Os fêmures foram submetidos a ensaios destrutivos de torção onde foram avaliados a rigidez à torção e torque máximo suportado pela interface implante metálico, osso e capa de cimento ósseo. O quarto grupo, denominado de controle, composto pelos fêmures contralaterais íntegros, foram submetidos ao mesmo ensaio de torção que as peças onde foram utilizadas as próteses. Os resultados encontrados foram que nas condições apresentadas neste estudo não foi encontrada diferença biomecânica estatisticamente significante, em relação à rigidez à torção e torque máximo, na utilização de capas de cimento na faixa de 1 mm e 2,5 mm e entre 2 mm e 3,5 mm. Porém houve diferença quando comparado as faixas de espessura de cimento entre os grupos de 1 mm a 1,5mm e de 3 mm a 3,5 mm. / The feasibility of modular cemented prosthesis in the femoral diaphysis was demonstrated in dogs, but several authors report loosening of bone, cement and implant interface as a major complication. The objective of this study was to evaluate the stabilization of the prosthesis using different thicknesses of cement layer. For this study 48 femurs from 24 dogs weighing over 15 kilograms were used. They were separated in four groups, the first group with eight femurs used a cement mantle from 1.0 to 1.5 mm, the second group, with eight femurs, used a cement mantle from 2.0 to 2.5 mm and the third group, with eight femurs, used a cement layer from 3.0 to 3.5 mm. The femurs were submitted to destructive torsion tests where they were evaluated due to the values of torsional rigidity and maximum torque shown by the implant, bone and bone cement interface. In the fourth group were the remaining intact femurs, they were evaluated using the same torsion test used on the other groups. The results were that under the present conditions we found no biomechanical differences relative to torsional rigidity and maximum torque, using cement layers between 1 mm and 2.5 mm and between 2 mm and 3.5 mm. But we found biomechanical differences between groups of 1 mm to 1.5 mm and 3 mm to 3.5 mm.
139

Estudo da ação da clorpromazina na torção testicular em ratos / Role of chlorpromaxine in a model of testicular torsion

Rafael Carvalho Mesquita 23 May 2016 (has links)
Introdução: A torção testicular permanece como uma emergência urológica, despertando grande interesse em fármacos que podem minorar a lesão testicular e suas repercussões na fertilidade e produção hormonal. No entanto, não há fármaco aprovado para uso clínico rotineiro. Uma droga estudada em isquemia celular é a clorpromazina, sendo conhecidos seus efeitos protetores na função e estrutura da membrana celular e mitocondrial. Objetivos: Avaliar a diferença na lesão de células germinativas após 1 e 6 horas de torção e a ação da clorpromazina administrada previamente à resolução da torção no testículo isquêmico. Materiais e Métodos: 54 ratos Wistar, machos, com peso corporal entre 220 e 260 gramas distribuídos em 5 grupos: sham, controle com isquemia de 1 hora(A), controle com isquemia de 6 horas(B), experimental com isquemia de 1 hora(C) e experimental com isquemia de 6 horas(D). Em 48 animais foi realizada torção unilateral do cordão espermático com duas voltas em torno do seu eixo (720 graus), fixando-se o testículo nessa posição, após o que cada subgrupo foi separado em avaliação imediata (orquiectomia bilateral ao final do período de torção = 1) e tardia (orquiectomia bilateral, uma semana após a resolução da torção = 2). O grupo experimental recebeu 3 mg/kg de clorpromazina administrada via endovenosa, 30 minutos antes da resolução da torção. O grupo controle recebeu apenas solução salina a 0,9% por via endovenosa. Outros 6 animais formaram o grupo sham, onde foi realizada apenas a manipulação do cordão espermático. Após retiradas as gônadas, foram preparadas para análise histológica pela microscopia de luz e imunohistoquímica.Um pequeno fragmento de cada testículo foi separado para avaliação por microscopia eletrônica de transmissão (MET). Resultados: Na análise por microscopia de luz foram notadas alterações devido à isquemia como, necrose de coagulação e edema intersticial, principalmente nos grupos com isquemia mais prolongada (6h - B e D). Na avaliação por imunohistoquímica, houve maior expressão da caspase-3 nas células e túbulos dos testículos com 6 horas de isquemia, quando comparados com o grupo sham. No entanto, a expressão de bcl-2 não foi expressiva em nenhum grupo. Os grupos B e D também demonstraram alterações mais expressivas na análise por MET. Em nenhuma das avaliações foi observado superioridade do grupo da clorpromazina em relação ao grupo controle. Conclusão: As lesões celulares intratubulares induzidas pela isquemia e reperfusão testicular foram semelhantes após 1 e 6 horas, as diferenças foram relacionadas à sua maior intensidade no grupo com 6 horas e a clorpromazina não foi efetiva na prevenção da lesão por reperfusão. / Introdution: Testicular torsion remains as a urology emergency arousing interest about medicine which can reduce testicular injury and its impact on fertility and hormone production. However, there is no drug approved for routine clinical use. A drug studied in cell ischemia is chlorpromazine, being known its protective effects on the function and structure of cellular membrane and mitochondrial. Objective: To evaluate the difference in lesion of germ cells after 1 and 6 hours and the action of chlorpromazine administered before the resolution of ischemic testicle due torsion. Materials and methods: 54 male Wistar rats weighing between 220 to 260 grams divided into five groups: sham, control with one hour of ischemia (A) control with six hours of ischemia (B) experimental with one hour of ischemia (C) and experimental six hours of ischemia (D). In 48 animals was performed unilateral torsion of the spermatic cord with two laps around its axis (720 degrees), keeping the testicle in this position. After that, each subgroup was divided into immediate evaluation (bilateral orchiectomy at end of the torsion period = 1) or later (bilateral orchiectomy after one week of torsion resolution = 2). The experimental group received 3 mg / kg chlorpromazine administered intravenously 30 minutes before the resolution of torsion. The control group received only saline 0.9% intravenously. Other 6 animals were in the sham group, which was held just handling the spermatic cord. After withdrawal, the gonads were prepared for histological analysis by light microscopy and immunohistochemistry. A small piece of each testis was separated for evaluation by electron microscopy. Results: In analysis by light microscopy, ischemic changes were rated as coagulative necrosis and interstitial edema mainly in groups with prolonged ischemia (6h - B and D). When analyzed by immunohistochemistry, there was greater expression of caspase-3 in cells and tubules of the testes with 6 hour of ischemia compared to the sham group. However, bcl-2 expression was not impressive in either group. B and D groups also showed more significant changes in the analysis by electron microscopy. None of the ratings has been shown superiority of chlorpromazine group over the control group. Conclusion: The germ cell damage induced by ischemia and reperfusion was similar after 1 and 6 hours, the differences were related to its greatest intensity in the group with 6 hours and chlorpromazine was not effective in preventing reperfusion injury.
140

Distributed temperature sensing and non-contact torsion measurement with fibre bragg gratings

Kruger, Ludi 26 February 2009 (has links)
M.Ing. / This thesis demonstrates the measurement of temperature distribution across a metal plate and the non-contact measurement of torsion in a rotating shaft. After a thorough theoretical study of the origin of fibre Bragg gratings, methods of fabrication and erasing of gratings, methods of demodulating the signals from gratings, and methods of discriminating between strain and temperature variations in gratings, simulations and experiments were done to prove the feasibility of both temperature distribution measurement and non-contact torsion measurement. For the measurement of temperature distribution, a 450 x 450 x 1.6 mm type 304 stainless steel plate was used. Two 4,7Ω 25W resistors were used as heat sources, and five fibre Bragg gratings measured the temperature at strategic points on the plate. The measured values were interpolated appropriately and a three-dimensional representation of the temperature distribution was shown on a personal computer monitor. The measurement of torsion was first done on a non-rotating 25 mm diameter solid shaft with torque applied. Both resistive strain gauges and fibre Bragg gratings were attached to the shaft and the measurement results compared well. Up to 90 Nm of torque was applied to the shaft. The non-contact measurement of torsion on a rotating shaft was done with fibre Bragg gratings and involved the use of graded index (GRIN) lenses for transmitting optical information between the light source, the gratings, and back to the spectrum analyser through free space. A special Böhler steel with high yield strength was used, and the set-up was mounted on a lathe. The one end of the shaft was clamped in the lathe chuck, and the other was fixed to an automobile drum brake system, allowing the application of torque on the rotating shaft. Up to 97 Nm of torque was applied to the shaft rotating at 190 rpm, and the results are within 10% of the expected values. As far as we are aware, this is the first time that torsion is measured by fibre Bragg gratings without the need to have physical contact with the shaft, i.e. slip rings, to transmit the information to and from the sensors. The experimental results of this thesis confirm that fibre Bragg grating sensors can be applied usefully in temperature distribution measurement, as well as in the measurement of torsional stress in rotating shafts.

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