A maioria dos patógenos responsáveis pelas principais doenças do milho (Zea mays L.) é transmitida pelas sementes, trazendo consequências como a podridão de sementes e o tombamento de plântulas, redução da germinação e do vigor, diminuindo assim a qualidade das sementes de milho. Este trabalho teve por objetivo avaliar a patogenicidade, transmissão e incidência de Fusarium verticilliodes em sementes de milho oriundas de espigas inoculadas com diferentes métodos. No presente trabalho foram realizados testes de detecção de F. verticillioides para confirmação da presença do patógeno nas plantas de milho inoculadas nas formas de spray, injetável e natural. Foi avaliada a porcentagem de emergência, qualidade fisiológica e sanitária de sementes de milho produzidas com diferentes graus de infecção por F. verticillioides, relacionando-se com a produtividade. Foi possível identificar a sensibilidade das técnicas de PCR, que amplificaram as concentrações de DNA testadas. A técnica de PCR utilizada foi capaz de detectar até 1% de infecção. Foi observado que as inoculações feitas nas espigas das plantas com spray resultaram em maior incidência do patógeno nas sementes quando comparada aos demais tratamentos. Os dez híbridos inoculados apresentaram incidência de F. verticillioides nas sementes que foram submetidas às três formas de inoculação. Quanto à emergência das plântulas verificou-se porcentagem superior à 90% em todos os híbridos estudados. / Most of the pathogens responsible for the main diseases of maize (Zea mays L.) are transmitted by seeds, with consequences such as seed rot and seedling tipping, germination and vigor reduction, thus reducing the quality of maize seeds. The objective of this work was to evaluate the pathogenicity, transmission and incidence of Fusarium verticilliodes in corn seeds from spikes inoculated with different methods. In the present work, Fusarium verticillioides detection tests were performed to confirm the presence of the pathogen in maize plants inoculated in spray, injectable and natural forms. The percentage of emergence, physiological and sanitary quality of maize seeds produced with different degrees of infection by F. verticillioides was evaluated, being related to productivity. The PCR technique used was able to detect up to 1% of infection. It was observed that the inoculations on the spikes of the spray plants resulted in a higher incidence of the pathogen in the seeds when compared to the other treatments. The ten inoculated hybrids showed incidence of F. verticillioides in the seeds that were submitted to all forms of inoculation. To verify the transmissibility of the seed pathogen to the plants, after extractions of leaf and stem tissues, DNA extraction analyzes with specific primer of F. verticillioides were made. Seedling emergence showed a percentage higher than 90% in all hybrids studied.

Esse trabalho visa estudar a influência da vibração no desempenho de tarefas de pilotos de aeronaves. Para o seu desenvolvimento, foi montada uma bancada usando um assento de aeronave para avaliar a transmissibilidade da vibração vertical para os pilotos e verificar se níveis elevados de aceleração, como no caso de falha da turbina, podem prejudicar sua habilidade em desempenhar tarefas de leitura, escrita e digitação. Todos os experimentos foram realizados com sucesso, comprovando grande parte dos estudos anteriores sobre o assunto. Ainda são apresentadas comparações relacionando os mesmos níveis de aceleração usados no teste de transmissibilidade, com as normas ISO 2631-1 e ANSI S3.18 para avaliação da exposição humana à vibração de corpo inteiro, que são as mais apropriadas para a correlação com o mundo aeronáutico. / This work aims to study the influence of vibration in aircraft pilots task performance. For the study development, it was assembled a rig test using an aircraft pilot seat, in order to evaluate the transmissibility of vertical vibration to the pilots and to verify if high acceleration levels, as in the case of engine failure, are of significance to the pilots ability in performing tasks such as reading, writing and typing. All the experiments were accomplished successfully, confirming most of early studies about the subject. Comparisons are also presented, relating the same acceleration levels used in the transmissibility test with ISO 2631-1 and ANSI S3.18 standards for evaluation of human exposure to whole-body vibration which are the most appropriated for correlation with the aeronautical world.

The present work introduces novel methodologies for damage detection and health monitoring of structural and mechanical systems. The new approach uses the angular velocity inside different mathematical forms, via a gyroscope, to detect, locate, and relatively quantify damage. This new approach has been shown to outperform the current state-of-the-art acceleration-based approach in detecting damage on structures. Additionally, the current approach has been shown to be less sensitive to environmental acoustic noises, which present major challenges to the acceleration-based approaches. Furthermore, the current approach has been demonstrated to work effectively on arch structures, which acceleration-based approaches have struggled to deal with. The efficacy of the new approach has been investigated through multiple forms of structural damage indices. The first methodology proposed a damage index that is based on the changes in the second spatial derivative (curvature) of the power spectral density (PSD) of the angular velocity during vibration. The proposed method is based on the output motion only and does not require information about the input forces/motions. The PSD of the angular velocity signal at different locations on structural beams was used to identify the frequencies where the beams show large magnitude of angular velocity. The curvature of the PSD of the angular velocity at these peak frequencies was then calculated. A damage index is presented that measures the differences between the PSD curvature of the angular velocity of a damaged structure and an artificial healthy baseline structure. The second methodology proposed a damage index that is used to detect and locate damage on straight and curved beams. The approach introduces the transmissibility and coherence functions of the output angular velocity between two points on a structure where damage may occur to calculate a damage index as a metric of the changes in the dynamic integrity of the structure. The damage index considers limited-frequency bands of the transmissibility function at frequencies where the coherence is high. The efficacy of the proposed angular-velocity damage-detection approach as compared to the traditional linear-acceleration damage-detection approach was tested on straight and curved beams with different chord heights. Numerical results showed the effectiveness of the angular-velocity approach in detecting damage of multiple levels. It was observed that the magnitude of the damage index increased with the magnitude of damage, indicating the sensitivity of the proposed method to damage intensity. The results on straight and curved beams showed that the proposed approach is superior to the linear-acceleration-based approach, especially when dealing with curved beams with increasing chord heights. The experimental results showed that the damage index of the angular-velocity approach outweighed that of the acceleration approach by multiple levels in terms of detecting damage. A third methodology for health-monitoring and updating of structure supports, which resemble bridges’ bearings, is introduced in this work. The proposed method models the resistance of the supports as rotational springs and uses the transmissibility and coherence functions of the output response of the angular velocity in the neighborhood of the bearings to detect changes in the support conditions. The proposed methodology generates a health-monitoring index that evaluates the level of deterioration in the support and a support-updating scheme to update the stiffness resistance of the supports. Numerical and experimental examples using beams with different support conditions are introduced to demonstrate the effectiveness of the proposed method. The results show that the proposed method detected changes in the state of the bearings and successfully updated the changes in the stiffness of the supports.

The lack of adequate equipment and measurement tools in whole-body vibration has imposed significant constraints on what can be measured and what can be investigated in the field. Most current studies are limited to single direction measurements while focusing on simple postures. Besides the limitation in measurement, most of the current biomechanical measures, such as the seat-to-head transmissibility, have discrepancies in the way they are calculated across different labs. Additionally, this field lacks an important measure to quantify the subjective discomfort of individuals, especially when sitting with different postures or in multiple-axis vibration. This work begins by explaining discrepancies in measurement techniques and uses accelerometers and motion capture to provide the basis for more accurate measurement during single- and three-dimensional human vibration responses. Building on this concept, a new data collection method is introduced using inertial sensors to measure the human response in whole-body vibration. The results indicate that measurement errors are considerably reduced by utilizing the proposed methods and that accurate measurements can be gathered in multiple-axis vibration. Next, a biomechanically driven predictive model was developed to evaluate human discomfort during single-axis sinusoidal vibration. The results indicate that the peak discomfort can be captured with the predictive model during multiple seated postures. The predictive model was then modified to examine human discomfort to whole-body vibration on a larger scale with random vibrations, multiple postures, and multiple vibration directions. The results demonstrate that the predictive measure can capture human discomfort in random vibration and during varying seated postures. Lastly, a new concept called effective seat-to-head transmissibility is introduced, which describes how to combine the human body's biodynamic response to vibration from multiple directions. This concept is further utilized to quantify the human response using many different vibration conditions and seated postures during 6D vibration. The results from this study demonstrate how complicated vibrations from multiple-input and multiple-output motions can be resolved into a single measure. The proposed effective seat-to-head transmissibility concept presents an objective tool to gain insights into the effect of posture and surrounding equipment on the biodynamic response of the operators. This thesis is timely as advances in seat design for operators are increasingly important with evolving armrests, backrests, and seat suspension systems. The utilization of comprehensive measurement techniques, a predictive discomfort model, and the concept of effective seat-to-head transmissibility, therefore, would be beneficial to the fields of seat/equipment design as well as human biomechanics studies in whole-body vibration.

Resumo: A cárie dentária pediátrica continua sendo uma doença significativa em países em desenvolvimento. A presença de microrganismos cariogênicos na saliva materna pode favorecer a contaminação de seu filho. O desenvolvimento das lesões é fortemente dependente do momento em que ocorreu a infecção; quando precoce, a prevalência de cárie é maior. Detectar a transmissão vertical do S. mutans e S. sobrinus e relação com o micro ambiente bacteriano, índice de cárie e cuidados maternos. Amostra: 60 crianças, ambos os gêneros, de um a três anos de idade e suas respectivas mães. Técnicas utilizadas: PCR e Nested- PCR. Indices de cárie: CPO-D e ceo. Instrumentos: exame clínico e questionário aplicado às mães. Registrou-se: ceo, CPO-D, higiene bucal, cuidados e hábitos de carinho. Resultados. Houve concordância de ausência e de presença de Streptococcus mutans e sobrinus entre mães e filhos, com diferença estatísticamente significante (p<0,05), tanto na placa como na saliva; índices de cárie igual a zero somente em 38,33% das crianças e 10% das mães; maior freqüência de respostas das mães para a questão sobre o não uso de fio dental, duas escovações diárias, visita ao dentista com intervalo de seis meses e prova do alimento do filho com a própria colher. As técnicas PCR e Nested PCR se mostraram adequadas para a detecção de Streptococcus. Houve concordância dos resultados dos filhos e suas respectivas mães quanto à presença/ausência de microrganismos S. sobrinus e S. mutans na placa e saliva, sugerindo a transmissibilidade vertical. Detectou-se um menor índice de cárie dos filhos em relação às suas mães. O Índice de cárie das crianças foi superior ao esperado pela OMS para 2010 e os hábitos de higiene/carinhos relatados pelas mães eram inadequados para com seus filhos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Dental caries in children is still an expressive disease .The presence of cariogenic microorganisms on maternal saliva might favor contamination of their children. The development of caries lesions is strongly related to the time when infection takes place; the sooner, the higher the caries prevalence. To detect S.mutans and S.sobrinus vertical transmissibility and its relation with bacterial microenvironment, caries index and maternal care. Sample: composed of 60 children of both genders, aging from one to three years, with their respective mothers. Employed techniques: PCR and Nested-PCR. Caries indexes: DMFT and dmft. Instruments: clinical exam and questionaires applied to mothers. Assessed: DMFT, dmft, oral hygine, care and affection habits. Results: There was a correlation between the presence or absence of Streptococcus mutans and sobrinus of mothers and respective children, being statistically different (P<0.05) both on dental plaque and saliva The caries index was equal to zero in 38.33% of children and 10% of mothers. Not flossing, tooth brushing twice a day, appointment with a dentist every 6 months and tasting their children's food with the same spoon were the answers more frequently observed. PCR and Nested PCR techniques were adequate to detect Streptococcus mutans in saliva and dental plaque. The microorganisms' detection was similar, both in saliva and dental plaque, and a correlation on the results of children and their respective mothers regarding presence/absence of S.sobrinus and S.mutans on either dental plaque or saliva was observed, confirming vertical transmission. A lower caries index was observed in children in relation to their respective mothers, although being higher than the WHO 2010 guidelines. The hygiene/affection habits related by mother were inadequate to their children... (Complete abstract click electronic access below) / Orientador: Maria Inês de Moura Campus Pardini / Coorientador: Nidia Alice Pinheiro / Banca: Solange O. Braga Franzolin / Banca: Leila Maria Vieira / Banca: Izabel M. M. Carvalho / Banca: Ana Lucia Capelozza / Doutor

Nowadays, whole-body vibration is widely recognized as risk factor for worker all around the world. Most of published works on this subject was developed in main research centers. The aims of this study were (1) to determine the vertical whole-body vibration levels on the tractor seat, (2) to determine the combination influence between three tire inflation pressures and two travel speed in the whole-body vibration, (3) to characterize the vertical whole-body vibration high level in one-third-octave band, (4) to determine the transmissibility between the seat and the seat support, (5) to compare the values with ISO 2631 (1997) Standard. A vertical whole-body vibration levels field measurement was accomplished with a 65 kW tractor and a seeder-fertilizer. Three tire inflation pressures P1 = 179 kPa, P2 = 138 kPa and P3 = 96 kPa and two travel speed V1 = 4,5 km/h and V2 = 7 km/h were used in this study. The results revealed that (1) the lowest acceleration weighting was 0,68 m/s² (P1 x V1) and de highest acceleration weighting was 3,32 m/s² to (P1 x V2), (2) the whole-body vibrations, the travel speed, the tire inflation pressure and it s interaction have influenced on the vertical whole-body vibration, (3) the vertical whole-body vibration high level in one-third-octave band was 4 at 8 Hz by combination (P1, P2 and P3) with (V2), excepted for (P2 x V2) by 5 Hz, (4) the lowest SEAT% weighting by combination (V1) with (P1) and (P2), (5) the pressure and speed combination resulted in whole-body vibrations levels which characterize the operator seat from fairly uncomfortable to extremely uncomfortable. The best scenario was (P1 x V1), because the tractor operator was submitted to acceptable vertical whole-body vibration levels. / Hoje em dia, vibrações ocupacionais são amplamente reconhecidas como fator de risco para os trabalhadores em todo o planeta. A maioria dos trabalhos publicados sobre este assunto são desenvolvidos em grandes centros de pesquisa. Os objetivos deste estudo foram (1) determinar os níveis de vibrações verticais no assento do trator, (2) determinar a influência da combinação entre três pressões de insuflagem e duas velocidades de deslocamento nas vibrações ocupacionais, (3) caracterizar a faixa de freqüência que apresenta os maiores picos de vibração vertical no assento do operador do trator, (4) determinar os valores da transmissibilidade entre o suporte do assento e o assento, (5) comparar os resultados encontrados com os valores exigidos com a norma técnica ISO 2631 (1997). Foram realizadas medições de vibrações ocupacionais (verticais) a campo com um trator de 65 kW e uma máquina de semeadura e adubação. Três pressões de insuflagem P1 = 179 kPa, P2 = 138 kPa e P3 = 96 kPa e duas velocidades de deslocamento V1 = 4,5 km/h e V2 = 7 km/h foram usadas neste estudo. Os resultados revelaram que (1) o mais baixo valor de MAPG foi de 0,68 m/s² para (P1 x V1) e o mais alto valor de MAPG foi de 3,32 m/s² para (P1 x V2), (2) as pressões de insuflagem, as velocidades de deslocamento e a sua interação influenciaram nas vibrações ocupacionais, (3) as faixas de freqüência que apresentaram os maiores picos de vibração foram de 4 a 8 Hz na combinação entre as três pressões com a velocidade (V2), exceto para (P2 x V2) na freqüência de 5 Hz que ficou abaixo do limite de 8 horas de exposição, (4) o menor valor de SEAT% foi na combinação entre a velocidade (V1) com as pressões (P1) e (P2), (5) a combinação das pressões com as velocidades resultou em níveis de vibrações ocupacionais que caracterizam o assento do operador de razoavelmente desconfortável até extremamente desconfortável. O melhor cenário foi (P1 x V1), pois o operador esteve exposto a magnitudes de vibrações aceitáveis.

Made available in DSpace on 2014-06-11T19:32:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-26Bitstream added on 2014-06-13T20:42:58Z : No. of bitstreams: 1 marafiotti_gapp_dr_botfm.pdf: 232028 bytes, checksum: 9028f7cfb913afa87c099ddf2e6179bd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cárie dentária pediátrica continua sendo uma doença significativa em países em desenvolvimento. A presença de microrganismos cariogênicos na saliva materna pode favorecer a contaminação de seu filho. O desenvolvimento das lesões é fortemente dependente do momento em que ocorreu a infecção; quando precoce, a prevalência de cárie é maior. Detectar a transmissão vertical do S. mutans e S. sobrinus e relação com o micro ambiente bacteriano, índice de cárie e cuidados maternos. Amostra: 60 crianças, ambos os gêneros, de um a três anos de idade e suas respectivas mães. Técnicas utilizadas: PCR e Nested- PCR. Indices de cárie: CPO-D e ceo. Instrumentos: exame clínico e questionário aplicado às mães. Registrou-se: ceo, CPO-D, higiene bucal, cuidados e hábitos de carinho. Resultados. Houve concordância de ausência e de presença de Streptococcus mutans e sobrinus entre mães e filhos, com diferença estatísticamente significante (p<0,05), tanto na placa como na saliva; índices de cárie igual a zero somente em 38,33% das crianças e 10% das mães; maior freqüência de respostas das mães para a questão sobre o não uso de fio dental, duas escovações diárias, visita ao dentista com intervalo de seis meses e prova do alimento do filho com a própria colher. As técnicas PCR e Nested PCR se mostraram adequadas para a detecção de Streptococcus. Houve concordância dos resultados dos filhos e suas respectivas mães quanto à presença/ausência de microrganismos S. sobrinus e S. mutans na placa e saliva, sugerindo a transmissibilidade vertical. Detectou-se um menor índice de cárie dos filhos em relação às suas mães. O Índice de cárie das crianças foi superior ao esperado pela OMS para 2010 e os hábitos de higiene/carinhos relatados pelas mães eram inadequados para com seus filhos... / Dental caries in children is still an expressive disease .The presence of cariogenic microorganisms on maternal saliva might favor contamination of their children. The development of caries lesions is strongly related to the time when infection takes place; the sooner, the higher the caries prevalence. To detect S.mutans and S.sobrinus vertical transmissibility and its relation with bacterial microenvironment, caries index and maternal care. Sample: composed of 60 children of both genders, aging from one to three years, with their respective mothers. Employed techniques: PCR and Nested-PCR. Caries indexes: DMFT and dmft. Instruments: clinical exam and questionaires applied to mothers. Assessed: DMFT, dmft, oral hygine, care and affection habits. Results: There was a correlation between the presence or absence of Streptococcus mutans and sobrinus of mothers and respective children, being statistically different (P<0.05) both on dental plaque and saliva The caries index was equal to zero in 38.33% of children and 10% of mothers. Not flossing, tooth brushing twice a day, appointment with a dentist every 6 months and tasting their children’s food with the same spoon were the answers more frequently observed. PCR and Nested PCR techniques were adequate to detect Streptococcus mutans in saliva and dental plaque. The microorganisms’ detection was similar, both in saliva and dental plaque, and a correlation on the results of children and their respective mothers regarding presence/absence of S.sobrinus and S.mutans on either dental plaque or saliva was observed, confirming vertical transmission. A lower caries index was observed in children in relation to their respective mothers, although being higher than the WHO 2010 guidelines. The hygiene/affection habits related by mother were inadequate to their children... (Complete abstract click electronic access below)

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Wenjun Ma / Influenza A virus (IAV) is an enveloped, segmented, negative-sense RNA virus that infects avian species and mammals. Its segmented feature enables antigenic shift which can generate novel IAVs that pose a threat to animal and public health due to lack of immunity to these viruses. Pigs have been considered the “mixing vessels” of influenza A viruses to generate novel reassortant viruses that may threaten animal and public health. Therefore, it is necessary to understand the pathogenicity and transmissibility of newly emerged reassortant viruses in swine. Adding to this complexity is the newly identified bat influenza A-like viruses which have roused interest in understanding the evolutionary history and pandemic potential of bat influenza. At least 10 different genotypes of novel reassortant H3N2 IAVs with gene(s) from 2009 pandemic H1N1 [A(H1N1)pdm09] have been identified in pigs in the United States. To date, only three genotypes of these viruses have been evaluated in animal models leaving the pathogenicity and transmissibility of the other seven genotype viruses unknown. We showed that reassortant viruses with genes from A(H1N1)pdm09 are pathogenic and transmissible in pigs. Further studies showed that avian-like glycine at position 228 of the HA receptor binding site is responsible for inefficient transmission of the reassortant H3N2 IAV with five A(H1N1)pdm09 genes. Studying the recently discovered IAV-like sequences from bats has been hindered by the lack of live virus isolation or culturing. Using synthetic genomics, we successfully rescued modified bat influenza viruses that had the HA and NA coding regions replaced with two classical IAVs. Additional studies were performed with truncations on NS1 protein and substitution of a putative virulence mutation in bat influenza PB2. Virus reassortment experiments demonstrated that bat influenza has limited genetic and protein compatibility with other influenza viruses; however, it readily reassorts with another divergent bat influenza virus. Taken together, our results provide insights into the pathogenicity and transmissibility of novel reassortant H3N2 IAVs in pigs. It also indicates that the bat influenza viruses recently identified are viable viruses that pose little pandemic threat to humans. Moreover, they provide new insights into the evolution and basic biology of influenza viruses.

Esse trabalho visa estudar a influência da vibração no desempenho de tarefas de pilotos de aeronaves. Para o seu desenvolvimento, foi montada uma bancada usando um assento de aeronave para avaliar a transmissibilidade da vibração vertical para os pilotos e verificar se níveis elevados de aceleração, como no caso de falha da turbina, podem prejudicar sua habilidade em desempenhar tarefas de leitura, escrita e digitação. Todos os experimentos foram realizados com sucesso, comprovando grande parte dos estudos anteriores sobre o assunto. Ainda são apresentadas comparações relacionando os mesmos níveis de aceleração usados no teste de transmissibilidade, com as normas ISO 2631-1 e ANSI S3.18 para avaliação da exposição humana à vibração de corpo inteiro, que são as mais apropriadas para a correlação com o mundo aeronáutico. / This work aims to study the influence of vibration in aircraft pilots task performance. For the study development, it was assembled a rig test using an aircraft pilot seat, in order to evaluate the transmissibility of vertical vibration to the pilots and to verify if high acceleration levels, as in the case of engine failure, are of significance to the pilots ability in performing tasks such as reading, writing and typing. All the experiments were accomplished successfully, confirming most of early studies about the subject. Comparisons are also presented, relating the same acceleration levels used in the transmissibility test with ISO 2631-1 and ANSI S3.18 standards for evaluation of human exposure to whole-body vibration which are the most appropriated for correlation with the aeronautical world.

Orientador: Paulo José Paupitz Gonçalves / Resumo: O modelo de Zener, também conhecido como o modelo SLS, do inglês (Standard Linear Solid), é um modelo simples que descreve o comportamento de um material viscoelástico como isolador de vibração, utilizando uma combinação linear de molas e amortecedores para representar componentes elásticos e viscosos, respectivamente. Sabe-se que, o modelo mais semelhante de Maxwell, que é uma mola em série com um amortecedor, e o modelo de Kelvin-Voigt, que é uma mola em paralelo com um amortecedor, são utilizados. No entanto, estes modelos são muitas vezes insuficientes para representar tal comportamento desejado, o modelo de Maxwell não descreve a fluência ou recuperação, e o modelo de Kelvin-Voigt não descreve o stress e o relaxamento. O SLS é o modelo mais simples, que prevê dois fenômenos, com isso em mente, esta tese propõe a investigação do modelo de amortecimento de Zener substituindo as molas simples por molas não lineares (mola Duffing), no que diz respeito ao comportamento de isolamento de vibração, mostrando as curvas de transmissibilidade para vários valores de parâmetros. São utilizados métodos analíticos aplicáveis a sistemas não lineares, bem como método numérico para realizar análises de transmissibilidade do modelo de Zener e também o desenvolvimento de um aparato experimental que representa o modelo de isolador de vibração de Zener, essencial para um entendimento substancial dos fenômenos envolvidos. O objetivo principal da tese é investigar oportunidades de melhoria de i... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Zener model, also known as the solid linear standard model (SLS), is a simple model that describes the behavior of a viscoelastic material as a vibration isolator, using a linear combination of springs and dampers to represent elastic and viscous components , respectively. Often the most similar Maxwell model, which is a spring in series with a damper, and the Kelvin-Voigt model, which is a spring in parallel with a damper, are used. However, these models are often insufficient to represent such behavior, the Maxwell model does not describe fluency or recovery, and the Kelvin-Voigt model does not describe stress and relaxation. The SLS is the simplest model, which predicts two phenomena, with this in mind, this thesis proposes the investigation of the Zener damping model replacing the simple springs with non-linear springs (Duffing spring), with respect to the vibration isolation behavior, showing the transmissibility curves for various parameter values . Analytical methods will be used for non-linear systems, as well as a numerical method to carry out Zener model transmissibility analyzes, as well as the development of an experimental apparatus that represents Zener’s vibration isolator model, which is essential for a substantial understanding of the phenomena involved. The main objective of the thesis is to investigate opportunities for improvement of mechanical isolators when designed to act in dynamic bands with non-linear responses. / Doutor