Thesis (M.S.)--University of Michigan, Ann Arbor, 1978. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 141-148).

Thesis (M.S.)--University of Michigan, Ann Arbor, 1984. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 96-108).

Thesis (M. Phil.)--University of Hong Kong, 2000. / Includes bibliographical references.

Thesis (Ph. D.)--University of Nevada, Reno, 2008. / "December 2008." Includes bibliographical references (leaves 201-211). Online version available on the World Wide Web.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Anne S. Robinson, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (M.S. in materials science and engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Mar. 3, 2009). "Department of Mechanical and Materials Engineering." Includes bibliographical references.

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Orientador: Luis Alexandre Maffei Sartini Paulillo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T22:01:59Z (GMT). No. of bitstreams: 1 Barreto_SuelemChasse_M.pdf: 116094135 bytes, checksum: 14295d9814cd8a3d1872c717dd154522 (MD5) Previous issue date: 2015 / Resumo: O estudo teve como objetivo avaliar a influência da quantidade de primer usada na hibridização do substrato na resistência de união por microtração, nanoinfiltração e adaptação marginal em restaurações com sistemas adesivos e resina composta após envelhecimento termomecânico. Foram selecionados 48 molares hígidos que foram restaurados em uma cavidade tipo classe I pela técnica incremental com sistema adesivo convencional de três passos (Adper Scotchbond Multiuso - 3M ESPE) e sistema autocondicionante de dois passos (Clearfill SE bond - Kuraray). Para o sistema adesivo convencional foi realizado o condicionamento ácido total e para o sistema adesivo autocondicionante, o condicionamento ácido foi seletivo no ângulo cavosuperficial em esmalte. Em seguida, os dentes foram alocados aleatoriamente em 6 grupos resultantes da interação da aplicação de uma quantidade padronizada de 1, 2 ou 3 gotas de primer e sistema adesivo. Todos os dentes foram restaurados com a resina composta microhíbrida Charisma (Heraeus Kulzer). Após o polimento das restaurações, estas foram moldadas com polivinilsiloxano e as réplicas foram obtidas em resina epóxica. Em seguida, os espécimes foram levados à máquina de ciclagem termomecânica ERIOS 37000 (ERIOS, São Paulo, Brasil), na qual realizou-se o envelhecimento artificial da restauração através de 200.000 ciclos com carga de 86 N a uma frequência de 2 Hz associados a ciclos térmicos com a temperatura variando entre 5ºC, 37ºC e 55ºC, a cada 30 segundos. Terminado o envelhecimento, obteve-se novas réplicas que foram levadas ao microscópio eletrônico de varredura (MEV) para análise de fendas em comparação com as imagens iniciais. Em seguida os dentes foram submetidos ao ensaio mecânico de resistência de união à microtração por meio de palitos obtidos da interface vestibular, e, posteriormente, avaliou-se o padrão de fratura usando MEV. Para análise de nanoinfiltração, oito palitos de cada grupo foram separados, aleatoriamente, para se avaliar a infiltração de íons de nitrato de prata em MEV. Após o teste termomecânico, os dados foram submetidos à Análise de Variância dois fatores e teste de Tukey com ?= 0,05. Quando o excesso de primer na camada adesiva foi avaliado, o sistema adesivo convencional de três passos apresentou melhores resultados de resistência à união quando comparado ao sistema adesivo autocondicionante de dois passos (?= 0,0015). A quantidade de gotas influenciou a resistência de união à microtração (?= 0,0057). A nanoinfiltração foi maior quando se utilizou maior quantidade de primer e o envelhecimento termomecânico aumentou a formação de fendas marginais. O uso de primer em excesso não é recomendado pois reduz a resistência de união à microtração e forma uma camada híbrida de baixa qualidade / Abstract: This study aimed to evaluate the effects of the amount of primer used in the tooth substrate hybridization on the microtensile bond strength (?TBs), nanoleakage and marginal sealing in dental restorations with adhesive systems and composite resin after thermomechanical aging. A total of 48 human molars were restored class I cavities with incremental technique with a three-step etchand- rinse adhesive system (Adper Scotchbond Multipurpose, 3M ESPE) and twostep self-etching adhesive system (Clearfill SE Bond, Kuraray), For three-step etch-and-rinse adhesive system used total acid etching and for the two-step selfetching system adhesive only enamel cavosurface was acid etching. Then, the teeth were aleatory alocated in 6 groups resulted the interaction between the factors application of standard quantity of primer (1, 2 or 3 drops) and adhesive systems. Afterward a standardized amount of each primer was applied (1, 2, or 3 drops of primer). All teeth were restored with microhybrid composite resin (Charisma, Heraeus Kulzer). After polishing of restorations, they were molded with polyvinylsiloxane and replicas were obtained with epoxy resin. Then the specimens were taken to thermomechanical cycling machine (model 37000 ERIOS), which carried out the artificial aging of restoration through 200,000 cycles with 86 N load at a frequency of 2 Hz associated with thermal cycling and temperature ranging from 5, 37and 55°C every 30 seconds. After aging, new replicas were obtained and images were taken by scanning electron microscope (SEM) to analyze gaps. These images were compared to the initial ones. Then the teeth were subjected to ?TBs testing through beams obtained from buccal interface, and fracture pattern was evaluated using SEM. For nanoleakage analysis, eight beams of each group were randomly separated to assess infiltration with silver nitrate ions and subsequently evaluated by SEM. After the mechanical test, the data were subjected to statistical analysis using two-way Analysis of Variance and Tukey's test (? = 0.05). When primer excess was evaluated at the adhesive layer, the three-step etch-and-rinse adhesive system showed higher bond strength results x when compared to two-step self-etching adhesive system (? = 0.0015). The primer excess influenced ?TBS (? = 0.0057). Nanoleakage was higher when using larger amount of primer was used. Thermomechanical aging increased the formation of marginal gaps. The use of primer in excess is not recommended, because the excess reduces the ?TBs and creates an unsatisfactory hybrid layer on tooth substrate / Mestrado / Dentística / Mestra em Clínica Odontológica

This thesis documents a study of bonding stress and the reliability of GaAs-based lasers for high-power applications. GaAs-based lasers were bonded to oxygen-free high- conductivity (OFHC) copper heat sinks using a eutectic PbSn solder or a silver-filled conductive epoxy, and life tested. Epoxy-bonded devices were observed to have a larger failure rate on life test than solder-bonded devices. Bonding stress, as measured by the degree of polarization (DOP) of photoluminescence, was found to be the largest in epoxybonded devices. As well, the type of heat sink and bonding adhesive affected the stress in the laser material, with bonding stress increasing when there was a larger mismatch of coefficients of thermal expansion between the laser material, adhesive and heat sink. The reliability of the lasers was affected by the amount of force applied to unbonded laser chips. As the applied force increased on a chip centred on a groove, the rate of degradation in the output power increased. A limit in stress tolerance was observed in the lasers, which meant that larger amounts of stress would lead to increased rates of degradation in the output power. As well, the performance of lasers selected from a batch showing poor reliability degraded at an accelerated rate after several hours of operation under applied strain. / Thesis / Master of Engineering (ME)