Thesis (M.S.)--University of Michigan, 1966.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2008. / Directed by Rick Bunch; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Sep. 3, 2009). Includes bibliographical references (p. 48-53).

Thesis (Ph.D)--Materials Science and Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Barbara Boyan; Committee Member: Andres Garcia; Committee Member: Anthony Norman; Committee Member: Nael McCarty; Committee Member: Zvi Schwartz. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2006. / Includes bibliographical references (p. 43-46).

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007. / Dr. J. David Frost, Committee Chair ; Dr. G. Wayne Clough, Committee Co-Chair ; Dr. William F. Marcuson III, Committee Member ; Dr. Paul W. Mayne, Committee Member ; Dr. Susan Burns, Committee Member.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Electrical engineers have responded to the increasing demand for circuit speed and functionality by reducing transistor feature size and increasing on-chip transistor density. Consequently, interconnect density, both on-chip and the system level is also increasing. Increasing circuit speed translates into shorter clock cycles and signals with faster edge rates, which have multi-GHz bandwidth. Densely packed parallel interconnects will cause signal integrity problems not only due to the increase in crosstalk noise but also due to the intrinsic low pass filter characteristics of the interconnects. The lossy nature of the interconnects is also going to increase due to metal surface roughness at higher frequencies, which will further degrade the signal quality at the receiver input. Embedded Patterned Layer (EPL), which is a patterned floating metal layer between a signal trace and its return path shows promise in reducing far-end crosstalk (FEXT). EPL also allows designers to modify the characteristic impedance of interconnects by varying the different physical parameters of the EPL. This dissertation analyzes the effect of EPL on conductor backed coplanar waveguides (CB-CPW). CB-CPWs excite higher order modes at high frequencies, so work was done to understand the effect of different ground via fence parameters in suppressing the higher modes which helps increase the interconnect bandwidth. A CB-CPW with ground via fence is called a grounded coplanar waveguide (GCPW). A very basic lumped element model transmission line model was developed to account for the effect of floating metals near a transmission line. This model was then used to explain the effect of EPL on a GCPW with large bandwidth. EPL reduces the characteristic impedance of the transmission line. Engineers can then design narrow high impedance transmission lines and use EPL to reduce the impedance to a desired value. This also allows reduction in crosstalk by increasing the spacing between the transmission lines. The EPL also reduced the differential impedance of a grounded conductor backed edge coupled coplanar waveguide, when it was used for differential signaling. Care must be taken to make sure that the EPL is symmetric to both the legs of the differential pair to avoid differential to common mode energy conversion, which can cause electromagnetic interference (EMI) problems. EPL reduced FEXT while increasing near-end crosstalk (NEXT), when the coupled transmission line system was used for single ended signaling. Finally, a statistical method for modeling transmission line metal surface roughness in three dimensional (3D) full wave electromagnetic solvers was developed to account for increased attenuation in transmission lines, at high frequencies, due to metal surface roughness.

A doença cárie pode ser tratada com tratamento preventivo e ou tratamento restaurador. Para o tratamento preventivo, pode-se lançar mão da utilização do flúor, sendo sua utilização bastante difundida na Odontologia como eficaz método de promoção de saúde bucal. Já para o tratamento restaurador, utilizam-se materiais restauradores, sendo os compósitos odontológicos umas das principais escolhas entre os materiais restauradores estéticos usados na Odontologia. O objetivo deste estudo foi avaliar a ação de soluções fluoretadas na estabilidade de cor, rugosidade de superfície e análise qualitativa por microscopia eletrônica por varredura de compósitos odontológicos. Após confecção e polimento, os corpos de prova foram imersos em água destilada (controle), flúor fosfato acidulado (1,23%), gel fluoretado neutro (2%) e solução de flúor para bochechos diário (0,05%) por períodos de simulação correspondentes a 1 a 5 anos de uso clínico da solução fluoretada. Foram realizadas leituras de cor (&Delta;E), rugosidade de superfície (Ra) e microscopia eletrônica de varredura previamente e posteriormente a cada ano de ciclagem com as soluções fluoretadas estudadas. Após análise estatística (3-way ANOVA com medidas repetidas Bonferroni nível de significância em p<0.05), observou-se que todos os compósitos estudados apresentaram discreta alteração de cor, dentro do limite clinicamente aceitável (&Delta;E<3,3), sendo crescente de acordo com os anos de simulação clínica de 1 até 5 anos. Quanto à rugosidade, observou-se um padrão de comportamento não homogêneo, sendo, após 5 anos de simulação de uso clínico das soluções fluoretadas, menor que a rugosidade de superfície necessária para causar um aumento da retenção de biofilme dentário (Ra>0,2 &mu;m) para todos os compósitos analisados. A análise das fotomicrografias demonstrou o aparecimento de pequenas depressões na superfície das amostras e penetração de água (solvente) no interior dos compósitos diretos. Conclui-se que a alteração de cor dos compósitos foi clinicamente aceitável e a alteração de rugosidade de superfície não é clinicamente significante após imersão em todas as soluções fluoretadas e tempos estudados. / Dental caries can be treated with preventive treatment or restorative treatment. For preventive treatment, we can resort to the use of fluoride, and its widespread use in Dentistry as an effective method of promoting oral health. As for the restorative treatment, are used restorative materials, dental composites are one of the first choices among the materials used in aesthetic restorative dentistry. The aim of this study was to evaluate the effect of fluoride solution in color stability, surface roughness and qualitative analysis by scanning electron microscopy of dental composites. After preparation and polishing, the specimens were immersed in distilled water (control), acidulated phosphate fluoride (1.23%), neutral sodium fluoride gel (2%) and fluoride mouthwashes for daily (0.05%) for periods simulation corresponding to 1 to 5 years of clinical use of fluoride solution. Readings were taken in color (&Delta;E), surface roughness (Ra) and scanning electron microscopy before and after each year of cycling with the fluoride solution studied. After statistical analysis (3-way repeated measures ANOVA - Bonferroni - a significance level of p<0.05), was observed that all the composites studied showed a slight color change, within clinically acceptable (&Delta;E<3.3), being increased according to the years of clinical simulation from 1 to 5 years. As for the roughness, there was a pattern of behavior is not homogeneous, and, after five years of simulated clinical use of fluoride solution, smaller than the surface roughness required to cause an increased retention of dental plaque (Ra>0.2 &mu;m) for all composites analyzed. The analysis of the photomicrographs showed the appearance of small depressions on the surface and penetration of water (solvent) within the direct composites. We conclude that the color change of the composites was clinically acceptable and the surface roughness change is not clinically significant after immersion in all fluoride solution and times studied.

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-11Bitstream added on 2014-06-13T20:37:54Z : No. of bitstreams: 1 pereira_pc_me_sjc.pdf: 1955962 bytes, checksum: 199a3b76eadceaedbf2923a8f9d4c65f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi avaliar o efeito da vitrificação e do polimento na rugosidade superficial e formação in situ de biofilme dentário inicial, após simulação da escovação, em cerâmica policristalina de zircônia parcialmente estabilizada por ítrio (Cercon® Zirconia, Dentsply Ceramco). Amostras foram divididas em: (C) controle – sem tratamento; (V) vitrificadas; (PS) polidas com pontas de silicone diamantadas. Metade das amostras foi submetida à simulação de escovação (400.000 ciclos). Análises da rugosidade superficial (Ra e Rz) foram realizadas antes e após os tratamentos superficiais e escovação. Dez voluntários selecionados com adequado padrão de higiene bucal receberam dispositivos oclusais individualizados para a fixação das amostras na face vestibular. Após 8 horas em ambiente bucal, as amostras foram removidas do dispositivo e avaliadas em MEV (n=5) e MCVL (n=10). A análise em MEV foi realizada por meio da seleção aleatória de cinco campos (20 x 25 μm) para cada amostra para análise descritiva do material celular/acelular depositado e da topografia superficial. Para análise em MCVL, foram captadas imagens em lentes ópticas com aumento de 10 x/ 0.3 para visualização de toda a amostra e aumento de 63 x/ 0.3 (imagens 3D com secções ópticas de 0,8 μm) para análise de biovolume e espessura média de biofilme. O software COMSTAT quantificou as imagens obtidas em MCVL. Os dados obtidos de rugosidade (μm) foram submetidos à Análise de Variância (dois fatores) e teste de Dunnett (5%). Biovolume e espessura de biofilme foram analisados pelo teste de Kruskal-Wallis e Mann-Whitney. O grupo V apresentou maiores valores de rugosidade superficial, espessura média e biovolume de biofilme, em presença de escovação simulada. O fator escovação não foi preponderante para o aumento da rugosidade superficial. Houve correlação significativa entre... / The aim of this study was to evaluate the effect of the glaze and polishing in the surface roughness and early dental biofilm formation, after toothbrushing simulation, in tetragonal zirconium polycrystal stabilized with yttrium ceramics (Cercon® Zirconia, Dentsply Ceramco). Ceramics samples were divided in three groups: control - not glazed (C); glazed (G); polishing with diamonds silica tip (ST). Half samples was submitted to toothbrushing simulation (400.000 cycles). Analyses of surface roughness (Ra and Rz) were carried before and after the superficial treatments and toothbrushing. Ten volunteers selected with high level of oral hygiene were selected for this study. Oral devices covering the crowns of the upper premolars and molars were fabricated for each participant and ceramic samples were fixed on the vestibular zones of the devices. After 8 hours in situ, the samples were removed from device and analyzed in SEM (n=5) and CLSM (n=10). To SEM analysis was selected means of the random election of five fields (20 x 25 μm) for each sample for descriptive analysis of the deposited cellular material/to acelular and the superficial topography. For analysis in CLSM were used for architecture visualization and lenses of 63x/0.13 for COMSTAT analysis and quantification. The resulting sets of confocal optical sections were collected by microscopy software as stacks of images 3-D images were obtained for analysis of biovolume and average thickness of biofilm. The data of surface roughness (μm) were submitted to analysis of variance (two factors) and Dunnett’s test (5%). Biovolume and mean thickness biofilm were analyzed by Kruskal-Wallis and Mann-Whitney’s test. The G Group presented greaters values of surface roughness, average thickness and biovolume of biofilm, in toothbrushing presence... (Complete abstract click electronic access below)