Orientador: Paulo Henrique dos Santos / Resumo: Objetivo: O objetivo do estudo foi avaliar o efeito da aplicação de ácido fluorídrico com diferentes tempos e concentrações na superfície de materiais restauradores indiretos obtidos a partir de blocos utilizados na tecnologia CAD-CAM. Materiais e Métodos: Amostras dos materiais restauradores indiretos medindo 4x4x0,8mm foram obtidos a partir de blocos CAD para cada material estudado: resina nanocerâmica Lava Ultimate (3M Espe), monossilicato de lítio reforçado por zircônia Celtra Duo (Dentsply) e cerâmica híbrida Vita Enamic (Vita). Os materiais foram submetidos à aplicação de ácido fluorídrico com concentração de 5% ou 10%, sendo o mesmo aplicado pelos tempos de 20, 40, 60 ou 90 segundos. Um grupo controle para cada material foi avaliado, sem nenhum tratamento de superfície, contabilizando nove grupos de cada material (n=10). As amostras foram avaliadas em relação à rugosidade de superfície (Ra e Rz), avaliadas em microscopia óptica confocal; ângulo de contato (θ), energia de superfície (s) e energia livre total de interação (∆G) avaliados em goniômetro, e resistência de união ao cimento resinoso avaliada através do teste de microcisalhamento. Imagens das amostras foram obtidas em microscopia eletrônica de varredura (MEV), microscopia óptica confocal e microscopia de força atômica. Os dados de rugosidade de superfície, ângulo de contato, energia de superfície, energia livre total de interação e resistência de união foram submetidos à ANOVA dois fatores e teste de Tukey (p<... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Purpose: The aim of this study was to evaluate the effect of different times and concentration of hydrofluoric acid etching on the surface of indirect restorative materials obtained from blocks used in CAD-CAM technology. Methods and Materials: Samples of indirect restorative materials measuring 4x4x0.8mm were obtained for each restorative material studied: Lava Ultimate nanoceramic resin (3M Espe), Celtra Duo zirconia-reinforced lithium silicate ceramic (Dentsply) and Vita Enamic polymer-infiltrated ceramic-network material (Vita). The materials were submitted to etching with 5% or 10% hydrofluoric acid for 20, 40, 60 or 90 seconds. A control group for each material was evaluated without any surface treatment, totaling nine experimental groups for each material (n = 10). The samples were evaluated in relation to surface roughness (Ra and Rz), evaluated by confocal optical microscopy; contact angle (θ), surface energy (s) and total free interaction energy (∆G) evaluated by goniometer; and microshear bond strength to resin cement. Sample images were obtained by scanning electron microscopy (SEM), confocal optical microscopy and atomic force microscopy. Data of surface roughness, contact angle, surface energy, total free interaction energy and bond strength were submitted to two-way ANOVA and Tukey test (p<0.05). Results: The results showed that, in general, the Celtra Duo zirconia-reinforced lithium silicate ceramic showed better results when subjected to etching with 10% hyd... (Complete abstract click electronic access below) / Mestre

This thesis is to study the microstructure and its related surface properties of CrxNy¡BDLC and TiO2 films prepared by different plasma energy processes such as physical vapor deposition (PVD) and plasma immersion ion implantation (PIII) processes. In the first chapter of this thesis, the different Cr-based coatings (Cr, Cr2N and CrN) were prepared by PVD process with lower plasma energy condition (less than 100 eV). The surface energy properties of these Cr-based coating were studied and the relationship between the surface properties and adhesion forces with respect to epoxy molding compound (EMC) were also investigated. It is found that the PVD-Cr2N coating has the largest contact angle of water and the lowest polar components and surface energy. The low surface energy is attributed to the high density of surface reactive sites and the formation of N-H bonds and O-H bonds on the film surface that act as the effective adsorption sites for carbon. The second chapter focuses on the modification of the electrical and mechanical properties of DLC films with high plasma energy (5¡ã45 keV) , PIII post-treatment. It is found that using high ion energy and a short treating time can modify the sp3 content, the nano-hardness and the Young¡¦s modulus of the DLC films. The formation mechanisms of sp3 C-C bonds in the implanted DLC film involve the reaction among compressive stress field, bonds breakage and recombination process induced by hydrogen and carbon ion. The third chapter deals with the structure and photocatalytic properties of nitrogen-doped TiO2 film prepared by PVD process with lower plasma energy condition (less than 100 eV). The TiO2-xNx films are indirect transition type and optical band gap energy is various with increasing nitrogen flow rate. The TiO2-xNx film with high crystallinity and porous surface morphology shows the best degradation rate of methylene blue solution.

Blood contacting devices are frequently limited by complications such as surface-induced thrombosis. This thesis investigated the feasibility of using a family of recombinant elastin-like polypeptides (ELPs), namely ELP1, ELP2 and ELP4 that differ by molecular weight and sequence length, as potential thromboresistant coatings. The ELP coatings were prepared by physical adsorption onto the surface of Mylar, with surface modification confirmed by goniometry, X-ray photoelectron spectroscopy (XPS), and chemical force microscopy (CFM). Both surface wettability and hydrophilic adhesion force increased as the ELP sequence length decreased. The ELP adsorption process monitored by using quartz crystal microbalance with dissipation (QCM-D) showed that the ELPs adsorbed within a monolayer. Additionally, ELP surface coverage was found to increase with the polypeptide sequence length. The QCM-D studies also revealed that the longer polypeptides (ELP2 and ELP4) exhibited higher specific dissipation values indicating that they established adsorbed layers with greater structural flexibility and associated water content compared to ELP1. Exposure of the ELP coatings to flowing reconstituted blood demonstrated that both the ELP2 and ELP4 coatings reduced the quantity of adsorbed fibrinogen (Fg), with the ELP4 coating resulting in the lowest levels of adherent platelets. Energy dissipation versus frequency shift plots obtained from QCM-D studies indicated that adsorbed Fg on the ELP4 coating maintained a softer, more flexible film then on the other ELPs. The ELP4 coating also demonstrated an altered binding activity for GPIIb/IIIa where only the AGDV motif in the adsorbed Fg gamma-chain appeared to be exposed and bioactive. Conversely, on the other ELP coatings both the AGDV and RGD motifs (found within the Fg alpha-chain) were available for binding, suggesting that a different Fg conformational state exists on the ELP1 and ELP2 coatings. Moreover, both the ELP2 and ELP4 coatings displayed minimal bulk platelet reactivity following extended whole blood shear exposure (up to an hour) compared to Mylar. This was not observed with the ELP1 coating. Overall, the results suggest that the structural flexibility and associated water content of the ELP coatings appear to be important criteria influencing their thrombogenicity, with ELP4 displaying the most favourable blood-material response compared to ELP1 and ELP2.

This paper explores the surface properties of skin and eyes and their importance in the acceptance and success of a digital human face, specifically in relation to the uncanny valley. The uncanny valley hypothesis states that as a human representation approaches photo-realism, subtle differences from reality become unsettling. Recent studies suggest that the uncanny valley could exist over a far greater range, affecting abstract human representations as well. These competing findings are explored by analyzing how changes to the surface of a digital character affect its level of acceptance. A female facial model is used as a base to compare a spectrum of different simulated real-world materials. The variations range from materials that are nearly identical to human skin, to those that are completely divergent from it, thus unnatural. After studying this catalogue of materials, it is concluded that given the right conditions, the uncanny valley can occur when facial representations are very near realism, as well as when human-likeness is quite distant from reality.

Blood contacting devices are frequently limited by complications such as surface-induced thrombosis. This thesis investigated the feasibility of using a family of recombinant elastin-like polypeptides (ELPs), namely ELP1, ELP2 and ELP4 that differ by molecular weight and sequence length, as potential thromboresistant coatings. The ELP coatings were prepared by physical adsorption onto the surface of Mylar, with surface modification confirmed by goniometry, X-ray photoelectron spectroscopy (XPS), and chemical force microscopy (CFM). Both surface wettability and hydrophilic adhesion force increased as the ELP sequence length decreased. The ELP adsorption process monitored by using quartz crystal microbalance with dissipation (QCM-D) showed that the ELPs adsorbed within a monolayer. Additionally, ELP surface coverage was found to increase with the polypeptide sequence length. The QCM-D studies also revealed that the longer polypeptides (ELP2 and ELP4) exhibited higher specific dissipation values indicating that they established adsorbed layers with greater structural flexibility and associated water content compared to ELP1. Exposure of the ELP coatings to flowing reconstituted blood demonstrated that both the ELP2 and ELP4 coatings reduced the quantity of adsorbed fibrinogen (Fg), with the ELP4 coating resulting in the lowest levels of adherent platelets. Energy dissipation versus frequency shift plots obtained from QCM-D studies indicated that adsorbed Fg on the ELP4 coating maintained a softer, more flexible film then on the other ELPs. The ELP4 coating also demonstrated an altered binding activity for GPIIb/IIIa where only the AGDV motif in the adsorbed Fg gamma-chain appeared to be exposed and bioactive. Conversely, on the other ELP coatings both the AGDV and RGD motifs (found within the Fg alpha-chain) were available for binding, suggesting that a different Fg conformational state exists on the ELP1 and ELP2 coatings. Moreover, both the ELP2 and ELP4 coatings displayed minimal bulk platelet reactivity following extended whole blood shear exposure (up to an hour) compared to Mylar. This was not observed with the ELP1 coating. Overall, the results suggest that the structural flexibility and associated water content of the ELP coatings appear to be important criteria influencing their thrombogenicity, with ELP4 displaying the most favourable blood-material response compared to ELP1 and ELP2.

There is great interest in the plant Cannabis sativa (hemp) as a source of technical fibres for the reinforcement of polymers in composite materials due to its high mechanical properties. As a natural fibre hemp also offers biodegradabilty and is therefore an inexpensive and renewable alternative to glass fibres However, the environmental benefits of natural fibres cannot be fully exploited if the manufacturing of their composites involves polluting processing steps. Unfortunately, there is still a lack of environmetally sustainable processing methods yielding technical fibres of sufficient quality. Enzyme application as a biotechnological processing method is a good candidate for this aim and is therefore actively investigated at present. In this work the effects of a range of enzymes on the morphological, compositional and mechanical properties of hemp was investigated. The enzymes were firstly characterised and then applied to hemp fibre for differing periods of time. After visual inspection, a set of fibre samples were selected and subjected to further analysis by Fourier-Transform Infrared Spectroscopy (FTIR), tensile testing and scanning electron microscopy (SEM). The commercial formulation Pectinex® Ultra-SL emerged as the most efficient in terms of treatment time and fibre quality. The effectiveness of treatments was further investigated by developing a novel experimental method that correlates the adhesion forces measured by atomic force microscopy (AFM) on the fibre surface to the properties of the fibres or composites. In order to identify correlations between the adhesion forces and fibre or composite properties, hemp fibre was subjected to four distinctly different treatments to obtain significant differences between fibre properties. The fibres and composites were then analyzed using a combination of FTIR, tensile testing, 3-point bend testing, dynamic mechanical analysis (DMA) and SEM. Based on this comprehensive dataset the AFM data was correlated using the software SPSS. The information derived from AFM (adhesion forces and surface topology) was useful in the clarification of fibre modifications evoked by the treatments.

Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Oct. 31, 2007). Includes bibliographical references (p. 99-112).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [210]-223).

Orientador: Elcio Marcantonio Junior / Resumo: O foco principal deste estudo centrou-se sobre as propriedades da superfície do titânio comercialmente puro, Ti6Al4V e novas ligas de TiNbZr, quando empregada técnica de modificação de superfície por anodização anódica com cálcio e fósforo. Foram avaliadas tanto a caracterização topográfica dos metais como sua relevância com interações com estruturas ósseas adjacentes. As técnicas de caracterização de superfície: rugosidade superficial, MEV, MFA e interferometria ótica foram utilizadas para determinar os padrões topográficos específicos para cada uma das amostras utilizada neste estudo e, para análise das interções biológicas, avaliou-se em conjunto a porcentagem de contato ósseo das novas superfícies funcionais in vivo, em coelhos. A anodização promoveu formação de uma multicamada de poros com incorporação de íons cálcio e fósforo nas superfícies do Ti cp e das ligas Ti6Al4V, Ti35Nb5Zr e Ti35Nb10Zr. A liga Ti35Nb10Zr foi considerada moderadamente rugosa (1.061µm ±0.179) e apresentou os melhores paramâmetros de rugosidade, o que pode ter influenciado em maior porcentagem de contato ósseo, quando comparadas aos demais grupos deste estudo. Comprovamos que as ligas Ti35Nb5Zr e Ti35Nb10Zr, em especial a liga Ti35Nb10Zr anodizada, apresentam boas propriedades biológias que permitirão que estes materiais possam ser empregados, em um futuro próximo, na confecção de novos sistemas de implantes. / The focused of this stydy was based on surface properties of commercially pure titanium, Ti6Al4V and new TiNbZr alloys with surface modification technique by anodic anodization with Ca and P. Topographic characterization of metals and biological interactions relevance were evaluated. Surface characterization techniques: surface roughnesses, SEM, AFM, optical interferometry were performed to determine specific topographic patterns for each samples used in this study and additionally, the percentage of bone contact of new functional surfaces was evaluated in vivo by histometry. Anodization technique promoted a multilayer pores with calcium and phosphorus incorporation on the surfaces: cp Ti and Ti6Al4V, Ti35Nb5Zr and Ti35Nb10Zr alloys. Ti35Nb10Zr alloy was considered with moderately rough (1.061µm ±0.179) and showed the best roughness parameters, may trigger suitable biological responses when compared to other groups of this study. It was concluded that Ti35Nb5Zr and Ti35Nb10Zr alloys, especially anodized Ti35Nb10Zr alloy, exhibit biocompatible properties that allow these materials can be used to make new implant systems in a short future. / Doutor

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