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The study of nanomaterials is a developing science with potentially large benefits in the development of catalysts, optical and chemical sensors, and solid state memory devices. As several of these devices require large arrays of nanoparticles, one of the greatest obstacles in material characterization and device development is the reliable manufacture of nanopatterns over a large surface area. In addition, various applications require different nanoparticle size and density. High density arrays with small nanoparticle sizes are difficult to achieve over a large surface area using current manufacturing processes. Herein, Nanoimprint Lithography (NIL) and Dynamic Templating are combined to create a new manufacturing process capable of developing high density arrays with small nanoparticle sizes. The NIL process involves the stamping of a polymer coated substrate by a silicon stamp with patterned nanofeatures. The stamp is then removed, leaving the pattern in the polymer, which is first etched and then coated with a thin layer of metal, filling the recessed regions of the pattern. The excess polymer is dissolved, leaving a pattern of nanoparticles on the substrate matching the pattern on the stamp. When Dynamic Templating is applied, a very thin layer of metal can be coated, which forms small nanoparticle sizes when dewetted. A custom NIL system has been developed to combine these two processes together, which has now proven to yield consistent large-area, dense arrays with a small nanoparticle size. An array spacing of 700 nm has been achieved, along with a nanoparticle size of 90 nm. Arrays have been created in gold and palladium, where there is now the potential to combine them with other solution-based syntheses which should lead to complex nanoparticle geometries suitable for sensor applications. / Mechanical Engineering

Made available in DSpace on 2016-01-26T12:51:22Z (GMT). No. of bitstreams: 1 fabiostuchidevito_tese.pdf: 1050230 bytes, checksum: 52d8e95acef4a4ba2f5e60d301266786 (MD5) Previous issue date: 2009-04-17 / Total hip arthroplasty is a surgery with a high success rate, providing pain relief and improvement of the articular mobility. Long-term success is related to the position and orientation of the acetabular and femoral components. Traditional preoperative planning entails radiographic analysis of the pelvis, in which a template is placed on the image, allowing an analysis of the appropriate size of the Exeter cemented prosthesis. Objective: To evaluate the effectiveness of traditional preoperative planning with the use of templating. Patients and Method: Forty-three anteroposterior X-rays were analyzed by three experienced surgeons. The evaluation of each surgeon was compared with the actual prosthesis used in the surgery and also compared with the assessment of the other two surgeons. Cohen's Kappa concordance test and weighted Kappa indexes using quadratic weighting were used for statistical analysis with a confidence interval of 95%. Results: The preoperative evaluations of Surgeons A, B and C were divided into the analysis of the sizes of the acetabular cup, stem and plug of the distal femoral canal. Surgeon A obtained a moderate agreement in relation to the acetabular component and substantial agreements in relation to the stem and plug. Surgeon B had moderate agreement in relation to both the acetabulum and the stem and substantial agreement in relation to the plug. Surgeon C obtained moderate agreement in relation to the analysis of the acetabulum and the plug and substantial agreement for the stem. The intra-observer agreement test demonstrated a prevalence of slight agreement in relation to the acetabulum and substantial agreement in relation to the stem and to the plug. Conclusion: Templating used in preoperative planning proved effective; however, there was a prevalence of slight and moderate agreement in relation to the size of the acetabular component according to the inter- and intra-observer analysis. / A artroplastia total do quadril é uma cirurgia com alto índice de sucesso, atuando no alívio da dor e melhora da mobilidade articular e seu êxito a longo prazo relaciona-se à posição e orientação do componente acetabular e femoral. O planejamento pré-operatório tradicional consiste na análise radiográfica da bacia, na qual será sobreposto um templating , o que permite a análise do tamanho adequado da prótese Exeter cimentada. Objetivo: Avaliar a eficácia do planejamento pré-operatório tradicional pelo uso do templating . Casuística e Método: Quarenta e três radiografias na posição antero-posterior e foram analisadas por três cirurgiões experientes; as avaliações de cada cirurgião foram comparadas com a prótese utilizada na cirurgia e cada resultado comparado com os resultados dos outros dois. Para avaliação, utilizou-se o teste de concordância do Capa de Cohen e do Capa ponderado, com ponderação quadrática e intervalo de confiança de 95%.Resultados: Os resultados pré-operatório encontrados pelo examinadores A, B e C foram divididos como análise do tamanho do acetábulo, haste e plug do canal femoral distal. O cirurgião A obteve em relação ao componente acetabular uma concordância moderada, e em relação à haste e ao plug uma concordância substancial. O cirurgião B apresentou resultado de concordância moderada em relação ao acetábulo e à haste e substancial em relação ao plug. O cirurgião C na análise acetabular e do plug obteve concordância moderada e substancial quanto à haste. O teste de concordância intra-observador apresentou uma prevalência da concordância leve em relação ao acetábulo e substancial em relação à haste e ao plug. Conclusão: O templating utilizado no planejamento pré-operatório mostrou-se eficaz, no entanto, em relação ao tamanho do componente acetabular houve um predomínio de concordância leve e moderada na análise inter e intraobservador.

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La mise en forme par ice-templating est un procédé d'élaboration permettant via la congélation d'une suspension, d'obtenir des matériaux poreux à porosité contrôlée. L'analyse des mécanismes régissant la congélation de suspensions concentrées en particules et leurs conséquences sur les microstructures poreuses, est très peu développée dans la littérature du point de vue de l'influence de la composition de la suspension, en termes de nature et quantité d'additifs. Les objectifs de ces travaux de thèse sont d'observer et caractériser in situ et ex situ la formation des structures par ice-templating. Il s'agit également d'établir les liens entre la composition des suspensions, le procédé et la morphologie poreuse obtenue pour les structures congelées et frittées qui en découlent. L'évolution de l'avancée du front de congélation d'un panel de suspensions d'alumine aux propriétés caractérisées a été observée par radiographie X et la microstructure des échantillons congelés et frittés a été caractérisée par tomographie X ou par MEB. Nous avons ainsi pu caractériser les différentes étapes de la congélation par ice templating, les microstructures congelées associées, l'influence de la composition de la suspension ainsi que les mécanismes générateurs de défauts. La force ionique générée par la quantité de dispersant, la présence ou non de liant et la vitesse de refroidissement des suspensions sont trois paramètres ayant des conséquences critiques sur la microstructure et sur l'orientation ou la désorientation des cristaux. Nos résultats apportent un éclairage inédit sur les mécanismes de congélation des sols étudiés en géophysique et notamment la formation de glace lenticulaire.

Hip resurfacing is an alternative to total hip arthroplasty for the young and active patient likely to outlive traditional means of hip joint replacement. The acetabular cup is implanted in much the same fashion as an uncemented total hip arthroplasty, however, implantation of the femoral component is unique to hip resurfacing, presenting both distinct benefits and limitations. Hip resurfacing spares much of the proximal femur including the femoral neck and portions of the femoral head. This may be advantageous if the patient requires revision surgery; however, preservation of the femoral neck bears with it the risk of femoral neck fracture. The exact mechanism of neck fracture is not fully understood. Avoiding potential fracture risks is vital to ensuring optimal patient outcomes. The current work investigated mechanical femoral head preparatory factors that may predispose to femoral neck fracture. Intra-operative computer navigation is emerging as the gold-standard in orthopaedic care. In hip resurfacing, navigation may improve the surgeon’s ability to optimally implant the resurfacing prosthesis; however, much of this technology is still in its infancy and requires investigation into the accuracy and repeatability of this peri-operative tool. Pre-operative planning can assist the surgeon in optimally determining the size and position of the resurfacing components, specifically in reference to the patient’s unique anatomy, prior to performing the operation. This may aid in correct implant selection and provide a basis on which to conduct intra-operative navigation. However, the accuracy and repeatability of pre-operative planning for hip resurfacing has not yet been established. Thus, this body of work looked to establish a clear methodology for pre-operative planning, intra-operative computer navigation and surgical technique in order to optimize preparation of the femoral head, ultimately reducing the risk of femoral neck fracture in hip resurfacing.

Hip resurfacing is an alternative to total hip arthroplasty for the young and active patient likely to outlive traditional means of hip joint replacement. The acetabular cup is implanted in much the same fashion as an uncemented total hip arthroplasty, however, implantation of the femoral component is unique to hip resurfacing, presenting both distinct benefits and limitations. Hip resurfacing spares much of the proximal femur including the femoral neck and portions of the femoral head. This may be advantageous if the patient requires revision surgery; however, preservation of the femoral neck bears with it the risk of femoral neck fracture. The exact mechanism of neck fracture is not fully understood. Avoiding potential fracture risks is vital to ensuring optimal patient outcomes. The current work investigated mechanical femoral head preparatory factors that may predispose to femoral neck fracture. Intra-operative computer navigation is emerging as the gold-standard in orthopaedic care. In hip resurfacing, navigation may improve the surgeon’s ability to optimally implant the resurfacing prosthesis; however, much of this technology is still in its infancy and requires investigation into the accuracy and repeatability of this peri-operative tool. Pre-operative planning can assist the surgeon in optimally determining the size and position of the resurfacing components, specifically in reference to the patient’s unique anatomy, prior to performing the operation. This may aid in correct implant selection and provide a basis on which to conduct intra-operative navigation. However, the accuracy and repeatability of pre-operative planning for hip resurfacing has not yet been established. Thus, this body of work looked to establish a clear methodology for pre-operative planning, intra-operative computer navigation and surgical technique in order to optimize preparation of the femoral head, ultimately reducing the risk of femoral neck fracture in hip resurfacing.

Nanoemulsions are templates that have the potential to fill the gap between micellar systems and latex particles in the preparation of porous materials. A nanoemulsion can also be used as a carrier for uploading the desired materials inside the pore formed after the removal of the template. In this research, oil-in-water (O/W) nanoemulsions were prepared by means of a low-energy method based on a phase inversion composition (PIC) technique, using two nonionic surfactants (Tween 80 and Span 80), which can be mixed in order to adjust the hydrophilic-lipophilic balance (HLB). The influence of a number of parameters on the tunability and stability of such nanoemulsions was also studied. The effect of the simultaneous intercrossing of multifactors on droplet size was explored using a process- mixture design, and the size of the nanoemulsion oil droplets was measured by means of dynamic light scattering (DLS). The nanoemulsions were combined with sol-gel method in order to prepare porous silica with a macroporosity in the 50 nm to 400 nm range. The results demonstrate that a precise synergy between the silica source and the nanoemulsions is essential for effective interactions and homogeneous structures. Depending on the nature of such interactions, a variety of materials were observed, from hollow particles to continuous gels. Changing the size of the oil droplet and the volume of the nanoemulsions produced silica with differing pore sizes and varying total pore volumes. The obtained hierarchical porous silica (HPS) were characterized using mercury porosimetry, small angle X-ray scattering (SAXS), nitrogen isotherms, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The parallel use of the oil vesicles as containers for the further synthesis of metal oxide is a novel method of internally functionalizing the silica. When hydrophobic metal precursors are dissolved into the oil phase before the preparation of the nanoemulsion, they are confined within the globular cavities of the silica. The thermal treatment applied to the material to burn the organics then leads to the final formation of metal oxide nanoparticles, which are larger than the porosity of the silica matrix but entrapped within the large cavities, producing a "rattle-like" structure. This method was demonstrated through the synthesis of Fe2O3, Fe3O4, and Co3O4 nanoparticles, and the results showed that a rather large amount of metal oxide (up to a 60 wt.% of metal oxide in nanocomposites) be generated while still maintaining the nanometric size observed at lower concentrations. This method allows control of the type of metal oxide, the concentration of the metal oxide, and the pore size, which enables the creation of different types of nanocomposites. Metal oxide hierarchical porous silica (MHPS) nanocomposites were characterized based on nitrogen isotherms, TEM and SEM observations, FTIR analysis, X-ray diffraction (XRD), and Mossbauer spectroscopy. Magnetic measurements were also taken. This new method, using the new templating objects, is a perfect illustration of the concept of "integrative synthesis,??? whereby the combination of building units and reactional mechanisms leads to complex structures as a result of true synergy among the elements during the reaction. In this case, the size of the nanoemulsion and the total water volume both contribute to the generation of distinctive architectures. In addition, the reaction of the metal oxide precursors within the cavities limits the extension of the final crystal size, but the surrounding solid matrix plays a role as well by keeping the particles apart. The final factor is that the reactive materials cannot leak from the silica because of the rattle-like structure, but the reagents can reach those particles through the porosity of the silica framework.