This thesis describes the design, fabrication, and testing process for a microfluidic phosphate colorimeter utilized for water quality analysis. The device can be powered by, and interfaced for data collection with, a common cell phone or laptop to dramatically reduce costs. Unlike commercially available colorimeters, this device does not require the user to measure or mix sample and reagent. A disposable poly(dimethylsiloxane) (PDMS) microfluid chip, powered by an absorption pumping mechanism, was used to draw water samples, mix the sample at a specific ratio with a molybdovanadate reagent, and load both fluids into an onboard cuvette for colorimetric analysis. A series of capillary retention valves, channels, and diffusion pumping surfaces passively controls the microfluidic chip so that no user input is required. The microfluidic chip was fabricated using a modified SU-8 soft lithography process to produce a 1.67mm light absorbance pathlength for optimal Beer Lambert Law color absorbance. Preliminary calibration curves for the device produced from standard phosphate solutions indicate a range of detection between 5 to 30mg/L for reactive orthophosphate with a linearity of R²=91.3% and precision of 2.6ppm. The performance of the PDMS absorption driven pumping process was investigated using flow image analysis and indicates an effective pumping rate up to approximately 7µL/min to load a 36µL sample.

This dissertation shows a detailed investigation on reconfigurable low profile antennas using tunable high impedance surfaces (HIS). The specific class of HIS used in this dissertation is called a frequency selective surface (FSS). This type of periodic structure is fabricated to create artificial magnetic conductors (AMCs) that exhibit properties similar to perfect magnetic conductors (PMCs). The antennas are intended for radiometric sensing applications in the biomedical field. For the particular sensing application of interest in this dissertation, the performance of the antenna sub-system is the most critical aspect of the radiometer design where characteristics such as small size, light weight, conformability, simple integration, adjustment in response to adverse environmental loading, and the ability to block external radio frequency interference to maximize the detection sensitivity are desirable. The antenna designs in this dissertation are based on broadband dipole antennas over a tunable FSS to extend the usable frequency range. The main features of these antennas are the use of an FSS that does not include via connections to ground, their low profile and potentially conformal nature, high front-to-back radiation pattern ratio, and the ability to dynamically adjust the center frequency. The reduction of interlayer wiring on the tunable FSS minimizes the fabrication complexity and facilitates the use of flexible substrates. This dissertation aims to advance the state of the art in low profile tunable planar antennas. It shows a qualitative comparison between antennas backed with different unit cell geometries. It demonstrates the feasibility to use either semiconductor or ferroelectric thin film varactor-based tunable FSS to allow adjustment in the antenna frequency in response to environment loading in the near-field. Additionally, it illustrates how the coupling between antenna and HIS, and the impact of the varactor losses affect the antenna performance and it shows solutions to compensate these adverse effects. Novel hybrid manufacturing approaches to achieve flexibility on electrically thick antennas that could be transitioned to thin-film microelectronics are also presented. The semiconductor and ferroelectric varactor-based tunable low profile antennas demonstrated tunability from 2.2 GHz to 2.65 GHz with instantaneous bandwidths greater than 50 MHz within the tuning range. The antennas had maximum thicknesses of λ/45 at the central frequency and front to back-lobe radiation ratios of approximately 15dB. They also showed impedance match improvement in the presence of a Human Core Model (HCM) phantom at close proximity distances of the order of 10-20 mm. In addition, the use of thin film ferroelectric Barium Strontium Titanate (BST) varactors in the FSS layer enabled an antenna that had smaller size, lower cost and less weight compared to the commercially available options. The challenging problems of fabricating robust flexible antennas are also addressed and novel solutions are proposed. Two different types of flexible antennas were designed and built. A series of flexible microstrip antennas with slotted grounds which demonstrated to be robust and have 42% less mass than typically used technologies (e.g., microstrip antennas fabricated on Rogers® RT6010, RT/duroid® 5880, etc.); and flexible ferroelectric based tunable low profile antennas that showed tunability from 2.42 GHz to 2.66 GHz using overlapping metallic plates instead of a continuous ground plane. The bending test results demonstrated that, by placing cuts on the ground plane or using overlapping metallic layers that resemble fish scales, it was possible to create highly conductive surfaces that were extremely flexible even when attached to other solid materials. These new approaches were used to overcome limitations commonly encountered in the design of antennas that are intended for use on non-flat surfaces. The material presented in this dissertation represents the first investigation of reconfigurable low profile antennas using tunable high impedance surfaces where the desired electromagnetic performance as well as additional relevant features such as robustness, low weight, low cost and low complexity were demonstrated.

Diese Arbeit besteht aus drei Teilen. Im ersten Teil wurde Holz mit verschiedenen, kommerziell erhältlichen Kieselsolen behandelt, die unterschiedliche pH-Werte und Oberflächenmodifikationen aufwiesen. Basische Kieselsole vermochten nicht in das Holz einzudringen, da ihr pH-Wert während des Eindringens absinkt und es zur Ausfällung des Kieselsols im Holz kommt. Neutrale und saure Kieselsole hingegen konnten problemlos in das Holz eingebracht werden. Eines der sauren Kieselsole, welches mittels Aluminumoxychlorid kationisch modifiziert war, reduzierte die Wasseraufnahme und den pilzlichen Abbau durch die Braunfäule Coniophora puteana (Kiefer) und die Weißfäule Trametes versicolor (Buche). Im Bläuetest zeigte sich ein verminderter Befall durch Aureobasidium pullulans, allerdings kein kompletter Schutz gegen diesen Pilz. Auch die kleinsten verfügbaren Partikelgrößen für Kieselsole ergaben keinerlei Zunahme des Zellwandvolumens (chemische Quellung, Bulking), was darauf hinweist, dass eine Eindringung in die Zellwand nicht stattfand. Es erscheint daher nicht möglich, Kieselsole in die Zellwand einzubringen und die Dimensionsstabilität des Holzes zu verbessern. Da Kieselsol lediglich in die Lumen der Holzzellen eingebracht werden kann, kann die Behandlung nicht als wirkliche Holzmodifizierung angesehen werden. Wegen der vielversprechenden Ergebnisse in den Wasseraufnahmeversuchen und den Pilztests wurde mit dem kationischen Kieselsol behandeltes Holz thermogravimetrisch und in einem Brandtest untersucht. Im thermogravimetrischen Test zeigte sich eine leicht verminderte Pyrolysetemperatur (eine übliche Wirkung von Feuerschutzmitteln), die Holzkohlemenge war jedoch nicht erhöht. Dies zeigt, dass die Menge an brennbaren Gasen, die während der Pyrolyse freiwerden, durch das Kieselsol nicht vermindert wurde. Auch zeigte die resultierende Holzkohle gleiche Oxidationseigenschaften wie die Holzkohle der Kontrollen. Im Brandtest wurden die Branddauer, die Brandgeschwindigkeit und der Gewichtsverlust vermindert. Das Nachglühen der Holzkohle wurde komplett unterbunden. Alle diese Effekte waren jedoch relativ klein verglichen mit den Effekten eines kommerziell erhältlichen Feuerschutzsalzes, welches ebenfalls als Referenzbehandlung getestet wurde. Im zweiten Teil der Arbeit wurden acetoxyfunktionelles Silan und verschiedene Polydimethylsiloxane (PDMS) mit Acetanhydrid kombiniert, um Holz zu acetylieren. Die PDMS hatten die folgenden Funktionalitäten: Amino, Acetoxy, Hydroxy und nicht-funktionell. Die beste Hydrophobierung des acetylierten Holzes wurde durch die Kombination mit acetoxyfunktionellem PDMS erreicht, welches anschließend in verschiedenen Konzentrationen getestet wurde. Eine Konzentration von 1% in Acetanhydrid zeigte bereits eine maximale Hydrophobierung, welches darauf schließen lässt, dass die inneren Oberflächen des Holzes mit dem PDMS belegt und hydrophobiert wurden. Die Pilzresistenz des behandelten Holzes wurde durch die Kombination mit dem PDMS nicht beeinflusst. Bei Wasserlagerung zeigte sich eine leichte Überquellung des Holzes, welches mit der Kombination von Acetanhydrid und PDMS acetyliert worden war. Untersuchungen der Biegefestigkeit und Bruchschlagarbeit ergaben jedoch keinen Einfluss. Im dritten Teil der Arbeit wurden wasserbasierte Emulsionen von funktionellen PDMS zur Imprägnierung von Holz eingesetzt. Es wurde untersucht, ob Resistenz gegen pilzlichen Abbau und Hydrophobierung wie auch erhöhte Dimensionsstabilität mit dieser Behandlung erreicht werden kann. Die α-ω-gebundenen Funktionalitäten der PDMS waren: Amino, Carboxy, Epoxy und Carbobetain. Die stärkste Hydrophobierung wurde mit dem carbobetain-funktionellen PDMS erreicht, allerdings ergab diese Behandlung keine verbesserte Pilzresistenz gegenüber einem Abbau durch Coniophora puteana und Trametes versicolor. In dieser Hinsicht die beste Wirkung zeigte die Behandlung mit carboxy-funktionellem PDMS. Dieses Material verminderte jedoch die Wasseraufnahmerate nur ungenügend und wurde außerdem stark ausgewaschen. Daher wurden in der Folge amino-funktionelles und carboxy-funktionelles PDMS kombiniert, um durch eine Salzbildung der beiden Funktionalitäten eine verbesserte Fixierung des carboxy-funktionellen Siloxans zu erreichen. Die Kombination zeigte bei einem Überschuss an amino-funktionellem PDMS eine gute Fixierung, jedoch ansonsten keine Synergieeffekte. Die Dimensionsstabilität des Holzes wurde durch die Behandlungen nur sehr geringfügig verbessert. Hierfür müsste eine gute Eindringung der Chemikalien in die Zellwand erfolgen und ein dauerhaftes Bulking erzielt werden. Die Eindringung der Chemikalien in die Zellwand war jedoch in allen Fällen nur gering.

Orientador: Prof. Dr. Reynaldo Palácios Bereche / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2015. / No presente trabalho foi desenvolvida uma análise de desempenho da inserção da tecnologia de membranas, visando a potencialização da produção de etanol, e o impacto desta sobre a destilação convencional para a separação do etanol até o grau de etanol hidratado combustível (EHC). A pervaporação com membranas de PDMS (polidimetilsiloxano) foi adotada como alternativa tecnológica para a intensificação da fermentação alcoólica, a partir de sacarose em forma de melaço de cana. Três arranjos de operação de fermentação foram selecionados e avaliados como alternativa à intensificação da operação, a fermentação em batelada com fermentadores SBF (Simple Batch Fermenter) representa o regime transitório, para o regime estacionário foi selecionado um fermentador contínuo, CSTF (Continuous Stirred Tank Fermenter). Na operação semicontínua, o fermentador em batelada alimentada foi selecionado, FBF (Fed-Batch Fermeter). Os três tipos de operação de fermentação (em batelada, contínua e semicontínua) avaliaram-se em função do rendimento, produtividade e tempo de operação. O critério do tempo de operação discriminou-se em tempos totais de fermentação para os fermentadores SBF e FBF, em quanto ao fermentador CSTF o tempo de retenção hidráulica foi usado. Tanto os modelos da cinética da fermentação, como os parâmetros cinéticos foram tomados da literatura e adaptados ao tipo de regime avaliado. Para a explicação da pervaporação foi usada a teoria de solução-difusão, pois segundo a literatura , é a teoria mais apropriada e simples que descreve a transferência de massa através da membrana em uma pervaporação. Os modelos de transferência de massa de Fick e Maxwell-Stefan (MS), foram aplicados para determinar a taxa de transferência de massa na pervaporação, baseada nas características das membranas de PDMS. As permeabilidades do modelo de transferência de massa de Fick foram determinadas. Os parâmetros de sorção e difusão do modelo de MS foram tomados da literatura. Para a membrana de PDMS avaliada, determinou-se um fator de separação de 3,5 para o etanol e 0,14 para água sob as condições normais de fermentação, indicando um fluxo de permeato com um conteúdo de água relativamente baixo (referente à solução fermentativa) e uma concentração de 33 wt.% de etanol no permeato. Fez-se o acoplamento da modelagem dos fermentadores SBF, CSTF e FBF com o modelo de MS da membrana de pervaporação. O modelo de MS apresentou maior exatidão que o modelo de Fick na transferência de massa através da membrana. Também propôs-se os esquemas da operação híbrida para os fermentadores H-SBMF (Hybrid -Simple Batch Membrane Fermenter), H-CSTMF (Hybrid- Continuous Stirred Tank Membrane Fermenter) e H-FBMF (Hybrid-Fed Batch Membrane Fermenter). Para a fermentação híbrida com membranas, além do rendimento, produtividade e tempo de operação foi avaliada a intensificação de etanol. Para o H-SBMF, a produção de etanol aumentou 14,43% em comparação à fermentação convencional, sob as mesmas condições operacionais (Intensificação de etanol) e a produtividade teve um incremento de 2,5 vezes. O H-CSTMF apresentou um incremento máximo de etanol produzido de 30,32%, e a produtividade foi incrementada em uma faixa de 1,1 a 1,7 vezes baseado no tempo de retenção (residencia hidráulica). No H-FBMF atingiu-se até 16,13 % de etanol intensificado e um incremento de 1,6 vezes na produtividade. Os rendimentos de todas as fermentações mantiveram relativamente constantes. Os consumos energéticos (energia térmica e mecânica) foram avaliados com base nos requerimentos energéticos da pervaporação, e consumo energético na etapa de destilação para obter álcool hidratado. Conseguiu-se advertir que houve um declínio do consumo de energia térmica (calor) do processo geral (máximo de 11%), em virtude de um significante aumento da quantidade de etanol produzido na fermentação híbrida. Determinou-se que o consumo de energia na recuperação do permeato, depende explicitamente da área da membrana, o qual foi média de 0,77 kW/m2. / In this study, an analysis of performance of the membrane technology insertion to conventional ethanol production technology has been developed. Membranes separation were considered to enhance the fermentation and distillation areas of conventional process of alcohol-fuel production. Aimed an intensification of alcoholic fermentation by pervaporation with PDMS (Polydimethylsiloxane) membranes, as a back-up technology to accomplish this assignment. Three fermentation operation arrangements were picked and assessed as intensification alternative operation, SBF (Simple Batch Fermenter) for transient regime, CSTF (Continuous Stirred Tank Fermenter) for steady-state fermentation and FBF (Feed Batch Fermenter) for semicontinuous operation. These three types of operation (batch, steady-state and semicontinuous) were evaluated as function of product-yield, productivity and operation time criteria. In batch and fed-batch operation, operation time was specified by total fermentation time, for steady-state operation the operation time criteria was residence time. Fermentation kinetic models and kinetic parameters were obtained from literature and embedded to assessed operation regimes. Pervaporation phenomena was explained by the solution-diffusion theory, since according to literature it is most appropriate and simple theory to describe the mass transfer across pervaporation membranes. Fick and Maxwell-Stefan mass transport model were used to determine the pervaporation mass transfer rate, based in PDMS membranes characteristic. Permeability from Fick model was calculated and sortion and diffusivity parameters from Maxwell-Stefan were obtained from literature. For evaluated PDMS membrane, ethanol and water separation factor of 3.5 and 0.15 were achieved, respectively for a range of normal fermentation concentrations, suggesting a permeate flux with lower water containing than fermentative solution and an ethanol concentration about to 35 %. SBF, FBF and CSTF modeling, Fick and Maxwell-Stefan membrane pervaporation models were adapted and applied together. In addition, a schematic hybrid arrangement for fermenters, H-SBMF (Hybrid -Simple Batch Membrane Fermenter), H-FBMF (Hybrid-Fed Batch Membrane Fermenter) and H-CSTMF (Hybrid-Continuous Stirred Tank Membrane Fermenter) was proposed. Further product-yield, productivity and operation time criteria, performance of membrane pervaporation was evaluated in hybrid-fermentation process. For H-SBMF, product-yield referred to conventional fermentation, under the same operative conditions (ethanol profit) increased 14.43% and 2.5 times higher productivity was achieved. H-CSTMF presented 30.32% higher ethanol profit; instead, the productivity had an increased in range of 1.1-1.7 times. For H-FBMF achieved 16.13% and 1.6 times higher ethanol profit and productivity, respectively. Fermentation energy consumption was estimated based in the energetic needs in pervaporation and energy demand in distillation area, for hydrated ethanol. A decrease of global energy consumption was attended (up to 11%), consequent to a quietly higher ethanol-feed concentration, generated in a simultaneous fermentationpervaporation process. The pervaporation was integrated to high-temperature compressed permete stream, reaching a higher energy-efficient process than a non-integrated pervaporation process. Electrical consumption for permeate recovery was determined and it is only in funtion of membrane area, achieving 0.77 kW/m2.

Ces travaux de thèse, financés par la Région Aquitaine et partie intégrante des projets ASCOBAR et OSQUAR (2007-2009 et 2009-2011), ont été effectués au sein du laboratoire IMS-Bordeaux (Université Bordeaux 1, CNRS, UMR 5218) et sont le fruit de la collaboration de trois laboratoires. Ils ont visé l'étude d'une plateforme à ondes acoustiques transverses horizontales guidées, ou ondes de Love, dédiée à la détection de phycotoxines responsables d'empoisonnement par consommation de chair de coquillage.Cette plateforme intègre une partie microfluidique destinée à assurer un contrôle du flux de l'échantillon d'analyse au voisinage de l'interface sensible, tout en réduisant les volumes utilisés. Des tests de détections ont été réalisés, en collaboration avec le Laboratoire d'Immunologie-Parasitologie de l’Université Bordeaux 2, en équipant le capteur d'un biorécepteur spécifique de type anticorps, commercial pour la détection d'acide okadaïque, ou, pour l'acide domoïque, fabriqué à partir d'un haptène formé avec un mimotope d'une famille de toxines du type amnésiante (ASP) synthétisé par l'Institut des Sciences Moléculaires (Université Bordeaux 1, CNRS UMR 5255).Grâce aux efforts synergiques de ce consortium et à l'élaboration de protocoles de détections spécifiques, les premiers résultats permettent de discriminer un échantillon empoisonné au seuil sanitaire, soit 0,2 ppm pour l'acide okadaïque, 20 ppm pour l'acide domoïque (200 ng d'acide domoïque dans seulement 10 mg de chair de coquillage). / These works have been funded by "la Région Aquitaine" as part of the projects ASCOBAR (2007-2009) and OSQUAR (2009-2011). They have been done in the IMS-Bordeaux (Université Bordeaux 1, CNRS, UMR 5218) with the collaboration of two others laboratories.The main goal was to create a guided transverse horizontal acoustic wave (Love wave) platform for specific detection of phycotoxins, responsible of shellfish poisoning. The microfluidic chip integrated into this platform allows control of the sample flow above the sensitive surface while saving biological liquid consumption.Detection tests have been done with the collaboration of the "Laboratoire d'Immunologie-Parasitologie" (Université Bordeaux 2). The sensitive surface was made of antibodies, created from a hapten made with a mimotope synthesized by "l'Institut des Sciences Moléculaires" (Université Bordeaux 1, CNRS UMR 5255). This mimotope is a molecule part which is common to a family of amnesic phycotoxin (ASP).Thanks to the synergistic efforts of this consortium and development of specific detection protocols, results can discriminate poisonous samples at sanitary threshold, that is, containing 0.2 ppm of okadaic acid, 20 ppm of domoic acid (200 ng of domoic acid into only 10 mg of shellfish flesh).

Marine biofouling is the accumulation of organisms onto surfaces immersed in sea water. Fouling of ships causes an increase in hydrodynamic drag which leads to performance issues such as increased fuel consumption and a reduced top operating speed. Fouling-release (FR) coatings are one way that paints have been used in combating biofouling by allowing for the easy removal of settled organisms. Traditional FR coatings are silicone elastomers which are soft, easily damaged, and require a tie coat for adhesion to marine primers. Siloxanepolyurethane FR coatings have shown promise as FR coatings, providing enhanced durability and toughness, better adhesion to marine primers, and comparable FR performance to commercial coatings. Preliminary studies were conducted to explore the use of PDMS macromers in the preparation of siloxane-polyurethane FR coatings. Attachment and removal of fouling organisms on the siloxane-polyurethane coatings based on PDMS macromers was comparable to commercial FR coatings. Extended water aging was also carried out to determine effects of extended water immersion on the fouling-release performance of the coatings. At up to four weeks of aging, the FR performance of the coatings was not affected. Static immersion marine field testing was performed to determine the fouling-release performance of siloxane-polyurethane coatings prepared with PDMS macromers. The performance was found to be comparable to commercial FR coatings for up to one year, including water jet removal of slimes, barnacle push-off removal, and soft sponging. The coatings showed good fouling-release performance until extremely heavy fouling was allowed to settle. Underwater hull cleaning was conducted for one siloxane-polyurethane composition identified as a top performer from static field testing. The coating was easily cleaned of fouling with rotating brushes for six months. The cleaning capability of the coating was reduced when large barnacles and other extremely heavy fouling was present. A commercial FR coating became heavily damaged with brush cleaning while the siloxane-polyurethane coating remained mostly undamaged. With more frequent cleaning, it is suspected that siloxanepolyurethane coatings would show cleaning capability for longer periods of time. Pigmentation of siloxane-polyurethane coatings based on difunctional PDMS and PDMS macromers was explored to investigate the effect on FR performance. Pigmentation with titanium dioxide caused a slight decrease in FR performance in some cases, but this was easily overcome by the addition of slightly more PDMS in the coating binder, thus illustrating the feasibility of siloxane-polyurethane coatings as effective, pigmented FR coatings. Finally, the exploration of unique PDMS polymer architectures has been explored for the development of additional, novel, fouling-release coatings. The incorporation of end-functional PDMS homopolymer molecular brushes and branched PDMS macromers into siloxane-polyurethane fouling-release coatings shows promise for the development of unique coatings where improved FR performance may be obtained. / Office of Naval Research (U.S.)

Manual collection and processing of seawater samples for dissolved gas analyses are technically challenging, time consuming and costly. Accordingly, in situ analysis techniques present attractive alternatives to conventional gas measurement procedures. To meet the demands of sustained, high-resolution chemical observations of the oceans, the University of South Florida and SRI International developed underwater mass spectrometer systems for quantitative measurements of dissolved gases and volatile organic compounds. This work describes the influence of variable in situ conditions on the performance of a membrane introduction mass spectrometer used for measurements in both the water column and sediment porewater. Laboratory experiments to simulate the effects of field conditions on the membrane were performed by varying sample flow rate, salinity, hydrostatic pressure, and chemistry. Data indicate that membrane permeability has a strong dependence on hydrostatic pressure, and a weak dependence on salinity. Under slow flow conditions bicarbonates in solution contributed to carbon dioxide instrument response as a result of carbon system equilibration processes in the boundary layer at the membrane interface. In addition, method development was undertaken to enable underwater sediment porewater analyses and quantitative (calibrated) measurements of total dissolved inorganic carbon (DIC). This work establishes the capability of membrane introduction mass spectrometry to measure two compatible variables (DIC and dissolved CO2) for comprehensive CO2-system characterizations. In addition to laboratory studies three types of field observation were obtained in this work. High-resolution vertical profiles of dissolved gases in the Gulf of Mexico were obtained through system calibration and characterization of the influence of hydrostatic pressure on the behavior of polydimethylsiloxane membranes. In the South Atlantic Bight, sediment porewater profiles of dissolved gases were repeatedly obtained over a 54 hr period. Data trends were in agreement with high remineralization rates facilitated by porewater advection. Finally, time-series underwater DIC measurements that were undertaken proved to be in good accord with results obtained using conventional techniques. These measurements constitute the first quantitative observations of dissolved gas ocean profiles, sediment porewater profiles, and DIC measurements by underwater mass spectrometry.

Thermal interface materials (TIMs) are used as an aid in transporting heat away from a circuit or electronic module. Composite materials are a popular research area for TIMs because they allow the desired properties from the individual constituents to be combined. The composite selected for this study uses carbon nanotubes (CNT) as the filler and an elastomeric polymer for the matrix, specifically a multiwalled carbon nanotube (MWCNT) / polydimethylsiloxane (PDMS) composite. Additionally, functionalization of the CNT may affect the composites’ thermal conductivity because of its effect on the CNT dispersion in the polymer matrix and its effect on the CNT-polymer interface. The objective of this study was to determine the effect CNT functionalization has on the effective thermal conductivity of a MWCNT/PDMS composite. The three functionalization’s used in this study are unfunctionalized, functionalized with a carboxyl group, and functionalized with a hydroxyl group. Secondary objectives were to develop the initial stages of a carbon-polymer composite database and to perform an uncertainty analysis on the stepped bar apparatus used in this study. The database is to be used for visualization of data found in literature to promote data driven research. The uncertainty analysis on the stepped bar apparatus is to qualify the instrument for thermal measurements in this study Initial results showed some increase in thermal properties of the composite, but there was little difference between the thermal conductivity of the three functionalization’s because of the high level of uncertainty used early on in this study. Later results showed an increase in mechanical properties of the composite which offset any thermal advantage with use as a TIM. A stronger composite means less compression under a similar load, resulting in a thicker TIM and higher resistance. However, the mechanical and thermal properties compound to show that -OH functionalized MWCNT present better properties for a TIM than unfunctionalized and -COOH functionalized; none show better results than the polymer by itself.

<p>Improved materials for implantation as intraocular lens (IOL) devices are needed to minimize the occurrence of posterior capsule opacification (PCO). In this work, novel polydimethylsiloxane (PDMS) loaded with matrix metalloprotease inhibitors (MMPI) were developed as model IOL materials.</p> <p>PDMS was chosen as silicones are currently used successfully as IOLs. Inhibitor release rates and amount of initial burst of drug-loaded PDMS could be controlled by changing solvent when loading into elastomer base, as well as drug loading method, and release buffer.</p> <p>Two lens epithelial cell lines were characterized for in vitro tests: FHL124 and HLE B3. These cell lines produce different combinations of extracellular matrix proteins when grown on various biomaterial surfaces. Significant differences between the two cell lines were observed both in collagen VIII and α-smooth muscle actin levels, both when cells were unstimulated, and as a result of epithelial to mesenchymal transition induced by treatment with transforming growth factor β2. FHL124 cells were selected in further tests due to their consistent expression of extracellular matrix components when exposed to different materials.</p> <p>Solutions of synthetic MMPI GM6001 and MMP 2/9 Inhibitor II, known to mitigate anterior subcataract formation, were released from PDMS and found to protect in a modest but significant way against protein profile changes and to delay migration. Due to the Zn²⁺ dependence of MMPs, chelators, including EDTA, TPEN and 1-10 phenanthroline were examined as alternative inhibitors. Only the latter was found to have a significant effect on cell migration rates in vitro. Sulfadiazine, due to its chemical resemblance to synthetic MMPI was determined to be the most efficient at reducing migration rates as well as to have the lowest toxicity.</p> <p>Overall, sulfadiazine was determined in this work to be a potentially effective solution to mitigating PCO. These results indicate that releasing MMPI molecules from PDMS as a model IOL is a promising way to mitigate aspects of PCO.</p> / Thesis / Doctor of Philosophy (PhD)

No description available.