<p> The microstrip transmission line has been theoretically analysed using conformal transformation and variational techniques. The variational method has been used to compute the line capacitance, characteristic impedance and guide wavelength of the following microstrip structures: (i) Microstrip transmission lines having negligible and finite strip conductor thickness. (ii) Microstrip transmission lines on two layer dielectric substrates having negligible and finite strip conductor thickness.</p><p> The total losses incurred in microstrip lines on semiconductor substrates have been included. An experimental technique (based on the Deschamps method) for measuring the characteristic impedance of microstrip lines through a lossy junction using a high precision microwave reflection bridge has been described. Measurements of the characteristic impedance of microstrip lines on intrinsic germanium substrates have been carried out at 9.38 GHz, and good agreement between the theoretical and experimental results have been obtained.</p> / Thesis / Master of Engineering (MEngr)

The challenge of demolding during the cast molding process of silicone hydrogel contact lenses can be addressed with the application of hydrophobic coatings on the surface of lens mold. In particular, the adhesion between silicone hydrogel and silicate substrates was minimized by applying silane modification on the surface of silicate substrates. Peel tests were conducted to measure the adhesive strengths between silicone hydrogel and surface modified glass substrates. Water contact angle measurement and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the surface properties of silane treated glass substrates.Silicone hydrogel was obtained by curing macromer mixture under UV for 6 minutes, with UV intensity of 95.0 mW/cm2. The obtained silicone hydrogel had a modulus of 0.87±0.09 MPa, within the same range of commercial contact lenses. And the hydrogel with a UV curing time of 6 minutes was unable to be peeled off from clean glass substrates. The effects of silane type and concentration on coating effectiveness were investigated and the most effective types of silane were found to be triethoxyphenylsilane (TEPhS) and octyltriethoxysilane (OTES), with an optimal concentration of 5 wt%. The peel strength between silicone hydrogel and silicate substrates was reduced to below 15.5 N/m with the application of TEPhS and OTES coatings. However, these silane coatings were not durable enough. Silane coupling agents need to be reapplied before each curing process of silicone hydrogel. / Thesis / Master of Applied Science (MASc)

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Most proteins must fold into native three-dimensional structures to be functional. But, newly synthesized proteins are at high risk of misfolding and aggregating in the cell. Stress, disease or mutations can also cause protein aggregation. A cyanobacterial small heat shock protein, Hsp16.6, can act as a chaperone to prevent irreversible protein aggregation during heat stress. This thesis is focused on the properties of proteins that were associated with Hsp16.6 during heat stress, and which therefore may be “substrates” of Hsp16.6. Bioinformatics were used to determine if Hsp16.6 preferentially binds to proteins with certain properties, and biochemical studies were performed to investigate how the substrates actually behave with Hsp16.6 during heat stress. It was found that Hsp16.6 preferentially binds to proteins with higher molecular weight, higher acidity, higher percentage of charged residues (especially negatively charged residues), and a lower percentage of hydrophobic residues compared to all proteins encoded by the Synechocystis genome. Proteins bound to Hsp16.6 were also slightly enriched in VQL motifs. The potential substrate fructose bisphosphate aldolase class II (FBA) was expressed in E.coli and purified. FBA could be protected by Hsp16.6 from aggregation through forming a complex with Hsp16.6 during heat stress in vitro, consistent with it being a substrate of Hsp16.6. Another potential substrate, elongation factor G1 (EF-G1) was also expressed in E.coli and purified. EF-G1 did not form insoluble aggregates even at 47°C, but circular dichroism spectroscopy revealed the secondary structure has melted at this temperature, and the protein eluted earlier than unheated protein on size exclusion chromatography. Thus, EF-G1 appears heat sensitive, and may also be an in vivo substrate of Hsp16.6. Lastly, in vivo study studies were performed to determine the amount of FBA and EF-G1 in Synechocystis cells. Both proteins are abundant, with FBA levels (around 2% of total cell protein) being about twice that of EF-G1. Further in vivo experiments will be needed to confirm that FBA and EF-G1 are substrates of Hsp16.6.

This work describes the techniques of assembling colloidal gold on flexible polymeric substrates from solution. The process takes advantage of the strong affinity of gold to thiol and amino groups. Polymeric substrates were modified with silanes having these functional groups prior to Au attachment or in the case of poly(urethane urea) (PUU), no surface functionalization was required. This polymer has terminal amine and N-H groups on the polymer chain, which can act as coordination points for gold. Immersion in the colloidal gold solution led to the formation of a monolayer. Increased coverage was obtained by two methods. The first was a reduction or "seeding" process, where Au was reduced onto the attached particles on the surface. The second was using different linker molecules and creating a multilayered film by a layer-by-layer assembly. Three linker molecules of different lengths were used. Films fabricated using the smallest molecule had the least resistance whereas films fabricated with the longest molecule were not conductive. The resistance of these films may be varied easily by heating. Heating the films at temperatures as low as 120 °C caused a dramatic decrease in the resistance of over six orders in magnitude. Successful attachment of gold to PUU with very good adhesion properties was also demonstrated. The attachment of gold was stable in different solvents. Upon stretching the PUU-Au films, it was observed that there is a reversible resistance increase with strain and at a certain strain, the film becomes non-conductive. This sharp transition from conductive to insulating has potential applications in flexible switches and sensors. A hysteresis in the strain-resistance curves, analogous to the hysteresis in the stress-strain curves of the polymer was also observed. Using PUU as an adhesive agent, gold electrodes were successfully assembled on Nafion-based polymer transducers. These materials showed comparable actuation behavior to the electrodes made by the Pt-reduction method, with the added advantage of the ability to form patterned electrodes for distributed transducers. Patterning techniques were developed to form colloid-polymer multilayers for use in photonic crystal materials using selective deposition on patterned silane monolayers. Patterns of gold electrodes were also made on flexible polymers using a photoresist-based method. / Ph. D.