The clinical evaluation of people with possible myocardial infarction (MI) is often limited by atypical symptoms and inconclusive initial electrocardiograms. A recent consensus from the American College of Cardiology has redefined acute MI to include cardiac markers as central to diagnosis. To address this clinical need, a sensitive microfluidic surface-enhanced Raman spectroscopy (SERS) nanochannel-based optical device is being developed for ultimate use as a point-of-care device for the simultaneous measurement of MI blood biomarkers. The device can provide enhancements of the Raman signal of the analyte measured of up to 1013 using a mechanical aggregation technique at the interface of nanofluidic structures enabling repeatable SERS measurements. Specifically in this research iterations of a sensitive, low volume SERS platform technology were designed that provided quantitative information across a specific range. With the SERS platforms studied, not only were SERS enhancements of up to 1013 achieved but also imprecision values of less than 10% across the 10-50 pM range using a ratiometric approach and qualitative detection down to 100 aM was achieved. Beyond assessment of SERS substrates, assay designs were investigated and characterized including, label-free techniques and competitive immunoassay formats. Lastly, detecting the SERS signal of multiplexed reporter molecules was investigated. By identifying the analyte and assay constraints the design and optimization of future assays will be aided using this SERS platform technology.

The focus of this thesis is on the optimization and fabrication of p-i-n amorphous silicon (a-Si:H) solar cells both on glass and transparent plastic substrates. These solar cells are specifically fabricated on transparent substrates to facilitate the integration of thin film batteries with these solar cells. To comply with plastic substrates, different silicon layers are optimized at the low processing temperature of 135 C. In the first part of the optimization process, the structural, electronic, and optical properties of boron- and phosphorous-doped, hydrogenated nanocrystalline silicon (nc-Si:H) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) at the substrate temperature of 135 C are elaborated. Additionally, in this part, the deposition of protocrystalline silicon (pc-Si) films on glass substrates are investigated. In the device integration and fabrication part of this thesis, the optimization process is continued by fabricating single junction devices with different hydrogen dilution ratios for the cell absorber layer. The optimum device performance is achieved with an absorber layer right at the transition from amorphous to microcrystalline silicon. To further improve the performance of the fabricated solar cells, amorphous silicon carbide buffer layers are introduced between the nc-Si p-layer and the undoped pc-Si absorber layer. Single junction p-p'-i-n solar cells are fabricated and characterized both on glass and plastic substrates. Our measurements show conversion efficiencies of 7.0% and 6.07% for the cells fabricated on glass and plastic substrates, respectively. In the last part of this research, the light trapping enhancement in amorphous silicon solar cells using Distributed Bragg Reflectors (DBRs) are experimentally demonstrated. Reflectance characteristics of DBR test structures, consisting of amorphous silicon (a-Si) / amorphous silicon nitride (SiN) film stacks are analysed and compared with those of conventional ZnO/Al back reflectors. DBR optical measurements show that the average total reflectance over the wavelength region of 600-800 nm is improved by 28% for DBR back structures. Accordingly, single junction amorphous silicon solar cells with DBR and Al back reflectors are fabricated both on glass and plastic substrates. Our results show that the short-circuit current density and consequently the conversion efficiency is enhanced by 10% for the cells fabricated on textured transparent conductive oxide substrates. In addition, these DBR back structures are designed and employed to improve the efficiency of semi-transparent solar cells. In this application, the optimized DBR structures are designed to be optically transparent for the part of the visible range and highly reflective for the red and infra-red part of the spectrum. Using these DBR structures, the efficiency of the optimum semi-transparent solar cell is enhanced by 5%.

In this study, barium strontium titanate (BST) thin films with different compositions (Ba0.9Sr0.1TiO3, Ba0.8Sr0.2TiO3, Ba0.7Sr0.3TiO3, Ba0.5Sr0.5TiO3) were produced by chemical solution deposition technique. BST solutions were prepared by dissolving barium acetate, strontium acetate and titanium isopropoxide in acetic acid and adding ethylene glycol as a chelating agent and stabilizer to this solution, at molar ratio of acetic acid/ethylene glycol, 3:1. The solution was then coated on Si and Pt//Ti/SiO2/Si substrates at 4000 rpm for 30 seconds. Crack-free films were obtained up to 600 nm thickness after 3 coating &amp / #8211 / pyrolysis cycles by using 0.4M solutions. Crystal structure of the films was determined by x-ray diffraction while morphological properties of the surface and the film-substrate interface was examined by scanning electron microscope (SEM). Dielectric constant, dielectric loss and ferroelectric parameters of the films were measured. Sintering temperature, film composition and the thickness of the films were changed in order to observe the effect of these parameters on the measured electrical properties. The dielectric constant of the films was decreased slightly in 1kHz-1 MHz range. It was seen that dielectric constant and loss of the films was comparable to chemical solution deposition derived films on literature. Maximum dielectric constant was obtained for the Ba0.7Sr0.3TiO3 composition at a sintering temperature of 800&amp / #730 / C for duration of 3 hours. Dielectric constant increased whereas dielectric loss decreased with increasing film thickness. BST films have composition dependent Curie temperature. For Ba content greater than 70 %, the material is in ferroelectric state. However, fine grain size of the films associated with chemical solution deposition and Sr doping causes the suppression of ferroelectric behaviour in BST films. Therefore, only for Ba0.9Sr0.1TiO3 composition, slim hysteresis loops with very low remanent polarization values were obtained.

ABSTRACT PREPARATION OF PLZT THIN FILMS BY CHEMICAL SOLUTION DEPOSITION AND THEIR CHARACTERIZATION Kaplan, Burkan M.S., Department of Metallurgical and Materials Engineering Supervisor: Prof. Dr. Macit &Ouml / zenbaS November 2005, 125 pages In this study, La3+ was substituted into lead zirconate titanate (PZT) system by Pb1-xLax(ZryTi1-y)1-x/4O3 nominal stochiometry and it was processed via chemical solution deposition on (111)-Pt/Ti/SiO2/Si-(100) substrate.PLZT solutions were prepared by mixing two solutions, one of which was obtained by dissolving lead acetate and lanthanum acetate hydrate in 2 methoxyethanol at high temperature. This solution was then mixed with the second solution containing zirconium propoxide and titanium isopropoxide. 40ml/0.4M solution was prepared and spin coated on Pt/Ti/SiO2/Si substrates at 3000 rpm for 30 seconds. After 4 coating cycles, film thickness was reached to 600 nm. A systematic study was carried out in different regions of PLZT phase diagram tetragonal, rhombohedral and on the morphotropic phase boundry (MPB) to obtain optimized results of ferroelectric, dielectric and optical properties of the material. During the period of the work, effect of parameters on these properties such as heat treatment conditions, chemical composition of the film, microstructure and thickness of the film was investigated. The films were characterized structurally and electrically. For structural properties, X-ray diffraction technique (XRD), energy dispersive spectrometry (EDS) and Scanning Electron Microscope (SEM) were used to observe phases and surface characterization. For electrical measurements, ferroelectric tester was used to obtain dielectric constant, loss tangent and hysteresis curves. Optical transmittance of the films was also investigated by UV-VIS Spectrophotometer and optical film constants were calculated by modified envelope method. It was observed that the optimum heat treatment conditions were achieved at 7500C for 3 hours. The highest ferroelectric and dielectric properties such as remanent polarization and dielectric constant were obtained using that temperature. The dielectric constant of the films was measured in the frequency range of 1kHz-1MHz and remained almost constant in this region. The change of dielectric constant and ferroelectric hysteresis loops were obtained as a function of Zr/Ti ratio and La content. The grain size as a function of sintering temperature and La content was investigated. It was seen that as the sintering temperature was increased, the grain size of the films increased. The same tendency was also observed when the La content was increased. Fatigue behavior of PLZT thin films was also investigated by Radiant Ferroelectric Tester at 50 kHz and &plusmn / 15V. Change of remanent polarization (Pr) as a function of cumulative switching cycles (N) was drawn with the log scale of x-axis. Furthermore, leakage current characteristics of the films were also obtained by the ferroelectric tester at &amp / #61617 / 15V. It has been observed that as the La content of the film was increased, leakage current of the PLZT films decreased. Keywords: PLZT, (111)-Pt/Ti/SiO2/Si-(100) substrate, Chemical Solution Deposition.

A Theory of Dropwise Condensation

The main purpose of this dissertation was to address key issues in the design and analysis of RF/microwave filters for wireless applications. Since RF/microwave filters are one of the bulkiest parts of communication systems, their miniaturization is one of the most important technological challenges for the development of compact transceivers. In this work, novel miniaturization techniques were investigated for single-band, dual-band, ultra-wideband and tunable bandpass filters. In single-band filters, the use of cross-shaped fractals in half-mode substrate-integrated-waveguide bandpass filters resulted in a 37 percent size reduction. A compact bandpass filter that occupies an area of 0.315 mm2 is implemented in 90-nm CMOS technology for 20 GHz applications. For dual-band filters, using half-mode substrate-integrated-waveguides resulted in a filter that is six times smaller than its full-mode counterpart. For ultra-wideband filters, using slow-wave capacitively-loaded coplanar-waveguides resulted in a filter with improved stopband performance and frequency notch, while being 25 percent smaller in size. A major part of this work also dealt with the concept of 'hybrid' RF MEMS tunable filters where packaged, off-the-shelf RF MEMS switches were used to implement high-performance tunable filters using substrate-integrated-waveguide technology. These 'hybrid' filters are very easily fabricated compared to current state-of-the-art RF MEMS tunable filters because they do not require a clean-room facility. Both the full-mode and half-mode substrate-integrated waveguide tunable filters reported in this work have the best Q-factors (93 - 132 and 75 - 140, respectively) compared to any 'hybrid' RF MEMS tunable filter reported in current literature. Also, the half-mode substrate-integrated waveguide tunable filter is 2.5 times smaller than its full-mode counterpart while having similar performance. This dissertation also presented detailed analytical and simulation-based studies of nonlinear noise phenomena induced by Brownian motion in all-pole RF MEMS tunable filters. Two independent mathematical methods are proposed to calculate phase noise in RF MEMS tunable filters: (1) pole-perturbation approach, and (2) admittance-approach. These methods are compared to each other and to harmonic balance noise simulations using the CAD-model of the RF MEMS switch. To account for the switch nonlinearity in the mathematical methods, a nonlinear nodal analysis technique for tunable filters is also presented. In summary, it is shown that output signal-to-noise ratio degradation due to Brownian motion is maximum for low fractional bandwidth, high order and high quality factor RF MEMS tunable filters. Finally, a self-sustained microwave platform to detect the dielectric constant of organic liquids is presented in this dissertation. The main idea is to use a voltage- controlled negative-resistance oscillator whose frequency of oscillation varies according to the organic liquid under test. To make the system self-sustained, the oscillator is embedded in a frequency synthesizer system, which is then digitally interfaced to a computer for calculation of dielectric constant. Such a system has potential uses in a variety of applications in medicine, agriculture and pharmaceuticals.

The use of gold-based nanoparticles and thin films is very promising when it comes to improving several green nanotechnologies. Therefore, in order to further their use in applications such as electrochromic devices, photovoltaics, light-emitting diodes and photocatalysis, the aim of this work was to study the growth of gold-based nanoparticles and thin films. All depositions were made using DC magnetron sputtering, and optical, structural, electrochemical, electrical and photocatalytic studies of the films and particles were performed. The various applications yield a variety of substrate properties, and how these substrate properties affect gold coalescence was studied by depositing gold on glass slides and on SnO2:In, ITO and TiO2 base layers. Temperature also affects the gold coalescence. Therefore, gold was deposited on heated and non-heated substrates, where the latter were also post-heated, with a temperature range between 25ºC and 140ºC in both cases. Various temperatures were also used for manufacturing gold nanoparticles, and their effect as photocatalytic improvers was tested on WO3 films. The optical properties of Au films on glass were determined by ellipsometry in the 0.25 – 2 µm range, and then a spectral density analysis was performed of the effective dielectric permittivity. This work showed that thin gold films are excellent replacements for oxide-based transparent conductors in electrochromic devices. It was also shown that thin homogeneous gold films were better conductors when they were deposited on glass, compared to when they were deposited on oxide base layers, regardless of the optical, electrical and structural properties, or the doping concentration of the base layers. The results also showed that thin gold films were durable at 76ºC, and hence hold for a typical window temperature of ~70ºC. For higher temperatures, gold deposition on heated and non-heated substrates resulted in a distinct difference in growth, and there was also a distinct difference between post-heated gold films produced at 25ºC, compared to when the films were deposited on heated substrates. In the latter case, an island structure was obtained at 140ºC. Spectral density analysis gave spectral densities of similar shape for nanoparticles and continuous gold films, which is useful information for further investigations.

Atrial fibrillation and atrial flutter are the most common sustained arrhythmias, however their underlying mechanisms are yet to be fully characterised. This thesis evaluates the electrophysiological and electroanatomical substrate of the atria in patients with these arrhythmias. Experimental studies of atrial fibrillation have demonstrated effective refractory period shortening and conduction slowing as a result of atrial fibrillation giving rise to the concept that "atrial fibrillation begets atrial fibrillation". However, cardioversion to prevent electrical remodelling does not prevent progression of disease, suggesting a "second factor" drives this process. Chapters 2 and 3 evaluate the atrial substrate in patients with "lone" atrial fibrillation. These studies demonstrate such patients, remote from an arrhythmic event, have prolongation of atrial refractoriness, conduction slowing, impairment of sinus node function, site-specific conduction delay, lower voltage and a greater proportion of complex electrograms compared to reference patients. These abnormalities constitute the "second factor" critical to the development and progression of atrial fibrillation. Atrial flutter has a close inter-relationship with atrial fibrillation and these rhythms frequently co-exist. Atrial fibrillation often occurs in patients with heart disease known to demonstrate abnormal atrial substrate; whether similar substrate exists in patients with atrial flutter to account for the co-existence of both arrhythmias is unknown. Chapters 4 and 5 evaluate the atrial substrate in patients with atrial flutter, remote from arrhythmia, demonstrating structural abnormalities characterised by loss of myocardial voltage, conduction slowing and impaired sinus node function, without reduction in atrial refractoriness. These findings implicate a common substrate as the cause of the close inter-relationship between these arrhythmias. There is a frequent association between atrial arrhythmia and sinus node disease for which several mechanisms have been postulated. In addition, there is a size discrepancy between the anatomical sinus node and the much larger functional sinus node complex. little is known about normal sinus node function or the effects of remodelling due to arrhythmia. Chapter 6 characterises sinus node activation to determine the nature and extent of the functional sinus node complex in patients with and without chronic atrial flutter. The functional sinus node complex demonstrates dynamic shifts in activation with preferential pathways of conduction to atrial myocardium. Patients with atrial flutter demonstrate lesser voltage, longer conduction times along preferential pathways and a smaller functional sinus node complex. These findings provide insights into the function of the human sinus node in health and disease. Sites of complex fractionated atrial electrograms and highest dominant frequency are implicated in maintaining atrial fibrillation. Chapter 7 determines the minimum recording duration that accurately characterises electrogram complexity and activation frequency. An electrogram duration of 5 seconds is required to accurately identify these sites. Chapter 8 evaluates the relationship between sites of fractionation and high frequency activation during atrial fibrillation. Greater fractionation and higher dominant frequency are seen in persistent atrial fibrillation and left atria. Preferential areas of high dominant frequency are observed in paroxysmal but not persistent atrial fibrillation. Areas of complex fractionated atrial electrograms are found adjacent to sites of high dominant frequency. / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2009

Glucocorticoids are widely used in clinical therapy. However, they cause adverse effects including insulin resistance and Type 2 diabetes, which are characterised by decreased glucose transport into the muscles and fat. How glucocorticoids inhibit glucose transport remains unclear. Insulin stimulates glucose uptake via the insulin receptor substrate (IRS)-1 / phosphoinositide-3-kinase (PI3K) / protein kinase B (AKT) pathway and promotes the redistribution of GLUT4 from intracellular storage compartments to the plasma membrane (PM). Insulin-stimulated phosphorylation of AKT substrate of 160 kDa (AS160), a Rab-GTPase activating protein is downstream of AKT and appears to be essential for exposure of GLUT4 at the PM and glucose uptake. This is mediated through the association of phosphorylated AS160 (at the key residue T642) with 14-3-3 in the cytosol. The mildly insulin-responsive GLUT1 mediates basal glucose uptake in adipocytes. It is also subject to regulated trafficking like GLUT4. This study aimed to determine the level at which glucocorticoids inhibit glucose uptake in adipocytes. Effects of the synthetic glucocorticoid dexamethasone (Dex) and the natural glucocorticoid cortisol, on GLUT1 and GLUT4 function were examined. Candidates for the glucocorticoid-mediated inhibition of GLUT1- and GLUT4-mediated glucose uptake were investigated. These were glycogen synthase kinase (GSK) 3β (an AKT substrate) for GLUT1-mediated glucose transport; and adaptor protein containing PH domain, PTB domain, and leucine zipper motif (APPL)-1 (an AKT-interacting protein) and AS160 for GLUT4-mediated glucose transport. Dex and cortisol significantly decreased basal glucose uptake by 50% (p<0.05) in SGBS and 3T3-L1 adipocytes. Similarly, insulin-stimulated glucose uptake was decreased by 50% (p<0.001 for SGBS; p<0.05 for 3T3-L1) and 30% (p<0.05 for both) at 1 nM and 100 nM insulin respectively. Similar results were observed with differentiated primary human preadipocytes and human adipose explants. Dex-mediated inhibition of basal glucose uptake was limited to insulin-sensitive cell types implying that glucocorticoids may regulate GLUTs at steps common to GLUT1 and GLUT4 trafficking. Dex-mediated reduction in glucose uptake correlated with the reduction in basal and insulin-stimulated expression of GLUT1 and GLUT4 to the PM without changes in total GLUT1/4 expression. Dex did not alter total expression or phosphorylation of proximal insulin-signalling molecules up to and including AKT but increased FOXO1 expression, and modified GSK3β-S9 phosphorylation. Dex did not alter total APPL1 expression or subcellular distribution. Dex significantly decreased 1nM-insulin stimulated AS160-T642 phosphorylation by 50% (p<0.05) in SGBS and 3T3-L1 adipocytes via the glucocorticoid repector (GR). This correlated with reduced AS160:14-3-3 interaction. Similar results were obtained for AS160-T642 basal phosphorylation. At 1nM insulin, AS160-T642 phosphorylation is maximal at sub-maximal glucose uptake, i.e. AS160 phosphorylation significantly contributes to glucose uptake. RU486 significantly prevented but did not fully abrogate the Dex-mediated reduction in glucose uptake suggesting additional Dex-induced defects. In conclusion, glucocorticoids inhibit glucose uptake at a level distal to AKT by GR-dependent mechanisms. A role for GSK3β or APPL1 in glucocorticoid-mediated inhibition of glucose uptake requires further investigations. FOXO1 represents a suitable candidate for mediating the Dex-induced defects. Of significance, perturbation in AS160-T642 phosphorylation contributes to Dex-mediated inhibition of glucose uptake. Thus, AS160 presents a novel therapeutic target in the improvement of glucocorticoid-mediated inhibition of glucose uptake.

Problem investigated: Chronic wounds are not only a major burden to the patient arising from general pain and discomfort but also generate economic costs to both these individuals and the health care system. Various electrical stimulation regimes have been employed to study the effects of electrical stimulation on wound healing both in vivo and in vitro. In was hypothesised that electrical stimulation using various waveforms can modulate cell function, particularly cell migration. The aim of this thesis was to study the effects of electrical stimulation on cellular migration, in particular endothelial cells and fibroblasts, key cell types involved in wound healing. The impact of collagen matrix on cell migration was also assessed. Methods: Cells were seeded on either glass or collagen I substrate and stimulated with various electrical regimes via platinum electrodes connected to a constant current source. Cell migration was accessed by manual tracking of cell nuclei over a period of 3 hours from digital time-lapse images acquired during stimulation. Data from cell tracking were analysed for directional migration, migration rates and mean square displacement. Results: No directional cell migration for both endothelial cells and fibroblasts were observed when stimulated with either alternating or biphasic currents. However, surface substrate had impacted on cell motility with opposite effects being observed for the two cell types. Endothelial cells tended to migrate at a faster rate on collagen I substrate than on glass, compared with fibroblasts, which displayed a slower rate of migration on collagen I substrate. Significant changes in mean square displacement of biphasic current stimulated cells on collagen I substrate compared to unstimulated cells were also observed. Conclusion: This thesis has illustrated cell migration can be modulated by electrical stimulation, in particular asymmetric biphasic current. It has also been demonstrated surface substrate can impact cell migration.