Due to high demand for planar structures with low loss, a considerable amount of research has been done to the design of substrate integrated waveguide (SIW) components in the mm-wave and microwave range. SIW has many advantages in comparison to conventional waveguides and microstrip lines, such as compact and planar structure, ease of fabrication, low radiation loss, high power handling ability and low cost which makes it a very promising technology for current and future systems operating in K-band and above. Therefore, all the work presented in this dissertation focuses on SIW technology. Five di erent antenna systems are proposed to verify the advantages of using SIW technology. First, a novel K-band end- re SIW circularly polarized (CP) antenna system on a single layer printed-circuit board is proposed. A high gain SIW H-plane horn and a Vivaldi antenna are developed to produce two orthogonal polarizations in the plane of the substrate. CP antennas have become very popular because of their unique characteristics and their applications in satellites, radars and wireless communications. Second, a K-band front-end system for tracking applications is presented. The circuit comprises an antenna array of two Vivaldi antennas, a frequency-selective power combiner, and two frequency-selective SIW crossovers, which eliminate the need for subsequent ltering. The integration of monopulse systems in planar, printed circuit SIW technology combined with the added bene ts of ltering functions is of great importance to the antennas and propagation community. Third, a phased array antenna system consisting of 24 radiating element is designed as feed system for reflector antennas in radio astronomy applications. A Ku-band antipodal dipole antenna with wide bandwidth, low cross-polarization and wide beamwidth is suggested as the radiating element. Forth, four di erent right-angled power dividers including in-phase and out-of-phase dividers as feed systems for antenna arrays are introduced. TE10 - to - TEq0 mode transducers are used for obtaining two, three, and four output dividers with phase control ability at K- and Ka-band. This feature is practical, for instance, when designing tracking systems since they are employed to obtain controllable phase distributions over the output ports. Fifth, a Ku-band beam steering antenna system which is applicable to use for wireless communications, radar systems, and also 5G applications is proposed. This antenna system uses variable reflection-type phase shifters which electrically steer the beam over a 50-degree scan range. Therefore, the SIW technology's reliability and also promising behavior in the microwave frequency range is proven for di erent applications. / Graduate

Substratos alternativos têm sido usados para promover um melhor estabelecimento de plantas em viveiros, de forma a assegurar que plantas sadias sejam transferidas ao campo. No caso do Citrus spp. Esta preocupação é real pela possibilidade do campo poder apresentar um histórico de doenças na área, tal como a Clorose Variegada do Citros causada pela Xylella fastidiosa (X.f.). Este estudo avaliou a adição de vermicomposto a um substrato comercial e o desenvolvimento de plântulas de quatro variedades de citros inoculadas ou não com X.f. em condições de casa-de-vegetação, por um período de 450 dias. Medidas biométricas do crescimento da planta e o uso de indicadores do balanço nutricional usando o programa DRIS - Diagnosis and Recommendation Integrated System foram aplicadas em plantas de 9 meses de idade. As variáveis estudadas foram: substrato vermicomposto (100%, 50%, 0%) , variedade (Baia, Pêra, Natal e Escape) e inoculação (com ou sem X.f.) em um total de 24 tratamentos (variedade x substrato x inoculação), com seis repetições. Quanto ao desenvolvimento das plantas, avaliou-se o diâmetro do caule, a altura da planta, a produção de biomassas das raízes e partes aéreas, a taxa de infecção natural por fungos micorrízicos naturais do solo, a concentração de macro e micronutrientes na parte aérea. Quando se usou vermicomposto (100% or 50%), efeitos positivos foram observados nos parâmetros de desenvolvimento das plantas. Por outro lado, a infecção micorrízica e DRIS foram inversamente correlacionadas indicando estar ocorrendo um desbalanço nutricional neste estádio de desenvolvimento das plantas. Não foi observado um efeito significativo da inoculação com X.f. no desenvolvimento das plantas ou mesmo nos parâmetros biométricos, exceto para os teores foliares de nitrogênio e fósforo, onde nas plantas inoculadas o teor foliar de nitrogênio (1,46%) foi maior em relação às plantas não inoculadas (1,30%) e para fósforo ocorreu o oposto (0,32% e 0,40%, respectivamente). / Alternative substrates have being used for a better establishment of plants at nursery stages, thus ensuring that healthier plants will be transferred to the field. In the case of Citrus, this is a concern especially when there is a past history of diseases at field conditions, such as Citrus Variegated Chlorosis caused by Xylella fastidiosa (X.f.). This study evaluated the addition of vermicompost to a commercial substrate and the performance of seedlings of four citrus varieties inoculated or not with X. f. at greenhouse condition, for a period of 450 days. Biometric measurements of plant growth and nutritional balance indicators using DRIS - Diagnosis and Recommendation Integrated System were performed in 9 month-old plants. Mycorrhizal infection by native vesicular-arbuscular fungi was also evaluated in all plants. The studied variables were: vermicompost substrate (100%, 50%, 0%), variety (Baia, Pêra, Natal and Escape) and inoculation (with or without X.f.), in a total of 24 treatments (variety x substrate x inoculation) with 6 replicates each. Growth development evaluated stem diameter, plant height, shoot and root biomass accumulations, arbuscular mycorrhizal infection, and macro and micronutrient concentration in the shoot. When using vermicompost (100% or 50%), positive effects were observed in the plant growth parameters. On the other hand, mycorrhizal infection and DRIS were inversely correlated to the substrate addition, indicating that nutrient imbalances may be occurring at this plant growth stage. No significant effect of X.f. inoculation was observed on the plant growth and the biometric parameters studied, except for increased foliar nitrogen content - 1,46% for inoculated and 1,30% for uninoculated plants, and decreased foliar phosphorus content - 0,32% for inoculated and 0,40% for uninoculated plants.

Dans cette thèse, nous étudions le couplage électron-phonon dans le graphène, et en particulier l’influence du substrat. Il s’agit de quantifier par des mesures opto-électroniques le couplage des électrons avec les modes de phonons du substrat, que ce soit les modes de phonons polaritons de surface (SPP) pour les substrats isotropes comme le SiO2 ou les modes de phonons polaritons hyperboliques pour les substrats fortement anisotropes comme le h-BN. Pour ce faire, nous commençons par une revue générale du couplage électron-phonon dans le graphène avant de détailler les différentes méthodes expérimentales utilisées durant la thèse. Puis, nous détaillons les différents régimes de couplage pour un échantillon de graphène sur SiO2 et nous mettons en évidence la nécessité d’étudier des substrats ultra-propres. Nous présentons enfin les résultats obtenus pour un échantillon de graphène sur h-BN dans lequel nous mettons en évidence, en plus du couplage aux HPP,un régime de couplage nouveau qui consiste en l’émission de phonons-polaritons hyperboliques dans un régime d’effet tunnel Zener-Klein / In this thesis we study the electron-phonon coupling in graphene and in particular theinfluence of the substrate in the aforementioned coupling. We want to quantify by optoelectronicalmeasurements the coupling between the phonon modes of the substrate. It might be the couplingwith Surface Phonon Polaritons (SPPs) in case of isotropic substrates as SiO2 or Hyperbolic PhononPolaritons (HPPs) in case of highly anisotropic substrates. We start by a review about the state of theart on electron phonon coupling in graphene. Then we introduce the different experimental methodsused during this thesis. We present experimental results on an graphene on SiO2 sample. We identifythe different coupling regimes and point out the necessity of working on ultra clean samples toinvestigate the high energy regimes. Finally we prensent experimental results on a graphene on BNsample where we identify a new coupling regime consisting in HPP emission in a Zener-Klein transportregime

Population growth over the past ~50 years accompanied by the changes in dietary habits due to economic growth have markedly increased the demand for fixed nitrogen. Aided by biological nitrogen fixation, the Haber-Bosch process has been able to fulfill these demands. However, due to its high temperature and pressure requirements, Haber-Bosch is an expensive process. Every year, approximately 2% of the total energy expenditure by man is used to manufacture fixed nitrogen. Biological systems, on the other hand, produce ammonia at ambient temperature and pressure with much higher efficiency than the Haber-Bosch process. Research in the field of biological nitrogen fixation could prove valuable in understanding the mechanism of the enzyme responsible, nitrogenase. This could eventually allow researchers to mimic the enzyme and fix nitrogen at standard temperature and pressure, which would lead to greater availability of fixed nitrogen and a better standard of living for mankind. As part of this research, nitrogenase of Azotobacter vinelandii was studied to understand the order of events in reduction of substrates and the conformational changes in the enzyme responsible for its ability to reduce said substrates at room temperature and pressure. This knowledge was used to study variant forms of nitrogenase that could be activated using controlled external reductants. This freedom from the biological reductant of nitrogenase opens the door for further research into the understanding and development of enzyme mimics that can reduce substrates at room temperature and pressure.

Considerable experimental evidence supports the concept that the growth of plants generally decreases progressively as the salt concentration of the substrate increases, but certain relationships between plant and substrate are still not fully understood. The chemistry of salt toxicity to plants involves many interactions both as to the quantity and kind of ions presented to the roots and those accumulated in the plants. Many plant species have shown sensitivity to excess accumulation of specific salts frequently encountered in saline soils. Thus Eaton (1942), Wadleigh, Hayward, and Ayers (1951 ) have shown most of the fruit trees to be susceptible to injury as a result of the accumulation of chloride ion. Wadleigh, et al. (1951) have reported orchard grass to be sensitive to calcium salts. Recently, Brown, Wadleigh, and Hayward (1953) have found calcium chloride more toxic to some fruit trees than isosmotic levels of sodium chloride. These and other studies have indicated a greater influence of specific ions than of the osnotic pressure of the solution.

This thesis concentrates on RF/microwave characterization and modeling of planar spiral inductors and pad stack parasitics. The inductors varied in size from 1.9 to 15.3 nH. Several approaches were examined for modeling the planar spiral inductors. The approach developed herein is built around an existing composite model (available in commercial computer-aided design software), with added series and shunt impedances at both the input and output of the existing composite model. Artificial neural network (ANN) software was used to determine the correction impedance values. Another approach investigated was to model the S-parameters of the inductor using a space- mapping model of the input parameters for the existing model. The correction impedance modeling approach was theoretically sound but the level of accuracy need for the ANN model was not obtainable. The space mapping approach had merit but a substrate and parameter scalable model could not be achieved. A pad stack is a section of microstrip line that a surface mounted element is affixed to; these pad stacks are standardized for specific element sizes, so for example any 0805 (80 mils by 50 mils) element may have the same pad stack whether it is a capacitor, inductor or resistor. The pad stack models were necessary because a capacitor model originally developed at the University of South Florida did not include parasitic effects for different input connections. The pad stack parasitic models can be broken down into three types: dual-input, tri-input, and quad-input. Each of the dual- and tri- input models have input angles of either 0 degrees, 45 degrees, or 90 degrees. The models were developed using a combination of microstrip and lumped elements.

Lithium ion batteries (LIBs) have gained increasing popularity due to their high potential, low self-discharge, zero priming and minimal memory effect. However, the emergence of electrical vehicles and hybrid electrical vehicles in the automobile industry, where LIBs are predominantly in use, instilled a need to improve LIB batteries by experimenting with new materials. Graphite, the commonly used anode material for LIBs suffers from low theoretical capacity (372 mA h g-1) and torpid rate performance. Germanium (Ge) seems to be a promising substitute of carbon due to its high theoretical capacity, high Li+ diffusivity and electrical conductivity. However, Ge undergoes large volumetric change (±370%). This causes deboning of the thin film Ge electrode from the substrate current collector, causing a rapid decrease in the electrolytic performance. The process of ion beam mixing claims to have overcome this problem. In our current study, the adhesion strength of Ge thin film over Nickel (Ni) substrate (with and without ion beam mixing) is being measured using nanoindentation and the superlayer indentation test. Nanoindentation is one of the popular techniques to measure the mechanical properties and adhesion of thin film coatings. In this technique, a very small indenter of a desired geometry indents the film/substrate pair and the work of adhesion is calculated by knowing the plastic depth of indentation and the radius of indentation. Superlayer indentation is analogous to normal indentation but with a highly stressed superlayer on top to restrict the out-of-plane displacements, it reduces the plastic pile up around the indenter tip. The results from our study strongly suggest the possibility of dramatically increasing the adhesion strength by ion bombardment, which can be achieved by atomic level intermixing of the film/substrate pair. These, in turn, suggest that Ge could be an effective successor to graphite in the near future.

The objective of this study is to compare the caloric expenditure and oxidative sources of underwater treadmill running and land-based treadmill running at maximal and submaximal levels. Underwater running has emerged as a low load bearing form of supplementary training for cardiovascular fitness, as a way to promote recovery from strenuous exercise while maintaining aerobic fitness, and as a way to prevent injury. Prior studies have reported conflicting results as to whether underwater treadmill running elicits similar cardiorespiratory responses to land-based running. It is important to further investigate the similarities and differences between the two to determine if underwater running is as efficient as land-based running for maintenance of fitness and for rehabilitative purposes. Purpose: To compare the caloric expenditure and oxidative sources of underwater treadmill running and land treadmill running during both maximal treadmill trials to exhaustion and during 30 minute submaximal treadmill trials. Methods: 11 volunteer experienced male triathletes, ages 18-45 were recruited as participants. Each completed 6 trials total which included a maximal and submaximal oxygen consumption trial for each of three conditions: running on a water treadmill with AQx® water running shoes, running on a water treadmill without shoes, and running on a land-based treadmill. Data analysis: Data was analyzed using repeated measures ANOVAs, paired t-tests, pairwise comparisons with bonferroni adjustments, and descriptive statistics were reported. Results: For maximal oxygen consumption trials VO2, RPE, RER, and BP were not significantly different between modalities. Maximal HR was found to be significantly different between modalities, and was shown to be greater on land than in the water. For submaximal VO2, trials HR, RPE, RER, and post BP were not found to be significantly different between modalities. Average VO2, total calories expended, and pre systolic BP were found to be significantly different, and were shown to be greater on land than in water. Conclusions: While maximal exertion running on underwater treadmills seems to elicit similar cardiorespiratory responses to running on land-based treadmills, differences were seen at submaximal exertion levels. It remains unclear whether underwater treadmill running can elicit similar training stimuli as land running at submaximal levels.

In this dissertation, I utilize digital holographic microscopy (DHM) to study the motility of biological cells. As an important feature of DHM, quantitative phase microscopy by digital holography (DH-QPM) is applied to study the cell-substrate interactions and migratory behavior of adhesive cells. The traction force exerted by biological cells is visualized as distortions in flexible substrata. Motile fibroblasts produce wrinkles when attached to a silicone rubber film. For the non-wrinkling elastic substrate polyacrylamide (PAA), surface deformation due to fibroblast adhesion and motility is visualized as tangential and vertical displacement. This surface deformation and the associated cellular traction forces are measured from phase profiles based on the degree of distortion. Intracellular fluctuations in amoeba cells are also analyzed statistically by DH-QPM. With the capacity of yielding quantitative measures directly, DH-QPM provides efficient and versatile means for quantitative analysis of cellular or intracellular motility. Three-dimensional profiling and tracking by DHM enable label-free and quantitative analysis of the characteristics and dynamic processes of objects, since DHM can record real-time data for micro-scale objects and produce a single hologram containing all the information about their three-dimensional structure. Here, I utilize DHM to visualize suspended microspheres and microfibers in three dimensions, and record the four-dimensional trajectories of free-swimming cells in the absence of mechanical focus adjustment. The displacement of microfibers due to interactions with cells in three spatial dimensions is measured as a function of time at sub-second and micrometer levels in a direct and straightforward manner. It has thus been shown that DHM is a highly efficient and versatile means for quantitative tracking and analysis of cell motility.

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.