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Low Salinity WaterFlood (LSWF) injection is an Enhanced Oil Recovery (EOR) method proven to be effective by extensive experimental studies. Correct implementation of this method in reservoir-scale simulations requires reliable estimation of relative permeability data. However, due to the ongoing debate regarding the dominant mechanism in this process and the inadequate understanding of complicated brine-oil-rock interactions, only a few models have been suggested to estimate relative permeability associated with LSWF for either carbonate or sandstone rocks. Existing models simulate the impact of LSWF based on geochemical interactions; however, the fluid-fluid interaction has been overlooked. Some models depend on the cation-exchange capacity of clay which is not adequate for clay-free rock. In contrast, others are based on weighting factors such as the divalent ions desorption, which is case dependent. This study presents a novel semi-empirical model of LSWF relative permeability, after high salinity water flooding, based on incremental oil recovery measured during low salinity injection. Therefore, it can be applied to all rock types, fluid systems, and wettability conditions regardless of the active mechanism. The relative permeability at the high salinity water flooding, krHS and incremental oil recovery during low salinity injection were inputs to the model for predicting the low salinity kr curve, krLS and, consequently, this model can be used to assess the performance of LSWF. Well-known mechanisms in literature on the incremental oil recovery during LSWF are reviewed including micro-dispersion. In this work, correlation between the incremental oil recovery and the amount of micro-dispersion has been employed for sensitivity analysis, and evaluation of the new model's response among various levels of incremental oil recovery. This new model has been validated utilising 12 coreflood datasets obtained from core flooding experiments under both unsteady-state and steady-state flooding conditions or protocols. A new steady-state experiment has been performed in this study to produce the first reliable relative permeability data that is needed for validation. This dataset, along with the unsteady-state dataset obtained under tertiary and secondary mode by other researchers in our group at Heriot-Watt University, has been used to validate the new model and to quantify the effect of LSWF injection on the relative permeability. Five experiments have already been published in literature by other researchers from our group, while the other four experiments have not yet been published. Additional two more experimental data from other group researchers available in the literature were deployed for further verification. Due to its mechanism independence, the new model suggested in this thesis can be applied for efficient performance screening of all LSWF injection scenarios, which is invaluable for the oil and gas industry's decision-making process. The results confirm the difference in relative permeability curves between high-salinity and low-salinity injections caused a decrease in water relative permeability and an increase in the oil relative permeability. They also prove that low-salinity brine can shift the rock wettability from oil-wet or mixed-wet towards a more water-wet condition. The obtained relative permeability curves extend across a substantial saturation range, making this valuable information necessary for numerical simulations. To the best of our knowledge, the data from the steady-state experiment is a first in assessing the impact of low-salinity waterflooding at a steady-state condition using a reservoir live crude oil and long reservoir core sample at reservoir condition. The results of this study are of utmost importance for the oil and gas industry.

Synaptic plasticity is a crucial neuronal mechanism for learning and memory. It allows synapses to change their strength over time. This dissertation focuses on a particular form of synaptic plasticity called synaptic scaling, a homeostatic mechanism that preserves relative synaptic strengths in an activity-dependent manner. Synaptic scaling is fundamental for neuronal stability, regulating other plasticity mechanisms like Hebbian plasticity or long-term potentiation (LTP). The aims of this dissertation are to explore the implications of synaptic scaling (and other forms of plasticity, such as structural plasticity) on the overall behavior of neurons. This is done using system-theoretic tools and feedback control. We first formulate a biophysical closed loop model of synaptic scaling. We then study how synaptic scaling affect neurons' behavior in both abstract and reconstructed morphologies. This study reveals important tradeoffs between robustness, convergence rate, and accuracy of scaling. We first look at synaptic scaling as a "global control action" whose main role is to guarantee a steady level of neural activity. We then consider activity-dependent degradation as a "local control action" whose role is to assist the neuron in fine-tuning different desirable spatial concentration profiles. We show that, in extreme scenarios, it can promote a level of competition between synapses that has a destabilizing effect on the overall behavior. At the methodological level, we use compartmental modeling and we focus on the in- teraction between feedback and transport, in linear and nonlinear settings. Using classical system-theoretic tools like Bode and Nyquist analysis and singular perturbation arguments, and more recent tools like contraction and dominance theory, we derive parameter ranges under which synaptic scaling is stable and well-behaved (slow regulation), stable and oscilla- tory (aggressive regulation), and unstable (pathological regulation). We also study the system robustness against static and dynamics uncertainties. Finally, to understand how different plasticity mechanisms simultaneously affect the neuron behavior, we study synaptic scaling in the presence of activity-dependent growth (mimicking a structural plasticity mechanism). This is a third layer of control action shaping the neuron morphology. We find that activity-dependent growth improves the neuron's performance when synaptic scaling is insufficient.

The research presented in this thesis is a collection of many different, yet connected, parts that stemmed from the development of a new alternative material intended to be utilised as anode material in solid oxide fuel cells. The main part is the research conducted in the development and characterisation of the novel A-site deficient La₀.2₂Sr₀.₇₋ₓCaₓTiO₃. Calcium introduction resulted in reducing this perovskite unit cell volume which, at the beginning, enhanced its electrical conductivity in reducing conditions. However, the ideal cubic symmetry coud not be maintained, as in the starting material LA₀.₂Sr₀.₇TiO₃, as a result of the increased A-site ionic radius mismatch and two lower symmetries were observed at room temperature. These were the tetragonal I4/mcm for 0.1 ≤ x ≤ 0.35 and orthorhombic Pbnm for 0.4 ≤ x ≤ 0.7. Higher temperature NPD data showed that the orthorhombic samples transformed into higher symmetries with Pbnm → I4/mcm → Pm3-m phase transitions. Detailed crystallographic analysis is discussed; where the different unit cells showed changes to the tilts of the BO₆ octahedra, along with distortions to these octahedra. DC conductivity measurements showed a high electrical conductivity of 27.5 S/cm for a pre-reduced composition La₀.₂Sr₀.₂₅Ca₀.₄₅TiO₃ at 900°C and pO₂ = 10⁻¹⁹ atm. This material showed very encouraging features; which makes it a very promising anode material for SOFCs. A study was also done which explores the best renewable energy options for the United Arab Emirates given its local climate and other aspects. The reliance on seawater desalination is argued to by unsustainable for different reasons. Thus, water security should be a main element in the planning process for adopting renewable energy technologies. A system that combines different technologies; with a focus on fuel cells technology; is outlined which is thought of to be a very promising basis for a broader system that will secure power and water in a very environment friendly way. Different compositions of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ were also studied using AC impedance spectroscopy in order to establish whether or not this system can show a ferroelectric behaviour. Results showed a variation in the dielectric constant of different samples with temperature; however, no Curie point was observed. Nonetheless, the results did show that the different compositions were very homogeneous when fully oxygenated and there were some indications of possible symmetry changes at sub-ambient temperatures. The final part of this thesis outlined the work done towards the development of a new analytical instrument. An existing TGA instrument was altered in order to provide a simultaneous thermogravimetric analysis and DC conductivity measurement for solid solutions at controlled temperature and oxygen partial pressure. Results were obtained for different samples of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ which showed a great dependence of the electrical conductivity on the oxygen stoichiometry in these oxides. Also, a direct method is possible with this instrument to estimate the oxygen chemical diffusion coefficient using the electrical conductivity relaxation method. This new setup will be very useful for different electrochemical and thermal studies which can broaden the understanding of the different mechanisms that affect the performance of different solid state materials.

Background: Serum phagocyte-derived alarmins S100A8/9 and S100A12 are considered useful for the assessment of inflammatory diseases. Our study evaluated the use of S100 proteins in a pediatric clinical setting for estimating disease activity and supporting diagnosis. Methods: Patients (n=136) who had S100 proteins tested as part of clinical care were included in this study and relevant information obtained from the medical record: C-reactive protein (CRP), disease activity status (inactive: = 0 joint; active: >0 active joint), systemic symptoms in systemic JIA (sJIA), and symptoms of flare of other autoinflammatory and fever syndromes. Patients were categorized as: sJIA, non-systemic JIA (nsJIA), other defined autoinflammatory syndromes (AID) and systemic undifferentiated recurring fever syndromes (SURFS). Results: Patients with sJIA (n=21) had significantly higher levels of S100A8/9 and S100A12 compared to patients with nsJIA (n=49), other AIDs (n=8) or SURFS (n=14) (all p