Listeria monocytogenes is the causative agent of listeriosis, a severe foodborne infection that is increasing significantly in Europe and North America. A correlating factor contributing to the resurgence of listeriosis is the rise in consumption of cold-stored ready-to-eat (RTE) foods. The steady upsurge in disease requires more focused research to control the pathogen, L. monocytogenes. Currently, there is a plethora of diagnostic methods for the causative agent, however, each has limitations, one of which is the inability to correlate results across laboratories. This is a particular hindrance to an outbreak investigation in an age when food is transported widely across the globe. In this study, proteomic approaches were used to search for biomarkers that facilitate rapid characterisation of isolates against a background of differentially expressed proteins. A preamble to this investigation necessitated incorporation of an efficient lysis procedure to release maximum proteins. This was eventually achieved using a Listeria specific enzyme, endolysin, and a disruptive mechanical method. Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) data showed that bead beating and enzymatic lysis were the most efficient methods for analysis of the proteome. Dendrogram lineages, derived from MALD-TOF-MS spectra, strongly correlated with 16S rRNA analyses. Selective protein capture and analysis by MALD-TOF-MS (designated SELDI-TOF-MS) demonstrated considerable intraspecies diversity as revealed by dendrograms which were also visualised by „Heat Maps‟. One-dimensional polyacrylamide gel electrophoresis and LC-MS/MS analysis of seven L. monocytogenes isolates, led to the successful identification of two proteins; a hypothetical protein, designated lwe06778 and a phosphoribosyl-AMP cyclohydrolase which were uniquely present at 4°C. This finding suggests that L. monocytogenes depends on the histidine biosynthesis pathway in order to survive at cold temperatures. It is hypothesised that the addition of inhibitors, specific to both proteins in RTE cold foods may be a useful means for controlling outbreaks of listeriosis in the future.

Recent advances in innovative energy storage devices such as supercapacitors have made battery-supercapacitor hybrid energy storage systems technically attractive. However the field of hybrid energy storage system control is relatively new, involving the major challenge of developing control techniques optimised for improved battery-life or other performance metrics. This thesis presents the design and analysis of an actively controlled hybrid energy storage system. Detailed information is given regarding the system implementation and dynamic controls developed as a part of the research. Novel use of the sliding-mode or hysteretic current-controlled DC/DC converter is shown to provide a versatile and robust power electronic building block for the power-control hardware implementation. Current state of the art in the field has converged around a frequency-domain approach to the overall power sharing strategy within hybrid energy storage systems employing batteries and high-power, low-energy density storage such as supercapacitors, with benefits in terms of reduced battery current maxima and an (un-quantified) increase in battery life having been reported. This research extends previous studies by considering the frequency-domain approach in further detail and providing quantitative simulation results confirming how an estimated increase in battery cycle-life of ~18% can be achieved. A systematic simulation framework used for the development and assessment of novel hybrid energy storage system control strategies is described and demonstrated in the context of a remote wind power application. The hardware design of all systems considered is described in detail and demonstrated by experiment.

As societies depart from current economic models which are built around affordable and easily accessible fossil fuels to energy systems increasingly based on the use of renewable energies, the need grows for a wide-scale clean and sustainable energy vector. Hydrogen fulfils most of the needed equirements, but implementation and large scale penetration, especially for mobile applications, is precluded by technical issues. Among these, arguably the most complex is how to safely, economically and efficiently store hydrogen. Storage in a porous material offers some attractive features, which include fast kinetics, reversibility and moderate energy penalties. A new methodology to analyse hydrogen adsorption isotherms in microporous materials is presented in this thesis. The methodology is applied to hydrogen adsorption in different classes of high-surface area materials but could in principle be used for any supercritical fluid adsorbed onto a microporous material. To illustrate the application of the methodology, high-pressure hydrogen adsorption isotherms of four different materials were analysed, metal-organic frameworks MIL-101 and NOTT-101 and carbons AX-21 and TE7. The analysis extracts important information on the adsorptive capacities of the materials and compares them with conventional storage methods, which include compression, liquefaction and cryogenic compression. The methodology also aids in the calculation of the thermodynamics of adsorption, providing a more accurate calculation method than currently reported techniques, demonstrated with the calculation of the differential isosteric enthalpies for metal-organic framework NOTT-101. NMR and INS are used in a novel way at the same operating conditions of sorption experiments to validate the findings of the analysis. Both methods provide a qualitative validation for the analysis. Remarkably, the INS reveals that the adsorbed hydrogen in TE7 is in a solid-like state. GCMC simulations were also used to compare with the application and findings of the methodology, using silicalite-1 as a test material.

Fossil fuel will eventually become exhausted. Also, fossil fuels produce large amounts of carbon dioxide, which cannot only bring environment pollution, but can also cause global warming. Therefore, clean and renewable energy sources should be investigated. In this project, renewable wind power was considered. Wind energy is free, clean and available in large quantities, although it is difficult to use due to its stochastic variability. Energy storage can reduce this variability allowing energy production to match energy demand. In this study, different kinds of energy storage approaches were introduced, compared, and simulated by using half hourly wind data from the Met Office, UK, and half hourly load data from the University of Bath, UK. Hydrogen has higher mass energy density than all other energy storage methods. It is seen as a versatile energy carrier of the future, complementary to electricity and with the potential to replace fossil fuels due to its zero carbon emissions and abundance in nature. On the other hand, because hydrogen is the lightest element under normal conditions; the same amount of hydrogen must occupy a huge volume compared to other elements. The mature technology for converting hydrogen into electricity has high cost and low efficiency. These are big issues that limit the usage of hydrogen energy storage methods. Using wind and load data, a new algorithm was developed and used for sizing the wind turbine, and energy storage requirements. The traditional way to supply energy is distributing electricity, but in this PhD research, there are some discussions about a new method, hydrogen transport-hydrogen pipeline. From the results of the comparison and algorithm, a practical hydrogen energy storage system for the University of Bath network was proposed and designed. In the proposed design the energy from a wind turbine was directed to the load and the remaining excess power was used to produce hydrogen by water electrolysis. The hydrogen was stored in a high pressure compressed tank, and finally a hydrogen fuelled combined cycle gas turbine was used to convert the hydrogen to electricity. In this thesis, the dynamics of the complete hydrogen cycle energy storage and recovery mechanism are discussed, identifying potential applications such as power smoothing, peak lopping and extending power system controller ranges. The results of calculations of the payback time and revenue verify the feasibility of the designed hydrogen energy storage system. The main objective of the PhD was to design a practical hydrogen energy storage system for micro-grid applications. During this research, hydrogen energy storage was investigated to show that it does solve the problems arising from renewable energy.

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The increase in irrigated agriculture in Saudi Arabia is having a large impact on its limited groundwater resources. While large-scale water storage changes can be estimated using satellite data, monitoring groundwater abstraction rates is largely non-existent at either farm or regional level, so water management decisions remain ill-informed. Although determining water use from space at high spatiotemporal resolutions remains challenging, a number of approaches have shown promise, particularly in the retrieval of crop water use via evaporation. Apart from satellite-based estimates, land surface models offer a continuous spatial-temporal evolution of full land-atmosphere water and energy exchanges. In this study, we first examine recent trends in terrestrial water storage depletion within the Arabian Peninsula and explore its relation to increased agricultural activity in the region using satellite data. Next, we evaluate a number of large-scale remote sensing-based evaporation models, giving insight into the challenges of evaporation retrieval in arid environments. Finally, we present a novel method aimed to retrieve groundwater abstraction rates used in irrigated fields by constraining a land surface model with remote sensing-based evaporation observations. The approach is used to reproduce reported irrigation rates over 41 center-pivot irrigation fields presenting a range of crop dynamics over the course of one year. The results of this application are promising, with mean absolute errors below 3 mm:day-1, bias of -1.6 mm:day-1, and a first rough estimate of total annual abstractions of 65.8 Mm3 (close to the estimated value using reported farm data, 69.42 Mm3). However, further efforts to address the overestimation of bare soil evaporation in the model are required. The uneven coverage of satellite data within the study site allowed us to evaluate its impact on the optimization, with a better match between observed and obtained irrigation rates on fields with higher frequency of available data. The inclusion of novel remote sensing sources (e.g. CubeSats) that offer higher frequencies and higher resolution can also be explored to improve the methodology, although further validation of these systems is needed. The developed framework has the potential to be used as a water management tool to monitor groundwater losses over large remote regions.

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Typescript (photocopy). / Digitized by Kansas Correctional Industries