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The performance and broader application of dielectric barrier discharge (DBD) plasma actuators are restricted by the manufacturing methods currently employed. In the current work, two methodologies are proposed to build robust plasma actuators for active flow control; a protective silicone oil (PDMS) treatment for hand-cut and laid tape-based actuators and a microfabrication technique for glass-based devices. The microfabrication process, through which thin film electrodes are precisely deposited onto plasma-resistant glass substrates, is presented in detail. The resulting glass-based devices are characterized with respect to electrical properties and output for various operating conditions. The longevity of microfabricated devices is compared against silicone-treated and untreated hand-made devices of comparable geometries over 60 hours of continuous operation. Both tungsten and copper electrodes are considered for microfabricated devices. Human health effects are also considered in an electromagnetic field study of the area surrounding a live plasma actuator for various operating conditions.

The performance and broader application of dielectric barrier discharge (DBD) plasma actuators are restricted by the manufacturing methods currently employed. In the current work, two methodologies are proposed to build robust plasma actuators for active flow control; a protective silicone oil (PDMS) treatment for hand-cut and laid tape-based actuators and a microfabrication technique for glass-based devices. The microfabrication process, through which thin film electrodes are precisely deposited onto plasma-resistant glass substrates, is presented in detail. The resulting glass-based devices are characterized with respect to electrical properties and output for various operating conditions. The longevity of microfabricated devices is compared against silicone-treated and untreated hand-made devices of comparable geometries over 60 hours of continuous operation. Both tungsten and copper electrodes are considered for microfabricated devices. Human health effects are also considered in an electromagnetic field study of the area surrounding a live plasma actuator for various operating conditions.

The deterioration of cellulose nitrate artefacts in museum and art collections is a complex problem facing conservators and conservation scientists. This study has looked at several aspects of the degradation by analysing artefacts and model samples. Initial work concentrated on a survey of a collection of artefacts, many of which showed active degradation, by visual inspection and FTTR spectroscopy. A more thorough analysis of the artefacts was carried out, using ion chromatography, xray fluorescence spectroscopy and atomic absorption spectroscopy, to identify compositional differences between samples, which may relate to degradation. The results of these studies suggested that residual sulphate in the plastics is a cause of increased degradation. The presence of oxalate in degraded artefacts also indicated that chain scission is occurring during deterioration. Later work using gel permeation chromatography confirmed this. Work has also involved the use of accelerated ageing tests to study the effect of sulphate in the degradation and also the influence of inorganic fillers, iron and humidity. It has been concluded that the degradation of cellulose nitrate artefacts is dependent on the presence of sulphate and humidity. The process is diffusion controlled which indicates that loss of plasticiser is a vital factor. This work also suggests simple procedures that can be used to assess an artefact's stability.

The ubiquitin proteasome pathway is the predominant biological mechanism of myofibrillar protein (MF) degradation.  To test the hypothesis that amino acid and insulin act synergistically to regulate proteolysis, two experimental models were employed;  an <i>in vivo </i>study on growing calves and an <i>in vitro</i> C2C12 myotubes culture. Calves growing at 0.3kg/day, were constantly infused with glucose at a low (LDG) or high (HDG) dose (to stimulate insulin) with or without essential amino acids (EAA).  Glucose infusions increased plasma insulin and IGF-1 concentrations in a dose dependent manner (P<0.05).  HDG was associated with decreased plasma urea nitrogen and 3-MH concentrations and 3-MH:creatinine output (an index of MF degradation) (P < 0.05).  Glucose infusions down regulated the expression of 14-kDa E2 ubiquitin conjugating enzyme and C2 20 S proteasome sub unit, however EAA did not alter the effect of raised plasma insulin on muscle ubiquitin proteasome pathway suggesting that under the conditions employed, EAA do not act synergistically with insulin to decrease myofibrillar protein degradation, <i>in vivo.</i> In the <i>in vitro</i> experiments, amino acid deprivation (0.2 X physiological concentration amino acid;  PC AA) of myotubes for 8 h was associated with increased (P < 0.05) proteolysis (measured from TCA soluble ³H-tyrosine release in the medium), compared to controls (1.0 X PC AA).  Addition of insulin inhibited this increase (P < 0.05).  Rapamycin significantly increased proteolysis in 1.0 X PC AA media suggesting amino acid might regulate proteolysis through mTOR signalling pathway.  Reduced amino acid supply also increased 14-kDa E2 and C2 mRNA expression compared to controls (P < 0.05).  Increasing leucine concentration in 0.2 X PC AA basal media showed a dose dependent decrease in protein degradation and expression of 14-kDa E2, in the presence of insulin.  In conclusion, the results suggested that decreased availability of amino acids was associated with increased total proteolysis and that anti-catabolic effect of amino acid in C2C12 muscle cell cultures, was additive to that of insulin.

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No description available.

The work presented in this thesis was performed firstly to highlight the changes wrought in restored soil systems following the disruptive activities of opencast coal mining, and thereafter to identify, simulate and assess the effects of some typical perturbations associated with these activities. The microbial community was used as a focus for these investigations and the methods of soil adenosine 5'- triphosphate content analysis, dehydrogenase activity analysis and ergosterol content analysis were utilised alongside several other physical and chemical determinations. A field study of restored sites of various ages after cessation of opencast coal mining was undertaken which reinforced the utility of the microbial measurements. Experimentation was performed to investigate the effects of soil storage (at two depths), physical disturbance, compaction and the effects of the different combinations of these perturbations. Novel findings were obtained largely due to the paucity of research addressing the controlled manipulation and careful interpretation of these individual perturbations, and their effects when combined. The storage of soil was found to be the dominant factor influencing the status of the microbial communities upon restoration, and also influencing the development of these communities and the emergent plant biomass, post-restoration. This study found that soil, reinstated after opencast coal mining, becomes quickly dominated by fungi and, under grassland management, this domination then subsides over many years to a more bacterialcharacterised system. Differences were identified between the action of physical disturbance and compaction on stored and unstored soils. The deleterious effect of physical disturbance on unstored soil and the apparent ameliorative effect on soil affected by opencast operations can be interpreted through the change in soil architecture engendered by this treatment. The severe disturbances associated with opencast coal mining were found to affect the soil biota, primarily in terms of enduring environmental change. Thus the study of soil ecology was used as a sensitive indicator of recovery of disturbed land, and the changing energy flow through detrital food-webs was used as a model to follow this recovery process.

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This is a study of the relationship between livelihood strategies, soil fertility investment and land use in the village of Fandou Ben, southwestern Niger. The aim has been to place alleged soil degradation in a specific, differentiated and dynamic local context. The village, which is populated by Djerma and Fulani, has a low population density. The agricultural system is dominated by millet cultivation on poor soils. It now depends on short-fallow periods to restore fertility, other sources of inputs being limited. There are high erosion rates and an annual precipitation of 600mm with high variability. The local narrative can be interpreted to represent this landscape as a lifescape: an environment that is a product of a complex sequence of agricultural decisions and livelihood responses. The flexibility in the ways in which the farmers manage their soil is a reflection of the ephemerality of the factors that govern soil productivity and the need to adapt to natural biodiversity and spatial variability. They relied on their local knowledge to maximise productivity, as in their precision application of organic inputs, the ways in which they are increasingly integrating smallstock into their strategies, and the increasing signs of ethnic cooperation. Using a Sustainable Rural Livelihoods framework, the key determinants of land allocation and soil investment were found to be household productive capacity, the productive potential of the land, the degree of household livelihood diversification, and the farmer's capacity to recognise opportunities, prioritise and enact entitlement. The household's endowments were dynamic and spatially differentiated. The diversity of livelihood situation, knowledge, experience, and perceptions of power and identity created many different routes of livelihood response, and varying rates of agricultural investment. Within these multiple pathways, there were dynamic transformations between natural capital and the non-farm component of rural dwellers' livelihoods.