This thesis presents the results of research into the use of Recycled Organic Wastes (ROWs) as soil amendments to aid the growth of energy crops on brownfield sites in the UK. In order to divert biodegradable waste from landfills, food waste is source segregated by households or is mechanically separated from mixed Municipal Solid Waste (MSW) before being biologically decomposed to form stable ROWs. The source of waste stream influences the future market and use of ROWs. Three different ROWs were characterised to assess the effect of the initial waste stream and the influence of aerobic or anaerobic biodegradation processes on the final organic products. Growth trials were conducted to assess the use of ROWs as nutrient sources for three fast growing tree species, S.viminalis, E. nitens and P. tomentosa. Preliminary growth trials found that high total dissolved solids were associated with some ROWs were detrimental to plant health and survival rates. Further growth trials identified the optimum total nitrogen application rate of ROWs when mixed with Kettering Loam, a clay loam. Analysis of leachate collected from the pot trials identified changes in quantities of heavy metal and nitrogen leaching during the growth trials and allowed comparison to water quality limits for aquatic life to assess the risk to the wider environment. Column growth trials assessed the effect of saturated and unsaturated conditions on a specific ROW known as Compost- Like Output derived from MSW, the impact on plant growth and the effect on leachate composition. Saturated conditions were detrimental to E. nitens, whereas S. viminalis adapted to saturated conditions with greater biomass production compared to the unsaturated columns. A reducing environment resulted in differences in heavy metal leaching and nitrogen forms compared to the unsaturated columns. The use of ROWs on brownfield sites can improve the overall soil quality while providing sufficient nutrients to improve biomass yields of energy crops. However the source of ROWs and biological treatment methods can influence the characteristics and future use of the ROWs. CLO derived from MSW had significantly higher heavy metal concentrations than source segregated material. Higher concentrations of heavy metal, particularly of copper, zinc and lead were identified within the fines (< 1 mm) of MSW derived CLO. Leachate analysis from the optimum and column growth trials identified changes within the pore water chemistry, which also influenced the mobility of heavy metals. The application of ROWs to brownfield sites has the potential to release soluble nitrogen forms and heavy metals into the wider environment; however application to contained sites or lower applications will reduce the risk.

This thesis reviews the use of sulphur hexafluoride (SF6) as an insulating medium in the electrical power industry and quantifies the potential global warming effects associated with its continued use. A mixture of Trifluoroiodomethane (CF3I) and carbon dioxide (CO2) is suggested as a potential alternative to SF6, and its insulation properties are examined. Pressure mixture ratios of 10%:90%, 20%:80% and 30%:70% CF3I-CO2 are used in the laboratory test programme. A test rig has been developed to safely fill and recover gas mixtures of CF3I-CO2 in switchgear. Practical medium voltage (MV) switch disconnectors and ring main units are used to test the insulation properties of CF3I-CO2 gas mixtures and compared with SF6 using standard lightning impulses (1.2/50 μs). The experimental mixture ratios are used to identify how the insulation strength varies depending on the content of CF3I used. The switchgear is filled to its normal and minimum operating pressure to observe the reduction in insulation performance of the gas mixtures when the pressure is reduced. The insulation strength is measured using the 50% breakdown voltages (U50) and withstand strengths of each gas mixture in accordance with international standards. The effective ionisation coefficients of various CF3I-CO2 gas mixtures are calculated. This process identified the estimated critical reduced electric field strengths of several CF3I-CO2 gas mixtures. Furthermore, electric field simulations utilised the effective ionisation coefficient functions and the contact geometry of a switch disconnector to predict the likelihood of a flashover occurring for various CF3I-CO2 gas mixtures. This investigation shows that CF3I-CO2 can successfully be used to insulate practical MV switchgear but is dependent on equipment design and operating pressure. It has previously been indicated that by-products of CF3I make it unsuitable to interrupt high current. Therefore, it is suggested in this study that CF3I-CO2 gas mixtures can be adopted to insulate equipment such as vacuum circuit breakers.

The firm adhesion of flavouring particles onto snack surfaces during coating processes is a major concern in the snack production industry. Detachment of flavouring powders from products during handling and production stages can lead to poor appearance and reduced taste of the product as well as substantial financial losses for the industry, in terms of variable flavour performance and extended cleaning down time of fugitive particle build-up on process equipment. Understanding the adhesion strength of applied bulk particulates used for flavouring formulations will help analysts to evaluate the efficiency of coating processes and potentially enable them to assess the adhesion strength of newly formulated flavouring powder prior to commitment to full scale plant trials. Meeting this object has required the development of an over-arching review of the adhesion mechanisms as a primary step. Based on this overview to the work of previous researchers, technological gaps and promising techniques have been identified for further research and development. A prototype of a novel adhesion tester called an Impact Adhesion Tester (IAT) has been designed and constructed. The development of the overall tester design is presented, and details of its parts and the resulting tester are discussed. The IAT and its experimental procedure were primarily designed and implemented for use in the snack industry, in particular, for the measurement and evaluation of the key factors affecting the adhesion behaviour of flavour powder onto snack surfaces qualitatively and quantitatively. This measurement can indicate the percent flavour powder loss within production stages (from coating to packing) and in package. The instrument has been evaluated using different materials and substrates subjected to different coating conditions such as rotational speed of the drum, retention time in drum, the amount of surface oil and the amount of powder applied. By plotting the detachment versus impact force, the difference has been obtained between adhesion strength of different flavouring powders (which is a strong function of particle size, particle shape, particle density and surface oil content of the snack). In addition to the above work, ultra-centrifuge method was used as a reference for comparison. The research work conducted using IAT on flavouring powders has proved the importance of particle adhesion strength and that the particle adhesion strength can reflect the changes in particle loss, based on particle characteristics as well as process conditions during snack production. It proved that bench size IAT would be a useful tester to measure adhesion strength of particles. The results obtained from experiments have confirmed that the tester may be able to usefully determine the variations between different powder materials. However the tester needs to be further evaluated by industrialists and researchers before possible use or commercialisation.

Clostridium sporogenes was previously shown to be an extraordinary source for unusual reductases. It can catalyze reduction of wide a range of substrates such as nitroalkenes, enoates and nitro compounds, and can be used to generate chiral products. In preliminary studies, the ClosTron gene knock-out system for Clostridia was used to inactivate the fldZ gene assumed to encode the enzyme responsible for reduction of cinnamic acid in the reductive branch of L-phenylalanine fermentation via the Stickland reaction. Biotransformations with the fldZ mutant showed that C. sporogenes possesses multiple enzymatic activities, reducing enoates, β,β- and α,β-disubstituted nitroalkenes with different yields and enantioselectivities. The fldZ reductase was found to be responsible for reduction of cinnamic acid, (E)-1-nitro-2-phenylpropene, (E)-2-nitro-1-phenylpropene and β-nitrostyrene. However, the mutant could still reduce (E)-2-nitro-1-phenylpropene, β-nitrostyrene and cinnamic acid confirming the presence of other C=C double bond reductases in C. sporogenes. The analysis of the C. sporogenes genome sequence allowed identification of two hypothetical genes encoding proteins with homology to flavin-containing C=C double bond reductases, fldZ 2-enoate reductase and OYE-like reductase, which were subsequently cloned, overexpressed in E. coli under anaerobic conditions and tested for reduction of unsaturated compounds. The activity tests showed that fldZ possesses a narrow substrate range and can reduce only aromatic enoates such as cinnamic acid or p-coumaric acid. FldZ also reduced (E)-1-nitro-2-phenylpropene and (E)¬-2-nitro-1-phenylpropene with excellent and poor enantioselectivities (>99% and 16% respectively). On the other hand, the OYE-like reductase did not show activity towards unsaturated substrates in the activity assays and the substrate range of this reductase is unknown. Growth experiments comparing wild type C. sporogenes and the mutant in complex and minimal media showed that the fldZ reductase in not involved in the L-phenylalanine fermentation. Further analysis of the C. sporogenes genome resulted in identification of a novel reductase that might be involved in reduction of cinnamoyl-CoA to 3-phenylpropionyl-CoA in the Stickland reaction. Biocatalytic reduction of aromatic nitro compounds to amines can be used as alternative to chemo-reductive routes in preparation of pharmaceutical and agrochemical products. Protein extracts of C. sporogenes were found to reduce aromatic nitro compounds with different yields depending on the substrate structure and electron donor used in the reaction. The genome of C. sporogenes was screened and that allowed identification of six genes encoding hypothetical nitroreductases, which were subsequently overexpressed in E. coli. However, biotransformations using the recombinant nitroreductases did not show amine product formation. A novel Nylon 6 biosynthesis pathway was designed starting from biorenewable feedstocks. The crucial step in this pathway, reductive cleavage of pipecolic acid to 6-aminocaproic acid was proposed to be catalysed by C. sporogenes D-proline reductase. Thus, the activity of this enzyme was tested towards L- and D-pipecolic acid. Biotransformations showed that pipecolic acid was not accepted as a substrate. In the future, the idea of using D-proline reductase for Nylon biosynthesis may be exploited by improving the reductase activity using protein engineering techniques.

The aim of this project was to develop and compare microwave at 2.45 GHz and conventional heating processes to produce low molecular weight methyl methacrylate oligomers. The required level of conversion for this process to be successful was 40 %. Batch and flow processes were investigated for both heating methods, and conversions of up to 70 % in batch and 55 % in flow were achieved. A large number of publications conclude that microwave heating can lead to significant improvements in conversion, rate and product quality when compared to conventionally heated reactions. In many cases this has been attributed to a non-specific thermal effect due to material interactions with the electric field component of the microwave. In many cases these conclusions stem from inaccurate temperature measurement in a microwave environment, and comparisons with conventional heating being carried out under different conditions. In this work a robust methodology was developed to compare microwave and conventional heating for oligomer production. Initial work was carried out at 30-50 cm³ using a CEM Discover SP (300 W) microwave, a conventionally heated stirred oil bath and a single mode cavity. Investigation into the effects of temperature, heating rate and reaction time on conversion were carried out, and it was found that the target material could be produced to 70% conversion in less than 5 minutes. From the understanding gained using small scale batch reactions a set of design requirements were produced for larger scale flow systems using microwave and conventional heating, and these systems were constructed as part of this project. This apparatus allowed for repeatable production of the target material at flow rates of up to 36 kg/hour when operated using a 2 kW microwave generator with automated tuning. Conventional comparisons were carried out at in flow with the use of apparatus of the same physical geometry under the same conditions. This is the first work published to carry out direct comparisons between conventionally heated and microwave reactions under the same conditions. It was found that at all scales and under all the conditions investigated that there were no quantifiable benefits in conversion or product quality offered by the use of microwave heating. It was concluded that such benefits concluded elsewhere are likely to result from poor control and rigour in experimental comparisons.

A new process of combining gas injection with compression moulding was developed and studied in this research work. The process is called Gas Assisted Compression Moulding (or GasComp). The principle is based on the injection of nitrogen gas during a conventional compression moulding cycle. The flow of the material due to the compressive force of the press is assisted by the injection of gas into the centre of the molten material. The gas assists in the flow by coring out the material, reducing the weight by up to 45 percent and increasing the dimensional stability of the component. Novel glass matt thermoplastic mould tools were designed and developed during the course of the research program for use with the process. These designs were of a flash compression mould tool design with a horizontal clamping face, rather than the conventional positive plug compression mould tool with a vertical shear edge. This created a fixed volume mould tool, which when used in conjunction with a short shot of material, would allow the gas to flow the material to fill the remaining volume. Several materials were investigated for their suitability with the process. Their characterisation showed that they contained different glass fibre contents and architectures. A material with a short, dispersed glass fibre content of 11 percent proved to consistently contain a significant gas cavity. The glass architecture proved to be the most significant contributing factor in the creation of a successful gas cavity. The most significant processing parameter in the creation of a large volume cavity proved to be the gas injection delay time. The gas pressure and gas ramp time affected the cavity shape, length and extent of gas fingering. The shrinkage was reduced in the presence of a gas cavity, along with the visible reduction of sink marks. The presence of other moulding features, such as hesitation marks, gas packing and the change in fibre orientation were also discussed.

A novel adsorption cycle in which enhanced heat transfer between the adsorbent and external heat sinks and sources is achieved by forced convection of refrigerant gas through the adsorbent bed is presented This cycle is further developed by the use of inert beds to store the heat of desorption and sensible heat between phases. The performance and utility of such a cycle will depend on the heat transfer coefficients and pressure drops that result when the refrigerant gas is circulated through the beds The heat transfer and pressure drop characteristics of a bed of granular active carbon were investigated using argon, carbon dioxide and ammonia. Equipment was designed and built to pass a stream of gas through a bed at a controlled rate, pressure and temperature. The pressure drop characteristic was found to conform to Ergun equation and the constants for the application of that relation to a commonly available granular active carbon established. A mathematical model based on a finite difference technique was created and used to predict the progress of a temperature front in the bed and derive the heat transfer characteristics from experimental data. Heat transfer coefficients measured with argon and ammonia appeared inconsistent with each other and after investigations of the data and comparison with established correlations were made it was concluded that carbon during the argon experiments had been contaminated. The heat transfer results with ammonia and carbon were compared with a modified version of the Colburn analogy between heat transfer and pressure loss. A correlation between the Nusselt number and Reynolds number for design purposes was established.

Electron paramagnetic resonance (EPR) has been used to study point defects in synthetic single crystal diamond. Newly observed defects are reported in high pressure high temperature (HPHT) and chemical vapour deposition (CVD) diamond. HPHT diamond doped with 15N has been used to investigate the g = 2 region of the EPR spectrum which is obscured when natural isotopic abundances are present. Two previously unreported defects labelled WAR9 and WAR10 are reported. The EPR data has been shown to be consistent with the neutral nitrogen interstitial, N0 I (WAR9), and neutral nitrogen di-interstitial, NI-I001 (WAR10), defects respectively. Two further defects observed in CVD diamond are reported here. The first labelled WAR2 is preferentially aligned with the direction of growth, [001]. The EPR data is consistent with a (V-(CH)-V)0 structure although theoretical studies suggest that this structure is unstable at CVD growth temperatures. Growth mechanisms are suggested that would account for the observed preferential alignment. The second defect labelled WAR5, has been observed exclusively in samples grown using an experimental CVD chemistry containing oxygen. The EPR data is consistent with the OV0 defect, although no confirming 17O hyperfine structure has been observed. 13C hyperfine data is also reported for the KUL1/VnH− defect (n = 1 or 2) but the new data is not sufficient to conclusively discount either the n = 1 or n = 2 models suggested for this defect. Changes in defect concentrations in CVD diamond with thermal and illumination treatments has been investigated. Experimental data has indicated the presence of an unseen trap, common to CVD diamond, with concentrations comparable to that of N0S, and levels in the band-gap 0.5{1.2 eV above the top of the valence band. The difficult quantification of sub part per billion defect concentrations, as observed in electronic grade material, is tackled with the use of rapid passage EPR. It is shown that with this technique it is possible to detect concentrations of single nitrogen in diamond at tens of parts per trillion, close to a factor of 100 improvement on the currently used slow passage EPR.

The chemical senses of taste and smell are the two least well understood of our senses. Recent advances in our understanding of the genetic and molecular mechanisms have led to increasing interest in olfaction and gustation. Amongst the practical applications of fragrances and flavours are commercial consumer products. The primary source for inspiration for these is nature and the work discussed in this thesis addresses methods for isolating selected aroma and taste molecules from natural sources, for use as new ingredients in food and fragrance applications. The methods are designed to deal with the challenges of isolating and identifying species present at very low concentrations (as low as parts per trillion), of unstable nature and with the desire to target specific functional groups. Carbonyl and thiol compounds have been selected for trapping due to their interesting fragrance and flavour characteristics respectively. A portable reactive trap has been designed, built, and tested to isolate aldehyde (or ketone) compounds from the headspace of living plants. The trap uses the derivatising reagent, 0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride coated on to a solid sorbent, Tenax TA'-"'. Reagents with immobilised reactive groups capable of selective reacting with thiol compounds have been investigated and the proof of principle has been illustrated for three different methods. The nature identical status of the cooling compound, L-monomenthyl succinate, has been demonstrated by using highly sensitive and selective analytical techniques to identify this compound in the berries and leaves of plant Lycium barbarum. A preparative liquid chromatography system was used to simplify plant extracts which were subsequently analysed using nano liquid chromatography-electrospray ionisation-tandem mass spectrometry (nLC-ESI-MS/MS). This system could be applied to the analysis of other natural source extracts.

The results from EPR studies of CVD diamond which was intentionally silicon doped with isotopes in natural abundance or isotopically enriched are reported. The observation of hyperfine satellites arising due to the presence of 29Si has provided definitive evidence for the involvement of silicon in two EPR centres in diamond which were previously suspected to involve silicon: KUL1 and KUL3. KUL1 is unambiguously identified as the neutral silicon split vacancy defect (V-Si-V)0, whilst KUL3 is shown to be (V-Si-V)0 decorated with a hydrogen atom. Data have also revealed that (V-Si-V)0 is preferentially oriented in samples grown on {110} substrates. The negative nitrogen-vacancy centre (NV‑) has been investigated. Published parameters for the nitrogen hyperfine interaction produce an unsatisfactory fit to the experimental spectra and hence these parameters are redetermined. Optically-excited EPR has been used to estimate the degree of spin polarisation of the NV-ground state and the increase in signal intensity with illumination has permitted the interaction between the unpaired electron and neighbouring 13C atoms to be studied. Two sets of 13C hyperfine satellites have been identified, which account for ~100% of the unpaired electron probability density. Despite the predictions that the neutral charge state of NV should have an S = ½ ground state, this charge state has not previously been detected by EPR. Optically excited EPR measurements reveal a trigonal nitrogen containing defect in diamond with an excited state populated via optical excitation. Analysis of the spin-Hamiltonian parameters and the wavelength dependence of the optical excitation leads to assignment of this state to the 4A2 excited state of NV0.