This work investigated the suitability of thin film, single and multi-layered coatings, by a Physical Vapour Deposition (PVD) process for polymer electrolyte membrane fuel cell bipolar plates. Due to the multifunctional nature of this particular component a comprehensive approach was used where several key properties were examined for coatings including: ZrN, TiN, CrN, Graphit-iC™, CrN+C, TiN+C and Au. Chemical etching and surface roughness were found to influence the Interfacial Contact Resistance (ICR) of the substrate; however, any observed effect was negated with the addition of a conductive coating. CrN+C and TiN+C multi-layer coatings showed a striking reduction in the ICR compared with the nitride only equivalents. The suitability of pre-coated PVD coatings for serial production via stamping was assessed in collaboration with an industrial partner. The coating durability was found to be influenced by several factors including coating type, thicknesses and position on stamped plate. The multi-layered TiN+C coating was found to noticeably improve the stampability compared to the TiN only coating. The corrosion resistance of the coatings was evaluated under simplified corrosion conditions. Under these conditions TiN+C was found to have two beneficial effects, improving the free corrosion potential and the stability of the carbon topcoat under startup/shutdown potentials.

The practical feasibility and generic applicability of the direct integration in the same time frame of cell disruption by bead milling with the capture of intracellular products by fluidised bed adsorption has been demonstrated. Pilot-scale purification of the enzyme L-asparaginase from unclarified Erwinia chrysanthemi disruptates exploiting this novel approach yielded an interim product which rivalled or bettered that produced by the current commercial process employing discrete operations of alkaline lysis, centrifugal clarification and batch adsorption. In addition to improved yield and quality of product, the process time during primary stages of purification was greatly diminished. Two cation exchange adsorbents, CM HyperD LS (Biosepra/Life Technologies) and SP UpFront (custom made SP form of a prototype stainless steel/agarose matrix, UpFront Chromatography) were physically and biochemically evaluated for such direct product sequestration. Differences in performance with regard to product capacity and adsorption/desorption kinetics were demonstrated and are discussed with respect to the designof adsorbents for specific applications. In any purification of L-asparaginase (pI=8.6), product-debris interactions commonly diminish the recovery of available product. It was demonstrated herein, that immediate disruptate exposure to a fluidised bed adsorbent promoted concomitant reduction of product in the liquid phase, which clearly counter-acted the product-debris interactions to the benefit of overall product yield.

Polymer electrolyte membrane fuel cells (PEMFCs) are envisioned to replace internal combustion engines (ICEs) as vehicle power sources and to compete with conventional technologies in backup power systems, residential combined heat and power (CHP) devices and consumer electronics. However, the commercial viability is still hindered due to the cost and durability that are significantly related to the precious metal catalysts used in these cells. In the current work, two different methods towards reducing the precious metal content by the use of transition metal (Cr) with Pt as electrocatalysts for PEMFCs are reported. The commercial Pt/C catalysts layer consists of three components i.e. Pt, carbon support and Nafion ionomer. The Nafion ionomer binder does not penetrate through the microporous carbon support and thus limits the triple phase boundary region (catalytic reaction takes place at triple phase boundary), which in turn leaves a significant amount of Pt being inactive or not utilised. In the first part of this work, Nafion- stabilised Pt-Cr alloys are synthesised using a novel wet chemical synthesis. The aim of this work is to improve the triple phase boundary region with the introduction of Nafion during the synthesis and alloying with Cr that can enhance the catalytic activity. Thus, in turn improving the utilisation of the catalyst and also reducing the amount of Pt loading.

Cleaning studies were performed to remove toothpaste by fluid flow at different temperatures and velocities to mimic CIP (Cleaning-In-Place) processes on toothpaste coated coupons at laboratory scale and fully filled pipeline at pilot scale (different lengths and diameters). The cleaning time was reduced by increasing the velocity and temperature of the water, however no further time benefit was seen above 40°C. The adhesive force for different pastes calculated from micromanipulation data followed the same trend as cleaning times on the laboratory cleaning rig. This cleaning data for the different paste formulations had a logarithmic relationship with the viscosity term from the Herschel-Bulkley rheological model. Removal of toothpaste from pipes occurred by the core of the paste being removed from the centre of the pipe to leave a thin coating on the pipe wall, which was then eroded by flow. Pipes of lengths between 0.3 m and 2 m (47.7 mm diameter pipe) showed no difference in cleaning time. The rate limiting process was removal of the thin wall coating and therefore not a function of length. An inverse wall shear stress relationship with cleaning time was found to represent all the data, at all scales and under all conditions.

Silicon has been shown to be an important trace element in bone formation and metabolism, and a decrease in silicon in the mammalian diet leads to abnormal bone formation. Consequently, silicon has been incorporated into many biomaterials to enhance bone generation around implants. Despite this, the mechanism of action has still not been elucidated and a therapeutic dosage has not been determined. In this thesis, the optimum concentration of orthosilicic acid (OSA) to enable cell survival and early mineralisation has been identified. It was noted that a dosage of 5µg/ml of OSA enhanced bone nodule formation. The presence of OSA increased the expression of early osteogenic markers such as osteopontin, osteocalcin and type 1 collagen. In addition, increasing OSA concentration resulted in the development of a collagen fibril network of increasing complexity, up to supraphysiological OSA concentrations when the fibril network became fragmented. It was hypothesised that this may assist with mineral deposition. A sustained delivery system was also developed using a combination of PLGA and calcium silicate. A sustained dose of orthosilicic acid ideal for cell survival was released from the PLGA micro-particles containing calcium silicate. As well as providing a source of OSA, the presence of the alkaline degradation products of calcium silicate aided in the neutralisation of the acidic degradation products of PLGA, which might enhance cell viability in the local environment. In addition to influencing cell behaviour, the OSA was shown to have a strong interaction with alginate, modifying its properties and preventing degradation. This finding is of importance as the molecules comprising alginate bear a structural resemblance to the glycosaminoglycans that are found in the majority of tissues.

The decomposition of high-performance thermoplastic and thermoset polymers is carried out by using supercritical fluids, in conjunction with a caesium carbonate catalyst (Cs\(_2\)C0\(_3\)). Polyetheretherketone (PEEK) and its carbon fibre filled composite are used as the high-performance thermoplastic, owing to its strong chemical resistance and excellent thermal and chemical stability. 2,2-Bis[4-(glycidyloxy)phenyl]propane (BADGE) is cross-linked with 4,4' –diaminodiphenyl sulfone (DDS) to produce a high-performance thermoset resin used to investigate the decomposition of the polymer matrices used in the manufacture of carbon fibre reinforced polymers (CFRP’s). It is determined that the complete decomposition of the BADGE based thermoset resin is possible at 573 K when using a catalyst concentration ([Cs\(_2\)C0\(_3\)]) of 10 ml\(^-\)\(^1\) in 100% ethanol or propanol and a reaction time of 30 minutes, with a percentage degradation of 90 % being achieved after 45 minutes. The decomposition of PEEK at 623 K, 7 K above its melt temperature, is possible within 30 minutes when using a supercritical fluid mixture of ethanol and water ([EtOH] = 20 %v) and a Cs\(_2\)C0\(_3\) concentration of 10 mg ml\(^-\)\(^1\) decomposition of PEEK in 100 % ethanol was not observed, indicating that the decomposition reaction is hydrolysis. Conversely, the decomposition of the BADGE based thermoset resin was essentially impeded by the presence of water and is therefore one of solvolysis. Both decomposition reactions were found to be 1st order with respect to [Cs\(_2\)C0\(_3\)].

The effect of thermal behaviour and properties such as enthalpic relaxation, degree of crystallinity, development of crystallization, crystallization kinetics and melting behaviour of Co-poly (lactic acid) were studied using differential scanning calorimetry (DSC), FTIR spectroscopy and hot stage microscopy. Both glass formation and enthalpic relaxation have been measured on amorphous and partially crystalline samples produced by controlled cooling from the melt and the effect of the degree of crystallinity measured. Observation of the crystallization in thin films by hot-stage microscopy confirmed that the mechanism was that of the growth of heterogeneously nucleated disc spherulites. Both nucleation density and radial growth rates were measured but they exhibited different temperature dependence. FTIR spectroscopy has been used to study and characterize the change in structure of Co-PLA with temperature and time. Isothermal crystallization kinetics of Co-PLA was measured in the temperature range from 120 to 136 oc from these changes in the absorption of the IR bands and in particular the intensities of the crystalline and amorphous bands of the carbonyl ester group. In this way it was possible to analyse the kinetics of both primary and secondary crystallization directly from the relative crystallinity over extended periods with sufficient accuracy to test the validity of the Avrami equation.

This thesis studies the thermophysical properties and the phase change behaviour of EG-water and Salt-water based PCMs for cold storage applications, and investigates the role of adding MCNT on the thermophysical properties and the phase change processes. First, the structure of MCNT clusters is linked to the rheological behaviour of the nanofluids by fitting the experimental viscosity data to the modified K-D model. Second, the MCNT cluster information is used to predict thermal conductivity. The effective thermal conductivity of nanofluids not only relies on the particle concentration, but also depends on the particle cluster structure. The specific heat of MCNT nanofluids is decreasing proportionally with the concentration of MCNT. The supercooling degree of EG-water and salt-water based samples can be reduced by adding MCNT particles. The crystallization process of salt-water basefluid and nanofluid was observed and recorded under an optical microscope with cooling stage. Adding MCNT can promote the crystal growth rate.

Hybridoma cells were grown in dialysis perfusion culture using a stirred reactor within which a tubular membrane was suspended. Nutrient and product flows occurred by diffusion processes alone, and were both to and from the culture environment A mathematical model of the transfer and reaction allowed prediction of steady state cell and metabolite concentrations. Steady states in cell concentration were observed for a range of perfusion rates and membrane areas. However the model could not be applied to predict steady state cell concentrations between changes in the medium. The perfusate consisted of basal medium only. Serum addition to the reactor itself resulted in decreased steady state cell densities except when it relieved a glucose limitation. Antibody was accumulated to high concentrations and yields on both basal medium and serum were many times those achieved in standard batch cultures. Cell viability fell to 30-50% but product quality did not appear to be adversely affected by the low viability. Recombinant CHO-320 cells also grew successfully under dialysis conditions and produced 7-interferon. Cell concentrations and viabilities were higher than those seen with the hybridoma. The insect cell line SF9 did not grow during dialysis perfusion, but post infection with a recombinant Baculovirus permitted the yield of \(\beta\)-galactosidase to double in dialysis culture.

The periplasm of E. coli has been recognized a suitable location for the production of large quantities of many industrially important soluble recombinant proteins, and offers some important advantages over both intracellular and extracellular production. The oxidative environment of the periplasm promotes correct disulphide bonding and protein folding; there is reduced risk of proteolytic attack in the periplasm; and the periplasm accounts for <5% of total cell protein, so that selective release reduces subsequent purification demands. Despite these merits, periplasmic expression systems have not yet fulfilled their true potential, largely due to the lack of reliable general methods for efficient selective release of periplasmically expressed proteins at large-scale. The classical osmotic shock procedure, the only reliable method for releasing proteins from the periplasmic space of E. coli, is expensive and time-consuming, and thus it is not feasible at large scale. The main objective of this study has been to develop a gentle chemical permeabilisation method for selective release of periplasmically-expressed proteins from recombinant E. coli. In the first experiments, the titre, location and form of anti-lysozyme Fab D1.3 were determined during fed-batch cultivation of E. coli. It was shown that the Fab produced as both soluble and insoluble forms and released into the culture medium over the course of fed-batch fermentation. Purification of Fab D1.3 was then performed using various chromatographic methods, and the most effective target Fab purification was achieved by using sequential cation exchange – Protein G affinity chromatography route with an overall yield of 83%. Pure model proteins typically secreted to the periplasm (i.e. beta-lactamase, alpha amylase and Fab D1.3 fragment) were subsequently exposed to various chemicals, and alterations in the secondary structure of the proteins in the presence of various chemicals were investigated by high throughput circular dichroism (ht-CD) system. Chemicals such as 0.1% Triton X-100, 0.05% benzalkonium chloride (BAC), 0.1% cetyltrimethylammonium bromide (CTAB), and 2 M urea remarkably changed the secondary structure of beta-lactamase and alpha-amylase. The secondary structure of Fab D1.3 was more vulnerable to the tested chemicals. The biological activity of the target proteins in the presence of various chemicals was also measured and it was revealed that changes in the secondary structure of proteins do not necessarily cause reduction in the biological activity and vice versa. Concentrations of chemicals which did not reduce the biological activity of the proteins were eventually examined in subsequent periplasmic release experiments using recombinant E. coli strains producing the same target proteins, and the performance of various chemical permeabilisers were evaluated by comparing to classical osmotic shock and mechanical cell disruption. It was demonstrated that low concentrations of chemicals such as sodium deoxycholate (DOC) and/or chelating agents, isoamyl alcohol released the periplasmic proteins as efficient as or more efficient (up to 168%) than osmotic shock treatments. It was also proved that chemicals could increase the periplasmic release efficiency when they used in combinations. For instance, 1 M EDTA in combination with detergents could increase the periplasmic release of beta-lactamase and Fab D1.3 up to 80% and 130%, respectively. Such synergetic effect for release of alpha-amylase and Fab D1.3 was also observed when 1% solvents (hexane, xylene, benzene, toluene, and isoamyl alcohol) were combined with detergents such as 0.025% DOC, 0.01% CTAB and 0.1% Triton X-100.