Cider and/or beer lees has normally either been used as low cost animal feed or been disposed of at great cost. A higher value use for the yeast was therefore sought. This has been developed with the use of environmentally friendly subcritical water extraction. Results have shown that the extract contains anti-oxidant activity using two separate anti-oxidant assays, with a large improvement in activity above a process temperature of 200 °C. This is due in large part to an increase in the concentration of phenolic compounds in the extract. As a result of this, a refined extract was produced using supercritical CO2 that improved anti-oxidant activity compared to the crude extract. The anti-oxidant activity of the 200°C and refined extract has also been demonstrated using the comet assay in cells with the performance of the extracts being comparable to that of Trolox. The rheological stability of a number of cosmetic formulations incorporating the extract has also been tested with 2 of the 4 formulations being stable. However, colour change issues have been observed with all four formulations tested. Overall, a novel and biologically effective extract has been produced using data from anti-oxidant assays to improve activity of the extract.

Switchable oligopeptides, able to expose of conceal biomolecules on a surface, upon the application of an electrical potential, represent a versatile tool for the development of novel devices, presenting potential biomedical applications. Recently, several studies have demonstrated the applicability of smart devices for the control of protein binding and cellular response. In this work; a detailed analysis of the steric requirements necessary to develop a mixed oligopeptide Self-Assembled Monolayer (SAM) presenting an optimum switching ability will be described. The influence of both the SAM components surface ratio and the switching unit length on the mixed SAMs switching performance will be investigated. The findings of this investigation will be used to develop, for the first time, a platform, based on electrically switchable oligopeptides, able to control the interaction between an antigen and its relative antibody. The influence of the biological medium on the oligopeptide switching ability will also be investigated. Finally, an orthogonal functionalisation strategy, will be investigated in detail, together with a new platform able to promote human sperm cells adhesion. The results of this research thesis will also represent the first building blocks towards the development of glass-gold rnicropattemed surfaces able to control the calcium signalling in human sperm cells, presenting potential applications in the improvement of in-vitro fertilisation (NF) treatments success rates.

The aim of the present work was to study the effects of molecular interactions between proteins upon foam quality in batch and continuous operations, and to investigate foam fractionation as a method of protein recovery from real biological feedstocks. Foam stability studies of model protein solutions acted as engineering indicators and highlighted the importance of electrostatic interactions between basic (lysozyme and cytochrome-c) and acidic proteins (BSA) upon foamability and foam stability. Batch and continuous foam operations were employed in the study of electrostatic interactions between BSA and lysozyme and their effects upon foam quality. Batch foam production at pH 8.0 strongly demonstrated the importance of molecular stoichiometry upon individual protein partition into foam. Maximal lysozyme recovery was achieved at equimolar conditions and coincided with minimal fractionation between the two proteins. Continuous foaming demonstrated that foam positive proteins such as BSA (collector) can function as mobile ion-exchangers for poor foaming agents such as lysozyme (colligend). Experimentation with real biological systems such as brewer's yeast extract indicated that complex protein systems appear to behave like single protein solutions in terms of the effects of operating parameters upon foam performance. Such behaviour was confirmed by preliminary studies with bovine heart muscle homogenate. "Dry" foams, in continuous foam processing of brewer's yeast extract, were associated with dilute feedstocks, low gas flowrate and prolonged liquid residence times. They were characterised by high protein enrichment, low recovery, enhanced protein fractionation from RNA, but suffered extensive protein precipitation. Studies of dynamic changes in foam bubbles showed that such phenomena are associated with extensive coalescence. It was concluded that, although single protein model systems can offer valuable information on foam fractionation, direct comparisons with real biological solutions should be treated with care. A need for further study on the role of protein interactions upon foaming was also identified. Finally, the currently held view of rejecting foaming as a source of protein precipitation should be reviewed and advancements in foam fractionation as a preliminary step in downstream processing should employ the development of semi-empirical predictive models.

Calcium phosphates (CaPs) have been used extensively as bone replacement materials, substrates for drug release and transfection agents because of their non-cytotoxic nature and chemical similarity to the mineral component of human bone. However, biomolecule attachment to CaPs usually rely upon adsorption, which can lead to inconsistent coverage and variable release, and the fate of CaPs upon cellular internalisation is not fully understood. The difficulty in tracking the particles can be related to the visual similarity to granulation within the cells. This thesis sought to functionalise the surface of CaP particles to enable the engraftment of biomolecules onto the particle surface and the formation of a cross-linked matrix. The engraftment of a thiol-reactive fluorescent dye gave visual confirmation that molecules can be bound to the surface and enabled silicon-substituted hydroxyapatite (SiHA) particle tracking within MC3T3 cells. Volume and size distribution analysis suggested that internalised particles larger than 1μm, but not encapsulated within lysosomes, correlated with observations of cell death. The method was expanded for other CaPs and demonstrated through engraftment of a novel antimicrobial peptide, which was shown to be more effective at preventing biofilm formation than surface adsorbed peptide, and the fabrication of a new organic/inorganic composite.

Cell therapy has recently gained much attention as a novel treatment method for a range of diseases. Many early examples of mesenchymal stem cell use have focussed on infusion of a cell population and rely on the cells locating to the area of tissue damage. The development of implantable materials in the form of microcarriers to deliver cell populations to the site of injury could help enhance efficacy of treatment. Such carriers may also be used to expand cell populations \(in\) \(vitro\). In this thesis, a range of cell culture beads have been formulated using calcium phosphate ceramics, with and without the addition of a hydrogel such as gellan gum. The processing of the calcium phosphate (brushite) cement beads was shown to be critical to cell attachment, with the use of a crystallisation inhibitor in the formulation causing cell detachment. By conditioning the beads post manufacture or by using a process of granulation of brushite crystals, it was possible to generate beads that enable attachment and proliferation of the cells: a ~34 fold increase in the case of post treated beads and ~6 fold in the case of granulated beads. It was also shown that modification of gellan gum with nanoscale HA (nHA) at a concentration of 50 wt% allowed the control of mechanical properties by increasing yield strength and bulk modulus by four- and nine fold, respectively. Finally, it was shown that both ceramic and ceramic-hydrogel beads were conducive to bone formation when culturing MC3T3 pre-osteoblast cells in static and dynamic conditions, respectively.

In the past decades, the study of nanotechnology has brought in tremendous progress to the development of polymer electrolyte fuel cells (PEFC) and many advanced catalyst approaches have been developed. However, many of these still remain at ‘test-tube’ level and have not been implemented in practical fuel cells. The concerns about the gap between the pure material research and fuel cells are increasing, and a study focusing on the electrode structures is required to help address this issue. In this thesis, the in-situ growing process of one-dimensional (1D) Pt-based nanostructures on gas diffusion layers (GDLs) was systematically studied to help understand the structure-property relationship of the gas diffusion electrodes (GDEs). The crystal nucleation and growth, coupled with the distribution of the produced nanostructures were investigated based on the corresponding GDE performance in PEFCs. The influence of the in-situ growing temperature, the hybridizing Pd metal and the structures of the GDL itself were comprehensively investigated for a further understanding of the in-situ nanowire growing process. This work demonstrates that besides the intrinsic catalytic activities of the catalysts themselves, their optimal implementation in electrodes, i.e. the electrode structure, play an important role in the power performance of PEFCs than we initially expected.

Metallic nanoparticles (MNPs) are attracting increasing interest for many applications in photonics, ranging from optoelectronic devices to bioimaging and biosensing. An advantage of these systems is that their optical properties, governed by their localised surface plasmon resonance, are widely tunable via the nanoparticle shape and size, which can be controlled via e.g. colloid synthesis. In that context, it is important to develop accurate experimental methods able to correlate the size and shape of an individual single MNP, measured with nanometric precision, with its individual optical properties. In this thesis, three different MNP systems, namely i) commercially-available Ag nanocubes of 75 nm edge; ii) Ag tetrahedra, bi-tetrahedra and decahedra in the 25 - 50 nm size range which was fabricated in-house using a plasmon-mediated photochemistry method; iii) Ag nanodimers was fabricated in-house via controlled self-assembly of polymer linkers onto commercial nominally spherical Ag nanoparticles of 40 nm diameter. Beyond fabrication, a substantial part of the work reported in this thesis describes the experimental protocol for correlative optical and transmission electron microscopy, which was developed and optimised, comprising reproducible deposition of these silver nanoparticles onto TEM grids, their optical characterisation via polarisation-resolved high-resolution dark-field and extinction micro-spectroscopy, and subsequent high-resolution TEM of the same particle. As proof-of-concept, the same Ag nanocubes of 75 nm edge were characterised optically in different dielectric environments, using solvents of different refractive index n; specifically, anisole (n=1.52), water (n=1.33), and air (n=1). The MNP scattering and extinction cross-section was determined in absolute units using an in-house developed quantitative measurement protocol, and the results are compared with numerical simulations using the measured geometry. These studies pave the way toward an in depth understanding of the relationship between geometrical and optical properties of MNPs of non-trivial shapes, which in turn have the potential to be exploited in innovative bioimaging and biosensing platforms.

In investment casting, the removal of wax from the shell is a critical step which may cause shell failure. It would be advantageous to predict the stress development during de-waxing process with computer simulation. The process was simulated with the consideration of two aspects: (i) The thermo-physical data required to model the shell and wax behaviour in the autoclave environment and (ii) A simulation capable of capturing the interaction between shell, wax and the autoclave environment. Data on mechanical properties, thermal properties, permeability, rheology, thermal expansion and density was gathered for wax and shell as appropriate. Flow-3D was used to simulate the de-wax process such that the shell and wax can be simultaneously modelled. It was shown that the Von misses stress exceeded the expected critical failure stress at certain nodes after steam was introduced to the system. Waxes with higher viscosity were predicted to reach the critical stress sooner. The simulation showed that for the selected drainage orifice sizes that was no or little difference in the time taken to reach the critical stress. Wax compressibility which was considered to represent shell permeability was predicted to have a large effect on shell cracking prediction. In general, the statistics of failure in validation test limited the conclusions that could be drawn. Waxes predicted to show differences in cracking and drainage with increasing orifice size did so in the experiment. The simulated drainage times were greater than determined experimentally by around 380s and this requires further investigation.

Freeze drying is a widely-used dehydration technique in food and pharmaceutical industry, involves water crystallisation (freezing) and ice sublimation during the process. The purpose of the study is to enable the initial concentration of solutions that are used in freezing and freeze drying processes to be increased, as an approach to reduce the energy consumption of the process. Spontaneous crystallisation from both sucrose solutions and coffee solutions was studied by DSC, XRD and cryo-SEM, and results showed that increasing solid concentration (up to 70%) significantly delayed the water crystallisation, shown as lower crystallisation temperature and less or even no ice crystal formation. A method was developed to induce water crystallisation by adding already formed ice seeds to water, which allowed the study of ice crystal growth rate at controllable conditions. The method combined the use of a temperature controlled stage and an optical microscope, and the effects of solid concentration (up to 60%), temperature, viscosity, solute type, and air bubbles on crystal growth were investigated. Freeze drying high concentration sucrose (up to 60%) showed significant volume expansion (collapse), and methods to reduce the collapse were tried by modifying the formulation (adding high molecular weight gum Arabic) or freeze drying cycles (reducing heating rate between primary and secondary drying). Results showed that the up to 30% concentration of sucrose solution can be dried without volume expansion with modified freeze drying process.

The aim of this thesis is to develop a comprehensive mathematical model with detailed kinetics of Fischer-Tropsch (FT) and water gas shift reactions (WGS) to predict the results obtained from experimental study of cobalt-based FT synthesis conducted in a fixed-bed reactor. The kinetics’ parameters were evaluated for developed kinetics’ models, using an advanced optimization technique. Physical and statistical consistencies of the kinetics’ parameters were evaluated by various statistical methods. The developed model based on combination of alkyl/alkenyl mechanism (for production of n-paraffins and α-olefins) along with formate mechanism for WGS reaction provided the most accurate predictions. Model validation was conducted subsequent to completion of model calibration and estimation of proper kinetic parameters to ensure that model provides robust and realistic assessment of all parameters. Parametric studies were performed to investigate effects of operating conditions on the catalytic performance of FT synthesis with respect to products’ selectivities and syngas conversion. The operating conditions that have most significant effects were included in multi-objective optimization process using non-dominated sorting genetic algorithm to optimize selectivities and conversion. Pareto-front solutions can be used as dynamic database depending on specific requirement. Different operating condition can be selected from such database which privileges optimization of particular output.