A previous study revealed Cs_2TiNb_6O_1_8 to be the major Cs-containing phase after hot isostatic pressing Cs-loaded IONSIV (a commercial exchanger) which demonstrated excellent wasteform properties. Both experimental and theoretical studies have been carried out in order to assess if Cs_2TiNb_6O_1_8 is able to retain ^1^3^7Ba^2^+, the transmutation product of ^1^3^7Cs^+. A series of samples with different charge compensation mechanisms have been synthesised including Cs_2_-_xBa_xTi^(^4^+^)_1_+_xNb^(^5^+^)_6_-_xO_1_8, Cs_2_-_xBa_xTi^(^3^+^)_xTi^(^4^+^)_1_-_xNb_6O_1_8 and Cs_2_-_xBa_xTiNb^(^4^+^)_xNb^(^5^+^)_6_-_xO_1_8. Analysis suggested that Ba incorporation was not successful because of the identification of Ba impurities in the X-ray diffraction patterns. A series of atomistic simulations have also been performed to support the experimental work, using the General Utility Lattice Program code which suggested that Ba incorporation is not energetically favourable. Sr-loaded IOSNIV has also been thermally converted via calcination (in air) and hot isostatic pressing. The removal and immobilisation of Sr is an important process on account of ^9^0Sr being one of the more problematic radionuclides produced from the fission process. Both thermal conversion methods produced crystalline phase assembles which were analysed by X-ray diffraction, X-ray fluorescence and microscopy studies. The HIPed materials performed well in aqueous durability tests, suggesting these wasteforms will be suitable for final disposal in a geological disposal facility.

Urban demand has increased the need to redevelop contaminated land. New legislation for land management has actively discouraged previously acceptable dig and dump practices. This has encouraged in-situ remediation approaches, for which stabilisation / solidification (S/S) is particularly suitable for treating metal contamination. However, concerns over long-term effectiveness and durability of S/S needs to addressed, because contamination is contained but not removed. This requires effective chemical assessments to inform design. This study aims to design a suitable method for assessing S/S effectiveness, using a holistic risk based approach, for use during performance based S/S design. The processes that induce containment were evaluated, by assessing the solubility controlling mechanisms, and undertaking geochemical speciation modelling, to determine solubility controlling minerals. These findings can be used at the design stage to engineer S/S application to particular sites, and ensure long-term performance with minimal risk. Evaluations for structural master species (Al, Si, and Ca) and contaminants (Zn\(^2\)\(^+\), Cr\(^3\)\(^+\)) in cement stabilised contaminated kaolin were undertaken. The influences of common soil components (Humic acid and sodium sulphate), and increasing hydration durations were also assessed, to inform containment effectiveness and chemical durability. Findings showed that the assessment method was suitable for chemical characterisation of stabilised matrices, as a tool for informing design and application.

This hypothesis driven research investigated the removal of Cu, Fe, Zn and Mn from synthetic metal solutions and real Acid Mine Drainage (AMD) from Wheal Jane mine in West Cornwall UK, employing waste gas sludge (BOS sludge) which is an end waste reside generated from steel production. Batch experiments showed the efficiency and adsorption rates increased with reduction in BOS sludge particle size, lower in initial metal concentration, increase in BOS sludge dosage, an increase in initial pH and increase in agitation speed. Fitting of the Langmuir isotherm model to experimental data gave a good fit with correlation coefficients R\(^2\)≥0.99 and the selectivity series of BOS sludge was: Cu\(^2\)\(^+\)>Fe\(^3\)\(^+\)>Zn\(^2\)\(^+\)>Mn\(^2\)\(^+\). For single and multiadsorbate systems, a Pseudo second order model was the most appropriate theory to satisfactorily describe experimental data and the rate limiting step for this process was chemisorption. Adsorption was spontaneous and high pH promoted adsorption possibly by precipitation and/or ion exchange processes which had taken place between the exchangeable cations present in BOS and solutions. Results from the treatment of real and synthetic AMD solutions revealed that BOS sludge worked well and hence BOS sludge as a novel low cost material could be used as a sustainable sorbent in AMD treatment technologies.

Stimuli-responsive surfaces that can regulate specific biomolecular interactions are enabling novel functionalities and new device designs for a variety of biological and medical applications. In this study two different mixed self-assembled monolayers (SAMs) were used to regulate biomolecular and cellular interactions under complex biological conditions. The first part of this study was based on a well-defined biotinylated mixed SAM with an ethylene glycol group that prevented non-specific binding and used an electrical stimulus to allow control over biomolecular interactions under complex biological matrixes. This SAM system, based on switchable oligopeptides, can be dynamically modulated by an electrical potential under different commonly used biological media, ranging from Dulbecco's Modified Eagle Medium (DMEM) to DMEM supplemented with fetal bovine serum (FBS) and zwitterionic buffering agents such as HEPES. The second study involved electrically switchable mixed SAMs that were shown to be capable of exposing and concealing the RGD cell adhesion motif, to dynamically regulate the adhesion of immune macrophage cells under complex biological conditions. Macrophage cell adhesion to biomaterial surfaces plays a key role in mediating immune response to foreign materials. This system is one of the first examples of a material surface system that can control macrophage cell adhesion on demand. Hence, this study will be useful in developing more realistic dynamic extracellular matrix models and is certainly applicable in a wide variety of biological and medical applications.

The combustion and emissions performance of fuel blends in modern combustion systems has been investigated with the intention of reducing emissions, improving efficiency and assessing the suitability of future automotive fuels. The combustion systems used in this study include Homogeneous Charge Compression Ignition (HCCI) and Direct Injection Spark Ignition (DISI). By adding a small quantity (10%) of diesel to gasoline, the HCCI combustion of this ‗Dieseline‘ mixture shows a 4% increase in the maximum and a 16% reduction in the minimum loads (IMEP) achievable. The NOX emissions are reduced, with greater than 30% savings seen for high engine loads. The addition of bio-fuels (ethanol and 2,5 di-methylfuran) to gasoline in HCCI combustion resulted in reduced ignitability giving rise to a 0.25 bar IMEP reduction of the maximum load. A 70% increase in NOX emissions is seen at an engine load of 3.5 bar IMEP. The addition of ethanol and to a lesser extent 2,5 di-methylfuran (DMF) to gasoline in DISI combustion shows increased combustion efficiency. The NOX emissions are reduced with ethanol, but are increased with the addition of DMF. At wide open throttle the bio-fuels show up to a 3 percentage point increase in efficiency through the use of more favourable spark timings brought about by the increased octane ratings and enthalpies of vaporisation. The PM emissions from DISI combustion can be reduced by up to 58% (mass) with the addition of ethanol. The soluble organic fraction forms a significant part of the total PM, particularly for the higher ethanol blends at wide open throttle. The addition of DMF however increases the total PM by up to 70% (mass) through the incomplete combustion of the ring structure.

A novel imaging approach was developed for the purpose of counting cells from phase contrast microscopy images of laboratory grown (in vitro) cultures of epithelial cells. Validation through comparison with standard laboratory cell counting techniques showed this approach provided consistent and comparable results, whilst overcoming limitations of these existing techniques, such as operator variability and sample destruction. The imaging approach was subsequently applied to investigate the effects of silver nanoparticles (AgNP) on H400 oral keratinocytes. Concurrent investigations into antimicrobial effects of AgNP were performed on Escherichia coli, Staphylococcus aureus and Streptococcus mutans to provide models for Gram-positive and Gram-negative infection, and to compare with the literature and oral keratinocyte toxicity. It was found that AgNP elicit size-, dose- and time-dependent growth inhibition in both human cells and bacteria, although bacterial inhibition was not achieved without significant cytotoxicity at the same concentrations.

Portland cement (PC) is generally known for its various applications in the construction industry. However, since mineral trioxide aggregate (MTA), a PC based root filling material, obtained food and drug administration (FDA) approval in the late 1990’s there has been an increased interest in the use of the cement for other in vivo applications. PCs are durable, possess high compressive strengths, set in aqueous environments such as those found in vivo and have demonstrated desirable tissue responses as an endodontic sealant. The injectability of PC with various additives was investigated for use in clinical applications such as vertebroplasty (the stabilisation of a fractured vertebra with bone cement) using a syringe with a 2 mm aperture. Additives significantly improved cement injectability, decreased setting times from over 2 h to below 20 minutes while maintaining the compressive strength of the material. Cement characterisation methods including X-ray diffraction (XRD), helium pycnometry and zeta potential measurements were employed to elucidate the effect of the additives on the cement setting reaction. The biocompatibility of PC was investigated with fibroblast and bone marrow cells. The freshly mixed cement appeared cytotoxic while set cement upregulated genes associated with the osteogenic phenotype.

Biocatalysis processes use biologically-derived enzymes to perform fine-chemical synthesis. Whole-cell biocatalysis, using live microorganisms, offers protection against buffer conditions and denaturation, and allows turnover of effective enzymes. However, cells may still be damaged by reaction conditions. In nature, cell populations protect themselves by attaching to surfaces and producing a multi-component protective extracellular matrix. This multicellular mode of growth is termed a biofilm. Biofilms offer many advantages over individual free-floating cells which may be beneficial in whole-cell biocatalysis. The primary aim of this work was to develop a biofilm platform using non-pathogenic Escherichia coli strains as a generic host for various biocatalysis enzymes. To this end, a simple, inexpensive and reliable biofilm generation method was developed and optimised using quantitative assays and confocal laser scanning microscopy. Reporter gene technology was used to provide insight into the expression of the matrix component curli. Flow cytometry was employed to reveal curli expression heterogeneity in biofilm-forming populations. Biofilm-modulating plasmids were used to determine whether improvements could be made to the biofilm-forming strains and their relevant effects were observed. Lastly, three biocatalysis processes were tested in the biofilm biocatalyst with observation of effects on biofilm formation, curli expression and biocatalytic potential.

Nano-biotechnology combines recent advances in nanotechnology with biology. It is a relatively new discipline and full of promise. One such promise is the elucidation of complex bio-molecular reactions and interactions, the elucidation of which requires the development of reliable in-vitro models. Such models could be developed through the use of self-assembled monolayer’s (SAMs). Research into this competitive field has already started and there is currently a call to develop SAMs which present specific bio-molecules in a switchable fashion; switchable SAMs can have their surface properties switched between two states, i.e. they can be switched ‘on’ or ‘off’. Such switch-ability would help such models mimic the real time changes of the bodies’ bio-chemistry and is a vital development. This thesis addresses this current research need, through the employment of azobenzene based SAMs. Currently the switch-ability (isomerisation) of numerous azobenzene SAMs has been shown to be hindered by a lack of inter-surfactant space. This hindrance to isomerisation is addressed in Chapter 4. While Chapter 5 explores the design of an azobenzene based photo-switchable SAM, for use as in-vitro model for the study of bio-molecular interactions. The two chapters are not directly related and future work would aim to bring the findings together.

Poly-ether-ether-ketone (PEEK) is a high performance aromatic thermoplastic with proven biocompatibility. Recently, it has been proposed as a promising bearing material for cervical total disc replacement (TDR). A new bearing combination of PEEK-on-PEEK based self-mating articulation has been used, which may overcome current bearing materials related complications. For ball-on-socket based cervical TDR designs, PEEK based bearing articulation is expected to operate under a boundary lubrication regime regardless of the radial clearance used. The contact stress encountered by the bearing surfaces is insufficient to result in either material yield or fatigue failure. High-cycle fatigue tests were performed on PEEK 450G specimens via three-point flexural bending. The obtained fatigue results (104.1 ± 5.8 MPa) show superiority over the historical polymeric bearing material UHMWPE (31 MPa). Moreover, it demonstrates a good resistance to sterilisation and thermal ageing. Laboratory wear simulation was also conducted, using spine simulators and following ISO 18192-1 standard. For PEEK-on-PEEK self-mating articulation, a steady state wear rate of 1.0 ± 0.9 mg/million cycles is obtained, which is comparable as the historical bearing combination (UHMWPE against CoCrMo). The results of this work suggest that PEEK-on-PEEK based articulation is a possible alternative for future cervical TDR designs.