Surface defects, such as rolling contact fatigue (RCF) cracking, can be a difficult class of surface defects for existing on-line non-destructive testing techniques to detect and size accurately at high speed. Gauge corner cracking on the running surface of the railway track is a type of RCF defect. There are economic and safety benefits to have an accurate, fast and reliable NDT technique to detect such defects. The EMAT pitch-catch ultrasonic testing technique, using the Rayleigh surface wave developed at the laser ultrasound group, has been shown to be able to detect and size surface defects. The pitch-catch geometry also allows this technique to be used at high speed, for on-line NDT applications.

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This thesis is concerned with the mechanical properties and pH-dependent conformation of macromolecules at the silica-water interface. It is believed that the adhesion of bacteria to solids is governed by long-range interactions and by immediate interactions between bacterial surface polymers and solid surfaces. For a flexible macromolecule, the interaction of its segments with a solid surface and the conformation it takes at the interface are prominent factors in determining the net interaction to solids.

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An advection-diffusion model has been set up to describe normal grain growth. In this model grains are divided into different groups according to their topological classes (number of sides of a grain). Topological transformations are modelled by advective and diffusive flows governed by advective and diffusive coefficients respectively, which are assumed to be proportional to topological classes. The ordinary differential equations, governing self-similar time-independent grain size distribution can be derived analytically from continuity equations. It is proved that the time-independent distribution obtained by solving the ordinary differential equations have the same form as the time-dependent distributions obtained by solving the continuity equations. The advection-diffusion model is extended to describe the stagnation of normal grain growth in thin films. Grain boundary grooving prevents grain boundaries from moving, and the correlation between neighbouring grains accelerates the stagnation of normal grain growth. After introducing grain boundary grooving and the correlation between neighbouring grains into the model, the grain size distribution is close to a lognormal distribution, which is usually found in experiments. A vertex computer simulation of normal grain growth has also been carried out to make a cross comparison with the advection-diffusion model. The results from the simulation did not verify the assumption that the advective and diffusive coefficients are proportional to topological classes. Instead, we have observed that topological transformations usually occur on certain topological classes. This suggests that the advection-diffusion model can be improved by making a more realistic assumption on topological transformations.

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This thesis describes electron injection into thin films of thermally grown SiO(_2) and also Zn(_2)SiO(_4):Mn. Electrons are accelerated to high energies in the depletion field of a reverse biased, shallow (l000 Ǻ deep), planar p-n(_+) junction, and directed towards the silicon and thin film interface. The injection process is aided by the additional application of an electric field across the thin films. The form of the injected current dependence on the field applied across the films and with junction avalanche current is found to be consistent with electron injection from localised microplasmas within the shallow junction. The experimental results indicate that there is a near exponential rise in the injected current with increasing junction current. Previous explanations for similar dependences are shown to have several deficiencies when applied to the present structures. A new model of electron injection is proposed which is based on microplasma switching probabilities. Numerical approximations when applied to the microplasma injection model are shown to give acceptable agreement with experimental results. The fabrication of the shallow junction injection structures is described in detail and also the thin film formation, techniques. A proposed injection structure which should give a more uniform electron injection is also described.

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