The Palladium (Pd) based membranes have long been the focus of studies for the separation of hydrogen due to its high permeability and selectivity toward hydrogen. However, palladium is a precious metal and extremely expensive and its wider applications will depend largely on its ability to become economically feasible to compete with other separation technologies. Hence, the main focus of this study is to produce a supported, thin and defect free palladium composite membrane in a cost effective manner. This thesis also highlights some of current advances in palladium research, especially the membrane preparation methods. In this study, the Pd composite membranes were fabricated by depositing Pd metal as a thin layer by using advanced electroless plating coupled with partial suction method onto a 30nm -Al2O3 support. The suction pressure creates a pressure difference between the bore and tube side of the support and this will eventually encourage the transfer of more Pd metal onto the ceramic support, at the same time densifying the deposited layer and simultaneously prevent mass transfer from the film back into the solution, which is the major problem with conventional electroless plating techniques. The final membrane produced has a thickness of about 6 microns with flux in the order of ~0.1 mol/m2s and H2/N2 selectivity of 140 at 673K. The membrane also show its capability in purifying H2 gas using a reformate gas mixtures containing 67% H2, up to the value of 97.3% pure H2 in a single stage pass at 673K at low pressure differentials of 0.8 barg. Studies conducted also investigate the effects of electroless plating condition and parameters in their resulting relationship with the pore sizes of the ceramic support have on the palladium layer deposited.

The work presents a novel framework for the synthesis and optimisation of complex design processes that combines superstructure-based optimisation, semantic models (in the form of ontologies) and analytical tools. The work addresses the representation and extraction of process synthesis knowledge during the optimisation process with the purpose to simplify and interpret design results. The simplification relies on a gradual evolution of the superstructure and corresponding adjustments of the optimisation search. The interpretation is accomplished with the use of analytical tools to translate data into descriptive terms understood by users. Means of analysis include dynamic ontologies populated by computer experiments and continuously upgraded in the course of optimisation. In such a way, knowledge is developed throughout the search. The systematic interpretation of the solutions yields to an understanding of the solution space and to a systematic reduction of the representation employed. The presented approach overcomes the inconclusiveness and difficulty of translation of the solutions usually found in classical stochastic optimisation approaches as well as reduces the experiments to be performed. The approach enables monitoring the search, which is carried out in terms of the extraction of design classes at each optimisation stage. The work explains the integration of the components of the framework and gives detail of its implementation. The framework is presented for the synthesis of isothermal reactor networks, essentially addressing the challenges of a multi-level optimisation problem approached with stochastic tools. However, the approach is not restricted to any particular type of application or optimisation method. The developments are illustrated with various examples from the literature and from industry. Results show how important features and patterns are retrieved at very early stages of process design and demonstrate how the approach reduces the complexity often involved in the final solutions delivering much more clear and simple design configurations as only important features with strong impact on the performance are represented. The designer is provided with optimal design patterns that translate into practical designs rather than complex structures

The central issue to be addressed in this thesis is the provision of support for design tasks that require problem formation and evaluation and some inventive adaptation of products and design strategies. Hitherto, computer tools have failed to support the full range of design tasks. In particular, they have been focused upon solving previously formulated design tasks in well-defined domains where little inventiveness with materials or design strategies is required (Green, 1992a). A solution is offered in the form of an analysis that yields a new class of system, called Method Oriented Design Environments (MODEs), which provide support for some of these more complicated design tasks. An implementation of such a system is presented in the fom1 of Patina: a MODE to support parametric analysis. It is argued that the lack of support for design tasks involving problem formulation, evaluation and inventiveness with components and strategies has partly been due to usage of an overly narrow view of the design process as a basis for system development on the part of developers of knowledge aided design. To provide a more complete orientation for these developers, and 'to expand the theory of knowledge aided design, an alternative model of design tasks is developed in the form of a 'design activity space' by transferring knowledge from the field of design research to that of knowledge aided design. A mapping is constructed between this new design activity space and Green's model space of tools for knowledge aided design (Green, 1992a). The mapping is first used to analyse the range of utility of some recent alternatives to traditional knowledge based systems for design. It is then used to single out a 'niche' of design tasks that are not supported by traditional systems or their more recent alternatives. The design tasks which lie in this niche awaiting support from computer tools share the following characteristics: ( 1) they encompass the activities of analysis, synthesis and evaluation, (2) they require an intermediate degree of innovation with the product, and (3) they require an intermediate degree of innovation in design strategy. The class of tools that are proposed to offer support to tasks in this niche are named MODEs because their defining characteristic is that the majority of their constituent knowledge is derived from a design method or strategy. Therefore the main item that is being represented to the user of a MODE is such a structured method rather than an evolving artefact. This is radically different from the traditional knowledge based tools, where the item being represented is an artefact in a particular domain, and from a recent proposal for systems that depict an unstructured process (Blessing, 1994). To demonstrate the feasibility of implementing a MODE, the implementation of a system called Patina, to support designers in applying the technique of parametric analysis, is reported.

Microcantilevers have now been used successfully for over a decade. New assays are being developed and tested continuously but the technique has not arrived in hospitals and surgeries yet. The main obstacle was that a robust and reliable readout system which does not need intricate alignment before each measurement was not available. Therefore cantilever devices have only been used in university laboratories. The aim of the research presented in this thesis is to provide a diffractive optical readout for cantilever bending that is rapid, robust and easy to use. The diffractive readout discovered during my PhD involves a laser illuminating the entire cantilever and additionally parts of the chip base to which it is attached. The laser light diffracted from the cantilever contains information that allows a distinction to be made between tilting and bending of the cantilever. Additionally, measurements of the absolute tilting and bending can be performed and the time needed for aligning the cantilever chip in the laser beam is reduced to a minimum. This thesis describes the tools used to develop the diffractive readout and presents experimental results. First, a simulation was programmed to predict results and optimise experimental conditions. Second, an experimental setup was built from scratch and a new ow cell designed which was needed for transmission mode experiments. Third, test experiments in air were performed using a transmissive and a reflective diffraction approach. Fourth and finally, the applicability of the diffractive readout was shown by demonstrating that the binding of the antibiotic vancomycin to a glycopeptide could be measured successfully. I hope that the invention presented in this thesis will help to commercialise the cantilever setup and make it attractive for the use in hospital and surgeries speeding up diagnostic steps from days down to a few minutes. This thesis lays the cornerstone of the discovered, patented and tested optical diffractive readout technique for cantilever based biosensors. Optimisation of the experiment, being very important and essential, has to be focused on in the future and is not dealt with in detail in here.

This thesis describes experimental work carried out on bilayer manganites with the general composition R_{2-2x}A_{1+2x}Mn_2O_7, where R is a trivalent rare earth cation and A is a divalent alkaline-earth cation. Experiments have been carried out primarily using Scanning Tunnelling Microscopy (STM) and Spectroscopy (STS); bulk electrical transport, MPMS and LEED measurements have also been made. The primary results are obtained from single crystal samples of PrSr_2Mn_2O_7. This compound provides a surface suitable for STM study when cleaved at low temperature in ultra-high vacuum: atomic resolution can be readily achieved. The expected square lattice is observed, together with a larger scale surface modulation which is not presently explained. In some areas of the PrSr_2Mn_2O_7 surface a population of adatoms and surface vacancies is observed. STS data indicate that adatoms carry a negative charge compared to the rest of the surface, and vacancies a positive charge: the adatoms and vacancies are interpreted as oxygen adatoms and oxygen vacancies. A detailed study is made of the oxygen adatoms and vacancies: this is believed to be the firrst such study made on a manganite surface. Oxygen adatoms on the PrSr_2Mn_2O_7 surface are found to be mobile: hopping and adatom-vacancy recombination are observed. Additional results are reported on the layered manganite compound La_{2-2x}Sr_{1+2x}Mn_2O_7 at a range of cation doping x. For the LaSr_2Mn_2O_7 compound (x = 0.5) spectroscopic variation has been identi_ed in a variable-temperature STS survey. This indicates the coexistence of two surface electronic phases, possibly the charge ordered and antiferromagnetic phases.

This thesis describes the experimental investigations of geometric frustration in magnetic oxides. The rare earth double perovskites Ba2HoSbO6 and Ba2ErSbO6 crystallise into the Fm3m cubic space group with the rare earth ions forming a face centred cubic arrangement of edge sharing tetrahedra. This arrangement is expected to result in geometric magnetic frustration. Previous studies have revealed no long range order or spin glass behaviour down to 1.5 K. In this work, low temperature neutron scattering measurements were carried out to investigate the magnetic behaviour below 1.5 K. The crystalline electric field was found to dominate the magnetic behaviour. Using experimental results from inelastic neutron scattering the crystal field level scheme was solved for Ba2HoSbO6 and Ba2ErSbO6. These results were used to successfully predict the observed behaviour of both systems, showing that they can be considered to behave as single ion systems down to the lowest temperature investigated of 0.06 K. As such exchange interactions and any effects of frustration are not evident at the temperatures investigated. As a further step to investigate frustration in magnetic oxides LuCuGaO4 was considered. This has triangular bilayers of magnetic Cu2+ and non-magnetic Ga3+ that are expected to lead to two dimensional geometric magnetic frustration of the Cu2+ ions. The presence of Ga3+ on the same lattice site as the Cu2+ lead to charge frustration. Polarised neutron analysis, inelastic neutron scattering and \muSR build up a coherent picture of the low temperature behaviour of the system which questions the previous belief in the literature of a spin glass transition. Instead what is found is a spin liquid state. Finally, the problem of interpreting the subtle features and signatures of frustration is considered with an alternative \muSR technique. \muSR allows local interactions to be investigated, however the problem of interpreting the results can lead to ambiguity. It is shown that it is possible to successfully implant muons outside the sample of interest and accurately measure the sample’s magnetic dipolar field. In this way \muSR can be used as a bulk magnetometer with the same frequency response as standard \muSR and it is shown that this can be useful in the investigation of frustrated materials with reference to results on Tb2Sn2O7.

This thesis contains a series of density functional studies on porphyrins, surfaces and other molecules, that are of relevance to surface science and electron transfer. In chapter 1 the main concepts of the thesis and how they fit together, are outlined. Chapter 2 describes density functional theory (DFT), the principle theoretical technique used throughout. The thesis then considers two main aspects. Chapters 3, 4 and 5 look at how systems interact with surfaces and compare and contrast situations of differing interaction strengths. Chapter 3 investigates the weak interaction of a haem molecule with the Si(111):H surface and studies how this interaction can be tuned by desorbing hydrogen atoms from the surface. In chapter 4, the structure of experimentally observed Mn nanolines on the Si(001) surface is studied. How these lines self assemble and interact strongly with the surface is discussed. Elements of these two studies are then combined in chapter 5 with a study of manganese porphyrin on the Si(001) surface displaying some features common to both previous systems. In chapter 6, 7 and 8 the focus switches to electron transfer. The basics of electron transfer theory are outlined in chapter 6. Then, the difficulties faced by DFT when studying electron transfer in large systems, such as the self-interaction error and cubic scaling, are described. Chapter 7 describes the constrained DFT formalism and its implementation into the linear scaling DFT code CONQUEST. In chapter 8, this implementation is used to perform some electron transfer calculations on small organic molecules, with systems demonstrating both charge localization and charge separation investigated. Chapter 9 concludes the thesis indicating how, following this thesis, large scale electron transfer calculations of organic molecules on surfaces can be performed with some confidence and giving suggestions for future calculations.

Radiation damage has traditionally been modelled using classical molecular dynamics, in which the role of the electrons is confined to describing bonding via the interatomic potential. This is generally sufficient for low radiation energies. However high energy atoms lose a significant proportion of their energy to electronic excitations, therefore a simulation of the relaxation of a metallic lattice after a high energy event requires a description of the energetic interaction between atoms and electrons. The mechanisms of inelastic collisions between electrons and ions, coupling between electrons and phonons and the diffusion of energy through the electronic system to the rest of the lattice become signficant. We have coupled large scale MD simulations of the lattice to a continuum model for the electronic temperature evolution. Energy lost by the atoms due to elastic and inelastic electronic collisions is gained by the electronic system and evolves according to a heat diffusion equation. The electronic energy is coupled to the lattice via a modified Langevin thermostat, representing electron-phonon coupling. Results of the simulation of both displacement cascades and ion tracks, representing the low and high extremes of incident ion energy respectively, are presented. The effect of annealing of pre-existing damage by electronic excitation is studied and the behaviour under swift heavy ion irradiation in iron and tungsten is compared. In simulations of displacement cascades, the strength of coupling between the atoms and electrons emerges as the main parameter determining residual damage. Our new methodology gives rise to reduced damage compared to traditional methods in all cases. Ion track simulations demonstrated that the relaxation dynamics, and hence the residual damage, was dependent on the magnitude and temperature dependence of the electronic thermal parameters.

In recent years advances in the processing and purification of detonation nanodiamonds has renewed interest into their research, from the basic properties of detonation nanodiamonds to their applications in areas from electronics to biology. Using a colloid of mono dispersed detonation nanodiamonds it is possible to coat various substrate materials. This thesis reports on the suitability and enhancement of nanodiamond coatings for electronic applications. Atomic force microscopy is used to investigate the deposition of nanodiamond particles on substrates. The electrical characteristics of mono-dispersed nanodiamond layers are investigated using impedance spectroscopy, establishing that the layers have high quality dielectric characteristics. Hydrogen terminated CVD diamond is known to have a negative electron affinity (NEA), making it a suitable material for secondary electron emission. This thesis investigates using and optimising nanodiamond coatings on microchannel plates (MCPs) to increase the secondary electron yield of these devices, thereby improving the performance of image intensifiers. The as-received nanodiamond is covered with surface functional groups dependent on post detonation treatments for cleaning and deaggregation. Treatments have been designed which modify the surface groups for homogeneity, followed by an oxidation treatment to provide a platform for metallisation, notably caesium oxide which is known to give a stable and larger NEA surface thus further improving the secondary electron yield. Fourier transform infra-red spectroscopy and has been used to investigate the presence of functional groups. A comprehensive study of the secondary electron emission yield of nanodiamond coatings after various surface treatments is presented. The most effective treatment is found to be a low temperature chemical vapour deposition process which is compatible with the fragile MCP structure. SEM and Raman spectroscopy have been used to provide an insight into the changes of the material, which remains nanodiamond-like. These are the first such results from nanodiamond material.

Obstruction of the lacrimal drainage system can lead to constant tearing (watery eyes, “epiphora”) resulting in irritation of the eye region, disturbed vision and therefore serious reduction of life comfort. Watery eyes are a frequently encountered symptom in daily ophthalmological practice more seen in the elderly patient, but also in young people and children. Current treatment options of epiphora due to lacrimal duct obstructions in the upper part of the drainage system are very limited. In 1963 Lester Jones developed a bypass system formed by a rigid glass tube guiding the tear straight into the nasal cavity. This tube causes frequent complications due to dislocation, blockage and irritation of the eye and nose. Other options include reopening of the drainage system with drills or lasers and placement of stents. None of these options are optimal. The aim of this research was the development of a new lacrimal duct device using a novel nanocomposite polymer based on polyhedral oligomeric silsesquioxanes (POSS) nanoparticles and poly (carbonate-urea)urethane (PCU). POSS self assembles on surface during extrusion and creates a nanotopography surface. The small diameter conduit was manufactured for replacement of a non-functional or missing upper lacrimal duct (canaliculus). Several methodologies including ultrasound atomisation, electrodynamic spraying, dip coating and coagulation techniques were used to construct a lacrimal drainage conduit (LDC) using POSS-PCU, with a diameter of 800 μm representing the size of a canaliculus. In a further development of the research we manufactured a POSS-PCU nanocomposite modified with silver nanoparticles (nanosilver) enhancing the antimicrobial and antiscarring properties of the conduit. Extensive material testing was performed to optimise the synthetic LDC. Finally, the LDC made of POSS-PCU with nanosilver was implanted for the first time in human, in a 41-year old patient in a compassionate case with successful outcome.