The essential Smc5/6 complex is structurally related to cohesin and condensin. It is required for homologous recombination (HR), rDNA stability and telomere maintenance. In Schizosaccharomyces pombe, two hypomorphic smc6 mutants, smc6-X and smc6-74, haven been shown to be deficient in HR-dependent processing of collapsed replication forks. Collapsed replication forks can generate single-ended DNA double strand breaks (se-DSB) which require HR to restore replication. In this study the requirement for Smc5/6 at a site-specific se-DSB at the mating-type locus and in the mating-type switch process were analysed. In S.pombe mating-type switching occurs over two S phases; in the first S phase replication fork stalling at mat1 leads to an imprint, which is converted to an se-DSB during the next S phase. This initiates the copying of the donor cassette using HR. In the absences of donors the sister chromatid is used for repair. Mating-type switching analysis showed that snc6-74 had a defect in switching dependent on the genotype of the smc6-74 parent. Both smc6 mutants had reduced viability in the absence of donors, consistent with a defect in HR repair of an se-DSB. analysis in an inducible system (Holmes et al., 2005) showed that in response to a se-DSB Rad52 foci appeared with wild type kinetics but the smc6 mutants delayed entry into mitosis for approximately 2hrs, dependent on the DNA damage checkpoint kinase Chk1. In order to test whether this delay facilitated rescue by a converging replication fork a novel inducible converged fork (cf) DSB system was developed. The cf-DSB required HR and the RecQ helicase Rqh1 for repair but did not require Mus81. The converging fork rescued smc6-74 but not smc6-X showing Smc5/6 to be required for repair of both types of replication-associated DSBs.

This thesis is concerned with the preparation, and subsequent investigation of, titanium dioxide (TiO2) nanomaterials and their ability to remove phenol from gas streams for application towards the abatement of polluted land fill gas (LFG). Using the well documented ability of TiO2 to excite an electron by UV light, phenol was removed from gas streams to investigate the efficacy of TiO2 nanomaterials. Phenol was chosen as a representative VOC but the catalysts were proven to also remove four other organic compounds during gas phase photocatalysis. It was found that in loadings of 1 mol % the degradation of phenol could be increased relative to pristine TiO2 nanofibres. The activity of six metal oxide dopants were fairly compared to one another where it was found that cobalt doped TiO2 showed very high activity, more so than P25 powder. Furthermore, mono-metallic cobalt nanomaterials were shown to degrade phenol in the gas phase, however, more studies are required on these materials. Supports for TiO2 were investigated in order to provide a more practical catalyst for industrial continuous flow reactors. These included novel zeolite:titania composites which were fibrous, non-woven mats of these materials were prepared by electrospinning and were shown to effectively remove phenol from polluted gas stream.

Solar generated hydrogen as an energy source is green, sustainable, with a high energy density. One day the majority of current fossil fuel based technology could be replaced with hydrogen technology reducing CO2 emission drastically. The goal in this research is to explore hybrid metal oxide photocatalysts in the pursuit of achieving highly efficient photoanodes for use in photoelectrochemical cells (PEC). Achieving high efficiencies of hydrogen production in photoelectrochemical cells is the key challenge for the commercialisation of PEC technology as a viable, sustainable, hydrogen source; limited only by the lifetime of the sun and the resources of the metal oxide materials. In this research TiO2, Fe-Ti-O, ZnO, and Zn2TiO4 are the photocatalysts explored. Alloys of Ti-Fe-O showed improvement over TiO2, whilst a hybrid heterostructure of ZnO/Zn2TiO4/TiO2 enhanced photocurrent densities significantly. A barrier layer in the photoanode achieved localised exciton separation and reduction of recombination rates by inhibiting back flow of electrons after injection into the TiO2 layer. Nanotubes are created by the simple electrochemical process of anodisation. The nanotube composition depends on the anode material. To control the composition ofthe anode, iron and titanium are co-deposited onto a substrate using electron beam evaporation. The introduction of iron into titania nanotubes engineered the band gap, lowering the band gap energy to that of iron oxide whilst the positions of the conduction and valence bands with respect to the oxidation and reduction potentials of water remained favourable. Fe-Ti-O nanotubes showed remarkable photocurrent density improvement compared to TiO2 nanotubes. ZnO nanostructures deposited by vapour transport mechanisms showed variability in the morphology of the structures, as governed by the growth dynamics. Herein, it is shown that an electronically favourable situation arises by the formation of a ZnO-Zn2TiO4-TiO2 heterostructure and a high photocatalytic activity is reported. The structure is composed of a large surface area ZnO nanorod photoabsorber formed on a Ti foil which forms a Zn2TiO4 barrier layer between ZnO and TiO2. The Zn2TiO4 layer inhibits electron transport toward the surface of the photoanode whilst encouraging charge transport to the hydrogenation electrode. The heterostructure interfacial surface area is extended through the utilisation of TiO2 nanotubes, which demonstrated a 20.22 % photoelectrochemical efficiency under UV illumination. Surface modification of ZnO nanorods with aerosol assisted chemical vapour deposited TiO2 nanoparticles enhanced photocurrent densities of the ZnO rods, improving charge separation of excitons created within the TiO2 nanoparticles. ZnO nanotubes formed via a novel route using chemical bath deposition of ZnO is investigated, an annulus ZnO seed layer facilitated the site specific growth of ZnO nanotubes whilst a uniform seed layer formed ZnO nanorods.

This thesis reports the synthesis and analysis of a number of organometallic compounds, focusing primarily on novel structures containing Sn and P atoms. Chapter 1 contains a literature review examining the different structural and bonding properties and reactions of C4H4, P4 and P2C2R2. Chapter2 describes the ability of the P2C2tBu2 ligand to cause a reductive elimination in Sn(IV) species. Several different products from the reaction between Me2SnCl2 and Cp2Zr(P2C2tBu2) are determined, and mechanisms for their interconversion are proposed. The synthesis of Sn(P2C2Ad2) is reported along with its unprecedentedly low frequency 119Sn NMR spectroscopic chemical shift. Chapter 3 contains attempts to produce transition metal complexes with phosphaalkyne based ligands. The crystal structure of a complex containing Fe and Zr centres with two P2C2Ad2 rings is reported along with analysis of its paramagnetism. Mechanisms for the exchange of P2C2R2 rings and chlorides are also proposed. Chapter 4 details the synthesis of a range of CpnSnIm species and a comparison of their solid and solution state structures using X-ray diffraction and NMR spectroscopy. Reactions between these compounds and P(SiMe3)3 or LiP(SiMe3)2 are performed in order to explore the possibility of forming a Sn-P multiple bond. Chapter 5 outlines the synthesis of bicyclic systems based on C6H4-1,2-(PH2)2 and Sn and Ge dialkyls. The effect of alkyl group bulk on product structure is investigated. Chapter 6 explores the reaction between C6H4-1,2-(PH2)2 and P(SiMe3)3 in which an exchange of H and SiMe3 groups occurs. The mechanism of the reaction is elucidated by the introduction of a catalytic proton source.

The decreasing availability of fossil fuels and their negative environmental impacts requires urgent need of developing renewable energy. The main objective of this research was to develop low-dimensional nanomaterials for harvesting solar and mechanical energy with high conversion efficiency. In particular, photoelectrochemical water splitting and photovoltaic cell applications driven by sunlight were investigated in this project. A highly efficient triboelectric nanogenerator was investigated for harvesting mechanical energy. The device was further integrated with an organic solar cell for harvesting both mechanical energy and solar energy. My research work started with the synthesis of nanostructured materials. Electrospinning, as well as electrospray, was developed to synthesise nanofibres and hollow hemispheres. The influences of processing parameters to the morphologies and structures of the nanomaterials were systematically investigated. An electrophoretic deposition method was also developed to form good-quality nanostructured metal oxide thin films, which were applied in photoelectrochemical water splitting. The metal oxide hollow hemisphere thin films were also applied in dye-sensitised solar cells. A transparent and flexible triboelectric nanogenerator was developed in order to harvest mechanical energy. The contact electrodes were created using metal nanowire percolation networks embedded in a polymer matrix. The correlation between the energy conversion performances and optical property of the triboelectric electrodes were comprehensively studied as a function of the areal fraction of the metal nanowires. A flexible hybrid cell, integrating the solar cell with the triboelectric device, was designed by constructing an organic solar cell under a single-electrode triboelectric nanogenerator. The hybrid cell could convert both solar and mechanical energies into electricity independently and simultaneously. Such devices are potentially able to supply electricity day and night. Nanomaterials offer novel approaches for enhancing the efficiency of harvesting solar and mechanical energy in a hybrid device.