<p>Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials collected from selected deposits using different mixing proportions of clay, feldspar and quartz. Their properties in relation to workability, firing temperature, dielectric and bending strengths are studied. It is found that a mixture consisting of 30% Mutaka kaolin, 15% Mukono ball clay, 30% Mutaka feldspar and 25% Lido beach flint yields a body with highest mechanical strength (72MPa) and dielectric strength (19kV/mm) when fired at 1250°C. The strength (both mechanical and dielectric) is found to decrease with increasing firing temperature. At high firing temperatures, the undissolved quartz in the body decreased, the glass content increases and pores are formed. Mullite content on the other hand does not change at temperatures above 1200°C but there are significant differences in the morphologies of the mullite crystals in the samples. Optimum mechanical and electrical properties are found at maximum virtification and a microstructure showing small closely packed mullite needles.</p>

This thesis is concerned with the development and characterisation of polymeric nanoporous adsorbents to be used for blood purification. Current treatment methods for suffers of chronic renal failure are limited to haemodialysis, peritoneal dialysis and organ transplant. Organ transplant is the most efficient option however lack of donor organs mean that the majority of suffers rely on dialysis. Unfortunately both dialysis treatments are lacking when it comes to the removal of middle molecular weight molecules (MMs) (500 - 60000 Da) and the accumulation of these molecules has been attributed to a number of additional ailments suffered by those on long term dialysis. Sorbent augmented dialysis has been identified as a potential avenue to remove these MMs, an additional column would be introduced to the haemodialysis loop this would contain adsorbent particles to remove these unwanted molecules. Styrene-divinylbenzne copolymers have been identified as suitable for this task as they will non-specifically adsorb a wide range of molecules. One major concern with the introduction of a polymeric adsorbent is the potential removal of human serum albumin HSA from the patient's blood, this essential blood protein is present in very high concentrations typically 40g/l and this will potentially swamp the surface of any adsorbent. Fortunately HSA is a large blood protein (69kDa) and as such the method to combat this limitation as explored in this thesis is to tailor the pore structure of the polymeric adsorbent to size exclude albumin while retaining sufficient adsorption capacity to remove the MMs. To achieve these goals a number of polymeric adsorbents were generated using different porogens and degrees of crosslinking to control the porous structure. These adsorbents were analysed using a number of characterisation methods to assess their dry and swollen state porosities and molecular weight cut offs. Once a suitable material had been developed protein adsorption studies were carried out to confirm the size exclusion of HSA and the uptake of MMs.

In 2010 and 2011 Christchurch, New Zealand experienced a series of earthquakes that caused extensive damage across the city, but primarily to the Central Business District (CBD) and eastern suburbs. A major feature of the observed damage was extensive and severe soil liquefaction and associated ground damage, affecting buildings and infrastructure. The behaviour of soil during earthquake loading is a complex phenomena that can be most comprehensively analysed through advanced numerical simulations to aid engineers in the design of important buildings and critical facilities. These numerical simulations are highly dependent on the capabilities of the constitutive soil model to replicate the salient features of sand behaviour during cyclic loading, including liquefaction and cyclic mobility, such as the Stress-Density model. For robust analyses advanced soil models require extensive testing to derive engineering parameters under varying loading conditions for calibration. Prior to this research project little testing on Christchurch sands had been completed, and none from natural samples containing important features such as fabric and structure of the sand that may be influenced by the unique stress-history of the deposit. This research programme is focussed on the characterisation of Christchurch sands, as typically found in the CBD, to facilitate advanced soil modelling in both res earch and engineering practice - to simulate earthquake loading on proposed foundation design solutions including expensive ground improvement treatments. This has involved the use of a new Gel Push (GP) sampler to obtain undisturbed samples from below the ground-water table. Due to the variable nature of fluvial deposition, samples with a wide range of soil gradations, and accordingly soil index properties, were obtained from the sampling sites. The quality of the samples is comprehensively examined using available data from the ground investigation and laboratory testing. A meta-quality assessment was considered whereby a each method of evaluation contributed to the final quality index assigned to the specimen. The sampling sites were characterised with available geotechnical field-based test data, primarily the Cone Penetrometer Test (CPT), supported by borehole sampling and shear-wave velocity testing. This characterisation provides a geo- logical context to the sampling sites and samples obtained for element testing. It also facilitated the evaluation of sample quality. The sampling sites were evaluated for liquefaction hazard using the industry standard empirical procedures, and showed good correlation to observations made following the 22 February 2011 earthquake. However, the empirical method over-predicted liquefaction occurrence during the preceding 4 September 2010 event, and under-predicted for the subsequent 13 June 2011 event. The reasons for these discrepancies are discussed. The response of the GP samples to monotonic and cyclic loading was measured in the laboratory through triaxial testing at the University of Canterbury geomechanics laboratory. The undisturbed samples were compared to reconstituted specimens formed in the lab in an attempt to quantify the effect of fabric and structure in the Christchurch sands. Further testing of moist tamped re- constituted specimens (MT) was conducted to define important state parameters and state-dependent properties including the Critical State Line (CSL), and the stress-strain curve for varying state index. To account for the wide-ranging soil gradations, selected representative specimens were used to define four distinct CSL. The input parameters for the Stress-Density Model (S-D) were derived from a suite of tests performed on each representative soil, and with reference to available GP sample data. The results of testing were scrutinised by comparing the data against expected trends. The influence of fabric and structure of the GP samples was observed to result in similar cyclic strength curves at 5 % Double Amplitude (DA) strain criteria, however on close inspection of the test data, clear differences emerged. The natural samples exhibited higher compressibility during initial loading cycles, but thereafter typically exhibited steady growth of plastic strain and excess pore water pressure towards and beyond the strain criteria and initial liquefaction, and no flow was observed. By contrast the reconstituted specimens exhibited a stiffer response during initial loading cycles, but exponential growth in strains and associated excess pore water pressure beyond phase-transformation, and particularly after initial liquefaction where large strains were mobilised in subsequent cycles. These behavioural differences were not well characterised by the cyclic strength curve at 5 % DA strain level, which showed a similar strength for both GP samples and MT specimens. A preliminary calibration of the S-D model for a range of soil gradations is derived from the suite of laboratory test data. Issues encountered include the influence of natural structure on the peak-strength–state index relationship, resulting in much higher peak strengths than typically observed for sands in the literature. For the S-D model this resulted in excessive stiffness to be modelled during cyclic mobility, when the state index becomes large momentarily, causing strain development to halt. This behaviour prevented modelling the observed re- sponse of silty sands to large strains, synonymous with “liquefaction”. Efforts to reduce this effect within the current formulation are proposed as well as future research to address this issue.

The aim of this work was the study of sputtered zinc oxide (ZnO) film deposition, the optimisation and characterisation of film properties and applications as a sensing material. In recent years there has been increased interest in ZnO in terms of its potential applications as piezoelectric films (or coatings) for surface acoustic wave devices (SAW), for IR and visible light emitting devices and UV sensing. The electrical, optoelectronic and photochemical properties of undoped ZnO have resulted in its use for solar cells, transparent electrodes and blue/UV light emitting devices. ZnO is a unique material that exhibits both semiconducting and piezoelectric properties. In the past decade, numerous studies have been made on both production and application of one-dimensional ZnO. Compared with other semiconductor materials, ZnO has a higher exciton binding energy of 60 meV, which gives it a high potential for room temperature light emission, is more resistant to radiation, and is multifunctional as it has piezoelectric, ferroelectric, and ferromagnetic properties. ZnO-based semiconductor and nanowire devices are also promising for the integration on a single chip. So far, the various applications of ZnO nanomaterials such as biosensors, UV detectors and field emission displays are being developed. In this work, ZnO was sputtered using both DC and RF magnetron sputtering. Reactive DC sputtering was performed with a Zn target and oxygen plasma, while RF sputtering was performed with a ZnO target. Comparisons between films deposited under different conditions on different substrates were employed to assess film properties. Several experiments were performed on as-grown films as a control for subsequence treatments, other samples were post-annealed in N2 at temperatures up to 1200 ºC, the highest reported annealing temperature and the quality of the deposited films was determined using PL, RBS, XRD, SEM and AFM. The piezoelectric properties (d33) of selected films were determined using single beam interferometry, double beam interferometry, and for the first time, using piezoelectric force microscopy (PFM). It was found that DC sputtered films yielded better quality films as evident by PL and XRD analysis and higher piezoelectric response than RF sputtered films. Films deposited using DC sputtering on Si substrates and followed by post-annealing in N2 atmosphere at 1100 ºC showed the highest recorded PL response, while films deposited on sapphire showed good PL response without any need for post-annealing. The d33 of selected films were determined first using single beam interferometry and inflated results were reported, caused by sample bending/buckling. Double beam interferometry results confirmed d33 values in the range of 3.3 to 4.3 pm/V. Piezoelectric force microscopy (PFM) which is based on AFM, was employed to investigate the local electromechanical (piezoelectric) properties of the ZnO films. UV sensing was demonstrated using Schottky contacts and SAW devices on ZnO deposited on Si and post-annealed. In the first instance, Schottky contacts were fabricated on the films and the I V characteristics determined under exposure of various light sources. The current increased up to one order of magnitude during exposure with a halogen light bulb, which is known to emit energy in the UV band. Another experiment was performed using surface acoustic wave (SAW) devices which were fabricated on the films and interrogated using a network analyser. These SAW devices contain an interdigitated transducer and two reflectors each. The signals sent back from the two reflectors were analysed under various light conditions and gave lower readings during exposure to UV light. In order to enable device fabrication of UV sensors a novel “super coating”, achieving both optimised PL and d33 properties, was designed, fabricated and tested. The structure is based on optically transparent Quartz substrate. During this experiment the first DC sputtered coat was optimised to have high PL response by post-annealing at 900 ºC. Afterwards, the second coat was left as-sputtered in order to have highly piezoelectric properties. Preliminary analysis using XRD showed two peaks corresponding to the annealed and not annealed coat, which suggest the super coating combines the properties of the two individual films. This configuration has the potential to be used as UV sensing material and as piezoelectric substrate for SAW devices.

Xylella fastidiosa is a small, xylem-limited bacterium that causes a number of diseases in over 100 species of plants. Many of the species infected are economically important (such as coffee, grapevines, citrus, and almond) and billions of dollars worldwide are lost annually due to X. fastidiosa infection of crops. The bacterium colonises both plant and insect hosts, using the insect host to transfer it from plant to plant. Sequencing of the X. fastidiosa genome in 2000 discovered that while the genome is reduced, it contains a high number of putative bifunctional enzymes. One of these enzymes, aspartate kinase:diaminopimelate decarboxylase (AK:DapDc), occurs in only a handful of species and is predicted to catalyse the first and last steps of lysine biosynthesis. This study reports the first experimental characterisation of this enzyme. AK:DapDc was over-expressed in the pET30dSE plasmid in Escherichia coli BL21 DE3 cells. It was purified by Ni2+ His-Trap chromatography followed by size exclusion chromatography. Homology models of AK:DapDc were created in SWISS-MODEL, which indicate homology with the aspartate kinase from Arabidopsis thaliana and the diaminopimelate decarboxylase from E. coli. Circular dichroism, and analytical ultracentrifugation were used to obtain information about the secondary and quaternary structure of AK:DapDc. This data, in combination with the homology models, suggests that AK:DapDc exists as a dimer or tetramer in solution. A coupled enzyme assay to assay for diaminopimelate decarboxylase activity has been set up, and preliminary crystal screens have been carried out.

Candida species are ubiquitous, ranging from pure saprobes through endo-symbionts of animals, to pathogens in many animals including humans. Some of the pathogenic species are of medical importance, especially Candida albicans. However, the prevalence of other non-albicans Candida species as human pathogens has been increasing worldwide. The aim of this study was to use conventional phenotypic tests and molecular methods to isolate, identify and characterise 600 Candida isolates from three teaching hospitals in Ghana, namely Korle Bu, Komfo Anokye and Tamale from mid-January to April, 2012. The prevalence of these species in cases of genitourinary candidiasis and pelvic inflammatory disease was investigated. Preliminary identification and characterisation of Candida isolates using four conventional phenotypic tests showed that C. albicans was the most common species, which constituted 41% of the isolates whereas non-albicans Candida species constituted 59% of the total number of Candida isolates. In patients presenting with vulvovaginal candidiasis (VVC) for at least two or more times, chi-square analysis indicates that the frequency of Candida species isolated were not statistically different from patients presenting for the first time with VVC. Candida albicans was the most common species in vaginal swabs from patients presenting with vulvovaginal candidiasis (VVC) for the first time in each of the three locations, present in 53.4% of the total swabs. The other species that were present were C. glabrata (21.6%), C. parapsilosis (15.5%), C. tropicalis (4.7%) and C. krusei (4.7%). Similar Candida species distributions were found in swabs taken from patients presenting with suspected pelvic inflammatory disease (PID). Across the three locations, however, there was a significant difference in the frequency of C. albicans, which was present in 68 and 69.6% of patients from Komfo Anokye and Tamale, but only 26.7% of patients from Korle Bu. Urine samples were taken in two of the locations, Korle Bu and Tamale, from female patients presenting with candiduria. Statistical analysis indicated a significant difference in the frequency of Candida isolates in cases of candiduria between the two locations. In Korle Bu, C. glabrata was the most prominent species (37.8%) followed by C. albicans (22.4%), C. parapsilosis (21.7%), C. tropicalis (10.5%), C. krusei (7%) and C. lusitaniae (0.7%). In Tamale, the species distribution was C. albicans (60.9%), C. glabrata (21.7%), C. parapsilosis (13%) and C. krusei (4.3%). The data highlight the prevalence of species other than C. albicans in case of candidiasis in Ghana. Delineation of C. albicans strains using the 25S rDNA to investigate the genotypic variation among C. albicans isolates showed that genotype A constituted about 95% of the Ghanaian C. albicans isolates, genotypes B and C constituted 2.5% each respectively. The general-purpose genotype (GPG) which corresponds to clade 1 among C. albicans was also investigated to know the prevalence of clade 1 among the C. albicans isolates investigated. The presence or absence of general-purpose genotype (GPG) gene was used to categorise the 240 C. albicans to clade 1 or other clade. The test revealed that 64.2% had the GPG genotype which corresponds to clade 1 and the remaining 35.8% were of non-GPG genotype; thus belongs to other clades. The population structure of C. albicans from the three teaching hospitals indicates a mainly clonal and homogeneous population across the three sampling locations from Ghana. Molecular analyses of the transposable group 1 intron in the ITS1-5.8S-ITS2 region using universal primer pair ITS1 and ITS4 revealed the presence of two rare Candida species; Candida rugosa and Candida mesorugosa. To the best of my knowledge this is the first report of either of these in Africa. Antifungal susceptibility tests among Candida isolates recovered from patients presenting with clinically suspected or symptomatic candidal vaginitis for the first time and patients presenting with candidal vaginitis on two or more occasions revealed a high percentage of Fluconazole-resistant C. albicans. This study highlights the prevalence of species other than C. albicans in cases of candidiasis in Ghana. Furthermore, this study has also demonstrated that no single conventional phenotypic test has been highly efficient to delineate Candida species into their respective species type. Thus, development of an identification scheme, which can discriminate between Candida isolates both at species and strain levels, will have prognostic and therapeutic significance for effective patient management.

Novel approaches to the determination of material properties and damage parameters of fibre-matrix composites using inverse analysis are presented. In inverse analysis system identification techniques are used to update some form of mathematical model (normally a FE model) using data from an over-determined number of tests. Initially, pultruded GFRP box-section beams are subjected to a quasi-static impact or bending crush. The results of the impact tests are presented to corroborate those in the literature that have been obtained using simpler geometries such as flat plates. In the first form of inverse analysis, a model-updating approach is applied to progressive tearing damage in pultruded composite box-section beams. The difference between empirical data (from a programme of three-point bend tests) and a FE model is minimised by a genetic algorithm to produce an optimal solution. The solution is in the form of a FE model that can be subsequently analysed to determine the structural integrity of the damaged specimen. Secondly, a unidirectional composite disc from the same GFRP pultruded section is analysed in diametral compression to both verify and improve the validity of the diametral compression test in determining the material properties. Coupons are cut from damaged specimens and test results are presented. The strain distribution within the disc is compared to known laminate theory in order to process data obtained by speckle-shearing interferometry. Finally, speckle-shearing interferometry is used to characterise the response of the pultruded box-section exhibiting progressive tearing damage. Out-of-plane displacement-gradient data is used to determine and characterise damaged regions or flaws. The differences between the need to perform it programme of unequivocal static tests and the collection of full-field optical data are highlighted. It is shown that the shearing interferometry approach is the superior method.

Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term semiautonomy is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of 'mood'. The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships. There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can 'feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the 'mental physics' of the MM may open up new possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood PCs are in they can cast different 'spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which 'affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities.Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term \textit{semiautonomy} is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of 'mood'. The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships. There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can 'feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the 'mental physics' of the MM may open up new possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood PCs are in they can cast different 'spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which 'affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities. / A thesis submitted in 2009 in partial fulfilment of the requirements of the University ofTeesside for the degree of Doctor of Philosophy. The research programme was carriedout at and with the support of Gotland University.

This thesis describes the synthesis and characterisation of new examples of meso-n1-organometallic porphyrins. These porphyrins were originally encountered as catalytic intermediates in the C-C bond forming reaction on the porphyrin periphery using palladium catalysts. They have now become a research topic in their own right and no other examples of this type of organometallic porphyrins had been reported at the outset of this work. In Chapter 2, several examples of meso-palladioporphyrins were prepared in high yield using oxidative addition of the porphyrin-bromine bond to a suitable Pd(0)phosphine precursor. These phosphine precursors were prepared from Pd(PPh3)4 or Pd2dba3 plus either PPh3 or a chelating diphosphine. Several new examples of mono- and di palladium complexes of chelating diphosphines were prepared. Chapter 3 looks at the preparation of meso-platinioporpyrins and the insertion of various central metal ions into the porphyrin ligand. Pairs of cis- and transisomers of the Pt(II) complexes were isolated from the oxidative addition of Pt(PPh3)3 to the free base and Ni(II) bromoporphyrins. The cis-isomer converted to the trans upon heating. At room temperature the two isomers are geometrically stable and survive unchanged through column chromatography and slow recrystallisation. The central metal ion can be introduced either before or after the oxidative addition to Pt(0). However, it is preferable to insert the metal ion last as the complexes of Br(MDPP) are rather insoluble (especially that of MnCl) and are more difficult to handle than the common intermediate trans- [PtBr(H2DPP)(PPh3)2]. The oxidative addition of Pt(dba)2 to meso-bromo-DPP in the presence of PPh3 has also been shown to be an effective method of synthesising n1-organo platinum porphyrins in high yield. However, this method was unsuccessful when using chelating diphosphines. In Chapter 4, the physical properties of meso- metalloporphyrins are reported including electrochemistry, fluorescence spectroscopy and crystal structure determinations. The fluorescence intensities of the meso-substituted porphyrins (freebase and zinc complexes) are dramatically reduced in comparison with the unsubstituted porphyrins. This fluorescence quenching is a dramatic example of the "heavy atom effect". Electrochemical measurements of freebase and Ni(II)porphyrins indicate that the organometallic fragment is a strong electron donor. The visible absorption spectra for all Pd(II) and Pt(II) complexes are typical for diarylporphyrins. All groups other than H in the 5- or 5- and 15-positions cause a red shift of the major absorption bands for both the free bases and central-metal complexes. The crystal structure studies of the Pt(II) complexes include the complexes, cis- [PtBr(MDPP)(PPh3)2] (M = H2, Ni), trans-[PtBr(MDPP)(PPh3)2] (M = H2, Ni, Zn and Co), trans-[PtCl(H2DPP)(PPh3)2] and trans-[PtBr(NiDPPBr)(PPh3)2]. In all these structures, the free bases are virtually planar while the metallo derivatives adopt a hybrid of the ruffled and saddled conformations. Chapter 5 contains the initial studies of chiral palladioporphyrins, using three different types of chiral chelating diphosphine ligands. These chiral palladioporphyrins are readily prepared by oxidative addition of the Pd(0) precursor with bromoporphyrin. The asymmetry of the chiral ligand is detectable at the remote B-pyrrole protons in all the chiral complexes as eight doublets are observed in 1H NMR spectra. The chirality of these ligands in the porphyrin complexes induces circular dichroism in the region of the porphyrin electronic absorption. High optical activity is observed for the BINAP complexes.

Banana bunchy top virus (BBTV) is a circular, single-stranded (css) DNA virus that belongs to the genus Babuvirus in the family Nanoviridae. BBTV is responsible for the most devastating virus disease of banana known as "bunchy top", for which conventional control measures are generally ineffective. Genetically engineered resistance appears to be the most promising strategy to generate BBTV-resistant bananas but the success of this strategy is largely dependent upon the molecular characterisation of the target virus and knowledge of the virus life cycle, particularly the replication strategy. This PhD study was aimed at the molecular characterisation of the intergenic regions of BBTV, in order to complement the molecular information currently available and to potentially contribute to the development of transgenic resistance strategies against BBTV in banana. Three putative iterative sequences (iterons; GGGAC) previously identified in the BBTV intergenic regions were initially characterised. In order to determine their role in the binding of the master BBTV replication initiation protein (M-Rep), the putative iterons (F1 and F2 in the virion sense, and R in the complementary sense) were independently mutated in a BBTV DNA-6 greater-than-genome-length clone (1.1 mer). The DNA-6 1.1 mers (native and mutants) and the M-Rep-encoding component (DNA-1) were co-bombarded into banana (Musa spp. cv."Lady finger") embryogenic suspension cells and transient replication was evaluated by Southern hybridisation. Analysis of the DNA-6 replicative forms showed a significant decrease of approximately 41% for the F1 iteron mutant and 61% for the R iteron mutant in comparison with native levels. However, the mutation in the F2 iteron caused the most dramatic effect, decreasing replication to levels barely detectable by Southern hybridisation. These results suggest that the three iterons all play a role in BBTV replication, most likely as recognition and binding sites for the M-Rep, but that the F2 iteron appears to be the most important in replication. Following the observation that all BBTV isolates sequenced to date have identical iteron sequences, the extent to which the M-Rep would recognise, bind and initiate replication of heterologous components from geographically diverse BBTV isolates (the South Pacific and the Asian groups) was evaluated. Cross replication assays revealed that heterologous M-Reps from Fiji, Hawaii (South Pacific group) and Vietnam (Asian group) were able to initiate replication of the coat protein-encoding component (DNA-3) from the Australian BBTV isolate (South Pacific group). However, replication of DNA-3 from the Vietnamese isolate was not initiated by heterologous M-Reps from the two South Pacific isolates tested (Australia and Hawaii). These results suggest that a broad-range transgenic resistance strategy based on replication using Australian BBTV intergenic regions may be successful as this region will be recognised by the M-Reps from both Asian and South Pacific BBTV isolates. However, a Rep protein-mediated resistance strategy will more likely be specific to geographical isolates and, therefore, less suitable as a broad-range control strategy. To further characterise the BBTV intergenic regions and to gain a better understanding of the BBTV transcription process, the 5' untranslated regions (UTRs) of the major open reading frames (ORFs) associated with each of the six BBTV DNA components were mapped. In all cases, the transcription start sites were located 3' of a putative TATA box and the 5' UTRs varied in length from 23 nucleotides (DNA-6) to 5 nucleotides (DNA-3). Two potential transcription start sites (nt 84 and 87) were mapped for DNA-1, but whether these represent the transcription start sites of the two genes associated with DNA-1 remains to be determined. Two start sites were also associated with DNA-2 which is thought to be monocistronic. Whether one of these start sites is an artefact or whether they are due to natural sequence variability of BBTV is unknown. These results now enable us to define the transcribed regions of each BBTV DNA component and accurately predict their promoter regions in an attempt to gain a fundamental understanding of BBTV gene expression patterns.