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Acetaldehyde (AA) is a degradation product of poly(ethylene terephthalate) (PET). AA can migrate from the walls of a PET bottle into drinking water and cause an off-taste at very low concentrations. Currently anthranilamide (ATA) is added to PET to scavenge the AA and is able to remove up to 80% of the contaminant. However, ATA is a stoichiometric scavenger so there is scope for a more efficient technology to be developed that utilises catalytic scavengers. ColorMatrix owns a patent for catalytic AA removal technology that uses a hydrous zirconium oxide catalyst. In this study the claims made in that patent were examined and scrutinised, and alternative metal oxide catalysts were prepared and tested to determine if they could be more effective for AA removal. A laboratory testing protocol for testing the AA conversion activity of the metal oxide catalysts was developed that involved a gas-phase reactor equipped with online Gas Chromatography (GC) analysis. This reactor could be used to determine the suitability of samples for testing in PET at ColorMatrix in Knowsley. ColorMatrix have the capability to test the catalysts under application-like conditions because they have the apparatus to dry, extrude, and analyse the PET. The catalyst samples that were prepared in the laboratory were also subjected to a bevy of characterisation techniques in order to gain understanding regarding which physicochemical properties are most important for an effective AA removal catalyst. CeO2 catalysts were found to be the most active of the samples tested in this study. Alternative preparation methods, milling, and doping were among the routes that were explored to attempt to increase the efficiency of the CeO2 catalysts. The catalyst sample that achieved the greatest AA reduction in PET of 32%, was prepared using urea precipitation with a urea to metal nitrate molar ratio of 3:1. This project was half-funded by ColorMatrix/PolyOne and half-funded by the EPSRC through the Centre for Doctoral Training in Catalysis.

We study several aspects of the Möbius function, μ[σ, π], on the poset of permutations under the pattern containment order. First, we consider cases where the lower bound of the poset is indecomposable. We show that μ[σ, π] can be computed by considering just the indecomposable permutations contained in the upper bound. We apply this to the case where the upper bound is an increasing oscillation, and give a method for computing the value of the Möbius function that only involves evaluating simple inequalities. We then consider conditions on an interval which guarantee that the value of the Möbius function is zero. In particular, we show that if a permutation π contains two intervals of length 2, which are not order-isomorphic to one another, then μ[1, π] = 0. This allows us to prove that the proportion of permutations of length n with principal Möbius function equal to zero is asymptotically bounded below by (1−1/e) 2 ≥ 0.3995. This is the first result determining the value of μ[1, π] for an asymptotically positive proportion of permutations π. Following this, we use “2413-balloon” permutations to show that the growth of the principal Möbius function on the permutation poset is exponential. This improves on previous work, which has shown that the growth is at least polynomial. We then generalise 2413-balloon permutations, and find a recursion for the value of the principal Möbius function of these generalisations. Finally, we look back at the results found, and discuss ways to relate the results from each chapter. We then consider further research avenues.

Focusing attention onto the intended outcome or goal of a movement (an External focus of attention) has been shown to be more beneficial to the learning and performance of movements than focusing onto the components of the movement being carried out (an Internal focus of attention). In this thesis, four studies assessed the effects of attentional focusing strategies on the learning and execution of motor skills during different situations. Study 1 demonstrated that an internal focus of attention during a suprapostural pointing task resulted in degraded postural control as well as larger movements of the hand and arm. In Study 2 novices using an external focus were more accurate in a dart throwing task than those using an internal focus, but no different from a control condition. In Study 3 two experiments investigated the effects of attentional focuses on postural control at rest and whilst fatigued. Postural control was no better using external focus when compared to an internal focus at rest, but was better than baseline. When fatigued (localised and generalised), balance was significantly deteriorated using an external focus, but not when an internal focus was used. In two experiments during Study 4 novices carrying out a dart throwing task used different attentional focusing instructions during practice and later performance. During practice sessions in Experiment 4.1 and 4.2 accuracy was not affected by attentional focusing instructions. Using an external focus during performance resulted in significantly better accuracy than using an internal focus. In Experiment 4.2, novices who preferred an internal focus but used an external focus during performance performed less accurately than participants who preferred the external focus. Findings demonstrate that the benefits of an external focus of attention is evident in performance situations, whereas an internal focus may be beneficial whilst fatigued and is not detrimental during practice.

HIV-2 infected monocyte derived macrophages (MDM) at much lower efficiency compared to HIV-1 or to infection of PBMC. After a brief initial burst of replication, HIV-2 viral production was terminated. HIV-1 however rebounded cyclically in culture over a period of 20 days. Early entry events of HIV-2 in MDM were accommodated efficiently and replication could be restimulated with LPS indicating that HIV-2 enters a latent phase in MDM. The amino acid charge of the HIV-1 V3 loop is negatively correlated with macrophage tropism (Zhong et al., 1995), and I demonstrate that the HIV-2 V3 loop charge is also negatively correlated with MDM tropism, albeit weakly. This led me to investigate other determinants of HIV cellular tropism. An HIV-2 primary isolate that is unable to replicate in MDM was molecularly cloned (MCR) and the restriction (termed Lv2) mapped to virus env and gag (Schmitz et al., 2004). I show that a variety of primary HIV-1 and HIV-2 viruses are susceptible to Lv2 restriction. Lv2 is a post-entry, post-reverse transcription restriction to HIV infection. To incorporate a role for Env, which acts at the cell surface, a model where the Env delivers a susceptible Gag into a restrictive cellular compartment was developed (Schmitz et al., 2004). The compartmentalisation model of Lv2 was tested using compounds that affect endocytic pathways (hypertonic sucrose) and lipid rafts (Methyl- p-cyclodextrin) in restrictive cells. With these methods I show that restricted virus can be rescued from Lv2 if a lipid raft-dependent endocytic pathway is inhibited. Fusion of restricted virus into HeLa/CD4 cells containing a tailless CD4 that located outside lipid rafts was fully permissive. The restrictive pathway was further defined using dominant negative mutants that specifically inhibit defined endocytic pathways clathrin, caveolae and non-clathrin non-caveolae mediated. A role for an Arf6 non-clathrin non-caveolae mediated endocytic pathway in Lv2 restriction was demonstrated. Lastly, env swapped viruses demonstrate that delivery to the restriction pathway is Env dependent. In keeping with the Lv2 model, the unrestricted virus was unaffected by any of these treatments. Thus the route of entry, determined by the viral Env, can influence cellular tropism by avoiding intracellular blocks to infection. The saturable nature of Lv2 restriction was investigated. HIV-2 Env pseudotypes of El and N-tropic MLV pseudotypes saturated Lv2. This observation led me to investigate if human tripartite motif protein (TRIM) 5a and members of the human TRIM family of proteins, shown to restrict MLV, mediated Lv2. The TRIM family of proteins have been implicated in retroviral restrictions and even so far as to have broad anti-viral activity (Nisole et al., 2005). By choosing TRIM proteins with SPRY(B30.2) domains, and an RNA interference (RNAi) screening approach, TRIMs 1,18 and 34 were identified as having Lv2 restriction activity. These proteins are expressed in restrictive HeLa/CD4 cells but not in permissive ones, thus acting as intracellular determinants of retroviral cell-tropism.