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There are several key physical performance indicators (KPIs) in soccer, and these include lower limb power and reactive strength, which can be evaluated using a variety of jump assessments, e.g. countermovement jumps (CMJs) and drop jumps (DJs). These KPIs are thought to be underpinned by the physiological characteristics of the respective lower limb muscle-tendon units (MTUs). However, the influence of the gastrocnemius medialis (GM) MTU on power and reactive strength in elite youth soccer players (ESP) is currently unknown. Before assessing MTU properties and KPIs in ESP, it is important to understand the reproducibility of the respective assessment methods. In chapter 3, the aim was to identify the between-session reliability of all methodological techniques involved in the subsequent chapters. For this, 12 physically active, healthy, young men were recruited, the findings demonstrated all morphological properties of the GM muscle and GM tendon could be measured with high levels of reproducibility (coefficient of variation (CV)=1.2-6.6%; mean bias ratio (MBR)=1.00-1.09, ratio limits of agreement (RLoA)=1.04-1.22). Mechanical and material properties of the GM tendon could also be measured reliably (CV=2.6-17.3%; MBR=1.00-1.13, RLoA=1.08-1.80), however, the reproducibility of these techniques was slightly lower than for the morphological properties. Furthermore, a simplified method for calculating GM tendon mechanical/material properties proved reliable and agreed with the more comprehensive method, when assessed in 13 ESP and 12 non-athletes. This provides researchers/practitioners with a valid, reliable, and efficient method to monitor GM MTU properties when time is limited, e.g. when working with elite athletes. During jump-based assessments, peak power was measured more reliably during bilateral than unilateral CMJ, while reactive strength temporal variables during a DJ were more reliable than kinetic parameters. The second experimental study (chapter 4) aimed to determine whether the physiological characteristics of the GM muscle, as well as lower-limb power and reactive strength (the ability to develop maximal forces in minimal time while changing from an eccentric to concentric contraction) during CMJ and DJ, differed between ESP and recreationally active control participants (CON). A second aim was to investigate the relationship between GM muscle properties with lower limb power and reactive strength. ESP (17.4 ± 2.5) displayed a larger GM fascicle pennation angle (θp) compared to CON (14.3 ± 1.2, P<0.001), while projectile range and horizontal peak power during bilateral and unilateral horizontal CMJ were greater in the ESP. Furthermore, GM θp and cross-sectional area correlated with power generated in the vertical and horizontal plane of motion during unilateral vertical and bilateral horizontal CMJ, respectively. Perhaps surprisingly, GM muscle fascicle length and muscle volume both correlated inversely with power during bilateral vertical and horizontal jumps, although this may represent the differing biomechanical demands between unilateral and bilateral jumping tasks. The third experimental study (chapter 5) aimed to determine whether the mechanical and material properties of the GM tendon differed between ESP and CON, and whether GM tendon properties were related to lower limb power and reactive strength during CMJs and DJ. Tendon properties did not differ between ESP and CON but tendon elongation and strain correlated inversely with power during unilateral vertical CMJ, whilst higher force and vertical stiffness outputs were achieved during a DJ by stronger individuals with stiffer and larger GM tendons. Together with the findings from chapter 4, the results from chapter 5 suggest that specific physiological characteristics of the GM MTU could be deemed favourable for lower limb power and reactive strength capabilities. Through identifying (and perhaps developing) these characteristics in ESP, such KPIs in soccer players may be improved. The purpose of the fourth and final experimental study (chapter 6) was to investigate the effects of a 12-week in-season soccer training programme on GM MTU properties and jump performance in 14 ESP. Post-training, GM θp (pre-training: 18.0 ± 2.5 ; post-training: 17.2 ± 2.6 ; P=0.038), maximal tendon elongation (pre-training: 2.68 ± 0.58 cm; post-training: 2.30 ± 0.46 cm; P=0.019) and maximal tendon strain (pre-training: 12.8 ± 2.4 %; post-training: 11.1 ± 2.5 %; P=0.019) all reduced. Furthermore, projectile range during a unilateral horizontal CMJ increased from pre- to post-training (pre-training: 0.93 ± 0.15 m; post-training: 1.07 ± 0.12 m; P=0.001) but no other jump metrics changed. The physiological reasons for these changes are unclear but it is plausible that GM θp decreased to facilitate a faster shortening of the overall muscle in response to pitch-based training. Alternatively, it may have occurred in response to the limited progressive overload applied to the plantar flexors during in-season training (potentially leading to a detraining effect). Further, the reductions in tendon elongation and strain may have been due to a change in the material properties of the tendon (e.g. increased density of collagen fibrils) that did not quite translate to changes in stiffness or modulus. Crucially, however, these changes did not correlate (neither individually, nor in combination) with the change in projectile range during a unilateral horizontal CMJ, thus suggesting they did not contribute to this increase in jump performance. These results demonstrate that a 12-week period of in-season soccer training is not a sufficient chronic stimulus to elicit meaningful adaptation of the GM MTU to cause significant improvements in power and reactive strength during different jump-based assessments. In summary, this thesis demonstrates that the reproducibility of the techniques used to characterise GM MTU properties is generally acceptable to very good. Furthermore, specific GM MTU properties are related to lower limb power and reactive strength. Moreover, this thesis demonstrates that a three-month period of in-season soccer training is insufficient to elicit meaningful GM MTU adaptations required to improve physical performance. Therefore, whilst multiple factors contribute to influencing KPIs in ESP, this thesis presents novel information regarding the GM MTU and highlights potential physiological determinants that can be developed in youth soccer players.

Fluorite (CaF2) is a critical natural reserve and industrial fluoride recycling is of global importance. This work approaches the problem on two fronts. First, modification of a hydrometallurgical treatment system for spent potlining (SPL); a fluoride-rich, toxic, solid aluminium industry waste. Second, fluoride adsorption by metallated, porous, hydrophilic hypercrosslinked polymers (HHCPs). To ameliorate hydrometallurgical SPL treatment, an adsorption system is investigated, to selectively extract fluoride from a mixed leachate stream. A lanthanum-loaded chelating resin (La-MTS9501) is chosen for this purpose and its uptake characteristics are investigated. La-MTS9501 co-extracts fluoride and aluminium from simulated SPL leachate via adsorption of aqueous aluminium hydroxyfluoride (AHF) complexes, which chelate to the La centres via bridging fluoride or oxide ligands, with additional weaker interactions at higher leachate concentrations. Uptake was described best by multilayer and heterogeneous isotherm models. The theoretical maximum fluoride uptake capacity (qmax) was 145 mg·g-1 and the uptake followed pseudo second-order kinetics, with film-diffusion likely being rate-controlling. In dynamic column simulations, fluoride breakthrough was well-described by the Dose-Response model and dynamic loading capacity was 66.7 mg·g-1. Real SPL samples were leached via a two-step treatment using 1M NaOH with added H2O2, then 0.5 M H2SO4, which solubilised the majority fluoride content of numerous samples, of different mineral composition. The good dynamic column performance achieved with a simulant feed was retained with real SPL leachate. The fluoride and aluminium were selectively eluted from the column, using 1 M NaOH, with few problematic cocontaminants. Synthetic cryolite could potentially be attained from this feed by precipitation. A first-order technicoeconomic model suggested that, with some process optimisation, the enhanced hydrometallurgical system could offset its fixed-CAPEX within six years. Microporous hydrophilic hypercrosslinked polymers termed "HHCP1" and "HHCP2" were synthesised respectively from 2,2'-biphenol and bisphenol A monomers. These materials had high exchange capacities of up to 6.34 mmol·g-1 and unexpectedly broad pKa ranges. Polymers were loaded with calcium, to create fluoride selectivity, achieved by covalent bonding and unexpectedly by the formation of CaCO3, from adsorbed atmospheric CO2. Fluoride was extracted by conversion of the bound Ca species to CaF2. HHCP1 retained a high surface area after metallation and had a theoretical qmax of 267 mg·g-1. HHCP2 was converted to a surface-functionalised material and had lesser capacity, but faster uptake kinetics. Both polymers could be used in a dynamic column system and were selective in mixed anions uptake experiments, although phosphate was co-extracted. They could also be successfully regenerated in a two-step treatment, using HNO3, then re-metallation, over four cycles of use.

This thesis concerns the problem of whether a liberal state should - for liberal reasons - ban the wearing of the burqa in public. The core of the problem is that liberalism appears to pull in two opposed directions on this question. On the one hand, liberals strongly support religious tolerance and the burqa is seen by many, including most of those who wear it, as a religious commitment; and even if it is not a religious commitment it may still be a personal choice, and liberals strongly support enabling personal choice. On the other hand, liberals are committed to supporting equal rights and freedoms for both sexes, and the gender asymmetry of the burqa (women wear it, men don't) combined with the fact that habitually covering one's face in public is liable to cause disadvantages in personal, social and professional life, look like good reasons for opposing it; moreover liberals value personal autonomy, which may be compromised if the burqa is worn in response to cultural pressure. The issue thus exposes a tension within liberalism. A central element of my approach is the disentangling of a number of connected but separate strands of the problem. Thus I consider: different conceptions of liberalism and how they affect the response to the question; whether paternalism on grounds of welfare can be justified within liberalism and if so whether it would justify intervention in the specific case of the burqa; the value of personal autonomy within liberalism and whether a concern to safeguard or promote it could justify a burqa ban; the problem of adaptive preference and whether a socially influenced choice counts as a genuine preference; the role of multiculturalism in liberalism and to what extent it could justify exemptions; gender issues and feminism; the problem of coerced wearing of the burqa; and the problem of how likely it would be that a ban, even if justified in principle, would prove efficacious in achieving its end. The conclusion to the thesis is that banning the burqa in a liberal state is unlikely to be justified. It could not be justified in terms of the welfare or autonomy of the individual who voluntarily wears it. It could only be justified on the grounds of harm to others. It might, for example, theoretically be justified if coerced wearing of the burqa were widespread. This would be regrettable, however, as it would override the free choice of those who wore it voluntarily. Empirical evidence that such coercion was occurring would be necessary; and such a ban could only be justified if there were no other, equally efficacious and better targeted means of preventing coercion.