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This thesis explores representations of British youth culture and adolescent identity formation in the ‘first generation’ (seasons 1-2) of the British television teen drama Skins (2007-8). Like its peers in the Teen TV genre, Skins focuses on normative teenage angst and rebellion that results in ‘naughty behavior’: sex, drug and alcohol use, and conflict with and alienation from parents. Skins sets itself apart from genre standards by heightening and glamorizing the way these behaviors are visually depicted. Furthermore, the characters experience very few substantial consequences or repercussions from parents or other authority figures, but rather repercussions come from within their own close-knit group. The primary source of tension in the series occurs during the moments when the group of friends challenge the cultural, biological and ideological constraints under which they find themselves when their preoccupied, self-involved, neglectful, and otherwise overbearing parents directly contribute to the conditions that fuel their excessive ‘naughtiness.’ The series creators, writers, producers and actors promote Skins as an authentic representation of teenage experience and this thesis ultimately seeks to explore the implications of this representation in order to gain a better understanding of British youth culture in the new millennium.

This thesis is a use-wear study that deals with microwear on stone endscrapers used on one worked material: animal skins. The first part of the study defines and describes the process of rendering freshly skinned pelts into functional leather or rawhide products, addressing confusing terminology found in the literature as well. Problems with past use-wear experiments dealing with animal skins are also confronted and explained. The second part of the study examines endscrapers used to flesh and dehair bison hides and compares the use-wear traces left on the tool edge by each activity. This suite of characteristics is then compared to those found on an assemblage of Clovis-age scrapers from the Gault site in central Texas.

This thesis is a use-wear study that deals with microwear on stone endscrapers used on one worked material: animal skins. The first part of the study defines and describes the process of rendering freshly skinned pelts into functional leather or rawhide products, addressing confusing terminology found in the literature as well. Problems with past use-wear experiments dealing with animal skins are also confronted and explained. The second part of the study examines endscrapers used to flesh and dehair bison hides and compares the use-wear traces left on the tool edge by each activity. This suite of characteristics is then compared to those found on an assemblage of Clovis-age scrapers from the Gault site in central Texas.

A polarimetric method for monitoring the rate of soluble collagen breakdown by collagenase enzyme action has been developed. The method represents an extension of previous physicochemical techniques based on viscometry, but is simpler and easier to carry out, particularly in the case of reaction rate studies. The method was developed arising from reports of collagenase activity measurement on inappropriate substrates such as gelatin, modified collagens and synthetic polypeptides. The optical method depends on measurement of the loss in optical rotation in solutions of soluble calfskin collagen resulting from initial enzymic cleavage of the collagen trip1e-helix, followed by spontaneous unwinding of the resultant unstable helical fragments. Specific assay conditions were chosen to ensure that the loss in optical rotation following enzymic cleavage was rapid and complete. The method is specific since in the absence of collagenase, non-specific proteinases produce only a limited decrease in solution optical activity. The method has also been compared with established physicochemical assay techniques and compares favourably with both viscometric and titrimetric collagenase assays. The availability of a rapid, sensitive and quantitative procedure for measurement of collagenase activity provides a convenient means for detecting the presence of collagenase in solution and examination of hide bacterial cultures for collagenase production. In addition, a study of biocidal compounds of potential interest in hide preservation for possible inhibitory effects on collagenase is conveniently carried out with the method. Fundamental research into synergistic action in enzymic hydrolysis of collagen is now possible, providing valuable insight into the mechanism of raw hide biodeterioration.

In the leather industry fungicides are often used for the protection of wet-blue leather. These fungicides are usually only sparingly soluble and are therefore formulated together with surfactants in order to increase their solubility and to ensure an even distribution over the surface of the hide after treatment. Solutions containing both fungicides and surfactant are complex. The nature of these solutions was investigated. By means of UV/Vis spectroscopy and viscometry it was shown that the surfactant and fungicides form micelles and mixed micelles in solution. The nature of these micelles and mixed micelles was dependent on the solution temperature as well as on the concentrations of the surfactant and fungicides. At the higher temperatures and concentrations transition to large, possibly rod-shaped, mixed micelles occurred. The interaction between the selected fungicides 2-(thiocyanomethylthio)benzothiazole and n-octyl-4-isothiazol-3-one with bovine skin collagen in the form of both limed and lightly chromed hide powder in the presence of the non ionic surfactant Triton X -100 was investigated. Fungicide uptake was determined by difference measurements on the float solutions at regular intervals during treatment. Binding was rapid with equilibrium being established within the first six hours even for the solutions with the highest surfactant concentration. Binding failed to follow a normal mass-action binding-type isotherm approaching a saturation limit, but increased continuously indicating a co-operative effect whereby binding site affinity actually increased with the amount of ligand bound. Binding was accompanied by a drop in the free surfactant in the solution at the higher biocide levels indicating the formation of complex mixed micelles which bind to the collagen fibres. The uptake and antifungal activity of commercial fomulations of the fungicides on chrome-tanned wet-blue leather was investigated at various treatment temperatures. At lower fungicide treatment concentrations, binding tended to follow a typical mass-action type binding isotherm, increasing slightly with temperature. At higher float concentrations, an inflexion point was apparent beyond which uptake showed a marked increase with concentration. This inflexion point, signifying a change in binding characteristics, occurred at progressively lower concentrations with increasing temperature. Antifungal activity in terms of storage periods to onset of fungal growth was determined on the wet-blue leather cuttings immediately after treatment and drainage and also on sample discs after exhaustive extraction of free fungicide using dichloromethane. Storage performance testing of the various treated wet-blue leathers was carried out by different methods. Residual protective periods showed a curvilinear increase with dosage offer and surface uptake. In the low dosage range treatment temperature had only a relatively slight effect in promoting uptake and improving storage protection. At higher dosages, the influence of temperature on uptake and storage protection was greater due to the increase in surface binding of the fungicides at the elevated temperatures. Only a portion of the fungicide uptake was recovered by direct solvent extraction of the treated wet-blue leather. Solvent extraction reduced storage margins. The storage response in relation to fungicide content was, however comparable after extraction, indicating that both irreversibly bound and physically associated fungicide offered effective protection. Results of the study provide further insight into the mode of interaction of fungicide emulsion dispersion with bovine skin collagen, and the importance of the emulsion dispersions and its stability in determining the uptake of fungicide.

The research presented in this thesis investigates the mechanical properties of candidate materials that could be used as a skin for a morphing wing. A morphing wing is defined as a wing that changes shape. Although engineers have been designing different morphing wing configurations, there has been limited research investigating materials that could be used as a skin for a morphing wing. Specifically, after investigating the different morphing wing abilities engineers at Virginia Tech are designing, criteria were determined for candidate materials. A suitable skin material for a morphing wing will have to be elastic, flexible, have high recovery, resistant to different weather conditions, resistant to abrasions and chemicals, and have a hardness number high enough to handle the aerodynamic loads of the aircraft while in flight. Using some of the preceding criteria, different materials were selected that are readily available in the commercial market. The materials tested were a type of thermoplastic polyurethanes, copolyester elastomer, shape memory polymer, or woven materials that are made out of elastane yarns. The first study determined the required forces to strain the material in a uniaxial direction. A test stand was designed with a gripping device to hold the material. By grounding one side of the material, the other side of the material was pulled using a winch. Using a force transducer and a string potentiometer the required forces and the amount the material was strained was recorded, respectively. Utilizing the same test stand, the amount the material recovered was also acquired. Also, by measuring how much the material necked the elongation ratio was calculated. The final test determined if the forces "relaxed" after being strained to a stationary position. It was found that each material performed differently, but some materials were definitely better suited for morphing wing material. The materials that were made out of thermoplastic polyurethanes, copolyester elastomer, and shape memory polymer required less force and were able to strain more, when compared to the woven materials. The second study determined if the material could be strained in a biaxial direction. The reason for this was for a better understand how the material would perform if the material was strained to an extreme condition. A test stand was designed using the same principles and components as the uniaxial test stand. The only difference was additional sensors were required to measure the force and strain along the other axis. Although a recovery analysis was warranted for the biaxial experiments, most of the materials test failed while being strained a small amount. Also, the material strained a lot less before ripping, when compared to the straining capabilities when only being strained in the uniaxial direction. After conducting the experiments, the results were similar to the uniaxial experimental results. In terms of required forces to strain the material, the thermoplastic polyurethanes and the copolyester elastomer required less force, when compared to the woven materials. The only advantage of the woven materials was they did not break. The final study determined how much the material deflected while being subjected to a pressure load before breaking. The test stand used an air compressor to supply a pressure load to the material, while a laser vibrometer measured how much the material deflected. A regulator was used to control the amount of pressure that was applied to the material. As the pressure load was increased, the material deflected more. The test stand also determined the maximum sustained pressure load the material could handle before breaking. After conducting all the experiments and analyzing the data, it was found woven materials are not suitable as a skin material. The reason air is allowed to pass through the woven material. Therefore, woven materials could not sustain the aerodynamic loads of an aircraft while in flight. The rest of the materials performed differently. Specifically if the material strained well and required less force while conducting the uniaxial and biaxial experiments, those materials could not sustain a high pressure load. Yet, the materials that did not strain well and required more force were able to handle a larger sustained pressure load. / Master of Science

Thesis (M.A. (African Language)) --University of Limpopo, 2012 / Refer to document

Hydrated amorphous silicon dioxide (Si02.nH-,O), or opal-A, is deposited naturally from seepage and runoff water as white or brown rock surface coatings, called 'skins', that often partly obscure rock paintings and engravings, but occasionally, a thin translucent silica skin can form a protective film over rock art. White lustrous silica skins, less than 1 mm thick, occur where seepage water regularly flows from bedding and joint planes, whereas much thinner brown skins form on the sides of boulders and cliffs where runoff water periodically flows. To find the degree of silica skin variability and to determine how climate and rock type affect the properties of silica skins I collected samples at seven Australian and two Canadian rock painting sites that were located in temperate, tropical and sub-arctic regions. The skins had developed on sandstone, quartzite, schist, gneiss and migmatite. I studied the effects of the skins on rock art stability, documented their compositions, textures and structures to establish their common properties, and searched for a way to date the silica which would provide an indication of the minimum age of the underlying art. 1 also made replication experiments to determine factors that influence the properties of artificial silica skins and the rates of their precipitation so that I could propose a mechanism for natural silica skin formation, and ascertain whether an artificial silica skin could act as a protective rock art conservation measure. I was able to subdivide the analysed samples into silica skin Types I, II and III on the basis of their colour (translucent, white or brown), composition (SiO2, Al2O3 and absorbed water contents) and texture (smooth vitreous or vermiform). I propose that silica skins initially begin to form on stable rock surfaces by a process involving a combination of evaporation- and ionic-induced polymerisation of silicic acid in seepage and runoff water. Condensation reactions, random clustering of small silica spheres and deposition of the resulting aggregates eventually produce a thin surficial silica film. Deposition of silica often traps micro-organisms that live in the damp seepage and runoff water zones, and these fossils in finely laminated skins enable the radiocarbon dating of silica deposition, and therefore the dating of rock paintings enclosed by silica. Micro-excavation of silica layers associated with rock art combined with accelerator mass spectrometry gave preliminary radiocarbon determinations that were either consistent with, or contradicted, prevailing opinions about the antiquity of the rock art at selected sites. Experiments using a laser technique for combusting fossilised microorganisms in finely laminated skins were unable to generate sufficient carbon for dating. Catalysis of a mixture of equal proportions of methyl-trimethoxy silane and water produces a translucent stable film that may be suitable as a consolidant, whereas other artificial silica skins made from silica glass and tetra-ethoxy silane develop microfractures on drying, and these are unsuitable as rock art consolidants.