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A dry-jet wet-spinning process developed industrially for the preparation of hollow fibre membranes suitable for gas separation applications, has been reproduced on a laboratory scale. Polysulphone hollow fibres were spun from a variety of solvents and their gas transport properties were characterized using equipment built during the course of the research. The phase inversion process of membrane formation was studied in order that the best morphological structure could be produced. The spinning parameters were studied to establish their influence on the fibre dimensions. Further relationships were then sought between the gas transport properties and the fibre dimensions and spinning parameters. The behaviour of the membranes to both single gases and gas mixtures was studied. Both the permeation rate constants and the separation factors determined from the mixture permeation were found to be lower than the values predicted from the single gas permeation experiments. A model was developed to help understand the competitive nature of the adsorption-diffusion process and explain the differences in values recorded from the single gas and mixture studies. Experiments aimed at improving membrane performance were based on modification of the already established polysulphone hollow fibre. Modification of the selective surface layer of the hollow fibre membranes was considered to be the best approach. Coating of the fibres, other than to repair damage to the skin layer, was found to result in too large a decrease in permeability. Sulphonation of the surface layer was achieved using sulphur trioxide, although little improvement in the membrane performance was recorded. The sulphonation experiment results were, however, sufficiently encouraging to recommend future work.

Muscle proteins are in a continuous state of recycling. This process involves a balance between synthesis and breakdown. These opposing processes dictate muscle protein gains and losses. Muscle hypertrophy occurs when synthesis exceeds breakdown. In order for the accretion of new muscle proteins, a chronic state of net positive muscle protein balance (synthesis> breakdown) is required. Resistance exercise is a potent stimulus of protein turnover and the combined effects of exercise and feeding have shown to be necessary for net protein anabolism. Resistance training has been reported to increase muscle strength and induce changes in skeletal muscle morphology. These positive strength adaptations include muscle fibre hypertrophy and a shift in fibre type from IJX to IIA. Previous investigations of resistance training-induced changes in muscle protein synthesis and fibre morphology have utilized cross-sectional or longitudinal, bilateral training designs. Thus, the purpose of this study was to investigate the effects of a progressive eight week unilateral leg resistance training program on skeletal muscle morphology, and resting and exercise-stimulated mixed muscle protein fractional synthesis rate (FSR). Eight young men performed two training sessions each week, and each session consisted of four sets of knee extension (KE) and four sets of leg press (LP) at 80% 1 repetition maximum (1 RM). Needle biopsies from the vastus lateralis muscle of the trained (T) leg were taken before and after training and analyzed for fibre composition, cross-sectional area (CSA), and myosin heavy chain (MHC) content. Muscle protein FSR was determined using a primed constant stable isotope infusion of [13C6]-phenylalanine in both the T and untrained (UT) legs. Training induced type IIX and IIA fibre hypertrophy (P <0.05) with no change for 1ype I fibre CSA. There was no significant change in histochemically determined fibre composition or MHC content. After training, 1RM strength of the T leg significantly increased compared to baseline values (P < 0.01). At rest, FSR was significantly elevated in the T versus the UT leg (P < 0.01). Following an acute bout of resistance exercise, which was performed at the same relative intensity (80% 1 RM) for the T and UT legs, FSR was greater in the UT versus the T leg (P < 0.01). There was a lower exercise-induced increase in muscle FSR in the T versus the UT leg compared to their respective resting values <T: P = 0.08, UT: P < 0.01). These data show that resistance training resulted in significant muscle fibre hypertrophy and elevated rate of muscle protein synthesis at rest. In addition, the acute response to resistance exercise was characterized by an attenuated rise in muscle protein FSR in the T versus the UT leg. We conclude that resistance training markedly attenuates the acute muscle protein synthetic response following resistance exercise, even when loads are matched at the same relative intensity. / Thesis / Master of Science (MS)

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Science): Vaal University of Technology / Here, we report the synthesis and characterization of silver (Ag) and silver selenide (Ag2Se) nanoparticles using the metal-organic route method. This method involves the reduction of selenium powder and silver nitrate in the presence of trioctylphosphine as a solvent. Tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) were used in the study as capping molecules. The optical properties of the as-prepared nanoparticles were studied using UV-Visible and photoluminescence spectroscopy (PL). Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) were used to study the structural properties. The effect of capping molecules and temperature were investigated on the growth of the nanoparticles. The prepared nanoparticles seem to depend on the reaction temperature were the increase in temperature led to an increase in particle sizes. The growth of the as-prepared TOPO-capped Ag2Se nanoparticles was influenced by temperature, this was evident when the temperature was increased, the nanoparticles evolved from sphere to hexagonal shape. TOPO-capped nanoparticles showed the tendency of agglomeration with increase in temperature compared to HDA-capped nanoparticles. The X-ray diffraction results showed peaks which were identified as due to α-Ag2Se body centered cubic compound for both TOPO/HDA-capped Ag2Se nanoparticles. Some evidence of impurities were observed in the XRD analysis and indexed to metallic silver. HDA-capped Ag nanoparticles were found to be affected by temperature variation. The prepared nanoparticles were characterized with UV-Vis spectroscopy and transmission electron microscopy. XRD analysis was not performed due to small yield obtained. The absorption spectra of HDA-capped Ag nanoparticles at different temperatures show a surface Plasmon resonance (SPR) band in the regions 418 - 428 nm. Uniform spherical shapes were obtained for both 130 and 190 °C and fewer particles were obtained at 160 °C. The synthesis of TOPO–capped Ag nanoparticles was unsuccessful since none of the particles were isolated from the solution due to its lower capping ability or it may be that TOPO is binding too strongly to Ag. The polymer nanofibres were electrospun using electrospinning technique. Parameters such as concentration and voltage were investigated. These parameters significantly affect the formation of fibre morphology. PVP and PMMA polymers were used for this study. The electrospun composite fibres were characterized using UV-Visible spectroscopy, scanning electron microscopy (SEM), Thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transformer infrared (FTIR) spectroscopy. The SEM results show that increasing the polymer concentration resulted in increased fibre diameters. Hence increasing the voltage decreases the fibre diameters. Ag2Se nanoparticles were incorporated into PVP and PMMA and electrospun using electrospinning to produce composite fibres. Their addition into PVP polymer fibres improved the fibre’s uniformity and further decreased their diameters. The SEM of composite fibres for PMMA is not shown. The absorption bands for PVP composites fibres show a blue shift from the pure Ag2Se nanoparticles, whereas the one for PMMA show a red shift from the pure Ag2Se nanoparticles. Both the composite fibres for PVP and PMMA show a blue shift from the bulk of Ag2Se. The XRD analysis of the composite fibres shows no significant effect upon addition of Ag2Se nanoparticles on the amorphous peak of the PVP polymer, whereas on the PMMA, it shows peaks which were due to the face centered cubic phase of Ag. The FTIR spectra of the composite fibres and pure polymers (PVP and PMMA) gave almost identical features. TGA curves show no significant effect on the thermal properties of the PVP polymer and its composites, however, on the PMMA composite fibres it show an increase in the thermal stability of the polymers upon addition of Ag2Se nanoparticles. The study was based on silver nanoparicles and its antibacterial activities. One of the synthetic challenges for silver nanoparticles is their solubility and yield. Selenide was introduced in the study to improve such shortcomings of silver nanoparticles and also for possible improved properties, chemical stability and increased activity against bacteria. The selenide group on the metal also provides stronger chemical interaction between the nanoparticles and the polymer. Therefore, the intension was to use these nanoparticles into polymer fibres for potential use in wound dressing.

Les objectifs principaux des travaux de recherche réalisés sont de caractériser, quantifier et corréler les changements induits lors du recyclage sur les fibres, la pâte et le papier. Pour ce faire, des techniques de caractérisation spécifique ont été utilisées telles que la chromatographie inverse d'exclusion stérique (ISEC), l'analyse mécanique dynamique (DMA), la microscopie électronique à balayage environnementale (ESEM), la microscopie à force atomique (AFM) et la tomographie à rayons X. Le racornissement des fibres à elle seule ne peut pas expliquer totalement la perte de résistance des fibres. Lors du recyclage la largeur des fibres, l'épaisseur des parois fibreuses, la courbure, le nombre de coudes et d'irrégularité diminuent. Les points faibles à l'intérieur de la paroi augmentent dans les premiers et les derniers cycles de recyclage. Les fibres deviennent plus dures et cassantes à l'état sec. Les forces capillaires et la friction de surface augmentent à l'état humide. La surface de liaison entre fibres dans le réseau fibreux diminue initialement à cause de la perte de la flexibilité des fibres à l'état humide et des éléments fins alors que l'augmentation qui suit peut être reliée au collapse du lumen. Comme la solidité des fibres de diminue pas, la baisse des caractéristiques mécaniques du papier pourrait être attribuée à la dégradation de la qualité des liaisons et plus particulièrement à une délamination partielle de la couche P/S1. / Incorporation of recycled fibres in high value paper products can reduce costand environmental loads. Papermaking potential of cellulosic fibres decreaseswith recycling. The phenomenon of fibre hornification during pressing anddrying is normally held responsible for the loss in strength. To study the impactsof recycling on pulp, fibre and paper properties some non conventionalcharacterisation techniques like fibre saturation point, X-rays microtomography,environmental scanning electron microscopic observations, atomic forcemicroscope (PeakForce QNM mode) and inverse size exclusion chromatography(ISEC) were used. In order to achieve good reproducibility of ISEC measurements,a semi-automatic column fabrication pilot system was built. Thetechniques were first validated on refining process before being applied to therecycling process. In this study, it was found that fibre hornification alone cannot fully explain loss in strength during recycling. The loss in strength is muchmore complex and it is required to understand the morphological and ultrastructural changes associated with recycling. Fibre width, cell wall thickness,curl, kink, irregularities decreased during recycling. Fibre became hard andbrittle in dry state. Number of weak points in the fibre wall were increasedinitially and in the later recyclings. The increase in wet breaking length indicatesincreased surface friction and capillary forces with recycling. Decreasein bonded area during first recycle may be caused by the loss of fines and fibreflexibility whereas the increase afterwards may be linked to the lumen collapse.The strength of fibres did not decrease with recycling as shown by zero-spanbreaking lengths therefore the quality of bond may be deteriorated. It wasthought that the partially delaminated P/S1 layers may be responsible for theloss of paper strength. It is suggested since the significant change is associatedwith the pressing and drying of never dried pulp therefore the drying processneeds to be revisited. The delaminated layer should be restored so as to increasethe recyclability of the recovered fibres for high value paper. Influenceof recycled pulp blends on physical properties of paper was also studied. It wasrevealed that small quantity of recycled pulp can be used without significantlyaffecting the mechanical strength properties.