Cell-envelope associated and secreted proteins of Salmonella are integral for host-pathogen interactions, and for the induction of protective immune responses. An array of exported proteins of S. Brandenburg was identified through constructing an expression library using alkaline phosphatase gene technology. A partial digest of S. Brandenburg strain S59 was cloned into the vector pJEM11, and expressed in E. coli. The DNA inserts from randomly selected alkaline phosphatase positive clones were sequenced, and the sequences were analysed using public databases to find the ones that may play a role in host immune cell activation. The phase-1 flagellin (fliC) gene identified from an alkaline phosphatase positive phenotype was chosen for further studies. The complete nucleic acid sequence of the fliC gene was obtained by PCR amplification. The complete ORF, part of the variable region (V456) and region IV (V4) of the fliC gene were cloned into the pET14b vector for the expression of N-terminal histidine-tagged fusion proteins. The proteins were purified through metal affinity chromatography, and were evaluated for their humoral immunogenic properties by Western blotting with sera collected from 81 sheep naturally infected with S. Brandenburg. All 81 naturally infected sheep had IgG antibodies against recombinant FliC, V456, and V4 proteins. Furthermore, Western blotting of sera from 6 salvexinTM+B-vaccinated sheep (Trial 2004) had IgG antibodies against the 3 recombinant proteins. Whole blood cells of vaccinated sheep did not show interferon-gamma production upon stimulation with recombinant FliC and V456 proteins. Western blotting of sera from sheep vaccinated with salvexinTM and salvexinTM+B (Trial 1999), and those from rabbits vaccinated with S. Brandenburg, S. Hindmarsh and S. Typhimurium suggested that recombinant V4 contains epitopes specific for S. Brandenburg. Therefore, V4 was used to develop a novel indirect enzyme-linked immunosorbent assay (ELISA) for the detection of serum IgG antibodies in S. Brandenburg infected sheep. The ELISA showed a specificity of 100%, and a sensitivity of 93.8%. Furthermore, a new PCR assay was developed targeting rfbJ(B) gene in a single reaction, and genes invA, fliC and fljB in a multiplex reaction for the identification of S. Brandenburg from pure cultures. The sensitivity and specificity of the PCR assay was calculated to be 100%.

Published information on the structure and regulation of H. pylori promoters is limited. The work presented in this thesis describes the cloning and characterisation of promoter regions from a clinical isolate of H. pylori, and the development of an alternative, non-radioactive method for verifying the location of transcriptional start sites of bacterial promoters. H. pylori 4187E promoters were randomly cloned into the promoter-trap vector pKK232-8 in Escherichia coli DH5α using two sets of restriction enzymes. Vector pKK232-8 contains a promoterless chloramphenicol acetyltransferase (CAT) gene. Seventy-four promoter-containing clones were isolated from selective media based on their resistance to chloramphenicol. The strength of each promoter was analysed qualitatively, using chloramphenicol minimum inhibitory concentrations, and quantitatively, using CAT assays following exposure of the clones to pH 4 and pH 7. Selected promoter fragments were subcloned into the GFP reporter vector pFPV25, containing a promoterless gfp gene. The subclones were exposed to buffered LB broth at pH 4, 5, 6, 7 and 8, for varying lengths of time, to study acid-induced regulation of gene expression. Subclones were examined qualitatively, using visual examination of GFP fluorescence and fluorescence microscopy, and quantitatively, using flow cytometry following acid shock. DNA sequences were determined for 61 of the 74 H. pylori promoters, and sequence alignments with the published H. pylori strains (26695 and J99) were performed. The transcriptional start site of 27 H. pylori promoter fragments was experimentally mapped using a fluorescence-based primer extension protocol developed by our group. Potential -35 and -10 sequences were identified for each promoter, and a new consensus sequence for H. pylori promoters was proposed based upon these results. This study has considerably expanded knowledge of H. pylori promoter sequences and transcriptional start sites based on those which also function in E. coli. It has also revealed several H. pylori promoters which appear to respond to acid stress

Thesis (MSc (Genetics))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: South Africa is regarded as one of the top wine producing countries in the world. One of the threats to the sustainability of the wine industry is viral diseases of which Grapevine leafroll-associated virus 3 (GLRaV-3) and Grapevine virus A (GVA) are considered to be the most important and wide spread. Scion material is regularly tested for viruses; however scion material is often grafted onto rootstocks that have questionable phytosanitary status. Virus detection in rootstocks is challenging due to low and varying titres, but is imperative as a viral control mechanism. An additional viral control mechanism is the use of transgenic grapevine material which offers resistance to grapevine infection. The objective of this project was to establish a detection system using real time PCR (qPCR) techniques, to accurately and routinely detect GLRaV-3 and GVA in rootstock propagation material. qPCR would furthermore be used to perform molecular characterisation of transgenic plants containing a GLRaV-3 antiviral ΔHSP-Mut construct. A severely infected vineyard (Nietvoorbij farm) in the Stellenbosch area was screened throughout the grapevine growing season to investigate virus prevalence throughout the season and to determine the optimal time for sensitive virus detection. A large scale screening of nursery propagation material for GLRaV-3 infection was also conducted. The qRT-PCR results were compared to DAS-ELISA results to compare the efficacy and sensitivity of the two techniques. For the severely infected vineyard, the ability to detect GLRaV-3 increased as the season progressed towards winter. qRT-PCR was more sensitive and accurate in detecting GLRaV-3 than DASELISA, as the latter technique delivered numerous false positive results later in the season. The best time to screen for GLRaV-3 in the Western Cape region was from the end of July to September. For the nursery screenings, our qRT-PCR results were compared to the results of the DAS-ELISA performed by the specific nurseries. No GLRaV-3 infection was detected in the specific samples received from the two different nurseries. The results for all the samples correlated between the two techniques. This confirms that the propagation material of these nurseries has a healthy phytosanitary status with regards to GLRaV-3. However, the detection of GVA in the severely infected vineyard yielded inconsistent results. Detection ability fluctuated throughout the season and no specific trend in seasonal variation and virus titre fluctuation could be established. The highest percentage of GVA infected samples were detected during September, April and the end of July. Previously published universal primers were used for the detection of GVA, but further investigation indicated that they might not be suitable for sensitive detection of specific GVA variants present in South Africa. Vitis vinifera was transformed with a GLRaV-3 antiviral construct, ΔHSP-Mut. SYBR Green Real time PCR (qPCR) and qRT-PCR were utilised as alternative methods for molecular characterisation of transgenic plants. The qPCR and Southern blot results correlated for 76.5% of the samples. This illustrated the ability of qPCR to accurately estimate transgene copy numbers. Various samples were identified during qRT-PCR amplification that exhibited high mRNA expression levels of the transgene. These samples are ideal for further viral resistance studies. This study illustrated that the versatility of real time PCR renders it a valuable tool for accurate virus detection as well as copy number determination. / AFRIKAANSE OPSOMMING: Suid Afrika word geag as een van die top wyn produserende lande ter wereld. Die volhoubaarheid van die wynbedryf word onder andere bedreig deur virus-infeksies. Grapevine leafroll associated virus 3 (GLRaV-3) en Grapevine virus A (GVA) is van die mees belangrike virusse wat siektes veroorsaak in Suid-Afrikaanse wingerde. Wingerd bo-stok materiaal word gereeld getoets vir hierdie virusse, maar hierdie materiaal word meestal geënt op onderstokmateriaal waarvan die virus status onbekend is. Virus opsporing in onderstokke word egter gekompliseer deur baie lae en variërende virus konsentrasies, maar opsporing in voortplantingsmateriaal is ‘n noodsaaklike beheermeganisme vir virus-infeksie. Die doel van die projek was om ‘n opsporingsisteem te ontwikkel via kwantitatiewe PCR (qPCR) tegnieke vir akkurate en gereelde toetsing van GLRaV-3 en GVA in onderstokmateriaal. qPCR sal ook verder gebruik word vir molekulêre karakterisering van transgeniese plante wat ‘n GLRaV-3 antivirale ΔHSP-Mut konstruk bevat. ‘n Hoogs geïnfekteerde wingerd was regdeur die seisoen getoets om seisoenale fluktuasies in viruskonsentrasie te ondersoek en om die optimale tydstip vir sensitiewe virus opsporing te bepaal. ‘n Grootskaalse toetsing van kwekery voortplantingsmateriaal vir GLRaV-3 infeksie was ook uitgevoer. Die qRT-PCR resultate is met die DAS-ELISA resultate vergelyk om die effektiwiteit en sensitiwiteit van die twee tegnieke te vergelyk. Vir die hoogs geïnfekteerde wingerd het die GLRaV-3 opsporing toegeneem met die verloop van die seisoen tot en met winter. qRT-PCR was meer sensitief en akkuraat as DAS-ELISA in die opsporing van GLRaV-3, weens verskeie vals positiewe resultate wat later in die seisoen deur die laasgenoemde tegniek verkry is. Die beste tyd om vir GLRaV-3 te toets is vanaf einde Julie tot September. Tydens die kwekery toetsings was qRT-PCR resultate met die DAS-ELISA resultate van die spesifieke kwekerye vergelyk. Geen GLRaV-3 infeksie was waargeneem in die spesifieke monsters wat vanaf die kwekerye ontvang is nie. Die resultate van die twee tegnieke het ooreengestem vir al die monsters wat v getoets is. Dit het bevestig dat die voortplantingsmateriaal van hierdie kwekerye gesonde fitosanitêre status met betrekking tot GLRaV-3 gehad het. Die opsporing van GVA in die geïnfekteerde wingerd het egter wisselvallige resultate gelewer. Opsporing van die virus het ook regdeur die seisoen gefluktueer en geen spesifieke neiging in seisoenale opsporingsvermoë kon gemaak word nie. Die hoogste persentasie GVA geïnfekteerde monsters was waargeneem tydens September, April en die einde van Julie. Voorheen gepubliseerde universele inleiers was gebruik vir die opsporing van GVA, maar verdere ondersoeke het getoon dat hierdie inleiers nie noodwendig geskik is vir sensitiewe opsporing van GVA variante wat teenwoordig is in Suid-Afrika nie. Vitis vinifera was getransformeer met ‘n GLRaV-3 antivirale konstruct, ΔHSP-Mut. SYBR Green Real time PCR (qPCR) en qRT-PCR was ingespan as alternatiewe metodes vir molekulêre karaterisering van transgeniese plante. Die qPCR en Southern-klad resultate het ooreengestem vir 76.5% van die monsters. Dit illustreer die vermoë van qPCR om akkurate kopie-getalle van transgene te bepaal. Verskeie plante is geïdentifiseer tydens qRT-PCR amplifisering wat hoë vlakke van transgeen mRNA uitdrukking getoon het. Hierdie monsters is ideaal vir verdere virus weerstandbiedendheids studies. Hierdie studie het die veelsydigheid van real time PCR bewys en getoon dat dit ‘n kosbare tegniek is vir akkurate virus opsporing sowel as kopie-getal bepaling.

Le "gold-standard" du traitement chirurgical des scolioses est l'arthrodèse, qui consiste, à l'aide d'une instrumentation adaptée, à corriger et redresser les déformations scoliotiques, puis fusionner les vertèbres du segment pathologique afin de consolider la correction réalisée. Cette fusion entraine la destruction de la biomécanique physiologique du rachis, en supprimant sa mobilité et sa croissance. Les travaux réalisés dans le cadre de cette thèse portent sur le développement et la validation d'un nouveau concept d'instrumentation rachidienne ayant pour objectifs de réduire voire d'arrêter l'évolution des déformations rachidiennes, en conservant croissance et mobilité. Ce nouveau dispositif a nécessité une étude biomécanique large, partant du concept nouveau de cet implant, passant par la mise au point d'une méthodologie expérimentale, la conception et la réalisation de prototypes, puis leur validation à travers des études numériques, mécaniques, tribologiques et in vivo sur gros animal. La caractérisation in vitro du dispositif porte sur des essais mécaniques de caractérisation de matériau et des essais tribologiques de caractérisation du frottement. La caractérisation in vivo consiste en deux études menées sur gros animal, le modèle de porc Landrace, une première sur l'étude de l'arrachement de vis pédiculaires, puis une seconde, de validation de concept, avec 2 mois d'implantation du montage. Les premières conclusions tirées de ces travaux sont positives quant au bon fonctionnement du système. Des études en cours et à venir permettront de compléter ces résultats, et de valider le système dans son ensemble, afin de permettre sa future mise sur le marché. / The "gold standard" of surgical treatment of scoliosis is arthrodesis, which, with an appropriate instrumentation, corrects and straightens the deformities and fuses the vertebra of the pathologic segment to consolidate the correction. This fusion leads to the destruction of the physiological biomechanics of the spine, destroying growth and mobility. The work done in this thesis focuses on the development and validation of a new concept of spinal instrumentation which objectives are to reduce or even stop the development of spinal deformities, maintaining growth and mobility. This device is composed of materials used in new ways, leading to friction issues that do not exist in the current spinal systems. Thus, the system required a large biomechanical study, starting from the new concept of this implant, carrying on the development of an experimental methodology, designing and prototyping and then validation through numerical, mechanical, tribological and large animal in vivo studies. In vitro characterization of the device involves characterization of material through mechanical tests, and characterization of the tribological behavior of the system. In vivo characterization consists of two studies on large animal, the Landrace pig model : a first one on pedicle screws pullout, and a second one with 2 months of implantation, to validate the concept. The initial findings from this work are positive about the correct behavior of this system. Ongoing and future studies will complement those results, and validate the system as a whole, to allow future marketing.

The recent application of semiconductor materials, such as GaN, to power electronics has led to the development of a new generation of devices, which promise lower losses, higher operating frequencies and reductions in equipment size. The aim of this research is to study the capabilities of emerging GaN power devices, to understand their advantages, drawbacks, the challenges of their implementation and their potential impact on the performance of power converters. The thesis starts by presenting the development of a simple model for the switching transients of a GaN cascode device under inductive load conditions. The model enables accurate predictions to be made of the switching losses and provides an understanding of the switching process and associated energy flows within the device. The model predictions are validated through experimental measurements. The model reveals the suitability of the cascode device to soft-switching converter topologies. Two GaN cascode transistors are characterised through experimental measurement of their switching parameters (switching speed and switching loss). The study confirms the limited effect of the driver voltage and gate resistance on the turn-off switching process of a cascode device. The performance of the GaN cascode devices is compared against state-of-the-art super junction Si transistors. The results confirm the feasibility of applying the GaN cascode devices in half and full-bridge circuits. Finally, GaN cascode transistors are used to implement a 270V - 28V, 1.5kW, 1 MHz phase-shifted full-bridge isolated converter demonstrating the use of the devices in soft-switching converters. Compared with a 100 kHz silicon counterpart, the magnetic component weight is reduced by 69% whilst achieving a similar efficiency of 91%.

Ultra high performance fibre reinforced concrete (UHPFRC) is a relatively new fibre reinforced cementitious composite and has become very popular in construction applications. Extensive experimental studies have been conducted, demonstrating its superior properties such as much higher strength, ductility and durability than conventional fibre reinforced concrete (FRC) and high performance concrete. However, the material's damage and fracture mechanisms at meso/micro scales are not well understood, limiting its wider applications considerably. This study aims at an in-depth understanding of the damage and fracture mechanisms of UHPFRC, combining microscale in-situ X-ray computed tomography (µXCT) experiments and mesoscale image-based numerical modelling. Firstly, in-situ µXCT tests of small-sized UHPFRC specimens under wedge splitting loading were carried out, probably for the first time in the world, using an in-house designed loading rig. With a voxel resolution of 16.9µm, the complicated fracture mechanisms are clearly visualised and characterised using both 2D images and 3D volumes at progressive loading stages, such as initiating of micro-cracks, arresting of cracks by fibres, bending and pulling out of fibres and spalling of mortar at the exit points of inclined fibres. Secondly, based on the statistics of pores in the µXCT images obtained for a 20mm cube specimen, an efficient two-scale analytical-numerical homogenisation method was developed to predict the effective elastic properties of the UHPFRC. The large number of small pores were first homogenised at microscale with sand and cement paste, using elastic moduli from micro-indentation tests. 3D mesoscale finite element models were built at the second scale by direct conversion of the µXCT images, with fibres and large pores were faithfully represented. The effects of the volume fraction and the orientation of steel fibres on the elastic modulus were investigated, indicating that this method can be used to optimise the material micro-structure. Thirdly, 3D mesoscale finite element models were built for the specimen used in the in-situ µXCT wedge splitting test, with embedded fibre elements directly converted from the µXCT images. The fracture behaviour in the mortar was simulated by the damage plasticity model available in ABAQUS. Finally, 2D mesoscale finite element models were developed to simulate the fracture behaviour of UHPFRC using cohesive interface elements to simulate cracks in the mortar, and randomly distributed two-noded 1D fibres and connector elements to simulate the pull-out behaviour of fibres. This approach offers a link between the fibres pull-out behaviour and the response of the whole composite at the macroscale, thus it can be used to conduct parametric studies to optimise the material properties.

La transduction électrostatique est utilisée depuis plusieurs décennies dans les fréquences du domaine audible, principalement sous la forme de microphones membranaires. La transposition du même principe de transduction, mais dans un domaine de fréquence au-dessus du MHz, et par l’utilisation de dispositifs micro-usinés, c'est-à-dire produits à l’aide de technologies de photolithographie, a été proposée à partir de la fin des années 1990. Ces transducteurs, désignés sous l’acronyme cMUT (capacitive micromachine ultrasonic transducers), se composent d’un assemblage de transducteurs élémentaires, chacun possédant une partie mobile conventionnellement appelée diaphragme ou membrane, actionnée par la pression électrostatique. Cette thèse s’inscrit dans le développement de transducteurs de ce type destinés au domaine de l’imagerie médicale ultrasonore. Ce secteur d’application utilise actuellement des transducteurs basés sur des céramiques (ou, dans certains cas précis, des polymères) piézoélectriques. Le cMUT est intéressant dans certains sous-domaines d’application des ultrasons médicaux en raison de sa bonne adaptation à une production en grande série, de son intégration plus facile avec des éléments électroniques, de son faible échauffement et de l’absence de matériaux toxiques dans son processus de fabrication. La partie théorique de cette thèse repose sur une approche de modélisation par différences finies. Un modèle basé sur la théorie des plaques minces est développé pour prendre en compte la mécanique du transducteur élémentaire cMUT (c'est-à-dire d’un seul diaphragme). Ce modèle est ensuite complété par l’intégration de l’effet d’un chargement acoustique par un fluide. De façon à modéliser un transducteur entier, il est nécessaire de prendre en compte le couplage acoustique existant entre les différentes membranes. Pour rendre cela possible, un circuit équivalent, permettant de réduire chaque membrane à un système à un seul degré de liberté, est développé. Il est validé en le comparant au modèle de différences finies dans des cas où celui-ci peut être utilisé. Les travaux expérimentaux ont fait appel principalement aux deux techniques de caractérisation suivantes : les mesures d’impédance électrique, et les mesures de déplacement effectuées par interférométrie laser. Ces mesures ont été utilisées dans une double optique. D’une part, dans un objectif de caractérisation, ils ont permis de vérifier la fonctionnalité des dispositifs fabriqués et d’évaluer leurs performances. D’autre part, en comparant différentes configurations entre elles, ils ont rendu possible une validation expérimentale du modèle qui a été mis au point. / Electro-acoustic transduction based on electrostatic force has a long history in the range of audible frequencies, mainly as membrane-based microphones. Starting in the late 1990’s, it has been proposed to use the same principle in the multi-MHz frequency domain, thanks to micro-machined devices – meaning they’re produced through lithography technology. Such transducers, known as cMUT for capacitive micromachine ultrasonic transducers, are made of an assembly of elementary vertically mobile cells, usually designated as membranes, driven by electrostatic force. This PhD work is part of the development of this kind of transducers designed for medical imaging applications. This area currently uses transducers based on piezoelectric ceramics (or piezoelectric polymers for some peculiar cases). CMUT is an interesting alternative for some subdomains of medical ultrasound applications, due to its volume production ability, its easier integration with electronic elements, its low heat dissipation and the absence of toxic materials.

Malgré l'intérêt suscité, l'exploitation de l'énergie hydrolienne accuse toujours un sérieux retard par rapport à d'autres ressoures renouvelables. Ce développement tardif s'explique d'une part par l'absence d'une méthodologie pertinente de quantification du potentiel hydrocinétique, d'autre part, par le milieu marin, jugé hostile, au sein duquel des phénomènes turbulents,appliquent des contraintes sur la structure des hydroliennes. Offrant une vision précise de l'écoulement et de son hétérogénéité spatiale et temporelle, la courantographie radar, présentée dans la première partie de cette thèse, constitue un outil puissant d'analyse de la dynamique de la marée. Inédite dans le domaine des énergies renouvelables, elle offre une alternative probante à la modélisation numérique, souvent privilégiée bien que générant des résultats contestables compte tenu de sa conceptualisation simpliste des phénomènes réels. L'étude d'impact d'un écoulement turbulent pleinement développé sur la performance énergétique de prototypes d'hydroliennes de type Darrieus constitue la seconde partie de cette thèse. L'analyse spectrale des signaux temporels de vitesse de courant a permis de révéler les propriétés scalaires de l'écoulement. La caractérisation multi-échelle a montré que l'écoulement est animé par un processus dynamique de brisures successives des structures fluides imbriquées de taille allant de l'échelle d'injection à l'échelle de diffusion moléculaire. Enfin, le partitionnement en échelles dynamiques de la turbulence des spectres de vitesse et de puissance générée par l'hydrolienne a mis en évidence une certaine similarité entre la taille des structures tourbillonnaires qui régissent l'écoulement et les dimensions de la turbine. / Despite the growing interest , the use of tidal energy still lags far behind other renewable resource. This delayed development can be explained, on the one hand, by the absence of a relevant methodology for quantifying the hydrokinetic potential and, on the other hand, by the hostile marine environment, in which turbulent phenomena apply constraints on the structure of marine current turbines. The use of High Frequency Radar, presented in the first part of this thesis, provides a powerful tool for analyzing tidal dynamics and its spatial and temporal heterogeneity. Never used in the fields of renewable marine energy, it offers a convincing alternative to numerical modeling which is often chosen although generating questionable results because of simplistic conceptualization of real phenomena. The second part of this thesis is the study of the impact of a fully developed turbulent flow on the performance of a Darrieus-type turbine prototypes. The spectral analysis of the current velocity time series revealed the scalar properties of the flow. Multiscale characterization showed that the flow is driven by a dynamic process of successive breaks of fluid structures of size ranging from the injection scale to the molecular diffusion scale. Finally, the dynamical scaling of the turbulence of the velocity and power spectra generated by the marine current turbine has revealed a certain similarity between the size of the eddies structures that govern the flow and the dimensions of the turbine.

Used lead-acid batteries are the main raw material in secondary lead production. Technologicalprogress in the car industry, have raised concerns regarding the lead-acid battery’s leading positionas electrochemical storage system in the future. However, the lead-acid battery industry isadvancing with innovations, such as hybrid and micro-hybrid vehicles, and is believed to have acontinued important role in the rechargeable battery market. Lead is one of the most investigatedmetal due to concerns from society regarding the negative effect on human health and theenvironment. Consequently, that has led to tighter controls and regulations of the lead processingindustry which, in turn, has led to technological improvement concerning design and operation ofthe lead processing plants. Used lead-acid batteries have a complex composition with a variety ofcomponents made of lead (i.e., metallic, oxide or sulphate) and non-lead materials (plastics andelectrolyte). Traditionally, battery recycling is done without separating those components.However, to optimise the use of resources and decrease the environmental impact of secondarylead production, a pre-treatment step to the batteries recycling is desired. The pre-treatment iscomprised of breaking the batteries and separation of the battery components. The aim of the present thesis, was to study the components of a used lead-acid battery, which willbe the outgoing material of a future plastic separation plant at Boliden Bergsöe, and their effect onthe process. Furthermore, the study aimed at investigating the possibilities to adjust the feedcomposition for further process optimisation and improvement of the process quality in terms ofenergy usages and environmental impact. This was done by characterise, through qualitative andquantitative composition and mass distribution, the fractions in a used lead-acid car battery. Four lead-acid car batteries were provided for dismantling to study mass distribution, and toliberate the components for further analysis. The analytical techniques used in this study werequalitative and quantitative (Rietveld) XRD analysis, SEM-EDS and TGA. The result showed thatoverestimated amount of battery separators (PE) has been used at production planning in energyandemission calculations, which can cause financial losses due to overpaid emission tax. The pastefraction showed a large variation in mass between the studied batteries and consists mostly ofPbSO4. Large variation in the paste mass may cause uneven sulphur emission from smelter.Consequently, this reinforces the need for implementation of the separation of the battery feed fora better control of the paste addition to the smelter. When PE decomposes in the shaft furnace the remaining ash will mainly consist of silica, whichwill affect the sulphur uptake in the shaft furnace. The large content of silica leads to a lower energycontribution to the process; however, a lower content of hydrocarbons leads to lower CO2emissions. If a desulphurisation of the pastes would be implemented, it is believed to affect theprocess through a decreased need of coke and iron. A reduced usage of coke and iron would lowerthe production costs and lead to decreased CO2 emissions. A desulphurisation will also decreasethe lead sulphate content in the feed, thus lead to better control of the sulphur emissions. This study provides additional support and further insight into composition and mass distributionof the components in a lead-acid battery. Furthermore, the study indicates possible impact of thefuture separation on the new feed properties and on the subsequent processing.

Chapter 1 outlines the aim of the study, research methodology, delimitation of scope and the definition of some terms. This is followed by a list of Zulu short stories which Ntuli has already contributed. His other contributions in circles outside the writing of fiction are also acknowledged. Finally, tribute is paid to some contributions made by Ntuli as an endeavour to uplift the standard of Zulu writing. In Chapter 2 plot structure is discussed. This is followed by an in-depth semiotic analysis of some short stories. Chapter 3 deals with the different narration techniques employed by the author in his short stories. Chapter 4 differentiates between actors and characters. Different methods of character portrayal are investigated. Chapter 5 concludes this dissertation by summarising the main finding of this study. It also brings forth some conclusions with regard to literary merit of Ntuli's short stories and his contribution to Zulu literature. / African Languages / M.A. (African Languages)