Dissertation (LLM)--University of Pretoria, 2014. / lk2014 / Mercantile Law / LLM / Unrestricted

Ultra high temperature (UHT) method is a thermal heat treatment of milk that is able to destroy non- sporeformers and sporeformers. The UHT process uses a temperature of 135-140°C for 1-2 seconds. Bacillus sporothermodurans is the only known species whose spores are able to survive the UHT treatment. With companies having the disadvantage of not being able to increase the temperatures during milk processing as a result of negative sensory properties, a better understanding of the structure of B. sporothermodurans spores and how exactly B. sporothermodurans is able to survive such high temperatures has become of great importance in the dairy industry. The first objective of this study was to determine whether there was a genotypic difference in the structure of B. sporothermodurans spores between those strains isolated from UHT strains and those from other sources (i.e. raw milk, feed concentrate and silage). Due to the fact that B. sporothermodurans spores are becoming more widespread, other genetic tools were used to help confirm the presence of these strains and whether they have the heat resistant clonal gene, thereby confirming whether the spores are heat resistant (HRS) or not. Two recently isolated strains (i.e. F3 isolated from UHT milk in South Africa and QA1 isolated from UHT milk in Belgium) were identified using the general B. sporothermodurans method (BSPO PCR) and the more specific HRS-PCR method identifying the HRS clone. Thereafter the (GTG)5 PCR method was used to compare 9 B. sporothermodurans strains previously obtained from UHT milk or farm sources in different countries. Results showed that the two recently isolated UHT strains, QA1 and F3, had a close association shown by the (GTG)5 PCR patterns and were positive for the HRS clone. Results go on to show that the B. sporothermodurans strains of the HRS clone look to be primarily responsible for the production of heat resistant spores and that (GTG)5 PCR is a method that can be used to evaluate the genotypic differentiation of B. sporothermodurans strains. The second objective was to determine the effect of heat on the structure of Bacillus sporothermodurans spores. The spores of three B. sporothermodurans strains namely F3 (HRS strain isolated from UHT milk in South Africa), DSMZ 10599 (one of the first HRS strains isolated from UHT milk in Italy) and MB 1499 (a non HRS strain isolated from a feed concentrate in Belgium) were compared using various microscopic techniques. When observing the layers, an exosporial layer was present in all three strains. The second layer, the coat, showed to have multiple layers making up the spore coat. The first layer was the outer coat layer; the middle coat was made up of 4-5 lamellae layers and the last layer was the inner spore coat layer. A short, thick appendage like structure was observed in F3 developing from the middle coat layer. Differential scanning calorimetry was conducted on the B. sporothermodurans strain DSMZ 10599. The initial scan (thermogram from DSC) of DSMZ 10599 showed 3 transitions, one at 79°C, the second at 87°C and the third at 113°C. The initial peak was associated with the activation of the spores due to the heat. The other two endothermic peaks were most likely due to protein denaturation of the spore coat or cortex, or DNA unfolding in the spore core. The heat values were found to increase from the first to the last transition. UHT milk is heated to temperatures of up to 140°C and the DSC profile showed that spore death of strain DSMZ 10599 did not occur at this high temperature. The third objective was to determine the effects of H2O2 on the structure of B. sporothermodurans spores. The strains F3, DSMZ 10599 and MB 1668 were compared in terms of susceptibility to hydrogen peroxide. After 3 minutes, the exosporial and coat layer were completely degraded with significant swelling of the spore core. Rupture of the core of strains DSMZ 10599 and F3 occurred at 6 minutes. At 9 minutes, the core outer layer of F3 and MB 1668 was completely degraded however, not fully for DSMZ 10599. At 15 minutes the core was exposed to the environment however even though DSMZ 10599 core layer was still not completely degraded, the core was still exposed to the environment. It was concluded that (GTG)5 PCR is a method that can be used to evaluate the genotypic differentiation of B. sporothermodurans strains. When observing B. sporothermodurans phenotypically, for the first time, short appendage like structures were present protruding from the spore coat which may explain attachment to steel pipe surface resulting in post and cross contamination in UHT milk. A further investigation would be interesting to determine whether this species is able to produce a biofilm. It was also concluded that B. sporothermodurans spore structures do contribute to the resistance of heat and chemicals. It would be interesting to determine whether the damage done to the spore by heat is reversible. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Food Science / MSc / Unrestricted

In the pursuit of more accurate diagnostics of turbo machinery sophisticated rotor and bearing models are to be developed in order to better understand the dynamics of the rotor-bearing system. This study is concerned with such bearing models. Four distinct fluid models are developed: The first two have a viscous fluid formulation, where fluid dependencies enter the momentum equations primarily through the viscosity of the fluid. The last two have a viscoelastic fluid formulation where dependencies enter the equations through an additional differential constitutive relation. This constitutive relation is strongly coupled with the momentum equation. The dependencies included in the formulation of the fluid are: pressure, shear rate and temperature. The coupling of the fluid models is subject to the dependencies present in the formulation. Uncoupled, weakly coupled and strongly coupled formulations are compared in this work. The formulated models are solved numerically using the Finite Volume Method in the open source program OpenFOAM. These models were newly implemented in OpenFOAM as part of this study. The models are validated by comparing results with various known analytical solutions. A region of the bearing is subsequently analysed, where the dependencies of the lubricant are most prominent. In this region the influence of a weak and strong coupled formulation of the fluid dynamics in the oil film was considered. In this study it is shown that both weak and strong couplings influenced the fluid behaviour significantly. It is shown that when these dependencies are no longer isolated in the mere adjustment of fluid properties is inadequate to account for the influence of dependencies. The weak coupled formulation shows the difference between the coupled and uncoupled formulations. The weak coupling influence the fluid dynamics to the same extent as the pressure dependency in the region considered. The departure from the classical formulation is however observed to be uniform in the case of a weak coupling. The difference between the uncoupled and strongly coupled formulation was not as great as in the weakly coupled case. Although the difference was less, it was seen that the presence of the strong coupling was about 40% of that of the temperature dependency in the region considered. The change in flow, for the strong coupled formulation, was non-homogenous compared to the classical formulation. The influence of the coupling is therefore different in nature. The weak coupling changes the flow more than the strong coupling compared to the classical formulation. The strong coupling introduce a new characteristic to the fluid behaviour not seen with the weak coupled formulation. Lastly it is shown that in order to model the bearing adequately, the fluid model and the coupling of the governing equations are not trivial. Great care must be taken in both the fluid model used as well as the formulation of the coupled equations. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Mechanical and Aeronautical Engineering / MSc / Unrestricted

The creation of value in and for organisations and societies has become a major area of interest in the triple context environment of people, planet and profit. The role of communication in this process prompted this study, guided by the following fundamental research question: How can strategic communication management be conceptualised in a triple context environment, considering the shared expectations between top management and communicators about communication excellence, with specific reference to the business cycle and the communication cycle of the organisation? The study followed a grounded theory methodology (Strauss and Corbin) and was conducted in three phases of triangulation: Phase 1: Two literature cases were compiled and analysed. The first consisted of four slices of data, which guided the compilation of the second case (540 academic articles). The data were analysed through the hierarchical process of open coding, axial coding and selective coding, which resulted in a preliminary framework for the grounded theory. Phase 2: Six empirical field studies were conducted by means of desk research and interviews. The data were analysed by using the hierarchical coding process with the aim of developing the concluding framework. Phase 3: The substantive grounded theory was compared with the Excellence theory, while a case study of best practice, illustrating the pragmatic applicability of the theory, was also presented. The integrative strategic communication management theory developed in this research, illustrates the core considerations in the communicative ambit of the organisation as it functions in the triple context environment. In the demanddelivery linkage of shared expectations between top management and communicators, the management categories of a sustainability orientation, inclusive corporate governance approach, and integrative strategic management and strategy development were identified as causal conditions for the phenomenon of the conceptualisation of strategic communication management in a triple context environment. In this context, the communication management categories of conscious internal and external communication and mutually beneficial stakeholder relationships serve as intervening conditions for reflective stewardship when facilitating core competencies and dynamic capabilities in the co-creation of value. The outcomes of this process are a good corporate reputation and communicative capacity built through communicative currency, capital, equity and value. / Thesis (PhD)--University of Pretoria, 2014. / lk2014 / Communication Management / PhD / Unrestricted

The industry of wireless digital communications has matured since the 1970s with the introduction of cellular technology, to the present rollout of fourth generation infrastructure. The discovery and refining of technology such as orthogonal frequency division multiplexing (OFDM), code division multiple access (CDMA) and later multiple-input multiple-output (MIMO) techniques has set the stage for the current and future high capacity broadband wireless cellular networks. A number of organisations have developed standards for wireless communication technologies, most notably the Third Generation Partnership Project with the Long Term Evolution series of standards and the Institute of Electrical and Electronics Engineers (IEEE) with its IEEE 802 series of standards. This work aims to contribute to the afore mentioned field of research by amalgamating three key technologies into a wireless communication system. The methodology adopted has centred on orthogonality with the utilisation of OFDM, CDMA employing completely orthogonal complementary codes and MIMO techniques. OFDM provides a reduced complexity means for managing multipath environments by taking advantage of the fast Fourier transform (FFT) algorithm for modulation and demodulation. Furthermore the cyclic rotation scheme applied to the orthogonal complete complementary codes allows the use of spread spectrum technology without the inherent rate loss while providing multiple access. The recent advances in multiple antenna communication technology have led to the development of two branches in the field. The first of these was the introduction of the spatial multiplexing concept which increases the system capacity and the second was the development of many diversity achieving spatial coding techniques. Of the diversity achieving techniques orthogonal space-time block codes (OSTBC) are most notable due to their linear detectability. The performance of two communication systems has been evaluated through simulation. Both employ the multi carrier CDMA based on the cyclically rotated complete complementary codes however the fundamental difference between them is the spatial coding. Spatial multiplexing and OSTBCs have been utilised with a matrix algebraic framework description unifying both. The spatial multiplexed signals are detected with a non-linear sphere decoder and the OSTBC data is detected linearly. The results have shown that the systems achieve the expected diversity orders in flat fading conditions. The OSTBC system achieves added gains in multipath conditions due to the spread spectrum coding. The codes provide multiple access as well as extract added multipath diversity that would otherwise be unavailable. Interestingly, both systems were unaffected by Doppler since perfect channel state information was assumed and the spreading was performed in frequency domain. / Dissertation (MEng)--University of Pretoria, 2014. / lk2014 / Electrical, Electronic and Computer Engineering / MEng / Unrestricted

Diabetes mellitus is a chronic metabolic disease caused by insufficient insulin production by the pancreas or when the body loses its ability to utilise insulin effectively or both. This leads to an accumulation of glucose in the blood of diabetic people which is detrimental for their health in the long term. Due to an increase in prevalence, the disease is becoming a growing concern to health authorities worldwide, especially in developing regions where inadequate health care systems and poor socio-economic conditions exacerbates the situation. A potential way of preventing diabetes is to limit starch digestibility to control blood glucose levels. Sorghum and maize are important food cereals in many regions of the world and they contain various phenolic compounds, particularly flavonoids which can inhibit starch hydrolysing enzymes like α-amylase. Therefore these cereals could have potential anti-diabetic properties. In this study, various extracts prepared from bran samples of white maize and white and red non-tannin sorghums were analysed for inhibitory activity against porcine pancreatic α-amylase using the Megazyme Ceralpha α-amylase assay kit. It was necessary to provide a basis for an understanding of the amylase enzyme inhibitory properties of the brans in relation to their phenolic content and therefore, their potential anti-diabetic properties. The total phenolic content of white maize and red and white non-tannin sorghum bran methanolic extracts was therefore determined, using the Folin Ciocalteu assay. The profile and concentration of flavonoids in extracts from the bran samples was determined using high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Red non-tannin sorghum bran and its extracts had higher inhibitory activity against porcine pancreatic α-amylase than bran and bran extracts from white maize and white non-tannin sorghum. Unextracted bran samples also inhibited the enzyme, indicating that the bran components inhibiting the enzyme did not need extraction and could exert inhibitory effects in situ. The bran of the red non-tannin sorghum varieties had significantly (p<0.05) higher levels of total phenolics (3.35 – 4.13 g CE/100 g) than that of the white maize (1.07-1.20 g CE/ 100 g) and white non-tannin sorghum varieties (0.99-1.15 g CE/ 100 g) as shown by results from the Folin Ciocalteu assay . Results from HPLC analysis showed that extracts from red sorghum varieties had significantly (p<0.05) higher levels of total flavonoids (166.8-269.8 mg/100 g) than extracts from white maize (18.7-24.8 mg/ 100 g) and white non-tannin sorghum (64.9-69.9 mg/100 g). Acidified organic bran extracts had higher total phenolics than non-acidified organic and water extracts. Results from LC-MS analysis showed that the acidified methanol extract from red non-tannin sorghum bran had the highest concentration of flavonoids with flavones (apigenin and luteolin) and flavanones (eriodictyol and naringenin) detected as the two main groups of flavonoids. In agreement with total phenolic and flavonoid content, this extract also had the highest α-amylase inhibitory activity. The water extract of the red non-tannin sorghum (Mr BUSTER), was the only water extract of all the grains that contained flavanones like eriodictyol, and was also the only water extract that showed inhibition against α-amylase. These observations indicate that the flavone and flavanone compounds identified in the extracts are important for inhibition of the α-amylase enzyme. Nutraceutical-type preparations from red non-tannin sorghum bran could have applications in foods as anti-diabetic agents by inhibiting α-amylase activity and thus controlling postprandial glucose levels in people suffering from diabetes. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Food Science / MSc / Unrestricted

Alternaria alternata (Fr.) Keissler is now widely recognized as the causal agent of brown spot and black pit of potatoes. Brown spot is a foliar disease with potential to cause 30% yield loss and postharvest losses of up to 10%. Losses are mainly due to premature defoliation. In this study, morphological and epidemiological characteristics of A. alternata were studied in order to understand the extent to which different light regimes influence radial growth, sporulation and pathogenicity of this pathogen. The role of low temperatures on initial sporulation was also investigated. Exposure of isolates to low temperatures (4°C) in the dark increased number of spores produced by isolates under all light conditions. Light did not have any effect on pathogenicity and isolate genetic capability had no influence on radial growth of isolates. The combined isolate and light effect (gene-environment interaction), had significant influence on both radial growth and disease severity. The taxonomy of the genus Alternaria has been highly debateable over the years, especially in small spored Alternaria species where identification is based entirely on morphological characteristics. This is mainly due to presence of closely related taxa such as Ulocladium, Macrosporium and Stemphylium that complicate correct identification of this genus. An investigation was carried out to determine the phylogenetic relationship as well to determine the relationship between molecular characterization and morphological identification. All isolates were identified as A. alternata based on morphology. The identity was further confirmed by molecular phylogeny using the GAPDH, EF1α and a combined phylogeny of these gene regions. All isolates formed one section with A. alternata. The isolates also grouped together with A. arborescens, A. tenuissima, A. longipes and A. gaisen, which were all recently characterized into the Alternata section. Comparison of RFLP digests of the ITS1 and ITS4 region revealed no genetic variability. The GAPDH and EF gene regions can therefore be used to delineate among Alternaria isolates and was in congruence with morphological identification. PCR-RFLP can be a useful tool in detecting genetic variability among isolates. Control of brown spot has mainly been through the use of strobilurins; however, recent disease epidemics on potatoes in South Africa led to an investigation into the failure of strobilurins to control brown spot. Samples were collected during the 2012-2013 growing season and eight Alternaria isolates were recovered from five growing regions. In vitro sensitivity tests showed that six of the eight isolates had reduced sensitivity to azoxystrobin. Sequence analysis of the cytochrome b gene revealed a mutation that led to an amino acid substitution which consequently led to reduced sensitivity. This study will lead to a better understanding of this new disease of potatoes that has proven to be of economic importance. Correct identification is paramount in disease management and this study has shown some reliable molecular technics that can be used to identify species in this genus correctly. This study was also able to link failure to control brown spot to fungicide resistance, and alternative control strategies can now be recommended to control this pathogen. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Microbiology and Plant Pathology / MSc / Unrestricted

Rwanda is developing country whose economy has been characterized by rapid urbanization in the last decade. The Government has embarked on projects like the Kigali master plan to boost development. In order to get around the hurdle of ownership and the right to property, states may compulsorily acquire property from an individual in the interest of the public. The rules that govern such acquisition of property must strictly followed otherwise the acquisition will be deemed illegal. Rwanda is party of UDHR by virtue of membership to the United Nations as well as several other international and regional treaties on human rights. The issue which forms the core of this research is the problem of displacement of inhabitants from a particular area earmarked for development. The issue of displacement arises in the compulsory acquisition of land. This imposes an obligation on policymakers to respect human rights when pursuing the objective of development and urbanization. This research exposes the challenges that have been associated with Rwanda’s law and policy on expropriation and proposes some recommendations. / Dissertation (LLM)--University of Pretoria, 2014. / lk2014 / Public Law / LLM / Unrestricted

In Suid-Afrika word daar minimumvonnisse vir, onder meer, verkragting voorgeskryf in artikel 51 van Wet 105 van 1997. Die doel van hierdie vonnisse is om ernstige en geweldadige misdaad te verminder, om kontinuïteit in vonnisse te bevorder en om die publiek tevrede te stel dat vonnisse ernstig en voldoende is. Lewenslange gevangenisstraf word as minimum straf in bepaalde gevalle van verkragting voorgeskryf in Deel I van Bylae 2 van Wet 105 van 1997. Afwyking van hierdie voorgeskrewe minimumvonnisse kan slegs geskied wanneer wesenlike en dwingende omstandighede dit regverdig. Die term ‘wesenlike en dwingende omstandighede’ word egter nie in die wetgewing omskryf nie en word die interpretasie daarvan, ongelukkig, aan die howe oorgelaat om moontlik sodoende regterlike diskresie te behou. Intra-familiële verkragting is ‘n sosiale probleem wat ‘n groot persentasie van Suid-Afrika se verkragting syfers uitmaak. In die meeste intra-familiële verkragting gevalle sal die voorgeskrewe minimumvonnis, lewenslange gevangenisstraf wees aangesien regspraak toon dat die meeste slagoffers minder as 16 jaar oud is. Regspraak oor die afgelope aantal jare toon egter wisselvallige uitsprake rakende die oplegging van die voorgeskrewe minimumvonnisse vir intra-familiële verkragting. ‘n Groot rede vir hierdie wisselvallige uitsprake is die verskillende interpretasie van wesenlike en dwingende omstandighede. ‘n Balans moet gehandhaaf word tussen die konsekwente toepassing van voorgeskrewe vonnisse en die behoud van regterlike diskresie. Bepaalde vonnisriglyne word vir hierdie doel voorgestel wat voortspruit uit ‘n behoorlike regsvergelykende studie oor die vonnispraktyke van Engeland en Wallis asook Nieu-Seeland. / Dissertation (LLM)--University of Pretoria, 2014. / lk2014 / Procedural Law / LLM / Unrestricted

The refining and transportation of crude oil often results in an inevitable accumulation of recalcitrant waste products such as oily sludge. Remediation processes such as landfarming and anaerobic landfilling have been recently ruled as inappropriate disposal methods, due to the length of time it takes for remediation to reach completion, as well as the uncontrollable release of harmful organics into the soil, atmosphere and potentially groundwater. This study focused on a biological treatment method for oily sludge using a plug flow reactor system. Biosurfactant-producing bacteria, Bacillus cereus, Klebsiella oxytoca and Cronobacter dublinensis were isolated from petroleum-contaminated and uncontaminated soil samples. Optimal growth of the bacteria was observed when incubated at ±30°C and biosurfactant activity was confirmed using the drop-collapse test. Oily sludge was simulated in the laboratory using fumed silica as intermediate compound to form Pickering emulsions. The recovery of oil involved the comparison of a plug flow system and a batch system. The plug flow system achieved up to 85% oil recovery from oily sludge while the batch system only achieved a maximum of 30% elution of the aqueous phase. The effect of waterflooding, in conjunction with biosurfactant-producing bacteria on the batch system had negligible effect while on the plug flow system, an increase of ±10% in percentage recovery was observed. GC-MS analysis of oil before and after the recovery process showed a reduction of concentration of certain compounds, suggesting possible degradation by bacteria or loss due to volatilization. TOC analysis showed a reduction in TOC of residual sludge, after completion of recovery process, suggesting degradation activity by bacteria trapped in the sludge matrix after the completion of the recovery process. Fifteen days after completion of recovery process, residual sludge from the plug flow system had a low TOC value of 1.03mg/L while sludge from the batch system had a much higher value of 7.119mg/L. The high percentage recovery of oil, coupled with the reduction of sludge TOC to negligible values suggest that MEOR is a feasible method for treatment of oily sludge and can be further investigated as a waste treatment procedure in the petroleum industry. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Chemical Engineering / MSc / Unrestricted