The diet and feeding ecology of the brown house snake, Boaedon capensis

Masters of ScienceAfrican brown house snakes (Boaedon capensis) are widely thought to be dietary specialists that predominantly consume rodents. Given their ubiquitous distribution, these snakes potentially play an important role in controlling rodent populations throughout their range. However, the full extent of the diet of this species remains poorly quantified, and the proportional importance of mammals to their diet is speculative. Moreover, little is known regarding intraspecific dietary variation of these snakes. In recent years, a dearth of reports of B. capensis feeding, particularly from novel information-sharing streams available through social media, suggests that the diet of these snakes may be broader than previously thought. B. capensis are not rodent specialists as amphibians (3%), birds (12%), and reptiles (38%) collectively comprise a significant proportion of their diet. There was no evidence for sexual size dimorphism or dietary variation between adult males and females. However, significant differences in morphology and prey utilisation between adults and juveniles indicate an ontogenetic shift in diet from small lizards to larger, and more diverse prey. Variation in climate and time of year did not affect diet. Importantly, the diet of B. capensis as presented by museum data vastly differed compared to literature and community science reports. In particular, the proportional use of reptiles differed across sources (museum data = 6%; community science data = 27%). Overall, my findings reiterate the importance of examining multiple sources of information when characterizing the diet of species, as these multiple sources provide different result outcomes

Probing large-scale structure with the SKAO and other cosmological surveys

Philosophiae Doctor - PhDIn recent history there have been several advances in cosmology, which has significantly shaped our understanding of the Universe. The current leading theory is called ΛCDM, which can successfully model the expansion of the Universe from a primordial state and describe the dynamics of its contents, thereby resulting in the large-scale structure present today. The model is based on general relativity, that describes gravitational interaction as the curvature of a four-dimensional manifold called space-time. However, despite the many successes of ΛCDM, there are a number of things that need further investigation. The Cosmic Microwave Background (CMB) is the oldest observable radiation in the Universe, and this cosmological relic contains a detectable structure. The process leading up to the CMB determines the initial conditions of ΛCDM, but is still poorly understood. It is widely accepted that inflation was responsible for the rapid expansion after the Big Bang, although this is yet to be verified experimentally. The distribution of the primordial potential is imprinted on ultra-large scales of the matter distribution, which offers an important insight into uncovering this mystery. In addition to the primordial Universe, there are other concepts that still puzzle us in ΛCDM itself. The fact that we have been unable to directly detect and explain these dark components (that make up around 96% of the Universe) has prompted several theorists to consider alternative cosmological models. Therefore, testing general relativity and ΛCDM is still an essential part of cosmological research. A key observational discriminant between general relativity and modified theories of gravity is the rate at which the large-scale structure grows from small perturbations. The relativistic effects (or light-cone effects) expected in general relativity also offer an independent test of the gravitational model

Polydopamine coated platinum catalysts to improve fuel cells durability

>Magister Scientiae - MScPolymer electrolyte membrane fuel cells (PEMFC) are in the forefront of energy production and have drawn a great deal of attention in both fundamental and application in recent years. It is a promising energy system used in commercialized electric vehicles presenting with the following advantages: low-temperature operation, high power density (40%–60%), nearly zero pollutants compared to conventional internal combustion gasoline vehicles, simple structure, and so on. There are, however, two major obstacles which obstruct PMFCs pathway to commercialization— durability and cost. Recent advances in PEMFC systems showed the most common fuel cell catalysts to be Platinum (Pt) (or platinum alloys) supported by high surface carbon in both the cathode and anode. However, carbon is very susceptible to corrosion and results in lower durability of Pt supported catalysts

Social media, protest and citizen participation in local government: A comparison between the City of Cape Town and Johannesburg metropolitan municipalities: 2010 to 2017

Philosophiae Doctor - PhDThis study’s central focus is to assess how various classes of people in in distinct localities across Cape Town and Johannesburg use social media in citizen participation concerning municipal governance processes. While largely drawing on interviews, the study also uses quantitative descriptive data. While some scholars believe that social media use will contribute to civic decline, others think that it has a role to play in re-invigorating civic life. This study has found that there is a gap in understanding important differences in the ways various classes in different contexts mobilise and adapt social media and that the capacity of the “poor” and their social movements to engage as collective citizens using social media has been understated. The wealthy social movements rely more on litigation and money power. Each social group adapts social media to suit its socio-political imperatives and context. South Africa’s major municipalities still lean towards traditional spaces of citizen participation and bureaucratic insulation

Development of a training programme for professional nurses to promote the use of postpartum family planning in Epe local government area, Lagos state, Nigeria

Philosophiae Doctor - PhDPostpartum family planning (PPFP) is the initiation of family planning methods among postpartum women, within 12 months after delivery. During this period, the women are a vulnerable group of people with high unmet need for family planning. They are exposed to the risks of unwanted pregnancy, which potentially, could increase maternal mortality, due to the consequences of too frequent pregnancies. Studies have revealed a consistent low use of family planning during the postpartum period. Additionally, it has been documented that the low use of postpartum family planning, most likely, was attributed to inadequate services that had been rendered at healthcare centres, as well as poor motivation by those providing family planning services

The paracrine effect of normoxic and hypoxic cancer secretions on blood-brain barrier endothelial cells

>Magister Scientiae - MScCancer is the most common leading cause of death worldwide. Glioblastoma and breast cancer are the most aggressive solid tumour. The survival rate of these tumours depends on their ability to progress and spread. These cancers use their high proliferative capabilities for survival, increasing their malignancies. Glioblastoma is considered the most aggressive tumour initiated in the brain, whereas breast cancer is the most common metastatic cancer in the brain, both types of cancer are known as high infiltrated cancer and their invasiveness due to their capability to release factors that can alter the neighbouring cells to facilitate their progression

Hydrothermal conversion of agricultural and food waste

>Magister Scientiae - MScThe global dependence on non-renewable fossil fuels to meet energy needs cannot be sustained for a long time and it is already evident in the escalation of fuel prices over the past decade. This research was performed towards renewable energy production from agricultural and food waste. The use of agricultural and food waste has benefits such as being grown in a land that is not in competition with food crops protein, all year round availability, and having high lipid content. The produced bio-crude oil can be upgraded to remove moisture and acidity level, and can be used as a substitute for heavy oils such as diesel to power static appliances or can be used as petrol distillate fuel alternative. Hydrothermal liquefaction (HTL) process is one of the commonly used technologies for converting agricultural and food waste into liquid biofuels

Investigating novel aspects of the blood-brain barrier using high resolution electron microscopy

Doctor ScientiaeThe blood-brain barrier (BBB) is a restrictive interface located between the blood circulation and the central nervous system (CNS), regulating the homeostatic environment of the neuronal milieu, by controlling the permeability of the cerebrovasculature. Currently, we cannot fully comprehend the regulatory features and the complexity of BBB morphology to allow for intervention clinically. The thesis consists of four publications. The methodology paper proposes a novel experimental design to visualize the morphological architecture of immortalized mouse brain endothelial cell lines (bEnd3/bEnd5). The brain endothelial cells (BECs) were grown on cellulose matrices and fixed in 2.5 % glutaraldehyde in preparation for visualization of the paracellular (PC) spaces between adjacent BECs, employing high-resolution electron microscopy (HREM), with vested interest in the morphological profile of the developing BEC. The second publication addresses and reports on the nanosized detail of BEC monolayer morphology utilizing high-resolution scanning electron microscopy (HR-SEM) and published the first descriptions of the extrusion of a basement membrane from developing in vitro BECs. Moreover, we categorized and discussed two types of nanotubule (NT) development specific for the establishment of the BEC monolayers. NTs can occur via nanovesicle extrusion onto the BEC membrane surfaces, which fuse, forming tunneling NTs (TUNTs) between adjacent BECs. Furthermore, cytoplasmic extensions of BEC membrane leading edges give rise to tethering NT (TENTs), which result in overlapping regions across the PC spaces, resulting in PC occlusion. BEC NT communication is illuminated in a third publication utilizing immunofluorescence microscopy, which reports on the molecular, cytoskeletal elements governing NT formation. This study shows, for the first time, f-actin and α-tubulin cytoskeletal proteins extending between the soma of the cells and NT cytoskeletal structures within an in vitro BBB model. Thereafter, the effects depolymerizing agents, Cytochalasin D and Nocodazole, were investigated on f-actin and α-tubulin cytoskeletal protein generation,functionality of NT morphology, cell division and permeability. For the first time, we show that f-actin possesses an additional function, key to tight junction, plaque protein organization. Moreover, it facilitates TENT formation, essential for cytoplasmic projection across PC spaces. Conversely, α-tubulin facilitates known functions: (i) transportation, (ii) cytokinesis, (iii) cellular division, and (iv) possesses a novel function as the molecular cytoskeletal backbone of TENTs, which facilitates BBB impermeability. A critical review evaluates past literature, in light of the current findings emanating from this study. The review critiques the concept of BEC cilia, which have been reported in the literature, comprised of tubulin and actin, but at low-resolution. In the light of our novel observations, nowhere in transmission electron microscopy do we observe cilia on the BECs, we postulate that NTs have been misnamed and mischaracterized as cilia. The thesis endeavors to elucidate the complexity of BEC nanostructures by examining the emerging role of the nanoscopic landscape of BBB development and the changing nature of BEC morphology, NT formation and associated cytoarchitectural underpinnings governing NT morphology. The research study attempts to, with a view to create new avenues for treating brain pathology, revolutionize our interpretation of barrier-genesis on a nanoscale

Microwave synthesized ruthenium antimony oxide-graphene nanocomposite materials for asymmetric supercapacitors

Philosophiae Doctor - PhDWith the rapid rise in energy demand and ever-escalating environmental hazards, the need for transition from fossil fuel to renewable energy sources is of paramount importance, requiring better and efficient energy storage devices such as supercapacitors. Supercapacitors are energy storage devices with high power density and long cycle life, but relatively low energy density when compared to batteries. New and advanced electrode materials are required to improve the energy density requirements of next-generation supercapacitors. However, the search for new types of active materials to be used as supercapacitors' electrodes continues to be a tough challenge. Herein, ruthenium antimony oxide (RuSbO) and ruthenium antimony oxide graphene (RuSbO-G) were synthesized via the microwave-assisted method for the first time and tested as a possible electrode material for an asymmetric supercapacitor. Graphene oxide prepared by modified Hummer’s method was exfoliated at low temperature and used for the synthesis of RuSbO-G.202

Determining crop coefficients for irrigated fruit tree crops using readily available data sources

>Magister Scientiae - MScThe climate variability and climate change-induced events experienced worldwide have caused a significant decrease in the rainfall volume. South Africa is considered to be one of the driest countries in the world, as it receives an average annual rainfall that is lower than the global annual average. To sustain and grow the agricultural sector, South Africa supplements the low rainfall with its freshwater resources, for irrigation purposes. This action is necessary, especially for meeting the high water requirements of the South African fruit industry, as it is one of the major exporters of fruit in the world. Research has been conducted in an attempt to accurately quantify the water requirements of various fruits, which will assist farmers to save water, to increase their productivity and to managing their irrigation water. However, a knowledge of the water use, actual water consumption rates and the factors that drive them, is minimal and inadequate, and this has had a detrimental effect on the effective management of irrigation water and water allocation by the responsible stakeholders