Showing items 101 - 120 of 1219

Your selections:

Cytotoxicity of triterpenoids from Clerodendrum glabrum against triple negative breast cancer cells in vitro:

  • Authors: Teclegeorgish, Zecarias W , Mokgalaka, Ntebogeng S , Vukea, Nyeleti , de la Mare, Jo-Anne , Tembu, Vuyelwa J
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/161511 , vital:40634 , https://doi.org/10.1016/j.sajb.2020.07.009
  • Description: Clerodendrum glabrum is an indigenous medicinal plant that is used to treat cough, cold, sore throat and chest complaints. The stem bark of Clerodendrum glabrum afforded four tritepenoids namely, 3β-olean-12-en-3-yl palmitate (β-amyrin palmitate), (1), 3β hydroxy 5-glutinene (glutinol), (2), 3β-lup-20(29)-en-3-palmitate (Lupeol-3-palmitate), (3), 3β-lup-20(29)-en-3-ol (lupeol) (4) and one common phytosterol (stigmasterol) (5). The structures were established on the basis of their spectroscopic analysis. The compounds were screened for cytotoxicity against the HCC70 triple negative breast cancer (TNBC), MCF-7 hormone receptor positive breast cancer and MCF-12A non-cancerous mammary epithelial cell lines.
  • Full Text:
  • Date Issued: 2020

Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts

  • Authors: Taylor, Richard Peter
  • Date: 2020
  • Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/153746 , vital:39507
  • Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
  • Full Text:
  • Date Issued: 2020

Biomes, geology and past climate drive speciation of laminate-toothed rats on South African mountains (Murinae: Otomys)

  • Authors: Taylor, Peter J , Kearney, Theresa , Dalton, Desire L , Chakona, Gamuchirai , Kelly, Christopher M , Barker, Nigel P
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/425481 , vital:72249 , xlink:href="https://doi.org/10.1093/zoolinnean/zlz134"
  • Description: Mitochondrial DNA sequences (1137 bp) of the cytochrome b gene and craniodental and craniometric data were used to investigate the evolutionary relationships of six putative rodent taxa of Otomys (family Muridae: subfamily Murinae: tribe Otomyini) co-occurring in the Western Cape and Eastern Cape provinces of South Africa. Phylogenetic analysis of 20 new sequences together with craniodental and craniometric characters of 94 adult skulls reveal the existence of a unique lineage of Otomys cf. karoensis (named herein Otomys willani sp. nov.) from the Sneeuberg Centre of Floristic Endemism in the southern Drakensberg Mountain Range. Craniometric analysis distinguished O. karoensis from O. willani and identified a further four localities in the range of the latter species. We document southern range extensions of both Sloggett’s ice rat, Otomys sloggetti, and the vlei rat Otomys auratus to the Sneeuberg Mountain Range, in addition to appreciable genetic divergence between Sneeuberg and southern and central Drakensberg populations of O. sloggetti. Our results demonstrate parallel patterns of cryptic speciation in two co-occurring species complexes (Otomys irroratus s.l. and O. karoensis s.l.) associated closely with the boundaries of biomes (fynbos vs. grassland biomes) and geological formations (Cape Fold Belt vs. Great Escarpment).
  • Full Text:
  • Date Issued: 2020

Habitat requirements affect genetic variation in three species of mayfly (Ephemeroptera, Baetidae) from South Africa:

  • Authors: Taylor, Chantal L , Barker, Nigel P , Barber-James, Helen M , Villet, Martin H , Pereira-da-Conceicoa, Lyndall L
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/149314 , vital:38824 , https://doi.org/10.3897/zookeys.936.38587
  • Description: This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread (Afroptilum sudafricanum) and two stenotopic and thus endemic (Demoreptus natalensis and Demoreptus capensis) species, all of which co-occur in the southern Great Escarpment, South Africa. Mitochondrial DNA was analysed to compare the genetic diversity between the habitat generalist and the two habitat specialists. Afroptilum sudafricanum showed no indication of population genetic structure due to geographic location, while both Demoreptus species revealed clear genetic differentiation between geographic localities and catchments, evident from phylogenetic analyses and high FST values from AMOVA.
  • Full Text:
  • Date Issued: 2020

Gamma-Ray and X-Ray Observations of the Periodic-repeater FRB 180916 during Active Phases:

Non-standard employment in terms of the labour relations act

  • Authors: Tatchell, Veronique
  • Date: 2020
  • Subjects: Labor laws and legislation -- South Africa , South Africa -- Labour Relations Act, 1995 , Flexible work arrangements -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: http://hdl.handle.net/10948/49027 , vital:41594
  • Description: Historically, employers utilised non-standard or atypical forms of employment in order to avoid statutory obligations in respect of these employees, and in turn justify differential treatment of said employees.1 As a result, non-standard employees were not on the same footing as their permanent counterparts. They were not remunerated on the same level, were not privy to advancement and training opportunities, and did not enjoy a sense of job security due to the ease at which their employment could be terminated, rendering them a vulnerable class of workers.2 There was pandemonium in the employment sphere of society due to the abusive practices faced by employees employed in terms of Temporary Employment Services, this was accompanied by a call to ban labour broking. The legislature, while acknowledging the important role that this form of employment plays in the labour market and broader economy, opted for increased regulation of this and other types of non-standard employment; instead of an outright ban. As a result thereof, the Labour Relations Act3 was amended by the Labour Relations Amendment Act,4 with a view of improving the regulation and protection of employees engaged in these forms of non-standard or atypical employment. This study seeks to determine whether the amendments have achieved the purpose of enhancing the job security of these employees.
  • Full Text:
  • Date Issued: 2020

High genetic diversity and limited spatial structure in an endangered, endemic South African sparid, the red steenbras Petrus rupestris:

  • Authors: Tang, Wei , Qiu, Yuanyuan , Li, Xiaonan , Soy, Rodah C , Mack, John , Nyokong, Tebello
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/160390 , vital:40441 , DOI: 10.6060/mhc200183l
  • Description: Earth-abundant first row transition metal corrole complexes have played an important role in fundamental research due to their unique molecular structures and attractive properties. In comparison to porphyrins, corroles have three inner N-H protons and are ring-contracted with a smaller macrocyclic cavity. First row transition metal corroles have been widely used as effective electrochemical catalysts for small molecule activations, such as hydrogen evolution, oxygen reduction/evolution and CO2 reduction reactions (HERs, ORRs/OERs and CO2 RRs) through homogenous and/or heterogenous prodecures. Several strategies have been used to modulate the catalytic efficiency of synthetic metallocorroles.
  • Full Text:
  • Date Issued: 2020

The Influence of Clientelism on the Informal Sector in Zimbabwe : a Case Study of Glen View 8 Complex, Harare

  • Authors: Tandire, Justin
  • Date: 2021-04
  • Subjects: Patron and client -- Zimbabwe -- Harare , Informal sector (Economics) -- Zimbabwe -- Harare , Informal sector (Economics) -- Political aspects -- Zimbabwe -- Harare , Patronage, Political -- Zimbabwe -- Harare , ZANU-PF (Organization : Zimbabwe) , Zimbabwe -- Social conditions , Glen View Complex 8 (Zimbabwe)
  • Language: English
  • Type: thesis , text , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/177986 , vital:42896 , 10.21504/10962/177986
  • Description: This study focuses on the influence of clientelism in the informal sector of Zimbabwe in Glen View 8 (Complex). The study used the case of Glen view 8 (complex) in Harare Province. The study focused on political dynamics in the informal sector; livelihood strategies employed by informal sector operators; manifestation of “Big Men”, social networks in the informal sector; and different strategies employed by operators to overcome the problems of political manipulation, clientelism and patronage. It employs a qualitative research methodology to enable a nuanced comprehension of the clientelistic relationships that take place in the informal sector of Zimbabwe. Through in-depth interviews, focus group discussions, narratives and in-depth interviews with key informants, the study explored the clientelistic nature of the informal sector. The major findings of the study are that the informal sector in Zimbabwe is influenced by political patronage. It was established that patronage influences the informal sector in Zimbabwe in general and at Glen View Complex 8 in particular. Some of the operators revealed that patronage negatively affects their business as they are sometimes forced to attend political party meetings either at the complex or at ZANU-PF star rallies in town. The operators experience a plethora of problems such as lack of security, poor sanitation, stiff competition, poor infrastructure, lack of insurance and fire outbreaks. It has been revealed that most of the problems experienced at the complex are a result of the politicisation of the informal sector particularly by the ZANU-PF party. Operators at the complex have described the politicisation of the informal sector as a major drawback to their efforts of realising maximum benefits from their work. Therefore, the thrust of this thesis is premised on the de-politicisation of the informal sector as the starting point in the transformation of the activities of the operators. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
  • Full Text:
  • Date Issued: 2021-04

Dataset and ANN model prediction of performance of graphene nanolubricant with R600a in domestic refrigerator system

  • Authors: Taiwo, Babarinde , Stephen, Akinlabi , Daniel Makundwaneyi, Madyira , Ekundayo, Funmilayo M , Paul Adeola, Adedeji
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/3139 , vital:43150 , (https://www.sciencedirect.com/science/article/pii/S2352340920309926)
  • Description: This work evaluated the steady state performance of R600a in the base lubricant and graphene nanolubricant. The measuring instruments required and their uncertainties were provided, step by step method and procedures for preparation of graphene nanolubricant concentration and substituting it with the base lubricant in domestic refrigerator system are described. The system temperatures data was captured at the inlet and outlet of the system components. Also, the pressures data was recorded at the compressor inlet and outlet. The data was recorded for 3 h at 30 min interval at an ambient temperature of 27 °C. The experimental dataset, Artificial Neural Network (ANN) training and testing dataset are provided. The artificial intelligence approach of ANN model to predict the performance of graphene nanolubricant in domestic refrigerator is explained. Also, the ANN model prediction statistical performance metrics such as Root Mean Square Error (RMSE) and Mean Absolute Deviation (MAD), Mean Absolute Percentage Error (MAPE) and coefficient of determination (R2) are also provided. The data is useful to researchers in the field of refrigeration and energy efficiency materials, for replacing nanolubricant with the base lubricant in refrigerator systems. The data can be reuse for simulation and modelling vapour compression energy system.
  • Full Text:
  • Date Issued: 2020

Ethics and education as practices of freedom

  • Authors: Tabensky, Pedro
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/305672 , vital:58602 , xlink:href="https://doi.org/10.1080/00131857.2020.1791822"
  • Description: On the one hand, according to Richard Rorty, Paulo Freire and others, education is the practice of freedom. On the other hand, according to Michael Foucault, Mary Midgley and others, ethics is the practice of freedom. How, then, are education and ethics related to one another and what do these authors mean by ‘the practice of freedom’? In this piece, I argue that education and ethics are two mutually constitutive aspects of the practice of freedom. Individuals who are able to engage in this practice can most properly be said to be the authors of their lives, that is, individuals who, to borrow from Neil MacGregor, are able to find their ‘place in things’. To find our ‘place in things’ is to do the necessary educative work required for becoming the authors of our lives, that is, for self-actualization (as Rorty and John Dewey have argued). To take on the authorial role is, moreover, to be able effectively to take control of our lives, to organize them into unities for which we are individually responsible. This, according to Midgley, is precisely what it is to be ethical. This work, moreover, requires ongoing development, that is, education, in Dewey’s sense. I further argue that professional education and skills training cannot be understood properly in isolation from these broader educational aims and I criticize mainstream educational practices for not paying sufficient attention to the intimate relationship between the vocational and non-vocational aspects of education.
  • Full Text:
  • Date Issued: 2020

Detection of the in vitro modulation of Plasmodium falciparum Arf1 by Sec7 and ArfGAP domains using a colorimetric plate-based assay:

  • Authors: Swart, Tarryn , Khan, Farrah D , Ntlantsana, Apelele , Laming, Dustin , Veale, Clinton G L , Przyborski, Jude M , Edkins, Adrienne L , Hoppe, Heinrich C
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/165418 , vital:41242 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-020-61101-3
  • Description: The regulation of human Arf1 GTPase activity by ArfGEFs that stimulate GDP/GTP exchange and ArfGAPs that mediate GTP hydrolysis has attracted attention for the discovery of Arf1 inhibitors as potential anti-cancer agents. The malaria parasite Plasmodium falciparum encodes a Sec7 domain-containing protein - presumably an ArfGEF - and two putative ArfGAPs, as well as an Arf1 homologue (PfArf1) that is essential for blood-stage parasite viability. However, ArfGEF and ArfGAP-mediated activation/deactivation of PfArf1 has not been demonstrated.
  • Full Text:
  • Date Issued: 2020

Development of Tio 2 nanostructure arrays for photonic extraction of hydrogen gas

  • Authors: Suliali, Nyasha Joseph
  • Date: 2020
  • Subjects: Nanostructures , Nanostructured materials Hydrogen
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/49314 , vital:41620
  • Description: Amid the energy crisis of the 21st century, renewable energy is a thriving field of study, light harvesting materials being a central theme due to the abundance of solar energy. Nanostructured TiO2 is the most studied photocatalysis material, since the discovery of its energy harvesting properties by Fujishima and Honda in 1972. Environmentally friendly products such as hydrogen fuel, can be produced using TiO2 due to its non-toxicity, chemical stability and photocatalytic activity. The surprising aspect of this important material is that it can be prepared using cost-effective methods such as hydrothermal synthesis, solution gelation and anodic oxidation. This research focused on the three key elements required to develop TiO2 photoelectrodes i.e. the deposition of Ti films on transparent substrates, a thorough analysis of the chemistry of the anodic oxidation process and the development of the TiO2 thin films. Glass substrates that have Ti films are the base component for TiO2 photoelectrode production. Ti films with thicknesses up to 4 μm, were developed on commercial F-doped SnO2 (FTO) glass substrates using high-power impulse magnetron sputtering (HiPIMS). The sputter deposition experiments were performed in the 1 to 8 kW range at a substrate temperature of 500 °C and Ar pressure of 400 mPa. At higher powers, thicker films were deposited, resulting in increased intensity of Xray-diffraction peaks. However, on comparing the XRD patterns, the (001) peak outgrew the rest regardless of thickness of the film. The deposition process therefore favoured orientation of most of the α-Ti phase crystallites with the [001] axis perpendicular to the substrate surface. Surface roughness results were interesting, showing a non-linear dependence of the surface roughness on HiPIMS pulse energy in the 1 to 8 kW range. The surface roughness is highest at the starting deposition power of 1450 W and reduces to a minimum at 4500 W. From this minimum, it increases to its second highest value at 7900 W. From this data, the parameters required to produce Ti films of lowest surface roughness, for deposition on commercial Technistro® FTO glass, were deduced at the inflection point, where the deposition power was 4500 W. The surface roughness obtained is a critical result for the anodic production of quality TiO2 photoelectrodes, which if high, leads to uneven etching, thus irregular and inefficient photoelectrodes. Direct current magnetron sputtering was also carried out in the 1 to 5 kW range to obtain ratios of power-normalised growth rates of the Ti films. This investigation provided the Ti films on FTO glass, the transparent, conductive substrates which were used to develop TiO2 photoelectrodes. To elucidate the chemistry of anodic oxidation of Ti, a mathematical model of the anodic current density, which had not been reported at the time of its publication, was developed. The technique, a highlight of this research, is a predictive numerical computation of the instantaneous quantities of species that participate in the anodization process. From eleven chemical reactions, 14 first order ordinary differential equations were compiled using the principles of chemical reaction kinetics. The pattern, transient behaviour and response to anodization parameters of the current density signal, were successfully predicted. Strong agreement between the model and measurements was demonstrated in seven experiments. The results confirm that the current density signal is a numerical integral of the kinetics of redox reactions of water. The bulk of this research was on the development of TiO2 nanotubular arrays on Ti foil substrates and Ti films on FTO glass. TiO2 films with well-defined tubular structures were synthesised. The films were developed in anhydrous, polar organic hosts with water and etching agents in the range of 10 V to 70 V. The control of geometrical properties of the tubes such as the length, pore diameter, wall thickness, tube separation and number of nanotubes per unit area was demonstrated. Anatase only and mixed anatase-rutile phase compositions were obtained at different annealing temperatures. Nanotubes with diameters as small as 20 nm and thickness as high as 29 μm were produced. Apart from an increase in nanotube thickness, a decrease in distance between nanotubes grown in diethylene glycol was observed at longer anodization times. Studies of the effects of anodization parameters on the current density measured, morphological and crystallographic properties of the nanotube films were conducted in three main investigations. The first was the study of the effect of anodization parameters on current density. Besides the obvious increase of current density with anodic voltage, the first steady state of the growth process was found to depend on the NH4F concentration. The second investigation focused on the effect of accelerated growth of TiO2 nanotubular films. In the study, 9 μm-thick nanotube films were synthesised at twice the growth rate of a 9 μm-thick control sample. The array obtained by accelerated growth had distinguishable nanotubes, however, the morphological quality was reduced. The third investigation demonstrates the control of the number of nanotubes per unit area. By varying the etchant content, the anodic voltage and the viscosity of the electrolyte host, various distributions were obtained. The research ends with a photoelectrochemical application: measurement on photocurrents generated in a two-electrode setup. The photocurrent densities measured in the off and on conditions were 30 nA/cm2 and 2.57 μA/cm2, respectively, demonstrating photoactivity of the developed films.
  • Full Text:
  • Date Issued: 2020

Oral Phytothymol ameliorates the stress induced IBS symptoms

  • Authors: Subramaniyam, Selvaraj , Yang, Shuyou , Diallo, Bakary N , Fanshu, Xu , Lei, Luo , Li, Chong , Tastan-Bishop, Özlem , Bhattacharyya, Sanjib
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/426034 , vital:72308 , xlink:href="https://doi.org/10.1038/s41598-020-70420-4"
  • Description: Physical stressors play a crucial role in the progression of irritable bowel syndrome (IBS). Here we report a heterogeneous physical stress induced IBS rat model which shows depression and subsequent modulation of IBS by oral treatment of thymol. Oral administration of Thymol reduces the stress induced IBS significantly altering the stress induced gastrointestinal hypermotility, prolonged the whole gut transit time, and increased abdominal withdrawal reflex suggesting gastrointestinal hypermotility and visceral discomfort caused the onset of depression. Immunohistochemical analysis in small intestine and colon of rats shows the decreased 5-HT3AR expression level while thymol treatment normalized the 5-HT3AR expression in the stressed rats. Molecular docking studies showed that thymol competes with endogenous serotonin and an antagonist, Tropisetron and all have similar binding energies to 5-HT3AR. Molecular dynamics simulations revealed that thymol and tropisetron might have similar effects on 5-HT3AR. Our study suggest that thymol improves IBS symptoms through 5-HT3AR, could be useful for the treatment of IBS.
  • Full Text:
  • Date Issued: 2020

Shrub and bird community response to fire in dune thicket of the southeastern Cape, South Africa

  • Authors: Strydom, Tiaan
  • Date: 2020
  • Subjects: Fire prevention -- Research -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/47635 , vital:40260
  • Description: Fire studies within the Cape Floristic Region (CFR) are restricted to the impacts of fire on plants and birds in fire-prone fynbos while little is known about post-fire responses of shrubs and birds in fire-avoiding subtropical dune thicket, which coexists with fynbos but burns on much longer cycles. Fire is deemed important for maintaining the boundaries between fynbos and thicket. It has been hypothesised that high-intensity fires prevent fire-dependent fynbos from being replaced by fireavoiding subtropical thicket (hereafter thicket) on dune landscapes of the CFR. I posit that (1) fire-related thicket shrub mortality would be size dependent, with smaller individuals suffering higher mortality than larger ones; and (2) that survival and resprouting vigour of thicket shrubs would be negatively correlated with fire intensity. In relation to the response of birds to fire I posit that (1) fire reduces bird species richness and bird abundance in thicket during the first two years post-fire; and (2) fire changes feeding guild composition and results in the loss of frugivorous birds. Extensive fires in dune thicket along the southeastern Cape coast presented the opportunity to assess the responses of thicket shrubs and birds to fire. For the thicket shrubs I assessed survival and resprouting vigour of thicket shrubs post-fire in relation to fire intensity and pre-fire shrub size at two dune landscapes (Cape St Francis and Knysna) in the CFR. I furthermore compared bird species richness, bird abundance and feeding guild composition between burnt and unburnt thicket (only at Knysna). A total of 29 species and 1112 individuals of thicket shrub were surveyed, with post-fire survival being high (83-85%). Smaller shrubs had a lower probability of post-fire survival than larger individuals but there was no consistent relationship between shrub mortality and fire intensity. Fire intensity had a positive effect on resprouting shoot count but a variable effect on resprouting volume. In the bird study a total of 66 bird species and 2404 individuals were recorded of which 52 species and 1176 individuals were in burnt thicket and 60 species and 1228 individuals were in unburnt thicket. Ten species occurred only in burnt thicket and 13 species only in unburnt thicket. Insectivores and generalists were the most common feeding guilds in terms of richness and abundance in both burnt and unburnt thicket. Frugivores were more abundant in unburnt thicket than burnt thicket, whereas granivores were more abundant in burnt thicket than unburnt thicket. I conclude that thicket shrubs and bird communities are resilient to fire. Prescribed high-intensity fires in dune landscapes are unlikely to reduce the extent of thicket in fynbos or radically change the bird communities. The effects of fire on thicket shrubs and birds are likely to be short-lived as thicket shrubs resprout vigorously after fire resulting in rapid recovery of vegetation and thus bird habitat structure. However, frequent fires may prevent the encroachment of thicket shrub juveniles into fynbos, owing to the greater vulnerability of small shrubs to fire. Most recruitment of thicket shrub individuals into fynbos is via ramets that likely originate from well-established plants in mature thicket stands. These mature unburnt thicket stands provide habitat for various forest bird species and can function as refuge areas for birds and other wildlife in fire-prone landscapes. However, there is no need for managers to take any precautions when implementing controlled burns or controlling wildfires because not all thicket patches in the landscape are likely to burn.
  • Full Text:
  • Date Issued: 2020

The role of northwest striking structures in controlling highgrade ore shoots at the Syama Gold Mine, Mali, West Africa

  • Authors: Soro, Ali
  • Date: 2020
  • Subjects: Syama Gold Mine , Gold ores -- Geology -- Mali , Veins (Geology) -- Mali
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/145209 , vital:38418
  • Description: This study intended to investigate the relationship between the NW striking structures and the high-grade ore shoots at the Syama gold mine in Mali, West Africa. All structural data collected since 1987 from drill core have been integrated to allow the interpretation and modelling of these NW-SE structures. The structures collected were grouped into three main groups; foliations/shears/faults, veins and joints/contacts/fractures. Micromine software was used to plot the structures, printed out on A3 paper and interpreted manually using tracing paper. Analysis and interpretation of stereographic plots has shown that the majority of the high-grade zones are generally located at the intersection of the NNE structures and the NW structures. The observed cross-cutting relationship between the NNE and the NW structures suggests two different generation of faults. It is suggested that the NW structures were active during the D4 deformation event (Standing, 2007) and have played a role in reactivating earlier (D3) NNE structures, allowing greater fluid flow and enhancing the gold grade. These zones are mainly defined by brecciation and stockwork veining. The E-W structures are believed to be the latest and are attributed to the D5 event. Although gold mineralisation is grossly controlled by the NNE structures, the NW structures need to be considered as major gold enrichment upgrading factors at Syama. It is therefore strongly recommended that ongoing exploration at Syama specifically target the intersection of the NW and NNE structures as favourable zones for high-grade mineralisation.
  • Full Text:
  • Date Issued: 2020

Phytoplankton of the Southern Agulhas Large Marine Ecosystem (sACLME)

  • Authors: Sonnekus, Martinus Jakobus
  • Date: 2020
  • Subjects: Botanical chemistry
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/47646 , vital:40261
  • Description: The southern Agulhas Large Marine Ecosystem (sACLME) consists of the greater Agulhas Current system, including the areas influenced by the Agulhas Current, the Agulhas Shelf, Agulhas Bank, Agulhas Retroflection as well as the Agulhas Return Current. Four biogeographical regions were identified within the sACLME and the composition of the phytoplankton communities and the associated physico-chemical variables in each were investigated. Water temperature and nitrate concentration were found to be the main drivers of the sACLME phytoplankton community. A total of 215 phytoplankton taxa were identified that were separated into two groups: the Agulhas Current group and the Southwest Indian Ocean Ridge group. The structure of the phytoplankton community was consistently homogeneous throughout the sACLME. Nutrient concentrations of the water varied, but nitrate was the most abundant source of nitrogen, especially in regions that were subjected to the upwelling of cold nutrient-rich water. The phytoplankton communities were significantly influenced by the availability and stoichiometry of the macronutrients nitrogen; phosphorus and silicon. The low mean N:P ratio of 5.5 is an indication that the waters of the sACLME are generally nitrogen limited, as is typical of oceanic systems. There is a change in phytoplankton cell size and functional groups within in the various water masses that are specific to certain biogeographical regions within the Agulhas Current system. It is clear that frontal systems may form barriers between phytoplankton communities.
  • Full Text:
  • Date Issued: 2020

A theory-based approach to evaluating a Continuing Teacher Professional Development Programme aimed at strengthening environment and sustainability education

  • Authors: Songqwaru, Nonyameko Zintle
  • Date: 2020
  • Subjects: Fundisa for Change , Environmental education -- South Africa , Teachers -- Training of -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/145267 , vital:38423
  • Description: This study uses a theory-based approach to evaluate the Fundisa for Change training programme, a continuing teacher professional development programme aimed at strengthening environment and sustainability education. The aim of the study was to surface assumptions that underpin the design and implementation of the Fundisa for Change training programme. The Fundisa for Change Teacher Education programme is a national collaborative programme that is implemented in all the nine provinces of South Africa. The study reports on the implementation of the programme in five provinces. The study aimed to surface the Fundisa for Change training programme’s implementation theory and programme theory as these affect programme delivery. The Fundisa for Change training programme was implemented in diverse contexts by different facilitators to different participants. To determine how training programme outcomes were achieved, use was made of context-mechanism-outcome (CMO) configurations for each site where the programme was implemented. Data used to construct CMO configurations was generated through document analysis of Fundisa for Change documents, interviews with stakeholders and participants, as well as observations of programme implementation at five sites. There were three phases to data analysis: content analysis of Fundisa for Change documents, content analysis of observation transcripts and use of the CMO configuration, an analytical tool used in realist evaluation. An initial CMO configuration was constructed prior to observing implementation of the programme and a refined CMO configuration for the Fundisa for Change training programme was constructed based on similarities between the CMO configurations constructed for each of the five sites under study. The partnership model of the Fundisa for Change training programme brought diverse expertise and resources (material, cognitive, social and emotional) which were conducive to the achievement of programme outcomes. The programme’s action context (structure, culture, agency and relations) contributed to the achievement of programme outcomes by participants. Participants’ subject content knowledge, teaching practice and assessment practice was enhanced through attending the Fundisa for Change training. On-course tasks were mediated during training and this created opportunities for participants to discuss and reflect on current practice in ways that could lead to a change in practice. In evaluating professional development programmes, an elaborated definition of context in terms of structure, culture, agency and relations enables a comprehensive exploration of potential programme mechanisms that can be activated when programmes are implemented. It is also important to disaggregate resources and reasons when identifying mechanisms as this assists with differentiating between context and mechanisms. The study offers insights into the professional learning of teachers grappling with new content and pedagogical content knowledges related to environment in the context of recent curriculum changes where the South African national school curriculum has come into focus. Environmental education programmes in South Africa have implicitly used a realist approach. This study offers the first substantive professional learning evaluation that develops this approach explicitly using Theory of Change and Realist Evaluation in combination.
  • Full Text:
  • Date Issued: 2020

Combining DNA barcoding and morphology to identify larval fishes from the nearshore environment off the south-east coast of South Africa

  • Authors: Somana, Zinzi Sinazo
  • Date: 2020
  • Subjects: Fishes -- Larvae -- South Africa -- Identification , Fishes -- Genetics -- Research -- Technique , Fishes -- South Africa -- Classification , Genetic markers
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/144605 , vital:38362
  • Description: The early life history stages of most marine fish species are undescribed. The problem is, most of these fishes have pelagic larvae which are minute, delicate forms. Linking the larval stage to an adult counterpart is extremely challenging as larvae are morphologically different from the adults. Historically, larval fish identification relied solely on distinguishing morphological characteristics and meristic measurements, which has resulted in taxonomic confusion and misidentification. The introduction of the deoxyribonucleic acid (DNA) barcoding technique as an alternative approach has been successful in positively identifying larval fishes. The correct identification of larval specimens is the key to a better understanding of larval ecology, which underpins the success of any adult fish population. This study aimed to positively identify larval fishes of the south-east coast of South Africa using morphological characteristics and DNA barcoding. Larval and eggs specimens for this study were collected from the shallow nearshore waters of the south-east coast of South Africa. A total of 177 larval specimens were used for morphological analysis. Body shape, gut shape, pigmentation and morphometric measurements (such as body depth, preanal length and total body length) were used to identify each specimen to the family level. In addition, a fragment of mitochondrial cytochrome c oxidase subunit 1 gene (COI) was adopted for sequencing to identify larval fish specimens and fish eggs. Sequences generated from this study were compared to those in the Barcode of Life Database (BOLD). When there were no close matches to a sequence, the GenBank nucleic acid sequence database, maintained by the National Center for Biotechnology Information (NCBI), was used as an alternative. A total of 18 different families were identified through morphology. Seventy-seven of the 177 larval specimens were not subjected to morphological identification due to physical damage. The majority of larvae identified using morphological characteristics belonged to either the Sparidae, Tripterygiidae or Gobiesocidae fish families. Through DNA barcoding, 12 fish families, 16 genera and 18 different species were identified. Ten DNA barcodes (categorised as ‘no match’) from 10 different larval specimens were not identified through any of the online databases. Therefore, the 2% threshold value was used to identify members of the same species. The K2P genetic distance relationships were calculated among the no match sequences and downloaded probability matches from NCBI. This resulted in two unknown specimens assigned to the Blenniidae and Gobiidae. All other taxa were identified to species level, except specimens representing the Gobiidae and Tripterygiidae families. Based on the K2P genetic distances Gobiidae representatives were categorised as members of the Caffrogobius genus. Twenty-eight barcodes represented specimens from the Tripterygiidae. DNA barcode data from COI was analysed using the standard phylogenetic procedures in MEGA6 to examine relationships and differentiation among sequences. These could not be identified to the lowest taxonomic rank due to limited sequence data to compare them with. The sequence data from these specimens gave different results in the two online databases. BOLD results were to family level (Tripterygiidae) and NCBI to the species level (Clinidae: Pavoclinus profundus). Results in this study confirmed the efficiency of the DNA barcoding technique in species level identification of fish larvae. The evidence from genetic barcodes of the Tripterygiidae specimens, supported by morphological characteristics, suggests the need for thorough research to identify the individuals to the species level. The fact that this study identified taxonomically problematic Gobiidae and Tripterygiidae specimens suggests that studies similar to this may highlight additional diversity and help to resolve the taxonomy of other species in these families. However, the lack of reference sequence data from the adult specimens, and especially those with cryptic diversity, were both shortcomings for the positive identification of larvae. With that being said, it shows the necessity for more research to be conducted on barcoding of larvae in general as to accommodate all kinds of species from biodiversity to economic perspectives.
  • Full Text:
  • Date Issued: 2020

Visualising the Psyche: Perspectives on mental health in the medium of comics

  • Authors: Solomon, Tayla Shan
  • Date: 2020
  • Subjects: Spiegelman, Art -- Maus , Kelly, Joe, 1971- -- I kill giants , Niimura, J M Ken -- I kill giants , Brosh, Allie -- Hyperbole and a half , Comic books, strips, etc. -- Psychological aspects , Comic books, stripa, etc. -- Therapeutic use
  • Language: English
  • Type: text , Thesis , Masters , MFA
  • Identifier: http://hdl.handle.net/10962/148413 , vital:38737
  • Description: The field of Psychology is constantly shifting in its understanding of mental health. Scholars have been critiquing Psychology’s narrow perspective of what constitutes ‘normal’. Many dealing with mental health issues fear that they will be misunderstood and are confronted with systems and institutions that they find unempathetic. This mini-thesis conceptualises creative empathy as a solution to these problems. It is based on the idea that every experience is unique and therefore cannot be wholly understood without engaging in an imaginative process. The appropriateness of the comics medium as a tool for promoting this strategy is explored with a focus on the use of visual imagery to tell stories of distressing experiences. It looks at Tayla Shan Solomon’s The Adventures of Apparently-Anyone-Can-Do-It-If-TheyJust-Try Bug! (2019), Art Spiegelman’s Maus (I & II) (1986), Joe Kelly and JM Ken Niimura’s I Kill Giants (2011), and Allie Brosh’s Hyperbole and a Half: unfortunate situations, flawed coping mechanisms, mayhem, and other things that happened (2013). This mini-thesis analyses various techniques employed by comics artists to create compelling stories of idiosyncratic experiences, including the use of symbolic imagery and framing.
  • Full Text:
  • Date Issued: 2020

Human capital Development and Economic Growth: A cross country study

  • Authors: Sokanti, Thembalethu
  • Date: 2020
  • Subjects: Economic development Human capital
  • Language: English
  • Type: Thesis , Masters , MCom (Economics)
  • Identifier: http://hdl.handle.net/10353/18985 , vital:43005
  • Description: The study examined the impact of human capital development on economic growth for 129 countries comprising of developed and developing countries. The primary focus of the study is on examining the contribution of human capital index components on economic growth for the period 2014 to 2017. The panel data model was employed in the study. Firstly, the hausman test was used to determine the suitable method between fixed and random effects. The fixed effects model was selected as the best panel econometric technique to be used in the study. The empirical results showed that there is a positive and statistically significant relationship between human capital index components (capacity, development, deployment and know how) and economic growth. The study also found that these components of human capital index have more impact on economic growth when they are interacted together based on theories of human capital and economic growth. Capacity and development are found to be the best contributors to economic growth for all the regions; thus, the study recommends that for economic growth to be increased, countries should invest more of their funds on capacity and development sub- indexes of human capital index. Exchange rates and inflation are found to have a negative relationship with the economic growth, while interest rates are found to have a positive and statistical relationship with the economic growth. The study also found out that there is a regional effect associated with human capital development, with European region being the best contributor to GDP. The components of human capital index also found to be important for all regions to invest on to improve economic performance. Deployment is found not to be significant is Sub-Saharan Africa. The existence of income group effect is found with developed countries performing much better compared to developing countries. The study also recommended that countries should invest more of their wealth in human capital development components such as education and health to enhance their economic growth
  • Full Text:
  • Date Issued: 2020
  • Disclaimer
  • Privacy
  • Copyright
  • Contact