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Development of graphene materials and phthalocyanines for application in dye-sensitized solar cells

  • Authors: Chindeka, Francis
  • Date: 2020
  • Subjects: Dye-sensitized solar cells , Graphene , Phthalocyanines , Molecular orbitals , Impedance spectroscopy
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/166092 , vital:41328
  • Description: Two sets of dye-sensitized solar cells (DSSCs) were fabricated. In the first set, dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparative purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value obtained is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency. In the second set, DSSCs were fabricated by using 2(3,5-biscarboxyphenoxy), 9(10), 16(17), 23(24)-tri(tertbutyl) phthalocyaninato Cu (4) and Zn (5) complexes as dyes on the ITO-TiO2 photoanodes containing reduced graphene oxide nanosheets (rGONS) or nitrogen-doped rGONS (NrGONS). The evaluation of the assembled DSSCs revealed that using ITO-TiO2-NrGONS-CuPc (4) photoanode had the highest fill factor (FF) and power conversion efficiency (ɳ) of 69 % and 4.36 % respectively. These results show that the asymmetrical phthalocyanine complexes (4) and (5) showed significant improvement on the performance of the DSSC compared to previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
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  • Date Issued: 2020

Development of manganese phthalocyanine decorated with silver nanoparticles nanocomposite for improved electrocatalytic oxidation of hydrazine:

  • Authors: Mpeta, Lekhetho S , Sen, Pinar , Nyokong, Tebello
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/148472 , vital:38742 , https://doi.org/10.1016/j.jelechem.2020.114173
  • Description: In this study we report on the synthesis of tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl) phenoxy phthalocyaninato] manganese (III) chloride (MnPc). The MnPc was first used to modify a glassy carbon electrode, followed by the growth of silver nanoparticles (AgNPs) onto the MnPc modified electrode to form MnPc-AgNPs modified electrode. The modified electrode was characterized using cydic voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy. The modified MnPc-AgNPs electrode was employed for the detection of hydrazine. The MnPc-AgNPs gave better current responses for electrooxidation of hydrazine relative to MnPc and AgNPs, individually. The catalytic rate constant was 1.90 x 10(5 )M(-1) S-1, with the detection limit (LoD) of 2.42 pM (using 3 sigma notation), and sensitivity of 61.56 mu A mM(-1), for MnPc-AgNPs. (C) 2020 Elsevier B.V. All rights reserved.
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  • Date Issued: 2020

Development of MOVPE-grown InAsSb for barrier diode applications

  • Authors: Dobson, Stephen R
  • Date: 2020
  • Subjects: Gallium arsenide semiconductors , Electronics
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/49071 , vital:41598
  • Description: In this study, layers of GaSb, InAs and InAsSb are grown by metalorganic vapour phase epitaxy and characterised. Growth is conducted using the precursors of trimethylgallium, trimethylindium, trimethylantimony and tertiarybutylarsine. Focus is then placed on the characterisation of the materials, carried out by the techniques of X-ray diffraction, photoluminescence spectroscopy, Hall measurements and photocurrent spectroscopy. It is observed that V/III ratio plays a vital role in the growth of the GaSb and InAsSb layers. Epilayers of GaSb showed best crystalline quality when a V/III ratio of 1.2 was used at a growth temperature of 600 °C and a cell pressure of 600 Torr. Resultant Hall measurements indicated p-type GaSb. The Hall carrier concentrations of the p-type GaSb samples were analyzed considering electrical neutrality conditions and found to be highly compensated with evidence of band impurity conduction at low measurement temperatures. Both the donor and acceptor concentrations were determined to be of the order of 1016 cm−3 for all samples. For low temperature (< 150 K) a monovalent acceptor concentration is calculated to have an activation energy at approximately 20 meV. At high temperature (> 150 K) a divalent acceptor is extracted with an activation energy varying between samples based on compensation in a range of 90 meV to 70 meV. Photoluminescence measurements show four peaks with recombination mechanisms linked to the native acceptor identified in literature as either the gallium antisite and/or vacant gallium site. A fifth peak observed is attributed to the longitudinal phonon of the native acceptor. InAs and InAsSb epilayer are all grown at a temperature of 600 °C and cell pressure of 600 Torr. InAs is grown at a V/III ratio of 9.5 on GaAs substrate. Photoluminescence of the InAs layer shows two distinct peaks, one of which is an extrinsic band to band recombination. The other is attributed to free electron to acceptor or a donor-acceptor pair transition. An additional weak peak is also observed which is assigned to the longitudinal phonon of the band to band. InAsSb growth was conducted under a range of V/III ratios of 4.8 to 5, with a vapour phase composition of 0.4 to 0.435. Structural analysis via X-ray diffraction showed a 6 % to 12 % solid antimony content. Photoluminescence exhibited a single broad peak for all samples, with extended band tails. Temperature and power dependant analysis of luminescence indicated a convolution of extrinsic band to tail and band to band recombinations. Hall measurements indicated the InAsSb was n-type material with an apparent measured maximum mobility at 120 K of 9.5 × 103 cm2/V.s. and a room temperature apparent mobility of 7.5 × 103 cm2/V.s. Analysis of hall results using a two-layer model calculated a true bulk mobility of the epilayer at room temperature with an increased value of 15.4 × 103 cm2/V.s. The two-layer model details the effects of the surface conduction. From photoconductivity measurements and further analysis a resultant effective lifetime, at room temperature, was found to be on same order of magnitude as that of InAs materials. Application of a single Einstein oscillator extrapolated 0 K energy gaps for two samples of solid Sb contents of 6 % and 12 %, of 354 meV and 332 meV, respectively. Finally consideration was given to the growth of aluminium containing compounds, particularly AlGaSb. Multiple phases were observed under scanning electron microscope showing growth of GaSb regions surrounded by amorphous solid aluminium and/or aluminium oxide phases. The failure of the aluminium to incorporate into the desired crystal structure is speculated to be due to impure precursor introducing oxygen into the films. Additionally, the effectiveness of the gallium precursor compared to the aluminium precursor in helping the removal of the methyl groups at the growth surface, could also promote a preference for GaSb growth.
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  • Date Issued: 2020

Development of paper-based aptasensors for detection of Plasmodium falciparum lactate dehydrogenase in malaria

  • Authors: Ogunmolasuyi, Adewoyin Martin
  • Date: 2020
  • Subjects: Uncatalogued
  • Language: English
  • Type: thesis , text , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/164601 , vital:41147 , doi:10.21504/10962/164601
  • Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020
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  • Date Issued: 2020

Development of phthalocyanine functionalised TiO 2 and ZnO nanofibers for photodegradation of methyl orange

  • Authors: Mapukata, Sivuyisiwe , Nyokong, Tebello
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/186323 , vital:44485 , xlink:href="https://doi.org/10.1039/D0NJ03326J"
  • Description: The photocatalytic activity of TiO2 and ZnO based catalysts, which is based on their ability to generate electron–hole pairs upon photoillumination is limited due to their wide band gaps and lack of efficient retrievability post-application. This work reports on the fabrication, characterisation and comparison of electrospun TiO2 and ZnO nanofibers when bare vs when functionalised with a phthalocyanine. The generated photocatalysts are attractive because they absorb visible light and are easily retrievable and hence reusable. With the Pc anchored onto their surfaces, the anatase TiO2 nanofibers and the wurzite ZnO nanofibers possessed singlet oxygen quantum yields of 0.22 and 0.16 in water, respectively. Evaluation of the photocatalytic efficiencies of the nanofibers was conducted by studying the photodegradation of methyl orange. The Pc decorated nanofibers were found to be more effective photocatalysts than the bare ones with the phthalocyanine TiO2 nanofibers being the best. The degradation kinetics were found to follow pseudo first order kinetics and obeyed the Langmuir Hinshelwood model. The nanocatalysts reported herein are therefore feasible candidates for real-life water purification applications.
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  • 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.
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  • Date Issued: 2020

Dictionary culture in African language communities: research, development, challenges and prospects

  • Authors: Nkomo, Dion
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/467990 , vital:76997 , https://doi.org/10.1515/lex-2020-0002
  • Description: This paper reflects on aspects of dictionary culture in African language communities. It demonstrates how weak lexicographic traditions in African languages and present pedagogical practices in the public schooling system of African countries militate against the establishment of a thriving dictionary culture. This is against the gains made from the 1990s when the production of mother-tongue dictionaries gained traction in African languages and some efforts to provide for the integration of dictionary pedagogy in schools. The unavailability of dictionaries and the exclusion of dictionary pedagogy are identified as major challenges. The paper thus reiterates the need for the empowerment of teachers through formal training and also for the collaboration between lexicographers and other stakeholders as long-term solutions to the identified challenges.
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  • Date Issued: 2020

Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages

  • Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
  • Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
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  • Date Issued: 2020

Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages

  • Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/454320 , vital:75335 , xlink:href="https://doi.org/10.1016/j.fooweb.2020.e00152"
  • Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
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  • Date Issued: 2020

Differences in swimming stroke mechanics and kinematics derived from tri-axial accelerometers during a 200-IM event in South African national swimmers

  • Authors: Musson, Courtney Ruth
  • Date: 2020
  • Subjects: Swimming
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/46337 , vital:39588
  • Description: Context: Swimming is a highly competitive sport, with elite swimmers and coaches constantly looking for ways to improve and challenge themselves to meet new performance goals. The implementation of technology in swimming has proven to be a vital tool in athlete monitoring and in providing coaches with additional information on the swimmer’s performance. Example of this technology is the use of inertial sensory devices such as tri-axial accelerometers. The accelerometers can be used to provide kinematic information with regards to the swimmer’s stroke rate, stroke length and stroke mechanics. In a typical training session, coaches would have to manually time and count their swimmer’s strokes to be able to gain the kinematic information they require. Hence, the use ofinertial sensory technology, such as accelerometers, would provide the necessary information coaches require, allowing them to concentrate on other performance aspects such as theirswimmer’s technique.Aim and objectives: The aim of this study was to determine the kinematic parameters and swimming stroke mechanics that could be derived from tri-axial accelerometers, during a 200-m individual medley (IM) event in South African national level swimmers. Three objectives were set to meet the aim of the study. The first was to identify and differentiate each of the stroking styles using tri-axial accelerometers. The second was to identify and differentiate the kinematic parametersand stroke mechanicsfor all four strokes using tri-axial accelerometers. The third objective was to implement machine learning to automate the identification and interpretation of the accelerometer data. Method:A quantitative, non-experimental descriptive one group post-test only design was used, in which 15 national level swimmers, of which seven male and eight female (mean ±SD: age: 20.9 ± 2.90 years; height: 173.28 ± 10.61 cm; weight: 67.81 ± 8.09 kg; arm span: 178.21 ± 12.15 cm) were tested. Three anthropometric measures were taken (height, weight and arm span) prior to testing, with two tri-axial accelerometers and Polar V800watch and heart rate belt attached to the swimmers left wrist, upper-back and chest, respectively. All swimmerswere required to perform three main swimming sets: 50-m IM, 100-m variation and 200-mIM. Variousdescriptivestatisticsincluding mean, standard deviation and confidence intervals (95%)were used to describe the data. with further inferential statistics including paired t-test, intra-class correlation and Bland Altman analysis wereused to describe the relationship ivbetween the accelerometer and the manually estimated parameters. Additionally, arepeated measures one-way ANOVA (with post-hoc Tukey HSD test) werealso used in an inter-comparison of the stroke parameters between each of the stroking styles. A confusion matrix wasused to measure the classification accuracy of the machine learning model implemented on the accelerometer data.Results:The accelerometers proved successful in identifyingand discerningthe stroke mechanics for each of the four stroking styles, with the use of video footage to validatethe findings. In the stroke kinematic differentiation, theBland Altman analysisresultsshowed an agreement between themanual method and accelerometer-derived estimates, although a discrepancy was evident for several of the kinematic parameters, with a significant difference found with the estimated lap time, average swimming velocity and stroke rate (paired t-test: p <0.001 for all swim sets). The inter-comparison between the stroke parameters per stroking style showed a significant difference with average swimming velocity (repeated one-way ANOVA: F = 1789.37, p <0.001), averages stroke rate (repeated one-way ANOVA: F = 671.70, p <0.001) and average stroke length (repeated one-way ANOVA: F = 346.46, p<0.001) for the population group tested. Furtheranalysis with post-hoc Tukey HSD test showed no significant difference wereevident for the average swimming velocity(Tukey: p > 0.05for all strokes)andbetween freestyle and backstroke for the average stroke rate and stroke length (Tukey:p = 0.0968 andp = 0.997, respectively).Lastly, the machine learning model found a classification accuracy of 96.6% in identifyingand labelling the stroking styles fromthe accelerometer data.Conclusion: It was shown that the tri-axial accelerometers were successful in the identification and differentiation of all the stroking styles, stroke mechanics and kinematics, although a discrepancy was found with the average swimming velocity, stroke rate and lap time estimations. The machine learning model implemented proved the benefits of using artificial intelligence to ease the data process and interpretation by automatically labelling the accelerometer data. Therefore, the use of tri-axial accelerometers as a coaching aid has major potential in the swimming community. However, further research is required to eliminate the time-consuming data processingand to increasetheaccuracy of the accelerometer in the measurement of all the stroke kinematics.
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  • Date Issued: 2020

Digital media marketing and the consumption of sugar-sweetened beverages in Africa: A reception analysis of the multi-channel marketing of Coca-Cola among young Africans from the University of Lagos, Nigeria and Rhodes University, South Africa

  • Authors: Akingbade, Olutobi Elijah
  • Date: 2020
  • Subjects: Carbonated beverages -- Health aspects -- South Africa , Carbonated beverages -- Marketing -- South Africa , Soft drinks -- Health aspects -- South Africa , Soft drinks -- Marketing -- South Africa , Carbonated beverages -- Health aspects -- Nigeria , Carbonated beverages -- Marketing -- Nigeria , Digital media -- Marketing -- Africa , Soft drinks -- Health aspects -- Nigeria , Soft drinks -- Marketing -- Nigeria , Digital media -- Marketing -- Nigeria , Obesity -- Africa , Nutritionally induced diseases -- Africa , Coca-Cola Company -- Marketing , Rhodes University -- Students -- Attitudes , University of Lagos -- Students -- Attitudes
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/163125 , vital:41012
  • Description: This study investigates and examines how Coca-Cola’s marketing communications, especially the newer forms of digital, social and mobile media marketing messages/campaigns, are received, understood and made sense of by two sets of purposefully selected young urban African students in Nigeria and South Africa. Embedded within a qualitative research design and underpinned by an interpretative phenomenological analysis (IPA) approach, this study was conducted against the backdrop of the recent surge in the consumption of Sugar Sweetened Beverages (SSBs) which has been directly implicated in the rise of obesity and a variety of non-communicable diseases (NCDs) in Africa. The thesis explores the role of multinational SSBs in this surge, as African countries have become key focus areas for multinational food and beverage companies seeking growth and profits, as home markets decline partly due to better health communications and, in some cases, the implementation of so-called ‘sugar taxes’ and the attendant negative publicity around these taxes. The focus on young Africans from Nigeria and South Africa was motivated by the similar rapid urbanisations in both countries, often accompanied by changes in diet and greater consumption of fast foods and SSBS, and by South Africa’s ranking as the country with the highest prevalence of overweight persons and obesity in Sub-Saharan Africa. Similar rises in national average weights are now also starting to be seen in Nigeria, as are surges of diet-related disease incidence and prevalence. The study is informed by Consumer Culture Theory (CCT) but also draws on other theories and some key concepts from marketing studies, health science and psychology. Methodologically, the study draws on in-person observations, focus group interviews and semi-structured individual in-depth interviews, to explore how Coca-Cola has created a deep and evocative historical ‘brandscape’ and how it has become a multicultural resource in both South Africa and Nigeria. Through an investigation into the lived experiences of study participants with regards to both their earliest and more recent engagements with Coca-Cola, as a brand and as a product, the study delineates the influence of older generations of Coke enthusiasts and consumers within participants’ households and newer spaces of interaction with Coke via interactive, highly personalised social media-centric campaigns. This study explores how the ubiquitous nature of Coca-Cola’s aesthetics and signage are engaged with – often in very ‘sub-conscious’ ways – by these students and how more recent social media campaigns evoke this multigenerational history. Unpacking study participants’ self-understandings of Coke and their often ‘sub-conscious’ engagements with the SSB, this study explicates the underpinning ideological grounding and how this is sustained over time to become an hegemonic code that does not only confine participants’ engagements with SSBs to Coke but also confines their reception of, and engagements with, Coke’s media marketing messages/campaigns to those that resonate with the multigenerational history evoked by the SSB. It is within this contextual background that this study brings to the fore participants ‘cognitive dissonance’ and scepticism and often rank disbelief of the health risks posed by their high levels of Coke consumption. The study concludes that attempts to raise awareness about the dangers inherent in excessive consumption of SSBs in Africa need to be reviewed and rethought. There is a need for long-term, consistent and much more proactive health journalism, alongside public health campaigns in both official and indigenous languages, to dispel the powerful myths created by SSB marketing and explain how SSBs are implicated in the rise of diet-related NCDs in Nigeria and South Africa.
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  • Date Issued: 2020

Digitization as a strategy for preservation of and access to private collections in the Eastern Cape: a case study of National Heritage and Cultural Studies Centre and International Library of African Music

  • Authors: Tyali, Lungisani
  • Date: 2020
  • Subjects: Preservation Digitization
  • Language: English
  • Type: Thesis , Masters , MSoc. Sci (Library and Information Science)
  • Identifier: http://hdl.handle.net/10353/18302 , vital:42250
  • Description: The aim of the study was to investigate digitization as a strategy for the preservation and access to private collections in Eastern Cape covering National Heritage and Cultural Studies Centre (NAHECS) at the University of Fort Hare, Alice campus and International Library of African Music (ILAM) at Grahamstown. The objectives of the study were: to find out the types of artefacts digitized at NAHECS and ILAM; to describe the available infrastructure for the digitization of collections at NAHECS and ILAM; to determine the impact of digitization on the preservation of and access to digitized materials; to find out the extent to which digitization programme at NAHECS and ILAM comply with the relevant legal and regulated framework, and to investigate challenges to the current digitization programmes at NAHECS and ILAM. The study used a purposive non-probability sampling technique to select the participants. Data was collected using self-administered questionnaires and face-to-face interviews. Qualitative data collected was analysed using thematic analysis while quantitative data were analysed statistically using SPSS software using frequencies, pie charts, bar charts and percentages. The findings of the study revealed that there are different challenges faced by both institutions (that is, ILAM and NAHECS). Some of the challenges faced by ILAM include inadequate funds for supporting the digitalizing project/ programme, inadequate staff and poor infrastructure. The finding has shown that the majority of respondents’ indicated that NAHECS has available knowledge of infrastructures such as Meta Data and Audio for the digitization of collections while all respondents confirmed that ILAM has the various distribution of available instrument for digitization and these include Meta Data, Video Tapes and Audio. iv The study recommends that proper necessary access to the digitized documents should be made available through Africa Media Online (AMO) so that all the interested users can search for digitized materials.
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  • Date Issued: 2020

Dimensions and indicators of non-profit financial condition: evidence from South African public universities

  • Authors: Bunting, Mark B
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/150296 , vital:38965 , DOI: https://doi.org/10.4102/sajems.v23i1.2974
  • Description: More than three decades of research have failed to achieve convergence on a method for the measurement of non-profit financial condition, with the literature reporting a bewildering array of financial dimensions, and more than 100 ratios and indicators. This article offers a contribution to a broader discourse in non-profit financial analysis by recognising, and taking action in response to, the potential threat to research validity arising from the generally unchallenged presumption that accounting numbers provide a complete, unbiased and error-free representation of an entity’s underlying economic reality.
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  • Date Issued: 2020

Direct nonlinear optical absorption measurements of asymmetrical zinc (II) phthalocyanine when covalently linked to semiconductor quantum dots

  • Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/186056 , vital:44459 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128729"
  • Description: We report on nonlinear optical properties of tris[(4-tert-butyl)-2-thio (phenyl)acetic acid (1) and tris(dimethyl-5-(3,4-phenoxy) isophthalate (2) phthalocyaninato zinc (II) complexes. The synthesized complexes were covalently conjugated to glutathione-capped CdTe/ZnSe/ZnO quantum dots. We observed an increase in triplet quantum yield with corresponding decrease in fluorescence quantum yield of conjugates compared to Pc complexes alone. Z-scan technique was employed to experimentally test the nonlinear optical response of complexes and nanoconjugates in solution at laser excitation wavelength of 532 nm with 7 ns pulse. Nonlinear absorption coefficient, third-order optical susceptibility and optical limiting threshold of the materials were obtained from the Z-scan data. The nonlinear absorption parameters improved in the presence of CdTe/ZnSe/ZnO, with 1 and 1-CdTe/ZnSe/ZnO, giving the best results due to the presence of electron donating substituents.
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  • Date Issued: 2020

Disco

Discursive constructions of alcohol use and pregnancy among participants in intervention aimed at reducing Foetal Alcohol Spectrum Disorders

  • Authors: Msomi, Nqobile Nomonde
  • Date: 2020
  • Subjects: Fetal alcohol spectrum disorders -- South Africa , Pregnancy -- Psychological aspects , Reproductive rights -- South Africa , Reproductive health -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/140374 , vital:37883
  • Description: South Africa’s socio-cultural and political history has had significant effects on maternal and reproductive health. The hazardous alcohol use patterns in the country have affected alcohol consumption during pregnancy. Antenatal exposure to alcohol may result in Foetal Alcohol Spectrum Disorders (FASD). The levels of FASD in particular areas of the country are the highest recorded in the world. Epidemiological studies have dominated pregnancy and FASD research in South Africa; however, recently critical scholarship seeking to contextualise the issue of drinking alcohol during pregnancy is emerging. This study forms part of a developmental/formative assessment of an alcohol and pregnancy intervention. Assessment is an important part of pilot interventions, and discourse is a key area of focus due to its constitutive role for the subjectivity of human beings and legitimation of institutional practices. Using a reproductive justice perspective and a Foucauldian approach to analysis, I identified five prominent discursive constructions of alcohol use during pregnancy produced during interviews with community educators. These interviews were conducted following training workshops with the community educators. Participants constructed their living environments as ‘wholly bad’ and ‘issue-ridden’ and positioned alcohol consumption as ‘a destroyer!’, ‘king’ and a social lubricant. They interpellated the foetus, the ‘FASD child’ and pregnant women into this context. They positioned themselves as transformed subjects able to effect change. The foetus was constructed as ‘vulnerable and important’, as opposed to the ‘defiled FASD child’. Pregnant women were constructed as ‘ignorant, preoccupied and unreceptive to knowledge’. These constructions hinged on so-called ‘scientific knowledge’ of biological processes in utero, demonstrating Foucault’s conception of the power/knowledge nexus and how its dynamics transforms knowledge of human beings. Whereas this ‘knowledge’ transformed alcohol consumption and the foetus into powerful and vulnerable subjects respectively, the circulating discourses had objectivising effects on pregnant women. The discourses of responsibilisation, the personification of the foetus, ‘the problem’ category of FASD, the discourse of difference, and the discourse of alcohol consumption as an entrenched practice were circulating around pregnant women. I suggest alterations to the identified constructions using principles of community psychology, the harm reduction model, a social model of disability and the reproductive justice perspective
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  • Date Issued: 2020

Dismissal for racist remarks and racism

  • Authors: Du Plessis, Armand
  • Date: 2020
  • Subjects: Employees -- Dismissal of -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: http://hdl.handle.net/10948/47359 , vital:39850
  • Description: Racism has always been a hard and tough battle fought by all South Africans. Since the independence of the Republic of South Africa has racism in the workplace become a very popular tendency. Ever since has there been a number of legislation which has been incorporated to specifically address this behaviour, but remains the question whether this legislation has achieved what its drafters aimed to have achieved. There will also be a comparison to the implemented legislations of Australia and England aimed at addressing and prohibiting racism in the workplace. Throughout this study, attention will be brought to specific words which have been used in the past by particular employees towards their fellow employees and the consequences thereof. Recently, the Supreme Court of Appeal and our Constitutional Court had to relook at the definition of “hate speech” in terms of certain legislation within South African and came to the conclusion that this definition must be amended to include, and also exclude, particular words and phrases in order for the existing definition thereof to be more precise and clear. The main aim of this study is to determine whether the dismissal of an employee, based on racism in the workplace, or for the utter of racism remarks in the workplace, can warrant the dismissal of that specific employee, and should dismissal not be the appropriate sanction, to determine what sanction would be appropriate in such circumstances. The writer hereof, has aspired to achieve his goal throughout this study that racism in the workplace should not be tolerated, and that employees who make themselves guilty thereof, should be punished in a serious manner.
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  • Date Issued: 2020

Disputes about the interpretation, application and breach of collective agreements

  • Authors: Roelofse, Cornelius Johannes
  • Date: 2020
  • Subjects: Collective labor agreements -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: http://hdl.handle.net/10948/47414 , vital:39988
  • Description: Section 24 of the Labour Relations Act 66 of 1995 (the Act) regulates disputes about the interpretation and application of collective agreements. On the face of it, there is nothing particularly complicated about section 24 of the Act. This section provides that, if there is a dispute about the interpretation or application of a collective agreement, any party to the dispute may refer the dispute to the CCMA; firstly, if the agreement itself does not provide for its resolution by conciliation or arbitration by another body; secondly, if the dispute resolution procedure is inoperative and finally, if a party is frustrating the resolution of the dispute under the dispute resolution provisions of the collective agreement. Most bargaining council main agreements provide for the resolution of disputes concerning the interpretation or application of their collective agreements by conciliation or, if that fails, by arbitration. But what exactly is the scope of these provisions, and what are the powers of arbitrators when entertaining such matters? These questions are significant. If the scope of section 24 of the Act is as limitless as it seems, and if arbitrators acting in terms of that section have full powers not only to interpret and apply the provisions of collective agreements, but also to order parties not only to comply with them, and to make restitution to the other party if they haven’t, then statutory arbitrators may make orders equivalent to those that courts may make in actions for breaches of contract and, potentially, arbitrate matters over which they would not otherwise have jurisdiction. This could complicate affairs if the collective agreement being interpreted and applied is incorporated into the employment contracts of the employees concerned. The Act does not expressly set out the powers of arbitrators dealing with disputes under section 24 of the Act. For a long time after the promulgation of the Act, statutory arbitrators were generally of the view that section 24 meant what it apparently says, that it empowers arbitrators both to declare the true meaning of collective agreements to apply and to enforce them, also to order defaulting employers to compensate employees for the financial loss they have suffered in consequence of the breach. However, this understanding of what section 24 of the Act entails was thrown into confusion by two judgments of the Labour Appeal Court (LAC), Johannesburg City Parks v Mphahlani NO1 (Johannesburg City Parks) and Minister of Safety and Security v SSSBC (SSSBC). 2 In this treatise a discussion and analysis will follow of how these two judgments influenced future case law about the meaning and scope of section 24 of the Act and the uncertainties it created.
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  • Date Issued: 2020

Distribution, habitat associations and conservation of the Eastern Cape rocky Sandelia bainsii (Perciform: Anabantidae) in the Great Fish River system

  • Authors: Sifundza, Delsy Sindy
  • Date: 2020
  • Subjects: Anabantidae -- South Africa -- Great Fish River , Perciformes -- South Africa -- Great Fish River , Labyrinth fishes -- South Africa -- Great Fish River , Fishes -- Effect of human beings on -- South Africa -- Great Fish River , Fish populations -- South Africa -- Great Fish River , Fish declines -- South Africa -- Great Fish River , Fish populations -- Monitoring -- South Africa -- Great Fish River , Anabantidae -- Evolution -- South Africa -- Great Fish River , Gene flow , Mitochondrial DNA , Microsatellites (Genetics) , Eastern Cape rocky Sandelia bainsii , Freshwater ecology -- South Africa -- Great Fish River
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/142692 , vital:38102
  • Description: In South Africa, freshwater ecosystems are under pressure due to increasing anthropogenic factors degrading river systems. The Cape Fold, the lower Southern Temperate Highveld and the Amatolo – Winterberg Highlands freshwater ecoregions contain some of the heavily impacted river systems in the country. One such river system is the Great Fish River system, which has been affected by anthropogenic modification (hydrological modification, water pollution and invasion by non-native fish species). These modifications have raised conservation concerns on an imperilled anabantid fish, the Eastern Cape rocky Sandelia bainsii that is confined to the Kat and Koonap rivers, which are tributaries of the Great Fish River. Historically, the species was reportedly common and abundant, with a range spanning across seven river systems (Kowie, Great Fish, Keiskamma, Igoda, Gxulu, Buffalo and Nahoon rivers) in the Eastern Cape Province. However, surveys have indicated that the species has experienced decline in population size and distribution range, with localised extirpations being reported. This resulted in its listing on the IUCN Red List of threatened species as Endangered. The proposed shale gas exploration and potential infrastructure development in the Karoo basin, which encompasses the headwaters of the Kat River, represent a potential future threat to the remnant populations of this species. The aim of the present study was to review the past and present distribution range of S. bainsii, determine the habitat associations and assess the conservation of S. bainsii in the Great Fish River system. This information is essential for informing conservation and management decisions for this species in the Great Fish River system. This study undertook a comprehensive survey of the Kat and the Koonap rivers in 2017, and augmented this information with data from more recent surveys that were conducted from 2009 - 2014 to map the distributions freshwater fishes in the Great Fish River system. Data from these recent surveys (2009 – 2017) were compared with historical records (1961 – 2005) obtained from the South African Institute for Aquatic Biodiversity to evaluate changes in distribution patterns of S. bainsii. Historical records indicated that S. bainsii occurred at 11 localities in the Kat River and three localities in the Koonap River. Data from recent surveys indicated that the species has persisted at these historical localities, except one locality in the Koonap River where no individuals of S. bainsii were captured, despite the use of multiple sampling approaches and gears. Although the species still persists at two of the three historical localities in the Koonap River, the population sizes have considerably declined as the species was reportedly in high abundance at these localities in the 1980s. Factors threatening the continued existence of this species in the Koonap River likely include non-native species, extreme drought conditions and the associated excessive abstraction of water which has resulted in the drying of some of the refugia pools where the species was historically common and abundant. In contrast to the Koonap River, the 2017 survey indicated that in the Kat River, S. bainsii had a similar distribution range compared to historical records. The species occurred at 11 of the 41 localities that were sampled in the Kat River, and the sampled populations consisted of all size classes. Sandelia bainsii occurred with other native fish species in the system, including Labeo umbratus, Enteromius anoplus and Glossogobius callidus. A comparison of historical and recent data indicates that non-native fishes have likely not expanded their ranges in the Kat River. This is likely due to the presence of weirs and dams that have prevented upstream movement of non-native fish species L. aeneus, C. gariepinus and T. sparrmanii which are now abundant in the lower Kat and mainstem Great Fish River. Surveys from the present study indicated that although S. bainsii still persists within the Kat River, there are a number of factors that pose a considerable threat to the continued existence of this species in the Great Fish River system. Chapter 3 evaluated the habitat associations of S. bainsii based on 10 physical and chemical variables and distribution data collected from 30 localities in the Upper Kat River and seven of its tributaries. A non-metric multidimensional scaling model was used to assess the distribution patterns of S. bainsii in relation to environmental variables. Furthermore, a negative binomial generalised linear model (GLM) was used to assess the relationship between the abundance of S. bainsii and environmental variables. Results from the present study indicated that S. bainsii was a habitat generalist as the distribution of this species showed no specific association with any of the habitat variables that were considered in this study. The species occurred in a wide range of habitats, including rocky sections in the upper Kat River and its tributaries as well as the mainstem sections. The GLM however indicated that the abundance of S. bainsii was negatively associated with increasing conductivity. In addition, the Kat River contains multiple weirs of variable sizes. Future studies should therefore evaluate the effects of these weirs on population fragmentation, gene flow and long-term evolutionary potential of S. bainsii through the application of techniques such as mitochondrial DNA and microsatellites.
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  • Date Issued: 2020

Diteng tsa ditlhopha tsa maina a Bantu: ntlhathakanelo e le mo Setswanang : “The semantics of Bandu noun classes: a focus on Setswana

  • Authors: Tladi, Oboitshepo
  • Date: 2020
  • Subjects: Tswana language , Tswana language -- Grammar , Tswana language -- Noun , Noun , Bantu languages , Bantu languages -- Noun , Bantu languages -- Grammar
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/167654 , vital:41500
  • Description: The present study investigated the semantic classification of the Setswana noun class system. This enquiry falls under the broad area of the noun classification system in Bantu languages, psycholinguistics and lexicogrpahy. Specifically it explores the basis of noun classification in Setswana making indications that Setswana noun classification is based on a partial semantic classification. Data for the study was drawn from the Setswana Oxford Dictionary. Sixty Setswana nouns, from class 1, 3, 5, and 7, were selected and analysed and then grouped into semantic categories (i.e., PERSON, DEROGATION, TRANSPORATION and so forth). The study adopted Kgukutli’s (1994) semantic classification in performing the dictionary analysis. The rest of the data was drawn from the intuitions of thirty-nine contemporary speakers of Setswana, with the aid of a linguistic test which was fashioned according to Selvik’s (2001) psycholinguistic test. The language test required participants to match the predetermined Setswana definitions with hypothetical Setswana nouns with selected class prefixes attached to them. The results from the empirical study showed that speakers were associating prefixes to certain semantic values, suggesting that each noun class had specific semantic content that was unique to that class. The semantic categories created through the dictionary analysis were then compared to those given by the thirty-nine Setswana speakers, to analyse whether there were any similaritires in the semantic classification of the noun classes. The findings of the dictionary analysis and linguistic test revealed that there were certain semantic characteristics that each class was associated with that seemed to be unique to the class. However, there were various semantic overlaps in the semantic categories associated with the different noun classes, which brings into question whether a semantic classification is viable in the classing of nouns. The study suggests that prior classification of Setswana nouns are not precise enough and that additional semantic categories are needed to offer a more precise classification of nouns in this language.
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  • Date Issued: 2020
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