Development and evaluation of the coach-athlete relationship enhancement intervention
- Authors: Kuit, Wim
- Date: 2018
- Subjects: Interpersonal relations , Coaching (Athletics) -- Psychological aspects Sports -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/22508 , vital:29989
- Description: An expanding body of sport psychology theory and research has highlighted the central role of the coach-athlete relationship (CAR) in the performance, satisfaction and well-being of coaches as well as athletes. Models have been developed that identify the key dimensions of CAR quality and the interpersonal behaviour that maintains it, but there remains a need for interventions that support coaches and athletes to optimise their interpersonal skills. This can be done by harnessing recent advances in personality theory which emphasise a more holistic and developmental view of the person and provide a basis for greater mutual understanding and adaptive interpersonal behaviour change in the CAR. The aims of this study were to develop the Coach-Athlete Relationship Enhancement (CARE) intervention through an integration of the Enneagram personality typology with current models of the CAR, and then to evaluate the impact of the CARE intervention on CAR quality. Sixty-two university-level athletes and their nine coaches participated in the study. Quantitative and qualitative results indicate that the CARE intervention significantly enhanced CAR quality, including direct and meta-perceptions of closeness, commitment and complementarity, as well as co-orientation. Intervention outcomes included enhanced mutual understanding in the CAR, enhanced self-awareness, enhanced team relationships, and adaptive interpersonal behaviour change. These outcomes were associated with a shared awareness between coaches and athletes of their Enneagram personality type traits and motivations. Coach-athlete relationship quality was further enhanced by re-constructing coaches’ and athletes’ personal narratives based on self-descriptions of Enneagram type strengths, and a redefinition of individuals’ core motivations to incorporate adaptive interpersonal behaviour change.
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- Date Issued: 2018
Development of a community pharmacy experiential learning programme in a South African context: a design research approach
- Authors: Kritiotis, Lia Costas , Thesis Advisor
- Date: 2018
- Subjects: Pharmacists -- Training of , Experintial training , Community development -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/17481 , vital:28353
- Description: Application of the design research approach to devise, develop and optimise an experiential learning programme and adaptation of the Volunteer Functions Inventory (VFI) to understand community pharmacists’ motives, are unique contributions to the global pharmacy education setting. This study generated new theory, in the form of substantive and procedural claims (design principles) regarding experiential learning programmes and preceptor and student motivation in a South African pharmacy educational context, which can be added to the existing international landscape and more importantly, plant the foundational seeds of insight that can be utilised as guiding tools by other South African pharmacy faculties.
- Full Text:
- Date Issued: 2018
Development of high capacity lithium-manganese-rich cathode materials xLi2MnO3•(1-x)LiMn0.5Ni0.5O2 for lithium ion batteries
- Authors: Rapulenyane, Nomasonto
- Date: 2018
- Subjects: Lithium ion batteries , Electrochemistry Lithium cells
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/34766 , vital:33442
- Description: In this study, a facile synthesis method was developed to produce layered-layered cathode materials with the formula xLi2MnO3•(1-x)LiMO2 (M= Ni and Mn) referred to as lithium-manganese-rich materials for lithium ion batteries. The prepared materials displayed high capacity ≥200 mAh/g at a current density of 20 mA/g in the voltage range of 2.0 V to 4.8 V. In particular the cathode material prepared at pH 10.0 delivered a high initial discharge capacity of 266 mAh/g at 20 mA/g current density and maintained a discharge capacity ≥220 mAh/g at 50 mA/g after 50 cycles. The synthesis method was used to further investigate the effect of lithium ratio in the layered-layered material. Li1+xMn0.6Ni0.2O2, x= 0.2, 0.25, 0.3 and 0.4 cathode materials were produced respectively. The BET surface area analysis results showed that Li1.3Mn0.6Ni0.2O2 material had comparatively higher surface area to the other cathode materials and also delivered good electrochemical results. XPS showed that the cation distribution is affected by the increase in lithium ratio, the Mn4+ percentages decreased significantly with an increase in lithium ratio. All materials peaks deconvoluted into two peaks namely Mn4+ and Mn3+, Li1.3Mn0.6Ni0.2O2 had the highest percentages of the stable Mn4+ 70.8%. Further investigation focused on the effect of the sintering temperature on the structure and the electrochemical performance of Li1+xMn0.6Ni0.2O2, x= 0.25, 0.3 and 0.4 cathode materials. X-ray diffraction showed the same patterns for all cathode materials sintered at 700˚C, 800˚C and 900˚C. Rietveld refined results however, showed that the increase in the sintering temperature, results in a decrease in the Li2MnO3 component percentage in the layered structures. Scanning electron microscopy images further proved that the particle size increases with increasing temperature. The charge–discharge tests of coin cells demonstrated that the materials sintered at 800˚C delivered higher discharge capacities above 200 mAh/g at 20 mA/g current density when compared to the materials made at the lower temperatures. Lastly the cathode material prepared at pH 10.0 was further evaluated in a cell using lithium titanate oxide Li4Ti5O12 as anode material. The cells delivered an initial discharge capacity of 213 mAh/g at 20 mA/g within a voltage range 3.3V-0.5V. The coin cells developed in this work delivered good cycling performance.
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- Date Issued: 2018
Development of InSb/GaSb quantum dots by MOVPE
- Authors: Ahia, Chinedu Christian
- Date: 2018
- Subjects: Semiconductors , Quantum electronics Organometallic compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23382 , vital:30537
- Description: There has been an increasing interest in the modification of semiconductor band structures through the reduction of their dimensions, which simultaneously increases the band gap energy of the material and gives rise to flexibility in device properties. Advances in III-V antimony (Sb) based semiconductor fabrication have triggered the quest for extension of the emission/absorption wavelength range of this family of compounds for optoelectronic devices operating in the mid-infrared region of the electromagnetic spectrum. An interesting material system for mid-infrared (MIR) applications is indium antimonide (InSb) quantum dots (QDs) within a gallium antimonide (GaSb) matrix. However, its band alignment and emission wavelength has been the subject of some interest and controversy over the years. This study focuses on the development of InSb/GaSb QDs by metal organic vapour phase epitaxy (MOVPE). The samples were grown on different substrates using various growth parameters in order to vary the size, density and aspect ratio of the dots. Interfacial growth interruptions while flowing various source precursors through the reactor were investigated in order to influence the chemical termination of the surface, and hence the resulting strain in the structures. The samples were characterized using photoluminescence spectroscopy, scanning probe microscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Likewise, the band alignment, energy levels, and carrier wave functions of the samples in this work were modelled theoretically using the nextnanomat software (version 3.1.0.0). A comparison of growth on two different GaSb substrates [(100) 2° off towards <111>B ± 0.1ᵒ and (111) ± 0.1ᵒ] using similar growth conditions yielded a higher dot density on the (100) substrate compared to the (111) substrate. This was attributed to the presence of terraces/atomic steps induced by the misorientation on the (100) substrate, which invariably gives rise to increased adsorption and an enhanced sticking coefficient of adatoms. Studies on the influence of a buffer layer on the morphology of uncapped dots showed that the shape and size of the dots are sensitive to the thickness of the buffer layer. In some case a corrugated buffer surface resulted, which introduced order in the arrangement of the dots, which formed preferentially inside the troughs. An increase in the V/III ratio from 1.0 to 3.0 was found to reduce the areal density of the QDs, while an analysis of the diameter histograms showed a narrowing of the size distribution with an increase in V/III ratio. The larger size distribution at low V/III was ascribed to the increase in indium species and the increased indium adatom migration length. This leads to increased dot density and nucleation sites, and thus triggers an increase in the conversion of tiny QDs into thermodynamically more suitable larger dots via coalescence. However, as the V/III ratio increased, the number of indium adatoms available for growth on the surface reduced, which automatically led to a decrease in the migration length of indium species which is unfavourable for the production of nucleation sites and to a decrease in dot density. Low growth rates were found to be beneficial for the growth of a high density (~5×1010cm-2) of QDs. Photoluminescence (PL) analysis of the capped samples at low temperature (~10 K), using an excitation power of 2 mW, showed a PL peak at ∼732 meV. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV was noticed. This emission typically persisted up to 60–70 K. An increase in the number of InSb QD-layers, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the PL lines, together with an enhancement in the strength of the PL emission. However, high resolution transmission electron microscopy (HRTEM) of the capped dots revealed the formation of an InGaSb quantum well-like structure, ∼10 nm thick, which was responsible for the PL signal mentioned above. The absence of QDs in the capped sample was attributed to inter-diffusion of Ga and In during the deposition of the cap layer, giving rise to a quantum well (QW) instead of the intended QDs. The presence of threading dislocations and stacking faults were also observed in the TEM micrographs of the samples containing multilayers, which can account for the fast quenching of the PL emission with increasing temperature from these samples. Theoretical simulations of the band alignment, wave functions and energy levels were in good agreement with the data collected from the PL spectra of the samples.
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- Date Issued: 2018
Dimensions of a memorable experience within a marine tourism context
- Authors: Jonas, Altouise Glowdean
- Date: 2018
- Subjects: Customer relations -- Management , Customer relations Relationship marketing Tourism -- Environmental aspects Coastal zone management -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30540 , vital:30958
- Description: Worldwide, businesses are operating in an environment which is continuously changing, forcing them to adapt their strategies in order to remain competitive. Two changes were of particular importance to this study. Firstly, businesses are faced with an increasing demand from consumers for experiences as opposed to products and services. Secondly, consumers are demanding experiences that are not just ordinary, but are unique and memorable. As one of the largest and most diverse industries globally, tourism offers a multitude of tourist activities. Marine tourism is one of the oldest, most popular and fastest developing types of tourism globally. Marine tourism has also become popular in South Africa. This popularity might be attributed to the country’s expansive coastline and to it being home to one of the most diverse marine systems in the world. Marine tourism makes significant contributions to South Africa’s economy. More benefits can be derived from this lucrative type of tourism if attention is given to the design and provision of marine tourism experiences that go beyond average experiences, and become memorable experiences. The reason for conducting this research was to provide the South African tourism industry, and marine tourism operators in particular, with information which might assist them in designing and staging memorable experiences. Such memorable experiences could result in a competitive advantage and enable the operators to attract more customers, which in turn, will benefit the individual operators, the industry as a whole, and ultimately, the South African economy. The study focused on three marine tourism activities, namely; shark-diving, visits to marine protected areas and whale-watching. Eight dimensions, namely; Delight, Hedonism, Involvement, Knowledge, Meaningfulness, Novelty, Refreshment and Social-Interaction were identified as prospective dimensions of a memorable experience within a marine tourism context. v The study employed purposive, convenience and snowball sampling to identify potential respondents. Primary data was collected by means of an online survey and paper-based self-administered questionnaires. Four hundred and forty-four useable responses were received. The results of the empirical study showed a positive correlation between all the dimensions and memorable experience for each of the three activities and for all the activities combined. A second order factor analysis showed that the eight dimensions loaded onto two factors. The resulting factors were named as the Affective Domain (consisting of Hedonism, Refreshment, Delight and Involvement) and the Cognitive Domain (consisting of Knowledge, Social- Interaction, Meaningfulness and Novelty). A positive relationship was found between the Affective Domain and Memorable Experience and also between the Cognitive Domain and Memorable Experience. The Cognitive domain showed a stronger relationship with Memorable Experience than what the Affective Domain did, for all the activities combined. The memorability of an experience in the case of all three activities combined can, firstly, be improved by Involvement. This is closely followed by the following dimensions in the Affective Domain; Delight, Hedonism and Refreshment. Under the Cognitive Domain the factor which is most important for improving memorability of all the activities combined is Meaningfulness, followed by Knowledge, Novelty and Social-Interaction. Finally, structural equation modelling confirmed a model representing the eight experience dimensions (Delight, Hedonism, Involvement, Knowledge, Meaningfulness, Novelty, Refreshment and Social-Interaction) and identified the relationships between the dimensions and Memorable Experience. This study makes four important contributions. Firstly, it contributes to the under-researched topic of marine tourism in South Africa. Secondly, it adds to the literature on memorable tourism experiences, specifically memorable marine tourism experiences and provides a measurement instrument and framework for further research. Thirdly, the study identifies and confirms that ‘delight’ is an important dimension of a memorable marine tourism experience. vi Lastly, a model was developed which can be used by marine tourism operators to enhance their strategies, operations and facilities which will enable operators to achieve a sustainable competitive advantage.
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- Date Issued: 2018
Evaluating the impact of energy policies on sustainable development in South Africa
- Authors: Julius, Ibitoye Oyebanji
- Date: 2018
- Subjects: Energy policy -- South Africa , Sustainable development -- South Africa Renewable energy sources -- South Africa Sustainable living -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30440 , vital:30944
- Description: The unachieved targets of the Millennium Development Goals (MDGs) at the end of 2015 by some developing countries including South Africa, lead to the evolution of the Sustainable Development Goals (SDGs). Ensuring access to sustainable, affordable, and modern energy is one of the 17 SDGs that the countries are expected to achieve before the end of 2030. Green growth is an important strategy for attaining this goal and a pathway to achieving the other goals. Therefore, an empirical study of the impact of energy policies on sustainable development is pertinent. Despite the importance of such research, there exists a gap in the literature relating to green growth and sustainable development from the SDGs point of view. This study fills the existing lacuna by developing an intertemporal holistic model which allows a study of the impact of energy policies on sustainable development in relation to the SDGs. Specifically, this thesis employs the Autoregressive Distributed Lag (ARDL) and Toda-Yamamoto approaches to analyse the long-run relationship and direction of causality respectively between green growth policies and sustainable development in South Africa from 1984 to 2016. This research provides insights into the importance of green growth for factors such as deforestation, fuel exports, energy imports and agricultural development, thus adding to the existing literature on the impact of renewable energy on a country’s social, environmental and economic conditions. Results from the analysis of the long-run relationship between green growth and macroeconomic variables, indicate a positive unidirectional relationship between changes in green growth policies and gross capital formation. This finding suggests that adopting green growth policies leads to increased investments. In contrast, green growth was found to have a negative effect on national income (gross domestic product). However, the Granger causality tests do not establish causality between these variables. Although green growth policies stimulate investments, high start-up costs associated with the implementation of these policies may mean that the resultant higher investments are yet to be translated to higher income levels in the South African economy. The findings indicate a boost in the South African balance of payment within the study period iv iv as evidenced by the positive long-run relationship between green growth policies and fuel exports. Additionally, the results indicate that green growth energy policies have assisted in improving the resilience to international oil price shocks as shown in the negative and significant long-run relationship between green growth and energy imports. With regard to environmental variables, results suggest a substitutability effect between green growth policies and the consumption of non-renewable energy. However, no evidence is found on the impact of green growth policies on the levels of deforestation and carbon dioxide(CO2) emissions, as well as natural resource depletion. In relation to the social variables, adoption of green growth policies was found to lead to improved educational quality, with causality running in both directions. This finding supports the feedback hypothesis. Similarly, green growth policies had a positive impact on agricultural development, again with causality established in both directions. The outcome of the long-run relationship between green energy consumption and unemployment shows that the green growth policies is yet to have a significant impact on unemployment reduction in South Africa. Green growth also has an insignificant and indirect relationship with GDP per capita; this result was affirmed by the absence of causality between GDP per capita and green energy consumption. This research not only makes contributions to the literature on the relevance of green growth policies for achieving economic, social and environmental sustainability, it also suggests possible policy implications which highlight the need for adoption and continued implementation of green growth policies in developing countries such as South Africa.
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- Date Issued: 2018
Exploring lecturer preparedness to apply a critical approach to curriculum implementation: a case study
- Authors: Sathorar, Heloise Helena
- Date: 2018
- Subjects: Teacher participation in curriculum planning
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/31786 , vital:31828
- Description: This study sought to investigate lecturer preparedness to apply a critical approach to curriculum implementation and to establish their willingness or unwillingness to engage as transformative intellectuals with their students and to apply a problem-posing education in their classrooms. The study investigated lecturers’ critical pedagogy dispositions as well as their orientations towards applying a critical approach to curriculum implementation. A comprehensive literature review was done regarding the concept critical pedagogy, its tenets and principles as well as what it entails to apply a critical approach to curriculum implementation. In particular the literature review highlighted the responsibilities of a transformative intellectual as well as the requirements of applying a problem-posing education. The study was conducted through a constructivist lens and theoretically framed by referring to specific critical pedagogy concepts. The study is located in the interpretive paradigm and a qualitative research approach was followed. In particular, an instrumental case study analysis was used as research method. The sample consisted of 20 permanently employed lecturers from the School for Initial Teacher Education in the Faculty of Education at Nelson Mandela University who volunteered to participate in an online investigation regarding their critical pedagogy dispositions as well as their orientations towards applying a critical approach to curriculum implementation. The findings of the study revealed that lecturers generally have a positive disposition towards critical pedagogy as well as towards the application of a critical approach to curriculum implementation. Despite this positive picture there were pockets of resistance towards critical pedagogy and the application of a critical approach to curriculum implementation. Finally, the study proposes a critical approach model that could be employed to enhance lecturer preparedness to apply a critical approach in their classes.
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- Date Issued: 2018
Factors affecting effective ecological restoration of Portulacaria afra (spekboom)-rich subtropical thicket and aboveground carbon endpoint projections
- Authors: Van der Vyver, Marius Lodewyk
- Date: 2018
- Subjects: Restoration ecology , Plant conservation -- South Africa Portulacaria afra -- South Africa Shrubs -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23250 , vital:30468
- Description: Among the requirements to achieve effective ecological restoration on a landscape scale are a scientific underpinning, strong adaptive management and the setting of realistic endpoints. Efficacy and success depend on a complex interplay of factors of both local and regional influence. Biome-wide restoration experiments are rare, but valuable for evaluating efficacy of different protocols according to local context. The Thicket-wide Plot (TWP) experiment was initiated by the Subtropical Thicket Restoration Programme to inform landscape-scale ecological restoration of degraded Portulacaria afra (spekboom)-rich Subtropical Thicket. Thirteen different planting treatments of Portulacaria afra (spekboom) truncheons were planted as replicated rows on 0.25 ha fenced plots across the distribution range of spekboom-rich thicket habitat to better establish effective restoration protocols. I used a rule-based learning ensemble algorithm to evaluate 60 different predictors that potentially impact effective restoration, covering a range of climatic, topographic, edaphic, ecological and management related factors observed at 227 of these TWP plots. Percentage survivorship and aboveground biomass carbon sequestration rate (ABCsr) were taken as proxies for efficacy derived from subsequent monitoring data gathered 2 - 5 years after establishment, and a new allometric model I developed for spekboom. I found herbivory and identification of target habitat the two most important predictors of restoration efficacy, both well within the control of the practitioner. Highest survivorship and ABCsr were associated with larger truncheons planted deeper. The only exception to this pattern was found amongst the two smallest size truncheon categories. The application of external rooting hormone or watering treatment to truncheons were found of no significance to effective restoration, while all the pruned treatments were, in association with lesser planting depth, found to be significantly less effective than untreated truncheons planted deeper. When the restoration protocol is optimal (largest truncheons planted deepest in target habitats and protected from herbivory), my results show higher annual carbon sequestration rates (1.46 - 3.7 t C ha−1 yr−1 in aboveground biomass) than most older restoration sites that have been identified as benchmarks of success. In order to project ABC endpoints, I generated 40 new species-specific allometric models and used them to estimate biomass and carbon of intact and degraded stands on five sites spread out across the region. The highest AGC for stands in both intact and degraded states were estimated at 42.96 t Cha−1 and 12.98 t C ha−1 respectively, and the lowest at 26.32 t C ha−1 and 2.52 t C ha−1. Large canopy dominant (LCD) species contributed the largest AGC portion at three intact stands. The second largest portion was recorded for spekboom. The difference between paired stands on each sample site ranged between 23.8 and 32.8 t C ha−1, which provide a realistic target for biome-wide restoration that, when adopted together with current protocols, may be reached within three decades of inception.
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- Date Issued: 2018
Habitat use of important juvenile fish species in temperate Earnestine nursery areas with notes on feeding ecology and historical shifts to assist with conservation planning, South Africa
- Authors: Nel, Larize
- Date: 2018
- Subjects: Mariculture -- South Africa , Fishes -- Ecology -- South Africa Fishes -- Food -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32904 , vital:32396
- Description: Estuaries are among the most productive ecosystems worldwide as they provide important refuge and feeding areas for the juveniles of many marine species, many of which have recreational importance. The use of these nursery areas by juvenile fishes in South Africa are in need of further investigation and many critical areas such as shallow water creeks and vegetated habitats remain understudied. By using mixed-methods, estuarine fish assemblages were assessed in five permanently open estuaries in the Eastern Cape Province of South Africa. A total of 81 428 comprising 24 families and 40 species of fishes were sampled by means of a 50 m seine net (12 mm mesh) along the length of these systems that comprised of six equidistant sites during the summer recruitment period (October - December) of 2014 and 2015. A higher catch per unit effort (CPUE) was recorded in 2014 (68 875) compared to the following year where a decline of approximately 82% was observed in the catch (12 553) for all estuaries except the Kromme Estuary. Catches were mainly dominated by the marine estuarine dependent sparid, Rhabdosargus holubi and the solely estuarine clupeid, Gilchristella aestuaria. Species compositions and catch abundance with regards to historical catches showed that the abundance of many marine estuarine dependent juveniles as well as important recreational species have declined within these systems and are mainly attributed to marine overfishing and the exploitation of undersized individuals in estuarine nurseries. Juvenile fishes that occur in these estuaries utilize a range of vegetated habitats ranging from salt marsh creeks, Zostera capensis beds, Spartina maritima and previously unexplored Phragmites australis areas. Sampling was achieved by using passive, double-winged, six-hooped fyke nets, 1 mm mesh size that was secured in placed on the nocturnal flood tide at each inundated vegetated and adjacent unvegetated habitat types. Higher catches were frequently recorded in vegetated areas for solely estuarine and marine estuarine dependent species and supports evidence of plasticity within these habitats. In general, the previously unstudied reed, P. australis showed the highest species richness and abundance of juvenile fishes overall, followed by, Z. capensis and the intertidal salt marsh species, S. maritima. These findings relate to many international trends on the value of vegetated areas as refugia for young fishes in estuaries. Fishes were also showing evidence of feeding and sheltering in these areas. By using conventional stomach contents and stable isotope methods (δ13C and δ15N signatures) on the abundant R. holubi in previously selected vegetation sites, it was clear that this species has a significant reliance on any of these habitats as their diets was largely comprised of a mixture of epiphytic algae and aquatic macrophytes. In addition, the diet of larger individuals (>80 mm) showed a greater component of invertebrates in previously unexplored habitats, which proves their omnivorous diet related to ontogenetic niche use. Knowledge of fine-scale habitat use by fishes is essential for conservation planning as exclusion zones can be optimised to limit anthropogenic influence on nursery use patterns in fishes. The availability of shallow water habitats (<60 cm) was assessed as an additional driver to explain the species diversity and richness of juvenile fishes within the lower reaches. These habitats are known as important nursery habitats providing numerous marine and estuarine spawned fishes with adequate refuge and food supply. This shallow water volume was measured by means of a two-man kayak using both the spring high and low tides in the lower reaches of these systems to assess juvenile assemblages. It was clear from the results that aquatic vegetation significantly adds to the volume of these areas and as a result, much greater fish density and species richness were observed. Generalized additive models showed that marine spawned species were particularly reliant on the availability of this shallow water along with submerged vegetation and additional environmental variables. The presence of structurally submerged vegetation typically characterized within shallow estuarine waters is commonly believed to reduce predation risk resulting in elevated densities of biota. Based on the current stock status and percentage of pristine breeding stock, five fish species classified as collapsed/overexploited was consistently found within these systems with an additional 14 species currently classified as exploited/vulnerable. Based on the current species richness and diversity, available habitat cover and knowledge regarding important recreational species, priority areas that require some form of legal protection in order to meet potential biodiversity targets, could be identified. It is a legal requirement in South Africa that all estuaries require management plans that should be based on good knowledge of priority habitats for fauna and flora. The identification of estuarine protected areas is seen as a mechanism for protecting a representative sample of the biodiversity accompanied by a complete range of environmental gradients and habitat types at a reasonable scale in order to maximize the protection of estuarine species.
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- Date Issued: 2018
In vivo toxicological evaluation of peptide conjugated gold nanoparticles for potential application in colorectal cancer diagnosis
- Authors: Adewale, Olusola Bolaji
- Date: 2018
- Subjects: Nanostructured materials -- Toxicology , Colon (Anatomy) -- Cancer Rectum -- Cancer
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/50133 , vital:42050
- Description: Colorectal cancer (CRC) is among the leading cause of cancer-related deaths in South Africa and worldwide. Efforts are being made at finding improved diagnostic tools, as early detection (before metastasis) is a major factor in CRC treatment. Colonoscopy is the most reliable detection method, but is a specialised and expensive procedure, which is invasive, not readily available and not patient-friendly. There is a risk of developing interval cancers, as colonoscopies are performed every 10 years after the age of 40. The development of non-invasive, cost efficient and readily available diagnostic tools to CRC, which can be performed at more regular intervals, using tumour-targeting molecular imaging agents, is of urgent attention. Gold nanoparticles (AuNPs) possess several physicochemical properties, including ease of synthesis, biocompatibility, and the ability to be conjugated by ligands or biomolecules such as polyethylene glycol (PEG) and peptides for improved stability, tissue targeting and selectivity. These factors potentiate the role in biomedical applications, including cancer theranostics. Conjugation of AuNPs with a targeting molecule (e.g. antibody or peptide) is directed against cancer cell receptors. The peptides, p.C, p.L, and p.14, bind to CRC cells in vitro. Conjugation of AuNPs with these peptides should be investigated for CRC diagnosis in vivo, as it is hypothesised to allow examinations at shorter intervals through imaging techniques. This could reduce the risk of interval cancers, but before developing this novel tool, in vivo toxicity evaluations are essential. This study was therefore aimed at investigating the short- and long-term toxicological effects of a single intravenous injection of peptides (p.C, p.L, and p.14) conjugated to AuNPs in a healthy rat model. Citrate-capped AuNPs were synthesised by the citrate-reduction method, and conjugated with each peptide (biotinylated) using a combination of PEG (99% PEG-OH and 1% PEG-biotin) as a stabilising agent and linker, via biotin-streptavidin interaction. Healthy male Wistar rats were intravenously injected with 14 nm citrate-AuNPs, PEG-, p.C-PEG, p.L-PEG, and p.14-PEG-AuNPs (100 μg/kg body weight), and the control rats were injected with phosphate buffered saline. The animals were monitored for behavioural, physiological, biochemical, haematological and histological changes, as well as inflammatory responses. Phase 1 rats were sacrificed 2 weeks post-injection to determine the immediate or acute toxicity of the AuNPs, while phase 2 animals were sacrificed 12 weeks post-injection, to investigate the delayed or persistence toxicity of the AuNPs. Results revealed no significant toxicities with the citrate, PEG-, p.C-PEG and p.14-PEG-AuNPs over 12 weeks post-exposure, as evidenced by biochemical assays such as serum marker enzymes, liver and kidney function markers, and cholestatic indicators; haematological parameters; oxidative stress markers; and histopathological examinations. P.L-PEG-AuNPs, however, caused significant toxicity (p<0.05) to rats, as evidenced by increased relative liver weight, increased malondialdehyde levels, and total white blood cell counts 2 weeks post-exposure when compared to the control group. This was, however, reversed during the 12 weeks post-exposure. Further, there were no evidence of inflammatory responses, using pro-inflammatory markers including phospho interleukin 18 (IL-18) and interferon-γ (IFN-γ), as indicated by immunohistochemical staining of the liver, spleen, kidney and colon of rats 2 weeks post-injection of AuNPs. Citrate, PEG-, p.C-PEG, and p.14-PEG-AuNPs did not induce immediate, acute or persistent toxicity, while p.L-PEG-AuNPs induced a transient acute toxicity. It can be concluded that 14 nm spherical citrate-AuNPs at 100 μg/kg body weight is a good candidate for biomedical applications, and as a suitable carrier for diagnostic and/or therapeutic molecules. Combination of 99% PEG-OH and 1% PEG-biotin is an appropriate option for stabilising AuNPs in biological environment, and conjugating secondary diagnostic or therapeutic biomolecules or agents to citrate-capped AuNPs. Peptide-conjugated AuNPs are suitable for the development into a diagnostic tool for CRC in vivo.
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- Date Issued: 2018
Interest rate liberalisation and economic growth in SADC countries
- Authors: Moyo, Clement Zibusiso
- Date: 2018
- Subjects: Southern African Development Community , Economic development -- Africa, Southern Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/22791 , vital:30087
- Description: The pioneers of financial liberalisation, McKinnon (1973) and Shaw (1973) argue that inter-est rates determined by market forces have a positive effect on economic growth rates. Inter-est rates that are kept at low levels through the intervention of a central bank discourage sav-ings and capital accumulation, and distort the allocation of resources. Interest rate liberalisa-tion results in higher real interest rates which could have a positive effect on savings, invest-ments and economic growth (Ang & McKibbin 2007). Interest rate liberalisation also reduces capital flight and encourages capital inflows by increasing return for investors which supple-ments domestic investments. Shaw (1973) argued that interest rate liberalisation promotes financial development by encouraging savings and increasing the availability of funds for lending purposes. The study provides an empirical analysis of the channels through which interest rate liberalisation impacts on economic growth in SADC countries for the period 1990 to 2015. The study is motivated by the concerns on the impact of interest rate liberalisation on eco-nomic growth in the period after the 2008-’09 global financial crisis as well as concerns that interest rate liberalisation increases the likelihood of financial crises. Higher interest rates resulting from interest rate liberalisation may increase the likelihood of financial crises by encouraging risk-taking on the part of banks in an attempt to take advantage of higher returns. Authorities in most countries have reduced interest rates in an attempt to boost aggregate demand, which is expected to speed up the recovery from the crisis. However, the lowering of interest rates may result in a decrease in savings and investments, which are the main drivers of long-term economic growth. Real interest rates below equilibrium may encourage banks to take more risks in their lending practices in order to earn higher returns which may result in an increase in non-performing loans. The influence of interest rates on financial crises has thus received considerable attention since the onset of the 2008-’09 global financial crisis and this thesis contributes to the literature by determining how interest rates impact on economic growth in SADC countries and whether interest rate liberalisation increases the likelihood of financial crises. The study examines the relationship between interest rate liberalisation and economic growth through different channels. These include savings and investments, capital flows and finan-cial development. The study uses the Pooled Mean Group (PMG) estimator proposed by Pesaran et al (1999) to estimate the effect of interest rate liberalisation on economic growth through the abovementioned channels. The study also examines whether interest rate liberalisation increases the likelihood of financial crises. This is estimated using the logit model, due to the binary nature of the dependent variable. The results provide limited support for the McKinnon and Shaw hypothesis. Interest rate liberalisation has a positive effect on economic growth through higher savings and investments. Interest rate liberalisation has a positive outcome on capital inflows, which indicates that the prospect of earning higher returns encourages foreign investors to invest in the domestic economy. However, capital inflows do not enhance economic growth. This could be due to the low levels of human capital in SADC countries. Interest rate liberalisation boosts financial development through higher savings and invest-ments. However, financial development has a negative effect on economic growth because of the link between financial development and financial crises. The results show that interest rate liberalisation decreases the likelihood of financial crises directly, however, it increases the probability of financial crises indirectly through financial development. This suggests that the major cause of financial crises in the region is the low levels of institutional quality and lack of adequate supervisory frameworks to monitor the functioning of the financial system. Therefore, the results imply that the negative impact of interest rate liberalisation may outweigh the positive effect of higher savings and investments in SADC countries. A number of policy recommendations can be drawn from the study. Liberalisation of interest rates has a positive effect on economic growth through savings and investments. However improving the levels of institutional quality is vital for preventing financial crises. Interest rate liberalisation may not have a direct influence on financial crises, but higher levels of fi-nancial development emanating from higher interest rates increase the likelihood of financial crises. Therefore, a sound monitoring framework is necessary for the benefits of financial liberalisation to be realised. Also, investment in education, training and research and development is a necessity so as to increase levels of human capital, which in turn may allow the region to reap the benefits of capital inflows.
- Full Text:
- Date Issued: 2018
Investigation of the potential separation of isomers and related compounds using host compound (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol
- Authors: Pohl, Pieter Lourens
- Date: 2018
- Subjects: Chemistry, Organic , Clathrate compounds Thermal analysis
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23131 , vital:30432
- Description: In this study, we investigated the potential of a host compound, (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT), for use in the separation of isomers and related compounds using host-guest chemistry. The title molecule, DMT, is composed of a butane chain bearing hydroxyl moieties on the terminal carbons and methoxy moieties on the two internal, chiral carbon atoms. In addition, there are two phenyl rings on each of the terminal carbons. The synthesis of DMT was carried out by subjecting the diester of naturally-occurring optically active tartaric acid to a Grignard reaction employing phenylmagnesium bromide. Subsequent methylation of the secondary hydroxy groups with dimethyl sulfate afforded DMT. The resulting host molecule was investigated for its inclusion abilities by crystallizing with a number of potential aromatic, aliphatic and alicyclic guests such as toluene, aniline, nitrobenzene, anisole, cyclohexane, ethyl acetate and ethanol. Host:guest ratios were determined by means of 1H-NMR spectroscopy. Of the hosts investigated, DMT favoured a host:guest ratio of 2:1 for all included guests investigated. It complexed with most non-polycyclic aromatic guests as well as cyclohexane, cyclohexene and cyclohexanone. It was not able to include short chain or branched alcohols such as methanol, ethanol or 2-propanol, or other hetero-aliphatic or hetero- cyclic compounds such as diethyl ether, acetonitrile, morpholine or dioxane. Competition inclusion experiments were performed in which DMT was crystallized from equimolar and non-equimolar binary, ternary and quaternary mixtures of appropriate guests. The mother liquor mixtures and resultant crystals were subjected to GC-MS analysis in order to determine whether DMT showed discriminatory behaviour towards the guests from a mixture. It was observed that DMT was able to differentiate between related compounds, for example, the host preferred to include N,N-dimethylaniline compared with N-methylaniline and aniline. The host also discriminated against isomers, for example, p-xylene was preferentially included over o-xylene and m-xylene, while o-cresol was included in preference to p-cresol and m-cresol. Single crystal X-ray analysis was used to investigate the host–guest interactions responsible for guest inclusion, as well as to discern reasons for the host’s selective behaviour. X-ray data for the inclusion complexes indicated that each complex was isostructural, crystallizing in the monoclinic C2 crystal system. A pair of 1,3- and 2,4- intramolecular hydrogen bonds, as well as intramolecular non-classic hydrogen bonds between adjacent ortho-aromatic hydrogens and hydroxy moieties was a significant stabilizing factor for the geometry of the host. Guests were held within discrete cavities in the crystal lattice, and experienced only π–π stacking, CH–π interactions and other short contacts. Thermal analyses were used to determine the relative thermal stabilities of the complexes, and these data compared to the selectivity preference of DMT, obtained from the competition experiments, in order to assess the reasons for any discriminatory behaviour. Finally, Hirshfeld surface analysis data was used to determine if the thermal stability of the complexes was related to the number and type of interactions between host and guest.
- Full Text:
- Date Issued: 2018
Investigation of the thermo-chemical behaviour of coal-algae agglomerates
- Authors: Baloyi, Hope
- Date: 2018
- Subjects: Biomass energy , Coal -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23913 , vital:30642
- Description: There is a growing research interest in the co-processing of biomass and coal, with the aim of addressing the negative attributes associated with the thermal processing of coal alone. Biomass feedstocks are regarded as a clean, renewable source, and the co-utilization of biomass feedstocks with coal is deemed to have a potential to reduce emission of pollutants (i.e. NOx and SOx) and volatile organic compounds (VOC’s). Moreover, biomass are thermally reactive and thus facilitate the conversion of coal during co-processing. Biomass material and coal are two autonomous fuel materials with different chemical characteristics and have a dissimilar thermal behaviour making it difficult to achieve chemical interaction between the two solid fuels to contribute to the formation of products. Coalgae® Technology developed at the Nelson Mandela University, involves the biological treatment of coal fines by adsorbing live microalgae biomass (in slurry form) onto waste coal fines to form coal-microalgae agglomerates. This new innovative approach seeks to integrate bio-based feedstock into coal thermal processing and to improve the utilization and thermal efficiency of coal fines as well as the interaction between the volatile components of biomass and coal during thermal processing (e.g. devolatilization), thereby overcoming some of the challenges that confront the co-processing of coal and biomass. Coal fines are low-ranked coals, generally characterized by high contents of sulphur, high ash yields, low calorific values and poor thermal reactivity, and these attributes limits the thermo-chemical processing of the coal fines. Therefore, this investigation was undertaken to assess the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorbing live microalgae slurry at varying ratios onto coal fines. For this purpose, the effects of adsorbing microalgae at varying ratios on the chemical characteristics and thermal behaviour of coal fines under pyrolytic conditions were investigated. The primary aim was to assess whether the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorption of live microalgae onto fine coal, is substantively modified compared to a simple additive model of the original coal and pre-dried microalgae biomass samples. Results obtained from the proximate analyses performed on an Eltra Thermo-gravimetric analyzer (TGA) thermostep, have shown that the adsorption of microalgae slurry onto coal fines does not possess greater influence in improving the yield of volatiles and ash in coal fines than can be expected from a simple additive model of the original raw materials. Based on the ultimate analyses results, it was found that the adsorption of microalgae slurry resulted in a systematic reduction in the sulphur content, a notable increase in the hydrogen and oxygen contents, however, no significant disparities were found between the measured ultimate properties of coal-microalgae agglomerates as compared to the theoretically-expected ultimate properties from a simple linear combination of parental coal and microalgae biomass. Assessment of the thermal behaviour of parental samples and coal-microalgae agglomerates involved the use non-isothermal (40-900ºC, 20 K/min) thermogravimetry under inert conditions. It was found that the adsorption of microalgae slurry onto coal fines resulted in an improved thermal reactivity of coal fines, although, did not affect the overall pyrolysis characteristics of the coal fines. Comparison of the thermal profiles (measured and calculated TG/DTG curves), revealed that the yield of volatile products during the pyrolysis of coal-microalgae blends do not exceed the expected volatile yields from a simple combination of coal and microalgae biomass. These results suggest that there was no positive or accelerative synergistic interaction between volatile components of adsorbed microalgae and coal fines during pyrolysis. Mild pyrolysis of raw coal and coal-microalgae performed in a fixed-bed reactor furnace (450ºC), resulted in improved yields of Fossil-Bio crude (FBC) oil (derived from coal-microalgae pyrolysis), at increased biomass ratio compared to coal tar. FBC Oil was found to contain relatively high contents of oxygen, hydrogen, and low sulphur content than coal tar. GC-MS analyses showed the presence of a heterocyclic compounds (i.e. Indole and 2, 6 dimethyl pyridine) in the FBC oil and these were not identified in the coal tar. Furthermore, high boiling compounds such as Flourene, pyrene and pentacosane were identified in the coal tar, however not identified in the FBC oil. Simulated distillation results showed notable differences between the FBC oil and coal tar in terms of the distribution of boiling point fractions particularly, high boing point components. Semi-devolatilized chars derived from coal-microalgae agglomerates showed substantial degree of decarboxylation and dehydrogenation compared to the coal chars.
- Full Text:
- Date Issued: 2018
Linking people’s needs, preferences and values to ecosystem services provided by marine phytoplankton of Algoa Bay, South Africa
- Authors: Snow, Bernadette
- Date: 2018
- Subjects: Marine phytoplankton -- South Africa -- Port Elizabeth , Marine biology -- Research Biodiversity conservation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/33363 , vital:32669
- Description: Marine, coastal and ocean development has gained impetus around the globe and in particular along Africa’s coastal states. A socio-ecological systems framework approach was adopted to explore marine and coastal socio-ecological systems in Algoa Bay, situated in the Eastern Cape, South Africa a Bay with a rich history steeped in culture and diversity. Phytoplankton biodiversity was determined for the Bay to characterise aspects of the marine environment in Algoa Bay. The policy landscape for South Africa was also analysed to characterise the governance landscape and identify if the policies, legislation and frameworks adopted and applied would support socio-ecological systems thinking and support equitable development of marine and coastal resources. Positives raised by manager are the general positive attitude and pro-environmental value system. To understand how people within the Nelson Mandela Bay Municipality value the marine and coastal environment, their knowledge of phytoplankton and services provided, governance knowledge, attitudes towards the future of the socio-environment landscape and value positions that would identify pro-environmental behaviour of the communities surveyed. Loss of marine and coastal environments and services would be a direct threat to spiritual and cultural practices and beliefs of the amaXhosa. Further access was a driving theme in this study and therefore development and conservation efforts need to heed the value and importance of having access to the marine and coastal environment, not only for sustaining livelihoods but for religious and leisure experiences. Size fractionated biomass was determined to describe the contribution of different cell size assemblages to the overall productivity of Algoa Bay. The analysis showed a general dominance of microplankton cell sizes with the picoplankton not contributing much towards the overall biomass of the period analysed. Cell size of the phytoplankton species provides an indication of the environmental changes, together with contribution towards biomass. Species that bloom also change the productivity of the system, for example a diatom bloom will increase productivity more so than a dinoflagellate bloom. Cell size will influence response of phytoplankton to environmental changes and how phytoplankton adapts physiologically to stressors such as climate change. However in the context of studies linking biodiversity to a socio-ecological framework, size fractionated data is not required and overall productivity and diversity of the system is better suited for this type of study. The direct link between the ecological and social data is the application of the information for management of the ecosystem and as an early warning system. The information learnt from the managers and community also highlights the need for a shared approach to gathering knowledge and learning about the world around us.
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- Date Issued: 2018
Local tourism governance of destination marketing organisations
- Authors: Bartis, Hugh Henry
- Date: 2018
- Subjects: Place marketing Tourism -- Marketing
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/17799 , vital:28455
- Description: Globally tourism is one of the biggest industries and its role is considered key in economic development. In South Africa, tourism is one of the main economic drivers. Thus, tourism contributes to the gross domestic product, generates foreign exchange and provides sustainable employment opportunities. In order to facilitate local economic development (LED), local destination marketing organisations (DMOs) need to ensure that their operations are geared towards optimising the economic advantages related to tourism growth and development. As a result the DMOs must be strategic and well-managed. One way of achieving this is to ensure that the board of directors and specifically the non-executive directors (NEDs) practise good governance. In South Africa, three (3) types of DMOs are found, namely those that are funded by local government and incorporated into the municipality. The second type of DMOs is funded by the private sector. The third type of DMOs is those funded by both the local government and the private sector. In this case, the DMO has an agreement with the local government in terms of what their mandate is and what the agreed outcomes would be. A board of directors, comprising both executive directors (EDs) and nonexecutive directors (NEDs) is responsible for the governance of the local DMO. The main research problem of the study is the attributes and experience of the nonexecutive directors that serve on the boards of DMOs in accordance with developmental standards of best practices. In order to address the main problem, the following research objectives were formulated: To identify best practice by examining the literature as to how NEDs are prepared to serve on boards of both listed and non-listed organisations. To determine whether any policy frameworks provide guidance to NEDs serving on DMOs in South Africa. To examine whether any training or preparatory programmes exist specifically for NEDs in DMOs. To investigate whether NEDs should have specific attributes that would improve their governance of DMOs. To develop a set of recommendations that would assist NEDs to play a more effective role when executing their responsibilities. In order to address these research objectives, a quantitative research methodology was adopted sampling all the DMOs in South Africa that could be identified and were governed by a board of directors. For this purpose, a self-completed questionnaire was distributed to the board of directors of DMOs and specifically the non-executive directors. The results of the study indicated that no guidelines existed that DMOs could follow to better prepare the NEDs of local DMOs. Furthermore, no policy frameworks provide guidance to NEDs serving on local DMOs. The only guidelines that exist are generic guidelines of the King IV Report for NEDs of listed and non-listed organisations. In addition, Pike (2016:108) listed a number of characteristics of good governance. The study also revealed that no training or preparatory programmes exist for the NEDs of local DMOs. Finally, the study highlighted five (5) attributes that NEDs consider as critical in fulfilling their obligations. These include the empowerment of NEDs, the commitment of NEDs, communication with NEDs, job satisfaction of the NEDs and the need for NEDs to understand policy frameworks relevant to their tasks.
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- Date Issued: 2018
Microfinace and poverty alleviation in Uganda
- Authors: Ben, Ssembajjwe
- Date: 2018
- Subjects: Microfinance -- Uganda , Economic development -- Uganda Economic assistance, Domestic Poverty -- Economic aspects -- Uganda
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23624 , vital:30588
- Description: Microfinance began in Uganda in the early 1990s as a response to the failure by formal financial institutions to extend financial services to the poor because of the high transaction costs involved. These microfinance institutions provide financial and non-financial services to the poor in order for the poor to generate incomes and consequently alleviate poverty. The advent of microfinance institutions was not accidental but rather in response to the people’s needs and they have therefore been beneficial for the people of Uganda. Because of that, several MFIs have been initiated to help the poor. Although many services are provided, the study focused on credit services. As most of the MFIs have to balance the business goal of profit maximization and the social goal of poverty reduction, the main objective of this study was to explore whether microfinance in Uganda is an effective tool for poverty alleviation. The study was conducted in four districts, namely Mukono, Mpigi, Wakiso and Luwero. Using random probability sampling, a sample of 170 was drawn from a pool of 300 MFI clients. and all of them responded. MFI officials were also interviewed. A total 136 officials were obtained from 47 MFI branches. The study used descriptive methods of analysis, a Likert scale to derive means, as well as a Principal Component Analysis technique. Analysis of variance (ANOVA) was used to detect if there were any statistically significant differences among the demographic variables used in the study. A Probit Regression Model was used to determine the impact of certain variables drawn from Principal Component Analysis (PCA) on poverty in Uganda. The results obtained proved that MFIs in general are effective in combating poverty in Uganda. Variables that are significant in poverty reduction through loan use are land, education, employment, household incomes and occupations of the respondents, loan sizes and improved livelihoods. Despite the positive impact of MFI loans in Uganda, the MFIs are faced with a number of challenges. The results from the interviews with the MFI officials indicated that MFIs are challenged by increasing competition, bad debt, multiple borrowings by clients, and information asymmetry. The study recommended reduced interest rates on agricultural, education and business loans. The public must also be sensitised about borrowing and there should be increased monitoring and supervision of clients, improved assessment of creditworthiness, and government should ensure an enabling environment and encourage group loans. Effort should be exerted to create employment opportunities. The study also recommended improvement in market intelligence and to be alert in gathering information on client profiles. it was recommended that microloan insurance and savings must be encouraged, operational costs be reduced, portfolios be expanded to increase loans and outreach must be maximised. Lastly, the thesis put forward some potential areas for further studies.
- Full Text:
- Date Issued: 2018
Molecularly imprinted polymeric materials for adsorptive removal of nitrogen compounds from fuel oils
- Authors: Abdul-Quadir, Muhammad Sabiu
- Date: 2018
- Subjects: Polymerization , Organonitrogen compounds Nitrogen compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23426 , vital:30542
- Description: The deleterious effects of refractory polyaromatic hydrocarbons found in fuels such as organonitrogen compounds (quinoline, carbazole and its alkylated derivatives) are such that they emit NOx to the environment when combusted, thereby reducing air quality. These compounds also deactivate the catalyst used during fuel refinement and in catalytic converters of cars. Hydro-denitrogenation (HDN), a process currently being employed in petroleum refineries to eliminate organonitrogen compounds in fuels, is limited in treating these refractory compounds. Hence, this thesis describes the use of two separate complimentary approaches for the removal of organonitrogen compounds in fuel such as oxidative denitrogenation and adsorptive denitrogenation. The catalyzed oxidation of fuel oil model nitrogen containing compound, quinoline to quinoline N-oxide, was conducted under batch and continuous flow microreactor at 70°C by using tert-butylhydroperoxide (t-BuOOH) as oxidant and silica supported V2O5 as catalyst, followed by the selective adsorption of the quinoline N-oxide. An overall conversion of 62% quinoline N-oxide was observed. Quinoline-N-oxide in model fuel was absorbed by employing synthesized molecularly imprinted 2,6-pyridine-polybenzimidazole (2,6-PyPBI) nanofibers, 86% of quinoline-N-oxide was removed to give an adsorption capacity (qe) of 4.8 mg/g. DFT calculations to study the interactions of quinoline-N-oxide vs 2,6-PyPBI indicated that: (i) hydrogen bonding (through amino group of 2,6-PyPBI and oxygen atoms of the quinoline-N-oxide), (ii) pi-pi stacking and (iii) extensive number of van der Waals interactions took place. Several oxygenates from N-compounds were produced, thus, complicating the fuel matrix. Therefore, there is a need to move towards adsorptive denitrogenation. Poly-2-(1H-imidazol-2-yl)-4-phenol (PIMH) imprinted microspheres was prepared by suspension polymerization using 2-(2’-hydroxy-4-ethenylphenyl) imidazole as a functional monomer and ethylene glycol dimethacrylate as a crosslinker in the presence of various organonitrogen compounds (templates) to produce 2-(2’-hydroxy-4-ethenylphenyl) imidazole (PIMH). Imprinted microspheres show selectivity for various target model nitrogen-containing compounds with adsorption capacities of 6.8 ± 0.2 mg/g, 6.3 ± 0.3 mg/g and 5.8 ± 0.3 mg/g for quinoline, pyrimidine and carbazole, respectively. Adsorption selectivity increased in the order of quinoline (αi-r = 136.9) ˃ pyrimidine (αi-r = 126.2) ˃carbazole (αi-r = 86.3), when naphthalene was selected as a reference compound. Though, imprinted microspheres displayed excellent nitrogen compound removal both in model and real fuel, there was a need to improve the adsorbent adsorption capacity for N-compounds in fuel through the fabrication of imprinted nanofibers. Molecularly imprinted poly-2-(1H-imidazol-2-yl)-4-phenol nanofibers was prepared by electrospinning of 2-(2’-hydroxy-4-ethenylphenyl) imidazole (PIMH) in the presence of various organonitrogen compounds. These imprinted nanofibers show selectivity for various target model nitrogen-containing compounds with adsorption capacities of 11.7 ± 0.9 mg/g, 11.9 ± 0.8 mg/g and 11.3 ± 1.1 mg/g for quinoline, pyrimidine and carbazole, respectively. Adsorption selectivity increased in the order of pyrimidine (αi-r = 258.8) ˃ quinoline (αi-r = 235.5) ˃ carbazole (αi-r = 168.2). It further displayed excellent nitrogen removal in real fuel. The use of polybenzimidazole (PBI) nanofibers showed selective adsorption of organonitrogen compounds as imprinted sorbent also displayed high selectivity for their target model nitrogen-containing compounds with adsorption capacities of 11.4 ± 0.4 mg/g, 11.9 ± 0.2 mg/g and 10.9 ± 0.7 mg/g for quinoline, pyrimidine and carbazole respectively. Adsorption selectivity increased in the order of pyrimidine (αi-r = 241.5) ˃ quinoline (αi-r = 237.6) ˃ carbazole (αi-r = 170). Thermodynamic parameters obtained from isothermal titration calorimetry (ITC) revealed that quinoline-PIMH/PBI and pyrimidine-PIMH/PBI interactions are exothermic in nature, while carbazole-PIMH/PBI is endothermic in nature. DFT calculations indicated that π-π interactions/stacking and hydrogen bond interactions took place between N-compounds (carbazole, quinoline and pyrimidine) and adsorbent (PIMH and PBI). A significant reduction in the quantity of nitrogen containing compounds in hydrotreated fuel was observed (peak area reduction) when adsorbents (PIMH and PBI) was employed, however, the complex nature of organonitrogen compounds in fuel complicate the structure/function approach on MIPs for targeting these unwanted compounds.
- Full Text:
- Date Issued: 2018
Motivation for landscape stewardship as a driver of change-Garden Route, South Africa
- Authors: Heider, Lisa
- Date: 2018
- Subjects: Social ecology , Environmental psychology Conservation (Psychology)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30116 , vital:30826
- Description: Stewardship, as portrayed in much of contemporary literature is considered as a key to the sustainability challenges of the biosphere. In disciplines which regard sustainability in the context of Social Ecological Systems (SES), stewardship is associated with the goal of building resilience through the informal governance structures that dictate how the landscape is utilized. These disciplines lack a better integration of individual roles and responsibilities as they relate to their daily interactions with the environment. Formally initiated stewardship can evoke maladaptation, in other words the attempts to conserve a specific natural assets in one particular locality can shift the problem of degradation or exploitation to another place or point in time. This is because the individual, as an inevitable driver of unsustainability, has not been addressed. What is needed is the knowledge of strategies which resolve human disconnection from nature and the biosphere, through a greater focus on the individual motivational scale. In Chapter 2, which consists of a literature review of recent stewardship discourses, I extract alternative theories which consider individual motivation and subjectivity as the underlying drivers of resilience. These include knowledge about Sense of Place, and theories from Conservation Psychology. Basic Human Value theory is also presented as a possible entry point for societal transformation through individual motivation. These ought to inform conservation interventions with mechanisms which truly grasp unsustainability at its roots. This is a place-based, qualitative study where the results assist in interrogating the question: How does individual motivation for stewardship mediate socialecological trajectories of change? The context of the study and the methods used to generate my research findings are presented in Chapter 3 and 4. The Garden Route provides the place-based context for this research and is situated in the Western Cape Province of South Africa. The region is home to diverse cultures representative of Western and indigenous regions who meet and negotiate what it means to care for the environment. The area is biologically rich and ecologically highly sensitive to current trajectories of development, fragmentation and global change. Mixed methods and a qualitative approach was used to answer three sub-questions: (1) Which theories facilitate greater understanding of transformative stewardship pathways? (2) How can a transformative pathway be recognized? and (3) How can transformative pathways be pursued? One method used in this study is a photo-voice technique, which is coupled with self-directed journaling and in-depth interviews. Other sources of data include communication and engagement, observations iii and focus groups. I apply a content analysis to the transcribed qualitative data to resolve the research questions. Research results are presented in Chapter 5. In this empirical chapter I present three competing meanings of stewardship and visions for change held by individuals in the Garden Route. The three meanings are described as: protect nature from human influence (Nature despite People); work together and communicate (Nature for People/Nature and People); and be the change you want to see in this world (People in Nature). The variable which best describes the differences in visions is Critical Connectivity. Resilience in a SES is critically dependent on three levels of connectivity in stewardship. Firstly, individuals’ consciousness of being interrelated and interdependent within a community of life; Secondly, expressions in the physical landscape which promote the connectivity of ecological systems as well as the connectivity between people and nature. Thirdly, Connectedness with the Biosphere, which means that the boundaries of the planet and the functioning of the life-supporting earth system are considered in behaviours. I use Basic Human Value theory to test whether it can explain how the differences between and commonalities within the three groups arise. The results support the theory, suggesting that Basic Human Values underlie individual motivation for stewardship. However, inconsistencies and shortcomings of Basic Human Value theory became evident. I identified new values and value combinations which were not made explicit in the framework. These emerged due to my in-depth qualitative approach, as opposed to the common quantitative uses of the framework. The qualitative approach allows for values to emerge inductively and it elicits nuances of individual value interpretations that the definitions of Basic Human Values do not depict. In the second part of the empirical chapter, I present evidence of maladaptive and transformative stewardship pathways in the Garden Route. A maladaptive pathway is one in which individuals’ expression of care for the environment undermines Critical Connectivity and transfers vulnerabilities in the SES. A transformative pathway is one in which individuals pro-actively invest into Critical Connectivity and enhance resilience. The differences in these pathways are directly related to the differences in motivation. iv The findings of this research reveal that stewardship is the act of ‘place creation’ which is motivated by unique and nuanced differences in basic values and individual consciousness. Recognizable features of transformative and maladaptive stewardship pathways are discussed in Chapter 6. I present a conceptual model that critically evaluates stewardship. This model firstly assists researchers and practitioners to become alert to early warning signs of maladaptive pathways. Secondly, it informs them of potential leverage points for interventions which can induce sustainability transformations. I then apply this model to discuss transformative and maladaptive pathways against the backdrop of my findings and the literature. The elements which emerged as critical in this assessment are risk perceptions, stewardship meaning, connectivity with nature, connectedness with the biosphere, relationship with place, sustenance and identity. Different configurations of each indicator help explain the different pathways. Lastly, I discuss the role of Basic Human Values in each of the pathways. I compare how the motivational orientation towards self-enhancement and self-transcendence, or towards openness to change and conservation, play roles in SES resilience. This discussion brings to the surface the fact that transformative stewardship rests on a combination of these four value categories. In contrast, the absence of self-transcendent values and the presence of power, security and conformity underlie the motivation for maladaptation. I leave the reader with suggestions for interventions which have become relevant as a result of my study. Policy, media, conservation agencies and science shape meanings of stewardship, portray social norms and hence must motivate Critical Connectivity. Transformations can be achieved by targeting changes in values which must include autonomy, universalism, benevolence and spirituality. I discuss how policy and planning, communication, marketing and education can lever transformation through mechanisms identified in my research. Chapter 7 concludes this research with a reflective summary of the academic and practical contributions my study has made for stewardship discourses and for the management of SES resilience in local landscapes. I provide recommendations for further research, as they apply to socio-political change in Post-Apartheid South Africa. I end the concluding chapter by encapsulating my research finding in future scenarios for the Garden Route in the face of change, which namely relate to abrupt and uncertain environmental change, immigration, population growth and implications for spatial planning, and the Garden Route Biosphere Reserve. v In Chapter 8, I provide a reflection of this research. This entails foremost a reflection of how I have accounted for four quality criteria in social research, which are namely dependability, credibility, conformability and transferability. I end the chapter with the limitations and outline of scope of my study..
- Full Text:
- Date Issued: 2018
Narcissistic defenses and alienation in the life of Howard Hughes: a case study
- Authors: Sandison, Alida
- Date: 2018
- Subjects: Hughes, Howard -- 1905-1976 , Narcissism Self psychology Personality disorders
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/35038 , vital:33609
- Description: Narcissism is a personality configuration which has both normal and pathological personality expressions. It is associated with a very broad field of literature and theoretical formulations, put forward to understand it. To add to this knowledge base, the aim of the research was to explore and describe narcissistic defenses and the consequent alienation of others within the narcissistic personality configuration. The aim was attained through the exploration of the life of Howard Hughes, by examining the interplay between Kernberg’s Object Relations Theory (1974; 1975; 1976; 1980; 1984; 1992; 2001) and Hughes’s lived experiences. Hughes was chosen as the subject as he is renowned for being an eccentric billionaire who was revolutionary in his effect on the world, but concurrently disturbed within his personal pathologies. The study took the form of a case study. Data was collected using Yin’s (1994) guidelines for data collection, which include using multiple sources of evidence, creating a case study database, and keeping and maintaining a reliable chain of evidence. Data was furthermore collected and analysed using Miles and Huberman’s (1994) strategy of data analysis which consists of three steps, namely data reduction, data display, and conclusion drawing and verification. Research findings confirmed the presence of primitive defense mechanisms associated with the lower level pathologies described by Kernberg within Hughes’ patterns. Findings confirmed the defense mechanisms as alienating others. Learnings produced were presented in a model to be used in clinical practice to support others in interaction with narcissistic individuals. Steps outlined included, understand, decontaminate and reconstruct, reaffirm reality, and find something positive.
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- Date Issued: 2018
On the development of ZnO nanorods on silicon substrate for light-emitting diode applications
- Authors: Djiokap, Stive Roussel Tankio
- Date: 2018
- Subjects: Zinc oxide , Chemical reactions , Compound semiconductors
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/29973 , vital:30802
- Description: The interest in zinc oxide (ZnO), a promising material for blue/ultraviolet light emitting devices, arises from its large exciton binding energy (60 meV). The main challenge associated with this promising compound semiconductor, however, arises from the difficulty to achieve stable and/or reproducible p-type doping. Since silicon (Si) technology still dominates the semiconductor industry, the objective of this thesis is to probe into the possibility of using ZnO nanorods (NRs) on p-type silicon for opto-electronic devices. ZnO NRs have been grown on seeded Si, as well as on nickel oxide (NiO) and aluminum nitride (AlN) coated Si, using a two-step chemical bath deposition (CBD) process. Various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM), have been used to characterize the samples. The electrical characteristics of the heterojunction between the substrate and the ZnO nanostructures were evaluated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. SEM and XRD studies have confirmed that, irrespective of the orientation of the Si substrate (Si (100) and Si (111)), the two-step CBD process yielded NRs that crystallised in the wurtzite structure and exhibited a hexagonal shape. Most of the rods developed perpendicularly to the surface of the substrate, with the orientation and distribution of the rods dictated by the seed layer density. Similarly, irrespective of the substrate, the luminescence of the ZnO nanostructures is dominated by near band edge (NBE) emission in the UV region (~ 3.29 eV) and deep level emission (DLE) in the visible region (2 eV to 2.6 eV). Annealing at moderate temperatures (~ 300 °C) increased the NBE emission and decreased the DLE. The removal of surface adsorbed impurities and enhanced defect passivation by hydrogen are responsible for these changes. The diode characteristics of the ZnO/Si heterojunction was studied by I-V and C-V measurements. Rectification was observed when the Si substrate had a relatively low acceptor density of ~1016 cm-3, while diodes produced on substrate with p ~1018 cm-3 were ohmic. From the C-V analysis the donor density in the ZnO was deduced to be ~1018 cm-3. In the case of rectifying junctions, thermionic emission did not dominate the charge transport. The carrier transport mechanism was therefore probed by the temperature dependent I-V xiii measurements (100 K to 295 K). Defect-assisted multistep tunneling was deduced to dominate in the n-ZnO/p-Si diodes at low forward bias. The band alignment between n-ZnO and p-Si predicts a much smaller barrier for electrons than for holes at the interface, which results in recombination on the Si side of the junction for a forward-biased diode. NiO intermediate layers (formed on Si by the thermal oxidation of Ni) were used to reduce electron injection from ZnO into Si. Scanning probe microscopy (SPM) and XRD analysis showed that while the grain size of the poly-crystalline NiO increased with NiO film thickness, the orientation and distribution of the subsequently grown ZnO nanorods were unaffected by the underlying NiO layer. Also, the photoluminescence response of the ZnO rods remained unchanged. I-V measurements did illustrate rectifying behaviour, with both the forward and reverse currents strongly decreased due to the resistive nature of the NiO. In another attempt at confining electrons to the ZnO side of the junction, AlN-coated Si (111) was used as a substrate for ZnO nanorods. CBD parameters that normally yield nanorods resulted in a plate-like architecture of the ZnO. By modifying the ZnO seed density on the AlN/Si substrate, the rod-like morphology could be recovered. Both the forward and reverse current decreased in these diodes. From studies aimed at identifying the transport mechanism it was concluded that trap-assisted tunnelling, resulting from a high density of defects in the seed layer, dominates in these devices. In conclusion, while no ZnO electroluminescence could be achieved from any of the devices, this study provides insight into the transport mechanisms in n-ZnO/barrier/p-Si heterostructures and highlights the importance of the heterointerface quality for light emitting devices.
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- Date Issued: 2018