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.
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- Date Issued: 2018
Rural-urban migration and its impact on rural development in Nigeria
- Authors: Abizu, Odion Stanley
- Date: 2018
- Subjects: Rural development Rural-urban migration -- Nigeria Rural poor
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/13815 , vital:39714
- Description: This thesis focuses on the developmental impact of rural-urban migration in Nigeria. While, recognising the negative impact of rural-urban migration, the study argues that in order to benefit internal migrants as well as rural development, there must be a paradigm shift to focus on how the benefits of migration on development can be achieved. It is proposed that rural-urban migration occurs as a response to economic, education, health, social and environmental factors. The challenges confronting rural areas are urban bias development paradigm pursued by the successive governments resulting in rural underdevelopment that exacerbates the rural urban disparity. And the neglect of agriculture in rural areas resulting from the discovery of oil in Nigeria. The study revealed that flawed policies adopted by successive Nigerian governments led to joblessness, entrenched social inequality and opportunities. One of the outcomes of these short-sighted policies was rural underdevelopment, which accelerated rural-urban migration in Nigeria. However, the study also demonstrates that the income flows from the migrants to the various rural households has contributed to improvement in the living standard of the households. The fragmentary approaches to rural development that is currently the case in Nigeria would not generate the required level of development and growth needed in the rural communities to improve the living standard. Thus, there is need for a policy framework in Nigeria, which would encourage the private sector to play a vital role in contributing their part in the provision of infrastructural facilities in the rural communities. Although this thesis is a case study of the impact of rural-urban migration on rural development in Nigeria, it can serve to appreciate the role migration can play in promoting development both in rural and urban areas in Nigeria and other Saharan Africa countries.
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- Date Issued: 2018
A multi-stakeholder approach to productivity improvement in the South African construction industry
- Authors: Adebowale, Oluseyi Julius
- Date: 2018
- Subjects: Labor productivity , Construction industry -- Labor productivity Construction industry -- South Africa Construction industry -- Management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/19597 , vital:28902
- Description: As poor productivity in construction continues to constitute a setback to projects’ success in different countries of the world, the situation in South African construction is no exception. Poor productivity on construction projects and its detrimental impact on project objectives have continually resonated for decades. As a result, several strategies, interventions, and measures that aimed at improving productivity in the construction sector have been proposed. Nevertheless, the phenomenon importunately creates a major challenge on construction projects, and by extension, the construction industry especially in developing countries. Even when construction management literature acknowledged the commonalities in productivity influences, the practice of addressing construction productivity influences as separate entities has gained much relevance over the years. Taking into perspective, the multidisciplinary and complexity inherent in construction, a systemic approach to addressing construction productivity influences is fast becoming essential. This study addressed productivity-influencing factors by considering factors that are related to rework, shortage of construction resources, constructability, political, socio-economic, working environment, welfare conditions, disputes, planning and training. Consequently, the interdependencies of the most significant productivity-influencing factors in South African construction was developed in the form of a qualitative model. The study adopts the underlying assumptions of the quantitative approach, but also accepts some qualitative data. With regards to the subject of enquiry, the paradigm of the research is positivism which consists of realists’ ontological prescriptions and objectivists’ epistemological prescriptions. Site engineers, site managers, and site supervisors working for cidb registered contractors in four South African provinces constitute the sample stratum. Statistical Package for the Social Sciences (SPSS) version 24 was used to analyse the data gathered from these project participants; both descriptive and inferential statistics were used. Descriptive statistics was used to summarise and describe the data obtained, while inferential statistics in the form of analysis of variance, T-test, and Tukey post hoc test were adopted. The study reported the most significant factors which negatively influence productivity on South African construction projects as inadequate workers’ skills, defective workmanship, the practice of awarding contracts to lowest bidders, political activities resulting in industrial action, inadequate contractors’ experience in project planning, payment delays by contractors, and corruption. Furthermore, it was found that contractors largely share similar perceptions regarding the factors that constrain productivity growth in South African construction. The approximate level of labour, material, and plant productivity on South African construction projects is 50.4%, 72.9%, and 62.0% respectively, while the approximate multifactor productivity was estimated as 61.8%. The study concluded that productivity has a considerable relationship with time and cost and a less potent relationship with quality. Based on the research findings, contractors’, consultants’, clients’ and government qualitative intervention models were proposed while recommendations towards improving South African construction productivity were made. The study recommended the reinvention of the apprentice training system to develop skills in construction, the involvement of stakeholders in improving workers’ skills, improved collaboration between the construction industry and higher institutions of learning regarding curricula development, adequate supervision of construction activities to mitigate the propagation of rework on construction projects, character in leadership, and integrity of project stakeholders.
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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
Synthesis, characterization and evaluation of photophysical and electrochemical properties of ruthenium(II) complexes for dye-sensitized solar cells
- Authors: Adjogri, Shadrack John
- Date: 2018
- Subjects: Ruthenium Ruthenium compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/17828 , vital:41363
- Description: Eight series of thirty (30) novel heteroleptic ruthenium(II) complexes were designed, synthesized and spectroscopically characterized, with the following general molecular formulae as [Ru(bdmpmar)(H2dcbpy)(NCS)]+, [Ru(bdmpmar)(vpdiinp)(H2dcbpy)]2,+, [Ru(bdmpmar)(vpbpp)(H2dcbpy)]2+,[Ru(H2dcbpy)2(N^)(NCS)]+, [Ru(H2dcbpy)2(N^)2]2+, [Ru(H2dcbpy)(N^)2(NCS)2], [Ru(H2dcbpy)(N^)(NCS)3]– and [Ru(vptpy)(H2dcbpy)(N^^^)]2+ where bdmpmar is a tridentate ligand of N,N-bis(3, 5-dimethylpyrazol-1-yl-methyl) aromatic organic compound (such aromatic organic compounds(Ar) are anthranilic acid, 4-methoxy-2-nitroaniline, aniline, toluidine, cyclohexylamine and anisidine), vpdiinp represents a monodentate ligand of 11-(4-vinylphenyl)diindeno[1,2-b:2’,1’-e]pyridine, vpbpp represents a monodentate ligand of 4-(4-vinylphenyl)-2.6-bis(phenyl)pyridine and vptpy represents a tridentate ligand of 4’-(4-vinyl)-2,2’:6’,2’’-terpyridine. Meanwhile, N^ represents any of the monodentate ligands of either vpdiinp or vpbpp and (N^^^) represents any of the monodentate ligands either of vpdiinp or vpbpp or NCS as disclosed in series VIII. The complexes were characterized by conductivity measurement, solubility, melting point, UV-Vis, PL, FTIR (ATR), NMR, Cyclic and square wave voltammetry. Nine chelating ligands, comprising of six (6) tripodal chelating ligands, two (2) vinyl monodentate ligands and one (1) vinyl tridentate ligand, were used for the synthesis of ruthenium(II) complexes ATR-FTIR spectra of all the ruthenium(II) complexes measured as solid samples, exhibited fine resolution IR bands in region between 3473-3438 cm-1 of carboxylic group in H2dcbpy. The bands in the range 3040-2950 cm-1 were ascribed to C-H bond stretching for the CH3 groups. The coordination of NCS group in the sphere of ruthenium(II) complexes related to series I, IV, VI VII and one compound of series VIII was investigated by ATR-FTIR spectroscopy. Bands in the range of 2116-2106 cm-1 and 777-770 cm-1 are ascribed to the respective N=C and the C=S bond stretching vibration which confirms the N-coordination of the SCN group. For all the complexes, the stretching vibration of Ru-N bonding was between 466 and 411 cm-1 due to coordination of the nitrogen atoms of the ligands to ruthenium central metal atom. The introduction of the two vinyl monodentate ligands (vpdiinp and vpbpp) in the coordination sphere of [Ru(bdmpmar)(vpdiinp)(H2dcbpy)]2+, [Ru(bdmpmar) (vpbpp)(H2dcbpy)]2+, [Ru(H2dcbpy)2(N^)(NCS)]+, [Ru(H2dcbpy)2(N^)2]2+, [Ru(H2dcbpy)(N^)2(NCS)2], [Ru(H2dcbpy)(N^)(NCS)3]– and [Ru(vptpy)(H2dcbpy)(N^^^)]2+ respectively, all related to series II, III, IV, V, VI, VII and two compounds of series VIII ruthenium(II) complexes, has been studied using the 1H and 13C NMR spectroscopy techniques. The 1H NMR spectra of series II-VII and the two compounds of series VIII of the ruthenium(II) complexes show multiplets in the aromatic region above 6 ppm due to the presence of either vpdiinp or vpbpp ligand, situated in different magnetic environment. However, no splitting pattern was observed in series I and part of VIII complexes possibly due to the absence vinyl monodentate subunits (vpdiinp and vpbpp) in series I and one of compound in series VIII ruthenium(II) complexes show no signals of complex splitting patterns. Carbon-13 NMR spectra data of series I to VIII ruthenium(II) complexes show most resonance signals range in the aromatic region of (δ 116.54-199.63ppm) corresponding to the molecular formulation of ruthenium(II) complexes incorporating 4,4-dicarboxy-2,2’-bipyridine, bdmpmar, vptpy, vpdiinp or vpbpp and NCS ligands respectively, depending on the intrinsic ligand variations. Carbon-13 NMR spectra data of series I, IV, VI VII and one compound in VIII show resonance peaks within the range 130-135 ppm are ascribed to NCS ligand confirming the presence of N-coordinated thiocyanate. Cyclic voltammograms of series I-IV and VI-VIII complexes display ruthenium-based oxidative peaks and the pyridines ligand-based reductive peaks. The redox behavior of complexes 4-12, 14-16, 18-20, 24-26 and 30 is dominated by the Ru(II)/R(III) redox couple in region (E1/2 between 0.53 and 1.18) and the pyridines ligand-based redox couples in the region between (E1/2 between −0.25 and −1.45). The photophysical property studies of the Ru(II) complexes are determined through the acquisitions of the absorption spectra, which tends to have profound effect on the short circuit current of DSSC. The absorption maxima were tuned by the introduction and variation of six (6) tripodal chelating ligands, two (2) vinyl monodentate ligands and one (1) vinyl tridentate ligand. From the studies, the results show that series IV, V, VI, VII and VIII complexes of molecular formula [Ru(H2dcbpy)2(N^)(NCS)]2+, [Ru(H2dcbpy)2(N^)2]2+, [Ru(H2dcbpy)(N^)2(NCS)2]2+, [Ru(H2dcbpy)(N^)(NCS)3]2+ and [Ru(vptpy)(H2dcbpy)(N^^^)]2+ respectively, have higher and multiple local absorption maxima near-IR region than the complexes of series I, II and III of molecular [Ru(bdmpmar)(H2dcbpy)(NCS)]2,+, [Ru(bdmpmar)(vpdiinp)(H2dcbpy)]2,+, [Ru(bdmpmar)(vpbpp)(H2dcbpy)]2,+respectively.
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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
The role of family structure and financial socialisation in influencing students' financial capabilities
- Authors: Antoni, Xolile Lucas
- Date: 2018
- Subjects: Finance, Personal , Families -- Economic aspects Finance -- Social aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/21505 , vital:29531
- Description: This research used three theories to develop a theoretical framework that investigated the role of family structures and financial socialisation in influencing students’ levels of financial knowledge, attitudes, self-efficacy and behaviour (financial capabilities). It also examined the mediating role of family financial situation in the relationship between the family structure and the mechanisms of financial socialisation. The theories of consumer socialisation, family financial socialisation and family structure model, guided the development of a proposed theoretical framework and development of five major hypotheses. To answer the research questions of the study and test the hypotheses, this study followed a quantitative survey research design. Undergraduate students in the Faculty of Business and Economic Sciences completed 350 questionnaires. Using exploratory factor analyses results, the theoretical framework was updated, and statistical relationships tested. Simple regression analysis results showed that students who were born or raised in an intact family structure reported more financial socialisation in terms of the mechanisms of financial socialisation than students who were born or raised in non-intact family structures. Simple regression results showed that intact family structures had positive significant relationships with four of the six components of the mechanisms of financial socialisation. Furthermore, intact family structures had negative significant relationships with two components of the mechanisms of financial socialisation. Multiple regression results showed four components of the mechanisms of financial socialisation (teaching and monitoring, reinforcement of financial behaviour, modelling of financial behaviour and financial conflict) had positive significant relationships with financial capabilities. The components of financial socialisation agents (peers and media) had positive significant relationships with three components of financial capabilities (financial behaviour, money is respect and freedom, and money is good). In addition, family financial situation partially mediated the relationship between intact family structure and three components of the mechanisms of financial socialisation, namely, parental teaching and monitoring, modelling of financial behaviour and parental relationship. Furthermore, family financial situation perfectly mediated the relationship between intact family structures and one component of the mechanisms of financial socialisation (reinforcement of financial behaviour). Three components of the mechanisms of financial socialisation (parental teaching and monitoring, reinforcement of financial behaviour and modelling of financial behaviour) also perfectly mediated the relationship between intact family structure and one component of financial capabilities, namely, financial behaviour. Similarly, one component of the mechanisms of financial socialisation (parental teaching and monitoring) also perfectly mediated the relationship between intact family structure and one component of financial capabilities (financial self-efficacy). These results assisted in the development of a new empirically tested model to investigate the role of family structure and financial socialisation in influencing students’ financial capabilities. This study showed that family structures was an important variable that should not be excluded in financial planning as it influenced all the components of the mechanisms of financial socialisation. Financial socialisation agents also had an influence on financial capabilities and, thus, the parental financial socialisation should not be investigated in isolation. It was also important to identify the mechanisms of financial socialisation as seen in this study, as the components of the mechanisms had different influences on students’ financial capabilities. For this study, parental teaching and monitoring, reinforcement of financial behaviour and modelling of financial behaviour proved to be the most important components of the mechanisms of financial socialisation, which ultimately influenced students’ financial capabilities. This study has proved that family structures and financial socialisation influence the financial capabilities of students. To improve financial capabilities of students, parents should increase their level of modelling of financial behaviour and decrease the level of secrecy about money in the household. Parents should also instill positive financial attitudes in students, monitor their financial behaviour, and reinforce positive financial behaviour. This study contributes to the much-needed body of knowledge in financial planning by showing through empirical results that family structure has an influence on the components of the factor mechanisms of financial socialisation, and the factor financial capabilities. As little information exists to explain these relationships, this study makes a valuable contribution to new knowledge in this area.
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- 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
Towards a community based conservation strategy for wetlands in Uganda
- Authors: Barakagira, Alex
- Date: 2018
- Subjects: Conservation of natural resources , Wetland conservation -- Uganda Wetlands -- Uganda -- Management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23902 , vital:30640
- Description: Conservation of natural resources in Uganda focuses primarily on protected areas, including savannah national parks, mainly for conserving big game and forests, for controlling the harvest of commercially valuable timber resources, with less concern for wetlands. Later, policies and legislation in Uganda favoured agricultural production rather than the conservation of wetlands, a situation that culminated in their degradation. In a bid to counter the effects of wetlands degradation, Wetland Management Agencies were created. These agencies excluded the input of members of the local communities who reside in the wetlands environs. Local communities were not consulted on matters concerning management and conservation strategies, a situation that may have escalated the problem of wetlands degradation. Local knowledge is needed for the effective management and conservation of the wetlands and it is essential that local communities are included in decision making. This research study is more of an initiative for providing information that may be essential for the formulation of a community based conservation strategy for wetlands in Uganda. The study aimed to identify and characterize activities carried out by members of the local communities in wetlands found in central and western Uganda that are responsible for their progressive degradation; to assess the performance of existing Wetlands Management Institutions towards protection and conservation of wetlands in Uganda; to ascertain whether the acts and policies that have been promulgated for the protection of wetlands in Uganda have been adhered to by members of the local communities and to evaluate three community based conservation case studies with two vastly different outcomes in order to come up with the community-based conservation principles Ugandan communities may need to adopt to achieve sustainable utilisation and conservation of wetland resources. To achieve the objectives stated above, the researcher used a multi-disciplinary methodology that required several areas of expertise and sources of information. Hence, to accomplish the study, primary sources of data that included quantitative and qualitative data were collected from the study participants by means of a questionnaire survey, key informant interviews and direct observations. Secondary sources of data centred on published Ugandan acts and policies; textbooks; case study articles and journal articles. The study revealed a host of activities in which members of the local community are involved that have led to the degradation of the wetlands in Uganda. These include but are not limited to crop cultivation, dairy farming and unsustainable wetland resource harvesting. A number of other reasons for the degradation of the wetlands include unclear ownership of the wetlands, unclear wetland boundaries and a lack of awareness of the indirect benefits wetlands provide for members of the local communities. The study disclosed that wetlands management institutions have not been effective in the protection and conservation of wetlands in Uganda, mainly due to political interference and inadequate funding for the institutions’ conservation activities. The acts and policies that were promulgated for the protection and conservation of wetlands have been selectively implemented in some places and in others completely ignored, culminating in the degradation of the wetlands. The study revealed that effective community based conservation of wetlands in Uganda includes: initiation of the planning, implementation, monitoring and evaluation of all wetlands activities being borne by members of the local community; government introducing alternative income-generating activities aimed to reduce over-reliance on wetland resources and education of the local communities regarding the community-based projects’ objectives in order to garner their support. Recommendations emanating from this study are that the Land Act should be amended to specify a particular land tenure system, preferably freehold, which may promote the conservation of wetlands in Uganda; fertilizers (organic) should be introduced in the study area to fertilize the uplands that have reportedly become infertile in order to reduce the pressure the local community members are exerting on the wetlands for agriculture; wetlands management institutions should be empowered financially and political interference in activities aimed at conservation of wetlands in Uganda must cease. There should be uniform implementation of the rules and regulations stipulated in the acts and policies for all members of the public concerning wetlands protection. Lastly, essential community based conservation principles, as stated above, need to be applied carefully and adhered to if effective implementation of community-based conservation of wetlands is to be achieved in Uganda.
- Full Text:
- 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
The state of constitutionalism in Uganda: 1962-2018
- Authors: Bashasha, Turyatemba Alex
- Date: 2018
- Subjects: Constitutional history -- Uganda , Constitutional history Constitutional law -- Uganda
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23669 , vital:30596
- Description: This Thesis examines the state of constitutionalism in Uganda between 1962 and 2018. The central question which it seeks to answer is: ‘why did Ugandan governments persistently fail to adhere to the basic requirements of the doctrine of constitutionalism between 1962 and 2018?’ In answering this question, which has challenged and continues to challenge many academicians, politicians, government officials, researchers and the international community alike, the Thesis adopts the Theory of Neo-patrimonialism as a theoretical lens through which the behaviours of the post-independence presidents of Uganda are examined. The Thesis discovers that, indeed, Neo-patrimonialism is a fundamental framework for analysing and explaining constitutionalism in post-independence Uganda. Against this backdrop, the Thesis concludes that, the collective behaviours of Uganda’s post-independence presidents viewed through the lens of neo-patrimonialism are more fundamental in understanding the failure of democracy and good governance in Uganda than the country’s structural problems of constitutionalism. The originality of the Thesis is in: (a) its being the first comprehensive investigation into why Ugandan governments have persistently failed to adhere to the basic requirements of the doctrine of constitutionalism for the entire period of 56 years (1962-2018) of post-independence Uganda; and (b) its being the first study to apply the Theory of Neo-patrimonialism in explaining the volatile nature and state of constitutionalism in Uganda. The contribution of the Thesis to the existing knowledge lies in its; (a) generation of detailed and well-researched information about the volatility of constitutionalism in Uganda between 1962 and 2018, (b) recommendation of strategies that should be adopted to effectively enhance consititutionalism in Uganda, and (c) authentication of the validity of the claims that despite its shortcomings, Neo-patrimonialism is a Theory which not only continues to define and drive African politics but its application can suitably be used to explain the volatile nature of constitutionalism in post-independence Uganda and the rest of Africa.
- Full Text:
- 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.
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- Date Issued: 2018
Using ambient noise tomography to image the Eastern Cape-Karoo and Karoo regions, South Africa
- Authors: Bezuidenhout, Lucian John-Ross
- Date: 2018
- Subjects: Geometric tomography -- South Africa , Geobiology Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23602 , vital:30585
- Description: The primary aim of this thesis was to explore the use of ambient seismic noise as a tool to map the subsurface of the Cape-Karoo and Karoo region of South Africa. The Karoo is an ideal laboratory to use ambient seismic signal to map the shallow subsurface, as it is a quiet and pristine environment with a relatively well known geology. Ambient seismic signals were continuously recorded at three independent networks (ArrayA, ArrayB and ArrayC). ArrayA and ArrayB comprised 17 temporary stand-alone seismic stations each and recorded ambient noise wavefields for a ten week period between August and October 2015. ArrayC comprised 19 temporary stand-alone seismic stations, recording ambient seismic noise for a period of six weeks between June and July 2016. ArrayA and ArrayB were installed in the south-eastern Cape-Karoo region, near the town of Jansenville and ArrayC was installed near the Cradock-Tarkastad region of South Africa. This thesis is made up of two separate studies. Firstly, the retrieval and coherency of Rayleigh surface waves extracted from the vertical component recordings. For the first time in the south-eastern Cape-Karoo and Karoo area, estimates of Green’s function from cross-correlating ambient noise data between stations pairs were reconstructed and shown, which can be successfully used to image the subsurface. The stacked cross-correlations between all station pairs show clear arrivals of the Rayleigh surface waves. The group velocities of the Rayleigh waves in the 2 to 7 seconds period range were picked and inverted to compute the 2-D group velocity maps. For ArrayA and ArrayB, the resulting 2-D group velocity maps at different periods resulted in a group velocity model from approximately 2 to 7 km depth, which generally show a high velocity anomaly in the north of the study area, most likely imaging the denser, thick sedimentary basin of the Karoo (Carboniferous-Permian). To the south, the low velocity anomaly likely corresponds to the overlying Jurassic- Cretaceous sequences of the younger Algoa Basin (Uitenhage Group). For ArrayC, the group velocity maps showed high velocity regions, which is consistent with the dolerite sill intrusions in the Karoo and the low velocity structures, which was interpreted as the Karoo sediments. Secondly, the study comprised of characterizing the ambient seismic noise source. The first order analysis of the symmetry of the cross-correlation function showed that, although the ambient noise sources are relatively homogeneously distributed in the study area, most (energetic) of the ambient seismic noise propagates from the coast of South Africa. This was verified by analyzing the azimuthal distribution of the ambient seismic noise.
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- Date Issued: 2018
The Moravian church music heritage in South Africa: a historical account and a theoretical framework for the establishment of a music foundation based on the North American concept
- Authors: Boonzaaier, Devandre
- Date: 2018
- Subjects: Church music , Moravian Church -- South Africa Choirs (Music) -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23570 , vital:30581
- Description: This study serves as a contribution to the literature on the music of the Moravian Church with specific reference to the South African Moravian music heritage. The Moravian Church music heritage is documented through the lens of Coloured composers of Moravian church music. In my study, I highlight the origins of the Moravian Church and its underlying philosophies by focusing on important figures and treasures of the Moravian Church. I provide a brief outline of the Moravians’ contribution to education and music. In the study I discuss the importance of record-keeping and rich hymnody of the Moravian church. I also discuss the doctrine, worship and sacraments of the Moravian Church. The literature study provides the history of the music of the American Moravian Church. This serves as a basis for comparison with the Moravian Church music tradition in South Africa, which is discussed in chapter four of this study. Furthermore, I provide an account of the history of the Moravian Church in South Africa. I use the qualitative research method of case studies to detail the music departments of a selected number of congregations within the Moravian Church of South Africa. Chapter five contains biographies of South African Moravian composers. This research adds to the body of new knowledge through the provision of a comprehensive list of South African Moravian composers and provides the first annotated bibliography of their works. Finally, my study concludes with the provision of a theoretical framework for the establishment of a Moravian Music Foundation based on the North American Moravian Music Foundation model.
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- Date Issued: 2018
Synthesis, characterization and application of novel acetals derived from Eucalyptus oil
- Authors: Burger, Kirstin.
- Date: 2018
- Subjects: Plasticizers , Eucalyptus citriodora
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23548 , vital:30579
- Description: The aim of the project was to develop new bio-plasticizer compounds which could be incorporated into infant plastics. Plasticizers increase flexibility of plastic. These plasticizer compounds were derived from crude natural oils such as Eucalyptus citriodora oil and virgin coconut oil. A reagent which could be synthesized from Eucalyptus citriodora oil was, para-menthane-3,8-diol (PMD) which was present in a 60:40 ratio of cis and trans isomers of the diol. A green procedure to synthesize the diol, where an environmentally friendly catalyst, citric acid was used. Optimal conditions were 7% aqueous citric acid as the catalyst and 12 hour reaction which resulted in a citronellal conversion of 88.4 ± 0.80% and PMD selectivity of 75.4 ± 1.22%. As the diol was present in isomers, it was of interest to separate the cis and trans isomers for characterization purposes and later for subsequent individual isomer acetalization reactions. Yields obtained for the reaction for cis and trans-PMD were 51% and 36%, respectively. The kinetics for PMD synthesis from Eucalyptus citriodora oil was determined as second order with a rate constant of 0.0008hr-1 and Ea of 15.77kJ/mol. The isomers of para-menthane-3,8-diol could be separated from the isomeric mixture by solvent extraction at -78°C with n-heptane. Individual rod-shaped crystals could be isolated with this procedure and was characterized by X-ray crystallography techniques and identified as cis-para-menthane-3,8-diol. The trans-para-menthane-3,8-diol was successfully separated, however adequate crystals were not grown for X-ray crystallography analysis. Another method of isomer separation was investigated for PMD by the formation of a complex where anhydrous copper chloride could only form a novel complex with cis-para-menthane-3,8-diol. The trans isomer remained unreacted in the filtrate. The cis-para-menthane-3,8-diol isomer could be freed from the complex to yield pure cis isomer. Aldehydes could be synthesized from virgin coconut oil with carboxylic acid extraction procedures of the crude oil. Subsequent synthesis reactions from carboxylic acid to form aldehydes were performed and octanal (85% yield), decanal (88% yield), dodecanal (86% yield) and tetradecanal (14% yield) could be successfully synthesized as precursors to the novel acetalization reactions. Eight novel cyclic acetals with a characteristic 1,3-dioxine ring were successfully synthesized. However, diastereoisomers of cis-acetal and trans-acetal were present and required separation for characterization 1H-NMR, 13C-NMR, FT-IR, GC-MS and optical rotation techniques. The eight novel acetals were further characterized according to their physical properties such as there was no data available for these compounds. The following properties were determined: molecular mass, molecular formula, density, viscosity, boiling point, refractive index, enthalpy of vaporization, flash point, UV-VIS compatibility, solubility’s, colour and odour determination. Yields of up to 97% were obtained for these acetal compounds. The synthesis of acetals was optimized with batch reactions and optimum conditions were determined where eight catalysts were screened. These catalysts included: scandium triflate, Zeolite, sulphuric acid, p-toluene-sulfonic acid, Amberlyst 15®, Amberlyst 36®, Amberlite® IRA-120 and formic acid. Optimal conditions were with Amberlyst 15® catalyst, 50 minute reaction time at 65°C reaction temperature. The kinetics of the reaction was determined as zero order with a rate constant of 11.92 hr-1 and Ea of 0.050 kJ/mol. The acetalization reaction was evaluated using a UniQsis FlowSyn continuous flow reactor. One of the eight acetals (hexanal acetal) was used for the optimization study and the remaining acetals were evaluated with the optimum flow conditions. The reaction was improved with the use of continuous flow chemistry techniques by lowering of the optimum batch conditions. Various residence times (3.46-17.30 minutes) and temperature range (25-85°C) were studied to obtain optimum conditions. This process was efficient and low maintenance, which produced high acetal product selectivity of Optimum continuous flow conditions were determined at 55°C and 17.30 minute residence time with the flow rate of 0.1 ml/min. Heterogeneous catalysts such as Amberlyst 15® and Zeolite were screened and Amberlyst 15® determined as most favourable. The effect of Amberlyst 15® catalyst loading (0.5-2 g) was investigated over a temperature range of 25-85°C. Optimum catalyst loading was determined at 1g. The 8 compounds were tested for potential as plasticizers. This included mechanical, thermal, migratory and aesthetic testing. The novel acetals had to be compared to known plasticizers. Therefore, their plasticizer properties were compared to two commercial plasticizers: DBP and Eastman 168. As the compounds were derived from natural resources, they would be classified as bio-plasticizers if they exhibited such properties. Therefore, it was of interest to compare the novel compounds to a known bio-plasticizer: PMD-citronellal acetal. This compound was also present as a diastereoisomers mixture of cis and trans isomers. Therefore, diastereoisomers of the 8 acetals were separated as cis and trans isomers in high yields for plasticizer testing purposes. All 11 compounds (8 novel acetals, PMD-citronellal acetal, DBP and Eastman 168) were formulated in PVC to produce plastic films. As previously stated, isomers were present for the acetal compounds and these individual isomers were formulated into PVC formulations to evaluate if there was an effect of stereochemistry in the plastic films. Studies on this phenomenon were limited and therefore of interest. For isomeric plasticizer testing, 9 acetals (8 novel acetals and PMD-citronellal acetal) were used in the testing. Therefore 18 test compounds were formulated in PVC films for isomer plasticizer testing. The effect of increasing the compound amount in the PVC formulation was investigated in the range of 3-12% (w/w). The following tests were evaluated for all PVC test films: elongation, stress to fracture, glass transition temperature, leaching rate, flexibility, gloss and opacity. To validate the data and observations made, statistical validation models were developed to justify experimental design and trends observed. All novel compounds had plasticizer properties and one acetal compound was concluded as superior to DBP and Eastman 168, within the testing scope of the research. It was observed that higher molecular mass acetal compounds had increased plasticizer properties. Isomers for all acetal compounds were concluded to affect plasticizer properties differently and were highly significant. As the novel acetal compounds could be synthesized from natural crude resources, it was interesting to investigate if the synthesized acetals retained their anti-bacterial properties which the precursor oils possessed. Anti-bacterial testing of isomeric mixtures of C5-C12 acetal was investigated and compared to PMD-citronellal acetal and the two commercial plasticizers: DBP and Eastman 168. As the scope of the research focussed on bio-plasticizers for infant plastic products, test bacterial strains were chosen based on the pathogenic strains which cause diseases in babies. Six strains of bacteria were evaluated. It was of interest to evaluate the potency of the compounds by determining the minimum concentration of the compounds which would be potent enough to inhibit the bacteria. The commercial plasticizers inhibited no bacteria within the scope of the research. The acetals retained their anti-bacterial properties where C12 acetal was superior in 4/6 strains of bacteria and PMD-citronellal acetal was superior in 2/6 strains of bacteria. This research is novel and there are presently no data available on this. It was concluded that 8 new bio-plasticizers were synthesized, optimized and tested, within the scope of this research. These compounds were comparable to industry standards in all tests and possessed anti-bacterial properties which the industrial standards don’t possess.
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- Date Issued: 2018
Productivity and resilience of intertidal resources available to extant human foragers on South Africa’s cape south coast: behavioural implications for early Homo sapiens
- Authors: De Vynck, Jan Carlo
- Date: 2018
- Subjects: Marine invertebrates -- South Africa -- Prehistory , Shellfish -- South Africa -- Prehistory Fishes -- Behavior
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30172 , vital:30854
- Description: Studies of pre-historic lifestyles can be limited by a lack of preserved material and sites and resource misinterpretation is augmented by the vagueness of pre-historic subsistence lifestyles. The present can inform the past and this study‟s ethnoarchaeological approach, through modern analogues, examines productivity, resilience and temporal and spatial size variation of intertidal invertebrates on the Cape‟s south coast. O‟Connell (1995) defined the mutualistic relationship between ethnography and archaeology thus: “Archaeology‟s ultimate aim is understanding past human behaviour by patterns in the form and distribution of objects made or modified by humans in the past and knowledge of human behaviour and its material consequences in the present. The first provides direct evidence of past behaviour; the second, a basis for interpreting that evidence”. Coastal archaeology, specifically the contribution of coastal resources to pre-historic subsistence, has gained increased global interest (Erlandson, 2001; Erlandson and Rick, 2008; Codding et al., 2014). Apart from the high representation of preserved shell in coastal archaeological sites, interest in intertidal resources has also been sparked by their economic value compared to terrestrial resource options. Intertidal resources offer low-risk protein acquisition whereas terrestrial protein can be dangerous to procure. However, in the past intertidal subsistence was thought to offer low caloric yields or unfavourable cost-to-benefit relationships until Meehan (1982) convincingly demonstrated the potential caloric „profit‟ possible from coastal foraging; the Anbarra women of northern Australia were contributing significantly to the overall caloric requirements of those people. In South Africa, two possible evolutionary behavioural hypotheses arose from the addition of intertidal resources to pre-historic diets. As background, it is important to note that the oldest global evidence for shellfish procurement [164 000 years ago (ka)] is found on the Cape‟s south coast (Jerardino and Marean, 2010) and the evidence is enriched by other sites from around 110 ka (Voight, 1973; Thackeray, 1988; Henshilwood et al., 2001; Langejans et al., 2012). Furthermore, this period coincides with the emergence of cognitively modern Homo sapiens as evidenced in xx the palaeoarchives from many sites in the region (d‟Errico et al., 2005; Marean et al., 2007; Wurz, 2008; Henshilwood et al., 2009; Watts, 2010; d‟Errico et al., 2012). These features have greatly enhanced the significance and importance of this area to understanding human evolution. The two hypotheses are centred around the effect that intertidal resources could have had on the emergence of our unique species. The addition of a nutritionally beneficial resource to cognitive development is seen by some (Broadhurst et al., 2002; Parkington, 2010) to have driven this cognitive evolution, where others suggest that resources which are both productive and dependable create pro-social proclivities that drive cognitive development (Whitaker and Byrd, 2014; Marean, 2014) and facilitate the migration of humans (Fa, 2008; Codding et al., 2014). Both hypotheses argue that resources on the Cape‟s coast must have been productive and had to be a frequent addition to diet to underpin brain development. The increased frequency of coastal resource procurement or coastal adaptation is therefore seen as an attribute of, or requisite for our species. This thesis attempts to shed light on the contribution of intertidal resources to prehistoric ‒ especially Middle Stone Age (MSA) – subsistence economy on the Cape‟s south coast and the possible effect thereof on human behavioural evolution. The first aim was to investigate the spatial productivity (once-off patch caloric profitability in numerous patches) of intertidal resources and the environmental and behavioural variables affecting it. The second aim was to investigate the resilience of caloric profitability (numerous harvests in the same patch) of these resources to sustained human predation. Productivity itself cannot affect human temporal social dynamics if the resource is swiftly depleted within a specific patch after one or a few harvests. Archaeological records that show the body size of shellfish decreasing over time are usually interpreted to indicate intensive exploitation and the depletion of these resources, but there may be other explanations for such patterns. Therefore, the third aim was to compare temporal and spatial variations in the body size of Turbo sarmaticus in the MSA, Later Stone Age (LSA) and the present day, in order to investigate whether such variations result from human exploitation or environmental changes.
- Full Text:
- 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
The effects of frost on Albany subtropical thicket and nama-karoo shrubland in South Africa
- Authors: Duker, Robert
- Date: 2018
- Subjects: Shrubland ecology , Desert ecology -- South Africa Ecological surveys -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/29951 , vital:30799
- Description: Numerous treeless shrublands exist in areas where climates should support tree growth. In South Africa, the predominantly lowland Albany Subtropical Thicket (thicket), and the predominantly upland Nama-Karoo semi-desert shrubland share a boundary that is often abrupt and analogous to a forest-shrubland alpine ‘treeline’. This boundary exists across similar climatic and edaphic conditions, and field observations and leaf-level experiments suggest that certain thicket component species have lower levels of frost tolerance than the Nama-Karoo shrubs. The hypothesis is that the occurrence of sub-zero temperatures and frost dictates the position of this boundary at both the local landscape and broader regional levels. I test this hypothesis by quantifying leaf-level and whole-plant freezing tolerance of thicket and Nama-Karoo shrubland species, in relation to their local- and regional-scale distribution, and by modelling the occurrence of frost in the mountainous areas of the coastal lowlands relation to 1) naturally occurring boundaries between these two vegetation types, and 2) levels of aboveground net primary productivity (NPP) of Portulacaria afra Jacq. (spekboom) cuttings (planted with the aim of restoring livestock-degraded thicket). I found that the observed and modelled occurrence of frost in the local landscape has significant negative influences on the photosynthetic health, survival and growth rates of thicket component species, and that leaf-level freezing tolerance of evergreen thicket and Nama-Karoo shrubland species is strongly related to their broader regional-scale distributional thresholds. These results support the hypothesis that the occurrence of sub-zero temperatures and frost play a major role in determining the local- and regional-scale distribution of thicket and Nama-Karoo shrubland species, via their reliance on frost-defined refugia at a variety of different scales, and that the once-widespread and regionally dominant thicket vegetation contracted into small climatic refugia during the Last Glacial Maximum (LGM). These results also have major implications for landscape- and regional-level planning of livestock-degraded thicket restoration efforts that use planting of spekboom as an ecosystem engineer, and for predicting boundary shifts under the predicted future warming of global climates.
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- Date Issued: 2018
A social media model for public participation in a South African municipality
- Authors: Fashoro, Ifeoluwapo
- Date: 2018
- Subjects: Information technology -- Social aspects -- South Africa , Social media -- South Africa Political participation -- Technological innovations -- South Africa Municipal government -- South Africa -- Citizen participation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/29851 , vital:30786
- Description: Social media have become the preferred method of communication for individuals, organisations and even governments. These technologies have become ingrained in our everyday lives and have changed the way we communicate, collaborate are informed of recent happenings around the world. Social media websites are reported to be the most popular around the world. In the government sphere, social media is purported as a technology that will revolutionise citizen participation, service delivery and government-citizen interactions. Accordingly, governments around the world are steadily implementing social media in a bid to meet citizens’ demand for immediate and constant access to information, as well as increased opportunities to participate in government. Public participation has become an important focus area for government which could be used to effectively engage citizens and foster citizen trust. The United Nation’s E-government survey reports the presence of 125 countries on social media platforms. Despite the increased use of social media by governments, consensus among researchers is that governments need guidance on how to use social media effectively to achieve the potential benefits proposed by these technologies. Many social media adoptions by governments have been deemed as experimental; no formal action plan was designed, and many government employees are expected to learn social media use on-the-job. The aim of this research was to investigate and propose a social media model for public participation to leverage the opportunities provided by social media and present an effective and structured approach towards public participation. The research was designed as a mixed methods research using a case study based in the Eastern Cape Province of South Africa. The research involved a survey of citizens in the selected municipality based on the Uses and Gratifications Theory, interviews with employees responsible for social media in said municipality and a contents analysis of the existing social media pages of the municipality. The model was developed from the findings of the survey, interviews and existing literature. The implementation of the model was done in the Nelson Mandela Bay Municipality. The municipality appointed a social media champion responsible for obtaining support from top management and politicians within the municipality. Additional staff were added to the social media team and formal social media training was provided to the team. An official social media strategy was drafted and at the time of writing, needed to be approved by top management. The proposed model was operationalised within the Nelson Mandela Bay Municipality. This research makes several contributions to the E-government and social media fields in South Africa. The major contribution is the provision of guidance for South African municipalities to implement and use social media in an effective manner to achieve public participation. The research provided a phased approach to social media implementation that eliminates ad hoc experimentation and ensures the municipality’s social media activities are effective. The development of the model was based on the characteristics of the municipality and its citizens derived from the interviews and survey carried out. There are five phases in the model; Initialisation, Setup, Organisation, Institutionalisation and Maintenance. The model can be thought of as a guideline, and as such municipalities should adapt the implementation of the model to fit their organisational characteristics. The social media model will assist municipalities to determine the resources, tools and tactics to enable them to implement social media effectively, which will result in an improved engagement and participation process with citizens, and thereby foster trust.
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- Date Issued: 2018
Sustainable competitive tourism in South Africa
- Authors: Ferreira, Daniel Petrus
- Date: 2018
- Subjects: Tourism -- South Africa , Sustainable development Competition -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/22464 , vital:29972
- Description: Tourism is one of the major economic industries in the world and is one of the main income sources for many developing countries such as South Africa (SA). The South African tourism industry contributes approximately R309 billion to the country‘s Gross Domestic Product, and is considered the country‘s fastest growing industry. Although, in comparison to 2016 SA experienced a 2% growth rate of international tourist arrivals in 2014, the increase is considerably lower than the global average of 7%. In 2018, SA also dropped five rankings to number 61, as compared to the previous year according to the Global Competitiveness 2017 to 2018 report. Consequently, SA is not considered a competitive global tourism economy. To increase the country‘s position in the global ranking, it must develop policies and marketing strategies that include both competitive and sustainable aspects. The primary objective of this study is to develop a sustainable- and competitive tourism model for SA. The study investigated and analysed how the independent variables (tourism driving forces) influence sustainable- and competitive tourism (dependent variables). From a comprehensive literature review, a hypothetical model was developed to determine tourism driving forces that might influence sustainable- and competitive tourism. Twenty-two hypotheses were formulated to test the relationships between the eleven tourism driving forces and two dependent variables, namely sustainable- and competitive tourism. This quantitative research approach study sought the perceptions of various tourism stakeholders in SA. A survey was conducted with the aid of a structured web-based questionnaire, distributed via e-mail, and posted on various tourism-specific Facebook pages. A combination of convenience- and snowball sampling was utilised. A final sample of 512 respondents was obtained. The items in the questionnaire were validated by conducting exploratory factor analysis, thereafter the Cronbach‘s alpha values were calculated for each of the valid constructs to confirm inter-item reliability. The results of the Pearson product-moment correlation tests between the various independent and dependent variables revealed mostly moderate to strong correlations. For this reason, multi-collinearity diagnostics testing was conducted prior to multiple regression analysis to confirm that there is no evidence of collinearity between the tourism driving forces, as well as between the dependent variables. The multiple regression analysis reveals three statistically significant relationships between the enabling country conditions (market conditions, technological conditions and tourism policy development) and sustainable tourism. In addition, four statistically significant relationships were found between the destination appeal forces (enablers, enhancers, infrastructure and political conditions) and competitive tourism. The empirical findings further confirmed natural attraction promotional tactics as a destination appeal driving force had a statistically significant relationship with both competitive tourism and sustainability tourism. The inter-relationship between sustainable- and competitive tourism was also confirmed, however, competitive tourism was shown to influence sustainable tourism to a larger extent. Multivariate analysis of variance calculations was used to identify whether the demographic profiles of respondents (classification data) occupy a role in how they view the tourism forces (destination appeal and enabling country conditions) important to create tourism demand in South Africa. A total of 69 statistically significant relationships were found between the classification data and the tourism forces. Post-hoc Tukey tests identified numerous significant means differences within the different classification data categories. The Cohen‘s D analysis revealed 135 practically significant relationships, of which twenty had large practical significance. The five key aspects relevant to increase tourism demand were to have a discrimination-free country regarding race, religion and sexual preference, as well as a safe and stable tourism environment without xenophobic violence. For this reason, the SA government must work actively towards providing a peaceful, safe and discrimination-free tourism environment to attract tourists. Based on the multiple regression results, the marketing of SA‘s natural attractions as a destination appeal factor is essential for competitive tourism to enhance the tourism experience, while it is also imperative for sustainable tourism to increase tourism demand. It is thus suggested that SA Tourism update relevant information regarding the country‘s wildlife and national parks monthly to remain competitive in its quest to towards sustainability. As the destination appeal factors (enablers, enhancers, infrastructure and political conditions) had statistically significant relationships with competitive tourism, these destination appeal factors require consideration. It is therefore recommended that SA should ensure its visa regulations are easily understood, and consider introducing a Tourist Visa On Arrival system to increase the country‘s global tourism competitiveness. In addition, SA should consider creating business- and paleo-tourism niche markets for tourism sustainability. Furthermore, the marketing material must outline the favourable infrastructure available and contain visuals to capture the tourists‘ experiences when selecting SA as a travel destination. The SA government should act responsibly in addressing politically-related unrest through public condemnation of xenophobic violence and showing the severe consequences to those involved in it. Based on the empirical results, enabling country condition factors such as market- and technological conditions, as well as paying attention to the development of the tourism policy, are essential in striving towards sustainable tourism in SA. It is thus suggested that tourism companies promote SA‘s current (2018) favourable exchange rate to potential foreign tourists originating from developed countries. Furthermore, the SA government should adopt globally acceptable online travel application technology to provide travellers with access to reliable and accurate information and enable easy and swift online bookings. This study can be considered one of the first in SA to compile a comprehensive model to confirm empirically which tourism driving forces bring about sustainable- and competitive tourism in the country. This model can now be used by other researchers as a framework for further testing within their respective countries. The study is also the first to identify the major role the demographic profiles of tourists can play in how they view the tourism forces by clearly indicating the differences in thinking of the different demographic groups. The recommendations are tailored for different stakeholder groups such as the government, SA Tourism and travel companies to market SA aptly in their quest towards increasing the country‘s tourism competitiveness and striving towards sustainable tourism.
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- Date Issued: 2018