Innovation: its impact on the success of construction micro, small, and medium enterprises in northern Nigeria
- Authors: Tsado, Abel John
- Date: 2019
- Subjects: Construction industry -- Nigeria , Business enterprises -- Nigeria Success in business -- Nigeria Economics—Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44951 , vital:38191
- Description: There is growing recognition of the important role Construction Micro, Small and Medium Enterprises (CMSMEs) play in economic development. In 2013, Nigeria had about 36,994,578 Micro, Small, and Medium Enterprises (MSMEs) and 731,303 CMSMEs, about 1.99% of the total number of MSMEs in the country. However, 50% of CMSMEs in Nigeria close down within their first five years of existence. Consequently, only about 10% of CMSMEs in Nigeria survive, thrive, and grow to maturity. Enterprises failing within so short a time, portend a huge problem surrounding CMSME innovation and success. While literature seems to indicate innovation as the likely way out of CMSMEs failure, few researchers have considered the connection between CMSMEs innovation and their success. Hence, this research aimed to explore the effect of innovation(s) and innovation systems on the success of the Northern Nigerian CMSMEs. The research objectives were: to identify the types of innovation that are predominant in/peculiar to the Northern Nigerian CMSMEs; to determine how the types of innovation impact the success of the Northern Nigerian CMSMEs; to establish what the innovation systems that manage the innovation of the Northern Nigerian CMSMEs are; and, to determine how the innovation systems, promote innovation among the Northern Nigerian CMSMEs. Qualitative research method was utilised; consisting of 17 recorded interviews within Northern Nigerian which is the study area. The interview also employed structured interview guide, comprising structured open-ended questions to ensure consistency and rigour in the data collection process. The research adopted two stage non-probabilistic sampling, comprising judgmental and snowballing sampling for stage one and two respectively. In stage one, participants were drawn judgmentally based on their innovation and in stage two, the sample size was expanded, using a snowballing sampling technique where the participants in stage one suggested other participants who had also been innovative. Data collected were transcribed and open coded, while the codes for innovation types, and innovation impact on CMSME success were developed with the aid of a deductive code earlier developed from literature. The code occurrences were determined and categorised, and themes were developed. These themes were then subjected to interpretation and analysis. The research findings indicate that the predominant type of innovations within the CMSMEs in the northern part of Nigeria are product innovation, management innovation and service innovation. In addition, there are, technological application innovations, logistics innovations and labour innovations. These innovations impact on the profit, capital, customers, workers and the products of the CMSMEs studied. The innovations are responsible for the CMSMEs success periods, reasons for success and their salient points of success. Therefore, the research concludes that innovation impacts on the studied CMSMEs success. Consequently, the research achieved its aim. The study also discovered an absence of systems that support the innovation of CMSMEs in the northern part of Nigeria. Through this research, an innovation system framework has been developed and it is recommended that it be implemented because of the observed lack of innovation systems in Nigeria.
- Full Text:
- Date Issued: 2019
- Authors: Tsado, Abel John
- Date: 2019
- Subjects: Construction industry -- Nigeria , Business enterprises -- Nigeria Success in business -- Nigeria Economics—Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44951 , vital:38191
- Description: There is growing recognition of the important role Construction Micro, Small and Medium Enterprises (CMSMEs) play in economic development. In 2013, Nigeria had about 36,994,578 Micro, Small, and Medium Enterprises (MSMEs) and 731,303 CMSMEs, about 1.99% of the total number of MSMEs in the country. However, 50% of CMSMEs in Nigeria close down within their first five years of existence. Consequently, only about 10% of CMSMEs in Nigeria survive, thrive, and grow to maturity. Enterprises failing within so short a time, portend a huge problem surrounding CMSME innovation and success. While literature seems to indicate innovation as the likely way out of CMSMEs failure, few researchers have considered the connection between CMSMEs innovation and their success. Hence, this research aimed to explore the effect of innovation(s) and innovation systems on the success of the Northern Nigerian CMSMEs. The research objectives were: to identify the types of innovation that are predominant in/peculiar to the Northern Nigerian CMSMEs; to determine how the types of innovation impact the success of the Northern Nigerian CMSMEs; to establish what the innovation systems that manage the innovation of the Northern Nigerian CMSMEs are; and, to determine how the innovation systems, promote innovation among the Northern Nigerian CMSMEs. Qualitative research method was utilised; consisting of 17 recorded interviews within Northern Nigerian which is the study area. The interview also employed structured interview guide, comprising structured open-ended questions to ensure consistency and rigour in the data collection process. The research adopted two stage non-probabilistic sampling, comprising judgmental and snowballing sampling for stage one and two respectively. In stage one, participants were drawn judgmentally based on their innovation and in stage two, the sample size was expanded, using a snowballing sampling technique where the participants in stage one suggested other participants who had also been innovative. Data collected were transcribed and open coded, while the codes for innovation types, and innovation impact on CMSME success were developed with the aid of a deductive code earlier developed from literature. The code occurrences were determined and categorised, and themes were developed. These themes were then subjected to interpretation and analysis. The research findings indicate that the predominant type of innovations within the CMSMEs in the northern part of Nigeria are product innovation, management innovation and service innovation. In addition, there are, technological application innovations, logistics innovations and labour innovations. These innovations impact on the profit, capital, customers, workers and the products of the CMSMEs studied. The innovations are responsible for the CMSMEs success periods, reasons for success and their salient points of success. Therefore, the research concludes that innovation impacts on the studied CMSMEs success. Consequently, the research achieved its aim. The study also discovered an absence of systems that support the innovation of CMSMEs in the northern part of Nigeria. Through this research, an innovation system framework has been developed and it is recommended that it be implemented because of the observed lack of innovation systems in Nigeria.
- Full Text:
- Date Issued: 2019
Integrating sustainability dimensions into construction labour productivity determinants in Zimbabwe
- Authors: Moyo, Tirivavi
- Date: 2020
- Subjects: Construction industry -- Labor productivity -- Zimbabwe , Construction workers -- Zimbabwe Construction industry -- Employees -- Zimbabwe Construction industry -- Management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46207 , vital:39514
- Description: Low construction labour productivity and inadequate welfare of construction workers is a compound challenge in Zimbabwe. This challenge is due to shortcomings situated in the Decent Work Agenda. Whilst a plethora of contributory factors exists, those that affect the Zimbabwean construction industry were identified for interrogation. Therefore, the study aimed to improve and sustain construction labour productivity in Zimbabwe through fulfilling significant decent work substantive elements, in consideration of demographic variables of stakeholders. A cross-sectional survey research strategy was utilised with quantitative data being collected from selected respondents through the use of questionnaires. The population for the study consisted of randomly selected construction companies registered with the Construction Industry Federation of Zimbabwe and based in Harare, Bulawayo and Shurugwi where site managers’/project managers’ participated. Construction skilled and semi-skilled workers on thirteen (13) construction sites, situated within the same study area, participated in the study. Educators from technical and vocational training institutions and respondents from relevant regulatory bodies were also selected to participate in the study. Quantitative data analysis methods which included Pearson chi-squared tests, Mann-Whitney U tests; Kruskal-Wallis tests, Pearson bivariate correlation method and Regression analysis were utilised. Demographic variables (age, gender, designation, educational levels and experience) were utilised to determine the existence of statistically significant differences in respondents’ perceptions. Construction companies are encouraged to implement corporate social responsibility strategies through equipping workers of different educational levels with knowledge and skills that can be transferred to and benefit themselves and their communities. Adequately trained construction workers best serve their communities through improving their livelihoods, improved safety and health consciousness and quality workmanship. People centred management aspects were found to be fundamental within construction sites as they promote the welfare of workers and should precede any productivity improvement drives. Technical and vocational training institutions need to inculcate sustainability learning objectives within their curricula if any meaning strides in enhancing welfare and productivity of workers is to be achieved. Also, establishing structured on-the-job training that incorporates sustainability learning objectives to achieve workers’ safety on sites is essential. There was a consensus that working conditions must ensure the welfare of workers first before any productivity gains can be realised. Provision of acceptable decent working conditions for different designations and educational levels was encouraged. A comprehensive model was developed for sustaining construction labour productivity that included statistically significant regression models and derived statistically significant demographics from construction labour productivity determinants under study. Validation of the regression models was undertaken through cross-validation and comparison with existing theory. Tenable labour productivity performance measurement and reporting must be inclusive of decent work accomplishments. Short-term interventions that include awareness campaigns and provision of adequate working conditions are required for project-based resolutions whilst, long-term interventions are required where structural reforms within the training of skilled, semi-skilled workers and managers are required, for continuous improvement.
- Full Text:
- Date Issued: 2020
Integrating sustainability dimensions into construction labour productivity determinants in Zimbabwe
- Authors: Moyo, Tirivavi
- Date: 2020
- Subjects: Construction industry -- Labor productivity -- Zimbabwe , Construction workers -- Zimbabwe Construction industry -- Employees -- Zimbabwe Construction industry -- Management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46207 , vital:39514
- Description: Low construction labour productivity and inadequate welfare of construction workers is a compound challenge in Zimbabwe. This challenge is due to shortcomings situated in the Decent Work Agenda. Whilst a plethora of contributory factors exists, those that affect the Zimbabwean construction industry were identified for interrogation. Therefore, the study aimed to improve and sustain construction labour productivity in Zimbabwe through fulfilling significant decent work substantive elements, in consideration of demographic variables of stakeholders. A cross-sectional survey research strategy was utilised with quantitative data being collected from selected respondents through the use of questionnaires. The population for the study consisted of randomly selected construction companies registered with the Construction Industry Federation of Zimbabwe and based in Harare, Bulawayo and Shurugwi where site managers’/project managers’ participated. Construction skilled and semi-skilled workers on thirteen (13) construction sites, situated within the same study area, participated in the study. Educators from technical and vocational training institutions and respondents from relevant regulatory bodies were also selected to participate in the study. Quantitative data analysis methods which included Pearson chi-squared tests, Mann-Whitney U tests; Kruskal-Wallis tests, Pearson bivariate correlation method and Regression analysis were utilised. Demographic variables (age, gender, designation, educational levels and experience) were utilised to determine the existence of statistically significant differences in respondents’ perceptions. Construction companies are encouraged to implement corporate social responsibility strategies through equipping workers of different educational levels with knowledge and skills that can be transferred to and benefit themselves and their communities. Adequately trained construction workers best serve their communities through improving their livelihoods, improved safety and health consciousness and quality workmanship. People centred management aspects were found to be fundamental within construction sites as they promote the welfare of workers and should precede any productivity improvement drives. Technical and vocational training institutions need to inculcate sustainability learning objectives within their curricula if any meaning strides in enhancing welfare and productivity of workers is to be achieved. Also, establishing structured on-the-job training that incorporates sustainability learning objectives to achieve workers’ safety on sites is essential. There was a consensus that working conditions must ensure the welfare of workers first before any productivity gains can be realised. Provision of acceptable decent working conditions for different designations and educational levels was encouraged. A comprehensive model was developed for sustaining construction labour productivity that included statistically significant regression models and derived statistically significant demographics from construction labour productivity determinants under study. Validation of the regression models was undertaken through cross-validation and comparison with existing theory. Tenable labour productivity performance measurement and reporting must be inclusive of decent work accomplishments. Short-term interventions that include awareness campaigns and provision of adequate working conditions are required for project-based resolutions whilst, long-term interventions are required where structural reforms within the training of skilled, semi-skilled workers and managers are required, for continuous improvement.
- Full Text:
- Date Issued: 2020
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
- 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
- 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
- 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.
- Full Text:
- Date Issued: 2018
- 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.
- 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.
- Full Text:
- Date Issued: 2018
- 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.
- Full Text:
- Date Issued: 2018
Management capacity within small and medium tourism enterprises (SMTEs)
- Authors: Mxunyelwa, Siyabonga
- Date: 2019
- Subjects: Small business -- South Africa -- Eastern Cape -- Management , Tourism -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/41708 , vital:36574
- Description: The small to medium tourism enterprises are identified as important contributors to the growth of the local and regional economies and creates much needed entrepreneurial ventures. Universally, small to medium tourism enterprises play a significant role in the tourism sector. The small businesses are in many instances deemed to facing risk to economic environmental challenges and face uphill battles to operate their enterprises in a sustainable manner. Management of these enterprises by owners and managers seems to face challenges. This study focuses on small to medium tourism enterprises in the Eastern Cape Province, South Africa, which faces the triple threat challenges of poverty, inequality and unemployment, and is one of the economically poorest provinces of South Africa. In an endeavour to create a trajectory for progression and development of small to medium tourism enterprises, owners and managers are required to undertake management capacity programmes to deal with the problems that confront the enterprise on a daily basis. The study examines the factors impacting on management capacity with specific focus on the small to medium tourism enterprises in the Eastern Cape Province, South Africa. Management capacity is paramount as it builds managerial competency and has become significant to the small business economy, as these enterprises make every effort to avoid discontinuation. Management capacity improves business performance and small enterprises require help in order to have a broader understanding of issues that can be an impediment to address the challenges in the business environment. The factors that could impact on management capacity within the enterprises are the focus of this research. The eleven main factors were identified, namely skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy; and organisational information factors. Furthermore, the study examined the level of influence of these factors on the management capacity of small businesses in the tourism and hospitality sector in the Eastern Cape and investigated the relationships between these factors. A descriptive research design and a quantitative approach were considered suitable for this study. A systematic random sampling technique was utilised to choose a sample of 320 business respondents from the 2012 database of the Eastern Cape Parks and Tourism Agency, comprising of formally registered small tourism businesses. A total of 310 usable questionnaires was finally obtained. In this study descriptive and inferential statistics were applied. Descriptive statistics were captured to highlight the owners and managers’ general characteristics and to consolidate their measurement scores. Utilising inferential statistics, the study undertook an investigation into relationships between demographic variables and business characteristics. Furthermore, an investigation of the relationships amongst the following factors: skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy and organisational information factors was undertaken. Data were subjected to exploratory factor analysis and both the validity and reliability of the research instrument was assessed. The research findings support an overall significant correlation between management capacity and skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy and organisational information. The study also explored the relationship between demographics and business characteristics. A significant relationship was found between business characteristics and variables in the demographic profile, namely the gender of owners/managers, educational levels, qualifications, and gross annual turnover. What follows is a summation of the most significant contributions of this research. The overview of the significance of the tourism sector in the economy and the role of small businesses in the tourism and hospitality industry of the Eastern Cape will benefit researchers and potential owners/managers who have an interest in this developing sector. The study enhances the understanding of the factors that relate to management capacity. The study has established a profile of SMTE sector in the Eastern Cape, South Africa, which can play a significant role for future research. This research makes a contribution to the largely under-researched area of management capacity in small to medium tourism enterprises. Recommendations for owners/managers and consideration of future research included the following. Owners/managers need to have management skills and a strong strategic focus. Through management capacity the needs of the business will be addressed, and capacity building programmes can be tailored to maximise the benefits for owners/managers of SMTEs, thereby improving business performance and avoiding high failure rate. Managers need to be effectively trained to deal with business needs. The management of the business plays a pivotal role in the performance of the enterprise. Managers must be skilled with regards to developing strategic plans, marketing plans, and business plans, thus enhancing management capacity. Longitudinal studies can be undertaken to investigating the same factors which could impact on management capacity. It is recommended that this study be replicated across the global spectrum in order to analyse the factors that impact on management capacity of small to medium tourism businesses of other countries.
- Full Text:
- Date Issued: 2019
- Authors: Mxunyelwa, Siyabonga
- Date: 2019
- Subjects: Small business -- South Africa -- Eastern Cape -- Management , Tourism -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/41708 , vital:36574
- Description: The small to medium tourism enterprises are identified as important contributors to the growth of the local and regional economies and creates much needed entrepreneurial ventures. Universally, small to medium tourism enterprises play a significant role in the tourism sector. The small businesses are in many instances deemed to facing risk to economic environmental challenges and face uphill battles to operate their enterprises in a sustainable manner. Management of these enterprises by owners and managers seems to face challenges. This study focuses on small to medium tourism enterprises in the Eastern Cape Province, South Africa, which faces the triple threat challenges of poverty, inequality and unemployment, and is one of the economically poorest provinces of South Africa. In an endeavour to create a trajectory for progression and development of small to medium tourism enterprises, owners and managers are required to undertake management capacity programmes to deal with the problems that confront the enterprise on a daily basis. The study examines the factors impacting on management capacity with specific focus on the small to medium tourism enterprises in the Eastern Cape Province, South Africa. Management capacity is paramount as it builds managerial competency and has become significant to the small business economy, as these enterprises make every effort to avoid discontinuation. Management capacity improves business performance and small enterprises require help in order to have a broader understanding of issues that can be an impediment to address the challenges in the business environment. The factors that could impact on management capacity within the enterprises are the focus of this research. The eleven main factors were identified, namely skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy; and organisational information factors. Furthermore, the study examined the level of influence of these factors on the management capacity of small businesses in the tourism and hospitality sector in the Eastern Cape and investigated the relationships between these factors. A descriptive research design and a quantitative approach were considered suitable for this study. A systematic random sampling technique was utilised to choose a sample of 320 business respondents from the 2012 database of the Eastern Cape Parks and Tourism Agency, comprising of formally registered small tourism businesses. A total of 310 usable questionnaires was finally obtained. In this study descriptive and inferential statistics were applied. Descriptive statistics were captured to highlight the owners and managers’ general characteristics and to consolidate their measurement scores. Utilising inferential statistics, the study undertook an investigation into relationships between demographic variables and business characteristics. Furthermore, an investigation of the relationships amongst the following factors: skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy and organisational information factors was undertaken. Data were subjected to exploratory factor analysis and both the validity and reliability of the research instrument was assessed. The research findings support an overall significant correlation between management capacity and skills development; reasons for starting a business; business challenges; strategic and management knowledge; business leadership; business resources, business environment; business communication; business organisational leadership; organisational strategy and organisational information. The study also explored the relationship between demographics and business characteristics. A significant relationship was found between business characteristics and variables in the demographic profile, namely the gender of owners/managers, educational levels, qualifications, and gross annual turnover. What follows is a summation of the most significant contributions of this research. The overview of the significance of the tourism sector in the economy and the role of small businesses in the tourism and hospitality industry of the Eastern Cape will benefit researchers and potential owners/managers who have an interest in this developing sector. The study enhances the understanding of the factors that relate to management capacity. The study has established a profile of SMTE sector in the Eastern Cape, South Africa, which can play a significant role for future research. This research makes a contribution to the largely under-researched area of management capacity in small to medium tourism enterprises. Recommendations for owners/managers and consideration of future research included the following. Owners/managers need to have management skills and a strong strategic focus. Through management capacity the needs of the business will be addressed, and capacity building programmes can be tailored to maximise the benefits for owners/managers of SMTEs, thereby improving business performance and avoiding high failure rate. Managers need to be effectively trained to deal with business needs. The management of the business plays a pivotal role in the performance of the enterprise. Managers must be skilled with regards to developing strategic plans, marketing plans, and business plans, thus enhancing management capacity. Longitudinal studies can be undertaken to investigating the same factors which could impact on management capacity. It is recommended that this study be replicated across the global spectrum in order to analyse the factors that impact on management capacity of small to medium tourism businesses of other countries.
- Full Text:
- Date Issued: 2019
Managing the corporate reputation of a transforming organisation: a study of multimedia University of Kenya
- Authors: Mtange, Margaret Mulekani
- Date: 2020
- Subjects: Organizational change -- Management , Universities and colleges -- Kenya -- Sociological aspects -- Case studies , Universities and colleges -- Research -- Economic aspects -- Kenya -- Case studies
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/50837 , vital:42873
- Description: Universities, like other organisations, are challenged to manage corporate identity and reputation to maintain a competitive edge. Few studies in Africa focus on the impact of internal communication on corporate identity and reputation management during organisational transformation. Thus, this study interrogated how a transforming and complex university in Kenya managed the corporate identity, image and reputation for competitive advantage. The purpose of the study was to establish how Multimedia University of Kenya (MMU) management communicated with its employees to nurture the corporate identity, image and reputation during a ten-year period of transformation. The study draws insights from in-depth interviews with 23 university management members, 178 self-administered questionnaires through random stratification of MMU employees, and content review of two MMU strategic plans ranging from 2011 to 2021. The findings suggest that MMU management used formal and interactive channels to create awareness of organisational transformation. These channels included face-to-face engagements, formal meetings and mediated communication through telephone conversations and intranet that facilitated record keeping. The management engaged in top-down and bottom-up communication to build employee trust, while employees expressed reservations of bottom-up information accuracy, suggesting information exclusion. On the contrary, the employees preferred digital and interpersonal channels for internal communication, which included telephone conversations, social media, personal visits by MMU management, and university events. Publicity activities were to disseminate information to prospective students and sponsors through selected private television, vernacular radio, and MMU radio stations, traditional print media, and the MMU website to communicate the MMU brand and image. Employees acknowledged that MMU brands itself as a leader in telecommunication, technology, mechanical, manufacturing, and media training through state-of-the-art equipment, robust faculty, and problem-solving ventures through research. The current study proposes stronger employee involvement, executive packaging and positioning, coaching successful faculty members as brand ambassadors, retraining employees, and employee participation in policy formulation to enhance new culture. In addition, these opositions will enhance the corporate identity, brand, as well as university performance, product quality, policy and processes to enrich the corporate reputation during transformation. The findings challenge university management to actively engage the corporate communication function, emphasise employee participation, and focus on the continual improvement of corporate identity and reputation management practices for competitive advantage. The current study proposes a participative, multi-layered and multi-dimensional communication model for efficient and excellent internal communication. The current study recommends that corporate communication practitioner be strategically positioned to coordinate employee engagement, utilise appropriate communication channels and counsel university management on corporate identity, image and reputation management during organisational transformation.
- Full Text:
- Date Issued: 2020
- Authors: Mtange, Margaret Mulekani
- Date: 2020
- Subjects: Organizational change -- Management , Universities and colleges -- Kenya -- Sociological aspects -- Case studies , Universities and colleges -- Research -- Economic aspects -- Kenya -- Case studies
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/50837 , vital:42873
- Description: Universities, like other organisations, are challenged to manage corporate identity and reputation to maintain a competitive edge. Few studies in Africa focus on the impact of internal communication on corporate identity and reputation management during organisational transformation. Thus, this study interrogated how a transforming and complex university in Kenya managed the corporate identity, image and reputation for competitive advantage. The purpose of the study was to establish how Multimedia University of Kenya (MMU) management communicated with its employees to nurture the corporate identity, image and reputation during a ten-year period of transformation. The study draws insights from in-depth interviews with 23 university management members, 178 self-administered questionnaires through random stratification of MMU employees, and content review of two MMU strategic plans ranging from 2011 to 2021. The findings suggest that MMU management used formal and interactive channels to create awareness of organisational transformation. These channels included face-to-face engagements, formal meetings and mediated communication through telephone conversations and intranet that facilitated record keeping. The management engaged in top-down and bottom-up communication to build employee trust, while employees expressed reservations of bottom-up information accuracy, suggesting information exclusion. On the contrary, the employees preferred digital and interpersonal channels for internal communication, which included telephone conversations, social media, personal visits by MMU management, and university events. Publicity activities were to disseminate information to prospective students and sponsors through selected private television, vernacular radio, and MMU radio stations, traditional print media, and the MMU website to communicate the MMU brand and image. Employees acknowledged that MMU brands itself as a leader in telecommunication, technology, mechanical, manufacturing, and media training through state-of-the-art equipment, robust faculty, and problem-solving ventures through research. The current study proposes stronger employee involvement, executive packaging and positioning, coaching successful faculty members as brand ambassadors, retraining employees, and employee participation in policy formulation to enhance new culture. In addition, these opositions will enhance the corporate identity, brand, as well as university performance, product quality, policy and processes to enrich the corporate reputation during transformation. The findings challenge university management to actively engage the corporate communication function, emphasise employee participation, and focus on the continual improvement of corporate identity and reputation management practices for competitive advantage. The current study proposes a participative, multi-layered and multi-dimensional communication model for efficient and excellent internal communication. The current study recommends that corporate communication practitioner be strategically positioned to coordinate employee engagement, utilise appropriate communication channels and counsel university management on corporate identity, image and reputation management during organisational transformation.
- Full Text:
- Date Issued: 2020
Mechanisms and modes of β-N-methylamino-lalanine neurotoxicity: the basis for designing therapies
- Authors: Van Onselen, Rianita
- Date: 2019
- Subjects: Cyanobacteria , Amino acids -- Toxicology , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32971 , vital:32483
- Description: Since the discovery of the non-canonical amino acid β-N-methylamino-L-alanine (BMAA) and the demonstration of its acute neurotoxicity in chicks and rats, it has been postulated that BMAA might contribute to the development of neurodegenerative diseases worldwide due to its presence in numerous aquatic and terrestrial food webs. This hypothesized link was widely criticized because of the inability to reproduce symptoms in a BMAA-exposed animal model that resembled the symptoms observed in humans, and for the inability to achieve significant levels of toxicity in in vitro models via the postulated mechanisms of toxicity. The most widely described mechanism of BMAA toxicity was excitotoxicity by over-excitation of ionotropic and/or metabotropic glutamate receptors following activation by BMAA. However, the excitotoxic potency of BMAA is much lower than those of other known excitotoxins and it was not known whether BMAA could accumulate in significant concentrations in synapses to cause the said excitotoxicity. Therefore, uptake of BMAA into synaptic vesicles from where it can be released into synapses in high concentrations, was investigated and it was found that, unlike the uptake that was observed for glutamate, BMAA was not taken up into synaptic vesicles. This discovery suggests that BMAA is not released into synapses via synaptic vesicles and that excitotoxicity is an unlikely mechanism of BMAA toxicity in mammalian systems. Misincorporation of BMAA into proteins in the place of L-serine was suggested to be an important mechanism of BMAA toxicity that could lead to protein misfolding and the subsequent protein aggregates that are typically found in the central nervous system (CNS) of neurodegenerative disease patients. However, previous studies in prokaryotes and in a rat pheochromocytoma PC12 cell line showed that misincorporation of BMAA does not occur to any significant extent. However, these studies were criticized for not using human-derived model systems to show that misincorporation does not occur, and it was argued that due to differences in mitochondrial protein synthesis mechanisms, misincorporation of BMAA into human proteins could not be ruled out as a possible mechanism of toxicity. Therefore, misincorporation of BMAA was investigated in a number of human-derived non-neuronal cell lines and directly compared to the misincorporation of other known amino acid analogues. No evidence of misincorporation of BMAA into these cell lines was obtained and therefore it was concluded that misincorporation of BMAA into proteins does not occur in human-derived cell models. Although misincorporation of BMAA into proteins was refuted as a mechanism of toxicity, the strong interactions between BMAA and proteins that require extensive purification procedures to remove the associated BMAA, could not be discounted as a possible contributor to the toxicity of BMAA. Cell-free interactions between BMAA and enzymes, which resulted in reduced activity, were described previously but the nature of these interactions was never determined. Therefore, the direct interactions between BMAA and a range of commercial proteins and melanin (that is known to also have a strong affinity for BMAA) were investigated in an attempt to describe the nature of these interactions. It was discovered that BMAA has a high affinity for hydroxyl groups, and that if these hydroxyl groups in the form of hydroxyl containing amino acid residues occurred in important regulatory or active sites of proteins, BMAA reduced the enzyme activity. Catalase was subsequently selected as an important enzyme required for the maintenance of the delicate reactive oxygen species (ROS) balance in the CNS, to test the effect of BMAA on the activity of the enzyme. BMAA inhibited a human commercial extract of catalase in a cell free system, and this inhibition appeared to be non-competitive in nature. Subsequently, catalase in an extract from a human cell line was also shown to be inhibited by BMAA and it was concluded that this BMAA induced inhibition of catalase could be an important contributor to the toxicity of BMAA in in vivo systems. The affinity of BMAA for hydroxyl groups, especially the reactive L-tyrosine side chain hydroxyl, was recognized as a possible mechanism that can be utilized to protect against the toxicity of BMAA. It was subsequently shown that excess concentrations of L-serine and L-tyrosine could protect against the BMAA-induced enzyme inhibition and improper folding of proteins in a cell-free system. By administering an equimolar concentration of either L-phenylalanine (the soluble precursor of L-tyrosine) or L-serine an hour before administration of BMAA in a rat model, the BMAA-induced neurotoxicity was greatly reduced, especially by treatment with L-phenylalanine, which resulted in a decrease of between 60-70% in the observed neuropathologies. It was recognized that the protection offered by L-phenylalanine was greater than would be expected if protection was by virtue of direct hydroxyl binding alone and it was subsequently hypothesized that the conversion of L-phenylalanine to dopamine could have contributed to the observed protection. Subsequently, the possible protection offered by dopamine, administered as L-DOPA, against BMAA neurotoxicity was investigated in the same neonatal rat model and compared to the protection offered by L-tyrosine. It was discovered that dopamine protected against the BMAAinduced neuronal cell losses in the hippocampus, striatum and spinal cord but it was not as efficient as L-tyrosine in protection against the BMAA-induced proteinopathies, suggesting two distinct mechanisms of BMAA toxicity, one of which is a depletion of dopamine, which had not been previously described. Finally, the nature of the BMAA-induced dopamine depletion was investigated by administering BMAA in combination with other dopaminergic modifiers viz. apomorphine (a D1/D2 receptor agonist), a dopamine transporter inhibitor (GBR12783) and reserpine (a vesicular monoamine transporter -VMAT2- inhibitor) to the neonatal rat model in an attempt to describe how BMAA functions as a dopaminergic toxin. Based on these results it was concluded that BMAA inhibits uptake of dopamine into synaptic vesicles by inhibiting VMAT2-mediated uptake of dopamine, which causes neuronal loss in the hippocampus, striatum and substantia nigra pars compacta, and that the BMAA-induced inhibition of catalase contributes significantly to the toxicity of BMAA by causing an accumulation of hydrogen peroxide in the hippocampus, striatum and spinal cord, which results in extensive neuronal damage in these areas. This work was the first to thoroughly investigate the mechanisms that explain the observed pathologies caused by BMAA in an in vivo model, and was the first to suggest that BMAA can reduce the dopamine in the CNS by inhibiting VMAT2-mediated uptake of dopamine into synaptic vesicles, and increase damage by reactive oxygen species by inhibiting catalase. BMAA is therefore a multimechanistic and multimodal.
- Full Text:
- Date Issued: 2019
- Authors: Van Onselen, Rianita
- Date: 2019
- Subjects: Cyanobacteria , Amino acids -- Toxicology , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32971 , vital:32483
- Description: Since the discovery of the non-canonical amino acid β-N-methylamino-L-alanine (BMAA) and the demonstration of its acute neurotoxicity in chicks and rats, it has been postulated that BMAA might contribute to the development of neurodegenerative diseases worldwide due to its presence in numerous aquatic and terrestrial food webs. This hypothesized link was widely criticized because of the inability to reproduce symptoms in a BMAA-exposed animal model that resembled the symptoms observed in humans, and for the inability to achieve significant levels of toxicity in in vitro models via the postulated mechanisms of toxicity. The most widely described mechanism of BMAA toxicity was excitotoxicity by over-excitation of ionotropic and/or metabotropic glutamate receptors following activation by BMAA. However, the excitotoxic potency of BMAA is much lower than those of other known excitotoxins and it was not known whether BMAA could accumulate in significant concentrations in synapses to cause the said excitotoxicity. Therefore, uptake of BMAA into synaptic vesicles from where it can be released into synapses in high concentrations, was investigated and it was found that, unlike the uptake that was observed for glutamate, BMAA was not taken up into synaptic vesicles. This discovery suggests that BMAA is not released into synapses via synaptic vesicles and that excitotoxicity is an unlikely mechanism of BMAA toxicity in mammalian systems. Misincorporation of BMAA into proteins in the place of L-serine was suggested to be an important mechanism of BMAA toxicity that could lead to protein misfolding and the subsequent protein aggregates that are typically found in the central nervous system (CNS) of neurodegenerative disease patients. However, previous studies in prokaryotes and in a rat pheochromocytoma PC12 cell line showed that misincorporation of BMAA does not occur to any significant extent. However, these studies were criticized for not using human-derived model systems to show that misincorporation does not occur, and it was argued that due to differences in mitochondrial protein synthesis mechanisms, misincorporation of BMAA into human proteins could not be ruled out as a possible mechanism of toxicity. Therefore, misincorporation of BMAA was investigated in a number of human-derived non-neuronal cell lines and directly compared to the misincorporation of other known amino acid analogues. No evidence of misincorporation of BMAA into these cell lines was obtained and therefore it was concluded that misincorporation of BMAA into proteins does not occur in human-derived cell models. Although misincorporation of BMAA into proteins was refuted as a mechanism of toxicity, the strong interactions between BMAA and proteins that require extensive purification procedures to remove the associated BMAA, could not be discounted as a possible contributor to the toxicity of BMAA. Cell-free interactions between BMAA and enzymes, which resulted in reduced activity, were described previously but the nature of these interactions was never determined. Therefore, the direct interactions between BMAA and a range of commercial proteins and melanin (that is known to also have a strong affinity for BMAA) were investigated in an attempt to describe the nature of these interactions. It was discovered that BMAA has a high affinity for hydroxyl groups, and that if these hydroxyl groups in the form of hydroxyl containing amino acid residues occurred in important regulatory or active sites of proteins, BMAA reduced the enzyme activity. Catalase was subsequently selected as an important enzyme required for the maintenance of the delicate reactive oxygen species (ROS) balance in the CNS, to test the effect of BMAA on the activity of the enzyme. BMAA inhibited a human commercial extract of catalase in a cell free system, and this inhibition appeared to be non-competitive in nature. Subsequently, catalase in an extract from a human cell line was also shown to be inhibited by BMAA and it was concluded that this BMAA induced inhibition of catalase could be an important contributor to the toxicity of BMAA in in vivo systems. The affinity of BMAA for hydroxyl groups, especially the reactive L-tyrosine side chain hydroxyl, was recognized as a possible mechanism that can be utilized to protect against the toxicity of BMAA. It was subsequently shown that excess concentrations of L-serine and L-tyrosine could protect against the BMAA-induced enzyme inhibition and improper folding of proteins in a cell-free system. By administering an equimolar concentration of either L-phenylalanine (the soluble precursor of L-tyrosine) or L-serine an hour before administration of BMAA in a rat model, the BMAA-induced neurotoxicity was greatly reduced, especially by treatment with L-phenylalanine, which resulted in a decrease of between 60-70% in the observed neuropathologies. It was recognized that the protection offered by L-phenylalanine was greater than would be expected if protection was by virtue of direct hydroxyl binding alone and it was subsequently hypothesized that the conversion of L-phenylalanine to dopamine could have contributed to the observed protection. Subsequently, the possible protection offered by dopamine, administered as L-DOPA, against BMAA neurotoxicity was investigated in the same neonatal rat model and compared to the protection offered by L-tyrosine. It was discovered that dopamine protected against the BMAAinduced neuronal cell losses in the hippocampus, striatum and spinal cord but it was not as efficient as L-tyrosine in protection against the BMAA-induced proteinopathies, suggesting two distinct mechanisms of BMAA toxicity, one of which is a depletion of dopamine, which had not been previously described. Finally, the nature of the BMAA-induced dopamine depletion was investigated by administering BMAA in combination with other dopaminergic modifiers viz. apomorphine (a D1/D2 receptor agonist), a dopamine transporter inhibitor (GBR12783) and reserpine (a vesicular monoamine transporter -VMAT2- inhibitor) to the neonatal rat model in an attempt to describe how BMAA functions as a dopaminergic toxin. Based on these results it was concluded that BMAA inhibits uptake of dopamine into synaptic vesicles by inhibiting VMAT2-mediated uptake of dopamine, which causes neuronal loss in the hippocampus, striatum and substantia nigra pars compacta, and that the BMAA-induced inhibition of catalase contributes significantly to the toxicity of BMAA by causing an accumulation of hydrogen peroxide in the hippocampus, striatum and spinal cord, which results in extensive neuronal damage in these areas. This work was the first to thoroughly investigate the mechanisms that explain the observed pathologies caused by BMAA in an in vivo model, and was the first to suggest that BMAA can reduce the dopamine in the CNS by inhibiting VMAT2-mediated uptake of dopamine into synaptic vesicles, and increase damage by reactive oxygen species by inhibiting catalase. BMAA is therefore a multimechanistic and multimodal.
- Full Text:
- Date Issued: 2019
Mechatronics based highspeed rotational piezo actuator
- Authors: Raffler, Oliver
- Date: 2020
- Subjects: Piezoelectric materials , Piezoelectric devices Mechatronics
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/${Handle} , vital:39811
- Description: The aim of this thesis is the development of a novel mechatronics-based high speed piezo actuator for rotational and linear motion. Mainly, the thesis deals with the development of a system for mechanical coupling of any number of piezostacks. This mechanical coupling allows the actuator to achieve a significantly increased deflection compared to current approaches. The developed concept offers the possibility of a linear or rotary motion. It is also possible to combine the two types of movement. In the first step, in order to gain a better understanding of the topic, the piezo technology and especially the existing piezo actuators and -motors are examined. Currently, the force generated by the piezo actuators is mainly transmitted by friction. The only exception is the PAD-Actuator, which transmits force by means of form locking. The concept developed here also transmits its force by means of form locking and, in addition to that, offers a novel and unique drive concept in the field of piezo actuators. In the course of this thesis a new concept for the mechanical coupling of piezo actuators was developed, simulated and subsequently manufactured. Thus the system could be examined under real conditions. The investigations carried out mainly dealt with quasi-static and dynamic investigations. In addition to that, the emission of the airborne and structure-borne noise of the system was analysed.
- Full Text:
- Date Issued: 2020
- Authors: Raffler, Oliver
- Date: 2020
- Subjects: Piezoelectric materials , Piezoelectric devices Mechatronics
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/${Handle} , vital:39811
- Description: The aim of this thesis is the development of a novel mechatronics-based high speed piezo actuator for rotational and linear motion. Mainly, the thesis deals with the development of a system for mechanical coupling of any number of piezostacks. This mechanical coupling allows the actuator to achieve a significantly increased deflection compared to current approaches. The developed concept offers the possibility of a linear or rotary motion. It is also possible to combine the two types of movement. In the first step, in order to gain a better understanding of the topic, the piezo technology and especially the existing piezo actuators and -motors are examined. Currently, the force generated by the piezo actuators is mainly transmitted by friction. The only exception is the PAD-Actuator, which transmits force by means of form locking. The concept developed here also transmits its force by means of form locking and, in addition to that, offers a novel and unique drive concept in the field of piezo actuators. In the course of this thesis a new concept for the mechanical coupling of piezo actuators was developed, simulated and subsequently manufactured. Thus the system could be examined under real conditions. The investigations carried out mainly dealt with quasi-static and dynamic investigations. In addition to that, the emission of the airborne and structure-borne noise of the system was analysed.
- Full Text:
- Date Issued: 2020
Microalgae as indicators of environmental change in the St Lucia estuarine system
- Authors: Nunes, Monique
- Date: 2019
- Subjects: Microalgae -- South Africa -- St Lucia estuarine
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/31165 , vital:31333
- Description: The St Lucia system represents 56% of the estuarine habitat area in South Africa. This dynamic estuarine lake responds to a complex interaction of climatic and anthropogenic drivers. There has been a long history of human interventions and the extended drought (2002-2012) led to major changes. In 1952, the inlet shared between the estuarine system and the Mfolozi River was artificially separated, which significantly reduced freshwater inflow. The systems were separated because of the silt load from the expanding agricultural activities in the Mfolozi River catchment. The drought prompted a critical review of re-establishing the historic connection, and in July 2012, the beach spillway was excavated marking the start of restoring connectivity. Increased rainfall coupled with the partial re-connection with the agriculturally-impacted Mfolozi River shifted the St Lucia estuarine system to a new wet phase. This study investigated the microalgal dynamics of the estuarine system as it transitioned to this new wet phase. Results showed that the phytoplankton and microphytobenthos (MPB) biomass was low (< 5 ug l-1 and < 60 mg m-2 respectively) throughout the system due to nutrient and light availability, water residence time and sediment type. The increased freshwater inflow from the Mfolozi River was limited to the Narrows and available nutrients promoted the growth of cyanobacteria and dinophytes in the water column. Of interest was the presence of the potentially harmful algal species Prorocentrum minimum. A weekly study investigated the relationship between freshwater inflow, phytoplankton succession and the introduction and persistence of harmful microalgal species in the lower reaches. The increased freshwater inflow received from the Mfolozi River has led to a system in a constant state of flux. The changes in salinity, light availability and water residence time, shifted the phytoplankton functional group structure to one where chlorophytes and euglenoids were dominant. The persistence of the nutrient tolerant euglenoids highlighted the influence of the nutrient-enriched freshwater inflow on the phytoplankton functional groups. However, the relative abundance of all functional groups remained low due to the rapid change in environmental conditions. The next step was to test the use of an artificial substrate as a monitoring method to detect nutrient induced change. Findings from the 28-day study showed that epilithic diatom communities growing on glass slides were good indicators of nutrient enrichment. The epilithic algal biomass increased significantly from 1.5 mg m-2 (Day 14) to 6 mg m-2 (Day 21), following peak river inflow. In contrast, the phytoplankton and MPB showed no discernible increase in biomass. Epilithic diatom community diversity, richness and evenness scores declined due to the increasing relative abundance of a single nutrient tolerant species, Cocconeis placentula var. euglypta. The use of diatoms as indicators of change depends on the accuracy of identification to species level. This can be a slow process requiring a high level of taxonomic expertise. Considering that molecular phylogenetic methods are readily used to produce a reliable taxonomic list, the suitability of DNA metabarcoding for diatom monitoring in the St Lucia Estuary was tested. Comparisons between the molecular and morphological method indicated that the diatom taxonomic composition was similar at 9 to 27% for genus level and 2 to 9% at species level. The low taxonomic similarity was related to the large number of unclassified DNA representative sequences included in the molecular inventory due to the incomplete DNA library database. However, the available operational taxonomic units (OTUs) from the molecular method did provide an effective alternative to determine the relevant community diversity estimates required for the application of the South African Estuarine Health Index (EHI). This research has highlighted the dynamic nature of the St Lucia estuarine system and the effectiveness of the microalgal communities to differentiate between the cyclical climatic phases and anthropogenic stressors such as nutrient enrichment.
- Full Text:
- Date Issued: 2019
- Authors: Nunes, Monique
- Date: 2019
- Subjects: Microalgae -- South Africa -- St Lucia estuarine
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/31165 , vital:31333
- Description: The St Lucia system represents 56% of the estuarine habitat area in South Africa. This dynamic estuarine lake responds to a complex interaction of climatic and anthropogenic drivers. There has been a long history of human interventions and the extended drought (2002-2012) led to major changes. In 1952, the inlet shared between the estuarine system and the Mfolozi River was artificially separated, which significantly reduced freshwater inflow. The systems were separated because of the silt load from the expanding agricultural activities in the Mfolozi River catchment. The drought prompted a critical review of re-establishing the historic connection, and in July 2012, the beach spillway was excavated marking the start of restoring connectivity. Increased rainfall coupled with the partial re-connection with the agriculturally-impacted Mfolozi River shifted the St Lucia estuarine system to a new wet phase. This study investigated the microalgal dynamics of the estuarine system as it transitioned to this new wet phase. Results showed that the phytoplankton and microphytobenthos (MPB) biomass was low (< 5 ug l-1 and < 60 mg m-2 respectively) throughout the system due to nutrient and light availability, water residence time and sediment type. The increased freshwater inflow from the Mfolozi River was limited to the Narrows and available nutrients promoted the growth of cyanobacteria and dinophytes in the water column. Of interest was the presence of the potentially harmful algal species Prorocentrum minimum. A weekly study investigated the relationship between freshwater inflow, phytoplankton succession and the introduction and persistence of harmful microalgal species in the lower reaches. The increased freshwater inflow received from the Mfolozi River has led to a system in a constant state of flux. The changes in salinity, light availability and water residence time, shifted the phytoplankton functional group structure to one where chlorophytes and euglenoids were dominant. The persistence of the nutrient tolerant euglenoids highlighted the influence of the nutrient-enriched freshwater inflow on the phytoplankton functional groups. However, the relative abundance of all functional groups remained low due to the rapid change in environmental conditions. The next step was to test the use of an artificial substrate as a monitoring method to detect nutrient induced change. Findings from the 28-day study showed that epilithic diatom communities growing on glass slides were good indicators of nutrient enrichment. The epilithic algal biomass increased significantly from 1.5 mg m-2 (Day 14) to 6 mg m-2 (Day 21), following peak river inflow. In contrast, the phytoplankton and MPB showed no discernible increase in biomass. Epilithic diatom community diversity, richness and evenness scores declined due to the increasing relative abundance of a single nutrient tolerant species, Cocconeis placentula var. euglypta. The use of diatoms as indicators of change depends on the accuracy of identification to species level. This can be a slow process requiring a high level of taxonomic expertise. Considering that molecular phylogenetic methods are readily used to produce a reliable taxonomic list, the suitability of DNA metabarcoding for diatom monitoring in the St Lucia Estuary was tested. Comparisons between the molecular and morphological method indicated that the diatom taxonomic composition was similar at 9 to 27% for genus level and 2 to 9% at species level. The low taxonomic similarity was related to the large number of unclassified DNA representative sequences included in the molecular inventory due to the incomplete DNA library database. However, the available operational taxonomic units (OTUs) from the molecular method did provide an effective alternative to determine the relevant community diversity estimates required for the application of the South African Estuarine Health Index (EHI). This research has highlighted the dynamic nature of the St Lucia estuarine system and the effectiveness of the microalgal communities to differentiate between the cyclical climatic phases and anthropogenic stressors such as nutrient enrichment.
- Full Text:
- Date Issued: 2019
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
- 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
Microstructural evolution of welded creep aged 12% cr martensitic stainless steel
- Authors: Marx, Genevéve
- Date: 2019
- Subjects: Stainless steel -- Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30766 , vital:31128
- Description: Tempered martensite ferritic (TMF) steels with 9-12% Cr additions are used extensively for high-pressure steam pipes in coal-fired power plants. They operate at temperatures above 500ºC and are consequently susceptible to creep damage. Due to economic reasons, welding must be performed on service exposed materials when a component needs to be replaced. Fusion welding results in the formation of different microstructural regions within the weldment. The primary failure mechanism of TMF steel welded components is Type IV cracking that results from accelerated void formation in the fine-grained heat affected zone (FGHAZ) during creep. Short-term creep-tests performed across weldments made on new and service exposed steels have shown that the weldment consistently fails in the FGHAZ of the service exposed material. This observation has not yet been fully explained since not much is known about the microstructural evolution of creep aged material during welding. Thus, further investigation on the microstructure of welded creep aged material is warranted. The main aim of this thesis was to investigate the microstructural evolution when welding upon creep aged 9-12% Cr martensitic steels using advanced electron microscopy techniques. X20CrMoV12-1 (12% Cr) in the virgin and long-term service-exposed state were investigated. GleebleTM weld simulation of the FGHAZ was performed on the materials. Detailed microstructural investigations were conducted on the parent and simulated FGHAZ materials to analyse the voids, dislocation density, micro-grains, and precipitates (M23C6, MX, Laves, Z-phase) in the materials. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) was used to examine the voids. Twin-jet electropolished specimens were prepared for precipitate, micro-grain and substructure analyses using Transmission Kikuchi Diffraction (TKD) combined with Energy Dispersive Spectrometry (EDS), Concentric Backscatter (CBS) imaging, Energy-Filtered Transmission Electron Microscopy (EFTEM), and Annular Dark-Field Scanning Transmission Electron Microscopy (ADF-STEM) combined with EDS. The precipitates were extracted from the iron matrix using Bulk Replication and further investigated using EFTEM and STEM-EDS.
- Full Text:
- Date Issued: 2019
- Authors: Marx, Genevéve
- Date: 2019
- Subjects: Stainless steel -- Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30766 , vital:31128
- Description: Tempered martensite ferritic (TMF) steels with 9-12% Cr additions are used extensively for high-pressure steam pipes in coal-fired power plants. They operate at temperatures above 500ºC and are consequently susceptible to creep damage. Due to economic reasons, welding must be performed on service exposed materials when a component needs to be replaced. Fusion welding results in the formation of different microstructural regions within the weldment. The primary failure mechanism of TMF steel welded components is Type IV cracking that results from accelerated void formation in the fine-grained heat affected zone (FGHAZ) during creep. Short-term creep-tests performed across weldments made on new and service exposed steels have shown that the weldment consistently fails in the FGHAZ of the service exposed material. This observation has not yet been fully explained since not much is known about the microstructural evolution of creep aged material during welding. Thus, further investigation on the microstructure of welded creep aged material is warranted. The main aim of this thesis was to investigate the microstructural evolution when welding upon creep aged 9-12% Cr martensitic steels using advanced electron microscopy techniques. X20CrMoV12-1 (12% Cr) in the virgin and long-term service-exposed state were investigated. GleebleTM weld simulation of the FGHAZ was performed on the materials. Detailed microstructural investigations were conducted on the parent and simulated FGHAZ materials to analyse the voids, dislocation density, micro-grains, and precipitates (M23C6, MX, Laves, Z-phase) in the materials. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) was used to examine the voids. Twin-jet electropolished specimens were prepared for precipitate, micro-grain and substructure analyses using Transmission Kikuchi Diffraction (TKD) combined with Energy Dispersive Spectrometry (EDS), Concentric Backscatter (CBS) imaging, Energy-Filtered Transmission Electron Microscopy (EFTEM), and Annular Dark-Field Scanning Transmission Electron Microscopy (ADF-STEM) combined with EDS. The precipitates were extracted from the iron matrix using Bulk Replication and further investigated using EFTEM and STEM-EDS.
- Full Text:
- Date Issued: 2019
Molecularly imprinted polymeric materials for adsorptive removal of nitrogen compounds from fuel oils
- Abdul-Quadir, Muhammad Sabiu
- 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
- 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
- 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.
- Full Text:
- Date Issued: 2018
- 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.
- Full Text:
- Date Issued: 2018
Ocean dynamics of the shelf and bays of the eastern Agulhas bank: a process-oriented numerical modelling study
- Authors: Bailey, Dylan Francis
- Date: 2020
- Subjects: Oceanography -- Research , Marine biology , Marine meteorology , Hydrography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49038 , vital:41595
- Description: There is a general need for a broader base of information on the finer detail of ocean processes in the Eastern Agulhas Bank region. In this thesis, the Regional Ocean Modelling System (ROMS) was applied to resolve high resolution (~1km) bay and shelf scale ocean processes along the south eastern coastline of South Africa using an offline multi-nested approach. Experimental and reference ocean model runs were used with in situ instrument mooring data to investigate how currents and temperature in the bays and the adjacent shelf are affected by the bathymetry, Agulhas Current (AC), regional winds, and coastal trapped waves (CTW). Focus was given to temperature, circulation, and coastal trapped waves, given the abundance of hourly in situ mooring data for these variables, making them suitable for comparison with the ocean model. SST variability trends were seasonally and spatially predictable, being greatest in the summer months and smallest in the winter months. A region of high SST variability extended from Port Alfred toward the south-west, indicating entrainment of nearshore upwelled water and instabilities in the inshore front of the AC. Shelf bottom temperature variability had a more spatially diverse seasonal trend, with coastal variability the highest (lowest) and offshore variability the lowest (highest) during the summer (winter) months. A distinct asymmetry in mean seasonal shelf bottom temperatures evident to the south of Algoa Bay and St Francis Bay was shown to be dependent on the profile of the shelf margin in relation to the inshore front of the AC using an experimental model run. Bay-scale anti-cyclonic circulation patterns dominate the bays throughout the year, with regions of strong mean surface currents occurring south of Cape Recife and Cape St Francis. General circulation patterns over the shelf are strongly governed by regional wind regimes, with the strongest flows being south-westward occurring during north-easterly wind events. Shelf bottom flows typically follow the expected Ekman-veering response, apart from near coastal flows that are topographically steered. A region of consistently strong south-westward shelf bottom flow extends from the east of Port Alfred to the shelf margin south of Bird Island. This flow is predominantly driven by the AC, although its velocity is strongly governed by regional winds. Circulation patterns during powerful eastward moving wind systems are strongly governed by the passage of associated CTW. Comparisons with an experimental model run where surface winds were removed revealed that the shelf wave was responsible for 61% of water volume displacement during a CTW event, and that the coastal shear turbulence caused by this displacement has a direct effect on the mixed layer depth. The links made between the complex shelf and bay ocean processes indicate that subtle changes to the ocean state will have far reaching effects on the regional ocean environment and its biota. Given the challenges of climate change, this is of paramount importance if we are to quantify these effects and mitigate their impacts, particularly with respect to the socio-economic dependency of those who rely on the ocean for its living resources.
- Full Text:
- Date Issued: 2020
- Authors: Bailey, Dylan Francis
- Date: 2020
- Subjects: Oceanography -- Research , Marine biology , Marine meteorology , Hydrography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49038 , vital:41595
- Description: There is a general need for a broader base of information on the finer detail of ocean processes in the Eastern Agulhas Bank region. In this thesis, the Regional Ocean Modelling System (ROMS) was applied to resolve high resolution (~1km) bay and shelf scale ocean processes along the south eastern coastline of South Africa using an offline multi-nested approach. Experimental and reference ocean model runs were used with in situ instrument mooring data to investigate how currents and temperature in the bays and the adjacent shelf are affected by the bathymetry, Agulhas Current (AC), regional winds, and coastal trapped waves (CTW). Focus was given to temperature, circulation, and coastal trapped waves, given the abundance of hourly in situ mooring data for these variables, making them suitable for comparison with the ocean model. SST variability trends were seasonally and spatially predictable, being greatest in the summer months and smallest in the winter months. A region of high SST variability extended from Port Alfred toward the south-west, indicating entrainment of nearshore upwelled water and instabilities in the inshore front of the AC. Shelf bottom temperature variability had a more spatially diverse seasonal trend, with coastal variability the highest (lowest) and offshore variability the lowest (highest) during the summer (winter) months. A distinct asymmetry in mean seasonal shelf bottom temperatures evident to the south of Algoa Bay and St Francis Bay was shown to be dependent on the profile of the shelf margin in relation to the inshore front of the AC using an experimental model run. Bay-scale anti-cyclonic circulation patterns dominate the bays throughout the year, with regions of strong mean surface currents occurring south of Cape Recife and Cape St Francis. General circulation patterns over the shelf are strongly governed by regional wind regimes, with the strongest flows being south-westward occurring during north-easterly wind events. Shelf bottom flows typically follow the expected Ekman-veering response, apart from near coastal flows that are topographically steered. A region of consistently strong south-westward shelf bottom flow extends from the east of Port Alfred to the shelf margin south of Bird Island. This flow is predominantly driven by the AC, although its velocity is strongly governed by regional winds. Circulation patterns during powerful eastward moving wind systems are strongly governed by the passage of associated CTW. Comparisons with an experimental model run where surface winds were removed revealed that the shelf wave was responsible for 61% of water volume displacement during a CTW event, and that the coastal shear turbulence caused by this displacement has a direct effect on the mixed layer depth. The links made between the complex shelf and bay ocean processes indicate that subtle changes to the ocean state will have far reaching effects on the regional ocean environment and its biota. Given the challenges of climate change, this is of paramount importance if we are to quantify these effects and mitigate their impacts, particularly with respect to the socio-economic dependency of those who rely on the ocean for its living resources.
- Full Text:
- Date Issued: 2020
On the development of ZnO nanorods on silicon substrate for light-emitting diode applications
- Djiokap, Stive Roussel Tankio
- 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.
- Full Text:
- Date Issued: 2018
- 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.
- Full Text:
- Date Issued: 2018
Optimising construction project role-player performance
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019