Synthesis, characterization and in vitro antiplasmodial evaluation of 4-& 8-aminoquinoline based-hybrid compounds
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
- Full Text:
- Date Issued: 2018
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
- Full Text:
- Date Issued: 2018
An investigation of the informal market value chain for prickly pear (Opuntia ficus-indica) in Nelson Mandela Bay, Eastern Cape
- Authors: Ntsonge, Sinazo
- Date: 2018
- Subjects: Opuntia ficus-indica -- South Africa -- Nelson Mandela Bay Municipality , Alien plants -- Economic aspects -- South Africa -- Nelson Mandela Bay Municipality , Women heads of households -- South Africa -- Nelson Mandela Bay Municipality , Poor -- South Africa -- Nelson Mandela Bay Municipality , Informal sector (Economics) -- South Africa -- Nelson Mandela Bay Municipality , Sustainable Livelihoods Framework
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62894 , vital:28308
- Description: The use of alien plant species as part of the livelihood resources of poor people raises conflicts with national legislation, which views these plants as threats to native plant biodiversity. However, there is also increasing body of literature on the contribution that some of these plants make to the livelihoods of poor people. The level of significance of some alien plant species to livelihoods is mostly highlighted in the case of female market participants who are in a position of household headship. Since most African cultures dictate the role of females as solely being that of homemaker while males are assigned the role household headship and breadwinner, women often find themselves having to shoulder the household responsibilities when the household head is no longer there. This was the case in the Nelson Mandela Bay informal prickly pear market that this study sought to investigate. Even though there were also male participants in the prickly pear market, the majority of participants in the market were female who also mentioned they were the sole breadwinner for their households. This study investigated the economic contribution that the prickly pear (Opuntia ficus-indica) informal market makes to the livelihoods of people living in the Nelson Mandela Bay. The significance of the market’s contribution to their livelihoods was examined through using the Sustainable Livelihoods Framework. The study revealed that although the prickly pear income was largely supplementary due to it being available for only three months of the year, the income was a safety net resource for the market participants who had limited access to other sources of income. The results also highlighted the reasons people were engaging in the informal prickly pear market. The main reason that was mentioned was unemployment. Through a livelihoods analysis using the Sustainable Livelihoods Framework, it was revealed that the other factors that were contributing to their unemployment were low levels of education, low levels of marketable skills, and old age. The study revealed through calculations of the estimated economic value of each market activity the potential of the prickly pear to be used as a poverty fighting tool. Although the results of this study only highlight the economic value of the prickly pear to people in a small area compared to the rest of the province and the country, the informal market’s significance still presents a strong case for the establishment of an agroprocessing industry, which would support the production of value-added products. Since the largest populations of the prickly pear in Uitenhage are currently under effective control by the cochineal species, promotion of its economic value instead of eradicating it without considering its value to the livelihoods of the people in the market could also ensure that its populations are kept under control. Job creation in the agroprocessing industry would not only improve the livelihoods of those involved in the market, but would also feed into the national economy instead of taking from it via the costs incurred during clearing.
- Full Text:
- Date Issued: 2018
- Authors: Ntsonge, Sinazo
- Date: 2018
- Subjects: Opuntia ficus-indica -- South Africa -- Nelson Mandela Bay Municipality , Alien plants -- Economic aspects -- South Africa -- Nelson Mandela Bay Municipality , Women heads of households -- South Africa -- Nelson Mandela Bay Municipality , Poor -- South Africa -- Nelson Mandela Bay Municipality , Informal sector (Economics) -- South Africa -- Nelson Mandela Bay Municipality , Sustainable Livelihoods Framework
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62894 , vital:28308
- Description: The use of alien plant species as part of the livelihood resources of poor people raises conflicts with national legislation, which views these plants as threats to native plant biodiversity. However, there is also increasing body of literature on the contribution that some of these plants make to the livelihoods of poor people. The level of significance of some alien plant species to livelihoods is mostly highlighted in the case of female market participants who are in a position of household headship. Since most African cultures dictate the role of females as solely being that of homemaker while males are assigned the role household headship and breadwinner, women often find themselves having to shoulder the household responsibilities when the household head is no longer there. This was the case in the Nelson Mandela Bay informal prickly pear market that this study sought to investigate. Even though there were also male participants in the prickly pear market, the majority of participants in the market were female who also mentioned they were the sole breadwinner for their households. This study investigated the economic contribution that the prickly pear (Opuntia ficus-indica) informal market makes to the livelihoods of people living in the Nelson Mandela Bay. The significance of the market’s contribution to their livelihoods was examined through using the Sustainable Livelihoods Framework. The study revealed that although the prickly pear income was largely supplementary due to it being available for only three months of the year, the income was a safety net resource for the market participants who had limited access to other sources of income. The results also highlighted the reasons people were engaging in the informal prickly pear market. The main reason that was mentioned was unemployment. Through a livelihoods analysis using the Sustainable Livelihoods Framework, it was revealed that the other factors that were contributing to their unemployment were low levels of education, low levels of marketable skills, and old age. The study revealed through calculations of the estimated economic value of each market activity the potential of the prickly pear to be used as a poverty fighting tool. Although the results of this study only highlight the economic value of the prickly pear to people in a small area compared to the rest of the province and the country, the informal market’s significance still presents a strong case for the establishment of an agroprocessing industry, which would support the production of value-added products. Since the largest populations of the prickly pear in Uitenhage are currently under effective control by the cochineal species, promotion of its economic value instead of eradicating it without considering its value to the livelihoods of the people in the market could also ensure that its populations are kept under control. Job creation in the agroprocessing industry would not only improve the livelihoods of those involved in the market, but would also feed into the national economy instead of taking from it via the costs incurred during clearing.
- Full Text:
- Date Issued: 2018
Investigation of the subsurface geology using time domain, magnetic and electrical resistivity geophysical techniques in the Karoo basin at Beaufort west, Western Cape Province, South Africa
- Authors: Ntunja, Asanda
- Date: 2018
- Subjects: Geology Geophysics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14659 , vital:40034
- Description: Beaufort West lies in the Central Karoo Basin and is specifically situated in the Poortjie Member of the Teekloof Formation in the Beaufort Group. The Teekloof Formation was deposited in a floodplain environment and it consists of alternating bluish grey mudstone and very fine to medium grained sandstone. The sediments of the Karoo Basin were intruded by numerous dolerite sills and dykes during a period of extensive magmatic activity over the whole South African subcontinent when the break-up of Gondwanda occurred. This led to a continuous jointing of the sedimentary rocks and the jointing resulted in rocks that are prone to weathering. Weathering that occurred in Beaufort West resulted in the formation of alluvium, calcrete, scree and hard pan deposits which overlay most of the ground surface. The joints in rocks paved way for groundwater storage in the sedimentary beds as sediments of the Karoo Basin lack significant primary porosity. Geophysical surveys were done in order to determine a suitable site to locate and drill a deep borehole to the White Hill Formation in order to extract shale gas that is proposed to be present in the area, thereafter determine sites for monitoring boreholes for groundwater and also look for area where potential groundwater might be present. This then requires geophysical investigations of the surface and subsurface geology of the area prior to drilling so as to locate any features such as dolerite intrusions which may hinder the drilling process and locate shallow aquifers, which will tend to be monitored before and during fracking. Five lines of varying lengths from 2-6 km and different orientation were surveyed using geophysical techniques which included the time domain, electrical resistivity as well as the magnetic methods. The geophysical investigations were conducted in order to fulfil the main vii objectives and aims of the study. The techniques were then complemented by XRF, petrography and density analyses. The time domain method reveals that Lines 1 and Line 2 comprises of rocks with low resistivity values of less than 30 Ωm. These two lines were more conductive towards the east and northeast side of the study site and the resistivity tends to increase towards the south and west. Line 4 appeared to be more conductive towards the south-east of the line. Lines 3 and 5 showed high resistivity values with Line 5 being the most resistive suggesting that the underlying strata is consolidated, dry and hard. The resistivity in all the lines surveyed showed an increase with increasing depth. The depth of investigation was approximately up to 150 m. The electrical resistivity results were only obtained from Line 1 and Line 2. The results, which complement the time domain results, suggest that the two lines indeed comprise of rocks which exhibit low resistivity values. This then implies that the rocks in the vicinity are fractured and the fractures might be field with groundwater and possibly contain some conductive minerals such as sodium oxide (Na2O) as supported by XRF results. This method also reveals that along Line 1, there are individual bodies of high resistivity values. The probing depth of about 78 m was achieved for the electrical resistivity survey. The magnetic data indicate that the magnetic intensity does not vary much across lines 3, 4 and 5 and there is not much change in lithology with depth and lateral extent. The area covered by Lines 1 and 2, and the additional eleven fill in lines has several prominent magnetic highs that are inferred to be due to dolerite intrusions in the sandstones and these bodies may be connected at depth. One of these anomalies which trends east-west direction partially coincides with a mapped dolerite intrusion. Some areas with sandstones also exhibit high viii magnetism which is due to about 3.3% content of Fe2O3 present in the sandstones as seen from XRF. This is probably resulted from weathering of magnetite in dolerite intrusions. Petrography results obtained from samples collected in the field reveal that there is an abundance of quartz in sandstones and siltstones. Quartz arenite also contained about 50% of feldspar, containing both plagioclase and K-feldspar. The sandstones of the Teekloof Formation (Beaufort West) have undergone calcite replacement where the calcite matrix replaced most or all of the clay matrix between the mineral grains. The fractures in rocks were seen and it was inferred that they are due to the present cleavages in feldspar and weathering of feldspar in sandstones. Through X-ray Fluorescence (XRF) analysis, it was revealed that the rocks contained a high percentage of Na2O. XRF also showed that these rocks were under low chemical weathering which led to the formation of new minerals in rock as other minerals such as feldspar weather away. This resulted in quartz being the most dominant mineral present as it is not prone to chemical weathering and thus the rocks were proven to be chemically matured. Thirty one rock samples were collected from the field in order to determine the density and porosity measurements. The fine to medium grained grey sandstones show an average density of 2.597 g/cm3 and a porosity of 1.4 %. The brownish grey sandstone have an average density of 2.546 g/cm3 and porosity of 2.9 % and the brown sandstones exhibit an average of 2.584 g/cm3 and a porosity 1.46 %. Dolerite has an average density of 2.970 g/cm3 and porosity of 0.5 % and siltstones have a density of 2.595 g/cm3 and porosity of 1.38 %. The brownish grey sandstones have the highest porosity and the grey sandstone and siltstone have the least porosity after the dolerite.
- Full Text:
- Date Issued: 2018
- Authors: Ntunja, Asanda
- Date: 2018
- Subjects: Geology Geophysics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14659 , vital:40034
- Description: Beaufort West lies in the Central Karoo Basin and is specifically situated in the Poortjie Member of the Teekloof Formation in the Beaufort Group. The Teekloof Formation was deposited in a floodplain environment and it consists of alternating bluish grey mudstone and very fine to medium grained sandstone. The sediments of the Karoo Basin were intruded by numerous dolerite sills and dykes during a period of extensive magmatic activity over the whole South African subcontinent when the break-up of Gondwanda occurred. This led to a continuous jointing of the sedimentary rocks and the jointing resulted in rocks that are prone to weathering. Weathering that occurred in Beaufort West resulted in the formation of alluvium, calcrete, scree and hard pan deposits which overlay most of the ground surface. The joints in rocks paved way for groundwater storage in the sedimentary beds as sediments of the Karoo Basin lack significant primary porosity. Geophysical surveys were done in order to determine a suitable site to locate and drill a deep borehole to the White Hill Formation in order to extract shale gas that is proposed to be present in the area, thereafter determine sites for monitoring boreholes for groundwater and also look for area where potential groundwater might be present. This then requires geophysical investigations of the surface and subsurface geology of the area prior to drilling so as to locate any features such as dolerite intrusions which may hinder the drilling process and locate shallow aquifers, which will tend to be monitored before and during fracking. Five lines of varying lengths from 2-6 km and different orientation were surveyed using geophysical techniques which included the time domain, electrical resistivity as well as the magnetic methods. The geophysical investigations were conducted in order to fulfil the main vii objectives and aims of the study. The techniques were then complemented by XRF, petrography and density analyses. The time domain method reveals that Lines 1 and Line 2 comprises of rocks with low resistivity values of less than 30 Ωm. These two lines were more conductive towards the east and northeast side of the study site and the resistivity tends to increase towards the south and west. Line 4 appeared to be more conductive towards the south-east of the line. Lines 3 and 5 showed high resistivity values with Line 5 being the most resistive suggesting that the underlying strata is consolidated, dry and hard. The resistivity in all the lines surveyed showed an increase with increasing depth. The depth of investigation was approximately up to 150 m. The electrical resistivity results were only obtained from Line 1 and Line 2. The results, which complement the time domain results, suggest that the two lines indeed comprise of rocks which exhibit low resistivity values. This then implies that the rocks in the vicinity are fractured and the fractures might be field with groundwater and possibly contain some conductive minerals such as sodium oxide (Na2O) as supported by XRF results. This method also reveals that along Line 1, there are individual bodies of high resistivity values. The probing depth of about 78 m was achieved for the electrical resistivity survey. The magnetic data indicate that the magnetic intensity does not vary much across lines 3, 4 and 5 and there is not much change in lithology with depth and lateral extent. The area covered by Lines 1 and 2, and the additional eleven fill in lines has several prominent magnetic highs that are inferred to be due to dolerite intrusions in the sandstones and these bodies may be connected at depth. One of these anomalies which trends east-west direction partially coincides with a mapped dolerite intrusion. Some areas with sandstones also exhibit high viii magnetism which is due to about 3.3% content of Fe2O3 present in the sandstones as seen from XRF. This is probably resulted from weathering of magnetite in dolerite intrusions. Petrography results obtained from samples collected in the field reveal that there is an abundance of quartz in sandstones and siltstones. Quartz arenite also contained about 50% of feldspar, containing both plagioclase and K-feldspar. The sandstones of the Teekloof Formation (Beaufort West) have undergone calcite replacement where the calcite matrix replaced most or all of the clay matrix between the mineral grains. The fractures in rocks were seen and it was inferred that they are due to the present cleavages in feldspar and weathering of feldspar in sandstones. Through X-ray Fluorescence (XRF) analysis, it was revealed that the rocks contained a high percentage of Na2O. XRF also showed that these rocks were under low chemical weathering which led to the formation of new minerals in rock as other minerals such as feldspar weather away. This resulted in quartz being the most dominant mineral present as it is not prone to chemical weathering and thus the rocks were proven to be chemically matured. Thirty one rock samples were collected from the field in order to determine the density and porosity measurements. The fine to medium grained grey sandstones show an average density of 2.597 g/cm3 and a porosity of 1.4 %. The brownish grey sandstone have an average density of 2.546 g/cm3 and porosity of 2.9 % and the brown sandstones exhibit an average of 2.584 g/cm3 and a porosity 1.46 %. Dolerite has an average density of 2.970 g/cm3 and porosity of 0.5 % and siltstones have a density of 2.595 g/cm3 and porosity of 1.38 %. The brownish grey sandstones have the highest porosity and the grey sandstone and siltstone have the least porosity after the dolerite.
- Full Text:
- Date Issued: 2018
Classification of Distinct Fuzzy Subgroups of the Dihedral Group Dp nq for p and q distinct primes and n ∈ N
- Authors: Nxala, Baphumelele Ellen
- Date: 2018
- Subjects: Fuzzy mathematics Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14516 , vital:39997
- Description: In this dissertation, we classify distinct fuzzy subgroups of the dihedral group Dpnq, for p and q distinct primes and n ∈ N, under a natural equivalence relation of fuzzy subgroups and a fuzzy isomorphism. We aim to present formulae for the number of maximal chains and the number of distinct fuzzy subgroups of this group. Our study will include some theory on non-abelian groups since the classification of distinct fuzzy subgroups of this group relies on the crisp characterization of maximal chains. We give the definition of a natural equivalence relation introduced by Murali and Makamba in [67] which we will use in this study. Based on this definition, we introduce two counting techniques that we will use to compute the number of distinct fuzzy subgroups of Dpnq. In this dissertation, we use the criss-cut counting technique as our primary method of enumeration, and the cross-cut method serves as a means of verifying results we obtain from our primary method. To classify distinct fuzzy subgroups of this group, we begin by investigating the dihedral groups Dpnq, for p and q distinct primes and specific values of n = 2 and 3 to observe a trend. We classify the flags of these groups using the characterization of flags introduced in [93]. From this characterization, we then present formulae for the number of distinct fuzzy subgroups attributed to the flags of Dp 2q and Dp 3q . To generalise results for Dpnq, for p and q distinct primes and n ∈ N, we characterize the flags of this group and classify them as either cyclic, mdcyclic for 1 ≤ m ≤ n, or b-cyclic. Finally, we establish a general formula for the number of distinct fuzzy subgroups obtainable from these flags. We conclude by comparing results obtained from using our general formula to those obtained by other researchers for the same group. Based on the results from this study, we give an outline of future research work
- Full Text:
- Date Issued: 2018
- Authors: Nxala, Baphumelele Ellen
- Date: 2018
- Subjects: Fuzzy mathematics Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14516 , vital:39997
- Description: In this dissertation, we classify distinct fuzzy subgroups of the dihedral group Dpnq, for p and q distinct primes and n ∈ N, under a natural equivalence relation of fuzzy subgroups and a fuzzy isomorphism. We aim to present formulae for the number of maximal chains and the number of distinct fuzzy subgroups of this group. Our study will include some theory on non-abelian groups since the classification of distinct fuzzy subgroups of this group relies on the crisp characterization of maximal chains. We give the definition of a natural equivalence relation introduced by Murali and Makamba in [67] which we will use in this study. Based on this definition, we introduce two counting techniques that we will use to compute the number of distinct fuzzy subgroups of Dpnq. In this dissertation, we use the criss-cut counting technique as our primary method of enumeration, and the cross-cut method serves as a means of verifying results we obtain from our primary method. To classify distinct fuzzy subgroups of this group, we begin by investigating the dihedral groups Dpnq, for p and q distinct primes and specific values of n = 2 and 3 to observe a trend. We classify the flags of these groups using the characterization of flags introduced in [93]. From this characterization, we then present formulae for the number of distinct fuzzy subgroups attributed to the flags of Dp 2q and Dp 3q . To generalise results for Dpnq, for p and q distinct primes and n ∈ N, we characterize the flags of this group and classify them as either cyclic, mdcyclic for 1 ≤ m ≤ n, or b-cyclic. Finally, we establish a general formula for the number of distinct fuzzy subgroups obtainable from these flags. We conclude by comparing results obtained from using our general formula to those obtained by other researchers for the same group. Based on the results from this study, we give an outline of future research work
- Full Text:
- Date Issued: 2018
A derivation of the the black-scholes equation using martingales
- Authors: Nyarko , Ebenezer Narh
- Date: 2018
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14572 , vital:40016
- Description: This work focuses on the application of stochastic differential equations, with martingales, in finance. The emphasis is on the derivation of the Black-Scholes model for the valuation of options. A theoretical framework in stochastic analysis, together with Itô calculus (Kiyoshi Itô), is explored. The Girsanov Theorem is applied in order to transform a modelled stochastic equation based, on predetermined stock and bond prices, into equivalent martingale measures. A replication strategy is then adopted to solve the two equations analytically, by finding the natural logarithm of the expectation of the solution to the stochastic models. We finally compute the resulting solution based on a standard, normal distribution to get the desired outcome of the Black-Scholes model.
- Full Text:
- Date Issued: 2018
- Authors: Nyarko , Ebenezer Narh
- Date: 2018
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14572 , vital:40016
- Description: This work focuses on the application of stochastic differential equations, with martingales, in finance. The emphasis is on the derivation of the Black-Scholes model for the valuation of options. A theoretical framework in stochastic analysis, together with Itô calculus (Kiyoshi Itô), is explored. The Girsanov Theorem is applied in order to transform a modelled stochastic equation based, on predetermined stock and bond prices, into equivalent martingale measures. A replication strategy is then adopted to solve the two equations analytically, by finding the natural logarithm of the expectation of the solution to the stochastic models. We finally compute the resulting solution based on a standard, normal distribution to get the desired outcome of the Black-Scholes model.
- Full Text:
- Date Issued: 2018
Corrosion resistance of nanocrystalline titanium zirconium nitride layers deposited on ZIRLO
- Nyembe, Hlanganani Siphelele
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2018
- Subjects: Zirconium alloys , Titanium alloys Nanocrystals Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34744 , vital:33435
- Description: Zirconium (Zr) alloys are used as nuclear fuel cladding in water-cooled nuclear reactors. Being in contact with steam, the Zr-alloy is oxidised and it absorbs hydrogen. The hydrogen pickup in Zr-alloys induces embrittlement of the tubes due to hydride formation. In this study, effectiveness of corrosion resistant nanocrystalline titanium zirconium nitride (nc-TiZrN) coatings on the surface of a Zr-alloy for the reduction of corrosion and hydrogen pickup is investigated. The nc-TiZrN layers were deposited onto the surface of ZIRLO® using the cathodic arc vapour deposition (CAVD) technique. The influence of nc-TiZrN coatings on the corrosion performance of ZIRLO® was investigated under the following conditions: (a) In an oxygen atmosphere at various temperatures from 400 to 900 ℃ for 30 minutes, (b) for various exposure times from 6 – 24 hours with the temperature kept constant at 500 ℃ in a tube furnace, and (c) in pure steam for 30 days at 360 ℃ and 18.7 MPa in an autoclave. The corrosion properties of the nc-TiZrN coated ZIRLO were compared to uncoated ZIRLO for all experiments. Following corrosion testing, the TiZrN coatings and oxide layers were investigated by scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiZrN coating had a thickness of ~3.8 μm with a small number of Ti-rich and Nb-rich inclusions. The coating exhibited a single phase solid solution of Ti0.42Zr0.58N with a NaCl-type crystal structure and columnar nanocrystals. These columnar nanocrystals showed a strong {111} preferred orientation and the {111} planes of the TiZrN crystals are oriented parallel to the (001) planes of α-ZIRLO grains with <001> direction perpendicular to the coating/ZIRLO interface. The corrosion testing at various temperatures from 400 to 900 ℃ for 30 minutes showed that the TiZrN coating oxidises slowly and retained its microstructure, composition and crystallinity up to 600 ℃. At higher temperatures above 600 ℃, the TiZrN layer completely oxidised to a non-protective TiZr-oxide layer and resulted in rapid corrosion of the underlying ZIRLO substrate. The rapid corrosion was not observed in the uncoated ZIRLO sample for all temperatures. The results of samples subjected to annealing treatment at 500 ℃ in an oxygen atmosphere at various times up to 24 hours revealed that the TiZrN layer oxidises faster than ZIRLO. This was confirmed by sub-cubic and sub-parabolic oxide growth kinetics observed in the uncoated ZIRLO which are slower than the parabolic kinetics of TiZrN coated samples. In all coated samples, the spallation was observed near the edges of the samples. The spallation was caused by rapid corrosion of the underlying ZIRLO substrate which resulted from the penetration of oxygen ions between the TiZrN coating and ZIRLO substrate along the edges of the samples. In pure steam for 30 days at 360 ℃, a complete loss of the TiZrN layer occurred but the results show that the coating might have delayed the corrosion of ZIRLO. In summary, corrosion resistance of nc-TiZrN coated ZIRLO was lower than that of uncoated ZIRLO. The study shows that the failure of TiZrN coatings leads to rapid corrosion of the underlying ZIRLO substrate which was not observed on the uncoated ZIRLO. It is not yet understood why the presence TiZrN coatings reduced the oxidation resistance of ZIRLO.
- Full Text:
- Date Issued: 2018
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2018
- Subjects: Zirconium alloys , Titanium alloys Nanocrystals Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34744 , vital:33435
- Description: Zirconium (Zr) alloys are used as nuclear fuel cladding in water-cooled nuclear reactors. Being in contact with steam, the Zr-alloy is oxidised and it absorbs hydrogen. The hydrogen pickup in Zr-alloys induces embrittlement of the tubes due to hydride formation. In this study, effectiveness of corrosion resistant nanocrystalline titanium zirconium nitride (nc-TiZrN) coatings on the surface of a Zr-alloy for the reduction of corrosion and hydrogen pickup is investigated. The nc-TiZrN layers were deposited onto the surface of ZIRLO® using the cathodic arc vapour deposition (CAVD) technique. The influence of nc-TiZrN coatings on the corrosion performance of ZIRLO® was investigated under the following conditions: (a) In an oxygen atmosphere at various temperatures from 400 to 900 ℃ for 30 minutes, (b) for various exposure times from 6 – 24 hours with the temperature kept constant at 500 ℃ in a tube furnace, and (c) in pure steam for 30 days at 360 ℃ and 18.7 MPa in an autoclave. The corrosion properties of the nc-TiZrN coated ZIRLO were compared to uncoated ZIRLO for all experiments. Following corrosion testing, the TiZrN coatings and oxide layers were investigated by scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiZrN coating had a thickness of ~3.8 μm with a small number of Ti-rich and Nb-rich inclusions. The coating exhibited a single phase solid solution of Ti0.42Zr0.58N with a NaCl-type crystal structure and columnar nanocrystals. These columnar nanocrystals showed a strong {111} preferred orientation and the {111} planes of the TiZrN crystals are oriented parallel to the (001) planes of α-ZIRLO grains with <001> direction perpendicular to the coating/ZIRLO interface. The corrosion testing at various temperatures from 400 to 900 ℃ for 30 minutes showed that the TiZrN coating oxidises slowly and retained its microstructure, composition and crystallinity up to 600 ℃. At higher temperatures above 600 ℃, the TiZrN layer completely oxidised to a non-protective TiZr-oxide layer and resulted in rapid corrosion of the underlying ZIRLO substrate. The rapid corrosion was not observed in the uncoated ZIRLO sample for all temperatures. The results of samples subjected to annealing treatment at 500 ℃ in an oxygen atmosphere at various times up to 24 hours revealed that the TiZrN layer oxidises faster than ZIRLO. This was confirmed by sub-cubic and sub-parabolic oxide growth kinetics observed in the uncoated ZIRLO which are slower than the parabolic kinetics of TiZrN coated samples. In all coated samples, the spallation was observed near the edges of the samples. The spallation was caused by rapid corrosion of the underlying ZIRLO substrate which resulted from the penetration of oxygen ions between the TiZrN coating and ZIRLO substrate along the edges of the samples. In pure steam for 30 days at 360 ℃, a complete loss of the TiZrN layer occurred but the results show that the coating might have delayed the corrosion of ZIRLO. In summary, corrosion resistance of nc-TiZrN coated ZIRLO was lower than that of uncoated ZIRLO. The study shows that the failure of TiZrN coatings leads to rapid corrosion of the underlying ZIRLO substrate which was not observed on the uncoated ZIRLO. It is not yet understood why the presence TiZrN coatings reduced the oxidation resistance of ZIRLO.
- Full Text:
- Date Issued: 2018
Characterisation of surfaces modified with phthalocyanines through click chemistry for applications in electrochemical sensing
- O'Donoghue, Charles St John Nqwabuko
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
- Date Issued: 2018
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
- Date Issued: 2018
A congestion aware ant colony optimisation-based routing and wavelength assignment algorithm for transparent flexi-grid optical burst switched networks
- Authors: Oladipo, Joshua Femi
- Date: 2018
- Subjects: Ants -- Behavior -- Mathematical models , Distributed algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34733 , vital:33432
- Description: Optical Burst Switching (OBS) over transparent exi-grid optical networks, is considered a potential solution to the increasing pressure on backbone networks due to the increase in internet use and widespread adoption of various high bandwidth applications. Both technologies allow for more e cient usage of a networks resources. However, transmissions over exi-grid networks are more susceptible to optical impairments than transmissions made over xed-grid networks, and OBS suers from high burst loss due to contention. These issues need to be solved in order to reap the full benets of both technologies. An open issue for OBS whose solution would mitigate both issues is the Routing and Wavelength Assignment (RWA) algorithm. Ant Colony Optimisation (ACO) is a method of interest for solving the RWA problem on OBS networks. This study aims to improve on current dynamic ACO-based solutions to the Routing and Wavelength Assignment problem on transparent exi-grid Optical Burst Switched networks.
- Full Text:
- Date Issued: 2018
- Authors: Oladipo, Joshua Femi
- Date: 2018
- Subjects: Ants -- Behavior -- Mathematical models , Distributed algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34733 , vital:33432
- Description: Optical Burst Switching (OBS) over transparent exi-grid optical networks, is considered a potential solution to the increasing pressure on backbone networks due to the increase in internet use and widespread adoption of various high bandwidth applications. Both technologies allow for more e cient usage of a networks resources. However, transmissions over exi-grid networks are more susceptible to optical impairments than transmissions made over xed-grid networks, and OBS suers from high burst loss due to contention. These issues need to be solved in order to reap the full benets of both technologies. An open issue for OBS whose solution would mitigate both issues is the Routing and Wavelength Assignment (RWA) algorithm. Ant Colony Optimisation (ACO) is a method of interest for solving the RWA problem on OBS networks. This study aims to improve on current dynamic ACO-based solutions to the Routing and Wavelength Assignment problem on transparent exi-grid Optical Burst Switched networks.
- Full Text:
- Date Issued: 2018
Isolation and characterization of E. coli and Campylobacter spp. from diarrhoeal samples collected from selected hospitals in Amathole District Municipality, Eastern Cape, South Africa
- Authors: Omolajaiye, Sunday Abraham
- Date: 2018
- Subjects: Escherichia coli infections Campylobacter infections Diarrhea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6213 , vital:29515
- Description: Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.
- Full Text:
- Date Issued: 2018
- Authors: Omolajaiye, Sunday Abraham
- Date: 2018
- Subjects: Escherichia coli infections Campylobacter infections Diarrhea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6213 , vital:29515
- Description: Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.
- Full Text:
- Date Issued: 2018
Quantification of water resources uncertainties in two sub-basins of the Limpopo River basin
- Authors: Oosthuizen, Nadia
- Date: 2018
- Subjects: Hydrologic models -- Limpopo River Watershed , Water-supply -- Limpopo River Watershed , Water-supply -- Management , Sustainable development , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Reservoirs -- Limpopo River Watershed
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63267 , vital:28388
- Description: The demand for water is rapidly growing, placing more strain on access to the resources and subsequently its management. For sustainable management, there is a need to accurately quantify the available water resources. Unfortunately, the data required for such assessments are frequently far from sufficient in terms of availability and quality, especially in southern Africa. In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. Such data is however, often inadequate in many sub-basins necessitating the incorporation of the uncertainty related to the estimation process. Model parameter estimation and input data are significant sources of uncertainty that should be quantified. Also, in southern Africa water use data are unreliable because available databases consist of licensed information and actual use is generally unknown. In this study, the water resources of two sub-basins of the Limpopo River basin – the Mogalakwena in South Africa and the Shashe shared between Botswana and Zimbabwe – are estimated. The study assessed how uncertainties in the Pitman model parameterisation and input water use data affect the estimation of surface water resources of the selected sub-basins. Farm reservoirs and irrigated areas data from various sources were collected and used to run the Pitman model. Results indicate that the total model output uncertainty is higher for the Shashe sub-basin which is more data scarce than the Mogalakwena sub-basin. The study illustrates the importance of including uncertainty in the water resources assessment process to provide baseline data for decision making in resource management and planning. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 22.6 Mm3 and 24.7 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased to between 22.2 Mm3 and 25.0 Mm3 when anthropogenic water use data such as small farm and large reservoirs and irrigation were included. The flows generated for Shashe was between 11.7 Mm3 and 14.5 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The predictive uncertainty of the model changed to 11.7 Mm3 and 17.7 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.
- Full Text:
- Date Issued: 2018
- Authors: Oosthuizen, Nadia
- Date: 2018
- Subjects: Hydrologic models -- Limpopo River Watershed , Water-supply -- Limpopo River Watershed , Water-supply -- Management , Sustainable development , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Reservoirs -- Limpopo River Watershed
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63267 , vital:28388
- Description: The demand for water is rapidly growing, placing more strain on access to the resources and subsequently its management. For sustainable management, there is a need to accurately quantify the available water resources. Unfortunately, the data required for such assessments are frequently far from sufficient in terms of availability and quality, especially in southern Africa. In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. Such data is however, often inadequate in many sub-basins necessitating the incorporation of the uncertainty related to the estimation process. Model parameter estimation and input data are significant sources of uncertainty that should be quantified. Also, in southern Africa water use data are unreliable because available databases consist of licensed information and actual use is generally unknown. In this study, the water resources of two sub-basins of the Limpopo River basin – the Mogalakwena in South Africa and the Shashe shared between Botswana and Zimbabwe – are estimated. The study assessed how uncertainties in the Pitman model parameterisation and input water use data affect the estimation of surface water resources of the selected sub-basins. Farm reservoirs and irrigated areas data from various sources were collected and used to run the Pitman model. Results indicate that the total model output uncertainty is higher for the Shashe sub-basin which is more data scarce than the Mogalakwena sub-basin. The study illustrates the importance of including uncertainty in the water resources assessment process to provide baseline data for decision making in resource management and planning. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 22.6 Mm3 and 24.7 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased to between 22.2 Mm3 and 25.0 Mm3 when anthropogenic water use data such as small farm and large reservoirs and irrigation were included. The flows generated for Shashe was between 11.7 Mm3 and 14.5 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The predictive uncertainty of the model changed to 11.7 Mm3 and 17.7 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.
- Full Text:
- Date Issued: 2018
Development and assessment of gastroretentive sustained release captopril micro-balloons
- Authors: Oridota, Omoyosola Omolola
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63491 , vital:28419
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Oridota, Omoyosola Omolola
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63491 , vital:28419
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
The influence of construction project managers’ experience on project performance: the case of Nelson Mandela Bay infrastructure projects
- Authors: Parazee, Viahn
- Date: 2018
- Subjects: Infrastructure (Economics) -- South Africa -- Nelson Mandela Bay Municipality , Economic development projects -- South Africa -- Nelson Mandela Bay Municipality -- Management Public works -- South Africa -- Nelson Mandela Bay Municipality -- Management Project Management -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34510 , vital:33387
- Description: When you start out in the engineering industry especially in the public sector, one seldom has the mentorship required to equip you with the skills to succeed in successfully implementing projects. It has furthermore been observed that there is a major difference between project management competencies and merely having a qualification in the same field as the project’s core business. The role of Construction Project Managers is especially unique within public sector projects as these projects often involve multiple stakeholders whose opinions can strongly influence the project(Jalocha et al., 2014). This has been the case within the Nelson Mandela Bay Municipality where labour and community unrest often result in project stoppages and delays which ultimately lead to project failure. Stakeholder engagement, an inherently social competence, is a key component of Project Management Competence and falls outside the curriculum of most technical qualifications in the built environment. Project Management failure within the public sector has become rife and the research findings of this study should be helpful in assisting the local government in attaining higher project success rates. A qualitative research approach was adopted for this study making use of a descriptive research design, yielding qualitative data which was summarised by the researcher through statistical analyses. The data were obtained through questionnaires distributed to the various Clients, Consultants and Contractors within the NMBM via email. The questionnaires were furthermore only distributed to government parastatals within the construction industry in the NMBM, Consultants and Contractors who have completed or are working on projects for these parastatals within the public sector. Key findings from the research note a positive relationship between competency and project success; that there is not enough mentorship received by Construction Project Managers in the built environment sectors; that there is a positive relationship between mentorship received and project success and that there is a significant difference in the number of professionally registered personnel in the Consulting Sector compared to that of the Public-Sector. It furthermore indicated that there was a positive correlation between supervisors being professionally registered and their junior Construction Project Managers achieving project success from the research findings, recommendations were made to aid the increase in project success rates and decrease project management failure within the NMBM. For this to be achieved, the following areas need to be addressed: Assigning of projects to Construction Project Managers, Mentorship provided to Construction Project Managers and ultimately their Project Management Competence.
- Full Text:
- Date Issued: 2018
- Authors: Parazee, Viahn
- Date: 2018
- Subjects: Infrastructure (Economics) -- South Africa -- Nelson Mandela Bay Municipality , Economic development projects -- South Africa -- Nelson Mandela Bay Municipality -- Management Public works -- South Africa -- Nelson Mandela Bay Municipality -- Management Project Management -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34510 , vital:33387
- Description: When you start out in the engineering industry especially in the public sector, one seldom has the mentorship required to equip you with the skills to succeed in successfully implementing projects. It has furthermore been observed that there is a major difference between project management competencies and merely having a qualification in the same field as the project’s core business. The role of Construction Project Managers is especially unique within public sector projects as these projects often involve multiple stakeholders whose opinions can strongly influence the project(Jalocha et al., 2014). This has been the case within the Nelson Mandela Bay Municipality where labour and community unrest often result in project stoppages and delays which ultimately lead to project failure. Stakeholder engagement, an inherently social competence, is a key component of Project Management Competence and falls outside the curriculum of most technical qualifications in the built environment. Project Management failure within the public sector has become rife and the research findings of this study should be helpful in assisting the local government in attaining higher project success rates. A qualitative research approach was adopted for this study making use of a descriptive research design, yielding qualitative data which was summarised by the researcher through statistical analyses. The data were obtained through questionnaires distributed to the various Clients, Consultants and Contractors within the NMBM via email. The questionnaires were furthermore only distributed to government parastatals within the construction industry in the NMBM, Consultants and Contractors who have completed or are working on projects for these parastatals within the public sector. Key findings from the research note a positive relationship between competency and project success; that there is not enough mentorship received by Construction Project Managers in the built environment sectors; that there is a positive relationship between mentorship received and project success and that there is a significant difference in the number of professionally registered personnel in the Consulting Sector compared to that of the Public-Sector. It furthermore indicated that there was a positive correlation between supervisors being professionally registered and their junior Construction Project Managers achieving project success from the research findings, recommendations were made to aid the increase in project success rates and decrease project management failure within the NMBM. For this to be achieved, the following areas need to be addressed: Assigning of projects to Construction Project Managers, Mentorship provided to Construction Project Managers and ultimately their Project Management Competence.
- Full Text:
- Date Issued: 2018
Project management in the Mauritian construction industry
- Paurobally, Mohamad Ali Zeeshan
- Authors: Paurobally, Mohamad Ali Zeeshan
- Date: 2018
- Subjects: Project management -- Mauritius , Construction industry -- Mauritius Construction industry -- Forecasting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34499 , vital:33386
- Description: The main objective of this research study was to find out the various factors affecting the success of projects, with specific reference to the client’s related factors, consultant’s related and main contractor’s related factors. Completion of the construction project within the required cost, time and quality parameters was identified as the motivation for the study. The objectives of the study were achieved by reviewing literature relevant to the topic. The study investigated whether certain assumptions being made were corresponding with already published literature. Data were sourced both from primary and secondary sources. The quantitative part of the research was carried out by analyzing the literature and by envisaging possible scenarios which could be implemented for the completion of projects, within the three parameters (Time, cost and quality). Not being able to complete a project within the required cost, time and quality parameters will ultimately result in time and cost overruns up to the dissatisfaction of the client. As such, the various stages of the construction cycle need to be monitored and controlled as from the inception stage up to the close out stage by the various stakeholders involved on the project in order to obtain a positive project outcome. The research sample was focused mainly on professionals in the built environment, since a better understanding and reliable feedback would be obtained due to their understanding of the relevant topic. The study first introduces project management as a background, and then focuses on the different factors that influence successful project outcome.
- Full Text:
- Date Issued: 2018
- Authors: Paurobally, Mohamad Ali Zeeshan
- Date: 2018
- Subjects: Project management -- Mauritius , Construction industry -- Mauritius Construction industry -- Forecasting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34499 , vital:33386
- Description: The main objective of this research study was to find out the various factors affecting the success of projects, with specific reference to the client’s related factors, consultant’s related and main contractor’s related factors. Completion of the construction project within the required cost, time and quality parameters was identified as the motivation for the study. The objectives of the study were achieved by reviewing literature relevant to the topic. The study investigated whether certain assumptions being made were corresponding with already published literature. Data were sourced both from primary and secondary sources. The quantitative part of the research was carried out by analyzing the literature and by envisaging possible scenarios which could be implemented for the completion of projects, within the three parameters (Time, cost and quality). Not being able to complete a project within the required cost, time and quality parameters will ultimately result in time and cost overruns up to the dissatisfaction of the client. As such, the various stages of the construction cycle need to be monitored and controlled as from the inception stage up to the close out stage by the various stakeholders involved on the project in order to obtain a positive project outcome. The research sample was focused mainly on professionals in the built environment, since a better understanding and reliable feedback would be obtained due to their understanding of the relevant topic. The study first introduces project management as a background, and then focuses on the different factors that influence successful project outcome.
- Full Text:
- Date Issued: 2018
Interactions between three biological control agents of water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae) in South Africa
- Authors: Petela, Nomvume
- Date: 2018
- Subjects: Water hyacinth -- South Africa , Water hyacinth -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Curculionidae , Delphacidae , Miridae , Neochetina eichhorniae Warner , Megamelus scutellaris Berg , Eccritotarsus eichhorniae Henry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60676 , vital:27814
- Description: Water hyacinth, Eichhomia crassipes (Mart.) Solms (Pontederiaceae) is a free-floating perennial weed that is regarded as the worst aquatic weed in the world because of its negative impacts on aquatic ecosystems. It is native to the Amazon Basin of South America, but since the late 1800s has spread throughout the world. The first record of the weed in South Africa was noted in 1908 on the Cape Flats and in KwaZulu-Natal, but it is now dispersed throughout the country. Mechanical and chemical control methods have been used against the weed, but biological control is considered the most cost-effective, sustainable and environmentally friendly intervention. Currently, nine biological control agents have been released against water hyacinth in South Africa, and Neochetina eichhorniae Warner (Coleoptera: Curculionidae) is used most widely to control it. However, in some sites, water hyacinth mats have still not been brought under control because of eutrophic waters and cool temperatures. It was therefore necessary to release new biological control agents to complement the impact of N. eichhorniae. Megamelus scutellaris Berg (Hemiptera: Delphacidae) was released in 2013, but little is known about how it interacts with other agents already present in South Africa. It is likely to compete with the established biological control agent, Eccritotarsus eichhorniae Henry (Heteroptera: Miridae), because they are both sap suckers. On the other hand, N. eichhorniae is the most widespread and thus the most important biological control agent for water hyacinth. The aim of this study, then, was to determine the interactions between the two sap-sucking agents in South Africa that presumably occupy similar niches on the plant, and the interaction between M. scutellerais and N. eichhorniae, the most widely distributed and abundant agent in South Africa. Three experiments were conducted at the Waainek Research Facility at Rhodes University, Grahamstown, Eastern Cape, South Africa. Plants were grown for two weeks and insect species were inoculated singly or in combination. Water hyacinth, plant growth parameters and insect parameters were measured every 14 days for a period of 12 weeks. The results of the study showed that feeding by either E. eichhorniae or M. scutellaris had no effect on the feeding of the other agent. Both agents reduced all the measured plant growth parameters equally, either singly or in combination (i.e. E. eichhorniae or M. scutellaris alone or together). The interaction between the two agents appears neutral and agents are likely to complement each other in the field. Prior feeding by E. eichhorniae or M. scutellaris on water hyacinth did not affect the subsequent feeding by either agent. Megamelus scutellaris prefers healthy fresh water hyacinth plants. In addition, planthoppers performed best in combination with the weevil, especially on plants with new weevil feeding scars. The results of the study showed that M. scutellaris is compatible with other biological control agents of water hyacinth that are already established in South Africa. Therefore, the introduction of M. scutellaris may enhance the biological control of water hyacinth in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Petela, Nomvume
- Date: 2018
- Subjects: Water hyacinth -- South Africa , Water hyacinth -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Curculionidae , Delphacidae , Miridae , Neochetina eichhorniae Warner , Megamelus scutellaris Berg , Eccritotarsus eichhorniae Henry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60676 , vital:27814
- Description: Water hyacinth, Eichhomia crassipes (Mart.) Solms (Pontederiaceae) is a free-floating perennial weed that is regarded as the worst aquatic weed in the world because of its negative impacts on aquatic ecosystems. It is native to the Amazon Basin of South America, but since the late 1800s has spread throughout the world. The first record of the weed in South Africa was noted in 1908 on the Cape Flats and in KwaZulu-Natal, but it is now dispersed throughout the country. Mechanical and chemical control methods have been used against the weed, but biological control is considered the most cost-effective, sustainable and environmentally friendly intervention. Currently, nine biological control agents have been released against water hyacinth in South Africa, and Neochetina eichhorniae Warner (Coleoptera: Curculionidae) is used most widely to control it. However, in some sites, water hyacinth mats have still not been brought under control because of eutrophic waters and cool temperatures. It was therefore necessary to release new biological control agents to complement the impact of N. eichhorniae. Megamelus scutellaris Berg (Hemiptera: Delphacidae) was released in 2013, but little is known about how it interacts with other agents already present in South Africa. It is likely to compete with the established biological control agent, Eccritotarsus eichhorniae Henry (Heteroptera: Miridae), because they are both sap suckers. On the other hand, N. eichhorniae is the most widespread and thus the most important biological control agent for water hyacinth. The aim of this study, then, was to determine the interactions between the two sap-sucking agents in South Africa that presumably occupy similar niches on the plant, and the interaction between M. scutellerais and N. eichhorniae, the most widely distributed and abundant agent in South Africa. Three experiments were conducted at the Waainek Research Facility at Rhodes University, Grahamstown, Eastern Cape, South Africa. Plants were grown for two weeks and insect species were inoculated singly or in combination. Water hyacinth, plant growth parameters and insect parameters were measured every 14 days for a period of 12 weeks. The results of the study showed that feeding by either E. eichhorniae or M. scutellaris had no effect on the feeding of the other agent. Both agents reduced all the measured plant growth parameters equally, either singly or in combination (i.e. E. eichhorniae or M. scutellaris alone or together). The interaction between the two agents appears neutral and agents are likely to complement each other in the field. Prior feeding by E. eichhorniae or M. scutellaris on water hyacinth did not affect the subsequent feeding by either agent. Megamelus scutellaris prefers healthy fresh water hyacinth plants. In addition, planthoppers performed best in combination with the weevil, especially on plants with new weevil feeding scars. The results of the study showed that M. scutellaris is compatible with other biological control agents of water hyacinth that are already established in South Africa. Therefore, the introduction of M. scutellaris may enhance the biological control of water hyacinth in South Africa.
- Full Text:
- Date Issued: 2018
Cost and time overruns on Mpumalanga Province infrastructure projects
- Authors: Phalanndwa, Shonisani Aaron
- Date: 2018
- Subjects: Project management -- South Africa -- Mpumalanga , Infrastructure (Economics) industrial management -- South Africa -- Mpumalanga Business enterprises -- South Africa -- Mpumalanga -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34169 , vital:33248
- Description: Cost and time overruns in construction projects are a common issue affecting project performance, and Mpumalanga is no exception. Completion of any project within the estimated cost of a project is a basic criterion for success of any project. The success of any project highly depends on adequate availability and efficient management of various resources. Construction projects often face a lot of uncertainties, which places building construction projects at the risk of cost, time overruns as well as poor quality delivery. This study assesses the causes, effects and measures of minimising construction project cost and time overrun in the Mpumalanga Province. The data used in this study were derived from both primary and secondary sources. The primary data was collected through case study interviews with construction professionals, project owners, contractors and consultants involved in Mpumalanga construction projects. Findings from the case study revealed that clients inability to meet payment obligations on time, additional work requested by the client, proper feasibility study not done, ensuring transparency in awarding of contracts, contractors financial difficulties, late delivery of materials, contractors lack of experience, bribery and corruption involving the contractor or contractor’s team, and poor site management and consultants insufficient geotechnical investigations, insufficient/unknown information regarding site conditions during design phase, mistakes and discrepancies in design documents are the major causes of cost and time overruns that are incidental to project implementation in Mpumalanga. Furthermore the study also reveals that the major effect of cost and time overrun are: poor quality workmanship, total abandonment, and disputes, discouragement of investors, community unrest and service delivery is negatively affected. It was revealed that all stakeholders of construction parties are deeply involved in contributing to the causes of the problems, clients should bear the greatest responsibility and play the most important role in lessening the impact of cost and time overrun. Thus, interventions that could be adopted by the Mpumalanga province to achieve project delivery that is within estimated cost and time are: Government must adopt ‘financial assignment’ to deal with suppliers in order to supply materials to the contractor and have available funds for projects on time, soil investigation and testing should be conducted by clients prior to the commencement of a project; encourage whistleblowing and punish fraudsters more severely. Contractors must have enough cash before commencing of projects, v monitor financial spending of the projects and payments; consultants must review and approve design documents, shop drawings, and payments of contractor. It is recommended that training courses, seminars and workshops on project management should be made available to help improve the abilities of construction teams responsible for management and supervision of sites and client organisations should encourage whistleblowing, punish fraudsters more efficiently and pay commensurate reward to whistle-blowers in order to minimise cost and time overruns.
- Full Text:
- Date Issued: 2018
- Authors: Phalanndwa, Shonisani Aaron
- Date: 2018
- Subjects: Project management -- South Africa -- Mpumalanga , Infrastructure (Economics) industrial management -- South Africa -- Mpumalanga Business enterprises -- South Africa -- Mpumalanga -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34169 , vital:33248
- Description: Cost and time overruns in construction projects are a common issue affecting project performance, and Mpumalanga is no exception. Completion of any project within the estimated cost of a project is a basic criterion for success of any project. The success of any project highly depends on adequate availability and efficient management of various resources. Construction projects often face a lot of uncertainties, which places building construction projects at the risk of cost, time overruns as well as poor quality delivery. This study assesses the causes, effects and measures of minimising construction project cost and time overrun in the Mpumalanga Province. The data used in this study were derived from both primary and secondary sources. The primary data was collected through case study interviews with construction professionals, project owners, contractors and consultants involved in Mpumalanga construction projects. Findings from the case study revealed that clients inability to meet payment obligations on time, additional work requested by the client, proper feasibility study not done, ensuring transparency in awarding of contracts, contractors financial difficulties, late delivery of materials, contractors lack of experience, bribery and corruption involving the contractor or contractor’s team, and poor site management and consultants insufficient geotechnical investigations, insufficient/unknown information regarding site conditions during design phase, mistakes and discrepancies in design documents are the major causes of cost and time overruns that are incidental to project implementation in Mpumalanga. Furthermore the study also reveals that the major effect of cost and time overrun are: poor quality workmanship, total abandonment, and disputes, discouragement of investors, community unrest and service delivery is negatively affected. It was revealed that all stakeholders of construction parties are deeply involved in contributing to the causes of the problems, clients should bear the greatest responsibility and play the most important role in lessening the impact of cost and time overrun. Thus, interventions that could be adopted by the Mpumalanga province to achieve project delivery that is within estimated cost and time are: Government must adopt ‘financial assignment’ to deal with suppliers in order to supply materials to the contractor and have available funds for projects on time, soil investigation and testing should be conducted by clients prior to the commencement of a project; encourage whistleblowing and punish fraudsters more severely. Contractors must have enough cash before commencing of projects, v monitor financial spending of the projects and payments; consultants must review and approve design documents, shop drawings, and payments of contractor. It is recommended that training courses, seminars and workshops on project management should be made available to help improve the abilities of construction teams responsible for management and supervision of sites and client organisations should encourage whistleblowing, punish fraudsters more efficiently and pay commensurate reward to whistle-blowers in order to minimise cost and time overruns.
- Full Text:
- Date Issued: 2018
Reducing the brittleness of poly-furfuryl alcohol resin used in composites
- Authors: Pillay, Princeton
- Date: 2018
- Subjects: Textile chemistry , Textile chemicals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34350 , vital:33339
- Description: The thermoset market is dominated with petroleum-based products. The rising concerns on depletion of non-renewable resources and climate change has motivated researches and industries to find green alternatives for petroleum based materials. The thermoset polymer poly-furfuryl alcohol (PFA) displays good chemical, viscoelastic and moisture stability properties and importantly is bio-based, however, the cured PFA resin is very brittle. The approach of incorporating different types of particulate fillers into the PFA matrix and reinforcing the PFA matrix with flax fabric was used to address the brittleness issue associated with PFA. In the first study, flax fabric was treated with a diammonium phosphate based flame-retardant to reduce the flammability. Compression moulding was used to produce PFA biocomposites and PFA laminates. The effect of the flame-retardant was investigated using Scanning electron microscope (SEM), x-ray diffraction (XRD), fourier transform infrared (FTIR), and cone calorimeter, flexural and tensile tests. The flame-retardant treatment significantly improved the flammability properties, however, decreased the flexural and tensile properties. In the second study, 10 different fillers were selected, these being; ZnO, Clay, montmorillonite (MMT), Rubber, Chitin, Starch, CaCO3, Chitosan, Lignin and TiO2. These fillers were incorporated into the PFA resin at 2% and 5% concentration and reinforced with untreated (UT) flax fabric and flame-retardant (FR) treated flax fabric. Flexural, tensile and izod impact tests were performed on the cured laminates. Thermogravimetric analysis (TGA), SEM and micro x-ray computed tomography scan (CT scan) analysis was performed on selected samples. The inclusion of MMT and Rubber significantly increased the strength and the stiffness of the PFA/UT-Flax laminate while Clay and ZnO reduced the brittleness of the PFA/UT-Flax laminate. FR laminates generally exhibited poor mechanical properties regardless of the type of filler. This was the result of FR damaging the flax fibres during the compression moulding process and hindered the interaction between the PFA matrix and flax fabric. TGA results showed that FR treatment increased the thermal stability of the PFA laminate. SEM and CT scan analysis illustrated the large amount of voids between fabric layers, especially for UT-Flax laminates. The fillers MMT, Rubber and ZnO had a positive effect on the mechanical properties of UT-Flax laminates and therefore were used in the third study. A Box Behnken design of experiment was developed in which the concentration of MMT, Rubber and ZnO was varied between 0 – 5%. Multiple linear regression was used to model the mechanical properties of the PFA/UT-Flax laminates based on a full quadratic model. An optimized filler combination was determined with Solver ®. The experimental results of the optimised PFA/UT-Flax laminate were compared to the values predicted with the statistical model.
- Full Text:
- Date Issued: 2018
- Authors: Pillay, Princeton
- Date: 2018
- Subjects: Textile chemistry , Textile chemicals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34350 , vital:33339
- Description: The thermoset market is dominated with petroleum-based products. The rising concerns on depletion of non-renewable resources and climate change has motivated researches and industries to find green alternatives for petroleum based materials. The thermoset polymer poly-furfuryl alcohol (PFA) displays good chemical, viscoelastic and moisture stability properties and importantly is bio-based, however, the cured PFA resin is very brittle. The approach of incorporating different types of particulate fillers into the PFA matrix and reinforcing the PFA matrix with flax fabric was used to address the brittleness issue associated with PFA. In the first study, flax fabric was treated with a diammonium phosphate based flame-retardant to reduce the flammability. Compression moulding was used to produce PFA biocomposites and PFA laminates. The effect of the flame-retardant was investigated using Scanning electron microscope (SEM), x-ray diffraction (XRD), fourier transform infrared (FTIR), and cone calorimeter, flexural and tensile tests. The flame-retardant treatment significantly improved the flammability properties, however, decreased the flexural and tensile properties. In the second study, 10 different fillers were selected, these being; ZnO, Clay, montmorillonite (MMT), Rubber, Chitin, Starch, CaCO3, Chitosan, Lignin and TiO2. These fillers were incorporated into the PFA resin at 2% and 5% concentration and reinforced with untreated (UT) flax fabric and flame-retardant (FR) treated flax fabric. Flexural, tensile and izod impact tests were performed on the cured laminates. Thermogravimetric analysis (TGA), SEM and micro x-ray computed tomography scan (CT scan) analysis was performed on selected samples. The inclusion of MMT and Rubber significantly increased the strength and the stiffness of the PFA/UT-Flax laminate while Clay and ZnO reduced the brittleness of the PFA/UT-Flax laminate. FR laminates generally exhibited poor mechanical properties regardless of the type of filler. This was the result of FR damaging the flax fibres during the compression moulding process and hindered the interaction between the PFA matrix and flax fabric. TGA results showed that FR treatment increased the thermal stability of the PFA laminate. SEM and CT scan analysis illustrated the large amount of voids between fabric layers, especially for UT-Flax laminates. The fillers MMT, Rubber and ZnO had a positive effect on the mechanical properties of UT-Flax laminates and therefore were used in the third study. A Box Behnken design of experiment was developed in which the concentration of MMT, Rubber and ZnO was varied between 0 – 5%. Multiple linear regression was used to model the mechanical properties of the PFA/UT-Flax laminates based on a full quadratic model. An optimized filler combination was determined with Solver ®. The experimental results of the optimised PFA/UT-Flax laminate were compared to the values predicted with the statistical model.
- Full Text:
- Date Issued: 2018
Primary controls on iron and manganese distribution in sphalerite of the Gams Formation, Gamsberg zinc deposit, Namaqualand, South Africa
- Authors: Poignant-Molina, Léo
- Date: 2018
- Subjects: Sphalerite , Sphalerite South Africa Gamsberg , Manganese South Africa Gamsberg , Zinc mines and mining South Africa Gamsberg , Geochemistry South Africa Gamsberg , Metamorphism (Geology) , Electron probe microanalysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63775 , vital:28488
- Description: The Gamsberg deposit is a 200 Mt zinc reserve belonging to the world class base metalrich Aggeneys-Gamsberg mining district. A rifting environment permitted the development of four proximal SEDEX-type deposits whereby Gamsberg is localized in the eastern side of the district and characterised by a peculiar enrichment in manganese. This study investigates the geochemistry of sphalerite in the Gams Formation holding the economic units of the deposit. Microscopic petrography revealed that most of primary textures have been overprinted by recrystallization, alteration, replacement and deformational textures produced during the polyphase metamorphism of the Namaquan Orogeny. Therefore, EPMA analysis provided the bulk of information to define the geochemical distribution of sphalerite. A lateral variation was noticed throughout the Gams Formation, whereby the North orebody presents Zn-rich and Fe+Mn-poor sphalerite while the West and East orebodies contain Zn-poor and Fe-Mn-rich sphalerite. This feature has been interpreted as the association of a chemocline and a variation in the basin topography defining deep Mn+Fe-rich zones and shallow Mn+Fe-poor zones in the primitive basin. It is suggested that mineralized hot brines mixed with seawater developed the chemocline. The uneven topography shaped the geochemical variation between the actual orebodies.
- Full Text:
- Date Issued: 2018
- Authors: Poignant-Molina, Léo
- Date: 2018
- Subjects: Sphalerite , Sphalerite South Africa Gamsberg , Manganese South Africa Gamsberg , Zinc mines and mining South Africa Gamsberg , Geochemistry South Africa Gamsberg , Metamorphism (Geology) , Electron probe microanalysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63775 , vital:28488
- Description: The Gamsberg deposit is a 200 Mt zinc reserve belonging to the world class base metalrich Aggeneys-Gamsberg mining district. A rifting environment permitted the development of four proximal SEDEX-type deposits whereby Gamsberg is localized in the eastern side of the district and characterised by a peculiar enrichment in manganese. This study investigates the geochemistry of sphalerite in the Gams Formation holding the economic units of the deposit. Microscopic petrography revealed that most of primary textures have been overprinted by recrystallization, alteration, replacement and deformational textures produced during the polyphase metamorphism of the Namaquan Orogeny. Therefore, EPMA analysis provided the bulk of information to define the geochemical distribution of sphalerite. A lateral variation was noticed throughout the Gams Formation, whereby the North orebody presents Zn-rich and Fe+Mn-poor sphalerite while the West and East orebodies contain Zn-poor and Fe-Mn-rich sphalerite. This feature has been interpreted as the association of a chemocline and a variation in the basin topography defining deep Mn+Fe-rich zones and shallow Mn+Fe-poor zones in the primitive basin. It is suggested that mineralized hot brines mixed with seawater developed the chemocline. The uneven topography shaped the geochemical variation between the actual orebodies.
- Full Text:
- Date Issued: 2018
Occurrence of mugilid and sparid fishes in Zostera capensis and bare sediment habitats of the Knysna Estuary
- Authors: Pollard, Melissa
- Date: 2018
- Subjects: Gray mullets South Africa Knysna Lagoon , Sparidae South Africa Knysna Lagoon , Seagrasses South Africa Knysna Lagoon , Eelgrass South Africa Knysna Lagoon , Gray mullets Habitat South Africa Knysna Lagoon , Sparidae Habitat South Africa Knysna Lagoon , Underwater videography in wildlife monitoring , Seining , Zostera capensis Setchel
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54979 , vital:26641
- Description: Seagrass meadows are regarded as one of the most unique and valuable ecosystems in the biosphere, primarily because of the variety of services that they provide. Seagrass meadows serve as nursery grounds for many species and often play an important role in the juvenile stages of economically and recreationally important fish. Zostera capensis Setchell is one of the most dominant submerged macrophytes and the most common seagrass in South African estuaries and is often referred to as eelgrass. Zostera capensis meadows occupy a large area within the Knysna Estuary but little is known about their importance to associated fish assemblages. With Z. capensis meadows being under increased pressure from anthropogenic influences, it is important to establish which fish species and families utilize these habitats and what role they play in the ecology of fish assemblages within the Knysna Estuary. The primary objective of this study was to compare the use of Z. capensis and adjacent bare sediment areas by mainly large juvenile and subadult sparids and mugilids using different techniques. The two main hypotheses were as follows; 1) Mugilidae are likely to be more dominant in the unvegetated areas of the estuary littoral and Sparidae are likely to predominate within the Z. capensis bed areas of the estuary littoral. 2) The non-destructive underwater video monitoring method would yield similar fish composition data to seine netting sampling of the identical sites. Both hypotheses were assessed using data collected during this study and the analysis of historical unpublished data. Overall, Mugilidae were more abundant at bare unvegetated areas where they did most of their foraging. Sparidae were more abundant in the Z. capensis beds, which was also the habitat where they primarily foraged. With regards to the comparison of two different sampling methods, namely underwater video monitoring and seine netting, similar patterns arose with regards to the fish species observed in camera footage and those captured in the seine net, although the abundances were not always comparable.
- Full Text:
- Date Issued: 2018
- Authors: Pollard, Melissa
- Date: 2018
- Subjects: Gray mullets South Africa Knysna Lagoon , Sparidae South Africa Knysna Lagoon , Seagrasses South Africa Knysna Lagoon , Eelgrass South Africa Knysna Lagoon , Gray mullets Habitat South Africa Knysna Lagoon , Sparidae Habitat South Africa Knysna Lagoon , Underwater videography in wildlife monitoring , Seining , Zostera capensis Setchel
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54979 , vital:26641
- Description: Seagrass meadows are regarded as one of the most unique and valuable ecosystems in the biosphere, primarily because of the variety of services that they provide. Seagrass meadows serve as nursery grounds for many species and often play an important role in the juvenile stages of economically and recreationally important fish. Zostera capensis Setchell is one of the most dominant submerged macrophytes and the most common seagrass in South African estuaries and is often referred to as eelgrass. Zostera capensis meadows occupy a large area within the Knysna Estuary but little is known about their importance to associated fish assemblages. With Z. capensis meadows being under increased pressure from anthropogenic influences, it is important to establish which fish species and families utilize these habitats and what role they play in the ecology of fish assemblages within the Knysna Estuary. The primary objective of this study was to compare the use of Z. capensis and adjacent bare sediment areas by mainly large juvenile and subadult sparids and mugilids using different techniques. The two main hypotheses were as follows; 1) Mugilidae are likely to be more dominant in the unvegetated areas of the estuary littoral and Sparidae are likely to predominate within the Z. capensis bed areas of the estuary littoral. 2) The non-destructive underwater video monitoring method would yield similar fish composition data to seine netting sampling of the identical sites. Both hypotheses were assessed using data collected during this study and the analysis of historical unpublished data. Overall, Mugilidae were more abundant at bare unvegetated areas where they did most of their foraging. Sparidae were more abundant in the Z. capensis beds, which was also the habitat where they primarily foraged. With regards to the comparison of two different sampling methods, namely underwater video monitoring and seine netting, similar patterns arose with regards to the fish species observed in camera footage and those captured in the seine net, although the abundances were not always comparable.
- Full Text:
- Date Issued: 2018
Subjective measurements of persistence of time series
- Authors: Poswayo, Sihle
- Date: 2018
- Subjects: Time-series analysis , Space and time Time -- Philosophy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34372 , vital:33361
- Description: In this paper we suggest the use of subjective judgements to measure persistence in time series by comparing pairs of graphs with different Hurst exponents. The group of respondents consisted of 40 volunteers who were asked to identify the more jagged out of two graphs presented to them (that is, less persistent). The respondents were approached as a group and requested to work independently in the completion of ques- tionnaires administered to them. The respondents were supervised by the researchers. The graphs were simulated using time series package of Mathematica R [26]. The re- sponses were processed using an algorithm based on the Thurstone-Mosteller model for paired comparisons [29]. The results of the analysis show that the human eye is capable of distinguishing graphs of time series with Hurst exponent difference as small as only 0.02.
- Full Text:
- Date Issued: 2018
- Authors: Poswayo, Sihle
- Date: 2018
- Subjects: Time-series analysis , Space and time Time -- Philosophy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34372 , vital:33361
- Description: In this paper we suggest the use of subjective judgements to measure persistence in time series by comparing pairs of graphs with different Hurst exponents. The group of respondents consisted of 40 volunteers who were asked to identify the more jagged out of two graphs presented to them (that is, less persistent). The respondents were approached as a group and requested to work independently in the completion of ques- tionnaires administered to them. The respondents were supervised by the researchers. The graphs were simulated using time series package of Mathematica R [26]. The re- sponses were processed using an algorithm based on the Thurstone-Mosteller model for paired comparisons [29]. The results of the analysis show that the human eye is capable of distinguishing graphs of time series with Hurst exponent difference as small as only 0.02.
- Full Text:
- Date Issued: 2018
Regional and community food systems for rural households :|bthe case of maize in Mqanduli, Eastern Cape Province, South Africa
- Authors: Qangule, Mondli
- Date: 2018
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Agricultural systems -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10232 , vital:35383
- Description: Smallholder farmers have been growing food in their communities, but some are still food insecure. Therefore, appropriate food systems are very important for smallholder farmers’ self-reliance as well as food and nutrition security. The study focuses only on community and regional maize food systems for rural households. The main aim of this study was to investigate the regional and community food systems for smallholder maize farmers in Mqanduli. The objectives of the study were to profile smallholder maize farmers, describing the existing maize food systems and patterns in Mqanduli and also to determine factors that influence farmers’ participation in local or regional markets. Availability or convenient sampling and random sampling techniques were used to collect primary data from smallholder maize farmers. Descriptive statistics was used to profile smallholder farmers, as well as, in describing the existing maize food systems at Mqanduli. The binary logistic regression model was used to analyse the variables that had influenced the smallholder famers’ participation in markets. Descriptive results revealed that, smallholder maize farmers in Mqanduli are characterised by high participation in both local and regional markets. Moreover, they utilized both community and regional food systems. Logistic regression results indicated that, out of 11 variables included in the analysis as factors influencing farmers’ participation, 6 of them (age, level of education, market information, distance, access to credit and extension visit) were found to be significant and 5 (gender, amount of land, transport availability etc) were not significant. However, access to credit and distance were found to be the most significant variables, showing a positive relationship to smallholder maize producer`s market participation. Therefore, it was recommended that, there must be more investment in research by government and policy makers when it comes to food systems especially in rural areas, to enhance smallholders’ livelihood. More access to credit is also needed by farmers in order to be able to market their produces.
- Full Text:
- Date Issued: 2018
- Authors: Qangule, Mondli
- Date: 2018
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Agricultural systems -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10232 , vital:35383
- Description: Smallholder farmers have been growing food in their communities, but some are still food insecure. Therefore, appropriate food systems are very important for smallholder farmers’ self-reliance as well as food and nutrition security. The study focuses only on community and regional maize food systems for rural households. The main aim of this study was to investigate the regional and community food systems for smallholder maize farmers in Mqanduli. The objectives of the study were to profile smallholder maize farmers, describing the existing maize food systems and patterns in Mqanduli and also to determine factors that influence farmers’ participation in local or regional markets. Availability or convenient sampling and random sampling techniques were used to collect primary data from smallholder maize farmers. Descriptive statistics was used to profile smallholder farmers, as well as, in describing the existing maize food systems at Mqanduli. The binary logistic regression model was used to analyse the variables that had influenced the smallholder famers’ participation in markets. Descriptive results revealed that, smallholder maize farmers in Mqanduli are characterised by high participation in both local and regional markets. Moreover, they utilized both community and regional food systems. Logistic regression results indicated that, out of 11 variables included in the analysis as factors influencing farmers’ participation, 6 of them (age, level of education, market information, distance, access to credit and extension visit) were found to be significant and 5 (gender, amount of land, transport availability etc) were not significant. However, access to credit and distance were found to be the most significant variables, showing a positive relationship to smallholder maize producer`s market participation. Therefore, it was recommended that, there must be more investment in research by government and policy makers when it comes to food systems especially in rural areas, to enhance smallholders’ livelihood. More access to credit is also needed by farmers in order to be able to market their produces.
- Full Text:
- Date Issued: 2018