Mineralogy and geochemistry of permian black shales and carbonate concretions in the lower ECCA formations of the Steytlerville- Jansenville area, southern Karoo basin
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
Modelling the structure and interactions of leukocyte integrins
- Authors: Dawson, Kyle-Richard
- Date: 2019
- Subjects: Proteins -- Structure , Molecular immunology Biochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39392 , vital:35239
- Description: Heterodimeric transmembrane protein structure is complex and insufficient structural information exists, concerning leukocyte integrin proteins. To determine protein structure, homology modelling was conducted and modelling software was evaluated. Leukocyte integrin homologs were obtained from the PDB and models were generated using online servers and MODELLER. Template homologs were fewer in number and of lower quality in comparison to monomeric extracellular proteins. Models were docked using ClusPro, HADDOCK2.2 and AutoDock vina. Models were evaluated using PROSA, Verify-3D and PROSESS. Higher quality models were generated when using MODELLER to separately model monomeric subunits in three defined domain regions (extracellular, transmembrane and cytoplasmic). Template selection concerning these proteins is critical as an intricate relationship exists between model quality, template quality, template quantity, template resolution, target-template identity and template sequence coverage. Docking monomeric subunits was challenging when using ClusPro and the best ligand docking procedures were completed using AutoDock vina. PROSESS provided the most accurate evaluation of protein models, in comparison to PROSA and Verify-3D. These results indicate that although homology modelling is a powerful tool there is much room for improvement. Experimentally obtained templates should be expanded upon within the PDB and energy functions should cater for both monomeric and transmembrane heterodimeric proteins. Leukocyte integrins appear to adopt a closed conformation, which may still facilitate LDV ligand association within the α/β interface. The α3β1 integrin may interact with laminin-5 through the ELV sequence within the G-domain of the α laminin subunit
- Full Text:
- Date Issued: 2019
- Authors: Dawson, Kyle-Richard
- Date: 2019
- Subjects: Proteins -- Structure , Molecular immunology Biochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39392 , vital:35239
- Description: Heterodimeric transmembrane protein structure is complex and insufficient structural information exists, concerning leukocyte integrin proteins. To determine protein structure, homology modelling was conducted and modelling software was evaluated. Leukocyte integrin homologs were obtained from the PDB and models were generated using online servers and MODELLER. Template homologs were fewer in number and of lower quality in comparison to monomeric extracellular proteins. Models were docked using ClusPro, HADDOCK2.2 and AutoDock vina. Models were evaluated using PROSA, Verify-3D and PROSESS. Higher quality models were generated when using MODELLER to separately model monomeric subunits in three defined domain regions (extracellular, transmembrane and cytoplasmic). Template selection concerning these proteins is critical as an intricate relationship exists between model quality, template quality, template quantity, template resolution, target-template identity and template sequence coverage. Docking monomeric subunits was challenging when using ClusPro and the best ligand docking procedures were completed using AutoDock vina. PROSESS provided the most accurate evaluation of protein models, in comparison to PROSA and Verify-3D. These results indicate that although homology modelling is a powerful tool there is much room for improvement. Experimentally obtained templates should be expanded upon within the PDB and energy functions should cater for both monomeric and transmembrane heterodimeric proteins. Leukocyte integrins appear to adopt a closed conformation, which may still facilitate LDV ligand association within the α/β interface. The α3β1 integrin may interact with laminin-5 through the ELV sequence within the G-domain of the α laminin subunit
- Full Text:
- Date Issued: 2019
Modernisation and extension of InetVis: a network security data visualisation tool
- Authors: Johnson, Yestin
- Date: 2019
- Subjects: Data visualization , InetVis (Application software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69223 , vital:29447
- Description: This research undertook an investigation in digital archaeology, modernisation, and revitalisation of the InetVis software application, developed at Rhodes University in 2007. InetVis allows users to visualise network traffic in an interactive 3D scatter plot. This software is based on the idea of the Spinning Cube of Potential Doom, introduced by Stephen Lau. The original InetVis research project aimed to extend this concept and implementation, specifically for use in analysing network telescope traffic. The InetVis source code was examined and ported to run on modern operating systems. The porting process involved updating the UI framework, Qt, from version 3 to 5, as well as adding support for 64-bit compilation. This research extended its usefulness with the implementation of new, high-value, features and improvements. The most notable new features include the addition of a general settings framework, improved screenshot generation, automated visualisation modes, new keyboard shortcuts, and support for building and running InetVis on macOS. Additional features and improvements were identified for future work. These consist of support for a plug-in architecture and an extended heads-up display. A user survey was then conducted, determining that respondents found InetVis to be easy to use and useful. The user survey also allowed the identification of new and proposed features that the respondents found to be most useful. At this point, no other tool offers the simplicity and user-friendliness of InetVis when it comes to the analysis of network packet captures, especially those from network telescopes.
- Full Text:
- Date Issued: 2019
- Authors: Johnson, Yestin
- Date: 2019
- Subjects: Data visualization , InetVis (Application software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69223 , vital:29447
- Description: This research undertook an investigation in digital archaeology, modernisation, and revitalisation of the InetVis software application, developed at Rhodes University in 2007. InetVis allows users to visualise network traffic in an interactive 3D scatter plot. This software is based on the idea of the Spinning Cube of Potential Doom, introduced by Stephen Lau. The original InetVis research project aimed to extend this concept and implementation, specifically for use in analysing network telescope traffic. The InetVis source code was examined and ported to run on modern operating systems. The porting process involved updating the UI framework, Qt, from version 3 to 5, as well as adding support for 64-bit compilation. This research extended its usefulness with the implementation of new, high-value, features and improvements. The most notable new features include the addition of a general settings framework, improved screenshot generation, automated visualisation modes, new keyboard shortcuts, and support for building and running InetVis on macOS. Additional features and improvements were identified for future work. These consist of support for a plug-in architecture and an extended heads-up display. A user survey was then conducted, determining that respondents found InetVis to be easy to use and useful. The user survey also allowed the identification of new and proposed features that the respondents found to be most useful. At this point, no other tool offers the simplicity and user-friendliness of InetVis when it comes to the analysis of network packet captures, especially those from network telescopes.
- Full Text:
- Date Issued: 2019
New synergic biomaterials for anti-cancer therapy
- Authors: Swanepoel, Bresler
- Date: 2019
- Subjects: Pharmaceutical chemistry , Cancer -- Research , Biomedical materials
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43957 , vital:37087
- Description: In the last two decades, anti-cancer therapy has grown considerably with the help of both natural and synthetic anti-cancer compounds but, the search for new and improved cancer treatment remains an ongoing and important issue. Some anti-cancer compounds such as cisplatin are limited by their toxicity in normal tissues and the development of drug resistance. Therefore, in order to address drug resistance and side-effects of anti-cancer agents, recent research has been focusing on finding novel combinations of anti-cancer agents that have non-overlapping mechanisms of action. The first objective of this study was to determine the mechanism of action of Anemone nemorosa, Artemisia afra, N-[[3-(4-bromophenyl)-1H-pyrazol-5-yl]-carbamothioyl]-4-chloro-benzamide (BC-7) and N-benzoyl-N’-(3-(4-bromophenyl)-1H-pyrazol-5-yl)-thiourea (BT-7) through cell cycle arrest, phosphatidylserine translocation (PS), caspase activation and mitochondrial membrane depolarization. This study has shown that A. nemorosa, BC-7 and A. afra are capable of inducing cell death within three cancer cell lines namely HeLa, MeWo and HepG2, at varying degrees. HeLa cells were the most susceptible to treatment with A. nemorosa and BC-7 with IC50 values of 20.33 ± 2.480 μg/ml and 65.58 ± 8.400 μM (28.58 ± 3.660 μg/ml), respectively. A. afra was the most active against HepG2 cells with an IC50 value of 37.55 μg/ml. BT-7 was not cytotoxic against any of the cancer cell lines. The effects on HeLa cells and their progression through the cell cycle indicated that cells were arrested in the early M phase for all treatments. The induction of apoptosis was confirmed by an increase in PS translocation and activation of caspase 3 and 8 as well as a decrease in the mitochondrial membrane potential. It was deduced that A. nemorosa, A. afra and BC-7 induce caspase-dependent apoptosis in a mitochondrial dependent manner. The second objective of this study was to investigate the potential of A. nemorosa, A. afra and BC-7 to target various mediators involved in the inflammatory response as an alternative method in which cell death may be induced. Most treatments indicated that a tumour-elicited inflammatory response is indeed induced in HeLa cells and that the significant activation of nuclear factor kappa B (NF-κB) favoured the production of nitric oxide (NO) over cyclo-oxygenase 2 (COX-2). However, treatments with A. nemorosa, BC-7 and A. afra at their IC10 showed the potential of inhibiting this response. ROS levels were increased by most treatments and support the idea of ROS-mediated apoptosis. The third objective was to investigate combination treatments of these extracts and compounds for their potential synergistic cytotoxic activity and thus formulating the combinations as potential anti-cancer agents. Thirty combination mixtures were prepared using the IC50 values of each extract or compound at ratios of 1:3, 1:2, 1:1, 2:1 and 3:1, respectively. The cytotoxic/anti-proliferative activity of each mixture was determined by the bisBenzamide H 33342 trihydrochloride/propidium iodide (Hoechst 33342/PI) dual staining method on HeLa cervical cancer cells. The combination index (CI) values, at inhibition of 50% of HeLa cell growth, for each combination mixture, were determined by means of the Chou and Talalay method. The combined effect can then be indicated as CI < 1, synergism; CI = 1, additive effect or CI > 1, antagonism, respectively. Most combination treatments showed to have an antagonistic effect except for cisplatin:BC-7 (1:3, 1:1, 2:1, 3:1) and cisplatin:A. afra (1:3, 1:2, 1:1, 3:1) combinations that showed synergism. The 1:2 ratio of cisplatin:BC-7 and the 2:1 ratio of cisplatin:A. afra were additive. CI values were also calculated at inhibition of 10, 25 and 75% of HeLa cell growth, for each combination mixture. Antagonistic effects were frequently observed at lower effect levels such as at 10 and 25% inhibition of growth. However, this was not seen for the cisplatin:BC-7 combinations as all the ratios indicated synergism. Some of these ratios, such as the 1:3 and 1:2, even led to a greater degree of synergism being obtained, with noticeable antagonistic effects seen at 50 and 75% inhibition of growth. The current finding is that BC-7 and A. afra could lower the dose of cisplatin in combination to achieve a similar anti-cancer efficacy compared to the higher cisplatin dose when used alone. The lower dosage in combination could result in reduced drug resistance as well as limit the toxicity on normal cells associated with cisplatin treatment. In conclusion, this study shows, for the first time, that A. nemorosa has the potential to induce apoptosis and also has some anti- and pro-inflammatory activity in HeLa cancer cells. This study also enhanced the knowledge of the mechanism of apoptosis induction of BC-7, in a more detailed manner, as well as investigated its inflammatory effects for the first time. Results obtained for A. afra correlated nicely to previously reported studies and confirmed that the methods used in this study, although different, leads to the same conclusions. Combination treatments also indicated, for the first time, that BC-7 and A. afra have the ability to function in a synergic manner with cisplatin and proves that, although extensive research may have been done on a plant or compound, more can be discovered. This new information can lead to identification of new compounds in the plants and the integration of signalling pathways that can be targeted for treatment of cancer.
- Full Text:
- Date Issued: 2019
- Authors: Swanepoel, Bresler
- Date: 2019
- Subjects: Pharmaceutical chemistry , Cancer -- Research , Biomedical materials
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43957 , vital:37087
- Description: In the last two decades, anti-cancer therapy has grown considerably with the help of both natural and synthetic anti-cancer compounds but, the search for new and improved cancer treatment remains an ongoing and important issue. Some anti-cancer compounds such as cisplatin are limited by their toxicity in normal tissues and the development of drug resistance. Therefore, in order to address drug resistance and side-effects of anti-cancer agents, recent research has been focusing on finding novel combinations of anti-cancer agents that have non-overlapping mechanisms of action. The first objective of this study was to determine the mechanism of action of Anemone nemorosa, Artemisia afra, N-[[3-(4-bromophenyl)-1H-pyrazol-5-yl]-carbamothioyl]-4-chloro-benzamide (BC-7) and N-benzoyl-N’-(3-(4-bromophenyl)-1H-pyrazol-5-yl)-thiourea (BT-7) through cell cycle arrest, phosphatidylserine translocation (PS), caspase activation and mitochondrial membrane depolarization. This study has shown that A. nemorosa, BC-7 and A. afra are capable of inducing cell death within three cancer cell lines namely HeLa, MeWo and HepG2, at varying degrees. HeLa cells were the most susceptible to treatment with A. nemorosa and BC-7 with IC50 values of 20.33 ± 2.480 μg/ml and 65.58 ± 8.400 μM (28.58 ± 3.660 μg/ml), respectively. A. afra was the most active against HepG2 cells with an IC50 value of 37.55 μg/ml. BT-7 was not cytotoxic against any of the cancer cell lines. The effects on HeLa cells and their progression through the cell cycle indicated that cells were arrested in the early M phase for all treatments. The induction of apoptosis was confirmed by an increase in PS translocation and activation of caspase 3 and 8 as well as a decrease in the mitochondrial membrane potential. It was deduced that A. nemorosa, A. afra and BC-7 induce caspase-dependent apoptosis in a mitochondrial dependent manner. The second objective of this study was to investigate the potential of A. nemorosa, A. afra and BC-7 to target various mediators involved in the inflammatory response as an alternative method in which cell death may be induced. Most treatments indicated that a tumour-elicited inflammatory response is indeed induced in HeLa cells and that the significant activation of nuclear factor kappa B (NF-κB) favoured the production of nitric oxide (NO) over cyclo-oxygenase 2 (COX-2). However, treatments with A. nemorosa, BC-7 and A. afra at their IC10 showed the potential of inhibiting this response. ROS levels were increased by most treatments and support the idea of ROS-mediated apoptosis. The third objective was to investigate combination treatments of these extracts and compounds for their potential synergistic cytotoxic activity and thus formulating the combinations as potential anti-cancer agents. Thirty combination mixtures were prepared using the IC50 values of each extract or compound at ratios of 1:3, 1:2, 1:1, 2:1 and 3:1, respectively. The cytotoxic/anti-proliferative activity of each mixture was determined by the bisBenzamide H 33342 trihydrochloride/propidium iodide (Hoechst 33342/PI) dual staining method on HeLa cervical cancer cells. The combination index (CI) values, at inhibition of 50% of HeLa cell growth, for each combination mixture, were determined by means of the Chou and Talalay method. The combined effect can then be indicated as CI < 1, synergism; CI = 1, additive effect or CI > 1, antagonism, respectively. Most combination treatments showed to have an antagonistic effect except for cisplatin:BC-7 (1:3, 1:1, 2:1, 3:1) and cisplatin:A. afra (1:3, 1:2, 1:1, 3:1) combinations that showed synergism. The 1:2 ratio of cisplatin:BC-7 and the 2:1 ratio of cisplatin:A. afra were additive. CI values were also calculated at inhibition of 10, 25 and 75% of HeLa cell growth, for each combination mixture. Antagonistic effects were frequently observed at lower effect levels such as at 10 and 25% inhibition of growth. However, this was not seen for the cisplatin:BC-7 combinations as all the ratios indicated synergism. Some of these ratios, such as the 1:3 and 1:2, even led to a greater degree of synergism being obtained, with noticeable antagonistic effects seen at 50 and 75% inhibition of growth. The current finding is that BC-7 and A. afra could lower the dose of cisplatin in combination to achieve a similar anti-cancer efficacy compared to the higher cisplatin dose when used alone. The lower dosage in combination could result in reduced drug resistance as well as limit the toxicity on normal cells associated with cisplatin treatment. In conclusion, this study shows, for the first time, that A. nemorosa has the potential to induce apoptosis and also has some anti- and pro-inflammatory activity in HeLa cancer cells. This study also enhanced the knowledge of the mechanism of apoptosis induction of BC-7, in a more detailed manner, as well as investigated its inflammatory effects for the first time. Results obtained for A. afra correlated nicely to previously reported studies and confirmed that the methods used in this study, although different, leads to the same conclusions. Combination treatments also indicated, for the first time, that BC-7 and A. afra have the ability to function in a synergic manner with cisplatin and proves that, although extensive research may have been done on a plant or compound, more can be discovered. This new information can lead to identification of new compounds in the plants and the integration of signalling pathways that can be targeted for treatment of cancer.
- Full Text:
- Date Issued: 2019
Novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine: an investigation of their inclusion ability
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
Nutritional and pharmacological profile of moringa oleifera lam. Leaves cultivated in the South African ecotype
- Authors: Yako, Zomsa
- Date: 2019
- Subjects: Moringa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14605 , vital:40021
- Description: Moringa oleifera Lam. is native to the Indian ecotype, which has become naturalized in many tropic and subtropic regions worldwide, thus a great variation in the bioactive compounds of the plant is recorded. The introduction of Moringa oleifera to South Africa occurred in the turn of the twentieth century with the aim of combating malnourishment, aiding health and fostering economic development. Therefore, this study was conducted with the aim of evaluating and authenticating the nutritional parameters, essential oil and bioactive components found in the various solvent extracts of Moringa oleifera leaves cultivated in the South African ecotype. It also elucidated some of the plants medicinal properties by investigating the antioxidant and antibacterial properties of the plant. The essential oil of the leaves was extracted using two methods (solvent free microwave extraction and hydrodistillation) and analysed using Gas Chromotography/Mass Spectrometer. The safety profile of the leaves was investigated using brine shrimp model. The results from the study revealed that Moringa oleifera leaves cultivated in South Africa were rich in crude protein levels (28.72%) and carbohydrate (28.84%). Among the minerals tested for, the leaves contained high content of calcium (1603.33 mg/100 g), potassium (1690 mg/100 g), zinc (13.03 mg/100 g) and iron (21.13 mg/100 g). The vitamin E content had the highest concentration (89.43 mg/100 g) among the vitamins evaluated. The leaves of Moringa oleifera had low quantities of antinutrients in relation to minerals, thus ensuring nutrients availability. This study identified 15 fatty acids in the dried leaves of Moringa. The highest fatty acid detected were polyunsaturated fatty acids, linoleic acid (56.36) and alpha-linolenic acid (687.58), 7 of the fatty acids were saturated fatty acids, though relatively low besides stearic acid. 15 amino acids were present, 7 of which were essential amino acids, namely; threonine, tyrosine, methionine, valine, phenylalanine, isoleucine and leucine. vi Among the phytochemicals evaluated, the aqueous extract gave the highest total phenolic content (21.01 ± 2.315 mg GAE/g), the acetone extract gave the highest proanthocyanidin (15.33 3.5 mg CE/g) and flavonoid contents (25.04±3.28 mg QE/g), while saponin and alkaloid contents were 27.73 ± 9.97% and 7.32 ± 2.73 % respectively. All the extracts exhibited high radical scavenging power against the 2,2- diphenyl-1-picrylhydrazyl radical with an IC50 less than 0.025 mg/mL. Aqueous extract gave the highest capacity based on ABTS and TAC assays with IC50 of 0.074 mg/ mL and 0.055 mg/mL respectively. Ethanol extract exhibited the least antioxidant capacity among the extracts, as well as the least antimicrobial activity on both Gram −ve and Gram +ve bacteria with all its minimum inhibitory concentration values greater than 5 mg/mL. The acetone extract exhibited the strongest antimicrobial activity among the extracts. A total of 8 and 24 chemical compounds were found from the solvent-free microwave extracted and hydrodistilled oils, respectively. The major components found from hydrodistillation were 2-Hexanal (16.37%), Nonanal (6.09%), 5 9-undecadien-2-one 6, 10 dimethyl- (e) - (8.01%), trans-beta-Ionone (8.02%) and octadecane (9.67%). For the solvent free microwave extracted oil, Benzene acetaldehyde (5.68%), Octadecane, Pentacosane and Eicosane which were 11.03%, were the major components. Toxicity evaluation revealed that mortality was time dependent. As the exposure period increased, mortality kept increasing. The hatching success of the cysts in acetone, aqueous and ethanol extracts were 35.7, 33.6 and 35.2% respectively. Acetone extract showed the most prominent hatching success. Hatchability and lethality were in a concentration dependent fashion. Among the extracts, acetone extract exhibited the highest lethality (12.3%) to the nauplii, followed by ethanol (10.9%), then aqueous (5.6%) extracts. All the results obtained from this study suggest that Moringa has the potential of eradicating malnutrition and aid health. It contains the necessary nutritional and bioactive compounds and the leaves proved not to be toxic at the levels (0.0625 – 1 mg/mL) tested.
- Full Text:
- Date Issued: 2019
- Authors: Yako, Zomsa
- Date: 2019
- Subjects: Moringa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14605 , vital:40021
- Description: Moringa oleifera Lam. is native to the Indian ecotype, which has become naturalized in many tropic and subtropic regions worldwide, thus a great variation in the bioactive compounds of the plant is recorded. The introduction of Moringa oleifera to South Africa occurred in the turn of the twentieth century with the aim of combating malnourishment, aiding health and fostering economic development. Therefore, this study was conducted with the aim of evaluating and authenticating the nutritional parameters, essential oil and bioactive components found in the various solvent extracts of Moringa oleifera leaves cultivated in the South African ecotype. It also elucidated some of the plants medicinal properties by investigating the antioxidant and antibacterial properties of the plant. The essential oil of the leaves was extracted using two methods (solvent free microwave extraction and hydrodistillation) and analysed using Gas Chromotography/Mass Spectrometer. The safety profile of the leaves was investigated using brine shrimp model. The results from the study revealed that Moringa oleifera leaves cultivated in South Africa were rich in crude protein levels (28.72%) and carbohydrate (28.84%). Among the minerals tested for, the leaves contained high content of calcium (1603.33 mg/100 g), potassium (1690 mg/100 g), zinc (13.03 mg/100 g) and iron (21.13 mg/100 g). The vitamin E content had the highest concentration (89.43 mg/100 g) among the vitamins evaluated. The leaves of Moringa oleifera had low quantities of antinutrients in relation to minerals, thus ensuring nutrients availability. This study identified 15 fatty acids in the dried leaves of Moringa. The highest fatty acid detected were polyunsaturated fatty acids, linoleic acid (56.36) and alpha-linolenic acid (687.58), 7 of the fatty acids were saturated fatty acids, though relatively low besides stearic acid. 15 amino acids were present, 7 of which were essential amino acids, namely; threonine, tyrosine, methionine, valine, phenylalanine, isoleucine and leucine. vi Among the phytochemicals evaluated, the aqueous extract gave the highest total phenolic content (21.01 ± 2.315 mg GAE/g), the acetone extract gave the highest proanthocyanidin (15.33 3.5 mg CE/g) and flavonoid contents (25.04±3.28 mg QE/g), while saponin and alkaloid contents were 27.73 ± 9.97% and 7.32 ± 2.73 % respectively. All the extracts exhibited high radical scavenging power against the 2,2- diphenyl-1-picrylhydrazyl radical with an IC50 less than 0.025 mg/mL. Aqueous extract gave the highest capacity based on ABTS and TAC assays with IC50 of 0.074 mg/ mL and 0.055 mg/mL respectively. Ethanol extract exhibited the least antioxidant capacity among the extracts, as well as the least antimicrobial activity on both Gram −ve and Gram +ve bacteria with all its minimum inhibitory concentration values greater than 5 mg/mL. The acetone extract exhibited the strongest antimicrobial activity among the extracts. A total of 8 and 24 chemical compounds were found from the solvent-free microwave extracted and hydrodistilled oils, respectively. The major components found from hydrodistillation were 2-Hexanal (16.37%), Nonanal (6.09%), 5 9-undecadien-2-one 6, 10 dimethyl- (e) - (8.01%), trans-beta-Ionone (8.02%) and octadecane (9.67%). For the solvent free microwave extracted oil, Benzene acetaldehyde (5.68%), Octadecane, Pentacosane and Eicosane which were 11.03%, were the major components. Toxicity evaluation revealed that mortality was time dependent. As the exposure period increased, mortality kept increasing. The hatching success of the cysts in acetone, aqueous and ethanol extracts were 35.7, 33.6 and 35.2% respectively. Acetone extract showed the most prominent hatching success. Hatchability and lethality were in a concentration dependent fashion. Among the extracts, acetone extract exhibited the highest lethality (12.3%) to the nauplii, followed by ethanol (10.9%), then aqueous (5.6%) extracts. All the results obtained from this study suggest that Moringa has the potential of eradicating malnutrition and aid health. It contains the necessary nutritional and bioactive compounds and the leaves proved not to be toxic at the levels (0.0625 – 1 mg/mL) tested.
- Full Text:
- Date Issued: 2019
On the study of the performance of Photovoltaic power plants
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
Perceptions of climate change and adaptation strategies: the case of smallholder farmers of Raymond Mhlaba, Port Saint Johns’ and Ingquza Hill local municipality in the Eastern Cape.
- Authors: Maya, Okuhle
- Date: 2019
- Subjects: Climatic changes Farms, Small
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17271 , vital:40871
- Description: Climate change has become indisputable judging from the observed global variations in precipitation, increases in average temperatures, rising average sea levels and melting of ice. The climate phenomenon has since evolved globally and it has been largely documented by scholars. Because of the increases in global temperatures, weather patterns have also changed. This change has resulted in debates on climate change as well as how to respond to it. Various scholars across the world have expressed their opinions about climate change; its causes, impacts and adaptation. In addition, there has been a growing body of literature and studies focusing on smallholder farmers’ perceptions of climate change. Without a doubt, climate change will and has left a group of people, communities and countries vulnerable. In particular, developing countries and poor communities in sub-Saharan Africa are expected to be affected the most by the impacts of climate change. This is mainly because of the region’s dependence on natural resources and their limited capacity to adapt. Literature further adds that vulnerability is on condition of the community’s socioeconomic characteristics and physical surroundings. Climate change variations pose a threat to the agricultural sector and food security of households relying on subsistence farming for survival. Climate variations such as decrease in rainfall and increased hot seasons have been reported to have led to a decline in food production, death of livestock and outbreaks human and animal diseases. The study’s main aim was to determine the smallholder farmers’ perceptions of climate change and adaptation strategies in Raymond Mhlaba, Port Saint Johns’ and Ingquza Hill local municipalities. Particularly, the study looked at the factors influencing these perceptions and the factors affecting the smallholder farmers’ choice of adaptation strategies used in response to climate change. Investigating perception provides insights into the fundamental drivers of behavioural changes in the face of climate change. On their part, adaptation options are greatly shaped by the nature of an individual’s behaviour. The study was carried out in 3 local municipalities (Raymond Mhlaba, Port St Johns’ and Ingquza Hill) in the Eastern Cape, South Africa. The research design applied in this study was cross sectional design where data are collected at a single point in time. Multistage sampling technique was used in selecting respondents from the local municipalities. Stratification was then done to group farmers according to their vi wards and locations. Lastly, purposive sampling was used to select households and smallholder farmers practising crop and livestock production. A total of 211 smallholder farmers constituted the sample size for the study. A close-ended questionnaire was used to conduct structured interviews of household heads. The study utilized both qualitative and quantitative approach. Data collected were coded and entered in Microsoft Excel and transferred to Statistical Package for Social Scientists (SPSS, version 25) for analyses. Descriptive statistics was used to determine the climate change perceptions of smallholder farmers and also to explore the adaptation strategies used by farmers to cope with the impacts of climate change. The findings were explained using frequencies, means and variances. Multinomial Logistic Regression (MNL) was used to determine the factors affecting the choice of adaptation strategies used by smallholder farmers and the probability that a farmer would choose a particular strategy. The results from the study revealed most of the respondents as being able to identify the perceived changes in climate with the environmental changes that they observed. The respondents perceived climate change as an increase in drought period, increase in average temperatures, decrease and variations in rainfall, shortened growing season, crop failure, pests and diseases. However, most of the smallholder farmers disagreed with the frequency of flood incidences as they have not experienced these in their areas. In terms of responses to these changes in climate, the smallholder farmers have used a number of adaptation strategies to cope. Most of the farmers used crop diversification, organic manure, soil and water conservation practices, while others simply did not adapt and some used all the available adaptation strategies identified in this study. The results from the MNL revealed that occupation, household size and years spent in school (education) generally had a positive influence on the choice of adaptation strategy used by smallholder farmers. On the other hand, age; farming systems and membership of a farmers’ association were negatively affecting the smallholder farmers’ choice of adaptation strategy to use in response to climate change. Much support is needed in terms of disseminating information and knowledge among smallholder farmers about climate change and its adaptation strategies. This can be possible through improving extension services, and providing credit to smallholder farmers
- Full Text:
- Date Issued: 2019
- Authors: Maya, Okuhle
- Date: 2019
- Subjects: Climatic changes Farms, Small
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17271 , vital:40871
- Description: Climate change has become indisputable judging from the observed global variations in precipitation, increases in average temperatures, rising average sea levels and melting of ice. The climate phenomenon has since evolved globally and it has been largely documented by scholars. Because of the increases in global temperatures, weather patterns have also changed. This change has resulted in debates on climate change as well as how to respond to it. Various scholars across the world have expressed their opinions about climate change; its causes, impacts and adaptation. In addition, there has been a growing body of literature and studies focusing on smallholder farmers’ perceptions of climate change. Without a doubt, climate change will and has left a group of people, communities and countries vulnerable. In particular, developing countries and poor communities in sub-Saharan Africa are expected to be affected the most by the impacts of climate change. This is mainly because of the region’s dependence on natural resources and their limited capacity to adapt. Literature further adds that vulnerability is on condition of the community’s socioeconomic characteristics and physical surroundings. Climate change variations pose a threat to the agricultural sector and food security of households relying on subsistence farming for survival. Climate variations such as decrease in rainfall and increased hot seasons have been reported to have led to a decline in food production, death of livestock and outbreaks human and animal diseases. The study’s main aim was to determine the smallholder farmers’ perceptions of climate change and adaptation strategies in Raymond Mhlaba, Port Saint Johns’ and Ingquza Hill local municipalities. Particularly, the study looked at the factors influencing these perceptions and the factors affecting the smallholder farmers’ choice of adaptation strategies used in response to climate change. Investigating perception provides insights into the fundamental drivers of behavioural changes in the face of climate change. On their part, adaptation options are greatly shaped by the nature of an individual’s behaviour. The study was carried out in 3 local municipalities (Raymond Mhlaba, Port St Johns’ and Ingquza Hill) in the Eastern Cape, South Africa. The research design applied in this study was cross sectional design where data are collected at a single point in time. Multistage sampling technique was used in selecting respondents from the local municipalities. Stratification was then done to group farmers according to their vi wards and locations. Lastly, purposive sampling was used to select households and smallholder farmers practising crop and livestock production. A total of 211 smallholder farmers constituted the sample size for the study. A close-ended questionnaire was used to conduct structured interviews of household heads. The study utilized both qualitative and quantitative approach. Data collected were coded and entered in Microsoft Excel and transferred to Statistical Package for Social Scientists (SPSS, version 25) for analyses. Descriptive statistics was used to determine the climate change perceptions of smallholder farmers and also to explore the adaptation strategies used by farmers to cope with the impacts of climate change. The findings were explained using frequencies, means and variances. Multinomial Logistic Regression (MNL) was used to determine the factors affecting the choice of adaptation strategies used by smallholder farmers and the probability that a farmer would choose a particular strategy. The results from the study revealed most of the respondents as being able to identify the perceived changes in climate with the environmental changes that they observed. The respondents perceived climate change as an increase in drought period, increase in average temperatures, decrease and variations in rainfall, shortened growing season, crop failure, pests and diseases. However, most of the smallholder farmers disagreed with the frequency of flood incidences as they have not experienced these in their areas. In terms of responses to these changes in climate, the smallholder farmers have used a number of adaptation strategies to cope. Most of the farmers used crop diversification, organic manure, soil and water conservation practices, while others simply did not adapt and some used all the available adaptation strategies identified in this study. The results from the MNL revealed that occupation, household size and years spent in school (education) generally had a positive influence on the choice of adaptation strategy used by smallholder farmers. On the other hand, age; farming systems and membership of a farmers’ association were negatively affecting the smallholder farmers’ choice of adaptation strategy to use in response to climate change. Much support is needed in terms of disseminating information and knowledge among smallholder farmers about climate change and its adaptation strategies. This can be possible through improving extension services, and providing credit to smallholder farmers
- Full Text:
- Date Issued: 2019
Petrography and geochemistry of the Masoke Iron Formation and its associated ferruginous counterparts, kanye basin Botswana
- Authors: Nkabelane, Ndifelani Oriel
- Date: 2019
- Subjects: Petrology -- South Africa , Geochemistry -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115221 , vital:34101
- Description: A sequence of Transvaal Supergroup sediments extends into southern Botswana beneath Kalahari cover as the Kanye basin, these are known to host billions of tons @ 60>Fe. Masoke Iron Formation (Kanye Basin) which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The Palaeoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa hosts high grade (>60% Fe) hematitic and specularitic iron and manganese mineralisation. It is therefore important to study and record the petrographic, mineralogy and geochemistry of Masoke Iron Formation, compare the results to the much known Kuruman and Griquatown Iron Formations. This study systematically investigate and record the petrography, mineralogy and geochemistry of all Masoke Iron Formation of Taupone Group in the Kanye Basin, which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The further objective is to compare Masoke Iron Formation to the equivalent units in the Transvaal basin and Griqualand basin. In contrast to both Transvaal and Griqualand West Basin the Masoke iron Formation (Kanye Basin) has not been the subject of systematic scientific investigations. The study covers three main areas in the Kanye Basin: Keng Pan Area, Ukwi/Moretlwa hill and Janeng Hill Area. The mineralogy and geochemistry of these areas are presented in this study. Kanye Basin has a potential to host a large iron ore deposit, the geological setting in this area incorporates many of the elements necessary for iron ore formation. These include: banded iron formation (BIF), major unconformities with prolonged periods of weathering, carbonate sequences etc. In addition, several large deposits and mines are known from this area. This area can potentially have both hypogene and supergene enrichment of BIF. In this model, prospectively for new deposits is a function of the following: presence of iron formation units, proximity of mapped Asbestos Hills and Voëlwater BIF, thrust faulting (as indicated by the aero-magnetic interpretation), duplication of the ore horizon by folding, intersection of the BIF by major extensional fault, proximity of Olifantshoek/Waterberg outcrop, Gamagara unconformity, presence of carbonates (dolomites) and thin Kalahari sand cover. Major BIF units in the area of study include: the Masoke Iron Formation, equivalent to Kuruman Formation of the Asbestos Hills Subgroup, the Rooinekke iron formation of the Koegas Subgroup and the Hotazel Formation of the Voëlwater Subgroup. Supergene enrichment of these BIFs may occur wherever they are overlain by a major regional unconformity. The base of the Waterberg and the OlifantshoekSupergroups represent major unconformities in this regional target area. Potential for hypogene deposits is indicated by faulting (preferably extensional) proximal to BIF.
- Full Text:
- Date Issued: 2019
- Authors: Nkabelane, Ndifelani Oriel
- Date: 2019
- Subjects: Petrology -- South Africa , Geochemistry -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115221 , vital:34101
- Description: A sequence of Transvaal Supergroup sediments extends into southern Botswana beneath Kalahari cover as the Kanye basin, these are known to host billions of tons @ 60>Fe. Masoke Iron Formation (Kanye Basin) which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The Palaeoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa hosts high grade (>60% Fe) hematitic and specularitic iron and manganese mineralisation. It is therefore important to study and record the petrographic, mineralogy and geochemistry of Masoke Iron Formation, compare the results to the much known Kuruman and Griquatown Iron Formations. This study systematically investigate and record the petrography, mineralogy and geochemistry of all Masoke Iron Formation of Taupone Group in the Kanye Basin, which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The further objective is to compare Masoke Iron Formation to the equivalent units in the Transvaal basin and Griqualand basin. In contrast to both Transvaal and Griqualand West Basin the Masoke iron Formation (Kanye Basin) has not been the subject of systematic scientific investigations. The study covers three main areas in the Kanye Basin: Keng Pan Area, Ukwi/Moretlwa hill and Janeng Hill Area. The mineralogy and geochemistry of these areas are presented in this study. Kanye Basin has a potential to host a large iron ore deposit, the geological setting in this area incorporates many of the elements necessary for iron ore formation. These include: banded iron formation (BIF), major unconformities with prolonged periods of weathering, carbonate sequences etc. In addition, several large deposits and mines are known from this area. This area can potentially have both hypogene and supergene enrichment of BIF. In this model, prospectively for new deposits is a function of the following: presence of iron formation units, proximity of mapped Asbestos Hills and Voëlwater BIF, thrust faulting (as indicated by the aero-magnetic interpretation), duplication of the ore horizon by folding, intersection of the BIF by major extensional fault, proximity of Olifantshoek/Waterberg outcrop, Gamagara unconformity, presence of carbonates (dolomites) and thin Kalahari sand cover. Major BIF units in the area of study include: the Masoke Iron Formation, equivalent to Kuruman Formation of the Asbestos Hills Subgroup, the Rooinekke iron formation of the Koegas Subgroup and the Hotazel Formation of the Voëlwater Subgroup. Supergene enrichment of these BIFs may occur wherever they are overlain by a major regional unconformity. The base of the Waterberg and the OlifantshoekSupergroups represent major unconformities in this regional target area. Potential for hypogene deposits is indicated by faulting (preferably extensional) proximal to BIF.
- Full Text:
- Date Issued: 2019
Pharmacological Evaluation and Medicinal Potential of Vachellia Karroo (Hayne) Banfi & Galasso Pods traditionally used to treat Sexually Transmitted Diseases in the Eastern Cape, South Africa.
- Authors: Maposa, Sandisiwe
- Date: 2019
- Subjects: Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14583 , vital:40017
- Description: Vachellia karroo is widely used in folk medicine in the Eastern Cape Province South Africa, however, the pods are usually discarded as waste. The current study was conducted to evaluate the phytochemical content and the antioxidant activity of V. karroo pods. The pods were extracted using acetone, distilled water, hexane and methanol. The total phenol, flavonoid, proanthocyanidin, alkaloid and saponin contents of the various extracts were determined spectrometrically and antioxidant activity was evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl (DPPH), 2,2´-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), nitric oxide (NO) radicals, while total antioxidant capacity (TAC) was estimated by the phosphomolybdenum assay. V. karro pods had significant amounts of total phenols, flavonoids and proanthocynadin, although, proanthocynadin was not detected in the aqueous and hexane extracts. Methanol and acetone extracts showed higher phenolic, proanthocynadin and flavonoids contents (52.47 ± 6.82 and 29.31 ± 1.49), (334.8±85.1 and 231.22 ±1.80),(288±4.26 & 208.2±17.7) compared to the aqueous and hexane extracts. The alkaloid and saponin contents were 26.67 and 12.85 % respectively. The IC50 values of the methanol extract for DPPH, ABTS and total antioxidant capacity (TAC) were 0.345, 0.017 and 0.116 mg/mL, respectively. Methanol extract of V. karroo pod showed higher polyphenolic content of all the extracts analysed with corresponding strong free radical scavenging potential. These underutilized pods could serve as a new source of antioxidant compounds which could help in combating various ailments. The great antioxidant activity displayed by V. karroo pods extract supports the therapeutic use of this plant in traditional medicine and are attributed to the phytochemical content.The current information suggests that extracts from Vachellia karroo pods might be a ix cheap potential source of natural antioxidants that could be of great importance for the treatment of free radical related diseases. Furthermore, it makes a case for the utilization of the pods instead of discarding them as waste materials. The evaluation of antimicrobial potential of Vachellia karroo extracts was carried out using agar dilution assay against 8 bacterial strains-4 gram-positive [ Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (OK), Bacillus subtilis KZN, Bacillus cereus, and Streptococcus pyogenes] and 4 gram-negative strains[ Vibrio cholera, Klebsiella pneumonia (ATCC 4352), Pseudomonas aeruginosa (ATCC 19582), Salmonella typhi (OK) ]. Six fungal isolates[ Trichophyton mucoides ATCC 201382, Candida albicans (ATCC 10231), Candida glabatra, Penicillium chrysogenum, Aspergillus fumigatus, Penicillum aurantiogriseum] were usedor antifungal assessment. The methanol extract exhibited broad-spectrum activity, with Gram-positive strains being more sensitive than Gram-negative strains. The extracts also showed great inhibition against Candida albicans the fungal isolate responsible for causing candidiasis in women. Since the pods showed promising antimicrobial activity, they could serve as a cheap source for the treatment and management of these sexually transmitted infections. The brine shrimp toxicity test revealed successful hatching of the cysts was in the order: Aqueous extract> methanol extract> hexane extract> acetone extract. The hatching of nauplii was in a concentration dependent fashion, with hatching success decreasing with increase in concentration of extracts. Lethality of extracts determined based on Meyerʼs index of toxicity, showed that the acetone and hexane extracts of V. karroo were moderately toxic. The results of this study indicated that aqueous and methanolic extracts of Vachellia karroo pods were not toxic, therefore supporting its traditional therapeutic usage. This implies that rather than discard x the pods as is waste as it being currently done, Vachellia karroo pods could be salvaged and processed along with the leaves, thus reducing environmental pollution. Proximate parameters (moisture, ash, crude fibre, crude fat, proteins, and carbohydrate) were evaluated using ALASA methods, and elemental analysis by ICP-OES technique. Nutritional analysis showed that V. karroo pods had low content of crude fat and high content of crude fibre, ash, crude protein, and carbohydrate sufficient to meet the recommended dietary allowances. The pods were rich in major minerals Ca, K, P and Mg, with sufficient amount of trace elements Na, Fe, Zn, and Cu. The outcome of this study suggests that Vachellia karroo pods have good nutritional potentials to support or complement the recommended dietary allowance and could be a cheap source of essential nutrients that could help in ameliorating most nutritional challenges as well as contribute remarkably to the amount of nutrient intake in human and animal diets.
- Full Text:
- Date Issued: 2019
- Authors: Maposa, Sandisiwe
- Date: 2019
- Subjects: Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14583 , vital:40017
- Description: Vachellia karroo is widely used in folk medicine in the Eastern Cape Province South Africa, however, the pods are usually discarded as waste. The current study was conducted to evaluate the phytochemical content and the antioxidant activity of V. karroo pods. The pods were extracted using acetone, distilled water, hexane and methanol. The total phenol, flavonoid, proanthocyanidin, alkaloid and saponin contents of the various extracts were determined spectrometrically and antioxidant activity was evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl (DPPH), 2,2´-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), nitric oxide (NO) radicals, while total antioxidant capacity (TAC) was estimated by the phosphomolybdenum assay. V. karro pods had significant amounts of total phenols, flavonoids and proanthocynadin, although, proanthocynadin was not detected in the aqueous and hexane extracts. Methanol and acetone extracts showed higher phenolic, proanthocynadin and flavonoids contents (52.47 ± 6.82 and 29.31 ± 1.49), (334.8±85.1 and 231.22 ±1.80),(288±4.26 & 208.2±17.7) compared to the aqueous and hexane extracts. The alkaloid and saponin contents were 26.67 and 12.85 % respectively. The IC50 values of the methanol extract for DPPH, ABTS and total antioxidant capacity (TAC) were 0.345, 0.017 and 0.116 mg/mL, respectively. Methanol extract of V. karroo pod showed higher polyphenolic content of all the extracts analysed with corresponding strong free radical scavenging potential. These underutilized pods could serve as a new source of antioxidant compounds which could help in combating various ailments. The great antioxidant activity displayed by V. karroo pods extract supports the therapeutic use of this plant in traditional medicine and are attributed to the phytochemical content.The current information suggests that extracts from Vachellia karroo pods might be a ix cheap potential source of natural antioxidants that could be of great importance for the treatment of free radical related diseases. Furthermore, it makes a case for the utilization of the pods instead of discarding them as waste materials. The evaluation of antimicrobial potential of Vachellia karroo extracts was carried out using agar dilution assay against 8 bacterial strains-4 gram-positive [ Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (OK), Bacillus subtilis KZN, Bacillus cereus, and Streptococcus pyogenes] and 4 gram-negative strains[ Vibrio cholera, Klebsiella pneumonia (ATCC 4352), Pseudomonas aeruginosa (ATCC 19582), Salmonella typhi (OK) ]. Six fungal isolates[ Trichophyton mucoides ATCC 201382, Candida albicans (ATCC 10231), Candida glabatra, Penicillium chrysogenum, Aspergillus fumigatus, Penicillum aurantiogriseum] were usedor antifungal assessment. The methanol extract exhibited broad-spectrum activity, with Gram-positive strains being more sensitive than Gram-negative strains. The extracts also showed great inhibition against Candida albicans the fungal isolate responsible for causing candidiasis in women. Since the pods showed promising antimicrobial activity, they could serve as a cheap source for the treatment and management of these sexually transmitted infections. The brine shrimp toxicity test revealed successful hatching of the cysts was in the order: Aqueous extract> methanol extract> hexane extract> acetone extract. The hatching of nauplii was in a concentration dependent fashion, with hatching success decreasing with increase in concentration of extracts. Lethality of extracts determined based on Meyerʼs index of toxicity, showed that the acetone and hexane extracts of V. karroo were moderately toxic. The results of this study indicated that aqueous and methanolic extracts of Vachellia karroo pods were not toxic, therefore supporting its traditional therapeutic usage. This implies that rather than discard x the pods as is waste as it being currently done, Vachellia karroo pods could be salvaged and processed along with the leaves, thus reducing environmental pollution. Proximate parameters (moisture, ash, crude fibre, crude fat, proteins, and carbohydrate) were evaluated using ALASA methods, and elemental analysis by ICP-OES technique. Nutritional analysis showed that V. karroo pods had low content of crude fat and high content of crude fibre, ash, crude protein, and carbohydrate sufficient to meet the recommended dietary allowances. The pods were rich in major minerals Ca, K, P and Mg, with sufficient amount of trace elements Na, Fe, Zn, and Cu. The outcome of this study suggests that Vachellia karroo pods have good nutritional potentials to support or complement the recommended dietary allowance and could be a cheap source of essential nutrients that could help in ameliorating most nutritional challenges as well as contribute remarkably to the amount of nutrient intake in human and animal diets.
- Full Text:
- Date Issued: 2019
Phase Plane Analysis of Linear Systems in Dynamic Mathematical Models
- Authors: Marange, Simukai Daniel
- Date: 2019
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14715 , vital:40064
- Description: A plethora of dynamic mathematical models exist and to understand and master all of them would be a gargantuan task. The author had, nonetheless, attempted to outline some of the methods used to analyse linear systems in modeling. Systems techniques are fundamental to current research in molecular cell-biology. The systems-approach stands in stark contrast to the historically, reductionist paradigm of molecular biology. Field work can be very dangerous. The main purpose of this study was to come up with the best analysis that would be used without going to the real field and thus saving time, money and risks associated with remote field localities. This research showed that the best analysis depends on the nature of the objectives intended to be solved by the model. Phase plane analysis on linear systems assisted in gaining deeper knowledge on the characteristics of such systems. This work analysed some dynamic models looking at phase planes, bifurcation, sensitivity and stability. The research provided a qualitative analysis of the processes not a numerical analysis.
- Full Text:
- Date Issued: 2019
- Authors: Marange, Simukai Daniel
- Date: 2019
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14715 , vital:40064
- Description: A plethora of dynamic mathematical models exist and to understand and master all of them would be a gargantuan task. The author had, nonetheless, attempted to outline some of the methods used to analyse linear systems in modeling. Systems techniques are fundamental to current research in molecular cell-biology. The systems-approach stands in stark contrast to the historically, reductionist paradigm of molecular biology. Field work can be very dangerous. The main purpose of this study was to come up with the best analysis that would be used without going to the real field and thus saving time, money and risks associated with remote field localities. This research showed that the best analysis depends on the nature of the objectives intended to be solved by the model. Phase plane analysis on linear systems assisted in gaining deeper knowledge on the characteristics of such systems. This work analysed some dynamic models looking at phase planes, bifurcation, sensitivity and stability. The research provided a qualitative analysis of the processes not a numerical analysis.
- Full Text:
- Date Issued: 2019
Photocatalytic treatment of organic and inorganic water pollutants using zinc phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
Photophysicochemical properties and surface-enhanced Raman scattering of phthalocyanine-nanoparticle conjugates
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
Post-release evaluation of Megamelus scutellaris Berg. (hemiptera: delphacidae): a biological control agent of water hyacinth Eichhornia crassipes (Mart.) Solms-Laub (Pontederiaceae) in South Africa
- Authors: Miller, Benjamin Erich
- Date: 2019
- Subjects: Megamelus scutellaris Berg. , Delphacidae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92330 , vital:30710
- Description: Water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) is a free-floating aquatic macrophyte from South America that was introduced to South Africa in the 1900s for its attractive ornamental flowers. The plant was classified as a serious invader in the country in the 1970s, eventually becoming the worst invasive aquatic plant in South Africa. Biological control is widely regarded as the most effective method of managing water hyacinth, as it is ecologically safe, cost-effective, and self-sustaining. To date, nine biological control agents have been released in South Africa against water hyacinth, including eight arthropods and a pathogen. Due to the cumulative effects of highly eutrophic waterbodies, which mitigate the damage caused by biological control, and the cold winters which inhibit the rate of biological control agent population build up, South Africa currently has more biological control agents released on water hyacinth than anywhere else in the world. The need for a cold-tolerant agent that can reproduce and develop quickly, while still being damaging to water hyacinth in eutrophic systems, led to the introduction of the most recently released water hyacinth biological control agent, the planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae), which was initially collected from Argentina. This thesis formed the first post-release evaluation of M. scutellaris since its release in South Africa in 2013. It included a greenhouse experiment to measure the agent’s feeding damage in relation to different nutrient levels and stocking rates, as well as a field component to evaluate both the post-winter recovery of M. scutellaris, and a nationwide survey to measure the establishment of the agent around the country in relation to climate, water quality, and plant health. In the greenhouse experiment, the feeding damage was quantified using measurements of plant growth parameters and chlorophyll fluorometry. It was found that, like other biological control agents of water hyacinth, M. scutellaris was most damaging when released in high numbers on plants grown at medium nutrient levels, and less effective on plants grown at elevated nutrient levels. A water hyacinth infestation on the Kubusi River was selected for the evaluation of the post-winter recovery of M. scutellaris. The Kubusi River is both the first site where M. scutellaris was released, and the coldest site where water hyacinth biological control agents have established successfully in South Africa. Monthly visits tracking seasonal plant health characteristics and agent population densities indicated that the populations of M. scutellaris were impacted most significantly by the season. Low temperatures led to the water hyacinth plants being of poor quality during the winter, which had a subsequent negative effect on the agent populations. The agents could only fully recover by late summer, which meant that the plants were without any significant biological control through the initial phases of the growing season, when they were most vulnerable, and a significant lag-phase occurred between the recovery of the plants and the recovery of the agent population after the winter bottleneck. A survey of all sites where M. scutellaris had been released in South Africa yielded 16 sites where the agents had successfully established, having survived at least one full winter. Among these sites were four sites where the agents were found without them having been released, indicating that they can disperse unaided to new sites. The temperature was a major factor responsible for the success or failure of establishment, with very few agents surviving in the hot areas of South Africa or in areas with a high frost incidence. The density of M. scutellaris was higher in nutrient-rich water, and on plants with more leaves, suggesting that the quality of the plants also contributed to establishment. The results of this thesis showed that M. scutellaris is able to establish successfully in South Africa, and that the agents are capable of causing significant damage to water hyacinth, making it a promising addition to the biological control programme. Novel methods of measuring subtle insect feeding damage in plants and quantifying agent populations are also discussed, along with suggestions for the future implementation of M. scutellaris in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Miller, Benjamin Erich
- Date: 2019
- Subjects: Megamelus scutellaris Berg. , Delphacidae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92330 , vital:30710
- Description: Water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) is a free-floating aquatic macrophyte from South America that was introduced to South Africa in the 1900s for its attractive ornamental flowers. The plant was classified as a serious invader in the country in the 1970s, eventually becoming the worst invasive aquatic plant in South Africa. Biological control is widely regarded as the most effective method of managing water hyacinth, as it is ecologically safe, cost-effective, and self-sustaining. To date, nine biological control agents have been released in South Africa against water hyacinth, including eight arthropods and a pathogen. Due to the cumulative effects of highly eutrophic waterbodies, which mitigate the damage caused by biological control, and the cold winters which inhibit the rate of biological control agent population build up, South Africa currently has more biological control agents released on water hyacinth than anywhere else in the world. The need for a cold-tolerant agent that can reproduce and develop quickly, while still being damaging to water hyacinth in eutrophic systems, led to the introduction of the most recently released water hyacinth biological control agent, the planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae), which was initially collected from Argentina. This thesis formed the first post-release evaluation of M. scutellaris since its release in South Africa in 2013. It included a greenhouse experiment to measure the agent’s feeding damage in relation to different nutrient levels and stocking rates, as well as a field component to evaluate both the post-winter recovery of M. scutellaris, and a nationwide survey to measure the establishment of the agent around the country in relation to climate, water quality, and plant health. In the greenhouse experiment, the feeding damage was quantified using measurements of plant growth parameters and chlorophyll fluorometry. It was found that, like other biological control agents of water hyacinth, M. scutellaris was most damaging when released in high numbers on plants grown at medium nutrient levels, and less effective on plants grown at elevated nutrient levels. A water hyacinth infestation on the Kubusi River was selected for the evaluation of the post-winter recovery of M. scutellaris. The Kubusi River is both the first site where M. scutellaris was released, and the coldest site where water hyacinth biological control agents have established successfully in South Africa. Monthly visits tracking seasonal plant health characteristics and agent population densities indicated that the populations of M. scutellaris were impacted most significantly by the season. Low temperatures led to the water hyacinth plants being of poor quality during the winter, which had a subsequent negative effect on the agent populations. The agents could only fully recover by late summer, which meant that the plants were without any significant biological control through the initial phases of the growing season, when they were most vulnerable, and a significant lag-phase occurred between the recovery of the plants and the recovery of the agent population after the winter bottleneck. A survey of all sites where M. scutellaris had been released in South Africa yielded 16 sites where the agents had successfully established, having survived at least one full winter. Among these sites were four sites where the agents were found without them having been released, indicating that they can disperse unaided to new sites. The temperature was a major factor responsible for the success or failure of establishment, with very few agents surviving in the hot areas of South Africa or in areas with a high frost incidence. The density of M. scutellaris was higher in nutrient-rich water, and on plants with more leaves, suggesting that the quality of the plants also contributed to establishment. The results of this thesis showed that M. scutellaris is able to establish successfully in South Africa, and that the agents are capable of causing significant damage to water hyacinth, making it a promising addition to the biological control programme. Novel methods of measuring subtle insect feeding damage in plants and quantifying agent populations are also discussed, along with suggestions for the future implementation of M. scutellaris in South Africa.
- Full Text:
- Date Issued: 2019
Production potential of lucerne (Medicago sativa) over-sown into kikuyu (Pennisetum clandestinum) based pasture
- Fourie, Ilze, Du Preez, Derek
- Authors: Fourie, Ilze , Du Preez, Derek
- Date: 2019
- Subjects: Alfalfa -- South Africa , Field crops , Agriculture -- South Africa , Botany -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39918 , vital:35510
- Description: Dairy farming in the southern Cape region of South Africa is based on irrigated kikuyu (Pennisetum clandestinum) over-sown with different ryegrass species (Lolium spp.). Although this system can be highly productive, sustainable production of kikuyu is dependent on expensive nitrogen (N) fertiliser inputs and irrigation due to a high water requirement to maintain production. The introduction of lucerne (Medicago sativa) into pasture systems can lower the risk of high input cost and droughts. Lucerne has a high nutritive value, is able to fix atmospheric N, has high water-use efficiency and is adapted to local climatic conditions. The aim of this study was to determine the DM production potential of lucerne cultivars from various dormancy groups when over-sown into an existing kikuyu pasture base on soils that are suitable for lucerne cultivation, without any N fertiliser application. The study was carried out on the Outeniqua Research Farm near George, Western Cape. Two cultivars were selected from each of the four lucerne dormancy groups and sown into an existing kikuyu pasture based on soils suited for lucerne cultivation. Three establishment methods namely glyphosate/planter (Gly/Plant), glyphosate/rotavator (Gly/Rot) and rotavator (Rot) were used. The statistical design was a randomised block design with three replicates. The botanical composition (lucerne-, kikuyu-, clover-, grass- and weed content), growth rate (kg DM ha-1 day-1), total DM production (kg DM ha-1) and DM content of the treatments were determined before every grazing. The nutritional value (CP-, ME-, NDF-, Ca-, and P content) of the treatments was determined seasonally. Establishing lucerne into kikuyu with the glyphosate/rotavator (Gly/Rot) and rotavator (Rot) method yielded an overall higher percentage of established seedlings compared to the glyphosate/planter (Gly/Plant) establishment method. The establishment method used affected the botanical composition. Lucerne established with the Gly/Plant or Gly/Rot establishment method into kikuyu had a higher lucerne content than the Rot establishment method. The seasonal growth rates of the kikuyu-lucerne pasture varied between 14.8 kg DM ha-1 day-1 during winter to 84.1 kg DM ha-1 day-1 during summer. The establishment method and cultivar influenced the seasonal growth rate and total seasonal production. The cultivar WL 711 established with Gly/Plant establishment method had the highest or did not differ significantly from the highest lucerne content, seasonal growth rate and total seasonal production within seasons. The total annual production ranged between 13805 to 19975 kg DM ha-1 year-1 with the Gly/Plant establishment method yielding the highest or did not differ significantly from the highest annual production when compared with the other establishment methods. The botanical composition affects the nutritive value of the kikuyu-lucerne pasture. The ME content of kikuyu and kikuyu-lucerne pasture did not meet the daily ME requirements for a lactating dairy cow to maintain milk production throughout both years. The CP and Ca content decreased as the lucerne content decreased and the kikuyu content increased. The P content of kikuyu-lucerne and kikuyu pasture met the daily P requirement of a lactating dairy cow. The dormancy groups D2 and D5 were the only dormancy groups that could meet the recommended Ca:P ratio for dairy cows over all the seasons. Lucerne can be successfully established into kikuyu with the use of herbicide as part of the establishment method. Kikuyu-lucerne pasture has a higher DM production with an improved quality compared to kikuyu pasture. By establishing lucerne into kikuyu the cost of N fertiliser application could be lowered as no N needs to be applied.
- Full Text:
- Date Issued: 2019
- Authors: Fourie, Ilze , Du Preez, Derek
- Date: 2019
- Subjects: Alfalfa -- South Africa , Field crops , Agriculture -- South Africa , Botany -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39918 , vital:35510
- Description: Dairy farming in the southern Cape region of South Africa is based on irrigated kikuyu (Pennisetum clandestinum) over-sown with different ryegrass species (Lolium spp.). Although this system can be highly productive, sustainable production of kikuyu is dependent on expensive nitrogen (N) fertiliser inputs and irrigation due to a high water requirement to maintain production. The introduction of lucerne (Medicago sativa) into pasture systems can lower the risk of high input cost and droughts. Lucerne has a high nutritive value, is able to fix atmospheric N, has high water-use efficiency and is adapted to local climatic conditions. The aim of this study was to determine the DM production potential of lucerne cultivars from various dormancy groups when over-sown into an existing kikuyu pasture base on soils that are suitable for lucerne cultivation, without any N fertiliser application. The study was carried out on the Outeniqua Research Farm near George, Western Cape. Two cultivars were selected from each of the four lucerne dormancy groups and sown into an existing kikuyu pasture based on soils suited for lucerne cultivation. Three establishment methods namely glyphosate/planter (Gly/Plant), glyphosate/rotavator (Gly/Rot) and rotavator (Rot) were used. The statistical design was a randomised block design with three replicates. The botanical composition (lucerne-, kikuyu-, clover-, grass- and weed content), growth rate (kg DM ha-1 day-1), total DM production (kg DM ha-1) and DM content of the treatments were determined before every grazing. The nutritional value (CP-, ME-, NDF-, Ca-, and P content) of the treatments was determined seasonally. Establishing lucerne into kikuyu with the glyphosate/rotavator (Gly/Rot) and rotavator (Rot) method yielded an overall higher percentage of established seedlings compared to the glyphosate/planter (Gly/Plant) establishment method. The establishment method used affected the botanical composition. Lucerne established with the Gly/Plant or Gly/Rot establishment method into kikuyu had a higher lucerne content than the Rot establishment method. The seasonal growth rates of the kikuyu-lucerne pasture varied between 14.8 kg DM ha-1 day-1 during winter to 84.1 kg DM ha-1 day-1 during summer. The establishment method and cultivar influenced the seasonal growth rate and total seasonal production. The cultivar WL 711 established with Gly/Plant establishment method had the highest or did not differ significantly from the highest lucerne content, seasonal growth rate and total seasonal production within seasons. The total annual production ranged between 13805 to 19975 kg DM ha-1 year-1 with the Gly/Plant establishment method yielding the highest or did not differ significantly from the highest annual production when compared with the other establishment methods. The botanical composition affects the nutritive value of the kikuyu-lucerne pasture. The ME content of kikuyu and kikuyu-lucerne pasture did not meet the daily ME requirements for a lactating dairy cow to maintain milk production throughout both years. The CP and Ca content decreased as the lucerne content decreased and the kikuyu content increased. The P content of kikuyu-lucerne and kikuyu pasture met the daily P requirement of a lactating dairy cow. The dormancy groups D2 and D5 were the only dormancy groups that could meet the recommended Ca:P ratio for dairy cows over all the seasons. Lucerne can be successfully established into kikuyu with the use of herbicide as part of the establishment method. Kikuyu-lucerne pasture has a higher DM production with an improved quality compared to kikuyu pasture. By establishing lucerne into kikuyu the cost of N fertiliser application could be lowered as no N needs to be applied.
- Full Text:
- Date Issued: 2019
Property development: a framework for on-time delivery
- Authors: Mkhwe, Tandokazi Lerato
- Date: 2019
- Subjects: Real estate development -- South Africa , Project management -- South Africa Time management Financial statements -- Standards -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41084 , vital:36294
- Description: Property development is a complex process and is considered to be highly risky. The Global Financial Crisis (GFC) in 2009 had a negative impact on property due to various factors such as: increased interest rates; increase of stricter mortgage bond approvals; the recession and other possible financial regulatory factors. Property development plays a major role in the Gross Domestic Product (GFC)) of global economies worldwide, as well as in South Africa and changes in the supply and demand value of property impacts the performance of the property market. Thus, property development and real estate are one of the largest suppliers of employment. Property development entrepreneurs lack the project management skills to manage projects. In this study the related literature was reviewed and an empirical study was conducted. The empirical study was conducted using a quantitative statistical approach, by distributing research questionnaires to members falling within the sample population. The primary objective of the study was to develop a framework for perceived on-time delivery of property development projects. A descriptive survey was conducted among professionals in the property industry, and property development practitioners within South Africa. The findings suggest that the following variables influence the perceived ontime delivery of property development projects: Delays and disruptions, poor workmanship, PESTEL (political, economic, social, technological, legal and environmental) factors, shortfalls in full mortgage bond approval, town planning regulations, and the prevalence of a project management, framework amongst property developers, real-estate agencies and conveyancers. Furthermore, the following variables were identified in the empirical framework affecting the perceived on-time delivery of property development projects: PESTEL namely; Political Factors, Economical Factors, Social Factors, Technological Factors, Environmental Factors and Legal Factors. This study contributed to the South African property development body of knowledge, by determining the factors influencing the completion of property development projects, and on developing a framework for successful implementation of property development projects.
- Full Text:
- Date Issued: 2019
- Authors: Mkhwe, Tandokazi Lerato
- Date: 2019
- Subjects: Real estate development -- South Africa , Project management -- South Africa Time management Financial statements -- Standards -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41084 , vital:36294
- Description: Property development is a complex process and is considered to be highly risky. The Global Financial Crisis (GFC) in 2009 had a negative impact on property due to various factors such as: increased interest rates; increase of stricter mortgage bond approvals; the recession and other possible financial regulatory factors. Property development plays a major role in the Gross Domestic Product (GFC)) of global economies worldwide, as well as in South Africa and changes in the supply and demand value of property impacts the performance of the property market. Thus, property development and real estate are one of the largest suppliers of employment. Property development entrepreneurs lack the project management skills to manage projects. In this study the related literature was reviewed and an empirical study was conducted. The empirical study was conducted using a quantitative statistical approach, by distributing research questionnaires to members falling within the sample population. The primary objective of the study was to develop a framework for perceived on-time delivery of property development projects. A descriptive survey was conducted among professionals in the property industry, and property development practitioners within South Africa. The findings suggest that the following variables influence the perceived ontime delivery of property development projects: Delays and disruptions, poor workmanship, PESTEL (political, economic, social, technological, legal and environmental) factors, shortfalls in full mortgage bond approval, town planning regulations, and the prevalence of a project management, framework amongst property developers, real-estate agencies and conveyancers. Furthermore, the following variables were identified in the empirical framework affecting the perceived on-time delivery of property development projects: PESTEL namely; Political Factors, Economical Factors, Social Factors, Technological Factors, Environmental Factors and Legal Factors. This study contributed to the South African property development body of knowledge, by determining the factors influencing the completion of property development projects, and on developing a framework for successful implementation of property development projects.
- Full Text:
- Date Issued: 2019
Property price prediction: a model utilising sentiment analysis
- Authors: Botes, Rhys Cameron
- Date: 2019
- Subjects: Natural language processing (Computer science) , Computational linguistics Text processing (Computer science) Social networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/37117 , vital:34119
- Description: The increase in the use of social media has led many researchers and companies to investigate the potential uses of the data that is generated by these social media platforms. This research study investigates how the use of sentiment variables, obtained from the social media platform Twitter, can be used to augment housing transfer data in order to develop a predictive model. The Design Science Research (DSR) methodology was followed, guided by a Social Media Framework. Experimentation was required within the Design Cycle of the DSR methodology, which lead to the adoption of the Experimental Research methodology within this cycle. An initial literature review identified regression models for property price prediction. Through experimentation, Gradient Boosting regression was identified as an optimal regression model for this purpose. Thereafter a review of sentiment analysis models was conducted which resulted in the proposal of a CNN-LSTM model for the classification of Tweets. Initial experimentation conducted with this proposed model resulted in an obtained accuracy comparable to the top performing sentiment analysis models identified. A dataset obtained through SemEval, a series of evaluations of computational semantic analysis systems, was used for this phase. For the final experimentation, The CNN-LSTM model was used to obtain sentiment variables from Tweets that were collected from the Western Cape Province in 2017. This property dataset was augmented with the sentiment variables, after which experimentation was conducted by applying Gradient Boosting regression. The augmentation was done in two ways, either based on suburb pertaining to the property, or to the month in which the property was transferred. The results indicate that a model for Property Price Prediction Utilising Sentiment Analysis demonstrates a small improvement when suburb-based sentiment, obtained from Tweets with a minimum threshold per suburb, is utilised. An important finding was the fact that, when geo-coordinates are removed from the dataset, the sentiment variables replace them in the regression results, producing the same level as accuracy as when the coordinates are included.
- Full Text:
- Date Issued: 2019
- Authors: Botes, Rhys Cameron
- Date: 2019
- Subjects: Natural language processing (Computer science) , Computational linguistics Text processing (Computer science) Social networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/37117 , vital:34119
- Description: The increase in the use of social media has led many researchers and companies to investigate the potential uses of the data that is generated by these social media platforms. This research study investigates how the use of sentiment variables, obtained from the social media platform Twitter, can be used to augment housing transfer data in order to develop a predictive model. The Design Science Research (DSR) methodology was followed, guided by a Social Media Framework. Experimentation was required within the Design Cycle of the DSR methodology, which lead to the adoption of the Experimental Research methodology within this cycle. An initial literature review identified regression models for property price prediction. Through experimentation, Gradient Boosting regression was identified as an optimal regression model for this purpose. Thereafter a review of sentiment analysis models was conducted which resulted in the proposal of a CNN-LSTM model for the classification of Tweets. Initial experimentation conducted with this proposed model resulted in an obtained accuracy comparable to the top performing sentiment analysis models identified. A dataset obtained through SemEval, a series of evaluations of computational semantic analysis systems, was used for this phase. For the final experimentation, The CNN-LSTM model was used to obtain sentiment variables from Tweets that were collected from the Western Cape Province in 2017. This property dataset was augmented with the sentiment variables, after which experimentation was conducted by applying Gradient Boosting regression. The augmentation was done in two ways, either based on suburb pertaining to the property, or to the month in which the property was transferred. The results indicate that a model for Property Price Prediction Utilising Sentiment Analysis demonstrates a small improvement when suburb-based sentiment, obtained from Tweets with a minimum threshold per suburb, is utilised. An important finding was the fact that, when geo-coordinates are removed from the dataset, the sentiment variables replace them in the regression results, producing the same level as accuracy as when the coordinates are included.
- Full Text:
- Date Issued: 2019
Public open spaces in Motherwell NU1-9: accessibility and community perceptions
- Authors: Nkonki, Busisiwe
- Date: 2019
- Subjects: Open spaces -- South Africa -- Port Elizabeth , Urban geography Human geography Land use, Urban Cities and towns
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33397 , vital:32758
- Description: Public Open Spaces (POS) with social, environmental and economic benefits are associated with the enhancement of human settlement sustainability. POS give communities their individual character and identity and should be easily accessible spaces for the practice of democracy, free expression and strengthening of community ties. This study assumes that the use of a desktop study, tools such as GIS, an anonymous questionnaire and a POS assessment visit can assist in gaining a thorough understanding of the status quo in relation to the quantities, quality and accessibility of POS with social, environmental and economic benefits in Motherwell NU 1-9 as well as the perceptions of various user groups within the community. A highly inequitable distribution of POS in Motherwell NU1-9 is evident from the geospatial findings of the study. There are also varying levels of accessibility to the various POS per Neighbourhood Unit. From the assessment visit and photographic evidence, it is also clear that the various POS in Motherwell NU1-9 fail to meet the standards of quality POS as they are generally in a poor condition. The community perceptions vary according to different groupings of people within the study area. Most of the residents in Motherwell NU1-9 place value on POS with social, environmental and economic benefits and consider them a need. However, it is most unfortunate that the majority of the POS in the area do not respond to the unique needs of the residents. Finally, recommendations are made to transform the current situation of POS in Motherwell NU1-9 and assist in the provision of quality POS that are strategically located, equitably distributed and easily accessible POS that are able to accommodate all residents around the township as well as those who may be visitors.
- Full Text:
- Date Issued: 2019
- Authors: Nkonki, Busisiwe
- Date: 2019
- Subjects: Open spaces -- South Africa -- Port Elizabeth , Urban geography Human geography Land use, Urban Cities and towns
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33397 , vital:32758
- Description: Public Open Spaces (POS) with social, environmental and economic benefits are associated with the enhancement of human settlement sustainability. POS give communities their individual character and identity and should be easily accessible spaces for the practice of democracy, free expression and strengthening of community ties. This study assumes that the use of a desktop study, tools such as GIS, an anonymous questionnaire and a POS assessment visit can assist in gaining a thorough understanding of the status quo in relation to the quantities, quality and accessibility of POS with social, environmental and economic benefits in Motherwell NU 1-9 as well as the perceptions of various user groups within the community. A highly inequitable distribution of POS in Motherwell NU1-9 is evident from the geospatial findings of the study. There are also varying levels of accessibility to the various POS per Neighbourhood Unit. From the assessment visit and photographic evidence, it is also clear that the various POS in Motherwell NU1-9 fail to meet the standards of quality POS as they are generally in a poor condition. The community perceptions vary according to different groupings of people within the study area. Most of the residents in Motherwell NU1-9 place value on POS with social, environmental and economic benefits and consider them a need. However, it is most unfortunate that the majority of the POS in the area do not respond to the unique needs of the residents. Finally, recommendations are made to transform the current situation of POS in Motherwell NU1-9 and assist in the provision of quality POS that are strategically located, equitably distributed and easily accessible POS that are able to accommodate all residents around the township as well as those who may be visitors.
- Full Text:
- Date Issued: 2019
Quality in low - cost houses in Nelson Mandela Bay
- Authors: Gogela, Nwabisa
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Housing -- South Africa -- Nelson Mandela Bay Municipality Dwellings -- Defects -- 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/10948/39709 , vital:35350
- Description: Numerous low cost houses in the Nelson Mandela Bay Municipality, and all over South Africa for that matter, have been handed back to the provincial governments by beneficiaries for remedial work in a government programme called Rectification. Several houses have required demolition and be rebuilt because of patent and latent defects. Government spends huge sums of money in rectifying and fixing the defects on houses that should have been built appropriately from the start; this leads to fruitless and ineffective expenditure. The Department of Human Settlements cannot be solely blamed for the poor quality housing delivery. The contractors, project managers and the inspectors from different stakeholders involved in a project also play a massive role in certifying that the houses delivered are of required norms and standards to assist in minimizing poor quality in the delivery of the low cost housing. The funding spent in rectifying low-cost housing has caused huge backlogs, triggering protests within the communities and, regrettably, incomplete projects around the Nelson Mandela Bay Municipality, contributing to urban decay. The aim of this study was to investigate the poor and unacceptable quality in the delivery of low-cost subsidized houses in the Nelson Mandela Metro Region. The focus of the study was to scrutinize the loopholes and the ambiguities that might exist throughout the life cycle of a low cost housing project, and suggestions to mitigate common problems emerging in various projects. A qualitative research approach was followed in this study. The sample was purposively selected and comprised of 15 beneficiaries residing in the three selected NMBM (housing projects), the Ward Councilors (3), Contractors (3), the Quality Assurance Project Managers managing and foreseeing these projects(3), Quality Coordinators(3) and Inspectors from each organization, (NHBRC, ECDHS and HDA), making three (3) in total.. The study revealed that skills shortage, insufficient workforce training and lack of strict quality control are some of the factors affecting quality. Compliancy to norms and standards is not fully emphasized to the relevant stakeholders during the initiation and the commencement of the project. Tools to measure the effectiveness of quality assurance practices are currently used, but it can be argued that they are not effective enough. The study has offered a set of recommendations to address the key findings.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Nwabisa
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Housing -- South Africa -- Nelson Mandela Bay Municipality Dwellings -- Defects -- 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/10948/39709 , vital:35350
- Description: Numerous low cost houses in the Nelson Mandela Bay Municipality, and all over South Africa for that matter, have been handed back to the provincial governments by beneficiaries for remedial work in a government programme called Rectification. Several houses have required demolition and be rebuilt because of patent and latent defects. Government spends huge sums of money in rectifying and fixing the defects on houses that should have been built appropriately from the start; this leads to fruitless and ineffective expenditure. The Department of Human Settlements cannot be solely blamed for the poor quality housing delivery. The contractors, project managers and the inspectors from different stakeholders involved in a project also play a massive role in certifying that the houses delivered are of required norms and standards to assist in minimizing poor quality in the delivery of the low cost housing. The funding spent in rectifying low-cost housing has caused huge backlogs, triggering protests within the communities and, regrettably, incomplete projects around the Nelson Mandela Bay Municipality, contributing to urban decay. The aim of this study was to investigate the poor and unacceptable quality in the delivery of low-cost subsidized houses in the Nelson Mandela Metro Region. The focus of the study was to scrutinize the loopholes and the ambiguities that might exist throughout the life cycle of a low cost housing project, and suggestions to mitigate common problems emerging in various projects. A qualitative research approach was followed in this study. The sample was purposively selected and comprised of 15 beneficiaries residing in the three selected NMBM (housing projects), the Ward Councilors (3), Contractors (3), the Quality Assurance Project Managers managing and foreseeing these projects(3), Quality Coordinators(3) and Inspectors from each organization, (NHBRC, ECDHS and HDA), making three (3) in total.. The study revealed that skills shortage, insufficient workforce training and lack of strict quality control are some of the factors affecting quality. Compliancy to norms and standards is not fully emphasized to the relevant stakeholders during the initiation and the commencement of the project. Tools to measure the effectiveness of quality assurance practices are currently used, but it can be argued that they are not effective enough. The study has offered a set of recommendations to address the key findings.
- Full Text:
- Date Issued: 2019
Quality of subsidised housing in South Africa and the role of the National Home Builders Registration Council
- Authors: Motau, Simon Mosotho
- Date: 2019
- Subjects: Housing subsidies -- South Africa , Housing -- South Africa Low-income housing -- South Africa City planning -- South Africa Dwellings -- Design and construction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42374 , vital:36650
- Description: This study was motivated by a lack of quality subsidised housing in South Africa. The latter observation was made when the researcher was still employed by the NHBRC, a statutory body whose mandate is to regulate the homebuilding industry. The main aim of the study was to uncover the causes of structural defects in subsidised housing units in in South Africa and to understand the link between defects in the housing units and delivery mechanisms. The study also focused on the role of the NHBRC as the regulator of the home building industry and possible steps that can be taken to avoid delivery of poor-quality housing units. The research first focused on observation and then following these observations, the study progressed into surveys which were conducted in Soshanguve and Ga-rankuwa in the Tshwane Metropolitan Municipality, a municipality in Gauteng Province in the Republic of South Africa. The surveys were done by means of interviews and questionnaires. Interviews were conducted during face to face encounters with stakeholders such as housing beneficiaries, the municipal representatives, the inspectorate from the NHBRC and representatives from the Human Settlements Department. During the survey phase of this research, a variety of issues relating to housing construction were looked at in more detail and these included issues such as construction materials used, planning and design of housing units, climatic factors and funding. The study found that quality housing units were not provided due to the apparent lack of good planning by appropriately qualified professionals, inadequate supervision at the site and the use of inferior construction materials and/or inadequate mortar mixtures as per directions of the manufacturer. Following the research, the study found that in order to achieve quality subsidised housing units in South Africa, the NHBRC as a regulatory statutory body needed to fulfil an effective role of inspections as mandated by the state. The study also found that for quality subsidised housing units to be provided, there is a need for a new framework for planning and design of these units.
- Full Text:
- Date Issued: 2019
- Authors: Motau, Simon Mosotho
- Date: 2019
- Subjects: Housing subsidies -- South Africa , Housing -- South Africa Low-income housing -- South Africa City planning -- South Africa Dwellings -- Design and construction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42374 , vital:36650
- Description: This study was motivated by a lack of quality subsidised housing in South Africa. The latter observation was made when the researcher was still employed by the NHBRC, a statutory body whose mandate is to regulate the homebuilding industry. The main aim of the study was to uncover the causes of structural defects in subsidised housing units in in South Africa and to understand the link between defects in the housing units and delivery mechanisms. The study also focused on the role of the NHBRC as the regulator of the home building industry and possible steps that can be taken to avoid delivery of poor-quality housing units. The research first focused on observation and then following these observations, the study progressed into surveys which were conducted in Soshanguve and Ga-rankuwa in the Tshwane Metropolitan Municipality, a municipality in Gauteng Province in the Republic of South Africa. The surveys were done by means of interviews and questionnaires. Interviews were conducted during face to face encounters with stakeholders such as housing beneficiaries, the municipal representatives, the inspectorate from the NHBRC and representatives from the Human Settlements Department. During the survey phase of this research, a variety of issues relating to housing construction were looked at in more detail and these included issues such as construction materials used, planning and design of housing units, climatic factors and funding. The study found that quality housing units were not provided due to the apparent lack of good planning by appropriately qualified professionals, inadequate supervision at the site and the use of inferior construction materials and/or inadequate mortar mixtures as per directions of the manufacturer. Following the research, the study found that in order to achieve quality subsidised housing units in South Africa, the NHBRC as a regulatory statutory body needed to fulfil an effective role of inspections as mandated by the state. The study also found that for quality subsidised housing units to be provided, there is a need for a new framework for planning and design of these units.
- Full Text:
- Date Issued: 2019