Biochemical characterization of the β-mannanase activity of Bacillus paralicheniformis SVD1
- Authors: Clarke, Matthew David
- Date: 2019
- Subjects: Mycobacterium avium paratuberculosis , Enzymes -- Biotechnology , Lignocellulose -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67570 , vital:29112
- Description: Products produced via the enzymatic hydrolysis of lignocellulosic biomass, the most abundant renewable terrestrial source of carbon, can potentially replace a lot of the fuels and chemicals currently produced using non-renewable hydrocarbons. Mannan is a polysaccharide component of lignocellulose that is abundant in softwoods and legume seeds. Enzymatic hydrolysis of mannan by β-mannanases has various industrial applications, including use in biofuel and prebiotic mannooligosaccharide (MOS) production for the improvement of human and animal health. The industrial use of β-mannanases depends on their biochemical characteristics, such as their activity, stability and substrate specificity. Knowledge of their synergistic interactions with other enzymes is also useful for effective hydrolysis. Bacillus paralicheniformis SVD1 was used as a source for β-mannanases. The two mannanases of B. paralicheniformis SVD1 have not been biochemically characterized apart from minor characterization of crude β-mannanase activity. The protein sequences of the two β-mannanases, of glycosyl hydrolase family 5 and 26, have a 95% - 96% identity to the β-mannanases of B. licheniformis DSM13T (=ATCC14580T). These small protein sequence differences could lead to quite different biochemical characteristics. These mannanases were characterized as these enzymes may have industrially useful characteristics. To induce mannanase production, B. paralicheniformis SVD1 was cultured in broth containing the mannan substrate locust bean gum. Various growth curve parameters were measured over 72 h. Mannanase activity was the highest after 48 h of growth - this was the time at which mannanase activity was concentrated, using 3 kDa centrifugal filtration devices, for biochemical characterization of the crude activity. Zymography revealed that the crude concentrated mannanase fraction consisted of at least two mannanases with relative molecular weights (MWs) of 29.6 kDa and 33 kDa. This was smaller than expected – based on their theoretical molecular masses. Protease activity, which was detected in the broth, was probably the reason. There were two pH optima, pH 5.0 and pH 7.0, which also indicated the presence of two mannanases. The concentrated mannanase displayed characteristics that were expected of a B. paralicheniformis β-mannanase. The temperature optimum was 50°C and the activity loss was less than 7% at 50°C after 24 h. Substrate specificity assays revealed that there was predominantly mannanase activity present. Thin layer chromatography (TLC) analysis of mannan and MOS hydrolysis showed that mainly M2 and M3 MOS were produced; only MOS with a degree of polymerization of 4 or higher were hydrolyzed. Hydrolysis was minimal on mannoligosaccharides with galactose substituents. Activity and MOS production was the highest on soluble, low branched mannan substrates. The highest activity observed was on konjac glucomannan. Purification of the mannanase activity was then attempted using various methods. Ammonium sulfate precipitation, acetone precipitation, as well as centrifugal filtration device concentration was assessed for concentration of the mannanase activity.Concentration was not very successful due to low activity yields (≤ 20%). Anion exchange chromatography (AEC) and size exclusion chromatography (SEC) was used for purification. AEC gave good activity yield and fold purification, but SDS-PAGE analysis revealed the presence of many different proteins so further purification was necessary. SDS-PAGE analysis showed that there were only a few protein contaminants in the SEC fraction. However, the yield was too low to allow for biochemical characterization. The optimized purification procedure, which partially purified the mannanase activity, used 85% ammonium sulfate precipitation, followed by AEC. The fold purification was high (88.9) and the specific activity was 29.5 U.mg-1. A zymogram of the partially purified mannanase showed a mannanase active band with a MW of 40 - 41 kDa. A serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), was added during the purification steps. This indicated that the mannanase/s in the crude concentrate, without PMSF added, was hydrolyzed by serine protease activity. Native PAGE zymograms suggested that at least two different isoforms of mannanases were present. Additional purification would be required to determine the true characteristics of the mannanase/s. The biochemical characteristics of the crude and partially purified mannanases were similar. The pH optima of the partially purified mannanases were different; the pH optima were 6.0 and 9.0. The substrate specificities were similar, except that the partially purified mannanases displayed no cellulase and β-D-galactosidase activity, but showed a small amount of α-L-arabinase activity. The partially purified mannanase and a Cyamopsis tetragonolobus GH27 α-galactosidase synergistically hydrolyzed locust bean gum. The M50G50 combination displayed the highest extent of hydrolysis; after 24 h there was a 1.39 fold increase in reducing sugar release and the degree of synergy (DS) was 4.64. TLC analysis indicated that synergy increased the release of small MOS. These MOS could be useful as prebiotics. The synergy between the partially purified mannanase and the commercial cellulase mixture Cellic® CTec2 (Novozymes) on spent coffee grounds (SCG) was also determined. SCG is an abundant industrial waste product that has high mannan content. The SCG was pretreated using NaOH, and the monosaccharide, soluble phenolics and insoluble contents were determined. Glucose and mannose were the dominant monosaccharides in the SCG; the pretreated SCG contained 20.4% (w/w) glucose and 18.5% (w/w) mannose, respectively. The NaOH pretreatment improved mannanase hydrolysis of SCG. It resulted in the opening up and swelling of the SCG particles and removed some of the insoluble solids. The partially purified B. paralicheniformis SVD1 mannanase displayed no detectable activity on SCG, but showed synergy with CTec2, in terms of DS, on untreated and NaOH pretreated SCG. This is the first report of mannanasecellulase synergy on SCG; other studies found that increased hydrolysis was due to additive effects. The results obtained in this study are only an initial assessment of the biochemical properties of B. paralicheniformis SVD1 mannanase activity and its synergy with other enzymes. These results can be used to inform future studies.
- Full Text:
- Date Issued: 2019
- Authors: Clarke, Matthew David
- Date: 2019
- Subjects: Mycobacterium avium paratuberculosis , Enzymes -- Biotechnology , Lignocellulose -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67570 , vital:29112
- Description: Products produced via the enzymatic hydrolysis of lignocellulosic biomass, the most abundant renewable terrestrial source of carbon, can potentially replace a lot of the fuels and chemicals currently produced using non-renewable hydrocarbons. Mannan is a polysaccharide component of lignocellulose that is abundant in softwoods and legume seeds. Enzymatic hydrolysis of mannan by β-mannanases has various industrial applications, including use in biofuel and prebiotic mannooligosaccharide (MOS) production for the improvement of human and animal health. The industrial use of β-mannanases depends on their biochemical characteristics, such as their activity, stability and substrate specificity. Knowledge of their synergistic interactions with other enzymes is also useful for effective hydrolysis. Bacillus paralicheniformis SVD1 was used as a source for β-mannanases. The two mannanases of B. paralicheniformis SVD1 have not been biochemically characterized apart from minor characterization of crude β-mannanase activity. The protein sequences of the two β-mannanases, of glycosyl hydrolase family 5 and 26, have a 95% - 96% identity to the β-mannanases of B. licheniformis DSM13T (=ATCC14580T). These small protein sequence differences could lead to quite different biochemical characteristics. These mannanases were characterized as these enzymes may have industrially useful characteristics. To induce mannanase production, B. paralicheniformis SVD1 was cultured in broth containing the mannan substrate locust bean gum. Various growth curve parameters were measured over 72 h. Mannanase activity was the highest after 48 h of growth - this was the time at which mannanase activity was concentrated, using 3 kDa centrifugal filtration devices, for biochemical characterization of the crude activity. Zymography revealed that the crude concentrated mannanase fraction consisted of at least two mannanases with relative molecular weights (MWs) of 29.6 kDa and 33 kDa. This was smaller than expected – based on their theoretical molecular masses. Protease activity, which was detected in the broth, was probably the reason. There were two pH optima, pH 5.0 and pH 7.0, which also indicated the presence of two mannanases. The concentrated mannanase displayed characteristics that were expected of a B. paralicheniformis β-mannanase. The temperature optimum was 50°C and the activity loss was less than 7% at 50°C after 24 h. Substrate specificity assays revealed that there was predominantly mannanase activity present. Thin layer chromatography (TLC) analysis of mannan and MOS hydrolysis showed that mainly M2 and M3 MOS were produced; only MOS with a degree of polymerization of 4 or higher were hydrolyzed. Hydrolysis was minimal on mannoligosaccharides with galactose substituents. Activity and MOS production was the highest on soluble, low branched mannan substrates. The highest activity observed was on konjac glucomannan. Purification of the mannanase activity was then attempted using various methods. Ammonium sulfate precipitation, acetone precipitation, as well as centrifugal filtration device concentration was assessed for concentration of the mannanase activity.Concentration was not very successful due to low activity yields (≤ 20%). Anion exchange chromatography (AEC) and size exclusion chromatography (SEC) was used for purification. AEC gave good activity yield and fold purification, but SDS-PAGE analysis revealed the presence of many different proteins so further purification was necessary. SDS-PAGE analysis showed that there were only a few protein contaminants in the SEC fraction. However, the yield was too low to allow for biochemical characterization. The optimized purification procedure, which partially purified the mannanase activity, used 85% ammonium sulfate precipitation, followed by AEC. The fold purification was high (88.9) and the specific activity was 29.5 U.mg-1. A zymogram of the partially purified mannanase showed a mannanase active band with a MW of 40 - 41 kDa. A serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), was added during the purification steps. This indicated that the mannanase/s in the crude concentrate, without PMSF added, was hydrolyzed by serine protease activity. Native PAGE zymograms suggested that at least two different isoforms of mannanases were present. Additional purification would be required to determine the true characteristics of the mannanase/s. The biochemical characteristics of the crude and partially purified mannanases were similar. The pH optima of the partially purified mannanases were different; the pH optima were 6.0 and 9.0. The substrate specificities were similar, except that the partially purified mannanases displayed no cellulase and β-D-galactosidase activity, but showed a small amount of α-L-arabinase activity. The partially purified mannanase and a Cyamopsis tetragonolobus GH27 α-galactosidase synergistically hydrolyzed locust bean gum. The M50G50 combination displayed the highest extent of hydrolysis; after 24 h there was a 1.39 fold increase in reducing sugar release and the degree of synergy (DS) was 4.64. TLC analysis indicated that synergy increased the release of small MOS. These MOS could be useful as prebiotics. The synergy between the partially purified mannanase and the commercial cellulase mixture Cellic® CTec2 (Novozymes) on spent coffee grounds (SCG) was also determined. SCG is an abundant industrial waste product that has high mannan content. The SCG was pretreated using NaOH, and the monosaccharide, soluble phenolics and insoluble contents were determined. Glucose and mannose were the dominant monosaccharides in the SCG; the pretreated SCG contained 20.4% (w/w) glucose and 18.5% (w/w) mannose, respectively. The NaOH pretreatment improved mannanase hydrolysis of SCG. It resulted in the opening up and swelling of the SCG particles and removed some of the insoluble solids. The partially purified B. paralicheniformis SVD1 mannanase displayed no detectable activity on SCG, but showed synergy with CTec2, in terms of DS, on untreated and NaOH pretreated SCG. This is the first report of mannanasecellulase synergy on SCG; other studies found that increased hydrolysis was due to additive effects. The results obtained in this study are only an initial assessment of the biochemical properties of B. paralicheniformis SVD1 mannanase activity and its synergy with other enzymes. These results can be used to inform future studies.
- Full Text:
- Date Issued: 2019
Bioinformatic analysis, isolation and kinetic characterisation of red algae (Gelidium capense) dehydrogenases
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
Biological properties and interactions of Kalaharituber pfeilii
- Authors: Krele, Viwe
- Date: 2019
- Subjects: Kalaharituber pfeilii , Pezizales -- South Africa , Desert plants -- South Africa , Truffle culture -- South Africa , Plant biochemical genetics , Enzymes -- Analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72257 , vital:30022
- Description: Dessert truffles are seasonal macro fungi and have been identified in several parts of the world including South Africa. The first part of the present study dealt with the assessment of the biologically active compounds of the Kalahari truffles found in the Northern Cape of South Africa. Truffles extracts (methanol, ethanol, aqueous) were investigated for their antimicrobial properties towards Gram-positive and Gram-negative bacteria. The results demonstrated that the truffle extracts tested had no inhibitory effects against the bacterial isolates. The truffle mycelial growth was also noted to be ineffective against the selected bacteria. The bacteria tested in the present study showed some antagonistic effects against the fungus. Cultures of K. pfeilii were also screened for enzyme production including amylase, protease, cellulose, and laccase. Evaluation of the potential of K. pfeilii mycelia to produce these industrially and economically important enzymes demonstrated both amylase and protease activity. However, for laccase and cellulose, no activity was detected. The second part of the present study aimed at optimizing biomass production by K. pfeilii in liquid culture media. FF Microplate containing 95 discreet carbon sources were employed to test for substrate utilization. Blanked readings above 0.1 were regarded as positive for utilization, and 4 substrates were selected as potential substrates and were included in liquid media. Media was evaluated for mycelial biomass production. Of the carbon sources tested sucrose proved to be the most suitable for supporting mycelial growth. The third part of the current study included investigating the diversity of microbial communities colonizing the rhizosheath of Stipagrostis ciliata var. capensis (the host plant of K. pfeilii) and these were identified by means of next-generation sequencing using Illumina Miseq. Bioinformatics tools were utilized in analyzing the data. Actinobacteria were found to be the most dominant bacterial phylum, followed by unclassified bacteria, Proteobacteria, and Acidobacteria. The top 25 sequences were selected and clustered into bacterial OTUs (at 97% threshold) which were assigned into 1 phylum (Actinobacteria), 1 family (Geodermatophilaceae) and 23 genera. This phylum is well known for its secondary metabolites. Streptomyces sp. was the most frequently encountered genus. The results from this study necessitate further investigations with regards to the function and evolution of fungal-bacterial associations. Wheather these bacteria have a contribution towards the truffle development, it is still not confirmed.
- Full Text:
- Date Issued: 2019
- Authors: Krele, Viwe
- Date: 2019
- Subjects: Kalaharituber pfeilii , Pezizales -- South Africa , Desert plants -- South Africa , Truffle culture -- South Africa , Plant biochemical genetics , Enzymes -- Analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72257 , vital:30022
- Description: Dessert truffles are seasonal macro fungi and have been identified in several parts of the world including South Africa. The first part of the present study dealt with the assessment of the biologically active compounds of the Kalahari truffles found in the Northern Cape of South Africa. Truffles extracts (methanol, ethanol, aqueous) were investigated for their antimicrobial properties towards Gram-positive and Gram-negative bacteria. The results demonstrated that the truffle extracts tested had no inhibitory effects against the bacterial isolates. The truffle mycelial growth was also noted to be ineffective against the selected bacteria. The bacteria tested in the present study showed some antagonistic effects against the fungus. Cultures of K. pfeilii were also screened for enzyme production including amylase, protease, cellulose, and laccase. Evaluation of the potential of K. pfeilii mycelia to produce these industrially and economically important enzymes demonstrated both amylase and protease activity. However, for laccase and cellulose, no activity was detected. The second part of the present study aimed at optimizing biomass production by K. pfeilii in liquid culture media. FF Microplate containing 95 discreet carbon sources were employed to test for substrate utilization. Blanked readings above 0.1 were regarded as positive for utilization, and 4 substrates were selected as potential substrates and were included in liquid media. Media was evaluated for mycelial biomass production. Of the carbon sources tested sucrose proved to be the most suitable for supporting mycelial growth. The third part of the current study included investigating the diversity of microbial communities colonizing the rhizosheath of Stipagrostis ciliata var. capensis (the host plant of K. pfeilii) and these were identified by means of next-generation sequencing using Illumina Miseq. Bioinformatics tools were utilized in analyzing the data. Actinobacteria were found to be the most dominant bacterial phylum, followed by unclassified bacteria, Proteobacteria, and Acidobacteria. The top 25 sequences were selected and clustered into bacterial OTUs (at 97% threshold) which were assigned into 1 phylum (Actinobacteria), 1 family (Geodermatophilaceae) and 23 genera. This phylum is well known for its secondary metabolites. Streptomyces sp. was the most frequently encountered genus. The results from this study necessitate further investigations with regards to the function and evolution of fungal-bacterial associations. Wheather these bacteria have a contribution towards the truffle development, it is still not confirmed.
- Full Text:
- Date Issued: 2019
Block copolymer templates for metal oxide nanostructures
- Authors: Talla, Assane
- Date: 2019
- Subjects: Nanotechnology , Nanostructured materials Metal oxide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43889 , vital:37075
- Description: Recent advances in technology have increased the need for fabrication of devices with feature sizes of tens of nanometers, such as ultra-fine filters or membranes, and high density data storage media, to name a few. For this reason, research is now focused on block copolymer nanolithographic processes, particularly the fabrication of nanoscale templates with domains well below 100 nm. Block copolymers have the tendency to self-organise into various structures, such as lamellae, spheres or cylinders on a nanometer scale. Among these possible configurations, the perpendicular cylindrical structure is most desirable, because it can be used for templates or masks for feature development, in particular, oriented wires or rods. In this work, the aim is to create a nano-mask from a di-block copolymer thin film, for zinc oxide nanorods growth. For this purpose poly (styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask. Samples were characterized using X-ray reflectometry to determine the thicknesses of the PS-b-PMMA thin films, while scanning probe microscopy and scanning electron microscopy was used to investigate the surface morphology of the samples. PS-b-PMMA thin films were produced on a random copolymer (poly (styrene-random-methylmethacrylate) (PS-r-PMMA) coated onto a silicon substrate. The PS-r-PMMA permits a non-preferential interaction between the di-block constituents and the substrate. Thermal annealing in vacuum of PS-b-PMMA on PS-r-PMMA led to perpendicular cylinders of PMMA within a PS matrix in the di-block. The typical thicknesses measured for the di-block copolymer films ranged between 33 nm and 37 nm. During this study, a perpendicular orientation of the di-block components was also produced when PS-b-PMMA was spun onto a layer of zinc oxide nanoparticles and thermally annealed in vacuum. It was shown that the ZnO nanoparticles created a corrugated surface on silicon which induced perpendicular cylinders of PMMA within the PS matrix. This was possible for a specific surface roughness parameter and film thickness. In this case, the typical thickness determined for the di-block copolymer ranged between 33 and 35 nm and the surface roughness parameter was 0.07. For the fabrication of a di-block template or PS nano-mask, the vertically oriented PMMA cylindrical nanodomains in the PS matrix were removed by exposing the film to ultraviolet radiation at an adequate dose, followed successively by washing in acetic acid and de-ionized water. It was shown that ultraviolet exposure is necessary to ensure the degradation of PMMA. A subsequent rinse in glacial acetic acid and DI water of the film exposed to ultraviolet, left an array of ordered nanoscopic pores with sizes ranging between 10 nm and 20 nm. Finally, the growth of ZnO nanorods on the di-block template produced on zinc oxide nanoparticles, was attempted using an aqueous solution based-method, namely chemical bath deposition. The rods did not grow inside the nanopores, probably due to poor capillary action. In additional experiments, the di-block template was removed by toluene (a selective solvent for PS) followed by the growth of ZnO rods on the exposed nanoparticle surface. Vertical and well separated ZnO rods formed on this surface, in places where the underlying seed layer had been attacked by the acetic acid treatment during removal of the PMMA. The observed ZnO rod morphology can be used in applications such as solar cell.
- Full Text:
- Date Issued: 2019
- Authors: Talla, Assane
- Date: 2019
- Subjects: Nanotechnology , Nanostructured materials Metal oxide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43889 , vital:37075
- Description: Recent advances in technology have increased the need for fabrication of devices with feature sizes of tens of nanometers, such as ultra-fine filters or membranes, and high density data storage media, to name a few. For this reason, research is now focused on block copolymer nanolithographic processes, particularly the fabrication of nanoscale templates with domains well below 100 nm. Block copolymers have the tendency to self-organise into various structures, such as lamellae, spheres or cylinders on a nanometer scale. Among these possible configurations, the perpendicular cylindrical structure is most desirable, because it can be used for templates or masks for feature development, in particular, oriented wires or rods. In this work, the aim is to create a nano-mask from a di-block copolymer thin film, for zinc oxide nanorods growth. For this purpose poly (styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask. Samples were characterized using X-ray reflectometry to determine the thicknesses of the PS-b-PMMA thin films, while scanning probe microscopy and scanning electron microscopy was used to investigate the surface morphology of the samples. PS-b-PMMA thin films were produced on a random copolymer (poly (styrene-random-methylmethacrylate) (PS-r-PMMA) coated onto a silicon substrate. The PS-r-PMMA permits a non-preferential interaction between the di-block constituents and the substrate. Thermal annealing in vacuum of PS-b-PMMA on PS-r-PMMA led to perpendicular cylinders of PMMA within a PS matrix in the di-block. The typical thicknesses measured for the di-block copolymer films ranged between 33 nm and 37 nm. During this study, a perpendicular orientation of the di-block components was also produced when PS-b-PMMA was spun onto a layer of zinc oxide nanoparticles and thermally annealed in vacuum. It was shown that the ZnO nanoparticles created a corrugated surface on silicon which induced perpendicular cylinders of PMMA within the PS matrix. This was possible for a specific surface roughness parameter and film thickness. In this case, the typical thickness determined for the di-block copolymer ranged between 33 and 35 nm and the surface roughness parameter was 0.07. For the fabrication of a di-block template or PS nano-mask, the vertically oriented PMMA cylindrical nanodomains in the PS matrix were removed by exposing the film to ultraviolet radiation at an adequate dose, followed successively by washing in acetic acid and de-ionized water. It was shown that ultraviolet exposure is necessary to ensure the degradation of PMMA. A subsequent rinse in glacial acetic acid and DI water of the film exposed to ultraviolet, left an array of ordered nanoscopic pores with sizes ranging between 10 nm and 20 nm. Finally, the growth of ZnO nanorods on the di-block template produced on zinc oxide nanoparticles, was attempted using an aqueous solution based-method, namely chemical bath deposition. The rods did not grow inside the nanopores, probably due to poor capillary action. In additional experiments, the di-block template was removed by toluene (a selective solvent for PS) followed by the growth of ZnO rods on the exposed nanoparticle surface. Vertical and well separated ZnO rods formed on this surface, in places where the underlying seed layer had been attacked by the acetic acid treatment during removal of the PMMA. The observed ZnO rod morphology can be used in applications such as solar cell.
- Full Text:
- Date Issued: 2019
BODIPY and porphyrin dyes for direct glucose sensing and optical limiting applications
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
Bootstrap-based tolerance intervals for photovoltaic energy yield assessments
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
Carbon and nutrient storage of the Swartkops Estuary salt marsh and seagrass habitats
- Authors: Els, Jessica
- Date: 2019
- Subjects: Estuarine ecology -- South Africa -- Swartkops River Estuary , Salt marsh ecology -- South Africa -- Swartkops River Estuary Seagrasses -- Ecology Seagrasses -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42196 , vital:36634
- Description: Coastal wetlands play an important role in filtering nutrient contaminants from water bodies and are also effective carbon sinks. These systems are known as blue carbon ecosystems. Blue carbon is defined as the carbon stored and sequestered by coastal vegetated habitats such as seagrasses, salt marsh and mangroves. These habitats are being lost on a global scale due to climate change and other anthropogenic pressures. Quantifying ecosystem services provided by these habitats may lead to better conservation and restoration strategies. Research on this topic has escalated over the past decade but there are no published studies in South Africa. The aim of this study was to quantify the carbon, nitrogen, and phosphorus stocks in the above and below ground tissues of Zostera capensis, Spartina maritima, and Salicornia tegetaria — a seagrass, salt marsh grass, and salt marsh succulent. This was done in both summer and winter to understand the variability of carbon and nutrient storage. The organic carbon stock of the sediment beneath these three species was also quantified. Results showed that S. maritima, S. tegetaria, and Z. capensis stored 16 ± 2.9 Mg C. ha-1, 4.3 ± 0.7 Mg C. ha-1, and 2.1 ± 0.5 Mg C. ha-1 in their respective biomass, and 247 ± 48 Mg C. ha-1, 212 ± 44 Mg C. ha-1, and 224 ± 38 Mg C. ha-1 respectively in the sediment beneath these habitats. This was determined by elemental analysis and the loss on ignition method (LOI). The sediment made up the dominant carbon pool in the estuary and there was very little seasonal variation, however spatial variation was evident. The sediment carbon stocks were similar to the global mean for salt marsh (255 Mg C. ha-1) and greater than the global mean for seagrass (108 Mg C. ha-1). The Swartkops Estuary stored a total (biomass and sediment carbon combined) of 14 094 Mg C in the Z. capensis area of 62 ha, 25 286 Mg C in the S. maritima area of 96 ha, and 5 916 Mg C in the S. tegetaria, covering an area of 27 ha. This is significantly less than what has been found globally in estuaries, but this is largely due to the smaller area cover of these macrophytes. The amount of carbon stored per hectare is much larger in this South African system than in many international studies — possibly due to the high levels of pollution coming into the system. Nitrogen and phosphorus stocks in the plants fluctuated seasonally in relation to the nutrient input to the estuary, with the greatest stocks found in winter in Z. capensis, S. maritima, and S. tegetaria (0.42 ± 0.03 Mg N. ha-1, 1.6 ± 0.13 Mg N. ha-1, and 0.37 ± 0.02 Mg N. ha-1, respectively; and 0.4 ± 0.03 Mg P. ha-1, 1.2 ± 0.10 Mg P. ha-1 in Z. capensis and S. maritima respectively) because nutrient inputs to the system were highest in winter, however the P stocks in S. tegetaria were greatest in summer (0.35 ± 0.04 Mg P. ha-1). The reason for this difference is because of their ability to store phosphorus better than nitrogen and for longer periods of time due to luxury uptake. Salicornia tegetaria N and P stocks were also lower than the other two species, possibly due to its placement along the intertidal gradient, as it is not tidally inundated for as long as the other two species. The Z. capensis and S. maritima at Site 1 showed extremely high amounts of nitrogen in their tissues (105.3 ± 1.6 g kg-1 and 74.91 ± 4.1 g kg-1 respectively). This is due to the area being a depositional site as it was an old oyster farm and experiences little tidal flushing from the sea despite its proximity to the mouth. Nutrient ratios and N: biomass were determined as an indication of nutrient pollution. The N: biomass was low in both seasons in Z. capensis, S. maritima, and S. tegetaria (0.08, 0.02, 0.04 respectively) indicating consistant eutrophic conditions in the estuary. Plant biomass was a better indicator of nutrient pollution than epiphytes which were very low in the Swartkops Estuary and did not prove as a useful indicator of nutrient enrichment. These results can inform local management plans of the ecosystem service potential of these species and how they should be protected for future and current sustainable use as filters for nutrient pollution to keep the water quality in a better state. It also outlines the current state of blue carbon and nutrient stocks in an urban South African estuary.
- Full Text:
- Date Issued: 2019
- Authors: Els, Jessica
- Date: 2019
- Subjects: Estuarine ecology -- South Africa -- Swartkops River Estuary , Salt marsh ecology -- South Africa -- Swartkops River Estuary Seagrasses -- Ecology Seagrasses -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42196 , vital:36634
- Description: Coastal wetlands play an important role in filtering nutrient contaminants from water bodies and are also effective carbon sinks. These systems are known as blue carbon ecosystems. Blue carbon is defined as the carbon stored and sequestered by coastal vegetated habitats such as seagrasses, salt marsh and mangroves. These habitats are being lost on a global scale due to climate change and other anthropogenic pressures. Quantifying ecosystem services provided by these habitats may lead to better conservation and restoration strategies. Research on this topic has escalated over the past decade but there are no published studies in South Africa. The aim of this study was to quantify the carbon, nitrogen, and phosphorus stocks in the above and below ground tissues of Zostera capensis, Spartina maritima, and Salicornia tegetaria — a seagrass, salt marsh grass, and salt marsh succulent. This was done in both summer and winter to understand the variability of carbon and nutrient storage. The organic carbon stock of the sediment beneath these three species was also quantified. Results showed that S. maritima, S. tegetaria, and Z. capensis stored 16 ± 2.9 Mg C. ha-1, 4.3 ± 0.7 Mg C. ha-1, and 2.1 ± 0.5 Mg C. ha-1 in their respective biomass, and 247 ± 48 Mg C. ha-1, 212 ± 44 Mg C. ha-1, and 224 ± 38 Mg C. ha-1 respectively in the sediment beneath these habitats. This was determined by elemental analysis and the loss on ignition method (LOI). The sediment made up the dominant carbon pool in the estuary and there was very little seasonal variation, however spatial variation was evident. The sediment carbon stocks were similar to the global mean for salt marsh (255 Mg C. ha-1) and greater than the global mean for seagrass (108 Mg C. ha-1). The Swartkops Estuary stored a total (biomass and sediment carbon combined) of 14 094 Mg C in the Z. capensis area of 62 ha, 25 286 Mg C in the S. maritima area of 96 ha, and 5 916 Mg C in the S. tegetaria, covering an area of 27 ha. This is significantly less than what has been found globally in estuaries, but this is largely due to the smaller area cover of these macrophytes. The amount of carbon stored per hectare is much larger in this South African system than in many international studies — possibly due to the high levels of pollution coming into the system. Nitrogen and phosphorus stocks in the plants fluctuated seasonally in relation to the nutrient input to the estuary, with the greatest stocks found in winter in Z. capensis, S. maritima, and S. tegetaria (0.42 ± 0.03 Mg N. ha-1, 1.6 ± 0.13 Mg N. ha-1, and 0.37 ± 0.02 Mg N. ha-1, respectively; and 0.4 ± 0.03 Mg P. ha-1, 1.2 ± 0.10 Mg P. ha-1 in Z. capensis and S. maritima respectively) because nutrient inputs to the system were highest in winter, however the P stocks in S. tegetaria were greatest in summer (0.35 ± 0.04 Mg P. ha-1). The reason for this difference is because of their ability to store phosphorus better than nitrogen and for longer periods of time due to luxury uptake. Salicornia tegetaria N and P stocks were also lower than the other two species, possibly due to its placement along the intertidal gradient, as it is not tidally inundated for as long as the other two species. The Z. capensis and S. maritima at Site 1 showed extremely high amounts of nitrogen in their tissues (105.3 ± 1.6 g kg-1 and 74.91 ± 4.1 g kg-1 respectively). This is due to the area being a depositional site as it was an old oyster farm and experiences little tidal flushing from the sea despite its proximity to the mouth. Nutrient ratios and N: biomass were determined as an indication of nutrient pollution. The N: biomass was low in both seasons in Z. capensis, S. maritima, and S. tegetaria (0.08, 0.02, 0.04 respectively) indicating consistant eutrophic conditions in the estuary. Plant biomass was a better indicator of nutrient pollution than epiphytes which were very low in the Swartkops Estuary and did not prove as a useful indicator of nutrient enrichment. These results can inform local management plans of the ecosystem service potential of these species and how they should be protected for future and current sustainable use as filters for nutrient pollution to keep the water quality in a better state. It also outlines the current state of blue carbon and nutrient stocks in an urban South African estuary.
- Full Text:
- Date Issued: 2019
Categorising Network Telescope data using big data enrichment techniques
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
Causes of road projects’ delays: a case of Blantyre
- Authors: Mwamvani, Henry Duncan John
- Date: 2019
- Subjects: Construction industry -- Management , Engineering -- Management Project management Building -- Planning Building -- Superintendance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41719 , vital:36575
- Description: The Construction Industry (CI) is recognised as a formidable sector that has the potential of facilitating the growth and development of a nation’s economy by providing the necessary infrastructure that is required to spur the growth of other industries. In many countries, such as Malawi, the city councils (CCs) also influence the implementation and management of such infrastructure as mandated by the Malawi Local Government Act (1998). Successful projects should be implemented in such a manner that completion of the projects is within the golden triangle of cost, time and quality. This implies that projects are completed within the planned budget, stipulated time and specified quality. City Councils in Malawi, however, face various challenges in their implementation of infrastructure projects leading to delayed project completion, resulting in extended project implementation periods. This study aimed at finding the causes of road projects construction delays in Blantyre City Council, (BCC) which is one of the four CCs in Malawi, the second largest and the commercial capital. The study followed a qualitative research method using a case study approach. This study combined in-depth, face-to-face interviews of identified stakeholders with general routine work observations and project document gathering to collect the primary data while secondary data was obtained from books, research journal articles, government documents, unpublished theses, some international organisation reports, general internet information and other academic related sources of relevant information. The participants included council representatives (council service committee chairperson, secretariat management staff), contractors’ representatives and consultants’ representatives. The participants were chosen using a non-probability sampling method of purposive and snowball selection, targeting their involvement in the previous and/or the current project implementation cycles. The study also involved visiting some of the ongoing and completed projects and collecting project photographs. The findings from the case study revealed challenges the council faced due to a shortage of engineers in conducting detailed proposed projects surveys resulting in incomplete project scope definition (detailed designs) on some projects, before the procurement of contractors as the major cause of project construction delays. Other factors that were identified were: service providers delaying the removal of existing public utility infrastructure from project sites, inclement weather and the client delays in issuing instructions to the contractors during the implementation of the projects. Another factor was the shortage of construction equipment and construction materials by some contractors. Based on the research findings, the main recommendation is to increase the number of technical employees, especially engineers and other key technical staff such as quantity surveyors by improving the employees’ conditions of service. Improving the service conditions will attract and retain the right quality and quantity of technical employees to undertake the management of the construction projects. Alternatively, all positions for professionals who are deemed as scarce or hard to maintain could be placed on a contract basis, renewable after a period of two to three years. This would be able to attract those professionals who are ready to offer their expertise for a certain period but may not necessarily want to work until the government mandatory retirement. This will be in addition to the engagement of external project consultants to assist in project management, which the council started implementing in 2017. As for the delay in the removal of utility services infrastructure on proposed project sites, the client needs to commence with the process early in the planning and procurement process before handing over the project sites to the contractors. General contractor delay causes can be minimised by raising the selection criteria of contractors to flush out as well as black-listing incompetent contractors.
- Full Text:
- Date Issued: 2019
- Authors: Mwamvani, Henry Duncan John
- Date: 2019
- Subjects: Construction industry -- Management , Engineering -- Management Project management Building -- Planning Building -- Superintendance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41719 , vital:36575
- Description: The Construction Industry (CI) is recognised as a formidable sector that has the potential of facilitating the growth and development of a nation’s economy by providing the necessary infrastructure that is required to spur the growth of other industries. In many countries, such as Malawi, the city councils (CCs) also influence the implementation and management of such infrastructure as mandated by the Malawi Local Government Act (1998). Successful projects should be implemented in such a manner that completion of the projects is within the golden triangle of cost, time and quality. This implies that projects are completed within the planned budget, stipulated time and specified quality. City Councils in Malawi, however, face various challenges in their implementation of infrastructure projects leading to delayed project completion, resulting in extended project implementation periods. This study aimed at finding the causes of road projects construction delays in Blantyre City Council, (BCC) which is one of the four CCs in Malawi, the second largest and the commercial capital. The study followed a qualitative research method using a case study approach. This study combined in-depth, face-to-face interviews of identified stakeholders with general routine work observations and project document gathering to collect the primary data while secondary data was obtained from books, research journal articles, government documents, unpublished theses, some international organisation reports, general internet information and other academic related sources of relevant information. The participants included council representatives (council service committee chairperson, secretariat management staff), contractors’ representatives and consultants’ representatives. The participants were chosen using a non-probability sampling method of purposive and snowball selection, targeting their involvement in the previous and/or the current project implementation cycles. The study also involved visiting some of the ongoing and completed projects and collecting project photographs. The findings from the case study revealed challenges the council faced due to a shortage of engineers in conducting detailed proposed projects surveys resulting in incomplete project scope definition (detailed designs) on some projects, before the procurement of contractors as the major cause of project construction delays. Other factors that were identified were: service providers delaying the removal of existing public utility infrastructure from project sites, inclement weather and the client delays in issuing instructions to the contractors during the implementation of the projects. Another factor was the shortage of construction equipment and construction materials by some contractors. Based on the research findings, the main recommendation is to increase the number of technical employees, especially engineers and other key technical staff such as quantity surveyors by improving the employees’ conditions of service. Improving the service conditions will attract and retain the right quality and quantity of technical employees to undertake the management of the construction projects. Alternatively, all positions for professionals who are deemed as scarce or hard to maintain could be placed on a contract basis, renewable after a period of two to three years. This would be able to attract those professionals who are ready to offer their expertise for a certain period but may not necessarily want to work until the government mandatory retirement. This will be in addition to the engagement of external project consultants to assist in project management, which the council started implementing in 2017. As for the delay in the removal of utility services infrastructure on proposed project sites, the client needs to commence with the process early in the planning and procurement process before handing over the project sites to the contractors. General contractor delay causes can be minimised by raising the selection criteria of contractors to flush out as well as black-listing incompetent contractors.
- Full Text:
- Date Issued: 2019
Chacma baboons (papio ursinus) influence zoogeomorphic processes in the Karoo through rock movement
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019
Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Authors: Iwu, Chidozie Declan
- Date: 2019
- Subjects: Listeria monocytogenes Enterobacteriaceae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17187 , vital:40864
- Description: Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Full Text:
- Date Issued: 2019
- Authors: Iwu, Chidozie Declan
- Date: 2019
- Subjects: Listeria monocytogenes Enterobacteriaceae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17187 , vital:40864
- Description: Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Full Text:
- Date Issued: 2019
Chitin hydrolysis with chitinolytic enzymes for the production of chitooligomers with antimicrobial properties
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
Climatic suitability of Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), a shoot-boring moth for the biological control of Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) in South Africa
- Authors: Nqayi, Slindile Brightness
- Date: 2019
- Subjects: CLIMEX , Chromolaena odorata -- Biological control -- South Africa , Tortricidae -- South Africa , Bioclimatology -- Software
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92208 , vital:30681
- Description: Biological control using natural enemies introduced from the native range is an integral component of the management of Chromolaena odorata, a serious invader in the eastern regions of South Africa. A number of biological control agents for C. odorata have been released in South Africa, and one of them, Dichrorampha odorata, has failed to establish. To understand if D. odorata failed to establish due to climate incompatibility, its thermal physiology was investigated. Thermal tolerance data were used to determine the developmental thresholds and number of generations that D. odorata is capable of going through in South Africa per year. These predictions were generated using CLIMEX temperature data and the degree-day parameters K and t0. Developmental time decreased with increasing temperatures ranging from 20 °C to 30°C, with immature stages not able to complete development at 18°C and 32°C. The developmental threshold, to, was determined as 8.45 °C with 872.4 degree-days required to complete development (K), indicating that D. odorata is capable of producing a maximum number of 6.5 generations per year in South Africa. The CLIMEX data indicated that the east coast regions of South Africa, which are the heaviest invaded areas by C. odorata in South Africa, were climatically most suitable for D. odorata to. D. odorata lower (LLT50) and upper (ULT50) lethal temperatures were -4.5°C and 39.64°C for larvae and 1.83 and 41.02°C for adults, and D. odorata adults were able to maintain locomotory functioning at 4.4 to 43.7°C, respectively. Acclimation at low and high temperatures indicate that when D. odorata was kept at a lower temperature of 20°C for 7 days, it became tolerant to warmer and cooler temperatures (1.95 and 44.41°C) when compared to D. odorata reared at 25°C (3.36 and 43.67°C) and 30°C (5.92 and 42.93°C). Dichrorampha odorata is therefore climatically suitable for release and should establish in South Africa to control C. odorata. The establishment and persistence of D. odorata will not be limited by climatic conditions but rather the distribution of its host weed, C. odorata in South Africa. Also, this study presents a decision-making protocol for the release of D. odorata to allow better performance in the field.
- Full Text:
- Date Issued: 2019
- Authors: Nqayi, Slindile Brightness
- Date: 2019
- Subjects: CLIMEX , Chromolaena odorata -- Biological control -- South Africa , Tortricidae -- South Africa , Bioclimatology -- Software
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92208 , vital:30681
- Description: Biological control using natural enemies introduced from the native range is an integral component of the management of Chromolaena odorata, a serious invader in the eastern regions of South Africa. A number of biological control agents for C. odorata have been released in South Africa, and one of them, Dichrorampha odorata, has failed to establish. To understand if D. odorata failed to establish due to climate incompatibility, its thermal physiology was investigated. Thermal tolerance data were used to determine the developmental thresholds and number of generations that D. odorata is capable of going through in South Africa per year. These predictions were generated using CLIMEX temperature data and the degree-day parameters K and t0. Developmental time decreased with increasing temperatures ranging from 20 °C to 30°C, with immature stages not able to complete development at 18°C and 32°C. The developmental threshold, to, was determined as 8.45 °C with 872.4 degree-days required to complete development (K), indicating that D. odorata is capable of producing a maximum number of 6.5 generations per year in South Africa. The CLIMEX data indicated that the east coast regions of South Africa, which are the heaviest invaded areas by C. odorata in South Africa, were climatically most suitable for D. odorata to. D. odorata lower (LLT50) and upper (ULT50) lethal temperatures were -4.5°C and 39.64°C for larvae and 1.83 and 41.02°C for adults, and D. odorata adults were able to maintain locomotory functioning at 4.4 to 43.7°C, respectively. Acclimation at low and high temperatures indicate that when D. odorata was kept at a lower temperature of 20°C for 7 days, it became tolerant to warmer and cooler temperatures (1.95 and 44.41°C) when compared to D. odorata reared at 25°C (3.36 and 43.67°C) and 30°C (5.92 and 42.93°C). Dichrorampha odorata is therefore climatically suitable for release and should establish in South Africa to control C. odorata. The establishment and persistence of D. odorata will not be limited by climatic conditions but rather the distribution of its host weed, C. odorata in South Africa. Also, this study presents a decision-making protocol for the release of D. odorata to allow better performance in the field.
- Full Text:
- Date Issued: 2019
Comparing organic and conventional farming systems in George, South Africa
- Authors: Swanepoel, Marike
- Date: 2019
- Subjects: Organic farming -- South Africa -- George , Sustainable agriculture -- South Africa -- George Agricultural systems -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43946 , vital:37086
- Description: This study presents some of the findings of a long-term comparative study at the Nelson Mandela University George campus which started in 2014. This research compares the differences in crop yields and soil fertility under conventional and organic farming systems. Although previous research that was conducted will be presented briefly, the main focus of this dissertation is to report on the research results generated during the 2016/17 and 2017/18 cropping seasons. The baseline study (indicator measurements) was done in 2014 and investigated soil fertility before the different farming systems were implemented. The rapid increase in human population threatens food security, especially in developing countries. Climate change together with the degradation of soil and other natural resources due to high-input industrial farming, provide further challenges in terms of agriculture and future food security. Agricultural production in South Africa faces three obstacles: water scarcity, infertile soils and poor institutional support. Therefore, regenerative and sustainable agriculture practices such as organic farming, are increasingly being promoted as an alternative to conventional farming systems in southern Africa. What is the best way of farming? This is the question every farmer is confronted with. Some say organic whilst others say conventional, but how do we determine this? What is the role of crop rotation in pest management, soil fertility and crop yield? So we set up the research to compare the two farming systems so that decisions can be based on sound scientific findings. Results showed a significant increase in the case of the organic yield in season 2016/17 for cabbage and in both seasons (2016/17 & 2017/18) for cowpea and sweet potato, proving that organic farming yields can increase over time. Soil fertility changes from the baseline year (2014) till the end of season 2017/18 were compared. Overall organic farming systems showed very promising results with higher levels of soil pH followed by a significant increase in important soil nutrients (P, K & C) compared to conventional systems. Crop rotation also had positive effects.
- Full Text:
- Date Issued: 2019
- Authors: Swanepoel, Marike
- Date: 2019
- Subjects: Organic farming -- South Africa -- George , Sustainable agriculture -- South Africa -- George Agricultural systems -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43946 , vital:37086
- Description: This study presents some of the findings of a long-term comparative study at the Nelson Mandela University George campus which started in 2014. This research compares the differences in crop yields and soil fertility under conventional and organic farming systems. Although previous research that was conducted will be presented briefly, the main focus of this dissertation is to report on the research results generated during the 2016/17 and 2017/18 cropping seasons. The baseline study (indicator measurements) was done in 2014 and investigated soil fertility before the different farming systems were implemented. The rapid increase in human population threatens food security, especially in developing countries. Climate change together with the degradation of soil and other natural resources due to high-input industrial farming, provide further challenges in terms of agriculture and future food security. Agricultural production in South Africa faces three obstacles: water scarcity, infertile soils and poor institutional support. Therefore, regenerative and sustainable agriculture practices such as organic farming, are increasingly being promoted as an alternative to conventional farming systems in southern Africa. What is the best way of farming? This is the question every farmer is confronted with. Some say organic whilst others say conventional, but how do we determine this? What is the role of crop rotation in pest management, soil fertility and crop yield? So we set up the research to compare the two farming systems so that decisions can be based on sound scientific findings. Results showed a significant increase in the case of the organic yield in season 2016/17 for cabbage and in both seasons (2016/17 & 2017/18) for cowpea and sweet potato, proving that organic farming yields can increase over time. Soil fertility changes from the baseline year (2014) till the end of season 2017/18 were compared. Overall organic farming systems showed very promising results with higher levels of soil pH followed by a significant increase in important soil nutrients (P, K & C) compared to conventional systems. Crop rotation also had positive effects.
- Full Text:
- Date Issued: 2019
Comparison of mesozooplankton communities at three shallow seamounts in the South West Indian Ocean using size spectrum analysis
- Rasoloarijao, Zo, Huggett, Jenny
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
Computational fluid dynamics design and performance testing of a cyclone heat exchanger used in a gasification plant
- Authors: George, Tomy
- Date: 2019
- Subjects: Computational fluid dynamics Renewable energy sources Biomass gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19087 , vital:39877
- Description: Renewable energy resources are considered to be the most promising source of energy in the coming centuries owing to its potential to get replenished by the nature itself. However, there are a number of challenges that are to be addressed prior to considering a particular resource as a reliable and effective one according to the energy demand fluctuations. Energy extracted from the biomass available in the nature has a lot of potential especially in the case of producing energy from syngas produced by the controlled burning of wood. This research deals with the minimisation of energy wastage in a gasification plant where syngas is produced from wood and transferred to an internal combustion engine to further generate electrical energy. The syngas produced from the wood is to be fed through a cyclone for purification before it can be fed into the IC engine, where the dust, carbon and other impurities are separated from the syngas by making use of the centrifugal force developed inside the cyclone. This syngas is further cooled and fed into the IC engine in its purest form as specified by the requirements of the engine. It is envisaged that if it is possible to recover the heat energy otherwise wasted in the cyclone and through the cooling circuit, it can be used for preheating the wood or for other minor heating purposes, and thereby the heat wastage can be minimised. Therefore, in this research, a series of numerical investigation conducted which involved the modelling of heat exchanger around a cyclone in order to extract heat from the surface of the cyclone. Two basic design of the Heat exchanger were considered in the study, a rectangular and a conical design. With a water flow rate of 2 l/min in conical design, the heat absorbed by the water was found to be 5.555 kJ/s and in rectangular design, the heat absorbed by the water was 4.872 kJ/s. An experimental analysis conducted to validate the simulation by a rectangular Heat exchanger shows the amount of heat absorbed by the water is 4.87 kJ/s. In a study with variable water flow rate through the jacket, it is observed that heat absorbed by the water in conical heat exchanger is more than heat absorbed by the water in rectangular jacket within the flow rate of 4 l/min. and the heat absorbed by the water in rectangular heat exchanger is higher than conical heat exchanger with water flow rate above 4 l/min.
- Full Text:
- Date Issued: 2019
- Authors: George, Tomy
- Date: 2019
- Subjects: Computational fluid dynamics Renewable energy sources Biomass gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19087 , vital:39877
- Description: Renewable energy resources are considered to be the most promising source of energy in the coming centuries owing to its potential to get replenished by the nature itself. However, there are a number of challenges that are to be addressed prior to considering a particular resource as a reliable and effective one according to the energy demand fluctuations. Energy extracted from the biomass available in the nature has a lot of potential especially in the case of producing energy from syngas produced by the controlled burning of wood. This research deals with the minimisation of energy wastage in a gasification plant where syngas is produced from wood and transferred to an internal combustion engine to further generate electrical energy. The syngas produced from the wood is to be fed through a cyclone for purification before it can be fed into the IC engine, where the dust, carbon and other impurities are separated from the syngas by making use of the centrifugal force developed inside the cyclone. This syngas is further cooled and fed into the IC engine in its purest form as specified by the requirements of the engine. It is envisaged that if it is possible to recover the heat energy otherwise wasted in the cyclone and through the cooling circuit, it can be used for preheating the wood or for other minor heating purposes, and thereby the heat wastage can be minimised. Therefore, in this research, a series of numerical investigation conducted which involved the modelling of heat exchanger around a cyclone in order to extract heat from the surface of the cyclone. Two basic design of the Heat exchanger were considered in the study, a rectangular and a conical design. With a water flow rate of 2 l/min in conical design, the heat absorbed by the water was found to be 5.555 kJ/s and in rectangular design, the heat absorbed by the water was 4.872 kJ/s. An experimental analysis conducted to validate the simulation by a rectangular Heat exchanger shows the amount of heat absorbed by the water is 4.87 kJ/s. In a study with variable water flow rate through the jacket, it is observed that heat absorbed by the water in conical heat exchanger is more than heat absorbed by the water in rectangular jacket within the flow rate of 4 l/min. and the heat absorbed by the water in rectangular heat exchanger is higher than conical heat exchanger with water flow rate above 4 l/min.
- Full Text:
- Date Issued: 2019
Critical success factors of South African construction companies
- Authors: Lombard, Daniel
- Date: 2019
- Subjects: Construction industry -- Planning -- South Africa , Construction industry -- Management Construction industry -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42229 , vital:36637
- Description: The aim of the study was to identify the driving forces of the South African construction industry for registered cidb Grade 9 companies. The next objective was to identify the critical success factors (CSF) that are required to be used by the forward-looking and pro-active cidb Grade 9 companies. The most important critical success factors were then highlighted to form a core group of CSFs for construction industry. From this core group of CSFs an attempt was then made to identify business strategies that can assist companies in gaining a competitive advantage in the construction industry of South Africa. The research was based on the problem statement from which the sub-questions and hypothesis were derived. The primary data was collected through a mixed method of quantitative and qualitative research. A ontological philosophy was used for the research to effectively collaborate with the mixed method of research used. The approach of the research was a mix of both inductive and deductive, as it pursued to identify the forces and factors dominating the construction industry. The study subsequently determined what business strategies best suit these results. The research questionnaire was distributed between senior managers of grade 9 cidb construction companies and found that the most eminent driving forces of the industry are political and government decision making, as well as economic conditions. The CSFs showed a clear indication of what the respondents perceived as the most important factors. Although there have been many advances in technology and processes over the years, the most important CSF for contractors are still the processes of bidding and tendering and the factors relating to these. The qualitative research portion of the study was an investigation on what business strategies were best related to the key driving forces and most important CSFs. Interviews were held with directors of cidb grade 9 construction companies. The themes that were identified from the analyses of the qualitative data were that business strategies relevant to differentiation, diversification, cost leadership or hybrid were seen as the most effective for construction companies. The bidding and tendering process is not merely the same process that it used to be. Frequent reviews of what the industry is going through have also become a major necessity. The research was limited to companies registered as grade 9 with the Construction Industry Development Board. The research is seen as valued as the construction industry is highly important towards the development of the economy of a country and the impact that it has on communities.
- Full Text:
- Date Issued: 2019
- Authors: Lombard, Daniel
- Date: 2019
- Subjects: Construction industry -- Planning -- South Africa , Construction industry -- Management Construction industry -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42229 , vital:36637
- Description: The aim of the study was to identify the driving forces of the South African construction industry for registered cidb Grade 9 companies. The next objective was to identify the critical success factors (CSF) that are required to be used by the forward-looking and pro-active cidb Grade 9 companies. The most important critical success factors were then highlighted to form a core group of CSFs for construction industry. From this core group of CSFs an attempt was then made to identify business strategies that can assist companies in gaining a competitive advantage in the construction industry of South Africa. The research was based on the problem statement from which the sub-questions and hypothesis were derived. The primary data was collected through a mixed method of quantitative and qualitative research. A ontological philosophy was used for the research to effectively collaborate with the mixed method of research used. The approach of the research was a mix of both inductive and deductive, as it pursued to identify the forces and factors dominating the construction industry. The study subsequently determined what business strategies best suit these results. The research questionnaire was distributed between senior managers of grade 9 cidb construction companies and found that the most eminent driving forces of the industry are political and government decision making, as well as economic conditions. The CSFs showed a clear indication of what the respondents perceived as the most important factors. Although there have been many advances in technology and processes over the years, the most important CSF for contractors are still the processes of bidding and tendering and the factors relating to these. The qualitative research portion of the study was an investigation on what business strategies were best related to the key driving forces and most important CSFs. Interviews were held with directors of cidb grade 9 construction companies. The themes that were identified from the analyses of the qualitative data were that business strategies relevant to differentiation, diversification, cost leadership or hybrid were seen as the most effective for construction companies. The bidding and tendering process is not merely the same process that it used to be. Frequent reviews of what the industry is going through have also become a major necessity. The research was limited to companies registered as grade 9 with the Construction Industry Development Board. The research is seen as valued as the construction industry is highly important towards the development of the economy of a country and the impact that it has on communities.
- Full Text:
- Date Issued: 2019
Damage recovery for robot controllers and simulators evolved using bootstrapped neuro-simulation
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
Design and Characterization of a 5 kw Xe-Lamp Solar Simulator
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
Determination of social, environmental and economic benefits for community participation in forestry in Mpumalanga, South Africa
- Long, Leo Searle, Chirwa, Paxie
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019