Variation in forage quality in subtropical thicket
- Nyembe, Khulisile Jacqueline
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Ureaplasma species in the placenta and histopathology associated with preterm birth
- Authors: Sprong, Kaitlin Elizabeth
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54128 , vital:46310
- Description: The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasma spp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalence of Ureaplasma urealyticum, Ureaplasma parvumand Mycoplasma hominisin the placenta and its role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasma spp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasma spp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasma spp. in the placenta and adverse maternal, obstetric and neonatal outcomes. iiiABSTRACTBackground The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasmaspp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalenceof Ureaplasmaurealyticum,UreaplasmaparvumandMycoplasmahominisin the placenta andits role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasmaspp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasmaspp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasmaspp. inthe placenta and adverse maternal, obstetric and neonatal outcomes. MethodsPlacentas were collected from patients presenting with preterm birth (n=100; 28-34 weeks gestational age) and term birth (n=20; >38 weeks) regardless of the APGAR score. Placentas were submitted for histopathology and used for detection of Ureaplasmaspp. by culture (U9 broth, MycoDuo kits;BioRad) and PCR (DNA was extracted from culture and homogenized placental tissue). Antibiotic susceptibility profiles of Ureaplasmaspp isolates were determined by the SIR Antibiogram kit (BioRad) and microbroth dilution method. Molecular mechanisms of resistance were ascertained by PCR amplification of target genes. Placentas were sent to National Health Laboratory Servicesfor routine histopathology. Next generation sequencing was performed on 16S rRNA amplicons from placental DNA for analysis of microbial diversity. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Sprong, Kaitlin Elizabeth
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54128 , vital:46310
- Description: The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasma spp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalence of Ureaplasma urealyticum, Ureaplasma parvumand Mycoplasma hominisin the placenta and its role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasma spp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasma spp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasma spp. in the placenta and adverse maternal, obstetric and neonatal outcomes. iiiABSTRACTBackground The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasmaspp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalenceof Ureaplasmaurealyticum,UreaplasmaparvumandMycoplasmahominisin the placenta andits role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasmaspp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasmaspp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasmaspp. inthe placenta and adverse maternal, obstetric and neonatal outcomes. MethodsPlacentas were collected from patients presenting with preterm birth (n=100; 28-34 weeks gestational age) and term birth (n=20; >38 weeks) regardless of the APGAR score. Placentas were submitted for histopathology and used for detection of Ureaplasmaspp. by culture (U9 broth, MycoDuo kits;BioRad) and PCR (DNA was extracted from culture and homogenized placental tissue). Antibiotic susceptibility profiles of Ureaplasmaspp isolates were determined by the SIR Antibiogram kit (BioRad) and microbroth dilution method. Molecular mechanisms of resistance were ascertained by PCR amplification of target genes. Placentas were sent to National Health Laboratory Servicesfor routine histopathology. Next generation sequencing was performed on 16S rRNA amplicons from placental DNA for analysis of microbial diversity. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
Upwelling over submarine canyons: an in-situ and modelling approach
- Authors: Rautenbach, Gustav
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Oceanography -- Research -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52078 , vital:43442
- Description: The iSimangaliso Wetland Park, located along the coastline of northern KwaZulu-Natal (KZN), hosts South Africa's only tropical coral reef system and is clustered with submarine canyons. These ecosystems support a flourishing diving and pelagic sportfishing industry in the area that contributes tens of millions of rand to the South African Gross Domestic Profit (GDP) annually as well as to provide income and job security for the majority of the local residents. Understanding the oceanographic dynamics, particularly upwelling events, will improve current knowledge of how the ecosystem works and may enhance conservation techniques. The upwelling events within the iSimangaliso Wetland Park results in the influx of cold and nutrient rich waters that supports biological productivity in the area. The complex oceanography, dominated by the Northern Agulhas Current and mesoscale eddies that stem from the Mozambique Channel and South East Madagascar Current (SEMC) is understudied and lacks understanding. This thesis aims to build upon the current knowledge of the upwelling events over the submarine canyons and the concurrent influence on the Mixed Layer Depth (MLD). At the submarine canyons, six anomalous cooling events were identified from surface and subsurface measurements extracted from the Operational Sea Surface Temperature and Ice Analysis (OSTIA) Sea Surface Temperature (SST) and from data collected using Underwater Temperature Recorders (UTRs) over a 12-month period. Depth-integrated lagged correlations showed a 2-to-7-hour lag period from the deep to shallow stations, suggesting that the anomalous cooling events are in fact upwelling events. Wind measurements from the Mbazwana Weather Station and snapshots of sea-level anomalies illustrated that the weaker and shorter upwelling events are driven either by alongshore wind stress or a cyclonic eddy event solely; whereas the stronger event was driven by the combination of both forcing mechanisms. An idealized canyon ocean model is used to interrogate the two forcing mechanisms more fully and showed that the most intense upwelling events are driven by the combined effect of upwelling-favourable alongshore wind stress and a cyclonic eddy which results in strong upward vertical velocity anomalies and the greatest shallowing (6.88 m) of the MLD. With the contribution of the in-situ measurements as a baseline study it is apparent that the idealised model does provide an improved understanding of the upwelling events and forcing mechanism over the submarine canyons within the iSimangaliso Wetland Park. , Thesis (MSc) -- Faculty of Science, Ocean Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Rautenbach, Gustav
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Oceanography -- Research -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52078 , vital:43442
- Description: The iSimangaliso Wetland Park, located along the coastline of northern KwaZulu-Natal (KZN), hosts South Africa's only tropical coral reef system and is clustered with submarine canyons. These ecosystems support a flourishing diving and pelagic sportfishing industry in the area that contributes tens of millions of rand to the South African Gross Domestic Profit (GDP) annually as well as to provide income and job security for the majority of the local residents. Understanding the oceanographic dynamics, particularly upwelling events, will improve current knowledge of how the ecosystem works and may enhance conservation techniques. The upwelling events within the iSimangaliso Wetland Park results in the influx of cold and nutrient rich waters that supports biological productivity in the area. The complex oceanography, dominated by the Northern Agulhas Current and mesoscale eddies that stem from the Mozambique Channel and South East Madagascar Current (SEMC) is understudied and lacks understanding. This thesis aims to build upon the current knowledge of the upwelling events over the submarine canyons and the concurrent influence on the Mixed Layer Depth (MLD). At the submarine canyons, six anomalous cooling events were identified from surface and subsurface measurements extracted from the Operational Sea Surface Temperature and Ice Analysis (OSTIA) Sea Surface Temperature (SST) and from data collected using Underwater Temperature Recorders (UTRs) over a 12-month period. Depth-integrated lagged correlations showed a 2-to-7-hour lag period from the deep to shallow stations, suggesting that the anomalous cooling events are in fact upwelling events. Wind measurements from the Mbazwana Weather Station and snapshots of sea-level anomalies illustrated that the weaker and shorter upwelling events are driven either by alongshore wind stress or a cyclonic eddy event solely; whereas the stronger event was driven by the combination of both forcing mechanisms. An idealized canyon ocean model is used to interrogate the two forcing mechanisms more fully and showed that the most intense upwelling events are driven by the combined effect of upwelling-favourable alongshore wind stress and a cyclonic eddy which results in strong upward vertical velocity anomalies and the greatest shallowing (6.88 m) of the MLD. With the contribution of the in-situ measurements as a baseline study it is apparent that the idealised model does provide an improved understanding of the upwelling events and forcing mechanism over the submarine canyons within the iSimangaliso Wetland Park. , Thesis (MSc) -- Faculty of Science, Ocean Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Thiazole derivatives as potential hiv-1 protease inhibitors
- Authors: Hlongwe, Zola
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Enzyme kinetics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52116 , vital:43427
- Description: Series of compounds were screened using Schrodinger suite (Maestro). The DFT calculations were used for geometry optimization of the ligands using the B3YLYP functional and 6-31G basis set, and these structures were used for docking studies. Maestro was used to predict the activity of thiazole derivatives against HIV-1 protease. The range of estimated inhibition constants for these thiazole derivatives (65 nM-5 μM) indicate moderate to weak activity against HIV-1 protease, given that the activity of current protease inhibitors is typically found have experimental inhibition constants around 0.1-2.0 nM. Twenty compounds were selected based on the docking results and they were synthesized and characterized by NMR, FT-IR and elemental analysis. The cytotoxicity studies were done at two different concentrations (100 μM and 10 μM), using the brine shrimp bioassay. All compounds were highly toxic at 100 μM, with the percentage mortality between 20 to 75%. Eight compounds were selected for the enzyme bioassay based on the results obtained from lower concentration (10 μM). In the enzyme inhibition studies, the profile of HIV-1 activity was done at different inhibitor concentrations (800 μM – 10 μM) by measuring the cleavage of the synthetic substrate (Abz-Thr-lle-PNO2Phe=Gln-Arg-NH2) at excitation wavelength of 345/490 nm using fluorescence. Ligands 5 (unsubstituted derivative), 7 (4-nitro derivative) and 16 (4-methoxy derivative) gave percentage inhibition of 39, 45 and 42%, and this activity was very low compared to the activity of the positive control ritonavir (85% enzyme inhibition). Ligands 8 (4-methoxy derivative) and 12 (4-methoxy derivative) gave enzyme inhibition of 70% and 75%. These results suggest that the presence of the methoxy substituents ii increases activity of these compounds against HIV-1 protease. Most of the compounds gave good IC50 values between 12.5-42.7 nM. The bromo-substituted ligand 7 gave the lowest IC50 (12.5 nM). Ligand 11 also gave a good IC50 value of 14.86 nM. The bromo-substituted derivatives showed to be very active compared to other types of thiazole derivatives. Enzyme kinetics were carried out to compare the inhibition constants obtained via computational modelling. Ligand 7 (4-methoxy derivatives) binds better in the active site of HIV-1 protease than other compounds in Class B, with Ki = 50 nM, Km = 23.8 Nm and Vmax = 83.3 nM/min. The unsubstituted (L5), 4-bromo (L7) and 4-nitro (L8) substituted compounds gave inhibition constants of 100 to 112 nM. The in vitro testing yielded higher activity than that determined in silico. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Hlongwe, Zola
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Enzyme kinetics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52116 , vital:43427
- Description: Series of compounds were screened using Schrodinger suite (Maestro). The DFT calculations were used for geometry optimization of the ligands using the B3YLYP functional and 6-31G basis set, and these structures were used for docking studies. Maestro was used to predict the activity of thiazole derivatives against HIV-1 protease. The range of estimated inhibition constants for these thiazole derivatives (65 nM-5 μM) indicate moderate to weak activity against HIV-1 protease, given that the activity of current protease inhibitors is typically found have experimental inhibition constants around 0.1-2.0 nM. Twenty compounds were selected based on the docking results and they were synthesized and characterized by NMR, FT-IR and elemental analysis. The cytotoxicity studies were done at two different concentrations (100 μM and 10 μM), using the brine shrimp bioassay. All compounds were highly toxic at 100 μM, with the percentage mortality between 20 to 75%. Eight compounds were selected for the enzyme bioassay based on the results obtained from lower concentration (10 μM). In the enzyme inhibition studies, the profile of HIV-1 activity was done at different inhibitor concentrations (800 μM – 10 μM) by measuring the cleavage of the synthetic substrate (Abz-Thr-lle-PNO2Phe=Gln-Arg-NH2) at excitation wavelength of 345/490 nm using fluorescence. Ligands 5 (unsubstituted derivative), 7 (4-nitro derivative) and 16 (4-methoxy derivative) gave percentage inhibition of 39, 45 and 42%, and this activity was very low compared to the activity of the positive control ritonavir (85% enzyme inhibition). Ligands 8 (4-methoxy derivative) and 12 (4-methoxy derivative) gave enzyme inhibition of 70% and 75%. These results suggest that the presence of the methoxy substituents ii increases activity of these compounds against HIV-1 protease. Most of the compounds gave good IC50 values between 12.5-42.7 nM. The bromo-substituted ligand 7 gave the lowest IC50 (12.5 nM). Ligand 11 also gave a good IC50 value of 14.86 nM. The bromo-substituted derivatives showed to be very active compared to other types of thiazole derivatives. Enzyme kinetics were carried out to compare the inhibition constants obtained via computational modelling. Ligand 7 (4-methoxy derivatives) binds better in the active site of HIV-1 protease than other compounds in Class B, with Ki = 50 nM, Km = 23.8 Nm and Vmax = 83.3 nM/min. The unsubstituted (L5), 4-bromo (L7) and 4-nitro (L8) substituted compounds gave inhibition constants of 100 to 112 nM. The in vitro testing yielded higher activity than that determined in silico. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
The use of psychometric test systems as a pre-selection tool for identifying successful harvesting machine operators
- Authors: Schwegman, Kylle
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55246 , vital:51102
- Description: A shift towards fully mechanized forest activities, such as harvesting and, more recently, silviculture, has occurred from the early 2 000’s. The reason for mechanizing these activities differs for each country, although for most countries there is concern relating to the health and safety of forest workers. With mechanization in harvesting, the forest worker has moved away from the physical intensity of having to fell, debranch, debark and cross-cut trees into logs using either an axe or chainsaw, to operating a machine. Studies revolving around the human element (operator) have been conducted specifically relating to the ergonomics of the machines and how operators may influence machine productivity. Results showed that due to the repetitive nature of the work, the operators are exposed to associated stresses for longer periods. Typical injuries associated to these kinds of stressors are whole body vibrations (WBVs), repetitive hand and arm movements, non-neutral body postures and manual lifting, which lead to musculoskeletal symptoms in the lower back, neck and shoulders. However, as machine technology improves so does the ergonomic conditions which are experienced by machine operators. Machine productivity can be influenced by various factors, with the most influential being tree volume. However, a recent study showed that over 40% of variation in machine productivity has been observed amongst different machine operators operating similar machines. The specific reason for these differences has yet to be determined. However, decision making, motivation, planning capacity, concentration, memory, motor coordination, pattern recognition, logic reasoning, and spatial perception are abilities that have been described as important for successful harvesting work. The pre-selection of operators using psychometric and cognitive tests is not new to forestry, although very little information is available relating to the aptitude test known as the Vienna test system as well as the best possible demographic associated with successful harvesting operators. The overall aim of this study was to determine whether the high variation found amongst harvesting machine operators could be reduced initially through a preselection process which involves the use of aptitude tests (Vienna Test System) and demographic questionnaires. A study was implemented in Zululand, South Africa, testing whether there were significant productivity differences between nine machine operators. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Schwegman, Kylle
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55246 , vital:51102
- Description: A shift towards fully mechanized forest activities, such as harvesting and, more recently, silviculture, has occurred from the early 2 000’s. The reason for mechanizing these activities differs for each country, although for most countries there is concern relating to the health and safety of forest workers. With mechanization in harvesting, the forest worker has moved away from the physical intensity of having to fell, debranch, debark and cross-cut trees into logs using either an axe or chainsaw, to operating a machine. Studies revolving around the human element (operator) have been conducted specifically relating to the ergonomics of the machines and how operators may influence machine productivity. Results showed that due to the repetitive nature of the work, the operators are exposed to associated stresses for longer periods. Typical injuries associated to these kinds of stressors are whole body vibrations (WBVs), repetitive hand and arm movements, non-neutral body postures and manual lifting, which lead to musculoskeletal symptoms in the lower back, neck and shoulders. However, as machine technology improves so does the ergonomic conditions which are experienced by machine operators. Machine productivity can be influenced by various factors, with the most influential being tree volume. However, a recent study showed that over 40% of variation in machine productivity has been observed amongst different machine operators operating similar machines. The specific reason for these differences has yet to be determined. However, decision making, motivation, planning capacity, concentration, memory, motor coordination, pattern recognition, logic reasoning, and spatial perception are abilities that have been described as important for successful harvesting work. The pre-selection of operators using psychometric and cognitive tests is not new to forestry, although very little information is available relating to the aptitude test known as the Vienna test system as well as the best possible demographic associated with successful harvesting operators. The overall aim of this study was to determine whether the high variation found amongst harvesting machine operators could be reduced initially through a preselection process which involves the use of aptitude tests (Vienna Test System) and demographic questionnaires. A study was implemented in Zululand, South Africa, testing whether there were significant productivity differences between nine machine operators. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2022
- Full Text:
- Date Issued: 2022-04
The use of ambient seismic noise to investigate internal changes in a tailings storage facility and to image the subsurface geology in the Cradock area of the Eastern Cape
- Authors: Kunjwa, Thulisile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53642 , vital:45690
- Description: Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. Recent advancements in ambient seismic noise techniques have the potential to provide new methods for subsurface imaging and monitoring. The ambient noise data processing procedure divides into four principal phases: (1) single station data preparation, (2) cross-correlation and temporal stacking, (3) measurement of dispersion curves and (4) inversion of dispersion curves to obtain 1-D shear wave profiles and computation of 2-D shear wave velocity cross-section. The purpose of this study is to investigate whether ambient seismic noise can be used to image and detect internal changes within a mine tailings dam wall and to image the subsurface geology of part of the Eastern Cape Karoo near Cradock. In the first experiment, the investigation consisted of continuous ambient noise data recordings over a period of 3 days with 20 three-component short period geophones. The geophones were deployed over a survey wall of roughly 100 m in length at the Harmony Gold mine tailings dam in Welkom. In the second experiment, the investigation consisted of data recordings over a period of 35 days. The geophones were deployed in Cradock. The first phase of the data processing procedure included de-trending, de-meaning and band-pass filtering the data. This was done to ensure that any long period trends associated with instrument glitches are removed from the data. A spectrogram was then computed to view the spectrum of frequencies in the signal and to check if the filter that was designed was able to cut off the unwanted frequencies. The horizontal and vertical components of the ambient noise data were cross-correlated and picked between sensor pairs to create surface wave dispersion curves. Subsequently, the dispersion curves were inverted to estimate the shear wave velocity of the dam wall and subsurface as a function of depth. The computed cross sections of shear wave velocity indicated a low-velocity zone between 2 and 10 m below the surface on the dam wall, this suggested that the phreatic surface is much closer to surface in this area. In the second experiment, the interpolated shear wave velocity profiles indicated that there is a layer of low velocity zone between depths 250 to 300 m below the surface. The cross-correlations were also used to compute group velocity maps from periods 1.5 seconds to 30 seconds. The group velocity maps showed various high and low velocity anomalies. The high velocity zones observed on the eastern section of the map were interpreted as evidence of dolerite intrusions. The low velocity zones observed in the western and southern sections of the map interpreted as Karoo sediments that belong to the Adelaide Subgroup which is dominated by mudstones. , Thesis (MSc) -- Faculty of Science, Department of Geosciences (Geology and Geography), 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Kunjwa, Thulisile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53642 , vital:45690
- Description: Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. Recent advancements in ambient seismic noise techniques have the potential to provide new methods for subsurface imaging and monitoring. The ambient noise data processing procedure divides into four principal phases: (1) single station data preparation, (2) cross-correlation and temporal stacking, (3) measurement of dispersion curves and (4) inversion of dispersion curves to obtain 1-D shear wave profiles and computation of 2-D shear wave velocity cross-section. The purpose of this study is to investigate whether ambient seismic noise can be used to image and detect internal changes within a mine tailings dam wall and to image the subsurface geology of part of the Eastern Cape Karoo near Cradock. In the first experiment, the investigation consisted of continuous ambient noise data recordings over a period of 3 days with 20 three-component short period geophones. The geophones were deployed over a survey wall of roughly 100 m in length at the Harmony Gold mine tailings dam in Welkom. In the second experiment, the investigation consisted of data recordings over a period of 35 days. The geophones were deployed in Cradock. The first phase of the data processing procedure included de-trending, de-meaning and band-pass filtering the data. This was done to ensure that any long period trends associated with instrument glitches are removed from the data. A spectrogram was then computed to view the spectrum of frequencies in the signal and to check if the filter that was designed was able to cut off the unwanted frequencies. The horizontal and vertical components of the ambient noise data were cross-correlated and picked between sensor pairs to create surface wave dispersion curves. Subsequently, the dispersion curves were inverted to estimate the shear wave velocity of the dam wall and subsurface as a function of depth. The computed cross sections of shear wave velocity indicated a low-velocity zone between 2 and 10 m below the surface on the dam wall, this suggested that the phreatic surface is much closer to surface in this area. In the second experiment, the interpolated shear wave velocity profiles indicated that there is a layer of low velocity zone between depths 250 to 300 m below the surface. The cross-correlations were also used to compute group velocity maps from periods 1.5 seconds to 30 seconds. The group velocity maps showed various high and low velocity anomalies. The high velocity zones observed on the eastern section of the map were interpreted as evidence of dolerite intrusions. The low velocity zones observed in the western and southern sections of the map interpreted as Karoo sediments that belong to the Adelaide Subgroup which is dominated by mudstones. , Thesis (MSc) -- Faculty of Science, Department of Geosciences (Geology and Geography), 2021
- Full Text:
- Date Issued: 2021-12
The use of a rapid incineration field test for determining soil organic carbon in the Southern Cape Region
- Authors: Ackhurst, Albert Arthur
- Date: 2014-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53336 , vital:45135
- Description: Knowledge of soil organic carbon levels is important both for agricultural effectiveness and soil carbon sequestration accounting, especially against the backdrop of increased climate change impacts and pressure on food production landscapes. However, current methods for soil carbon determination are expensive, energy intensive, time consuming and potentially hazardous leading to a call for alternative methods, which should be cheap, fast, simple, accurate, safe and usable where resources and soil analysis laboratories are limited. To this end the student invented a novel rapid incineration field test (RIFT) for determining soil organic carbon and tested its validity in this study. This method incorporates principles found in dry combustion as well as loss-on-ignition and quantifying organic carbon through gravimetric analysis. In order to illustrate effectiveness and accuracy it was necessary to correlate RIFT with a reference method, in this instance dry combustion with a Leco device as well as another commonly used indirect method namely the Walkley-Black wet chemical oxidation method. Samples from eleven soil forms were collected from the Southern Cape region and they were subjected to the three testing methods. It was found that RIFT is indeed as effective and in 72% of the soil forms even more effective than Walkley-Black. Furthermore, it was ascertained whether the accuracy of RIFT can be improved by correcting for clay content. The correlation of RIFT with clay % was not very significant and clay % as a variable was therefore not used in this study to obtain further refinement of RIFT predictions. Another finding was also that RIFT illustrated less variability than both the Leco and Walkley-Black methods. Lastly it was ascertained that the RIFT device and methodology is indeed cost effective, energy efficient, fast and safe in terms of the need to use potentially hazardous chemicals. , Thesis (MA) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2014-12
- Authors: Ackhurst, Albert Arthur
- Date: 2014-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53336 , vital:45135
- Description: Knowledge of soil organic carbon levels is important both for agricultural effectiveness and soil carbon sequestration accounting, especially against the backdrop of increased climate change impacts and pressure on food production landscapes. However, current methods for soil carbon determination are expensive, energy intensive, time consuming and potentially hazardous leading to a call for alternative methods, which should be cheap, fast, simple, accurate, safe and usable where resources and soil analysis laboratories are limited. To this end the student invented a novel rapid incineration field test (RIFT) for determining soil organic carbon and tested its validity in this study. This method incorporates principles found in dry combustion as well as loss-on-ignition and quantifying organic carbon through gravimetric analysis. In order to illustrate effectiveness and accuracy it was necessary to correlate RIFT with a reference method, in this instance dry combustion with a Leco device as well as another commonly used indirect method namely the Walkley-Black wet chemical oxidation method. Samples from eleven soil forms were collected from the Southern Cape region and they were subjected to the three testing methods. It was found that RIFT is indeed as effective and in 72% of the soil forms even more effective than Walkley-Black. Furthermore, it was ascertained whether the accuracy of RIFT can be improved by correcting for clay content. The correlation of RIFT with clay % was not very significant and clay % as a variable was therefore not used in this study to obtain further refinement of RIFT predictions. Another finding was also that RIFT illustrated less variability than both the Leco and Walkley-Black methods. Lastly it was ascertained that the RIFT device and methodology is indeed cost effective, energy efficient, fast and safe in terms of the need to use potentially hazardous chemicals. , Thesis (MA) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2014-12
The synthesis, empirical and theoretical studies of various (N→B) diarylborinate esters
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
The synthesis of anastrazole intermediates using continuous flow systems
- Authors: Tanyi, Sam Tambi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54116 , vital:46304
- Description: In this study, the continuous flow synthesis of anastrozole intermediates were investigated using mesitylene as starting material. Anastrozole is an important drug used for the treatment of breast cancer. In the first step, mesitylene was brominated using N-bromosuccinimide to obtain 3,5-bis(bromomethyl)toluene. Selectivity became an issue due to the formation of two by-products; namely 1,3,5-tris(bromomethyl) benzene (the tribrominated by-product) and 1-(bromomethyl)-3,5-dimethylbenzene (the monobrominated by-product). Since the reaction parameters can be more precisely controlled in flow chemistry systems, we were able to optimize the formation the desired product 3,5-bis(bromomethyl)toluene. The reaction was initially optimized ina 15μLChemtrix glass micro reactor resulting in 100%conversion with 95%selectivity towards the desired product 3,5-bis(bromomethyl)toluenein 15 seconds, with a throughput of 0.006 g/h. The reaction was then scaled up in a 1.7 mLLTF reactor, equally yielding 100%conversion with 95%selectivityin 4minutes, with a throughput of2.01g/h. The bromination of mesitylene was also attempted in a homemade photochemical reactor consisting of a 3.02 polytetrafluoroethylene coil reactor and BLE-6T365 UV lamp. In this photochemical reactor, although 100%conversionwas again obtained only75%selectivity was achieved in 20minutes, with a throughput of 0.025g/h. This drop in selectivity was attributed to poorer mixing in the larger polytetrafluoroethylene coil reactor and possibly insufficient light penetration. The next step, involving the cyanation of 3,5-bis(bromomethyl)toluene to obtain 2,2'-(5-methyl-1,3-phenylene) diacetonitrilegave 100%conversion in 1 minute at 190 °C in a 1.7 mLLTFreactor, with a throughput of 5.2g/h. The subsequent methylation of 3,5-bis(cyanomethyl)toluene to obtain3,5-bis(1-cyano-1-methylethyl) toluene was investigated using a1mLpolytetrafluoroethylenecoil reactor, ultimatelyachieving99%conversionat40 °Cin 8minutes, with a throughput of 0.045g/h. Next, the bromination of3,5-bis(1-cyano-1-methylethyl)toluene using N-bromosuccinimideto yield 2,2'-(5-bromomethyl-1,3-phenylene)di(2-methyl propionitrile) gave 100%conversion at 120 °C in 4 minutes, with a throughput of 0.35g/h. Lastly, the multistep synthesis of 3,5-bis(cyanomethyl)toluene was done in two integrated 1.7 mLLTF reactors, using the predetermined optimum conditions to achieve 94%conversion towards 3,5-bis(cyanomethyl)toluene with a total r , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Tanyi, Sam Tambi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54116 , vital:46304
- Description: In this study, the continuous flow synthesis of anastrozole intermediates were investigated using mesitylene as starting material. Anastrozole is an important drug used for the treatment of breast cancer. In the first step, mesitylene was brominated using N-bromosuccinimide to obtain 3,5-bis(bromomethyl)toluene. Selectivity became an issue due to the formation of two by-products; namely 1,3,5-tris(bromomethyl) benzene (the tribrominated by-product) and 1-(bromomethyl)-3,5-dimethylbenzene (the monobrominated by-product). Since the reaction parameters can be more precisely controlled in flow chemistry systems, we were able to optimize the formation the desired product 3,5-bis(bromomethyl)toluene. The reaction was initially optimized ina 15μLChemtrix glass micro reactor resulting in 100%conversion with 95%selectivity towards the desired product 3,5-bis(bromomethyl)toluenein 15 seconds, with a throughput of 0.006 g/h. The reaction was then scaled up in a 1.7 mLLTF reactor, equally yielding 100%conversion with 95%selectivityin 4minutes, with a throughput of2.01g/h. The bromination of mesitylene was also attempted in a homemade photochemical reactor consisting of a 3.02 polytetrafluoroethylene coil reactor and BLE-6T365 UV lamp. In this photochemical reactor, although 100%conversionwas again obtained only75%selectivity was achieved in 20minutes, with a throughput of 0.025g/h. This drop in selectivity was attributed to poorer mixing in the larger polytetrafluoroethylene coil reactor and possibly insufficient light penetration. The next step, involving the cyanation of 3,5-bis(bromomethyl)toluene to obtain 2,2'-(5-methyl-1,3-phenylene) diacetonitrilegave 100%conversion in 1 minute at 190 °C in a 1.7 mLLTFreactor, with a throughput of 5.2g/h. The subsequent methylation of 3,5-bis(cyanomethyl)toluene to obtain3,5-bis(1-cyano-1-methylethyl) toluene was investigated using a1mLpolytetrafluoroethylenecoil reactor, ultimatelyachieving99%conversionat40 °Cin 8minutes, with a throughput of 0.045g/h. Next, the bromination of3,5-bis(1-cyano-1-methylethyl)toluene using N-bromosuccinimideto yield 2,2'-(5-bromomethyl-1,3-phenylene)di(2-methyl propionitrile) gave 100%conversion at 120 °C in 4 minutes, with a throughput of 0.35g/h. Lastly, the multistep synthesis of 3,5-bis(cyanomethyl)toluene was done in two integrated 1.7 mLLTF reactors, using the predetermined optimum conditions to achieve 94%conversion towards 3,5-bis(cyanomethyl)toluene with a total r , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
The impact of transformed landscapes on the resource selection and occupancy of specialized browsing species in a lowland fynbos and renosterveld ecosystem
- Swanepoel, Hermanus Izak Johannes
- Authors: Swanepoel, Hermanus Izak Johannes
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54132 , vital:46308
- Description: Human activities have dramatically transformed the natural environment over the last century. In most cases these activities have resulted in the destruction and fragmentation of habitats. However, in some areas the transformation of landscapes through agriculture have created novel habitats which could benefit some species. The effect of these transformed landscapes on the resource selection and occupancy of antelope species in different vegetation types such as fynbos and renosterveld are still understudied. In order to investigate this,we conducted a study in the Overberg region of the Western Cape, South Africa. We studied theoccupancy and habitat useof five specialist browsing species (Tragelaphus scriptus sylvaticus(bushbuck), Rhaphicerus melanotis(cape grysbok), Sylvicapra grimmia(common duiker), Palea Capreolus(grey rhebok) and Rhaphicerus campestris(steenbok)) within a transformed landscape. We collected speciesdetection/ non-detectionand presence/ absence data using camera traps and road strip counts.Usinga single season, single species occupancy framework as a surrogate for habitat usewedeterminedhow transformed landscapes affected their occupancy. Using aniche factor analysis and resource selection functions wedetermine how transformed landscapes affected the resource selectionof these species. Our results from the resource selection analysis indicated that steenbok, grey rhebok, andcommon duiker included crops such as wheat and planted pastures in their resource selection while also including natural vegetation. Cape grysbok and bushbuck selected predominantly for natural vegetation areas such as critical biodiversity areas and ecological support areas while also including some crops in their resource selection. Our results from the occupancy analysis indicatedthat steenbok, grey rhebok and common duiker had a higher occupancy in the transformed landscape than in the natural landscape. Bushbuck and Cape grysbok showed little to no difference in their occupancy between land use types. The insight provided by our results will allow practitioners to maximise the potentialof these mosaic landscape in the Overberg for mammal conservation.The study also provides a baseline from which further research and monitoring programs can be developed to further understand the dynamics of this landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Swanepoel, Hermanus Izak Johannes
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54132 , vital:46308
- Description: Human activities have dramatically transformed the natural environment over the last century. In most cases these activities have resulted in the destruction and fragmentation of habitats. However, in some areas the transformation of landscapes through agriculture have created novel habitats which could benefit some species. The effect of these transformed landscapes on the resource selection and occupancy of antelope species in different vegetation types such as fynbos and renosterveld are still understudied. In order to investigate this,we conducted a study in the Overberg region of the Western Cape, South Africa. We studied theoccupancy and habitat useof five specialist browsing species (Tragelaphus scriptus sylvaticus(bushbuck), Rhaphicerus melanotis(cape grysbok), Sylvicapra grimmia(common duiker), Palea Capreolus(grey rhebok) and Rhaphicerus campestris(steenbok)) within a transformed landscape. We collected speciesdetection/ non-detectionand presence/ absence data using camera traps and road strip counts.Usinga single season, single species occupancy framework as a surrogate for habitat usewedeterminedhow transformed landscapes affected their occupancy. Using aniche factor analysis and resource selection functions wedetermine how transformed landscapes affected the resource selectionof these species. Our results from the resource selection analysis indicated that steenbok, grey rhebok, andcommon duiker included crops such as wheat and planted pastures in their resource selection while also including natural vegetation. Cape grysbok and bushbuck selected predominantly for natural vegetation areas such as critical biodiversity areas and ecological support areas while also including some crops in their resource selection. Our results from the occupancy analysis indicatedthat steenbok, grey rhebok and common duiker had a higher occupancy in the transformed landscape than in the natural landscape. Bushbuck and Cape grysbok showed little to no difference in their occupancy between land use types. The insight provided by our results will allow practitioners to maximise the potentialof these mosaic landscape in the Overberg for mammal conservation.The study also provides a baseline from which further research and monitoring programs can be developed to further understand the dynamics of this landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
The feeding ecology and habitat selection of small antelopes in the Overberg Renosterveld, Western Cape
- Authors: Jansen van Vuuren, Amauréé
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fynbos ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52014 , vital:43436
- Description: Human impacts have altered natural ecosystems which required species to become resilient in order to survive the anthropogenic landscape. The study area is located in the highly fragmented Overberg area in the Western Cape of South Africa. The high degree of fragmentation of the area is as a result of the nutrient rich soils and favourable topography which makes the area highly suitable for agricultural practices. The agriculture practiced in the area is mainly grain crops and livestock farming and the remaining patches of natural vegetation consist of Fynbos and Renosterveld vegetation. The patches of Fynbos and Renosterveld vegetation acts as movement corridors to allow species movement through the anthropogenic landscape. The anthropogenic landscape requires species to be resilient and to adapt to a novel habitat which poses new threats as well as new resources. The aim of the study is to investigate the effect of landscape transformation, resulting from agricultural practices, on the feeding and behavioural dynamics of five small specialist browser species in a fragmented lowland Fynbos and Renosterveld system. The objectives were to determine the forage preferences of each of the five specialist browser species and to determine which site-specific characteristics, drive the seasonal habitat use of the five specialist browser species. The five specialist browser species were bushbuck (Tragelaphus sylvaticus), Cape grysbok (Rhaphicerus melanotis), common duiker (Sylvicapra grimmia), grey rhebok (Pelea capreolus) and steenbok (Rhaphicerus campestris). To determine the dietary selection of the five specialist browser species we collected dung samples and performed a histological analysis on the dung samples. To determine the habitat use of the five specialist browser species we used an occupancy analysis framework on camera trap data collected on each of the species. Some species appeared more dependent on the food resources from the anthropogenic landscape and spent more time in the crops but required close by cover of natural vegetation. Others appeared more dependent on the remaining pockets of natural vegetation for food resources and spent more time in the natural vegetation. These species would occasionally move into the crops to utilise the food resources. Both the anthropogenic as well as the natural landscape contributed to the diets of all of the species. These species have been resilient to changes in the landscape and appear to be benefiting from the resources presented in the novel landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Jansen van Vuuren, Amauréé
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fynbos ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52014 , vital:43436
- Description: Human impacts have altered natural ecosystems which required species to become resilient in order to survive the anthropogenic landscape. The study area is located in the highly fragmented Overberg area in the Western Cape of South Africa. The high degree of fragmentation of the area is as a result of the nutrient rich soils and favourable topography which makes the area highly suitable for agricultural practices. The agriculture practiced in the area is mainly grain crops and livestock farming and the remaining patches of natural vegetation consist of Fynbos and Renosterveld vegetation. The patches of Fynbos and Renosterveld vegetation acts as movement corridors to allow species movement through the anthropogenic landscape. The anthropogenic landscape requires species to be resilient and to adapt to a novel habitat which poses new threats as well as new resources. The aim of the study is to investigate the effect of landscape transformation, resulting from agricultural practices, on the feeding and behavioural dynamics of five small specialist browser species in a fragmented lowland Fynbos and Renosterveld system. The objectives were to determine the forage preferences of each of the five specialist browser species and to determine which site-specific characteristics, drive the seasonal habitat use of the five specialist browser species. The five specialist browser species were bushbuck (Tragelaphus sylvaticus), Cape grysbok (Rhaphicerus melanotis), common duiker (Sylvicapra grimmia), grey rhebok (Pelea capreolus) and steenbok (Rhaphicerus campestris). To determine the dietary selection of the five specialist browser species we collected dung samples and performed a histological analysis on the dung samples. To determine the habitat use of the five specialist browser species we used an occupancy analysis framework on camera trap data collected on each of the species. Some species appeared more dependent on the food resources from the anthropogenic landscape and spent more time in the crops but required close by cover of natural vegetation. Others appeared more dependent on the remaining pockets of natural vegetation for food resources and spent more time in the natural vegetation. These species would occasionally move into the crops to utilise the food resources. Both the anthropogenic as well as the natural landscape contributed to the diets of all of the species. These species have been resilient to changes in the landscape and appear to be benefiting from the resources presented in the novel landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
The effect of silicon on palladium migration in pyrolytic carbon and graphite
- Authors: Downey, Justin Michael
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53665 , vital:45684
- Description: The pebble-bed reactor (PBR) is a graphite-moderated, gas-cooled high temperature nuclear reactor design and it is one of six nuclear reactor concepts included in the Generation IV initiative. Pebble-bed reactors use spherical fuel elements (called pebbles) which consist of pyrolytic graphite (which acts as the moderator) and contain thousands of micro-fuel particles called tristructural isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as U235 in oxide or carbide form) surrounded by a carbon buffer layer, a pyrolytic carbon (PyC) layer, a silicon carbide (SiC) ceramic layer for structural integrity and metallic fission product containment, and an outer PyC layer. The PBR is claimed to be a passively safe design. The commercial development of the first pebble bed reactor was that of the German AVR reactor (German: Arbeitsgemeinschaft Versuchsreaktor) developed during the 1960s. The AVR design was later updated and marketed by a company called HTR. In 1999 the South African electricity company ESKOM obtained the right to access the HTR engineering database that included details of the Siemens/Interatom HTR-Module design. ESKOM worked with HTR on a new design and dubbed it the pebble bed modular reactor (PBMR). The PBMR Co. Ltd. was formed in 1999 and mandated to license and build PBMR reactors. One of the safety considerations which emerged from research is that of metal fission product release from the TRISO fuel particles. Ag110m is a radioactive metallic fission product found to have been released from intact TRISO particles. The release of this Ag isotope is of particular concern because it is highly gamma active and has a half-life of approximately 250 days, resulting in unsafe environments for maintenance workers of PBRs. During the past four decades, many different mechanisms for Ag transport in SiC and release from TRISO particles have been proposed. A promising more recent mechanism suggests that the metallic fission product palladium (Pd) plays a significant role in the transport and release of Ag from intact TRISO particles. In this mechanism Ag transport in irradiated TRISO particle fuel takes place in the presence of the fission product Pd. The Pd reacts with the SiC layer and penetrates the SiC layer along grain boundaries to form a silicide layer which provides a rapid diffusion path for Ag in the SiC. The presence of thin silicide layers in irradiated TRISO particles was subsequently confirmed. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Downey, Justin Michael
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53665 , vital:45684
- Description: The pebble-bed reactor (PBR) is a graphite-moderated, gas-cooled high temperature nuclear reactor design and it is one of six nuclear reactor concepts included in the Generation IV initiative. Pebble-bed reactors use spherical fuel elements (called pebbles) which consist of pyrolytic graphite (which acts as the moderator) and contain thousands of micro-fuel particles called tristructural isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as U235 in oxide or carbide form) surrounded by a carbon buffer layer, a pyrolytic carbon (PyC) layer, a silicon carbide (SiC) ceramic layer for structural integrity and metallic fission product containment, and an outer PyC layer. The PBR is claimed to be a passively safe design. The commercial development of the first pebble bed reactor was that of the German AVR reactor (German: Arbeitsgemeinschaft Versuchsreaktor) developed during the 1960s. The AVR design was later updated and marketed by a company called HTR. In 1999 the South African electricity company ESKOM obtained the right to access the HTR engineering database that included details of the Siemens/Interatom HTR-Module design. ESKOM worked with HTR on a new design and dubbed it the pebble bed modular reactor (PBMR). The PBMR Co. Ltd. was formed in 1999 and mandated to license and build PBMR reactors. One of the safety considerations which emerged from research is that of metal fission product release from the TRISO fuel particles. Ag110m is a radioactive metallic fission product found to have been released from intact TRISO particles. The release of this Ag isotope is of particular concern because it is highly gamma active and has a half-life of approximately 250 days, resulting in unsafe environments for maintenance workers of PBRs. During the past four decades, many different mechanisms for Ag transport in SiC and release from TRISO particles have been proposed. A promising more recent mechanism suggests that the metallic fission product palladium (Pd) plays a significant role in the transport and release of Ag from intact TRISO particles. In this mechanism Ag transport in irradiated TRISO particle fuel takes place in the presence of the fission product Pd. The Pd reacts with the SiC layer and penetrates the SiC layer along grain boundaries to form a silicide layer which provides a rapid diffusion path for Ag in the SiC. The presence of thin silicide layers in irradiated TRISO particles was subsequently confirmed. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
The effect of laundering on the physical and thermal properties of phase change textile materials
- Authors: Scheepers, Ricardo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Textile chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52038 , vital:43443
- Description: Phase change materials (PCMs) have been incorporated into clothing and textiles to provide added value in terms of thermoregulation and thus added comfort to the wearer in extreme weather conditions and sporting activities. Since clothing is laundered many times during the service life of the textile, the effects of simulated domestic laundering on the physical and thermal properties of a non-woven textile which contains PCMs were investigated. The thermal properties, such as the thermal degradation, melting, evaporation and crystallisation were measured by the TGA and DSC analytical techniques. The physical properties, such as the microcapsule size distribution, and the microcapsule morphologies of the PCM microcapsules, were measured by the SEM and Raman analytical techniques. The main objectives of this study were to determine the effect of repeated laundering at different wash temperatures on the mass loss, enthalpy, and physical changes in PCM. Thermal degradation as determined by TGA thermograms was found to be higher at a wash temperature of 60°C relative to that of a wash temperature at 30°C, the mass loss being 4.6% more at 60°C than at 30°C. This was asserted to physical changes such as size and shape of the PCM microcapsules as evident in SEM images. The SEM images showed broken and collapsed PCM microcapsules in the web and around the fibre, indicating evaporation of the thermoregulating content of the PCM. It was found that the heat capacity of the sample washed at 60°C was much lower than that of the unwashed sample, the difference being approximately 50% in terms of the latent heat capacity as determined by DSC thermograms. This implies that the latent heat effectiveness of the PCM has decreased significantly. The physical properties of the PCM such as the intermolecular interaction, the intensity and width of peaks, polarisation, degree of crystallinity and the orientation changed as illustrated in the Raman analysis. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Scheepers, Ricardo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Textile chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52038 , vital:43443
- Description: Phase change materials (PCMs) have been incorporated into clothing and textiles to provide added value in terms of thermoregulation and thus added comfort to the wearer in extreme weather conditions and sporting activities. Since clothing is laundered many times during the service life of the textile, the effects of simulated domestic laundering on the physical and thermal properties of a non-woven textile which contains PCMs were investigated. The thermal properties, such as the thermal degradation, melting, evaporation and crystallisation were measured by the TGA and DSC analytical techniques. The physical properties, such as the microcapsule size distribution, and the microcapsule morphologies of the PCM microcapsules, were measured by the SEM and Raman analytical techniques. The main objectives of this study were to determine the effect of repeated laundering at different wash temperatures on the mass loss, enthalpy, and physical changes in PCM. Thermal degradation as determined by TGA thermograms was found to be higher at a wash temperature of 60°C relative to that of a wash temperature at 30°C, the mass loss being 4.6% more at 60°C than at 30°C. This was asserted to physical changes such as size and shape of the PCM microcapsules as evident in SEM images. The SEM images showed broken and collapsed PCM microcapsules in the web and around the fibre, indicating evaporation of the thermoregulating content of the PCM. It was found that the heat capacity of the sample washed at 60°C was much lower than that of the unwashed sample, the difference being approximately 50% in terms of the latent heat capacity as determined by DSC thermograms. This implies that the latent heat effectiveness of the PCM has decreased significantly. The physical properties of the PCM such as the intermolecular interaction, the intensity and width of peaks, polarisation, degree of crystallinity and the orientation changed as illustrated in the Raman analysis. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
The co-evolution of Africa’s eastern margin and its primate fauna: implications for hominin evolution
- Authors: Mambalu, Philasande
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59755 , vital:62418
- Description: I investigated potential links between the diversification of African primate lineages and the physical evolution of the continent. I compared published phylogenetic trees based on mitochondrial and nuclear DNA for five clades: (a) Lorisoidea (galagos and pottos); (b) arboreal guenon monkeys (Cercopithecus and its allies); (c) living apes (including humans); (d) Papionini (baboons); and (e) savanna or “vervet” monkeys (Chlorocebus). I compared primate divergence dates with the ages of tectonic events, patterns of climatic change, and their palaeo-vegetational consequences. Based on present primate distributions, I estimated likely geographic locations of the divergence events. Finally, I compared the phylogenetic patterns of the primate clades with hominin evolutionary scenarios. Phylogenetic comparisons indicated three time periods when rates of speciation increased across the five primate clades: the Eocene – Oligocene transition (34 – 32 Ma); the mid-late Miocene (10 – 5 Ma); and the Pliocene – Pleistocene transition (2.7 – 2.3 Ma). Concentrated bursts of lineage splitting indicate a broadscale causal relationship between environmental change and lineage divergence. Human evolution followed similar biogeographic patterns to those of other primate clades. Tectonic events, climatic changes and palaeo-vegetational shifts are intimately connected, and have synergistic effects on biotic diversity. Tectonic events influence climatic change through their effects on oceanic circulation, planetary temperatures and rainfall patterns. Additionally, tectonic uplift and erosion may create geographic barriers to organismal dispersal across the continent, increasing the likelihood of geographic separation of populations and speciation. Recently evolved primate species show high levels of hybridisation for several generations after their initial divergence. Genus Homo generated ~10 species over 2.5 Ma. The emergence of these taxa likely involved substantial hybridisation, as demonstrated by the presence of Neanderthal genes within the H. sapiens genome. I suggest that this hybridisation contributed to the difficulties palaeoanthropologists often experience in distinguishing fossil hominin taxa. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Mambalu, Philasande
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59755 , vital:62418
- Description: I investigated potential links between the diversification of African primate lineages and the physical evolution of the continent. I compared published phylogenetic trees based on mitochondrial and nuclear DNA for five clades: (a) Lorisoidea (galagos and pottos); (b) arboreal guenon monkeys (Cercopithecus and its allies); (c) living apes (including humans); (d) Papionini (baboons); and (e) savanna or “vervet” monkeys (Chlorocebus). I compared primate divergence dates with the ages of tectonic events, patterns of climatic change, and their palaeo-vegetational consequences. Based on present primate distributions, I estimated likely geographic locations of the divergence events. Finally, I compared the phylogenetic patterns of the primate clades with hominin evolutionary scenarios. Phylogenetic comparisons indicated three time periods when rates of speciation increased across the five primate clades: the Eocene – Oligocene transition (34 – 32 Ma); the mid-late Miocene (10 – 5 Ma); and the Pliocene – Pleistocene transition (2.7 – 2.3 Ma). Concentrated bursts of lineage splitting indicate a broadscale causal relationship between environmental change and lineage divergence. Human evolution followed similar biogeographic patterns to those of other primate clades. Tectonic events, climatic changes and palaeo-vegetational shifts are intimately connected, and have synergistic effects on biotic diversity. Tectonic events influence climatic change through their effects on oceanic circulation, planetary temperatures and rainfall patterns. Additionally, tectonic uplift and erosion may create geographic barriers to organismal dispersal across the continent, increasing the likelihood of geographic separation of populations and speciation. Recently evolved primate species show high levels of hybridisation for several generations after their initial divergence. Genus Homo generated ~10 species over 2.5 Ma. The emergence of these taxa likely involved substantial hybridisation, as demonstrated by the presence of Neanderthal genes within the H. sapiens genome. I suggest that this hybridisation contributed to the difficulties palaeoanthropologists often experience in distinguishing fossil hominin taxa. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
The aesthetics of hegemony: a speculative design proposal exploring the convergence of surveillance capitalism and brain-computer interface technologies in the future
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
Testing alternative Pinus species and hybrids for the South African structural pole market
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Synthesis of coumarin based fluorescent chemosensors for the detection of metal ions.
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Synthesis and characterization of iron doped sodium and potassium titanates using the pechini sol-gel method
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Studies on seed germination and response to fertilization of Amaranthus accessions collected in the Eastern Cape Province, South Africa
- Ramangoele, Mpaballeng Alinah
- Authors: Ramangoele, Mpaballeng Alinah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54112 , vital:46307
- Description: Studies were conducted at Döhne Agricultural Development Institute (D.A.D.I.), geographically located between latitude 32°31'34.077"S and longitude 27°27'37.473"E in Stutterheim, Eastern Cape Province from summer 2018 until autumn 2019.The objectives were to determine seed germination and seedling vigour of four local Amaranthus accessions and to evaluate the effect of organic and inorganic fertilization on the growth, yield and nutrient composition. In the germination studies, herein referred to as Experiment 1,laboratory assessments were laid out in a Complete Randomized Design (CRD) replicated four times to test seed germination, seedling emergence and seedling vigour of four Amaranthus accessions namely: A. Hypochondriacus, A. Retroflexus 1, A. Hybridus and A. Retroflexus 2. Data collection included germination percentage, radicle length, co-efficient of velocity of germination and seedling vigour. A.Retroflexus2 gave the highest germination percentage in summer (85%) and autumn (87.75%).Seed weight resulted in the highest germination percentage and was observed to have shown a high positive correlation of {R2=0.91} in summer and{R2=0.92} in autumn respectively. The highest seedling vigour (p<0.001) in summer was attained from A. Hypochondriacus and A. Retroflexus2.In the greenhouse in summer, the highest emergence percentage was observed from A. Hypochondriacus(93.00%), whilst in autumn it was A.Retroflexus2 (88.38%).A. Retroflexus1 was the least performer in both seasons. In summer, A. Hypochondriacus and A. Retroflexus2 resulted in very high seedling vigour. In autumn A. Hypochondriacus, A. Retroflexus2 and A. Hybridus resulted in high seedling vigour and A. Retroflexus1 in moderate seedling vigour. The relationship observed between seed weight and seedling vigour showed a negative (inverse)correlation in summer {R2=0.58} and autumn {R2=0.62}.In Experiment 2, seedlings of A. Hypochondriacus and A. Retroflexus 2were transplanted in 5litrebasal perforated plastic pots which were filled with soil. The experimental layout was a CRD replicated four times. The treatments were: control (no amendment), goat manure, cattle manure and NPK fertilizer. Growth performance data were collected for plant height, the number of leaves and stem girth. In summer, when goat manure was applied both accessions resulted in the tallest plants (78.80cm) yet A. Retroflexus 2 and vA. Hypochondriacus gave the greatest stem girthand highest number of leaves respectively. In autumn, the tallest plants and highest number of leaves were observed from A. Retroflexus 2fertilized with NPK and the greatest stem girth was observed from A. Hypochondriacus fertilized with goat manure. The interaction of fertilization and accessions resulted in A. Retroflexus 2 fertilized with goat manure generating the greatest fresh shoot biomass (137.27g plant-1) and the least from the control. Both accessions fertilized with goat manure attained the greatest dry leaf biomass. Insummer, A.Retroflexus2 outperformed A. Hypochondriacus in calcium content despite the treatments. Unfertilized A. Retroflexus2 produced leaves with high potassium. Both unfertilized accessions showed the highest magnesium content. All A. Retroflexus2 treatments outperformed A. Hypochondriacus treatments on iron content except the control. The summer season was the best in terms of growth and yield of the tested accessions. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Ramangoele, Mpaballeng Alinah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54112 , vital:46307
- Description: Studies were conducted at Döhne Agricultural Development Institute (D.A.D.I.), geographically located between latitude 32°31'34.077"S and longitude 27°27'37.473"E in Stutterheim, Eastern Cape Province from summer 2018 until autumn 2019.The objectives were to determine seed germination and seedling vigour of four local Amaranthus accessions and to evaluate the effect of organic and inorganic fertilization on the growth, yield and nutrient composition. In the germination studies, herein referred to as Experiment 1,laboratory assessments were laid out in a Complete Randomized Design (CRD) replicated four times to test seed germination, seedling emergence and seedling vigour of four Amaranthus accessions namely: A. Hypochondriacus, A. Retroflexus 1, A. Hybridus and A. Retroflexus 2. Data collection included germination percentage, radicle length, co-efficient of velocity of germination and seedling vigour. A.Retroflexus2 gave the highest germination percentage in summer (85%) and autumn (87.75%).Seed weight resulted in the highest germination percentage and was observed to have shown a high positive correlation of {R2=0.91} in summer and{R2=0.92} in autumn respectively. The highest seedling vigour (p<0.001) in summer was attained from A. Hypochondriacus and A. Retroflexus2.In the greenhouse in summer, the highest emergence percentage was observed from A. Hypochondriacus(93.00%), whilst in autumn it was A.Retroflexus2 (88.38%).A. Retroflexus1 was the least performer in both seasons. In summer, A. Hypochondriacus and A. Retroflexus2 resulted in very high seedling vigour. In autumn A. Hypochondriacus, A. Retroflexus2 and A. Hybridus resulted in high seedling vigour and A. Retroflexus1 in moderate seedling vigour. The relationship observed between seed weight and seedling vigour showed a negative (inverse)correlation in summer {R2=0.58} and autumn {R2=0.62}.In Experiment 2, seedlings of A. Hypochondriacus and A. Retroflexus 2were transplanted in 5litrebasal perforated plastic pots which were filled with soil. The experimental layout was a CRD replicated four times. The treatments were: control (no amendment), goat manure, cattle manure and NPK fertilizer. Growth performance data were collected for plant height, the number of leaves and stem girth. In summer, when goat manure was applied both accessions resulted in the tallest plants (78.80cm) yet A. Retroflexus 2 and vA. Hypochondriacus gave the greatest stem girthand highest number of leaves respectively. In autumn, the tallest plants and highest number of leaves were observed from A. Retroflexus 2fertilized with NPK and the greatest stem girth was observed from A. Hypochondriacus fertilized with goat manure. The interaction of fertilization and accessions resulted in A. Retroflexus 2 fertilized with goat manure generating the greatest fresh shoot biomass (137.27g plant-1) and the least from the control. Both accessions fertilized with goat manure attained the greatest dry leaf biomass. Insummer, A.Retroflexus2 outperformed A. Hypochondriacus in calcium content despite the treatments. Unfertilized A. Retroflexus2 produced leaves with high potassium. Both unfertilized accessions showed the highest magnesium content. All A. Retroflexus2 treatments outperformed A. Hypochondriacus treatments on iron content except the control. The summer season was the best in terms of growth and yield of the tested accessions. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
Spatial modelling of accessibility to tuberculosis treatment: the case of Ngaka Modiri Molema District
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04