Investigating the use of nudging to dissuade online banking fraud
- Mutyavariri, Takudzwa Stanley
- Authors: Mutyavariri, Takudzwa Stanley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419462 , vital:71646
- Description: Online banking is a service offered by most modern banks to provide their clients with a convenient means to access their bank accounts remotely. However, such convenience comes at a cost and has the potential to expose clients to online banking fraud. To mitigate such forms of fraud, banks make extensive use of traditional cybersecurity measures such as firewalls, intrusion detection systems, as well as personal identification numbers (PINs) and passwords. However, despite the use of such traditional cybersecurity measures, online banking fraud still occurs. In particular, traditional cybersecurity measures have difficulties detecting the unauthorised use of a customer’s online banking credentials. For this reason, this study’s main objective was to investigate the effectiveness of nudges when used to dissuade the unauthorised use of clients’ online banking credentials. The study also had two secondary objectives: firstly, to identify where the deployment of nudges would be most effective; and secondly, to identify the rationalisations an individual may use to justify committing online banking fraud. Although previous research has sought to understand the use of nudges in various online contexts, none have done so within the context of online banking. Using a recontextualised version of the COM-B (capability, opportunity, motivation – behaviour) model of behaviour change, nudges were deployed in three versions of a fictitious online banking website. Following this, 15 semi-structured interviews were conducted with online banking users from the United States of America to understand how a third party may behave and rationalise their choices when they have unauthorised access to a customer’s online banking credentials. The transcripts of these interviews were analysed using thematic analysis. The findings revealed that the most dissuasive nudges focused on encouraging individuals to empathise with the account holder. Nudges that increased the perception of an online banking website’s security were also particularly dissuasive. The findings also indicated that the most effective place to deploy these nudges was after a user had logged in. Several rationalisations that enabled individuals to commit online baking fraud were found. The three most common were crime of opportunity, down on their luck, and sunk cost fallacy and curiosity. Together, the findings provide evidence to suggest that, if used effectively, nudges could prove useful as a means of dissuading online banking fraud, and even more so when combined with traditional cybersecurity measures. , Thesis (MCom) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Mutyavariri, Takudzwa Stanley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419462 , vital:71646
- Description: Online banking is a service offered by most modern banks to provide their clients with a convenient means to access their bank accounts remotely. However, such convenience comes at a cost and has the potential to expose clients to online banking fraud. To mitigate such forms of fraud, banks make extensive use of traditional cybersecurity measures such as firewalls, intrusion detection systems, as well as personal identification numbers (PINs) and passwords. However, despite the use of such traditional cybersecurity measures, online banking fraud still occurs. In particular, traditional cybersecurity measures have difficulties detecting the unauthorised use of a customer’s online banking credentials. For this reason, this study’s main objective was to investigate the effectiveness of nudges when used to dissuade the unauthorised use of clients’ online banking credentials. The study also had two secondary objectives: firstly, to identify where the deployment of nudges would be most effective; and secondly, to identify the rationalisations an individual may use to justify committing online banking fraud. Although previous research has sought to understand the use of nudges in various online contexts, none have done so within the context of online banking. Using a recontextualised version of the COM-B (capability, opportunity, motivation – behaviour) model of behaviour change, nudges were deployed in three versions of a fictitious online banking website. Following this, 15 semi-structured interviews were conducted with online banking users from the United States of America to understand how a third party may behave and rationalise their choices when they have unauthorised access to a customer’s online banking credentials. The transcripts of these interviews were analysed using thematic analysis. The findings revealed that the most dissuasive nudges focused on encouraging individuals to empathise with the account holder. Nudges that increased the perception of an online banking website’s security were also particularly dissuasive. The findings also indicated that the most effective place to deploy these nudges was after a user had logged in. Several rationalisations that enabled individuals to commit online baking fraud were found. The three most common were crime of opportunity, down on their luck, and sunk cost fallacy and curiosity. Together, the findings provide evidence to suggest that, if used effectively, nudges could prove useful as a means of dissuading online banking fraud, and even more so when combined with traditional cybersecurity measures. , Thesis (MCom) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
Investigating thermoregulatory responses of rhabdomys pumilio at high wet-bulb temperatures
- Authors: Hartley, Oliver
- Date: 2023-04
- Subjects: Heat stress physiology , Small mammal thermoregulation -- South Africa , Climate change - Wet-bulb temperature
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60873 , vital:68916
- Description: As the Anthropocene continues to be characterised by ever rising temperature highs, increasingly sporadic and extreme climatic events, and their accompanying mass mortality events, climate scientists now warn that the continued climate destabilisation may for the first time in recorded history prevent terrestrial homeothermic endotherms from being able to thermoregulate. Having evolved to maintain body temperatures (Tbs) well above their ambient (Ta) conditions, these endotherms have evolved a suite of adaptations to a colder environment to allow for homeothermic thermoregulation to occur. However, by the same vein, having evolved in a colder climate to stay warm also has led to a reduced capacity to prevent heat stress when temperature conditions are elevated. In absence of behavioural counter measures, the only physiological means available to thermoregulation to prevent such heat stress is that of evaporative water loss (EWL). If still inefficient, the endotherm will risk becoming hyperthermic. Literature has established that excessive heat exposure or reduced evaporative cooling capacities strain or retard thermoregulatory processes. If an endotherm experiences severe heat exposure, the rate at which passive heating is experienced will increase. Should an endotherm be in a humid environment, evaporative cooling efficiency is reduced. As a result, these two abiotic factors are therefore known to contribute towards heat storage, and therefore thermal stress. However, should both factors occur in the same environment, the heat stress effects are compounded, creating an environment dangerous for thermoregulating endotherms. For this reason, authors have emphasised that future wet-bulb (Tw) conditions may pose a penultimate threat to thermoregulating endotherms. Being a measure of coldest temperature attainable as a result of evaporative cooling, Tw has been proposed to represent a lower temperature thermal limit to endothermic thermoregulation. Once reaching a 2°C differential below an endotherms Tb (Tb – Tw = 2˚C), Tw is believed to impede the evaporative cooling process and, consequentially, commit endotherms to becoming hyperthermic. Considering that most mammals defend constant Tbs within the range of predicted Tw maxima increases that future Tw conditions may pose a significant threat to mammalian thermoregulation. However, to date, despite being well supported in the literature, ii empirical investigations into how extreme Tw conditions will affect endothermic thermoregulation are scant. Therefore, understanding of the proposed inhibitory nature of extreme Tw conditions is lacking. Considering that such conditions are to have a profound effect of endothermic survival, this dearth in understanding could prove fatal. As such, this thesis sought to provide evidence on how extreme Tw conditions may affect thermoregulatory processes in homeothermic endotherms. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Hartley, Oliver
- Date: 2023-04
- Subjects: Heat stress physiology , Small mammal thermoregulation -- South Africa , Climate change - Wet-bulb temperature
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60873 , vital:68916
- Description: As the Anthropocene continues to be characterised by ever rising temperature highs, increasingly sporadic and extreme climatic events, and their accompanying mass mortality events, climate scientists now warn that the continued climate destabilisation may for the first time in recorded history prevent terrestrial homeothermic endotherms from being able to thermoregulate. Having evolved to maintain body temperatures (Tbs) well above their ambient (Ta) conditions, these endotherms have evolved a suite of adaptations to a colder environment to allow for homeothermic thermoregulation to occur. However, by the same vein, having evolved in a colder climate to stay warm also has led to a reduced capacity to prevent heat stress when temperature conditions are elevated. In absence of behavioural counter measures, the only physiological means available to thermoregulation to prevent such heat stress is that of evaporative water loss (EWL). If still inefficient, the endotherm will risk becoming hyperthermic. Literature has established that excessive heat exposure or reduced evaporative cooling capacities strain or retard thermoregulatory processes. If an endotherm experiences severe heat exposure, the rate at which passive heating is experienced will increase. Should an endotherm be in a humid environment, evaporative cooling efficiency is reduced. As a result, these two abiotic factors are therefore known to contribute towards heat storage, and therefore thermal stress. However, should both factors occur in the same environment, the heat stress effects are compounded, creating an environment dangerous for thermoregulating endotherms. For this reason, authors have emphasised that future wet-bulb (Tw) conditions may pose a penultimate threat to thermoregulating endotherms. Being a measure of coldest temperature attainable as a result of evaporative cooling, Tw has been proposed to represent a lower temperature thermal limit to endothermic thermoregulation. Once reaching a 2°C differential below an endotherms Tb (Tb – Tw = 2˚C), Tw is believed to impede the evaporative cooling process and, consequentially, commit endotherms to becoming hyperthermic. Considering that most mammals defend constant Tbs within the range of predicted Tw maxima increases that future Tw conditions may pose a significant threat to mammalian thermoregulation. However, to date, despite being well supported in the literature, ii empirical investigations into how extreme Tw conditions will affect endothermic thermoregulation are scant. Therefore, understanding of the proposed inhibitory nature of extreme Tw conditions is lacking. Considering that such conditions are to have a profound effect of endothermic survival, this dearth in understanding could prove fatal. As such, this thesis sought to provide evidence on how extreme Tw conditions may affect thermoregulatory processes in homeothermic endotherms. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Investigation into methods of recovering campylobacter spp. from river water samples
- Authors: Ngoni, Nandipha
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424177 , vital:72130
- Description: Campylobacter species are slender, gram-negative, rod-shaped, spiral- or curved-shaped with single or pairs of flagella. They are the leading cause of diarrheal disease globally, consumption of and contact with water contaminated by faeces is a major risk factor for transmission of these organisms to humans. Rivers used for recreation and domestic and agricultural activities represent all the risk factors for Campylobacter spp. pollution and human exposure. Campylobacter spp. However, effective methods to recover Campylobacter spp. from river water samples are lacking, indicating the need for the development of more efficient methods of detection and isolation of these organisms from environmental water samples. Campylobacter detection in a water sample is critical to ascertain potential risks to humans. The aim of this study was to determine a suitable method for the detection of Campylobacter spp. from river water samples and the objectives were to (i) to evaluate the performance of different methods used for the recovery of Campylobacter spp. from environmental water samples based on Campylobacter colony count and PCR identification results, (ii) isolate and enumerate Campylobacter cells from river water samples, and (iii) identify Campylobacter spp. in river water samples. The Bloukrans River was chosen for this study because it is suspected to be contaminated by faecal inputs from nearby informal settlements without adequate sanitation, as well as untreated/insufficiently treated effluents from nearby wastewater treatment plants. First, the physicochemical quality of the river water and the presence of faecal contamination were assessed to confirm suitability for Campylobacter spp. survival and presence. Then different approaches to sample, concentrate and recover Campylobacter spp. from river water samples were assessed. The different methods assessed were (i) direct enrichment of water samples without prior concentration, (ii) prior concentration of water samples by centrifugation followed by membrane filtration of supernatant, and after that, pooling the residue and pellet together for enrichment, (iii) sampling by the Moore Swab technique. For all three methods, enrichment in Bolton broth supplemented with Bolton antibiotics was conducted. This was followed by plating on modified cefoperazone charcoal deoxycholate agar (mCCDA) and incubation under a microaerophilic atmosphere at 42°C for 48 h. Colony morphology, Gram staining and polymerase chain reaction (PCR) were used to identify and characterize the microorganisms. The growth of blue colonies on the mFc agar surface confirmed presence and faecal pollution of the Bloukrans River. The physicochemical properties, based on the range of pH measured at different sites of the river (between acidic 3.45 to 6.42 and alkaline 7.2 to 8.74) indicate that Campylobacter spp. can thrive in the river. Based on the results from enumeration and sequencing of colonies recovered by each method, it was discovered that the most suitable method to recover Campylobacter spp. from river water samples is by prior centrifugation (14,000 × g for 30 minutes) followed by membrane filtration of the supernatant, and subsequent pooling of the residue and pellet. The pooled residue and pellet might have increased Campylobacter spp. concentrations aiding more growth during the enrichment of Campylobacter spp. from the river water samples. Results from enumerating Campylobacter spp. cells from river water samples indicate that Campylobacter spp. are present in Bloukrans River. The sequence obtained from the PCR product indicates that the species found were Campylobacter jejuni (96% homology as evaluated by BLAST). This study provided a procedure effective for obtaining a satisfactory quantitative recovery of Campylobacter spp. from environmental waters, a critical need for quantitative microbial risk assessment studies. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Ngoni, Nandipha
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424177 , vital:72130
- Description: Campylobacter species are slender, gram-negative, rod-shaped, spiral- or curved-shaped with single or pairs of flagella. They are the leading cause of diarrheal disease globally, consumption of and contact with water contaminated by faeces is a major risk factor for transmission of these organisms to humans. Rivers used for recreation and domestic and agricultural activities represent all the risk factors for Campylobacter spp. pollution and human exposure. Campylobacter spp. However, effective methods to recover Campylobacter spp. from river water samples are lacking, indicating the need for the development of more efficient methods of detection and isolation of these organisms from environmental water samples. Campylobacter detection in a water sample is critical to ascertain potential risks to humans. The aim of this study was to determine a suitable method for the detection of Campylobacter spp. from river water samples and the objectives were to (i) to evaluate the performance of different methods used for the recovery of Campylobacter spp. from environmental water samples based on Campylobacter colony count and PCR identification results, (ii) isolate and enumerate Campylobacter cells from river water samples, and (iii) identify Campylobacter spp. in river water samples. The Bloukrans River was chosen for this study because it is suspected to be contaminated by faecal inputs from nearby informal settlements without adequate sanitation, as well as untreated/insufficiently treated effluents from nearby wastewater treatment plants. First, the physicochemical quality of the river water and the presence of faecal contamination were assessed to confirm suitability for Campylobacter spp. survival and presence. Then different approaches to sample, concentrate and recover Campylobacter spp. from river water samples were assessed. The different methods assessed were (i) direct enrichment of water samples without prior concentration, (ii) prior concentration of water samples by centrifugation followed by membrane filtration of supernatant, and after that, pooling the residue and pellet together for enrichment, (iii) sampling by the Moore Swab technique. For all three methods, enrichment in Bolton broth supplemented with Bolton antibiotics was conducted. This was followed by plating on modified cefoperazone charcoal deoxycholate agar (mCCDA) and incubation under a microaerophilic atmosphere at 42°C for 48 h. Colony morphology, Gram staining and polymerase chain reaction (PCR) were used to identify and characterize the microorganisms. The growth of blue colonies on the mFc agar surface confirmed presence and faecal pollution of the Bloukrans River. The physicochemical properties, based on the range of pH measured at different sites of the river (between acidic 3.45 to 6.42 and alkaline 7.2 to 8.74) indicate that Campylobacter spp. can thrive in the river. Based on the results from enumeration and sequencing of colonies recovered by each method, it was discovered that the most suitable method to recover Campylobacter spp. from river water samples is by prior centrifugation (14,000 × g for 30 minutes) followed by membrane filtration of the supernatant, and subsequent pooling of the residue and pellet. The pooled residue and pellet might have increased Campylobacter spp. concentrations aiding more growth during the enrichment of Campylobacter spp. from the river water samples. Results from enumerating Campylobacter spp. cells from river water samples indicate that Campylobacter spp. are present in Bloukrans River. The sequence obtained from the PCR product indicates that the species found were Campylobacter jejuni (96% homology as evaluated by BLAST). This study provided a procedure effective for obtaining a satisfactory quantitative recovery of Campylobacter spp. from environmental waters, a critical need for quantitative microbial risk assessment studies. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
- Full Text:
- Date Issued: 2023-10-13
Investigation into response of wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa
- Authors: Mzileni L S
- Date: 2023
- Subjects: Bonanza farms , Wheat , Drought - tolerant plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27732 , vital:69397
- Description: Wheat is generally one of the dominant crops globally, being mainly used for human food and livestock feed. Due to climate change, drought makes it challenging to produce enough wheat mostly under dryland production regions in South Africa. Drought stress has severely reduced wheat yield by up to 70 percent, and adversely compromised wheat grain quality. The adoption of drought-tolerant cultivars offers a sustainable and low-cost solution for increasing wheat yields and minimise importing the crop to meet national requirements. The main objective of this study was to investigate the response of different wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa. Forty diverse wheat genotypes were evaluated in this study. The specific objectives were: (i) to evaluate the response of wheat genotypes under optimum and drought-stressed field conditions; (ii) to determine the effect of terminal drought stress on wheat grain quality composition; and (iii) to identify appropriate drought tolerance indices that can be used as selection tools under field conditions. This study was conducted in the field using a 5x8 alpha lattice design, replicated twice under two water regimes (drought and optimum) over two consecutive winter seasons of 2020 and 2021 at two different sites namely University of Fort Hare Research Farm in Alice, and Zanyokwe irrigation scheme in Keiskamahoek. Drought stress was imposed from 50% flowering up to physiological maturity. Data on agro-physiological traits such as duration to heading (DTH); flowering (DTF); maturity (DTM); plant height (HT); spike length (SL); number of spikelets per spike (SPS); kernels per spike (KPS); and grain yield (GY (kg/ha)) was subjected to the analysis of variance using Genstat 18th edition. As the study took place over two sites, a combined ANOVA table revealed significant differences (p0.001) among genotypes, and all interactions such as genotype by water regime (GWR); genotype by seasons (GS) for all studied traits. Notably, the extent and severity of drought differed between geographical regions and between seasons. This necessitated the adoption of the additive main effect and multiplicative interaction analysis (AMMI) for the identification of stable genotypes under two different water regimes over two sites. Regarding grain yield, superior and/or stable genotypes included G5 (4334 kg/ha under optimum, and 2871kg/ha under drought), and G22 (4418 kg/ha under optimum, and 2624kg/ha under drought) at the UFH site. G21 (3194 kg/ha under optimum, and 2938 kg/ha under drought), G33 (2552kg/ha under optimum, and 3810 kg/ha under drought), and G35 (2688 kg/ha under optimum, and 3309 kg/ha under drought) at the ZAN site. Stable genotypes across sites included G21 and G33. There were generally weak correlations between agro-physiological traits and grain yield. From the experiment, grain quality traits such as fixed protein (PF); wet gluten (WG); hectolitre mass (HLM); and thousand kernel weight (TKW) were also examined. A combined ANOVA revealed significant differences (p0.001) among the interaction of genotypes by environments (GE) for all traits except PF. This implies that the performance of wheat genotypes across sites was also different, and therefore, necessitated separate analysis of variance for each site. Significant differences (p0.001) among genotypes (G), water regimes (WR), and the interaction of genotypes by water regime (GWR) were observed for all studied quality traits except PF in both sites. GWR showed no significant differences for TKW in the ZAN site. The stability in the performance of genotypes across water regimes was further determined. G38 was stable for wet gluten; G31 and G26 were stable for PF; G36 was stable for HLM; and G11, G15, and G29 were stable for TKW at the UFH site. G6 was stable for both WG and PF; G13 and G15 were stable for HLM; and G35, G21, and G40 were stable for TKW at the ZAN site. These results suggest that the quality of wheat grains was affected under drought stress conditions except PF. Average grain yield data under both stressed (Ys) and optimum (Yp) conditions was used to compute a number of different drought tolerance indices. These include mean productivity (MP); geometric mean productivity (GMP); harmonic mean (HM); Tolerance index (TOL), stress susceptible index (SSI), sensitive drought index (SDI), and stress tolerance index (STI). The aim was to identify appropriate drought tolerance indices that can be used as selection tools under drought stress. MP, GMP, and HM were the more appropriate indices as they had a strong and positive correlation with grain yield under both drought and optimum conditions. However, genotypes G5, G22, G8, and G21 were more tolerant and stable as they showed high mean values. Based on the results, G19, G16, G2, and G20 were more sensitive to drought as they showed low values of MP, GMP, and HM. Overall, genotype: G5, G21, G22, and G33 are recommended for production under drought and optimum conditions, as they showed stable performance across water regimes. Principal component analysis also revealed that MP, GMP, and HM were the only indices that had positive loadings into the first principal component. , Thesis (MSc) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023
- Authors: Mzileni L S
- Date: 2023
- Subjects: Bonanza farms , Wheat , Drought - tolerant plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27732 , vital:69397
- Description: Wheat is generally one of the dominant crops globally, being mainly used for human food and livestock feed. Due to climate change, drought makes it challenging to produce enough wheat mostly under dryland production regions in South Africa. Drought stress has severely reduced wheat yield by up to 70 percent, and adversely compromised wheat grain quality. The adoption of drought-tolerant cultivars offers a sustainable and low-cost solution for increasing wheat yields and minimise importing the crop to meet national requirements. The main objective of this study was to investigate the response of different wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa. Forty diverse wheat genotypes were evaluated in this study. The specific objectives were: (i) to evaluate the response of wheat genotypes under optimum and drought-stressed field conditions; (ii) to determine the effect of terminal drought stress on wheat grain quality composition; and (iii) to identify appropriate drought tolerance indices that can be used as selection tools under field conditions. This study was conducted in the field using a 5x8 alpha lattice design, replicated twice under two water regimes (drought and optimum) over two consecutive winter seasons of 2020 and 2021 at two different sites namely University of Fort Hare Research Farm in Alice, and Zanyokwe irrigation scheme in Keiskamahoek. Drought stress was imposed from 50% flowering up to physiological maturity. Data on agro-physiological traits such as duration to heading (DTH); flowering (DTF); maturity (DTM); plant height (HT); spike length (SL); number of spikelets per spike (SPS); kernels per spike (KPS); and grain yield (GY (kg/ha)) was subjected to the analysis of variance using Genstat 18th edition. As the study took place over two sites, a combined ANOVA table revealed significant differences (p0.001) among genotypes, and all interactions such as genotype by water regime (GWR); genotype by seasons (GS) for all studied traits. Notably, the extent and severity of drought differed between geographical regions and between seasons. This necessitated the adoption of the additive main effect and multiplicative interaction analysis (AMMI) for the identification of stable genotypes under two different water regimes over two sites. Regarding grain yield, superior and/or stable genotypes included G5 (4334 kg/ha under optimum, and 2871kg/ha under drought), and G22 (4418 kg/ha under optimum, and 2624kg/ha under drought) at the UFH site. G21 (3194 kg/ha under optimum, and 2938 kg/ha under drought), G33 (2552kg/ha under optimum, and 3810 kg/ha under drought), and G35 (2688 kg/ha under optimum, and 3309 kg/ha under drought) at the ZAN site. Stable genotypes across sites included G21 and G33. There were generally weak correlations between agro-physiological traits and grain yield. From the experiment, grain quality traits such as fixed protein (PF); wet gluten (WG); hectolitre mass (HLM); and thousand kernel weight (TKW) were also examined. A combined ANOVA revealed significant differences (p0.001) among the interaction of genotypes by environments (GE) for all traits except PF. This implies that the performance of wheat genotypes across sites was also different, and therefore, necessitated separate analysis of variance for each site. Significant differences (p0.001) among genotypes (G), water regimes (WR), and the interaction of genotypes by water regime (GWR) were observed for all studied quality traits except PF in both sites. GWR showed no significant differences for TKW in the ZAN site. The stability in the performance of genotypes across water regimes was further determined. G38 was stable for wet gluten; G31 and G26 were stable for PF; G36 was stable for HLM; and G11, G15, and G29 were stable for TKW at the UFH site. G6 was stable for both WG and PF; G13 and G15 were stable for HLM; and G35, G21, and G40 were stable for TKW at the ZAN site. These results suggest that the quality of wheat grains was affected under drought stress conditions except PF. Average grain yield data under both stressed (Ys) and optimum (Yp) conditions was used to compute a number of different drought tolerance indices. These include mean productivity (MP); geometric mean productivity (GMP); harmonic mean (HM); Tolerance index (TOL), stress susceptible index (SSI), sensitive drought index (SDI), and stress tolerance index (STI). The aim was to identify appropriate drought tolerance indices that can be used as selection tools under drought stress. MP, GMP, and HM were the more appropriate indices as they had a strong and positive correlation with grain yield under both drought and optimum conditions. However, genotypes G5, G22, G8, and G21 were more tolerant and stable as they showed high mean values. Based on the results, G19, G16, G2, and G20 were more sensitive to drought as they showed low values of MP, GMP, and HM. Overall, genotype: G5, G21, G22, and G33 are recommended for production under drought and optimum conditions, as they showed stable performance across water regimes. Principal component analysis also revealed that MP, GMP, and HM were the only indices that had positive loadings into the first principal component. , Thesis (MSc) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023
Investigation of brewery waste grains and microbial fuel cells as value-additive technologies improving solvent production yields in Clostridium acetobutylicum (ATCC 824) fermentation
- Authors: Du Toit, Ryan Guillaume
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424643 , vital:72171
- Description: The production of the solvent compounds acetone, ethanol and butanol through fermentation of organic feedstocks using Clostridia species could be a promising route for biofuel production. However, the cost of raw materials, low yields and the complexity of anaerobic fermentation continue to hinder this means of generating these compounds. The research presented in this Thesis investigated low-cost interventions that could decrease the costs of production and to direct the synthesis of fuel compounds using microbial fuel cells. Low-cost anaerobic chambers were designed and constructed for the propagation and manipulation of Clostridium acetobutylicum, selected as a low-risk microbial catalyst. Fermentation was monitored using in situ pH measurements and a combination of turbidity measurements, nutrient assays (especially total carbohydrates) and HPLC-RI detection as a means of monitoring the consumption of nutrients (glucose), production of precursor compounds (butyric acid) and the formation of solvent molecules (acetone/ethanol and butanol) during fermentation by this organism. Brewer’s spent grains were tested as a sustainable and low-cost feedstock for solvent production, comparing the effects of sterilising before fermentation, or allowing resident microflora to remain during Clostridium-catalysed solvent production. Sterilised spent grains significantly improved the production of solvent molecules (e.g. 12.97 ± 0.38 g/L of butanol yielded, compared to 0.40 ± 0.33 g/L for defined media sampled during the solventogenic phase); compared to these, the use of non-sterilised brewer’s grain decreased both the reproducibility and yields of fermentation (8.66 ± 1.6 g/L of butanol). Microbial fuel cells were studied as a possible means of altering electron transfer to/from electrode-attached Clostridia to control the metabolic shift in bacteria from acidogenesis to solventogenesis. The base line MFC (11.00 ± 4.69 g/L) fermentation experiment did produce higher acetone/ethanol than the baseline batch experiment MB (5.47 ± 4.48 g/L), indicating an improvement to solvent production in C. acetobutylicum (ATCC 824) in a MFC fermentation. In this study, MFC-1 demonstrated remarkable superiority over MB in terms of butyric acid production, yielding significantly higher concentrations while also improving acetone and ethanol production. However, the enhanced butyric acid production did not correspond to significantly increased butanol yields when compared to batch fermentation of chemically defined media. These findings highlight the potential of MFC-1 as an efficient approach for enhancing the fermentative production of valuable compounds, with a particular focus on butyric acid and acetone/ethanol. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Du Toit, Ryan Guillaume
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424643 , vital:72171
- Description: The production of the solvent compounds acetone, ethanol and butanol through fermentation of organic feedstocks using Clostridia species could be a promising route for biofuel production. However, the cost of raw materials, low yields and the complexity of anaerobic fermentation continue to hinder this means of generating these compounds. The research presented in this Thesis investigated low-cost interventions that could decrease the costs of production and to direct the synthesis of fuel compounds using microbial fuel cells. Low-cost anaerobic chambers were designed and constructed for the propagation and manipulation of Clostridium acetobutylicum, selected as a low-risk microbial catalyst. Fermentation was monitored using in situ pH measurements and a combination of turbidity measurements, nutrient assays (especially total carbohydrates) and HPLC-RI detection as a means of monitoring the consumption of nutrients (glucose), production of precursor compounds (butyric acid) and the formation of solvent molecules (acetone/ethanol and butanol) during fermentation by this organism. Brewer’s spent grains were tested as a sustainable and low-cost feedstock for solvent production, comparing the effects of sterilising before fermentation, or allowing resident microflora to remain during Clostridium-catalysed solvent production. Sterilised spent grains significantly improved the production of solvent molecules (e.g. 12.97 ± 0.38 g/L of butanol yielded, compared to 0.40 ± 0.33 g/L for defined media sampled during the solventogenic phase); compared to these, the use of non-sterilised brewer’s grain decreased both the reproducibility and yields of fermentation (8.66 ± 1.6 g/L of butanol). Microbial fuel cells were studied as a possible means of altering electron transfer to/from electrode-attached Clostridia to control the metabolic shift in bacteria from acidogenesis to solventogenesis. The base line MFC (11.00 ± 4.69 g/L) fermentation experiment did produce higher acetone/ethanol than the baseline batch experiment MB (5.47 ± 4.48 g/L), indicating an improvement to solvent production in C. acetobutylicum (ATCC 824) in a MFC fermentation. In this study, MFC-1 demonstrated remarkable superiority over MB in terms of butyric acid production, yielding significantly higher concentrations while also improving acetone and ethanol production. However, the enhanced butyric acid production did not correspond to significantly increased butanol yields when compared to batch fermentation of chemically defined media. These findings highlight the potential of MFC-1 as an efficient approach for enhancing the fermentative production of valuable compounds, with a particular focus on butyric acid and acetone/ethanol. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-10-13
Investigation of electrocatalytic behaviour of low symmetry cobalt phthalocyanines when clicked to azide grafted carbon electrodes
- Mpeta, Lakethe S, Sen, Pinar, Nyokong, Tebello
- Authors: Mpeta, Lakethe S , Sen, Pinar , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186304 , vital:44483 , xlink:href="https://doi.org/10.1016/j.jelechem.2020.113896"
- Description: This work describes the electrochemical properties of low symmetry cobalt phthalocyanines namely, tris-[(4-tert-butylphenoxy)-4-(pent-4-yn-1-yloxy) phthalocyaniato] cobalt (II) (3) and tris-[(4-tert-butylphenoxy)-4-(4-ethybylbenzyl-oxy) phthalocyaniato] cobalt (II) (5). The complexes were characterized by a number of techniques including UV–Vis, mass, and infrared spectra, as well as elemental analysis. The glassy carbon electrodes were first azide functionalized then clicked to low symmetry phthalocyanines. The click reaction was confirmed using X-ray photoelectron spectra. The constructed electrodes showed excellent electrocatalytic activity towards hydrazine oxidation. Oxidation peaks with low potentials of 0.21 V and 0.26 V, for complexes 3 and 5, respectively were obtained. Complex-5 gave a better detection limit of 0.94 μM and electrocatalytic rate constant of 5.6 × 106 M−1 s−1.
- Full Text:
- Date Issued: 2020
- Authors: Mpeta, Lakethe S , Sen, Pinar , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186304 , vital:44483 , xlink:href="https://doi.org/10.1016/j.jelechem.2020.113896"
- Description: This work describes the electrochemical properties of low symmetry cobalt phthalocyanines namely, tris-[(4-tert-butylphenoxy)-4-(pent-4-yn-1-yloxy) phthalocyaniato] cobalt (II) (3) and tris-[(4-tert-butylphenoxy)-4-(4-ethybylbenzyl-oxy) phthalocyaniato] cobalt (II) (5). The complexes were characterized by a number of techniques including UV–Vis, mass, and infrared spectra, as well as elemental analysis. The glassy carbon electrodes were first azide functionalized then clicked to low symmetry phthalocyanines. The click reaction was confirmed using X-ray photoelectron spectra. The constructed electrodes showed excellent electrocatalytic activity towards hydrazine oxidation. Oxidation peaks with low potentials of 0.21 V and 0.26 V, for complexes 3 and 5, respectively were obtained. Complex-5 gave a better detection limit of 0.94 μM and electrocatalytic rate constant of 5.6 × 106 M−1 s−1.
- Full Text:
- Date Issued: 2020
Investigation of homogeneous photosensitized oxidation activities of palladium and platinum octasubstituted phthalocyanines
- Ogunbayo, Taofeek B, Antunes, Edith M, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
Investigation of institutions for the implementation of the Dutywa Agripark Project in Mbashe Local Municipality in Eastern Cape Province, South Africa
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Investigation of microbial fuel cell technologies for flexible, small-scale domestic and educational use
- Authors: Mpofu, Trisha Lerato
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192539 , vital:45235
- Description: Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mpofu, Trisha Lerato
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192539 , vital:45235
- Description: Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
Investigation of novel substituted zinc and aluminium phthalocyanines for photodynamic therapy of epithelial breast cancer
- Mohammed, Imadalulla, Oluwole, David O, Nemakal, Majunatha, Sannegowda, Lokesh K, Nyokong, Tebello
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
- Date Issued: 2019
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
- Date Issued: 2019
Investigation of pharmaceutical residues and polybrominated diphenyl ethers in selected river estuaries and canal in Eastern Cape Province, South Africa
- Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Authors: Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Date: 2021-09
- Subjects: Marine pharmacology
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21545 , vital:48878
- Description: The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Date: 2021-09
- Subjects: Marine pharmacology
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21545 , vital:48878
- Description: The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles
- Dube, Edith, Nwaji, Njemuwa, Oluwole, David O, Mack, John, Nyokong, Tebello
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
Investigation of risky sexual behaviour amongst HIV/AIDS positive individuals on antiretroviral treatment in Buffalo City Metropolitan Municipality Eastern Cape Province, South Africa
- Authors: Pere, Mzukisi Ernest
- Date: 2022-07
- Subjects: Sexual behaviour -- South Africa -- Eastern Cape , Youth Sexual behaviour
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/23578 , vital:58190
- Description: Background: Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) is one of the major public health concerns. Antiretroviral treatments (ART) is available immediately for HIV-positive individuals but sexually transmitted infections are on the rise. The majority of HIV positive patients on ART are engaging in unsafe sexual practices. Purpose: The aim of this study was to investigate risky sexual behaviour of people on antiretroviral treatment regarding prevention. The study was conducted on adult clients in the Buffalo City Metropolitan Municipality. Methods: A quantitative and descriptive cross-sectional design was conducted whereby 304 patients who visited Nontyatyambo Health Centre were randomly selected. Data was entered and analyzed using Statistical Package for the Social Sciences (SPSS) 24. Simple descriptive statistics such as numbers, percentages and tables were used to characterise variables. A chi-square test was used to explore associations between dependent and independent variables. Test significance, confidence intervals and p-values of all the causes and contributory factors were set at 0.05. Results: Thirty two percent reported having sex with multiple sexual partners while 19percent reported never using a condom. Forty eight percent reported having had sexually transmitted infections since starting on ART. The median age (36 years (IQR: 31, 45) vs. 35 years (IQR: 26, 40)) of those who reported STIs was higher than the median age of those who did not report STI (p=0.012). Males (57percent, p=0.049), those who were employed (55percent, p=0.048), and those who were cohabitating (68percent, 0.030) were more likely to report STI. Similarly, those who had unprotected sex with a casual partner (62percent, p<0.001), and those who did not use a condom because a partner did not like it (71percent, p=0.001) were more likely to report STIs. A significant number of 32percent of the participants reported engaging in risky sexual practices while 48percent had reported an STI. Recommendations include educational outreach programmes and capacitation of health care workers with appropriate skills and tools. , Thesis (MPH) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-07
- Authors: Pere, Mzukisi Ernest
- Date: 2022-07
- Subjects: Sexual behaviour -- South Africa -- Eastern Cape , Youth Sexual behaviour
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/23578 , vital:58190
- Description: Background: Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) is one of the major public health concerns. Antiretroviral treatments (ART) is available immediately for HIV-positive individuals but sexually transmitted infections are on the rise. The majority of HIV positive patients on ART are engaging in unsafe sexual practices. Purpose: The aim of this study was to investigate risky sexual behaviour of people on antiretroviral treatment regarding prevention. The study was conducted on adult clients in the Buffalo City Metropolitan Municipality. Methods: A quantitative and descriptive cross-sectional design was conducted whereby 304 patients who visited Nontyatyambo Health Centre were randomly selected. Data was entered and analyzed using Statistical Package for the Social Sciences (SPSS) 24. Simple descriptive statistics such as numbers, percentages and tables were used to characterise variables. A chi-square test was used to explore associations between dependent and independent variables. Test significance, confidence intervals and p-values of all the causes and contributory factors were set at 0.05. Results: Thirty two percent reported having sex with multiple sexual partners while 19percent reported never using a condom. Forty eight percent reported having had sexually transmitted infections since starting on ART. The median age (36 years (IQR: 31, 45) vs. 35 years (IQR: 26, 40)) of those who reported STIs was higher than the median age of those who did not report STI (p=0.012). Males (57percent, p=0.049), those who were employed (55percent, p=0.048), and those who were cohabitating (68percent, 0.030) were more likely to report STI. Similarly, those who had unprotected sex with a casual partner (62percent, p<0.001), and those who did not use a condom because a partner did not like it (71percent, p=0.001) were more likely to report STIs. A significant number of 32percent of the participants reported engaging in risky sexual practices while 48percent had reported an STI. Recommendations include educational outreach programmes and capacitation of health care workers with appropriate skills and tools. , Thesis (MPH) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-07
Investigation of risky sexual behaviour amongst HIV/AIDS positive individuals on antiretroviral treatment in Buffalo City Metropolitan Municipality Eastern Cape Province, South Africa
- Authors: Pere, Mzukisi Ernest
- Date: 2022-07
- Subjects: HIV-positive persons , Sexually transmitted diseases , AIDS (Disease) -- Prevention
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27198 , vital:66395
- Description: Background: Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) is one of the major public health concerns. Antiretroviral treatments (ART) is available immediately for HIV-positive individuals but sexually transmitted infections are on the rise. The majority of HIV positive patients on ART are engaging in unsafe sexual practices. Purpose: The aim of this study was to investigate risky sexual behaviour of people on antiretroviral treatment regarding prevention. The study was conducted on adult clients in the Buffalo City Metropolitan Municipality. Methods: A quantitative and descriptive cross-sectional design was conducted whereby 304 patients who visited Nontyatyambo Health Centre were randomly selected. Data was entered and analyzed using Statistical Package for the Social Sciences (SPSS) 24. Simple descriptive statistics such as numbers, percentages and tables were used to characterise variables. A chi-square test was used to explore associations between dependent and independent variables. Test significance, confidence intervals and p-values of all the causes and contributory factors were set at 0.05. Results: Thirty two percent reported having sex with multiple sexual partners while 19percent reported never using a condom. Forty eight percent reported having had sexually transmitted infections since starting on ART. The median age (36 years (IQR: 31, 45) vs. 35 years (IQR: 26, 40)) of those who reported STIs was higher than the median age of those who did not report STI (p=0.012). Males (57percent, p=0.049), those who were employed (55percent, p=0.048), and those who were cohabitating (68percent, 0.030) were more likely to report STI. Similarly, those who had unprotected sex with a casual partner (62percent, p<0.001), and those who did not use a condom because a partner did not like it (71percent, p=0.001) were more likely to report STIs. A significant number of 32percent of the participants reported engaging in risky sexual practices while 48percent had reported an STI. Recommendations include educational outreach programmes and capacitation of health care workers with appropriate skills and tools. , Thesis (MPH) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-07
- Authors: Pere, Mzukisi Ernest
- Date: 2022-07
- Subjects: HIV-positive persons , Sexually transmitted diseases , AIDS (Disease) -- Prevention
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27198 , vital:66395
- Description: Background: Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) is one of the major public health concerns. Antiretroviral treatments (ART) is available immediately for HIV-positive individuals but sexually transmitted infections are on the rise. The majority of HIV positive patients on ART are engaging in unsafe sexual practices. Purpose: The aim of this study was to investigate risky sexual behaviour of people on antiretroviral treatment regarding prevention. The study was conducted on adult clients in the Buffalo City Metropolitan Municipality. Methods: A quantitative and descriptive cross-sectional design was conducted whereby 304 patients who visited Nontyatyambo Health Centre were randomly selected. Data was entered and analyzed using Statistical Package for the Social Sciences (SPSS) 24. Simple descriptive statistics such as numbers, percentages and tables were used to characterise variables. A chi-square test was used to explore associations between dependent and independent variables. Test significance, confidence intervals and p-values of all the causes and contributory factors were set at 0.05. Results: Thirty two percent reported having sex with multiple sexual partners while 19percent reported never using a condom. Forty eight percent reported having had sexually transmitted infections since starting on ART. The median age (36 years (IQR: 31, 45) vs. 35 years (IQR: 26, 40)) of those who reported STIs was higher than the median age of those who did not report STI (p=0.012). Males (57percent, p=0.049), those who were employed (55percent, p=0.048), and those who were cohabitating (68percent, 0.030) were more likely to report STI. Similarly, those who had unprotected sex with a casual partner (62percent, p<0.001), and those who did not use a condom because a partner did not like it (71percent, p=0.001) were more likely to report STIs. A significant number of 32percent of the participants reported engaging in risky sexual practices while 48percent had reported an STI. Recommendations include educational outreach programmes and capacitation of health care workers with appropriate skills and tools. , Thesis (MPH) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-07
Investigation of sediment buffering function of the Gatberg Floodplain Wetland in the upper Tsitsa River Catchment, South Africa
- Pakati, Sibuyisele Sweetness
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10
Investigation of the Chemical Nature and Species Distribution of Nitromethane in Inert Solvents
- Authors: Namntu, Vuyokozi
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2964 , vital:43106
- Description: The solution behaviour of nitromethane in inert solvents; carbon tetrachloride, n-hexane and cyclohexane is rigorously investigated using mainly spectroscopic and computational techniques. Analysis of Proton (1H) and Carbon 13 (13C) NMR spectral data reveal that nitromethane solutions in inert solvents form associated species to varying degrees of complexity. A cyclic dimer is postulated as the energetically most favourable chemical species at low solute concentrations. Infrared spectra studied in the overtone region and UV-Visible spectral data confirm the presence of multiple associated chemical species at different solute concentrations with the degree of association progressively increasing with increase in concentration of the solute. The species involved in the association of nitromethane is formulated as (CH3NO2)2n, where n=0, 1,2 and 3, for the monomer, dimer and higher order polymers respectively. Line-shape analysis of both infrared and UV spectra show the onset of a plateau at molar solute concentrations of 0.616 molar described by the point of inflection in the absorption curve at around 0.055 cm-1 , in the second overtone. , Thesis (MSc) -- Faculty of Natural Sciences, 2014
- Full Text:
- Date Issued: 2014
- Authors: Namntu, Vuyokozi
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2964 , vital:43106
- Description: The solution behaviour of nitromethane in inert solvents; carbon tetrachloride, n-hexane and cyclohexane is rigorously investigated using mainly spectroscopic and computational techniques. Analysis of Proton (1H) and Carbon 13 (13C) NMR spectral data reveal that nitromethane solutions in inert solvents form associated species to varying degrees of complexity. A cyclic dimer is postulated as the energetically most favourable chemical species at low solute concentrations. Infrared spectra studied in the overtone region and UV-Visible spectral data confirm the presence of multiple associated chemical species at different solute concentrations with the degree of association progressively increasing with increase in concentration of the solute. The species involved in the association of nitromethane is formulated as (CH3NO2)2n, where n=0, 1,2 and 3, for the monomer, dimer and higher order polymers respectively. Line-shape analysis of both infrared and UV spectra show the onset of a plateau at molar solute concentrations of 0.616 molar described by the point of inflection in the absorption curve at around 0.055 cm-1 , in the second overtone. , Thesis (MSc) -- Faculty of Natural Sciences, 2014
- Full Text:
- Date Issued: 2014
Investigation of the levels of PBDEs and PCNs in the surface water and sediments from selected waterbodies in the Eastern Cape Province, South Africa
- Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Authors: Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Date: 2021-06
- Subjects: Persistent pollutants , Water -- Purification -- Organic compounds removal , Organic water pollutants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22699 , vital:52660
- Description: Studies have revealed that persistent organic pollutants (POPs) are omnipresent in our environment; almost all human beings have definite levels of POPs in their bodies. Even fetus and embryos are not spared; they have been found to bear certain levels of POPs. So far, there are about 28 chemicals listed as POPs among which are polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs). PCN and PBDE distributions have been reported from different sources around the world, but studies relating to PCNs occurrence and distribution in Africa, especially South Africa is still minimal. PBDEs have been reported to cause diabetes, cancer, damage to reproductive system, thyroid, liver and other vital organs in the body, while PCNs have been linked to chloracne (severe skin reactions/lesions) and liver disease (yellow atrophy) in humans, chicken oedema and X-disease in cattle. Hence, this study evaluates PCN levels in water and sediment samples from three waterbodies: North End Lake (NEL), Chatty River (CHA) and Makman Canal (MMC), while PBDE levels was reported in NEL and CHA samples. The three sites are located in Port Elizabeth, Eastern Cape Province (ECP) of South Africa. The lake serves as a recreational resort while the latter two waterbodies are tributaries discharging into the Swartkop Estuary, an important estuary in ECP. Water samples were extracted with C18 cartridges (solid phase), while soxhlet was employed for the extraction of sediments. Water and sediment extricates were purified and quantified with gas chromatography-micro electron capture detector (GC-μECD). Forty-seven (47) water samples and 44 sediment samples were collected in August until December 2020 from six sampling points in NEL, five points in each of CHA and MMC. All the samples were evaluated for physicochemical properties, PBDEs and PCNs using validated standard methods. The sampling period covered three South Africa seasons: August (winter), October (spring) and December (summer). The physicochemical parameters (PP) of NEL water samples for the three seasons generally varied as follows: temperature (15.3–23°C), pH (7.9–10.3), oxidation-reduction potential, ORP (23.4-110 mV), atmospheric pressure, AP (14.52-15.56 PSI), turbidity (15.1–167 NTU), electrical conductivity, EC (114–1291 μS/cm), total dissolved solids, TDS (55-645 mg/L), total suspended solids, TSS (20–107 mg/L) and salinity (0.05–0.65 PSU). All the PPs except for turbidity and TSS are within acceptable limits. NEL sediments had moisture content (MC), organic matter (OM) and organic carbon (OC) in the range of 0.04–8.0percent, 0.08–2.2percent and 0.05–1.8percent, respectively. The sum of eight PCN congeners Σ8PCNs and six PBDE congeners Σ6PBDEs in NEL water samples ranged from 0.164–2.934 μg/L and 0.009-1.025 μg/L individually. The values for Σ8PCNs and Σ6PBDEs in NEL sediment samples varied from 0.991–237 μg/kg and 0.354-28.850 μg/kg, respectively. The calculated hazard quotient (HQ) corresponding to the non-carcinogenic health risk associated with PBDEs in NEL water samples was 2.0×10-3-1.4×10-1, while the TEQ values due to PCNs varied from 6.10×10-7- 3.12×10-3 μg/L in NEL water samples and 3.70×10-5-1.96×10-2 μg/kg dw in sediments. The PP values for CHA water samples include temperature (15.4–22.9°C), pH (7.7–10.5), TDS (991–1771 mg/L), TSS (6–41 mg/L), turbidity (1.0–198 NTU), EC (1981–3542 μS/cm), AP (14.60–14.80 PSI), ORP (-339.1-51.3 mV), and salinity (1.02–1.87 PSU). The EC, TDS and salinity exceeded acceptable values at certain points. The sediments of CHA have MC, OM and OC contents ranging from 0.01-10.2percent, 0.2-1.3percent and 0.1-0.8percent in that order. Sum of Σ8PCNs, Σ6PBDEs in CHA water and sediment samples ranged from 0.026–1.054 μg/L, 0.007-0.079 μg/L and 0.429–1888.468 μg/kg, 0.347-6.468 μg/kg individually. The HQ in CHA water samples was 1.6×10-3-7.7×10-3 and the estimated TEQ was 1.0×10-7-6.62×10-5 μg/L and 1.10×10−5-6.40×10−2 μg/kg in water and sediments, respectively. The temperatures for MMC water samples ranged from 15.6-24.5°C, while other PPs recorded were as follows: pH (8.4-10.2), TDS (943–4002 mg/L), TSS (7-491 mg/L), turbidity (2.9-154.2 NTU), EC (1885-8004 μS/cm), AP (14.53–14.82 PSI), ORP (7.8-130 mV) and salinity (0.96-4.47 PSU). MMC’s sediments recorded MC, OM and OC varying as 0.4- 18.9percent, 0.2-4.5percent and 0.1-2.6percent, respectively across the three seasons. The Σ8PCNs for MMC water and sediment samples were 0.035–0.699 μg/L and 0.260–6744 μg/kg. The TEQ values in MMC water and sediment samples were 1.19×10-7-1.47×10-4 μg/L and 4.43×10−5- 4.19×10−1 μg/kg, respectively. The results are all less than one, and this suggests that the selected water is safe. Results showed that NEL water had highest TEQ, PCN and PBDE concentrations, while MMC sediments recorded maximum TEQ and PCN levels in this study. PBDE concentrations in NEL sediments were above the other site. In conclusion, NEL water was most polluted with both pollutants (PCNs and PBDEs), but MMC sediments contained more PCNs. There is need for the immediate remediation of these selected waterbodies. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-06
- Authors: Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Date: 2021-06
- Subjects: Persistent pollutants , Water -- Purification -- Organic compounds removal , Organic water pollutants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22699 , vital:52660
- Description: Studies have revealed that persistent organic pollutants (POPs) are omnipresent in our environment; almost all human beings have definite levels of POPs in their bodies. Even fetus and embryos are not spared; they have been found to bear certain levels of POPs. So far, there are about 28 chemicals listed as POPs among which are polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs). PCN and PBDE distributions have been reported from different sources around the world, but studies relating to PCNs occurrence and distribution in Africa, especially South Africa is still minimal. PBDEs have been reported to cause diabetes, cancer, damage to reproductive system, thyroid, liver and other vital organs in the body, while PCNs have been linked to chloracne (severe skin reactions/lesions) and liver disease (yellow atrophy) in humans, chicken oedema and X-disease in cattle. Hence, this study evaluates PCN levels in water and sediment samples from three waterbodies: North End Lake (NEL), Chatty River (CHA) and Makman Canal (MMC), while PBDE levels was reported in NEL and CHA samples. The three sites are located in Port Elizabeth, Eastern Cape Province (ECP) of South Africa. The lake serves as a recreational resort while the latter two waterbodies are tributaries discharging into the Swartkop Estuary, an important estuary in ECP. Water samples were extracted with C18 cartridges (solid phase), while soxhlet was employed for the extraction of sediments. Water and sediment extricates were purified and quantified with gas chromatography-micro electron capture detector (GC-μECD). Forty-seven (47) water samples and 44 sediment samples were collected in August until December 2020 from six sampling points in NEL, five points in each of CHA and MMC. All the samples were evaluated for physicochemical properties, PBDEs and PCNs using validated standard methods. The sampling period covered three South Africa seasons: August (winter), October (spring) and December (summer). The physicochemical parameters (PP) of NEL water samples for the three seasons generally varied as follows: temperature (15.3–23°C), pH (7.9–10.3), oxidation-reduction potential, ORP (23.4-110 mV), atmospheric pressure, AP (14.52-15.56 PSI), turbidity (15.1–167 NTU), electrical conductivity, EC (114–1291 μS/cm), total dissolved solids, TDS (55-645 mg/L), total suspended solids, TSS (20–107 mg/L) and salinity (0.05–0.65 PSU). All the PPs except for turbidity and TSS are within acceptable limits. NEL sediments had moisture content (MC), organic matter (OM) and organic carbon (OC) in the range of 0.04–8.0percent, 0.08–2.2percent and 0.05–1.8percent, respectively. The sum of eight PCN congeners Σ8PCNs and six PBDE congeners Σ6PBDEs in NEL water samples ranged from 0.164–2.934 μg/L and 0.009-1.025 μg/L individually. The values for Σ8PCNs and Σ6PBDEs in NEL sediment samples varied from 0.991–237 μg/kg and 0.354-28.850 μg/kg, respectively. The calculated hazard quotient (HQ) corresponding to the non-carcinogenic health risk associated with PBDEs in NEL water samples was 2.0×10-3-1.4×10-1, while the TEQ values due to PCNs varied from 6.10×10-7- 3.12×10-3 μg/L in NEL water samples and 3.70×10-5-1.96×10-2 μg/kg dw in sediments. The PP values for CHA water samples include temperature (15.4–22.9°C), pH (7.7–10.5), TDS (991–1771 mg/L), TSS (6–41 mg/L), turbidity (1.0–198 NTU), EC (1981–3542 μS/cm), AP (14.60–14.80 PSI), ORP (-339.1-51.3 mV), and salinity (1.02–1.87 PSU). The EC, TDS and salinity exceeded acceptable values at certain points. The sediments of CHA have MC, OM and OC contents ranging from 0.01-10.2percent, 0.2-1.3percent and 0.1-0.8percent in that order. Sum of Σ8PCNs, Σ6PBDEs in CHA water and sediment samples ranged from 0.026–1.054 μg/L, 0.007-0.079 μg/L and 0.429–1888.468 μg/kg, 0.347-6.468 μg/kg individually. The HQ in CHA water samples was 1.6×10-3-7.7×10-3 and the estimated TEQ was 1.0×10-7-6.62×10-5 μg/L and 1.10×10−5-6.40×10−2 μg/kg in water and sediments, respectively. The temperatures for MMC water samples ranged from 15.6-24.5°C, while other PPs recorded were as follows: pH (8.4-10.2), TDS (943–4002 mg/L), TSS (7-491 mg/L), turbidity (2.9-154.2 NTU), EC (1885-8004 μS/cm), AP (14.53–14.82 PSI), ORP (7.8-130 mV) and salinity (0.96-4.47 PSU). MMC’s sediments recorded MC, OM and OC varying as 0.4- 18.9percent, 0.2-4.5percent and 0.1-2.6percent, respectively across the three seasons. The Σ8PCNs for MMC water and sediment samples were 0.035–0.699 μg/L and 0.260–6744 μg/kg. The TEQ values in MMC water and sediment samples were 1.19×10-7-1.47×10-4 μg/L and 4.43×10−5- 4.19×10−1 μg/kg, respectively. The results are all less than one, and this suggests that the selected water is safe. Results showed that NEL water had highest TEQ, PCN and PBDE concentrations, while MMC sediments recorded maximum TEQ and PCN levels in this study. PBDE concentrations in NEL sediments were above the other site. In conclusion, NEL water was most polluted with both pollutants (PCNs and PBDEs), but MMC sediments contained more PCNs. There is need for the immediate remediation of these selected waterbodies. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-06
Investigation of thermal and electrical characteristics of crystalline silicon photovoltaic modules under varying operational conditions
- Authors: Vumbugwa, Monphias
- Date: 2022-12
- Subjects: Photovoltaic power generation -- South Africa , Silicon crystals -- South Africa , Solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60014 , vital:62733
- Description: Solar energy has become an attractive and environmentally mindful method in electrical power generation as it contributes significantly to meeting the high demand for the power needed for socio and economic developments. The rise in deployment of Photovoltaic (PV) facilities with large capacity creates the need for accurate and reliable PV inspection techniques for optimum performance, the longevity of PV modules and quick return on PV investment. The performance of PV modules in the field is often monitored through several inspection methods that require a rapid throughput such as Thermal Infrared (TIR) imaging and current-voltage (I-V) measurements. Unmanned Aerial Vehicle (UAV) based TIR imaging is widely applied in large PV plants since it is cost-effective and is usually conducted in-situ while the plant is operating at irradiance levels above 600 W.m-2 . One of the outcomes of the interpretations of TIR images is an attempt to quantify the energy loss in PV plants associated with the abnormal thermal signatures identified on TIR images. No standard procedure has yet outlined the quantification of energy loss related to TIR images of underperforming modules since the interpretation of TIR images remains a challenge. PV modules operate under dynamic operating conditions which can influence the results and interpretation of thermal and electrical characterisation measurements. Dynamic operation conditions refer to any disorders in the operation of the modules and cells which cause a change in the current and voltage characteristics of the PV source. These dynamic operation conditions include; changesin load conditions, irradiance, soiling and shading levels. The tests were done under steady state conditions. Although measurements are generally done while the operating conditions are as steady as possible, some changes in conditions have a profound effect on thermal and electrical measurements. In this study, these effects and some of the changes in conditions that cause them were studied. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Vumbugwa, Monphias
- Date: 2022-12
- Subjects: Photovoltaic power generation -- South Africa , Silicon crystals -- South Africa , Solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60014 , vital:62733
- Description: Solar energy has become an attractive and environmentally mindful method in electrical power generation as it contributes significantly to meeting the high demand for the power needed for socio and economic developments. The rise in deployment of Photovoltaic (PV) facilities with large capacity creates the need for accurate and reliable PV inspection techniques for optimum performance, the longevity of PV modules and quick return on PV investment. The performance of PV modules in the field is often monitored through several inspection methods that require a rapid throughput such as Thermal Infrared (TIR) imaging and current-voltage (I-V) measurements. Unmanned Aerial Vehicle (UAV) based TIR imaging is widely applied in large PV plants since it is cost-effective and is usually conducted in-situ while the plant is operating at irradiance levels above 600 W.m-2 . One of the outcomes of the interpretations of TIR images is an attempt to quantify the energy loss in PV plants associated with the abnormal thermal signatures identified on TIR images. No standard procedure has yet outlined the quantification of energy loss related to TIR images of underperforming modules since the interpretation of TIR images remains a challenge. PV modules operate under dynamic operating conditions which can influence the results and interpretation of thermal and electrical characterisation measurements. Dynamic operation conditions refer to any disorders in the operation of the modules and cells which cause a change in the current and voltage characteristics of the PV source. These dynamic operation conditions include; changesin load conditions, irradiance, soiling and shading levels. The tests were done under steady state conditions. Although measurements are generally done while the operating conditions are as steady as possible, some changes in conditions have a profound effect on thermal and electrical measurements. In this study, these effects and some of the changes in conditions that cause them were studied. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-12
Investigation on the nature of records management in the office of the Premier Supply Chain management
- Authors: Vakalisa, Ndileka
- Date: 2017
- Subjects: Grahamstown (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27606 , vital:69319
- Description: The purpose of the study was to investigate on the nature of records management in the office of the Premier Supply Chain Management. This study focuses on the Supply Chain Unit in the office of the Premier in the Eastern Cape Province of South Africa. The study sought to investigate the classification systems in place that is records management policy, procedure manual and file plans. The legal framework that regulates archives. Data was collected using open-ended questionnaire. The target population of this study included all the officials within the Office of the Premier. The sample of 15 was derived from the supply chain management officials, records management managers and directors. The study adopted a qualitative research methodology, which is multimethod in its orientation, which involves an interpretative, naturalistic emphasis to its subject issue. Findings from the study revealed that the unit had its internal records management policy, an official framework document that outlined the processes involved in organising records within the department. Thus, there are policy frameworks within the department even though not clearly described to other employees, which might lead to risks in the management of records. The study also revealed that most records personnel were not trained to effectively manage records. It was also indicated that there is a lack of proper filing system and or electronic records management system. Hence, for effective and efficient records management, the study recommends the creation of a web-based integrated system for communication and where records can be accessed within one system. The study also recommends proper training of records personnel to mitigate risks. Hence, the study recommends that senior management create and implement a records management program that clearly outlines the procedures of records management, risks factors and how to minimize them. This will aide in good practice, uniformity, standardization, high levels of professionalism, accountability, and transparency. , Thesis (MLIS) -- Faculty of Social Sciences and Humanities, 2017
- Full Text:
- Date Issued: 2017
- Authors: Vakalisa, Ndileka
- Date: 2017
- Subjects: Grahamstown (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27606 , vital:69319
- Description: The purpose of the study was to investigate on the nature of records management in the office of the Premier Supply Chain Management. This study focuses on the Supply Chain Unit in the office of the Premier in the Eastern Cape Province of South Africa. The study sought to investigate the classification systems in place that is records management policy, procedure manual and file plans. The legal framework that regulates archives. Data was collected using open-ended questionnaire. The target population of this study included all the officials within the Office of the Premier. The sample of 15 was derived from the supply chain management officials, records management managers and directors. The study adopted a qualitative research methodology, which is multimethod in its orientation, which involves an interpretative, naturalistic emphasis to its subject issue. Findings from the study revealed that the unit had its internal records management policy, an official framework document that outlined the processes involved in organising records within the department. Thus, there are policy frameworks within the department even though not clearly described to other employees, which might lead to risks in the management of records. The study also revealed that most records personnel were not trained to effectively manage records. It was also indicated that there is a lack of proper filing system and or electronic records management system. Hence, for effective and efficient records management, the study recommends the creation of a web-based integrated system for communication and where records can be accessed within one system. The study also recommends proper training of records personnel to mitigate risks. Hence, the study recommends that senior management create and implement a records management program that clearly outlines the procedures of records management, risks factors and how to minimize them. This will aide in good practice, uniformity, standardization, high levels of professionalism, accountability, and transparency. , Thesis (MLIS) -- Faculty of Social Sciences and Humanities, 2017
- Full Text:
- Date Issued: 2017
Investigations into tolerance of quality protein maize germplasm to low soil pH.
- Authors: Mathiso, Ncebakazi
- Date: 2020-06
- Subjects: Proteins in human nutrition , Crops--Drought tolerance
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20804 , vital:46580
- Description: Quality protein maize (QPM) has double the amount of two crucial amino acids (tryptophan and lysine) compared to normal maize. These amino acids make QPM very nutritious and strategically important to overcoming malnutrition in communities that use maize as a staple food. However, QPM production is affected by many abiotic stress factors such as drought, salinity and low soil pH. Screening for tolerance to low soil pH was conducted in this study due to limited focus on this stress in previous QPM breeding efforts. The main objective of this study was to determine the response of QPM germplasm to low soil pH. The specific objectives were to: (i) screen QPM germplasm for tolerance to low soil pH at seedling stage; (ii) determine the combining ability and type of gene action controlling various traits of QPM inbred lines under low soil pH at seedling stage (iii) select QPM hybrids that are high yielding under limed and unlimed conditions, as well as across environments. This study was conducted in South Africa, at the University of Fort Hare and at Dohne Agricultural Development Institute. Screening of 21 QPM inbred lines and two testers under glasshouse conditions was conducted using a randomised complete block design (RCBD) with three replicates. In this experiment, maize germplasm were screened for tolerance to low soil pH at the early seedling stage. The soil had a pH of 4, and it was sourced from Hogsback, in the Eastern Cape. The control was obtained by liming this soil so as to increase the pH to 5.5. Seedling traits such as chlorophyll content, stem diameter, plant height, root to shoot ratio, total biomass as well number of leaves were recorded in both experiments. JMP statistical software, version 14, was used for analysis of variance (ANOVA) and generating descriptive statistics on the traits that were measured. All measured traits showed highly significant variation (p<0,0001) except for number of leaves in the glasshouse experiment. Two indices, namely Dickson quality index and acidic soil adaptation index, revealed that tolerant inbred lines were QSW 20, IBL 7, IBL 1, IBL 14 and NC. The same 21 inbred lines were evaluated in the laboratory using the haematoxylin assay. A RCBD with three replicates was used to screen the inbred lines for tolerance to Al toxicity. The genotypes were exposed to a nutrient solution that had 440 uM of Al3+ at a pH of 4 while the control used a nutrient solution without Al toxicity at a pH of 5.8. Net root growth, relative root growth, total biomass and haematoxylin scoring were measured. All these parameters showed significant differences (p< 0,0001). The haematoxylin scoring and other measured traits were used to effectively assess the tolerance of inbred lines to Al toxicity. Inbred lines QSW 32, QSW 20, QSW 1, QSW 6 and IBL 1 were tolerant to Al toxicity. Combining ability of parental inbred lines and testers was evaluated for various traits under limed, unlimed as well as across (both limed and unlimed) environments in a glasshouse experiment. Line x tester hybrids and parental lines were evaluated in a RCBD with three replicates. The results showed that both additive and non-additive gene action influenced the expression of measured traits in all the environments. However, total dry weight was controlled by additive gene action in all the environments. There were no parents that showed good GCA for total dry weight under limed environments whereas inbred lines 17,15, 14, 1 and 20 had high GCA values for TDW under unlimed conditions. Moreover, across the environments, lines 21 and 14 showed good GCA for total dry weight. On the other hand, among the tescross hybrids evaluated under limed environment, seven hybrids had very high SCA values, while hybrids 10 x 20 and 6 x 20 showed best SCA for TDW under unlimed conditions. Under both limed and unlimed environments, hybrids with good SCA for TDW were 11 x 21 and 12 x 21. Forty testcross hybrids were assessed for yield potential under limed and unlimed conditions in the field using a RCBD with three replicates. The SAS version 9.2 was used for analysis of variance. Standard morphological traits measured showed significant differences under unlimed and limed conditions. Genotype OBT x IBL 2 had high grain yields, low yield reduction, a short anthesis-siking interval under low soil pH, and it was tolerant. On the other hand, genotypes NC, NC x IBL 6 and OBT x QSW 6 exhibited the best yield stability across across environments. These genotypes are recommended for further evaluation to ascertain their yield potential and stability of performance in multi-locational soil acidity hot spots. , Thesis (MSc) (Crop Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2020-06
- Authors: Mathiso, Ncebakazi
- Date: 2020-06
- Subjects: Proteins in human nutrition , Crops--Drought tolerance
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20804 , vital:46580
- Description: Quality protein maize (QPM) has double the amount of two crucial amino acids (tryptophan and lysine) compared to normal maize. These amino acids make QPM very nutritious and strategically important to overcoming malnutrition in communities that use maize as a staple food. However, QPM production is affected by many abiotic stress factors such as drought, salinity and low soil pH. Screening for tolerance to low soil pH was conducted in this study due to limited focus on this stress in previous QPM breeding efforts. The main objective of this study was to determine the response of QPM germplasm to low soil pH. The specific objectives were to: (i) screen QPM germplasm for tolerance to low soil pH at seedling stage; (ii) determine the combining ability and type of gene action controlling various traits of QPM inbred lines under low soil pH at seedling stage (iii) select QPM hybrids that are high yielding under limed and unlimed conditions, as well as across environments. This study was conducted in South Africa, at the University of Fort Hare and at Dohne Agricultural Development Institute. Screening of 21 QPM inbred lines and two testers under glasshouse conditions was conducted using a randomised complete block design (RCBD) with three replicates. In this experiment, maize germplasm were screened for tolerance to low soil pH at the early seedling stage. The soil had a pH of 4, and it was sourced from Hogsback, in the Eastern Cape. The control was obtained by liming this soil so as to increase the pH to 5.5. Seedling traits such as chlorophyll content, stem diameter, plant height, root to shoot ratio, total biomass as well number of leaves were recorded in both experiments. JMP statistical software, version 14, was used for analysis of variance (ANOVA) and generating descriptive statistics on the traits that were measured. All measured traits showed highly significant variation (p<0,0001) except for number of leaves in the glasshouse experiment. Two indices, namely Dickson quality index and acidic soil adaptation index, revealed that tolerant inbred lines were QSW 20, IBL 7, IBL 1, IBL 14 and NC. The same 21 inbred lines were evaluated in the laboratory using the haematoxylin assay. A RCBD with three replicates was used to screen the inbred lines for tolerance to Al toxicity. The genotypes were exposed to a nutrient solution that had 440 uM of Al3+ at a pH of 4 while the control used a nutrient solution without Al toxicity at a pH of 5.8. Net root growth, relative root growth, total biomass and haematoxylin scoring were measured. All these parameters showed significant differences (p< 0,0001). The haematoxylin scoring and other measured traits were used to effectively assess the tolerance of inbred lines to Al toxicity. Inbred lines QSW 32, QSW 20, QSW 1, QSW 6 and IBL 1 were tolerant to Al toxicity. Combining ability of parental inbred lines and testers was evaluated for various traits under limed, unlimed as well as across (both limed and unlimed) environments in a glasshouse experiment. Line x tester hybrids and parental lines were evaluated in a RCBD with three replicates. The results showed that both additive and non-additive gene action influenced the expression of measured traits in all the environments. However, total dry weight was controlled by additive gene action in all the environments. There were no parents that showed good GCA for total dry weight under limed environments whereas inbred lines 17,15, 14, 1 and 20 had high GCA values for TDW under unlimed conditions. Moreover, across the environments, lines 21 and 14 showed good GCA for total dry weight. On the other hand, among the tescross hybrids evaluated under limed environment, seven hybrids had very high SCA values, while hybrids 10 x 20 and 6 x 20 showed best SCA for TDW under unlimed conditions. Under both limed and unlimed environments, hybrids with good SCA for TDW were 11 x 21 and 12 x 21. Forty testcross hybrids were assessed for yield potential under limed and unlimed conditions in the field using a RCBD with three replicates. The SAS version 9.2 was used for analysis of variance. Standard morphological traits measured showed significant differences under unlimed and limed conditions. Genotype OBT x IBL 2 had high grain yields, low yield reduction, a short anthesis-siking interval under low soil pH, and it was tolerant. On the other hand, genotypes NC, NC x IBL 6 and OBT x QSW 6 exhibited the best yield stability across across environments. These genotypes are recommended for further evaluation to ascertain their yield potential and stability of performance in multi-locational soil acidity hot spots. , Thesis (MSc) (Crop Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2020-06