A mobile based control system for smart homes
- Authors: Tshimanga, Danny Kazadi
- Date: 2022-03
- Subjects: Smart power grids , Home automation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22632 , vital:52606
- Description: A Smart Home Control System can provide a secure home, convenience, comfort, and interactivity of life in a particular home. The system can enable the automatic controlling of a house via a Smart Phone. These systems are becoming vital and widely used in homes to improve conditions of life. Most commercial home automation systems are expensive and their maintenance would require experts who understand the underlying implementation of the systems. This study developed a mobile-based home automation system prototype. The system was developed using the waterfall model methodology. To evaluate the developed system, the study used a simulation method. Ten trials were conducted to determine the performance of the implemented system. The mean time to failure was used to evaluate the system’ reliability. The system’s performance analysis revealed that the developed system performed better than the two other approaches; the Bluetooth and ZigBee. The developed system showed a 0 percent error, while the Bluetooth had 8 percent error and ZigBee 6 percent error. The reliability results showed the average lifespan of assets in the system before they could fail. Knowing the lifespan of an asset before it fails can help in reducing downtime of the system by planning or scheduling maintenance and develop an improved maintenance strategy. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2022-03
- Authors: Tshimanga, Danny Kazadi
- Date: 2022-03
- Subjects: Smart power grids , Home automation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22632 , vital:52606
- Description: A Smart Home Control System can provide a secure home, convenience, comfort, and interactivity of life in a particular home. The system can enable the automatic controlling of a house via a Smart Phone. These systems are becoming vital and widely used in homes to improve conditions of life. Most commercial home automation systems are expensive and their maintenance would require experts who understand the underlying implementation of the systems. This study developed a mobile-based home automation system prototype. The system was developed using the waterfall model methodology. To evaluate the developed system, the study used a simulation method. Ten trials were conducted to determine the performance of the implemented system. The mean time to failure was used to evaluate the system’ reliability. The system’s performance analysis revealed that the developed system performed better than the two other approaches; the Bluetooth and ZigBee. The developed system showed a 0 percent error, while the Bluetooth had 8 percent error and ZigBee 6 percent error. The reliability results showed the average lifespan of assets in the system before they could fail. Knowing the lifespan of an asset before it fails can help in reducing downtime of the system by planning or scheduling maintenance and develop an improved maintenance strategy. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2022-03
Assessment of soil erosion based on clustered geoinformatics approaches: a case study of Tyume River Catchment, Eastern Cape, South Africa
- Mbatyoti, Siyanda https://orcid.org/0000-0002-9736-5684
- Authors: Mbatyoti, Siyanda https://orcid.org/0000-0002-9736-5684
- Date: 2022-03
- Subjects: Soil erosion , Geoinformatics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22852 , vital:52969
- Description: This research centres on the holistic assessments of spatial and temporal dimensions of soil erosion zones based on the parameters of geomorphometry, hydro-statistics, and land use/cover dynamics. The study used a case study approach based on a clustered framework model of soil erosion parameters in the Tyume River basin in Eastern Cape, South Africa. The methods adopted for the investigation are, namely; non-parametric time-series assessment of streamflow dataset, semidecadal assessment of land use/cover (LU/C) dynamics, geospatial analysis of geomorphometric variables, vulnerability analysis of soil erosion zones, regression analysis of determination coefficient, and Receiver Operating Characteristic Curve (ROC). The delineation of soil erosion zones was based on the integrated analysis of the parameters of geomorphometry, geology, hydrology, and land use/ cover. The result of the hydro-statistical analysis of the Tyume River reports a major decline in the inter-annual regime frequency of storm flow based on the Mann- Kendall (MK) test and Sen’s slope assessment in 1992 (p-value = 0.031), 1997 (p-value = 0.045), 2003 (p-value = 0.021), 2008 (p-value = 0.003), and 2016 (p-value = 0.002). The MK test depicted a recurrence of peak streamflow acceleration in every three years based on low-flow and highflow transition. The sensitivity of LU/C to temporal dynamics of streamflow trends shown by the coefficient of correlation of trends of the LU/C water bodies with streamflow semi-decadal acceleration indicates a moderately relevant relationship, R = 0.76. The temporal analysis of LU/C and hydro-statistical analysis shows that the Tyume basin was highly vulnerable to soil erosion by water in 1999, 2009, and 2019. The vulnerability of the Tyume River basin in 2019 is exceptional and this is due to the conversion of forested area (woodland) into a built-up environment and farmland, with a high vulnerability in 2019 due to the slump in the rate of change of woodland and precipitation, and the increase in the rate of built-up and agricultural activities. The soil erosion vulnerability mapping divides the river basin into the critical high, high, moderate, low, nonvulnerable zones that cover 40 km2, 135 km2, 209 km2, and 186 km2 respectively. Regression analysis shows that the areas of soil erosion in the Tyume basin are moderately represented by the model (R2 = 56) while the model performance assessment based on success rate and prediction rate estimation from the area under the ROC curve shows that the model is good, Area Under Curve of the ROC = 0.899, and 0.897. The analysis suggests that soil erosion is driven by the impact of land use/land cover change, particularly in areas of high drainage density. Significantly, high vegetation density played a vital role in lowering high-flow on the hill-slope and low topographic wetness area as well as in areas with erodible geologic properties. The study, therefore, recommends the advocacy of crop rotation method of agricultural practice in the highly critical areas of soil erosion and recommends the development of riparian forests around the Tyume River. The study provides important information for environmental stakeholders on degradable areas which may require the urgent implementation of sustainable development measures. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Mbatyoti, Siyanda https://orcid.org/0000-0002-9736-5684
- Date: 2022-03
- Subjects: Soil erosion , Geoinformatics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22852 , vital:52969
- Description: This research centres on the holistic assessments of spatial and temporal dimensions of soil erosion zones based on the parameters of geomorphometry, hydro-statistics, and land use/cover dynamics. The study used a case study approach based on a clustered framework model of soil erosion parameters in the Tyume River basin in Eastern Cape, South Africa. The methods adopted for the investigation are, namely; non-parametric time-series assessment of streamflow dataset, semidecadal assessment of land use/cover (LU/C) dynamics, geospatial analysis of geomorphometric variables, vulnerability analysis of soil erosion zones, regression analysis of determination coefficient, and Receiver Operating Characteristic Curve (ROC). The delineation of soil erosion zones was based on the integrated analysis of the parameters of geomorphometry, geology, hydrology, and land use/ cover. The result of the hydro-statistical analysis of the Tyume River reports a major decline in the inter-annual regime frequency of storm flow based on the Mann- Kendall (MK) test and Sen’s slope assessment in 1992 (p-value = 0.031), 1997 (p-value = 0.045), 2003 (p-value = 0.021), 2008 (p-value = 0.003), and 2016 (p-value = 0.002). The MK test depicted a recurrence of peak streamflow acceleration in every three years based on low-flow and highflow transition. The sensitivity of LU/C to temporal dynamics of streamflow trends shown by the coefficient of correlation of trends of the LU/C water bodies with streamflow semi-decadal acceleration indicates a moderately relevant relationship, R = 0.76. The temporal analysis of LU/C and hydro-statistical analysis shows that the Tyume basin was highly vulnerable to soil erosion by water in 1999, 2009, and 2019. The vulnerability of the Tyume River basin in 2019 is exceptional and this is due to the conversion of forested area (woodland) into a built-up environment and farmland, with a high vulnerability in 2019 due to the slump in the rate of change of woodland and precipitation, and the increase in the rate of built-up and agricultural activities. The soil erosion vulnerability mapping divides the river basin into the critical high, high, moderate, low, nonvulnerable zones that cover 40 km2, 135 km2, 209 km2, and 186 km2 respectively. Regression analysis shows that the areas of soil erosion in the Tyume basin are moderately represented by the model (R2 = 56) while the model performance assessment based on success rate and prediction rate estimation from the area under the ROC curve shows that the model is good, Area Under Curve of the ROC = 0.899, and 0.897. The analysis suggests that soil erosion is driven by the impact of land use/land cover change, particularly in areas of high drainage density. Significantly, high vegetation density played a vital role in lowering high-flow on the hill-slope and low topographic wetness area as well as in areas with erodible geologic properties. The study, therefore, recommends the advocacy of crop rotation method of agricultural practice in the highly critical areas of soil erosion and recommends the development of riparian forests around the Tyume River. The study provides important information for environmental stakeholders on degradable areas which may require the urgent implementation of sustainable development measures. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
Effects of climatic variability on maize productivity in South Africa from 1937-2018
- Awum Awum, Rudin https://orcid.org/ 0000-0002-8740-6163
- Authors: Awum Awum, Rudin https://orcid.org/ 0000-0002-8740-6163
- Date: 2022-03
- Subjects: Crops and climate , Climatic changes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/21410 , vital:48576
- Description: Climate is an important factor in agricultural production. The world is facing climate change and variability, which result in high temperatures, low rainfall patterns, shortage of water and persistent droughts. Climate change poses a significant threat to South Africa’s water resources, food security, health, infrastructure, ecosystem services and biodiversity. Negative impacts of climate variability on agriculture, especially on maize the staple crop, will worsen the food security status of the nation as most of South Africa’s maize crop is produced in summer and highly depends on rainfall. This study attempted to assess the impact of climate on maize production in South Africa using secondary time series data for the period 1937 to 2018. Rainfall and temperature were used as proxies for climate variability. The Granger Causality Model was used to examine the causal linkages between climatic variables (temperature or rainfall) and maize output in South Africa for the study period. The major outcome of the analysis was that there is a two-way causal relationship between maize production and temperature. The results also indicated that there is uni-directional causality between maize yield and rainfall. Furthermore, the Variance Decomposition Model was used to forecast the relationship between climatic elements and maize production in South Africa. The result showed that all variables have an effect on maize yield, with temperature having the least effect. The last objective of the study was to profile the maize output trend for the period from 1937 to 2018. The main findings from the analysis indicate that maize production in South Africa has a general upward slope. The study recommends that the government should intensify the provision of irrigation systems for the farmers in the most vulnerable areas to mitigate the climate change. Government should also embark on massive campaigns using a variety of media to create the needed public awareness on climate change and its impact on food security. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Awum Awum, Rudin https://orcid.org/ 0000-0002-8740-6163
- Date: 2022-03
- Subjects: Crops and climate , Climatic changes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/21410 , vital:48576
- Description: Climate is an important factor in agricultural production. The world is facing climate change and variability, which result in high temperatures, low rainfall patterns, shortage of water and persistent droughts. Climate change poses a significant threat to South Africa’s water resources, food security, health, infrastructure, ecosystem services and biodiversity. Negative impacts of climate variability on agriculture, especially on maize the staple crop, will worsen the food security status of the nation as most of South Africa’s maize crop is produced in summer and highly depends on rainfall. This study attempted to assess the impact of climate on maize production in South Africa using secondary time series data for the period 1937 to 2018. Rainfall and temperature were used as proxies for climate variability. The Granger Causality Model was used to examine the causal linkages between climatic variables (temperature or rainfall) and maize output in South Africa for the study period. The major outcome of the analysis was that there is a two-way causal relationship between maize production and temperature. The results also indicated that there is uni-directional causality between maize yield and rainfall. Furthermore, the Variance Decomposition Model was used to forecast the relationship between climatic elements and maize production in South Africa. The result showed that all variables have an effect on maize yield, with temperature having the least effect. The last objective of the study was to profile the maize output trend for the period from 1937 to 2018. The main findings from the analysis indicate that maize production in South Africa has a general upward slope. The study recommends that the government should intensify the provision of irrigation systems for the farmers in the most vulnerable areas to mitigate the climate change. Government should also embark on massive campaigns using a variety of media to create the needed public awareness on climate change and its impact on food security. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
Organophosphate flame retardant’s signatures in the Buffalo River Estuary and their removal using modified cyclodextrins
- Authors: Bika, Sinozuko Hope
- Date: 2022-03
- Subjects: Water purification chemicals industry , Organic water pollutants , Rivers
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27500 , vital:67363
- Description: The increasing scarcity of fresh and clean water in many places around the world is a major concern. Water is a basic need that must be availed to humans, plants and animals at any given time. It is a requirement that each human on earth should get between 20-50 L of fresh, clean and pure water a day. It is very difficult to keep up with this need due to drastic increase in global pollution by emerging contaminants. The increase is due to human activities, modern way of life, industrialization and improper disposal of materials that contain these OPFRs. Organophosphate flame retardants OPFRs are the organic pollutants considered in this study. OPFRs are semi volatile compounds SVOCs that are used in many industries as flame retardants and additives. They were developed because of environmental and health concerns of previously used brominated and chlorinated flame retardants FRs. They show acute toxicity and exhibit adverse effects such as neurotoxicity, they are also carcinogenic to humans and animals. In recent years, some researchers have started investigating the occurrence and distribution of OPFRs in South African rivers. The aim of this study was to identify signatures of OPFRs in the aquatic environment of Buffalo River Estuary, and soil from a nearby dumpsite: and to develop a method for their removal using modified cyclodextrins. In this study, the concentration of OPFRs were investigated in sediments and soil samples collected from Buffalo River Estuary. This estuary is located close to a major port in East London city in the Eastern Cape Province, South Africa. Collection of samples was done across two seasons i.e. winter and spring. OPFRs in sediment and soil samples in this study were extracted using ultrasonic extraction method. Solid-phase extraction SPE was employed for the cleanup of the extracts, in order to reduce potential matrix interference and also for sample purification. The congeners of interest in this study were Tris 2-Choroethyl phosphate TCEP and Tris 1,3-Dicloro-2-propyl phosphate (TDCP). Samples were air dried immediately on arrival at the laboratory after being stored in an ice chest at 4 ℃ and further processed for further analysis.The concentrations of OPFRs were determined using GC-μECD (gas chromatograph coupled with micro electron capture detector) from soil and sediments in that area and they were found high in winter compared to spring owing to high level of discharge of industrial and domestic waste into the aquatic system and also the nearby dumpsite. The total concentrationof OPFRs Ʃ 2OPFRs for sediments and soil for both seasons was 39935±7619 μg/g and 10376±601 μg/g, respectively. The dominant congener in the Buffalo River Estuary was TCEP. The ecological risk assessment was estimated for the study area, and TCEP moderate risk while TDCP presented low risk. From this study, it could be inferred that the Buffalo River Estuary and the nearby dumpsite in East London are polluted by emerging pollutants i.e. OPFRs. Hence, strict control measures should be put in place to monitor all activities contributing to such magnitude of pollution in the estuary, which is of great economic value to the country. Furthermore in this study, an insoluble and hydrophilic polymer EDTA-Cysteine-β-Cyclodextrin was prepared and synthesized for the remediation of OPFRs in soil and sediments. This newly developed method was tested for the removal of TDCP an OPFR congener and it was successful with an average removal rate of 77.49 percent. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Bika, Sinozuko Hope
- Date: 2022-03
- Subjects: Water purification chemicals industry , Organic water pollutants , Rivers
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27500 , vital:67363
- Description: The increasing scarcity of fresh and clean water in many places around the world is a major concern. Water is a basic need that must be availed to humans, plants and animals at any given time. It is a requirement that each human on earth should get between 20-50 L of fresh, clean and pure water a day. It is very difficult to keep up with this need due to drastic increase in global pollution by emerging contaminants. The increase is due to human activities, modern way of life, industrialization and improper disposal of materials that contain these OPFRs. Organophosphate flame retardants OPFRs are the organic pollutants considered in this study. OPFRs are semi volatile compounds SVOCs that are used in many industries as flame retardants and additives. They were developed because of environmental and health concerns of previously used brominated and chlorinated flame retardants FRs. They show acute toxicity and exhibit adverse effects such as neurotoxicity, they are also carcinogenic to humans and animals. In recent years, some researchers have started investigating the occurrence and distribution of OPFRs in South African rivers. The aim of this study was to identify signatures of OPFRs in the aquatic environment of Buffalo River Estuary, and soil from a nearby dumpsite: and to develop a method for their removal using modified cyclodextrins. In this study, the concentration of OPFRs were investigated in sediments and soil samples collected from Buffalo River Estuary. This estuary is located close to a major port in East London city in the Eastern Cape Province, South Africa. Collection of samples was done across two seasons i.e. winter and spring. OPFRs in sediment and soil samples in this study were extracted using ultrasonic extraction method. Solid-phase extraction SPE was employed for the cleanup of the extracts, in order to reduce potential matrix interference and also for sample purification. The congeners of interest in this study were Tris 2-Choroethyl phosphate TCEP and Tris 1,3-Dicloro-2-propyl phosphate (TDCP). Samples were air dried immediately on arrival at the laboratory after being stored in an ice chest at 4 ℃ and further processed for further analysis.The concentrations of OPFRs were determined using GC-μECD (gas chromatograph coupled with micro electron capture detector) from soil and sediments in that area and they were found high in winter compared to spring owing to high level of discharge of industrial and domestic waste into the aquatic system and also the nearby dumpsite. The total concentrationof OPFRs Ʃ 2OPFRs for sediments and soil for both seasons was 39935±7619 μg/g and 10376±601 μg/g, respectively. The dominant congener in the Buffalo River Estuary was TCEP. The ecological risk assessment was estimated for the study area, and TCEP moderate risk while TDCP presented low risk. From this study, it could be inferred that the Buffalo River Estuary and the nearby dumpsite in East London are polluted by emerging pollutants i.e. OPFRs. Hence, strict control measures should be put in place to monitor all activities contributing to such magnitude of pollution in the estuary, which is of great economic value to the country. Furthermore in this study, an insoluble and hydrophilic polymer EDTA-Cysteine-β-Cyclodextrin was prepared and synthesized for the remediation of OPFRs in soil and sediments. This newly developed method was tested for the removal of TDCP an OPFR congener and it was successful with an average removal rate of 77.49 percent. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
Perceptions and determinants of genetically modified (GM) maize production among rural households: The case of Ngqushwa Local Municipality, South Africa
- Zamisa, Owethu https://orcid.org/0000-0002-7303-4469
- Authors: Zamisa, Owethu https://orcid.org/0000-0002-7303-4469
- Date: 2022-03
- Subjects: Genetically modified foods , Agricultural biotechnology , Sustainable agriculture -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22479 , vital:52343
- Description: Rural South Africa is faced with immense challenges including poverty, unemployment, low agriculture productivity, food and nutritional insecurity and inequalities. Against this background, enhancing rural agricultural productivity using proven technologies such as genetically modified (GM) maize production is suggested as a pathway to economic development and poverty reduction. Literature suggests that GM technology can increase crop yields, drought tolerance, reduced weeding labour costs and chemical spray costs. However, GM maize varieties available on the market currently were created to fit large-scale, capital-intensive, industrialised, and economically oriented agricultural systems. As a result, their uptake has been significantly slow especially in rural areas where several stakeholders are now questioning the potential of GM technology. With that background, this study aimed to understand determinants of gm maize production among rural farming households and their perceptions using the case of Ngqushwa Local Municipality. Specifically, the study sought to analyse types of maize varieties grown by rural households, associated yields, area allocation, rural households’ perceptions of GM maize, and to estimate factors that influence GM maize awareness, participation and intensity of production among this subsector. Using a cross-sectional survey research design, a sample size of 400 households was randomly selected and interviewed using a semi-structured questionnaire. The types of maize varieties grown by rural households, associated yields, area allocation and rural households’ perceptions of GM maize were analysed using descriptive statistics. Factors that influence GM maize awareness, participation, and intensity of production were estimated using a triple hurdle model where the 1st and 2nd hurdle were estimated using Probit regression, and 3rd hurdle a Tobit regression. The study revealed that landrace maize varieties are currently the most popular maize varieties grown by the majority of rural farming households from the study area producing higher yields (0.6t/ha) as compared to other hybrids (GM – 0.5t/ha, conventional hybrids -0.3t/ha and improved OPVs – 0.1t/ha). Descriptive statistics results also indicated that farming households from the study area allocated more land to landrace maize varieties (42percent) compared to other maize varieties (GM maize (30percent), hybrids (21percent) and improved OPVs (7percent) further supporting the notion that landrace maize varieties dominate the rural farming subsector. Perception results revealed that the majority (57percent) of the households perceived GM maize as an expensive variety which, however, has a potential to produce relatively higher yields than other hybrids on the market and eliminates several production problems (manual weeding, pest spraying) making farm management easier. Findings further indicate that the majority (52percent) of the farming households from the study area did not have sufficient knowledge of GM maize. Econometrics results revealed that GM maize awareness is negatively influenced by age and gender and positively influenced by marital status, employment status and number of years in school. Conditional on awareness of GM maize varieties, both participation and intensity of participation in GM maize production are positively influenced by land size, gender, group membership, size of arable land and negatively influenced by employment status and income. Against this background, the study concludes that farming households from the study area produced more compared to the other varieties. Furthermore, the study concludes that households get higher yields from landrace maize varieties and allocate more of their land to landrace maize production. In addition, the study also concludes that most rural farmers perceive participation in GM maize as beneficial especially towards elimination of farm management problems, produces higher yields, and makes farm management easier. Lastly, the study concludes that GM maize awareness is negatively influenced by age and gender and positively influenced by marital status, employment status and number of years in school. Both participation and intensity of participation in GM maize production are positively influenced by land size, gender, group membership, arable land and negatively influenced by employment status and income. The study recommends that priority should be given to these socio-economic and institutional factors and this may be addressed by targeting GM maize awareness campaigns and platforms more suited to female-headed, older, lowly educated and unemployed rural farming households. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Zamisa, Owethu https://orcid.org/0000-0002-7303-4469
- Date: 2022-03
- Subjects: Genetically modified foods , Agricultural biotechnology , Sustainable agriculture -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22479 , vital:52343
- Description: Rural South Africa is faced with immense challenges including poverty, unemployment, low agriculture productivity, food and nutritional insecurity and inequalities. Against this background, enhancing rural agricultural productivity using proven technologies such as genetically modified (GM) maize production is suggested as a pathway to economic development and poverty reduction. Literature suggests that GM technology can increase crop yields, drought tolerance, reduced weeding labour costs and chemical spray costs. However, GM maize varieties available on the market currently were created to fit large-scale, capital-intensive, industrialised, and economically oriented agricultural systems. As a result, their uptake has been significantly slow especially in rural areas where several stakeholders are now questioning the potential of GM technology. With that background, this study aimed to understand determinants of gm maize production among rural farming households and their perceptions using the case of Ngqushwa Local Municipality. Specifically, the study sought to analyse types of maize varieties grown by rural households, associated yields, area allocation, rural households’ perceptions of GM maize, and to estimate factors that influence GM maize awareness, participation and intensity of production among this subsector. Using a cross-sectional survey research design, a sample size of 400 households was randomly selected and interviewed using a semi-structured questionnaire. The types of maize varieties grown by rural households, associated yields, area allocation and rural households’ perceptions of GM maize were analysed using descriptive statistics. Factors that influence GM maize awareness, participation, and intensity of production were estimated using a triple hurdle model where the 1st and 2nd hurdle were estimated using Probit regression, and 3rd hurdle a Tobit regression. The study revealed that landrace maize varieties are currently the most popular maize varieties grown by the majority of rural farming households from the study area producing higher yields (0.6t/ha) as compared to other hybrids (GM – 0.5t/ha, conventional hybrids -0.3t/ha and improved OPVs – 0.1t/ha). Descriptive statistics results also indicated that farming households from the study area allocated more land to landrace maize varieties (42percent) compared to other maize varieties (GM maize (30percent), hybrids (21percent) and improved OPVs (7percent) further supporting the notion that landrace maize varieties dominate the rural farming subsector. Perception results revealed that the majority (57percent) of the households perceived GM maize as an expensive variety which, however, has a potential to produce relatively higher yields than other hybrids on the market and eliminates several production problems (manual weeding, pest spraying) making farm management easier. Findings further indicate that the majority (52percent) of the farming households from the study area did not have sufficient knowledge of GM maize. Econometrics results revealed that GM maize awareness is negatively influenced by age and gender and positively influenced by marital status, employment status and number of years in school. Conditional on awareness of GM maize varieties, both participation and intensity of participation in GM maize production are positively influenced by land size, gender, group membership, size of arable land and negatively influenced by employment status and income. Against this background, the study concludes that farming households from the study area produced more compared to the other varieties. Furthermore, the study concludes that households get higher yields from landrace maize varieties and allocate more of their land to landrace maize production. In addition, the study also concludes that most rural farmers perceive participation in GM maize as beneficial especially towards elimination of farm management problems, produces higher yields, and makes farm management easier. Lastly, the study concludes that GM maize awareness is negatively influenced by age and gender and positively influenced by marital status, employment status and number of years in school. Both participation and intensity of participation in GM maize production are positively influenced by land size, gender, group membership, arable land and negatively influenced by employment status and income. The study recommends that priority should be given to these socio-economic and institutional factors and this may be addressed by targeting GM maize awareness campaigns and platforms more suited to female-headed, older, lowly educated and unemployed rural farming households. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
Synthesis and evaluation of pyrene grafted onto zinc oxide nanoparticles for the removal of organic contaminants from wastewater
- Authors: Samuel, Zipho
- Date: 2022-03
- Subjects: Land treatment of wastewater , Zinc oxide , Water pollution control industry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27754 , vital:69407
- Description: Drinking water scarcity is a global crisis even though water covers about three quarters of the earth. One of the major causes of this scarcity is water pollution, which is a result of human activities. This has been noticed and reported for a number of years but is still unsolved and intensifying. Hence, scientists are busy trying to find solutions to this global menace. In this study, zinc oxide nanoparticles were synthesised via co-precipitation, a cost reasonable method and functionalized by grafting a pyrene ligand on its surface in order to provide a scaffold to which many other functionalities can be adsorbed. By so doing, the efficiency and capacity of bare nanoparticles is improved. The synthesised pyrene ligand was successfully characterised with nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscope (FTIR). The adsorbent was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, energy dispersive x-ray (EDX) and thermogravimetric analyzer (TGA). The choice of zinc oxide nanoparticles as preferred adsorbent was due to their exceptional properties including large surface area, thermal and chemical stabilities. These properties are the reason zinc oxide nanoparticles possess high adsorption efficiency and capacity. The results of characterization indicated a decreased particle size and improved thermal stabilities of the pyrene grafted zinc oxide nanoparticles compared to the zinc oxide nanoparticles, showing that this material can be employed even at higher temperatures. The average particle size of the bare nanoparticles decreased from 290 to 181 nm after functionalization. Thermal stability increased from 550oC in the bare nanoparticles to 650oC in the functionalized nanoparticles. Characteristic reflections of zinc oxide nanoparticles in the XRD analysis were maintained even after functionalization However, diffractogram roughness was noticed for the functionalized nanoparticles due to the introduction of the amorphous layer from the ligand. This novel material was employed for the removal of an herbicide, simazine as well as two dyes, methyl violet and brilliant green from aqueous solutions by batch adsorption experiments. The kinetics and isotherm studies of the different adsorption processes were carried out by using three of the commonly used kinetic and isotherm models (pseudo-first order, intraparticle diffusion and pseudo-second order) and (Langmuir, Temkin isotherms and Freundlich) respectively. From all batch adsorption experiments conducted for simazine removal, the adsorbent showed effectiveness and high adsorption capacity for the removal of simazine. The highest observed efficiency and capacity were 71.3 percent and 137 mg/g respectively at pH equals 2, time equals 60 minutes, adsorbent dose equals 20 mg and adsorbate conc equals 0. 281 mg/L. Kinetics study for the adsorption of simazine favoured pseudo-first order. However, Langmuir isotherm could also be applicable to understand the adsorption process. The material also showed reusability potential of up to three cycles for this contaminant indicating that this material can be re-used. In the case of the removal of methyl violet from aqueous solution, the adsorbent showed a reasonable adsorption maximum capacity (qmax) (31.5 mg/g) at contact time equals 360 min, adsorbent dose approximately equals 40 mg, temperature equals 20 plus 2oC and pH equals 6.5, when compared to other adsorbents previously reported for the removal of methyl violet (MV) in literature. Kinetics and isotherm studies indicated that the process for the removal of this pollutant with this pyrene grafted onto zinc oxide nanoparticles proceeded via pseudo-first order (R2 equals 0.931) and Langmuir isotherm models (R2 equals 0.980) respectively. These results indicated that this material could serve as alternate material to already established materials for the removal of recalcitrant organic pollutants from aqueous solutions. Moreover, the adsorbent also showed reusability potential for this contaminant. Similarly, the adsorbent showed high removal efficiency and capacity in all batch adsorption experiments for brilliant green (BG) adsorption. The highest adsorption efficiency of 88.8 percent was accomplished with 79.8 mg at pH 6.50 and temperature of 20 equals 2oC within 360 minutes. BG adsorption rate mechanism was best explained by the pseudo-first order kinetic model (R2 equals 0.903). Dye adsorption behaviour was best explained using Langmuir isotherm (R2 equals 0.980). Reusability of the adsorbent showed that the adsorbent is efficient after three runs. The overall results of adsorption by a way of comparison of the adsorption capacity of this novel material with respect to the contaminants is in this trend: brilliant green greater methyl violet greater simazine. This study indicates that this novel material can serve as new material for the removal of herbicides and dyes as well as vast variety of pollutants from wastewater considering its high adsorption efficiency and its recyclability. Thus, industries can explore the use of this material for the removal of varying pollutants from wastewater. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Samuel, Zipho
- Date: 2022-03
- Subjects: Land treatment of wastewater , Zinc oxide , Water pollution control industry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27754 , vital:69407
- Description: Drinking water scarcity is a global crisis even though water covers about three quarters of the earth. One of the major causes of this scarcity is water pollution, which is a result of human activities. This has been noticed and reported for a number of years but is still unsolved and intensifying. Hence, scientists are busy trying to find solutions to this global menace. In this study, zinc oxide nanoparticles were synthesised via co-precipitation, a cost reasonable method and functionalized by grafting a pyrene ligand on its surface in order to provide a scaffold to which many other functionalities can be adsorbed. By so doing, the efficiency and capacity of bare nanoparticles is improved. The synthesised pyrene ligand was successfully characterised with nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscope (FTIR). The adsorbent was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, energy dispersive x-ray (EDX) and thermogravimetric analyzer (TGA). The choice of zinc oxide nanoparticles as preferred adsorbent was due to their exceptional properties including large surface area, thermal and chemical stabilities. These properties are the reason zinc oxide nanoparticles possess high adsorption efficiency and capacity. The results of characterization indicated a decreased particle size and improved thermal stabilities of the pyrene grafted zinc oxide nanoparticles compared to the zinc oxide nanoparticles, showing that this material can be employed even at higher temperatures. The average particle size of the bare nanoparticles decreased from 290 to 181 nm after functionalization. Thermal stability increased from 550oC in the bare nanoparticles to 650oC in the functionalized nanoparticles. Characteristic reflections of zinc oxide nanoparticles in the XRD analysis were maintained even after functionalization However, diffractogram roughness was noticed for the functionalized nanoparticles due to the introduction of the amorphous layer from the ligand. This novel material was employed for the removal of an herbicide, simazine as well as two dyes, methyl violet and brilliant green from aqueous solutions by batch adsorption experiments. The kinetics and isotherm studies of the different adsorption processes were carried out by using three of the commonly used kinetic and isotherm models (pseudo-first order, intraparticle diffusion and pseudo-second order) and (Langmuir, Temkin isotherms and Freundlich) respectively. From all batch adsorption experiments conducted for simazine removal, the adsorbent showed effectiveness and high adsorption capacity for the removal of simazine. The highest observed efficiency and capacity were 71.3 percent and 137 mg/g respectively at pH equals 2, time equals 60 minutes, adsorbent dose equals 20 mg and adsorbate conc equals 0. 281 mg/L. Kinetics study for the adsorption of simazine favoured pseudo-first order. However, Langmuir isotherm could also be applicable to understand the adsorption process. The material also showed reusability potential of up to three cycles for this contaminant indicating that this material can be re-used. In the case of the removal of methyl violet from aqueous solution, the adsorbent showed a reasonable adsorption maximum capacity (qmax) (31.5 mg/g) at contact time equals 360 min, adsorbent dose approximately equals 40 mg, temperature equals 20 plus 2oC and pH equals 6.5, when compared to other adsorbents previously reported for the removal of methyl violet (MV) in literature. Kinetics and isotherm studies indicated that the process for the removal of this pollutant with this pyrene grafted onto zinc oxide nanoparticles proceeded via pseudo-first order (R2 equals 0.931) and Langmuir isotherm models (R2 equals 0.980) respectively. These results indicated that this material could serve as alternate material to already established materials for the removal of recalcitrant organic pollutants from aqueous solutions. Moreover, the adsorbent also showed reusability potential for this contaminant. Similarly, the adsorbent showed high removal efficiency and capacity in all batch adsorption experiments for brilliant green (BG) adsorption. The highest adsorption efficiency of 88.8 percent was accomplished with 79.8 mg at pH 6.50 and temperature of 20 equals 2oC within 360 minutes. BG adsorption rate mechanism was best explained by the pseudo-first order kinetic model (R2 equals 0.903). Dye adsorption behaviour was best explained using Langmuir isotherm (R2 equals 0.980). Reusability of the adsorbent showed that the adsorbent is efficient after three runs. The overall results of adsorption by a way of comparison of the adsorption capacity of this novel material with respect to the contaminants is in this trend: brilliant green greater methyl violet greater simazine. This study indicates that this novel material can serve as new material for the removal of herbicides and dyes as well as vast variety of pollutants from wastewater considering its high adsorption efficiency and its recyclability. Thus, industries can explore the use of this material for the removal of varying pollutants from wastewater. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
Threatened plant species in Vhembe Biosphere Reserve, Limpopo province, South Africa: Problems and prospects of conservation and utilization
- Ramarumo, Luambo Jeffrey https://orcid.org/0000-0002-2393-6982
- Authors: Ramarumo, Luambo Jeffrey https://orcid.org/0000-0002-2393-6982
- Date: 2022-03
- Subjects: Plants -- Extinction , Rare plants , Botany, Economic
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22754 , vital:52738
- Description: Threatened plant species are those species that are vulnerable or at the risk of extinction. According to Version 3.1 of the International Union for Conservation of Nature (IUCN)’s Red List Categories and Criteria, the three categories of threat in order of increasing risk of extinction are: Vulnerable (VU), Endangered (EN) and Critically Endangered (CR). These species are oftenly protected by both national and international obligations. Scientific evidence suggests that threatened plants are disappearing at an alarming rate. The current expansion of agricultural land, urbanization, over-exploitation of biological resources, climate change and invasive alien species are regarded as major drivers of biodiversity loss and high rate of species extinction worldwide. Scientists and conservation managers are seeking to understand and monitor plant species that are likely to be on the verge of extinction. Monitoring of threatened plants can be better achieved through insights about indigenous knowledge dynamics associated with such species. Scientific scholars including botanists, ethnobotanists, conservationists and anthropologists, all share common interest about the use of indigenous knowledge for livelihoods, scientific and economic growth. As a result, there is a growing interest on indigenous knowledge researches, particularly involving utilization and conservation of plant species. Given the fact that recent scientific evidence suggests that such studies are lacking in South African Biosphere Reserves, as well as the fact that scientist and conservation managers are seeking to understand species likely to be on the verge of extinction risk. It is within this context that this study is aimed at investigating threatened plant species utilization, conservation statuses and distribution in the Vhembe Biosphere Reserve, Limpopo Province in South Africa. The hypothesis of this study states that traditional knowledge about utilization, distribution and conservation statuses of threatened plant species provide suggestions for appropriate conservation practices. Since the current study is ethnobotanical in nature that is focusing on human interactions with plants, the research methods used addressed multidisciplinary aspects and involved disciplinary integration. An integrated participatory research approach focusing on shared learning, forging collaborative relations with participants, analyzing and validating the shared knowledge was used to document ethnobotanical data within the study area. This research approach was selected as it is considered to be a quick and effective way of acquiring data associated with indigenous knowledge systems. To offset the elements of bias during data collection, the research technique was designed to accommodate core principles that interlinked participatory rural appraisal (PRA) and rapid rural appraisal (RRA). Furthermore, the integrated core principles of participatory rural appraisal and rapid rural appraisal were used with conventional methods such as field surveys and interviews using questionnaires. Therefore, ethnobotanical data were collected through interviews with 203 participants. The data associated with threatened plant’s population size were gathered through literal counting of individual plants as per the IUCN’s Red List Criteria. Data associated with the conservation statuses were gathered from both the South African National Biodiversity Institute and IUCN databases. A total of 13 useful threatened plants belonging to 12 families were recorded with their conservation statuses ranging from being Vulnerable to Critically Endangered. The majority of the threatened plant species (46.0percent) were used for medicinal purposes only, followed by species used for medicinal purposes and as ornamentals (23.0percent). The frequently cited useful threatened species with use values (UV) > 0.024, relative frequency citation (RFC) > 0.059 and fidelity level percentage (FLpercent) > 5.911percent, included Asparagus sekukuniensis, Bowiea volubilis, Brackenridgea zanguebarica, Ocotea bullata, Rhynchosia vendae, Siphonochilus aethiopicus and Warburgia salutaris. About 47.0percent of the recorded useful threatened plants were distributed in remote areas of the Thathe Vonḓo and its surroundings. Threatened plants with population size < 100 adult individuals constituted the majority (61.54percent). Birdlime-making plant species were also documented in the current study. A total of 12 birdlime-making plants belonging to six families were recorded, including threatened Huernia nouhuysii, which is categorized as Vulnerable in South Africa. Amongst the recorded families, Loranthaceae and Euphorbiaceae were categorized as the most frequently utilized families. Among the recorded species, six of them were reported to being used in the birdlime-making for the first time and these species include Euphorbia pulvinata (17.2percent), followed by Tapinanthus forbesii (8percent), Tapinanthus rubromarginatus (7.2percent), Erianthemum ngamicum (7.2percent), Englerophytum magalismon-tanum (3.6percent), Huernia nouhuysii (2.0percent), and Euphorbia tirucalli (0.8percent). Only three plant parts were utilized for birdlime-making. The milky latex was preferred plant part (58.3percent), followed by fruit (33.3percent) and root bark (8.4percent). Birdlime-making techniques involved crushing, which accounted for 55.7percent, followed by air blown (29.6percent) and boiling (14.7percent). Furthermore, the complementary contribution of birdlime toward human development included, being used for bird hunting or trapping small birds (45.8percent), adhesion (23.2percent), teeth cleaning (17.2percent) and roof-waterproofing (13.8percent). The indigenous conservation strategies employed by participants included harvesting of single lateral root per individual medicinal plant (15.3percent), medicinal and timber materials are only harvested during winter season (16.7percent), the use of moist soil to cover injured plant part after bark harvest (18.2percent), prohibit harvesting of and/ or from an injured plant (11.8percent), collection of dried or fallen plants for firewood (8.4percent), issuing of permits by traditional council through the chief or headman to allow collection of medicinal materials and timber (9.9percent), prohibit chopping down of medicinal plant species (13.8percent) and collection of some Critically Endangered plant species such as Brackenridgea zanguebarica and Siphonochilus aethiopicus during the night by authorized people only (5.9percent). The hypothesis which stated that traditional knowledge about utilization, distribution and conservation statuses of threatened plant species provide suggestions for appropriate conservation practices can therefore, not be rejected as there is room for further and more detailed ethnobotanical investigations that is focused on human interactions with threatened plant species. The data presented in this thesis could be used as baseline information for formulating new conservation strategies, monitoring and management plans of threatened plant species not only in the Vhembe Biosphere Reserve, but in other regions of South African. This study provided insights associated with ethnomedicinal uses of Asparagus sekukuniensis, Protea laetans and Encephalartos hirsutus. Results of this study could also stimulate interest in other scientific disciplines such as the phytochemistry, pharmacology, bioprocessing, conservation and anthropology involving documentation threatened plant species. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
- Authors: Ramarumo, Luambo Jeffrey https://orcid.org/0000-0002-2393-6982
- Date: 2022-03
- Subjects: Plants -- Extinction , Rare plants , Botany, Economic
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22754 , vital:52738
- Description: Threatened plant species are those species that are vulnerable or at the risk of extinction. According to Version 3.1 of the International Union for Conservation of Nature (IUCN)’s Red List Categories and Criteria, the three categories of threat in order of increasing risk of extinction are: Vulnerable (VU), Endangered (EN) and Critically Endangered (CR). These species are oftenly protected by both national and international obligations. Scientific evidence suggests that threatened plants are disappearing at an alarming rate. The current expansion of agricultural land, urbanization, over-exploitation of biological resources, climate change and invasive alien species are regarded as major drivers of biodiversity loss and high rate of species extinction worldwide. Scientists and conservation managers are seeking to understand and monitor plant species that are likely to be on the verge of extinction. Monitoring of threatened plants can be better achieved through insights about indigenous knowledge dynamics associated with such species. Scientific scholars including botanists, ethnobotanists, conservationists and anthropologists, all share common interest about the use of indigenous knowledge for livelihoods, scientific and economic growth. As a result, there is a growing interest on indigenous knowledge researches, particularly involving utilization and conservation of plant species. Given the fact that recent scientific evidence suggests that such studies are lacking in South African Biosphere Reserves, as well as the fact that scientist and conservation managers are seeking to understand species likely to be on the verge of extinction risk. It is within this context that this study is aimed at investigating threatened plant species utilization, conservation statuses and distribution in the Vhembe Biosphere Reserve, Limpopo Province in South Africa. The hypothesis of this study states that traditional knowledge about utilization, distribution and conservation statuses of threatened plant species provide suggestions for appropriate conservation practices. Since the current study is ethnobotanical in nature that is focusing on human interactions with plants, the research methods used addressed multidisciplinary aspects and involved disciplinary integration. An integrated participatory research approach focusing on shared learning, forging collaborative relations with participants, analyzing and validating the shared knowledge was used to document ethnobotanical data within the study area. This research approach was selected as it is considered to be a quick and effective way of acquiring data associated with indigenous knowledge systems. To offset the elements of bias during data collection, the research technique was designed to accommodate core principles that interlinked participatory rural appraisal (PRA) and rapid rural appraisal (RRA). Furthermore, the integrated core principles of participatory rural appraisal and rapid rural appraisal were used with conventional methods such as field surveys and interviews using questionnaires. Therefore, ethnobotanical data were collected through interviews with 203 participants. The data associated with threatened plant’s population size were gathered through literal counting of individual plants as per the IUCN’s Red List Criteria. Data associated with the conservation statuses were gathered from both the South African National Biodiversity Institute and IUCN databases. A total of 13 useful threatened plants belonging to 12 families were recorded with their conservation statuses ranging from being Vulnerable to Critically Endangered. The majority of the threatened plant species (46.0percent) were used for medicinal purposes only, followed by species used for medicinal purposes and as ornamentals (23.0percent). The frequently cited useful threatened species with use values (UV) > 0.024, relative frequency citation (RFC) > 0.059 and fidelity level percentage (FLpercent) > 5.911percent, included Asparagus sekukuniensis, Bowiea volubilis, Brackenridgea zanguebarica, Ocotea bullata, Rhynchosia vendae, Siphonochilus aethiopicus and Warburgia salutaris. About 47.0percent of the recorded useful threatened plants were distributed in remote areas of the Thathe Vonḓo and its surroundings. Threatened plants with population size < 100 adult individuals constituted the majority (61.54percent). Birdlime-making plant species were also documented in the current study. A total of 12 birdlime-making plants belonging to six families were recorded, including threatened Huernia nouhuysii, which is categorized as Vulnerable in South Africa. Amongst the recorded families, Loranthaceae and Euphorbiaceae were categorized as the most frequently utilized families. Among the recorded species, six of them were reported to being used in the birdlime-making for the first time and these species include Euphorbia pulvinata (17.2percent), followed by Tapinanthus forbesii (8percent), Tapinanthus rubromarginatus (7.2percent), Erianthemum ngamicum (7.2percent), Englerophytum magalismon-tanum (3.6percent), Huernia nouhuysii (2.0percent), and Euphorbia tirucalli (0.8percent). Only three plant parts were utilized for birdlime-making. The milky latex was preferred plant part (58.3percent), followed by fruit (33.3percent) and root bark (8.4percent). Birdlime-making techniques involved crushing, which accounted for 55.7percent, followed by air blown (29.6percent) and boiling (14.7percent). Furthermore, the complementary contribution of birdlime toward human development included, being used for bird hunting or trapping small birds (45.8percent), adhesion (23.2percent), teeth cleaning (17.2percent) and roof-waterproofing (13.8percent). The indigenous conservation strategies employed by participants included harvesting of single lateral root per individual medicinal plant (15.3percent), medicinal and timber materials are only harvested during winter season (16.7percent), the use of moist soil to cover injured plant part after bark harvest (18.2percent), prohibit harvesting of and/ or from an injured plant (11.8percent), collection of dried or fallen plants for firewood (8.4percent), issuing of permits by traditional council through the chief or headman to allow collection of medicinal materials and timber (9.9percent), prohibit chopping down of medicinal plant species (13.8percent) and collection of some Critically Endangered plant species such as Brackenridgea zanguebarica and Siphonochilus aethiopicus during the night by authorized people only (5.9percent). The hypothesis which stated that traditional knowledge about utilization, distribution and conservation statuses of threatened plant species provide suggestions for appropriate conservation practices can therefore, not be rejected as there is room for further and more detailed ethnobotanical investigations that is focused on human interactions with threatened plant species. The data presented in this thesis could be used as baseline information for formulating new conservation strategies, monitoring and management plans of threatened plant species not only in the Vhembe Biosphere Reserve, but in other regions of South African. This study provided insights associated with ethnomedicinal uses of Asparagus sekukuniensis, Protea laetans and Encephalartos hirsutus. Results of this study could also stimulate interest in other scientific disciplines such as the phytochemistry, pharmacology, bioprocessing, conservation and anthropology involving documentation threatened plant species. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-03
A framework for communicating climate information to rural small-scale farmers in the Eastern Cape Province, South Africa using systems thinking approach
- Pindura, Tineyi Herbert https://orcid.org/0000-0001-7233-6222
- Authors: Pindura, Tineyi Herbert https://orcid.org/0000-0001-7233-6222
- Date: 2022-02
- Subjects: Farms, Small , Agriculture -- Environmental aspects , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22809 , vital:52784
- Description: In the Eastern Cape of South Africa, rural small-scale farmers live in uncertain times characterized by climate change and variability, which intensify social, political and financial inequalities. Therefore, there is a need to increase the understanding and interpretation of climate information to minimize crop production risk, reduce rural small-scale farmers’ vulnerability to climate, and maximize opportunities. Increasing the resilience among rural small-scale farmers requires appropriate and viable practical approaches. By using systems thinking approach (and the Raymond Mhlaba Municipality in the Eastern Cape as a study area), this research disseminates the complex nature of current climate information frameworks. Through inputs from farmers (through a Farmers Research Group methodology) and climate data, this thesis developed a new framework for communicating climate information (herein referred as the climate information communication systems framework) to rural small-scale farmers. The proposed climate information communication systems framework successfully integrates scientific and traditional knowledge. The framework constitutes certain stages, where the farming system and crop identification is the first stage. The second stage is the requirements stage, which has two relationships: scientist to crop requirements and farmers to crop requirements. At the scientist to crop requirements level, users will examine crop requirements by combining climatic data and crop simulations, while at the farmers to crop requirement, rural small-scale farmers use the scientific information to plan for the farming season. The farmer then decides the planting and growing period as well as the harvest timing. The study suggests that building links between rural small-scale farmers, extension officers, and scientists makes sharing information easier. The proposed climate information framework design illustrates that stakeholders now have a personal relationship with climate information transmission and can influence the different actions to reduce the effect of climate change unpredictability. The study established that climate change and variability influence recent agricultural output trends. Recent temperature and rainfall trends could have resulted in low crop productivity in the study area. The study also reflected that women are a critical resource in agriculture and rural economy and that middle-aged men and youth are less interested in farming. The findings also showed that women are more receptive to climate information; hence, to promote access and use of climate information remains vital to consider gender-specific aspects for appropriate decision-making in the agriculture sector. The study also recommends enhancing the Farmers Research Group technique. In the past, the scope of this methodology has been narrowly focused, and it must be explored to incorporate additional types of climate information and more debate about how climate is related to the decisions farmers for implementation or consideration. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-02
- Authors: Pindura, Tineyi Herbert https://orcid.org/0000-0001-7233-6222
- Date: 2022-02
- Subjects: Farms, Small , Agriculture -- Environmental aspects , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22809 , vital:52784
- Description: In the Eastern Cape of South Africa, rural small-scale farmers live in uncertain times characterized by climate change and variability, which intensify social, political and financial inequalities. Therefore, there is a need to increase the understanding and interpretation of climate information to minimize crop production risk, reduce rural small-scale farmers’ vulnerability to climate, and maximize opportunities. Increasing the resilience among rural small-scale farmers requires appropriate and viable practical approaches. By using systems thinking approach (and the Raymond Mhlaba Municipality in the Eastern Cape as a study area), this research disseminates the complex nature of current climate information frameworks. Through inputs from farmers (through a Farmers Research Group methodology) and climate data, this thesis developed a new framework for communicating climate information (herein referred as the climate information communication systems framework) to rural small-scale farmers. The proposed climate information communication systems framework successfully integrates scientific and traditional knowledge. The framework constitutes certain stages, where the farming system and crop identification is the first stage. The second stage is the requirements stage, which has two relationships: scientist to crop requirements and farmers to crop requirements. At the scientist to crop requirements level, users will examine crop requirements by combining climatic data and crop simulations, while at the farmers to crop requirement, rural small-scale farmers use the scientific information to plan for the farming season. The farmer then decides the planting and growing period as well as the harvest timing. The study suggests that building links between rural small-scale farmers, extension officers, and scientists makes sharing information easier. The proposed climate information framework design illustrates that stakeholders now have a personal relationship with climate information transmission and can influence the different actions to reduce the effect of climate change unpredictability. The study established that climate change and variability influence recent agricultural output trends. Recent temperature and rainfall trends could have resulted in low crop productivity in the study area. The study also reflected that women are a critical resource in agriculture and rural economy and that middle-aged men and youth are less interested in farming. The findings also showed that women are more receptive to climate information; hence, to promote access and use of climate information remains vital to consider gender-specific aspects for appropriate decision-making in the agriculture sector. The study also recommends enhancing the Farmers Research Group technique. In the past, the scope of this methodology has been narrowly focused, and it must be explored to incorporate additional types of climate information and more debate about how climate is related to the decisions farmers for implementation or consideration. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-02
Adsorption of antibiotic-resistant bacteria and their cell-free deoxyribonucleic acid harbouring resistance genes in drinking water with metal oxides
- Authors: Tobechukwu, Anthony Eric
- Date: 2022
- Subjects: Metallic oxides , DNA -- Synthesis , Drinking water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27787 , vital:69494
- Description: Access to cleaner water is essential to human health. The incidence of Antibiotic Resistant Bacteria ARB in drinking water and subsequent proliferation of Antibiotic Resistance Genes ARGs in drinking water is a concern for public health. The free DNA cassette harboring antibiotic resistance gene in drinking water has been linked with impaired public health. The ARGs allows bacteria to develop resistance towards antibiotics while ARB render antibiotics ineffective. Existing drinking water treatment technologies eg adsorption, ozonation and chlorination, have shown different levels of potency in the removal of conventional water pollutant. These technologies, which operating principles is based on oxidation or mass transfer, have been explored to gained an insight into their efficiency in the removal of ARB ARGs in water treatment. In general, methods that functions by mass transfer of the ARB ARGs is more effectively than bacteria oxidation. Consequently, adsorption technology was chosen using common metal oxide adsorbents. The adsorbents ZnOAg CeO2 and Al2O3 were synthesized via the self propagation combustion method. This method was selected because of the purity of the final product and the energy requirement. One of the challenges in the removal of ARB in drinking water is the release of ARGs. To address this concern, five different ZnOAg heterostructures were synthesized for the removal of Enterococci faecium. ZnOAg was chosen because of the bactericidal and bacteriostatic characteristics. The study revealed that the concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity q34.11 CFUg was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudofirst-order kinetic equation and adsorbents Ag2Zn1 Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation 6.5 – 8.5 whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDREF onto the different heterostructure. Interestingly the MDREF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal. Cerium IV oxide CeO2 was selected because of high adsorption towards phosphate, backbone base for DNA. To prevent the problem of antibiotic resistance, we have synthesized a CeO2 adsorbent that exhibit highly positive character in a wide pH range, via the simple self-propagation combustion protocol, for the removal of free DNA harboring antibiotic resistance genes. Molecular characterization of the extracted genes showed that the sizes for E. coli and inherent gyrB genes are 147 and 460 bp with a purity between 19 2.0. The XRD SEM TEM, and PZC results of the as-synthesized CeO2 showed an agglomerate of pure cubic-faced centered material and highly crystalline, with a net charge at pH 6.2. Experimental results revealed that the reaction proceeded via pseudo first-order kinetic, and it is governed by electrostatic attraction. The free- DNA solution pH electrolyte, and competing ions impacted on the adsorption process. Further experimental results showed that the as-synthesized CeO2 adsorbent has the potential to be used for the removal of free DNA harboring ARGs from tap-water even under oxic conditions. Alumina Al2O3 is an abundant adsorbent that has also shown high removal capacity towards phosphate. The highly pure synthesized Al2O3 adsorbent exhibit fluid-like behaviour under Scanning Electron Microscope SEM. The XRD pattern corresponds to αAl2O3. The adsorption kinetics was described by pseudo second orderadsorption capacity 11.7 μgg implying chemisorption, which agrees with the electrostatic force of attraction caused by opposing ions. This result was evident by the effect of different ions in the tap water. The synthesized α-Al2O3 has the potential for the removal of cell free DNA harbouring multiply resistant genes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Tobechukwu, Anthony Eric
- Date: 2022
- Subjects: Metallic oxides , DNA -- Synthesis , Drinking water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27787 , vital:69494
- Description: Access to cleaner water is essential to human health. The incidence of Antibiotic Resistant Bacteria ARB in drinking water and subsequent proliferation of Antibiotic Resistance Genes ARGs in drinking water is a concern for public health. The free DNA cassette harboring antibiotic resistance gene in drinking water has been linked with impaired public health. The ARGs allows bacteria to develop resistance towards antibiotics while ARB render antibiotics ineffective. Existing drinking water treatment technologies eg adsorption, ozonation and chlorination, have shown different levels of potency in the removal of conventional water pollutant. These technologies, which operating principles is based on oxidation or mass transfer, have been explored to gained an insight into their efficiency in the removal of ARB ARGs in water treatment. In general, methods that functions by mass transfer of the ARB ARGs is more effectively than bacteria oxidation. Consequently, adsorption technology was chosen using common metal oxide adsorbents. The adsorbents ZnOAg CeO2 and Al2O3 were synthesized via the self propagation combustion method. This method was selected because of the purity of the final product and the energy requirement. One of the challenges in the removal of ARB in drinking water is the release of ARGs. To address this concern, five different ZnOAg heterostructures were synthesized for the removal of Enterococci faecium. ZnOAg was chosen because of the bactericidal and bacteriostatic characteristics. The study revealed that the concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity q34.11 CFUg was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudofirst-order kinetic equation and adsorbents Ag2Zn1 Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation 6.5 – 8.5 whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDREF onto the different heterostructure. Interestingly the MDREF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal. Cerium IV oxide CeO2 was selected because of high adsorption towards phosphate, backbone base for DNA. To prevent the problem of antibiotic resistance, we have synthesized a CeO2 adsorbent that exhibit highly positive character in a wide pH range, via the simple self-propagation combustion protocol, for the removal of free DNA harboring antibiotic resistance genes. Molecular characterization of the extracted genes showed that the sizes for E. coli and inherent gyrB genes are 147 and 460 bp with a purity between 19 2.0. The XRD SEM TEM, and PZC results of the as-synthesized CeO2 showed an agglomerate of pure cubic-faced centered material and highly crystalline, with a net charge at pH 6.2. Experimental results revealed that the reaction proceeded via pseudo first-order kinetic, and it is governed by electrostatic attraction. The free- DNA solution pH electrolyte, and competing ions impacted on the adsorption process. Further experimental results showed that the as-synthesized CeO2 adsorbent has the potential to be used for the removal of free DNA harboring ARGs from tap-water even under oxic conditions. Alumina Al2O3 is an abundant adsorbent that has also shown high removal capacity towards phosphate. The highly pure synthesized Al2O3 adsorbent exhibit fluid-like behaviour under Scanning Electron Microscope SEM. The XRD pattern corresponds to αAl2O3. The adsorption kinetics was described by pseudo second orderadsorption capacity 11.7 μgg implying chemisorption, which agrees with the electrostatic force of attraction caused by opposing ions. This result was evident by the effect of different ions in the tap water. The synthesized α-Al2O3 has the potential for the removal of cell free DNA harbouring multiply resistant genes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Development and in vitro biological studies of polymer-based wound dressings with a high haemostatic ability for the management of wounds
- Nqoro, Xhamla https://orcid.org/0000-0002-2065-3629
- Authors: Nqoro, Xhamla https://orcid.org/0000-0002-2065-3629
- Date: 2022
- Subjects: Wound healing , Surgical wound infections , Wound treatment equipment industry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27970 , vital:71404
- Description: Wounds are usually accompanied by complications such as excessive bleeding and bacteria invasion. The design of wound dressings that rapidly stop excessive bleeding and inhibit bacterial invasion is crucial to promoting accelerated wound healing. To meet the abovementioned requirements in wound dressings, topical gels were prepared from sodium alginate SA and carboxymethylcellulose CMC. The wound dressings were loaded with an antifibrinolytic agent, tranexamic acid TA, essential oils, and a variety of metal-based nanoparticles, and carbon-based biomaterials. The scanning electron microscopy SEM and X-ray diffraction XRD confirmed the successful formation of the nanoparticles. The prepared formulations exhibited in vitro drug release kinetics that best fitted with the Korsmeyer-Peppas model. These gels exhibited good spreadability and viscosity, showing a shear-thinning behaviour with pH between 6.7 and 7.3, signifying suitability for skin application and ease of application. The prepared topical gels exhibited significant antibacterial effects against gram-negative and gram-positive strains of bacteria. SA EO-based formulations showed high antibacterial activity across all bacterial strains, followed by SA-based formulations compared to CMC-based formulations, which exhibited moderate antibacterial activity. Moreover, the prepared gels showed good cytocompatibility, promoted cell proliferation, and exhibited 80 percent wound closure on day 3 compared to the untreated group, which showed a 38 percent wound reduction in vitro. Excellent blood clotting properties were observed with CMC-based gels compared to other formulations. However, all the prepared formulations exhibited outstanding blood clotting ability compared to the control, showing that they can promote rapid blood coagulation. The features presented by the prepared gels reveal that they are suitable for rapid wound healing , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Nqoro, Xhamla https://orcid.org/0000-0002-2065-3629
- Date: 2022
- Subjects: Wound healing , Surgical wound infections , Wound treatment equipment industry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27970 , vital:71404
- Description: Wounds are usually accompanied by complications such as excessive bleeding and bacteria invasion. The design of wound dressings that rapidly stop excessive bleeding and inhibit bacterial invasion is crucial to promoting accelerated wound healing. To meet the abovementioned requirements in wound dressings, topical gels were prepared from sodium alginate SA and carboxymethylcellulose CMC. The wound dressings were loaded with an antifibrinolytic agent, tranexamic acid TA, essential oils, and a variety of metal-based nanoparticles, and carbon-based biomaterials. The scanning electron microscopy SEM and X-ray diffraction XRD confirmed the successful formation of the nanoparticles. The prepared formulations exhibited in vitro drug release kinetics that best fitted with the Korsmeyer-Peppas model. These gels exhibited good spreadability and viscosity, showing a shear-thinning behaviour with pH between 6.7 and 7.3, signifying suitability for skin application and ease of application. The prepared topical gels exhibited significant antibacterial effects against gram-negative and gram-positive strains of bacteria. SA EO-based formulations showed high antibacterial activity across all bacterial strains, followed by SA-based formulations compared to CMC-based formulations, which exhibited moderate antibacterial activity. Moreover, the prepared gels showed good cytocompatibility, promoted cell proliferation, and exhibited 80 percent wound closure on day 3 compared to the untreated group, which showed a 38 percent wound reduction in vitro. Excellent blood clotting properties were observed with CMC-based gels compared to other formulations. However, all the prepared formulations exhibited outstanding blood clotting ability compared to the control, showing that they can promote rapid blood coagulation. The features presented by the prepared gels reveal that they are suitable for rapid wound healing , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Evaluation of functionalized silver and silica nanoparticles for the removal of deoxyribonucleic acid conveying antibiotics resistance genes from water
- Authors: Ezeuko, Adaora Stella
- Date: 2022
- Subjects: DNA , Silica , Water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27765 , vital:69414
- Description: Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Ezeuko, Adaora Stella
- Date: 2022
- Subjects: DNA , Silica , Water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27765 , vital:69414
- Description: Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
In Silico analysis of Spermidine, Spermine and Putrescine interaction with selected heat shock proteins from Plasmodium falciparum 3D7 towards malaria drug development
- Authors: Godlo, Sesethu
- Date: 2022
- Subjects: Heat shock proteins , Malaria vaccine , Plasmodium falciparum
- Language: English
- Type: Master'stheses , text
- Identifier: http://hdl.handle.net/10353/27709 , vital:69395
- Description: Malaria is a mosquito-borne disease that affects around half of the world's population. It is one of the most common parasite infections that endangers human life. One of the most serious issues in malaria therapy is the emergence and spread of antimalarial drug-resistant Plasmodium parasites. This is due to the Plasmodium parasite's constant evolution and development of new methods of surviving medication toxicity. Studies of antimalarial drug development have been focused on polyamine biosynthesis by targeting precursors such as ornithine decarboxylase, adenosylmethionine decarboxylase, and spermidine synthase and protein-protein interactions between Plasmodium falciparum chaperones spotting out Hsp90, Hsp70, and Hsp40 as potential targets with little attention being paid to the interaction between polyamines and molecular chaperones. Therefore, this study seeks to identify interactions between polyamines and molecular chaperones present in the malarial parasite Plasmodium falciparum 3D7. The identification of these interactions might lead to the design of effective drugs to treat and eliminate malaria. Using computational analysis, this study aims to find interactions between polyamines and molecular chaperones found in the malarial parasite Plasmodium falciparum 3D7. The sequences of the selected heat proteins retrieved, and the 3D structures predicted and validated. These structures were docked with polyamines retrieved from PubChem and MD simulations on the docked interactions were performed. Docking revealed common amino acid residues with hydrogen bonds and salt bridges between all receptors and ligands, with glutamine and aspartic acid standing out. MD simulations revealed that when HSP20 and HSP40 transport the ligands, they pop up or are released too quickly. However, HSP60, HSP70, and HSP90 provide optimism since the ligands remain attached to the proteins for a specific amount of time. To further understand and confirm these interactions wet laboratory studies may be carried out in future. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Godlo, Sesethu
- Date: 2022
- Subjects: Heat shock proteins , Malaria vaccine , Plasmodium falciparum
- Language: English
- Type: Master'stheses , text
- Identifier: http://hdl.handle.net/10353/27709 , vital:69395
- Description: Malaria is a mosquito-borne disease that affects around half of the world's population. It is one of the most common parasite infections that endangers human life. One of the most serious issues in malaria therapy is the emergence and spread of antimalarial drug-resistant Plasmodium parasites. This is due to the Plasmodium parasite's constant evolution and development of new methods of surviving medication toxicity. Studies of antimalarial drug development have been focused on polyamine biosynthesis by targeting precursors such as ornithine decarboxylase, adenosylmethionine decarboxylase, and spermidine synthase and protein-protein interactions between Plasmodium falciparum chaperones spotting out Hsp90, Hsp70, and Hsp40 as potential targets with little attention being paid to the interaction between polyamines and molecular chaperones. Therefore, this study seeks to identify interactions between polyamines and molecular chaperones present in the malarial parasite Plasmodium falciparum 3D7. The identification of these interactions might lead to the design of effective drugs to treat and eliminate malaria. Using computational analysis, this study aims to find interactions between polyamines and molecular chaperones found in the malarial parasite Plasmodium falciparum 3D7. The sequences of the selected heat proteins retrieved, and the 3D structures predicted and validated. These structures were docked with polyamines retrieved from PubChem and MD simulations on the docked interactions were performed. Docking revealed common amino acid residues with hydrogen bonds and salt bridges between all receptors and ligands, with glutamine and aspartic acid standing out. MD simulations revealed that when HSP20 and HSP40 transport the ligands, they pop up or are released too quickly. However, HSP60, HSP70, and HSP90 provide optimism since the ligands remain attached to the proteins for a specific amount of time. To further understand and confirm these interactions wet laboratory studies may be carried out in future. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Preparation, characterization, and in vitro evaluation of polymer-based wound dressings for the management of chronic wounds
- Authors: Alven, Sibusiso
- Date: 2022
- Subjects: Toxicity testing -- In vitro , Wound healing , Chronic diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27992 , vital:71414
- Description: Microbial infections are responsible for the retarded recovery process of chronic wounds. Polymer-based scaffolds possess features suitable for the treatment of chronic injuries. However, these scaffolds are commonly encapsulated with therapeutic agents to enhance their biological activities, including antibacterial efficacy. In this research, two types of polymer-based scaffolds were formulated and evaluated as effective formulations for the treatment of chronic wounds: sponges and topical gels. Sponges were formulated from cross-linking of gelatin and PEG. Ag nanoparticles and metronidazole were incorporated into the sponges to improve their antibacterial activity. Topical gels were loaded with essential oils and Ag nanoparticles and prepared from CMC and poloxamer. The prepared sponges and topical gels were evaluated using various analysis and characterization techniques. SEM/EDX, FTIR, and TGA were employed to characterize gelatin/PEG hybrid sponges followed by porosity, in vitro biodegradability, cytotoxicity, and antibacterial studies. FTIR, SEM/EDX, and TGA confirmed their physicochemical properties and successful fabrication of sponges loaded with metronidazole and Ag nanoparticles. The sponges were biodegradable, indicating their capability to induce skin regeneration. The drug release studies showed a rapid release of metronidazole 28.32-71.97 percent from the sponges over the first hour, followed by a sustained drug release. The Ag nanoparticles were released in a sustained manner, suggesting that these sponges can rapidly destroy bacteria and inhibit persisting bacterial infections as well as protect the lesion bed from further bacteria infections. The in vitro antibacterial studies of sponges displayed superior antibacterial activity against most of the Gram-negative and Gram-positive bacteria strains commonly found in chronic wound infections with a MIC value of 15.625 μg/mL. In vitro cytotoxicity experiments revealed excellent biocompatibility with a percent cell viability of more than 70 percent. The in vitro wound scratch healing assay exhibited that the sponges encapsulated with only metronidazole promoted high cell migration than the dual drug-loaded sponges and untreated cells, suggesting its potential to quicken the wound healing process. CMC/Poloxamer topical gels were also characterized by FTIR, followed by pH, viscosity, spreadability, cytotoxicity, and antibacterial studies. FTIR showed successful preparation of CMC/Poloxamer topical gels loaded with essential oils and Ag nanoparticles. The topical gels exhibited pH in the range of 5.20-6.68, spreadability between 5.4 and 5.9 cm, and viscosity ranged from 216 to 1200 cP at 50 rpm and 210–858 cP at 100 rpm. The in vitro drug release studies demonstrated that Ag nanoparticles were released from the topical gels in a sustained manner. Most formulated topical gels demonstrated superior antimicrobial efficacy against Gram-positive and Gram-negative bacteria strains than the blank gel and controls. The cytotoxicity analysis displayed more than 90.83 percent cell viability for the topical gels, revealing excellent biocompatibility. The outcomes revealed that the topical gels enriched with essential oils lavender and tea tree and Ag nanoparticles and sponges incorporated with metronidazole and Ag nanoparticles are potential wound dressing scaffolds that can be employed for the treatment of chronic infected injuries. The in vitro wound healing experiments showed that the HaCaT cells cultured with gels co-enriched with lavender oil and Ag nanoparticles possessed a higher rate of closure in comparison to the untreated cells for 96 hours. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Alven, Sibusiso
- Date: 2022
- Subjects: Toxicity testing -- In vitro , Wound healing , Chronic diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27992 , vital:71414
- Description: Microbial infections are responsible for the retarded recovery process of chronic wounds. Polymer-based scaffolds possess features suitable for the treatment of chronic injuries. However, these scaffolds are commonly encapsulated with therapeutic agents to enhance their biological activities, including antibacterial efficacy. In this research, two types of polymer-based scaffolds were formulated and evaluated as effective formulations for the treatment of chronic wounds: sponges and topical gels. Sponges were formulated from cross-linking of gelatin and PEG. Ag nanoparticles and metronidazole were incorporated into the sponges to improve their antibacterial activity. Topical gels were loaded with essential oils and Ag nanoparticles and prepared from CMC and poloxamer. The prepared sponges and topical gels were evaluated using various analysis and characterization techniques. SEM/EDX, FTIR, and TGA were employed to characterize gelatin/PEG hybrid sponges followed by porosity, in vitro biodegradability, cytotoxicity, and antibacterial studies. FTIR, SEM/EDX, and TGA confirmed their physicochemical properties and successful fabrication of sponges loaded with metronidazole and Ag nanoparticles. The sponges were biodegradable, indicating their capability to induce skin regeneration. The drug release studies showed a rapid release of metronidazole 28.32-71.97 percent from the sponges over the first hour, followed by a sustained drug release. The Ag nanoparticles were released in a sustained manner, suggesting that these sponges can rapidly destroy bacteria and inhibit persisting bacterial infections as well as protect the lesion bed from further bacteria infections. The in vitro antibacterial studies of sponges displayed superior antibacterial activity against most of the Gram-negative and Gram-positive bacteria strains commonly found in chronic wound infections with a MIC value of 15.625 μg/mL. In vitro cytotoxicity experiments revealed excellent biocompatibility with a percent cell viability of more than 70 percent. The in vitro wound scratch healing assay exhibited that the sponges encapsulated with only metronidazole promoted high cell migration than the dual drug-loaded sponges and untreated cells, suggesting its potential to quicken the wound healing process. CMC/Poloxamer topical gels were also characterized by FTIR, followed by pH, viscosity, spreadability, cytotoxicity, and antibacterial studies. FTIR showed successful preparation of CMC/Poloxamer topical gels loaded with essential oils and Ag nanoparticles. The topical gels exhibited pH in the range of 5.20-6.68, spreadability between 5.4 and 5.9 cm, and viscosity ranged from 216 to 1200 cP at 50 rpm and 210–858 cP at 100 rpm. The in vitro drug release studies demonstrated that Ag nanoparticles were released from the topical gels in a sustained manner. Most formulated topical gels demonstrated superior antimicrobial efficacy against Gram-positive and Gram-negative bacteria strains than the blank gel and controls. The cytotoxicity analysis displayed more than 90.83 percent cell viability for the topical gels, revealing excellent biocompatibility. The outcomes revealed that the topical gels enriched with essential oils lavender and tea tree and Ag nanoparticles and sponges incorporated with metronidazole and Ag nanoparticles are potential wound dressing scaffolds that can be employed for the treatment of chronic infected injuries. The in vitro wound healing experiments showed that the HaCaT cells cultured with gels co-enriched with lavender oil and Ag nanoparticles possessed a higher rate of closure in comparison to the untreated cells for 96 hours. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Synthesis and in vitro biological studies of ursolic acid-based hybrid compounds
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Soil erodibility indices affecting the development of gully erosion in highly erodible soils of the Tsitsa Catchment in T35D and T35E, Eastern Cape, South Africa
- Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Authors: Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Date: 2022-01
- Subjects: Soil erosion , River sediments
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22677 , vital:52642
- Description: This study evaluated soil inherent properties for the development of gullies and their erodibility potential using the holistic field and laboratory sample investigation approach. The potential of negative impact of sedimentation on dam and water infrastructure performance has raised the need to evaluate the factors promoting soil erosion leading to land degradation. The study aimed to assess the relationship among the selected properties of soil and variability among various soil groups. A case study design approach was adopted at the T35D and T35E areas of Tsitsa hydrologic Basin, Eastern Cape, South Africa. The task was accomplished through detailed random soil sampling in the field, soil chemical analysis and comparative analysis of soil variables. Based on the scope of the study soil laboratory analysis included the following: particle size distribution, soil textural analysis, physicochemical parameters analysis, macro-and-micronutrient analysis, and micro-porosity analysis. Further spatial and scenario analysis of soil erodibility was done using selected erodibility indices such as Sodium Adsorption Ratio (SAR), Exchangeable Sodium Percentage (ESP), Dispersivity Ratio (DR), Clay Dispersion Ratio (CDR), Clay Flocculation Index (CFI), Water-Stable Aggregate analysis (WSA), and Soil Erodibility factor analysis (KEF). The findings of the study showed that the catchment hosts sixteen distinct soil forms categorized into seven unique soil groups. The results further indicated that the Katspruit soil form of the gleyic soil group has the highest clay-size particles and a considerably high clay dispersion attribute among others soil forms. It was further deduced that gleyic soil type exhibited the highest soil pH (6.36), a considerably low Ca:Mg ratio (1.43), a substantially high sodium ion (0.50 mg/kg), the highest SAR (0.5), lowest WSA (0.018percent) and a substantially high KEF (0.018ab). Similarly, saprolite soils exhibited the nature of the lixisol with a virtually equal amount of clay (43.63percent) and fine sands (41.68percent), the lowest amount of Ca:Mg ratio (1.35), the highest acid saturation (50.59), the highest ESP (8.39), and a considerably high WSA (38.75). Other remarkable problematic soils identified in the study include the lithic soil and the duplex soil. For instance, the Lithic soil is characterized by the highest fine sand-size texture (61.38percent), considerably low organic carbon (2.63percent), low cation exchange capacity (3.55 cmol(+)/kg), much high DR (0.75), very low WSA (0.027percent), and the highest KEF (0.027a). Whereas, the duplex soil is characterized by the highest DR (0.81), critically high CDR (38.19percent), very low WSA (0.019percent), and a considerably high KEF (0.019a). The relatively stable soils within the catchment are the oxidic, and melanic, where the WSA is highest in oxidic (38.19percent) and relatively high for melanic (36.6percent), CFI is highest in melanic (85.02percent), and oxidic (74.32percent), and KEF is relatively low (0.016b) for both. Correlation of the selected soil erodibility indices shows that CFI shares a perfect inverse relationship with CDR while maintaining a strong significant relationship with DR (R = -0.504). Findings also show that the SAR expectedly produced a robust significant relationship with ESP (R = 0.644), while KEF exhibited a solid inverse relationship with WSA (R = 0.913). The correlation across the physical and chemical properties suggests that DR and CDR can be firmly and positively influenced by dispersive clay. At the same time, the two factors maintain a significantly negative relationship with dispersive sand. Also, clay-sized particles depicted a significant relationship with WSA. Physicochemical and chemical parameters influence only the ESP and SAR. A remarkable finding is the influence of iron and its presence on SAR. On the other hand, ESP was distinguished from SAR due to the inverse influence of potassium. The lithic soils identify as members of the collapsible soil of South Africa, while the gleyic soils identify with duplex and saprolite soils in the class of dispersive soils. The vertic soils characterize as expansive soil, while the Duplex soil also exhibits a soft soil attribute. In general, the study suggests that T35D and T35E areas of Tsitsa catchment vary spatially in soil erodibility potential. T35D area is characterized by dominant oxidic soil cover of relatively stable aggregate whose iron oxide enrichment could be attributed to inculcation of dolerite debris. Overall, the soil erodibility indices showed that the development of gully erosion in Tsitsa catchment is driven by high clay dispersivity ratio of the soil (mean = 0.70; 24percent CV), and poor soil structure relative to the low WSA range (18.1 – 34.0). Erodibility due to high sodicity are associated with saprolite (ESP = 8.02) and gleyic soils (ESP = 7.43) while the high soil dispersion was due to the vertic (46percent), duplex (38percent), cumulic (30percent), and lithic (27percent) soil components. The poor soil aggregates (WSA) were mainly controlled by the lithic (10percent), vertic (27percent), duplex (28percent), cumulic (31percent), and gleyic (34percent) soil components. Meanwhile, the T35E area is dominated by the dispersive and collapsible soils dominated by saprolites and lithic soils. Therefore, the environmental stakeholders are advised to adopt the best management practices within the dam area considering the vulnerability of the catchment to the development of gullies and the potential impact of sedimentation on the adequate performance of Tsitsa dam and its water infrastructures. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
- Authors: Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Date: 2022-01
- Subjects: Soil erosion , River sediments
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22677 , vital:52642
- Description: This study evaluated soil inherent properties for the development of gullies and their erodibility potential using the holistic field and laboratory sample investigation approach. The potential of negative impact of sedimentation on dam and water infrastructure performance has raised the need to evaluate the factors promoting soil erosion leading to land degradation. The study aimed to assess the relationship among the selected properties of soil and variability among various soil groups. A case study design approach was adopted at the T35D and T35E areas of Tsitsa hydrologic Basin, Eastern Cape, South Africa. The task was accomplished through detailed random soil sampling in the field, soil chemical analysis and comparative analysis of soil variables. Based on the scope of the study soil laboratory analysis included the following: particle size distribution, soil textural analysis, physicochemical parameters analysis, macro-and-micronutrient analysis, and micro-porosity analysis. Further spatial and scenario analysis of soil erodibility was done using selected erodibility indices such as Sodium Adsorption Ratio (SAR), Exchangeable Sodium Percentage (ESP), Dispersivity Ratio (DR), Clay Dispersion Ratio (CDR), Clay Flocculation Index (CFI), Water-Stable Aggregate analysis (WSA), and Soil Erodibility factor analysis (KEF). The findings of the study showed that the catchment hosts sixteen distinct soil forms categorized into seven unique soil groups. The results further indicated that the Katspruit soil form of the gleyic soil group has the highest clay-size particles and a considerably high clay dispersion attribute among others soil forms. It was further deduced that gleyic soil type exhibited the highest soil pH (6.36), a considerably low Ca:Mg ratio (1.43), a substantially high sodium ion (0.50 mg/kg), the highest SAR (0.5), lowest WSA (0.018percent) and a substantially high KEF (0.018ab). Similarly, saprolite soils exhibited the nature of the lixisol with a virtually equal amount of clay (43.63percent) and fine sands (41.68percent), the lowest amount of Ca:Mg ratio (1.35), the highest acid saturation (50.59), the highest ESP (8.39), and a considerably high WSA (38.75). Other remarkable problematic soils identified in the study include the lithic soil and the duplex soil. For instance, the Lithic soil is characterized by the highest fine sand-size texture (61.38percent), considerably low organic carbon (2.63percent), low cation exchange capacity (3.55 cmol(+)/kg), much high DR (0.75), very low WSA (0.027percent), and the highest KEF (0.027a). Whereas, the duplex soil is characterized by the highest DR (0.81), critically high CDR (38.19percent), very low WSA (0.019percent), and a considerably high KEF (0.019a). The relatively stable soils within the catchment are the oxidic, and melanic, where the WSA is highest in oxidic (38.19percent) and relatively high for melanic (36.6percent), CFI is highest in melanic (85.02percent), and oxidic (74.32percent), and KEF is relatively low (0.016b) for both. Correlation of the selected soil erodibility indices shows that CFI shares a perfect inverse relationship with CDR while maintaining a strong significant relationship with DR (R = -0.504). Findings also show that the SAR expectedly produced a robust significant relationship with ESP (R = 0.644), while KEF exhibited a solid inverse relationship with WSA (R = 0.913). The correlation across the physical and chemical properties suggests that DR and CDR can be firmly and positively influenced by dispersive clay. At the same time, the two factors maintain a significantly negative relationship with dispersive sand. Also, clay-sized particles depicted a significant relationship with WSA. Physicochemical and chemical parameters influence only the ESP and SAR. A remarkable finding is the influence of iron and its presence on SAR. On the other hand, ESP was distinguished from SAR due to the inverse influence of potassium. The lithic soils identify as members of the collapsible soil of South Africa, while the gleyic soils identify with duplex and saprolite soils in the class of dispersive soils. The vertic soils characterize as expansive soil, while the Duplex soil also exhibits a soft soil attribute. In general, the study suggests that T35D and T35E areas of Tsitsa catchment vary spatially in soil erodibility potential. T35D area is characterized by dominant oxidic soil cover of relatively stable aggregate whose iron oxide enrichment could be attributed to inculcation of dolerite debris. Overall, the soil erodibility indices showed that the development of gully erosion in Tsitsa catchment is driven by high clay dispersivity ratio of the soil (mean = 0.70; 24percent CV), and poor soil structure relative to the low WSA range (18.1 – 34.0). Erodibility due to high sodicity are associated with saprolite (ESP = 8.02) and gleyic soils (ESP = 7.43) while the high soil dispersion was due to the vertic (46percent), duplex (38percent), cumulic (30percent), and lithic (27percent) soil components. The poor soil aggregates (WSA) were mainly controlled by the lithic (10percent), vertic (27percent), duplex (28percent), cumulic (31percent), and gleyic (34percent) soil components. Meanwhile, the T35E area is dominated by the dispersive and collapsible soils dominated by saprolites and lithic soils. Therefore, the environmental stakeholders are advised to adopt the best management practices within the dam area considering the vulnerability of the catchment to the development of gullies and the potential impact of sedimentation on the adequate performance of Tsitsa dam and its water infrastructures. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
The use of earth observation multi-sensor systems to monitor and model Pastures: a case of Savannah Grasslands in Hluvukani Village, Bushbuckridge Local Municipality, Mpumalanga Province, South Africa
- Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Authors: Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Date: 2022-01
- Subjects: Climatic changes , Grassland conservation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22578 , vital:52470
- Description: Grassland degradation associated with climate change and inappropriate grassland management has been characterized as a global environmental concern driving decreased grassland ecosystem's ecological functioning. More than 60% of South African grassland is degraded or permanently transformed to other land uses and nearly 2% properly conserved. Yet, grasslands are a major source of food for livestock grazing and provide material and non-material benefits to many livelihoods. Therefore, grassland above-ground biomass (AGB) estimation is crucial in planning and managing pastoral agriculture and the benefits derived from it. However, current grassland monitoring techniques used in rural smallholder livestock farms rely on conventional methods, which are destructive, labour-intensive, costly, and restricted to small areas. This study investigated the monitoring and modelling of protected grasslands biomass using current Earth observation systems (EOS), an approach, which is non-destructive, cost-effective, cover larger areas and is a time-saving alternative to conventional methods. Hence, the research objectives were: (i) to map the trends and advances in data and models used in the monitoring of grassland (pastures) with Earth observation systems, and (ii) to assess above-ground biomass estimation in semi-arid savannah grassland integrating Sentinel-1 and Sentinel-2 data with Machine-Learning. This goal was to assess if this approach could provide the requisite information, which could contribute to the long-term goal of developing a semi-automated system for data processing, and mapping grassland biomass to benefit local communities. For this investigation, it was crucial to understanding what research had achieved so far in this area of pasture management. An assessment of the Scopus database showed the recent developments in European Union (EU) programs and Sentinel missions, including statistical models and machine learning for monitoring grassland changes at multiple scales. However, Sentinel-1 and Sentinel-2 data, machine learning models, and variable importance techniques were applied for grassland AGB estimation. These techniques have been used in similar studies to determine optimum machine learning models, influential variables, and the capability of integrated Sentinel datasets for mapping grassland AGB, spatial distribution, and abundance. Results showed improved performance with the Random forest regression (RFR) model (R² of 34.7%, RMSE of 9.47 Mg and MAE of 7.68 Mg ). The study also observed optimum sensitivity of Difference Vegetation Index (DVI) and Enhanced Vegetation Index (EVI) in all three machine learning models for modelling grassland AGB estimation in the study area. A further, statistical comparison of all three machine learning models showed an insignificant difference in the predictive capacity for AGB in the study area with Gradient Boosting regression (GBR) model (R² of 27.7, RMSE of 9.97 Mg and MAE of 8.03 Mg ) and Extreme Gradient Boost Regression (XGBR) model (R² of 17.3%, RMSE of 10.66 Mg and MAE of 8.83 Mg ). The study revealed that an integration of Sentinel-1 and Sentinel-2 has improved capabilities for monitoring grassland AGB estimation. This research sheds light on the timely and cost-effective techniques for grassland management strategies to enhance or restore the ecological functioning of grassland ecosystems and promote community sustainability. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
- Authors: Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Date: 2022-01
- Subjects: Climatic changes , Grassland conservation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22578 , vital:52470
- Description: Grassland degradation associated with climate change and inappropriate grassland management has been characterized as a global environmental concern driving decreased grassland ecosystem's ecological functioning. More than 60% of South African grassland is degraded or permanently transformed to other land uses and nearly 2% properly conserved. Yet, grasslands are a major source of food for livestock grazing and provide material and non-material benefits to many livelihoods. Therefore, grassland above-ground biomass (AGB) estimation is crucial in planning and managing pastoral agriculture and the benefits derived from it. However, current grassland monitoring techniques used in rural smallholder livestock farms rely on conventional methods, which are destructive, labour-intensive, costly, and restricted to small areas. This study investigated the monitoring and modelling of protected grasslands biomass using current Earth observation systems (EOS), an approach, which is non-destructive, cost-effective, cover larger areas and is a time-saving alternative to conventional methods. Hence, the research objectives were: (i) to map the trends and advances in data and models used in the monitoring of grassland (pastures) with Earth observation systems, and (ii) to assess above-ground biomass estimation in semi-arid savannah grassland integrating Sentinel-1 and Sentinel-2 data with Machine-Learning. This goal was to assess if this approach could provide the requisite information, which could contribute to the long-term goal of developing a semi-automated system for data processing, and mapping grassland biomass to benefit local communities. For this investigation, it was crucial to understanding what research had achieved so far in this area of pasture management. An assessment of the Scopus database showed the recent developments in European Union (EU) programs and Sentinel missions, including statistical models and machine learning for monitoring grassland changes at multiple scales. However, Sentinel-1 and Sentinel-2 data, machine learning models, and variable importance techniques were applied for grassland AGB estimation. These techniques have been used in similar studies to determine optimum machine learning models, influential variables, and the capability of integrated Sentinel datasets for mapping grassland AGB, spatial distribution, and abundance. Results showed improved performance with the Random forest regression (RFR) model (R² of 34.7%, RMSE of 9.47 Mg and MAE of 7.68 Mg ). The study also observed optimum sensitivity of Difference Vegetation Index (DVI) and Enhanced Vegetation Index (EVI) in all three machine learning models for modelling grassland AGB estimation in the study area. A further, statistical comparison of all three machine learning models showed an insignificant difference in the predictive capacity for AGB in the study area with Gradient Boosting regression (GBR) model (R² of 27.7, RMSE of 9.97 Mg and MAE of 8.03 Mg ) and Extreme Gradient Boost Regression (XGBR) model (R² of 17.3%, RMSE of 10.66 Mg and MAE of 8.83 Mg ). The study revealed that an integration of Sentinel-1 and Sentinel-2 has improved capabilities for monitoring grassland AGB estimation. This research sheds light on the timely and cost-effective techniques for grassland management strategies to enhance or restore the ecological functioning of grassland ecosystems and promote community sustainability. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
Bayesian spatio-temporal zero-inflated mixed models for overdispersion on chronic disease mapping
- Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
Sediment characteristics and hydrodynamic conditions of the Swartkops estuary, Eastern Cape Province of South Africa
- Best, Lutho https://orcid.org/0000-0001-6400-9061
- Authors: Best, Lutho https://orcid.org/0000-0001-6400-9061
- Date: 2021-11
- Subjects: Geology, Stratigraphic , Estuarine oceanography , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22611 , vital:52596
- Description: This study is a part of an environmental research project aimed at providing assessment information to the grain-size distribution, mineral compositions, sedimentary structures and coastal erosion and rehabilitation methods along the Swartkops estuary, a recent developing industry area of South Africa. The methodologies used in this study comprise desk study of literature, field geological investigation and sampling, and laboratory analyses including grainsize analysis, thin section microscope study, XRD mineral composition study and SEM-EDX grain surface texture and composition analyses.The basement and surrounding areas of the Swartkops estuary consist of three formations: the Enon Formation of mainly conglomerate, the Kirkwood Formation of sandstone and mudstone, and the Sundays River Formation of dominantly mudstone with sandstone, which integrated as Uitenhage Group of Cretaceous sequence with modern estuarine sand and alluvial sediments filled in the entire basin. Grain size analysis is a useful tool to assess hydrodynamic environments. The grain size parameters showed that most of the Swartkops estuary sediments are moderately sorted with very few well and poorly sorted, coarse to fine skewed in grain size distribution.Whereas the Bluewater Bay beach sediments are mostly fine grained, well sorted, fine to coarse skewed in grain size distribution. The bivariate scatter plots are an indication of shallow marine environment by beach and coastal processes with the influence of water flow and wind influence during transportation and deposition processes. Mineralogy studies revealed that the Swartkops estuary sediments are dominantly composed of minerals such as: quartz, calcite, feldspar (orthoclase and plagioclase), aragonite, clay minerals (smectite and illite), and salts such as NaCl and MgCl2. Skeletal carbonate minerals (shell fragments) are more than chemical precipitated carbonate minerals. Quartz is the most abundant detrital mineral observed in all the sediments and it comes from inland and transported into the estuary and the beach by fluvial streams, whereas skeletal calcite/aragonite is the most abundant biogenic carbonate derived from sea side and transported by marine currents. The study shows that grain surface textures reveal the existence of several features that reflect the depositional environments. Observed grain surface textures by microscope and SEM include V-shape pits, upturned pits caused by mechanical crashing and corrosion during transportation; crystalline precipitation of calcite, quartz, salt and clay by chemical precipitation and crystallization; dissolution pits and pores formed by dissolution, and burrow and boring by biogenetic activities. The grain surface morphologies are closely linked to different formation mechanisms and depositional environments. Well-developed sedimentary structures have been found in the beach and estuary, including sand dune, sand ridge, straight and sinuous ripple, ripple marks, aeolian nail marks, high angle tabular cross bedding, antidune, rill mark, rhomboid mark, swash line, mud crack, gravel pavement, interfering ripples, flat topped ripple mark, linguiod mark, asymmetric sinuous ripples, dendritic pattern on sandy beach, boring and bioturbation, burrows desiccation cracks and water escape hole. Different sedimentary structures are reflective of different hydrodynamic conditions and depositional environments. Coastal erosion is a major problem for damage of road, bridge and properties in the industrial areas in Swartkops, which is also a task for this study. The author had suggested some practical mitigation-methods to local government, such as groins, revetments, shoreline hardening, planting of vegetation, and vertical walls, bulkheads, sills, which could be useful for the protection of coastal erosion. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
- Authors: Best, Lutho https://orcid.org/0000-0001-6400-9061
- Date: 2021-11
- Subjects: Geology, Stratigraphic , Estuarine oceanography , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22611 , vital:52596
- Description: This study is a part of an environmental research project aimed at providing assessment information to the grain-size distribution, mineral compositions, sedimentary structures and coastal erosion and rehabilitation methods along the Swartkops estuary, a recent developing industry area of South Africa. The methodologies used in this study comprise desk study of literature, field geological investigation and sampling, and laboratory analyses including grainsize analysis, thin section microscope study, XRD mineral composition study and SEM-EDX grain surface texture and composition analyses.The basement and surrounding areas of the Swartkops estuary consist of three formations: the Enon Formation of mainly conglomerate, the Kirkwood Formation of sandstone and mudstone, and the Sundays River Formation of dominantly mudstone with sandstone, which integrated as Uitenhage Group of Cretaceous sequence with modern estuarine sand and alluvial sediments filled in the entire basin. Grain size analysis is a useful tool to assess hydrodynamic environments. The grain size parameters showed that most of the Swartkops estuary sediments are moderately sorted with very few well and poorly sorted, coarse to fine skewed in grain size distribution.Whereas the Bluewater Bay beach sediments are mostly fine grained, well sorted, fine to coarse skewed in grain size distribution. The bivariate scatter plots are an indication of shallow marine environment by beach and coastal processes with the influence of water flow and wind influence during transportation and deposition processes. Mineralogy studies revealed that the Swartkops estuary sediments are dominantly composed of minerals such as: quartz, calcite, feldspar (orthoclase and plagioclase), aragonite, clay minerals (smectite and illite), and salts such as NaCl and MgCl2. Skeletal carbonate minerals (shell fragments) are more than chemical precipitated carbonate minerals. Quartz is the most abundant detrital mineral observed in all the sediments and it comes from inland and transported into the estuary and the beach by fluvial streams, whereas skeletal calcite/aragonite is the most abundant biogenic carbonate derived from sea side and transported by marine currents. The study shows that grain surface textures reveal the existence of several features that reflect the depositional environments. Observed grain surface textures by microscope and SEM include V-shape pits, upturned pits caused by mechanical crashing and corrosion during transportation; crystalline precipitation of calcite, quartz, salt and clay by chemical precipitation and crystallization; dissolution pits and pores formed by dissolution, and burrow and boring by biogenetic activities. The grain surface morphologies are closely linked to different formation mechanisms and depositional environments. Well-developed sedimentary structures have been found in the beach and estuary, including sand dune, sand ridge, straight and sinuous ripple, ripple marks, aeolian nail marks, high angle tabular cross bedding, antidune, rill mark, rhomboid mark, swash line, mud crack, gravel pavement, interfering ripples, flat topped ripple mark, linguiod mark, asymmetric sinuous ripples, dendritic pattern on sandy beach, boring and bioturbation, burrows desiccation cracks and water escape hole. Different sedimentary structures are reflective of different hydrodynamic conditions and depositional environments. Coastal erosion is a major problem for damage of road, bridge and properties in the industrial areas in Swartkops, which is also a task for this study. The author had suggested some practical mitigation-methods to local government, such as groins, revetments, shoreline hardening, planting of vegetation, and vertical walls, bulkheads, sills, which could be useful for the protection of coastal erosion. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
Study on the effect of shade net on internal and external quality parameters and chilling injury of fruits of citrus species in the Eastern Cape Province of South Africa
- Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Authors: Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Date: 2021-11
- Subjects: Fruit-culture , Horticulture , Citrus fruits
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22622 , vital:52600
- Description: Pre-harvest technology of shade net is environmental friendly and was found previously to improve fruit growth and yield. In addition, it reduces wind blemishes and sunburn, and effectively act as a buffer against climate fluctuations, such as excessive light, wind and hail damages. However, commercial shade nets are capital intensive; therefore, it is important for farmers to understand its impact on fruit quality that is desired for export market and assess whether the investment is profitable to the industry or not. It was brought to attention that several citrus cultivars grown in Addo, Eastern Cape under 20percent commercial shade net shows sensitivity to chilling injury (CI); however. no information is yet documented about the impact of this technology on fruit quality. To determine the efficacy of 20percent-shade net technology in relation to the control (no shade net), the present study was designed with the objective to compare internal and external quality parameters of ‘Washington and Cambria’ navels, ‘Valley Gold’ mandarin, and ‘Eureka’ lemon fruit grown in shade netted orchards and stored at low temperatures (4 and -0.6°C) for 30 days in Addo area, Eastern Cape. Internal quality attributes assessed includes juice content, °Brixpercent, titratable acid (TA), °Brix:acid ratio and average number of seeds. External quality data assessed include rind colour, and fruit size, firmness/texture and fresh weight loss. For chilling injury, fruits were evaluated by examining the degree of rind pitting and assigning levels of severity namely 0, 1, 2 or 3 where 0 = no pitting detected, 1 = 1 pit, 2 = 2 or more pitting detected and 3 = severe pitting detected. The post-harvest experiments were done on fruits harvested from commercial citrus orchards in Sundays River Valley, between Kirkwood and Addo (33° 34' 0" South, 25° 41' 0" East), in the Eastern Cape Province of South Africa, over two harvesting seasons (2018 and 2019). The ‘Eureka’ lemon and ‘Washington navel’ fruit were collected from Allendale farm; the ‘Cambria’ navel fruits from the Nuwelande and Olifantsbos farms; and the ‘Valley Gold’ mandarin fruits from the Dunbrody/Unifruitti farm. The quality attributes were recorded in the Laboratory of the Citrus Research International (CRI), Port Elizabeth, Eastern Cape, South Africa during Season 1, and in the Horticulture lab of the University of Fort Hare (UFH), Alice, Eastern Cape, South, Africa during Season 2. The experimental layout was a typical pseudo randomised completely block design (RCBD) (not truly randomised) whereby treatments tested were subjected over time (pre-test, post-test). The two treatments i.e. shade vs. control (no shade net) could not be randomly allocated to orchards due to the practical issue of working on a commercial farm, . The sub-factor consisted of three postharvest treatments: Ambiemt temperature (at 0 days storage), 4°C and -0.6°C storages for 30 days. Secondly, an experiment to evaluate the impact of petroleum-based wax mixed with 2-(4-thiazolyl) benzimidazole [thiabendazole (TBZ)] (TBZ: 500 mg.L-1) on shade net vs control fruits was conducted. The fruits were stored at 4°C and - 0.6°C (coated) for 30 days and were evaluated after 7 days storage at room temperature. Shade net did not significantly affect the internal quality attributes of citrus fruits. The 20percent- shade net promoted size of ‘Washington’, ‘Cambria’ navels and ‘Valley Gold’ mandarin, whilst rind colour was not affect. Firmness loss was higher on ‘Eureka’ lemon and ‘Washington’ navel, regardless of the growing conditions and cold storage duration. Rind firmness of ‘Cambria’ navel and ‘Valley Gold’ mandarin were not significantly affected by shade net and storage duration. ‘Eureka’ lemon was found to be more sensitive to CI. However, the application of wax+ TBZ eliminated CI on all 4-cultivars. Therefore, it is recommended to apply wax+ TBZ in packline to eliminate CI and fungal development. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
- Authors: Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Date: 2021-11
- Subjects: Fruit-culture , Horticulture , Citrus fruits
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22622 , vital:52600
- Description: Pre-harvest technology of shade net is environmental friendly and was found previously to improve fruit growth and yield. In addition, it reduces wind blemishes and sunburn, and effectively act as a buffer against climate fluctuations, such as excessive light, wind and hail damages. However, commercial shade nets are capital intensive; therefore, it is important for farmers to understand its impact on fruit quality that is desired for export market and assess whether the investment is profitable to the industry or not. It was brought to attention that several citrus cultivars grown in Addo, Eastern Cape under 20percent commercial shade net shows sensitivity to chilling injury (CI); however. no information is yet documented about the impact of this technology on fruit quality. To determine the efficacy of 20percent-shade net technology in relation to the control (no shade net), the present study was designed with the objective to compare internal and external quality parameters of ‘Washington and Cambria’ navels, ‘Valley Gold’ mandarin, and ‘Eureka’ lemon fruit grown in shade netted orchards and stored at low temperatures (4 and -0.6°C) for 30 days in Addo area, Eastern Cape. Internal quality attributes assessed includes juice content, °Brixpercent, titratable acid (TA), °Brix:acid ratio and average number of seeds. External quality data assessed include rind colour, and fruit size, firmness/texture and fresh weight loss. For chilling injury, fruits were evaluated by examining the degree of rind pitting and assigning levels of severity namely 0, 1, 2 or 3 where 0 = no pitting detected, 1 = 1 pit, 2 = 2 or more pitting detected and 3 = severe pitting detected. The post-harvest experiments were done on fruits harvested from commercial citrus orchards in Sundays River Valley, between Kirkwood and Addo (33° 34' 0" South, 25° 41' 0" East), in the Eastern Cape Province of South Africa, over two harvesting seasons (2018 and 2019). The ‘Eureka’ lemon and ‘Washington navel’ fruit were collected from Allendale farm; the ‘Cambria’ navel fruits from the Nuwelande and Olifantsbos farms; and the ‘Valley Gold’ mandarin fruits from the Dunbrody/Unifruitti farm. The quality attributes were recorded in the Laboratory of the Citrus Research International (CRI), Port Elizabeth, Eastern Cape, South Africa during Season 1, and in the Horticulture lab of the University of Fort Hare (UFH), Alice, Eastern Cape, South, Africa during Season 2. The experimental layout was a typical pseudo randomised completely block design (RCBD) (not truly randomised) whereby treatments tested were subjected over time (pre-test, post-test). The two treatments i.e. shade vs. control (no shade net) could not be randomly allocated to orchards due to the practical issue of working on a commercial farm, . The sub-factor consisted of three postharvest treatments: Ambiemt temperature (at 0 days storage), 4°C and -0.6°C storages for 30 days. Secondly, an experiment to evaluate the impact of petroleum-based wax mixed with 2-(4-thiazolyl) benzimidazole [thiabendazole (TBZ)] (TBZ: 500 mg.L-1) on shade net vs control fruits was conducted. The fruits were stored at 4°C and - 0.6°C (coated) for 30 days and were evaluated after 7 days storage at room temperature. Shade net did not significantly affect the internal quality attributes of citrus fruits. The 20percent- shade net promoted size of ‘Washington’, ‘Cambria’ navels and ‘Valley Gold’ mandarin, whilst rind colour was not affect. Firmness loss was higher on ‘Eureka’ lemon and ‘Washington’ navel, regardless of the growing conditions and cold storage duration. Rind firmness of ‘Cambria’ navel and ‘Valley Gold’ mandarin were not significantly affected by shade net and storage duration. ‘Eureka’ lemon was found to be more sensitive to CI. However, the application of wax+ TBZ eliminated CI on all 4-cultivars. Therefore, it is recommended to apply wax+ TBZ in packline to eliminate CI and fungal development. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
Assessing the local awareness and perception of invasive alien plants: A case study of Port St Johns Local Municipality, Eastern Cape Province, South Africa
- Authors: Somkala, Avela Abongile
- Date: 2021-10
- Subjects: Alien plants , Invasive plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22600 , vital:52595
- Description: Invasive alien plants (IAPs) are introduced species that constitute a self-sustaining population, consistently producing offspring in large numbers and at considerable distances from the parent plants with the potential to spread over a large area. Species invasions are one of the main conservation threats today and have caused modification of ecosystems, particularly in coastal areas. Therefore, Port St Johns Local Municipality (PSJ LM) was an appropriate study site to evaluate the local awareness and perceptions of IAPs. The study investigated the local community’s perceptions of invasive alien plants' uses and ecological impacts. Information about the local awareness and perceptions of invasive alien plant species in PSJ LM was gathered through semi-structured interviews, observation and guided field walks with 120 participants between February and April 2021. The participants included 30 people working on the alien plant eradication project in PSJ LM (Wards 1, 2 and 3) and 90 randomly selected community members. The data collected were entered in Microsoft Excel 2016 programme and analyzed for descriptive statistical patterns using Statistical Package for Social Studies (SPSS) version 22.0. Biological invasion by IAPs was ubiquitously perceived, with participants working on invasive alien plant eradication project in the area exhibiting more scientifically based knowledge on IAPs than ordinary community members. Invasive alien plants in the area appear to have adverse environmental and socio-economic impacts, as the participants are not benefiting from these plant species. Similarly, costs of eradicating these species were also acknowledged. The ability of local community members to identify IAPs is vital in effective management of the spread of these species. A total of seven invasive IAPs were recorded. Evaluating the perceptions of local people towards IAPs provides valuable insights for development planning and future management programmes focusing on biological invasions. The study will provide a basis for an enabling policy and institutional environment that provides a coherent framework for the sustainable management of IAPs in the Eastern Cape Province. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Somkala, Avela Abongile
- Date: 2021-10
- Subjects: Alien plants , Invasive plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22600 , vital:52595
- Description: Invasive alien plants (IAPs) are introduced species that constitute a self-sustaining population, consistently producing offspring in large numbers and at considerable distances from the parent plants with the potential to spread over a large area. Species invasions are one of the main conservation threats today and have caused modification of ecosystems, particularly in coastal areas. Therefore, Port St Johns Local Municipality (PSJ LM) was an appropriate study site to evaluate the local awareness and perceptions of IAPs. The study investigated the local community’s perceptions of invasive alien plants' uses and ecological impacts. Information about the local awareness and perceptions of invasive alien plant species in PSJ LM was gathered through semi-structured interviews, observation and guided field walks with 120 participants between February and April 2021. The participants included 30 people working on the alien plant eradication project in PSJ LM (Wards 1, 2 and 3) and 90 randomly selected community members. The data collected were entered in Microsoft Excel 2016 programme and analyzed for descriptive statistical patterns using Statistical Package for Social Studies (SPSS) version 22.0. Biological invasion by IAPs was ubiquitously perceived, with participants working on invasive alien plant eradication project in the area exhibiting more scientifically based knowledge on IAPs than ordinary community members. Invasive alien plants in the area appear to have adverse environmental and socio-economic impacts, as the participants are not benefiting from these plant species. Similarly, costs of eradicating these species were also acknowledged. The ability of local community members to identify IAPs is vital in effective management of the spread of these species. A total of seven invasive IAPs were recorded. Evaluating the perceptions of local people towards IAPs provides valuable insights for development planning and future management programmes focusing on biological invasions. The study will provide a basis for an enabling policy and institutional environment that provides a coherent framework for the sustainable management of IAPs in the Eastern Cape Province. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10