Investigating the in-vitro anti-diabetic, anti- Alzheimer and antioxidant activities of Schiff base vanadium complexes
- Onyekwuluje, Chiamaka Mary-Ann
- Authors: Onyekwuluje, Chiamaka Mary-Ann
- Date: 2022-10
- Subjects: Diabetes , Alzheimer's disease , Oxidative stress , Vanadium compounds , Inhibition
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489259 , vital:80174
- Description: Diabetes mellitus (DM) and Alzheimer’s disease (AD) characterised by their progressive debilitating effects have secured spots in the list of the leading causes of morbidity and mortality worldwide. Despite intensive research and clinically available drugs, finding a cure to both diseases has remained elusive. Several therapeutic strategies have been developed to manage these diseases but majority of treatment options result in various side effects and are merely management rather than curative therapies. Current oral therapeutic agents used in the treatment of diabetes may be helpful at the initial stages. However, as patients progress towards complete beta cell failure, the efficacy of these oral agents diminishes and dependence on insulin therapy becomes inevitable in other to maintain normoglycemia and prevent diabetic complications. Similarly, the impact of AD therapies on cognitive functions, quality of life and their clinical significance are marginal to non-existent. Common aetiological features of DM and AD have been established and oxidative stress and inflammation are examples of some of common linkages identified. Therefore, this study was conducted to identify possible drug candidates with a potential to target multiple pathways envisaged to bring about the desired therapeutic effect in DM and AD, see the graphical abstract in Appendix 6. This multitarget approach seeks to address drug-related interactions associated with polypharmacy but also seeks to find lead molecules with the potential to provide better pharmacological management compared to conventional therapies. Schiff base vanadium complexes were selected for this study due to their diverse application and reported biological activities. In-vitro studies were augmented with physicochemical and pharmacokinetic predictions to assess the druggability and physicochemical properties of the vanadium complexes, which plays a role in their overall activity, bioavailability and their safety profiles. Molecular docking simulation was carried out where indicated to assess the preliminary mode of action of these Schiff base complexes. The three synthesized Schiff base vanadium complexes at 20, 40, 60, 80 and 100 μg/mL concentrations were evaluated in-vitro for inhibitory activity against α-glucosidase, α-amylase, and dipeptidyl peptidase-4 (DPP-4). These complexes were also evaluated for inhibitory activity against acetylcholinesterase, matrix metalloproteinase-1 (MMP-1) enzymes, advanced glycation end products and beta amyloid aggregation. The antioxidant capabilities of these compounds were also investigated. Reference compounds were used to validate the assay protocols and the data obtained by spectrophotometric/fluorometric analysis were converted to percentage inhibitions. Enzyme kinetic studies were conducted using the Lineweaver Burk plot. One-way ANOVA was performed to test for statistical significance at p value ≤0.05 using GraphPad prism 6. Statistically separate introduction of vanadium complexes showed significant inhibition as measured with α-glucosidase, DPP-4 and antioxidant assays. On the other hand, minimal inhibitory activity was observed for alpha amylase(α-amylase), acetylcholinesterase, beta amyloid aggregation and advanced glycation end products in comparison with the control. In contrast, enzyme activation was observed with MMP-1. The vanadium complexes were predicted to have drug-like characteristics according to Lipinski parameters; however, their predicted gastrointestinal absorption and blood brain barrier permeability was poor as shown by their locations on the boiled egg model and other generated parameters. Of the three investigated vanadium complexes, vanadium complex 3 showed the most potential towards diabetes and Alzheimer’s disease. Based on the results obtained it is evident that these complexes show good anti-hyperglycaemic and antioxidant activity with minimal anti-Alzheimer activity. This study provides evidence to suggest that the Schiff base vanadium complexes may be promising candidates to explore in the control and management of hyperglycaemia, oxidative stress related complications. However, their predicted physicochemical properties may hinder their progress to further phases of drug discovery. This calls for further investigation into alternative means to improve their chemical properties to streamline their inhibitory actions towards multiple targets implicated in AD and DM pathogenesis. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
- Date Issued: 2022-10
- Authors: Onyekwuluje, Chiamaka Mary-Ann
- Date: 2022-10
- Subjects: Diabetes , Alzheimer's disease , Oxidative stress , Vanadium compounds , Inhibition
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489259 , vital:80174
- Description: Diabetes mellitus (DM) and Alzheimer’s disease (AD) characterised by their progressive debilitating effects have secured spots in the list of the leading causes of morbidity and mortality worldwide. Despite intensive research and clinically available drugs, finding a cure to both diseases has remained elusive. Several therapeutic strategies have been developed to manage these diseases but majority of treatment options result in various side effects and are merely management rather than curative therapies. Current oral therapeutic agents used in the treatment of diabetes may be helpful at the initial stages. However, as patients progress towards complete beta cell failure, the efficacy of these oral agents diminishes and dependence on insulin therapy becomes inevitable in other to maintain normoglycemia and prevent diabetic complications. Similarly, the impact of AD therapies on cognitive functions, quality of life and their clinical significance are marginal to non-existent. Common aetiological features of DM and AD have been established and oxidative stress and inflammation are examples of some of common linkages identified. Therefore, this study was conducted to identify possible drug candidates with a potential to target multiple pathways envisaged to bring about the desired therapeutic effect in DM and AD, see the graphical abstract in Appendix 6. This multitarget approach seeks to address drug-related interactions associated with polypharmacy but also seeks to find lead molecules with the potential to provide better pharmacological management compared to conventional therapies. Schiff base vanadium complexes were selected for this study due to their diverse application and reported biological activities. In-vitro studies were augmented with physicochemical and pharmacokinetic predictions to assess the druggability and physicochemical properties of the vanadium complexes, which plays a role in their overall activity, bioavailability and their safety profiles. Molecular docking simulation was carried out where indicated to assess the preliminary mode of action of these Schiff base complexes. The three synthesized Schiff base vanadium complexes at 20, 40, 60, 80 and 100 μg/mL concentrations were evaluated in-vitro for inhibitory activity against α-glucosidase, α-amylase, and dipeptidyl peptidase-4 (DPP-4). These complexes were also evaluated for inhibitory activity against acetylcholinesterase, matrix metalloproteinase-1 (MMP-1) enzymes, advanced glycation end products and beta amyloid aggregation. The antioxidant capabilities of these compounds were also investigated. Reference compounds were used to validate the assay protocols and the data obtained by spectrophotometric/fluorometric analysis were converted to percentage inhibitions. Enzyme kinetic studies were conducted using the Lineweaver Burk plot. One-way ANOVA was performed to test for statistical significance at p value ≤0.05 using GraphPad prism 6. Statistically separate introduction of vanadium complexes showed significant inhibition as measured with α-glucosidase, DPP-4 and antioxidant assays. On the other hand, minimal inhibitory activity was observed for alpha amylase(α-amylase), acetylcholinesterase, beta amyloid aggregation and advanced glycation end products in comparison with the control. In contrast, enzyme activation was observed with MMP-1. The vanadium complexes were predicted to have drug-like characteristics according to Lipinski parameters; however, their predicted gastrointestinal absorption and blood brain barrier permeability was poor as shown by their locations on the boiled egg model and other generated parameters. Of the three investigated vanadium complexes, vanadium complex 3 showed the most potential towards diabetes and Alzheimer’s disease. Based on the results obtained it is evident that these complexes show good anti-hyperglycaemic and antioxidant activity with minimal anti-Alzheimer activity. This study provides evidence to suggest that the Schiff base vanadium complexes may be promising candidates to explore in the control and management of hyperglycaemia, oxidative stress related complications. However, their predicted physicochemical properties may hinder their progress to further phases of drug discovery. This calls for further investigation into alternative means to improve their chemical properties to streamline their inhibitory actions towards multiple targets implicated in AD and DM pathogenesis. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
- Date Issued: 2022-10
A study of the catalysis of the Diels-Alder and Aldol Condensation Reactions
- Authors: Ndagano, Urbain Nshokano
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178525 , vital:42947
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Ndagano, Urbain Nshokano
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178525 , vital:42947
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
A Systematic Visualisation Framework for Radio-Imaging Pipelines
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
Alternative approach to controlling citrus black spot disease
- Authors: Thabede, Jahman Thabo
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178569 , vital:42951
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Thabede, Jahman Thabo
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178569 , vital:42951
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
An assessment of the wild cyclopia subternata (vleitee) resource
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
An exploratory investigation into an Integrated Vulnerability and Patch Management Framework
- Authors: Carstens, Duane
- Date: 2021-04
- Subjects: Computer security , Computer security -- Management , Computer networks -- Security measures , Patch Management , Integrated Vulnerability
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177940 , vital:42892
- Description: In the rapidly changing world of cybersecurity, the constant increase of vulnerabilities continues to be a prevalent issue for many organisations. Malicious actors are aware that most organisations cannot timeously patch known vulnerabilities and are ill-prepared to protect against newly created vulnerabilities where a signature or an available patch has not yet been created. Consequently, information security personnel face ongoing challenges to mitigate these risks. In this research, the problem of remediation in a world of increasing vulnerabilities is considered. The current paradigm of vulnerability and patch management is reviewed using a pragmatic approach to all associated variables of these services / practices and, as a result, what is working and what is not working in terms of remediation is understood. In addition to the analysis, a taxonomy is created to provide a graphical representation of all associated variables to vulnerability and patch management based on existing literature. Frameworks currently being utilised in the industry to create an effective engagement model between vulnerability and patch management services are considered. The link between quantifying a threat, vulnerability and consequence; what Microsoft has available for patching; and the action plan for resulting vulnerabilities is explored. Furthermore, the processes and means of communication between each of these services are investigated to ensure there is effective remediation of vulnerabilities, ultimately improving the security risk posture of an organisation. In order to effectively measure the security risk posture, progress is measured between each of these services through a single averaged measurement metric. The outcome of the research highlights influencing factors that impact successful vulnerability management, in line with identified themes from the research taxonomy. These influencing factors are however significantly undermined due to resources within the same organisations not having a clear and consistent understanding of their role, organisational capabilities and objectives for effective vulnerability and patch management within their organisations. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Carstens, Duane
- Date: 2021-04
- Subjects: Computer security , Computer security -- Management , Computer networks -- Security measures , Patch Management , Integrated Vulnerability
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177940 , vital:42892
- Description: In the rapidly changing world of cybersecurity, the constant increase of vulnerabilities continues to be a prevalent issue for many organisations. Malicious actors are aware that most organisations cannot timeously patch known vulnerabilities and are ill-prepared to protect against newly created vulnerabilities where a signature or an available patch has not yet been created. Consequently, information security personnel face ongoing challenges to mitigate these risks. In this research, the problem of remediation in a world of increasing vulnerabilities is considered. The current paradigm of vulnerability and patch management is reviewed using a pragmatic approach to all associated variables of these services / practices and, as a result, what is working and what is not working in terms of remediation is understood. In addition to the analysis, a taxonomy is created to provide a graphical representation of all associated variables to vulnerability and patch management based on existing literature. Frameworks currently being utilised in the industry to create an effective engagement model between vulnerability and patch management services are considered. The link between quantifying a threat, vulnerability and consequence; what Microsoft has available for patching; and the action plan for resulting vulnerabilities is explored. Furthermore, the processes and means of communication between each of these services are investigated to ensure there is effective remediation of vulnerabilities, ultimately improving the security risk posture of an organisation. In order to effectively measure the security risk posture, progress is measured between each of these services through a single averaged measurement metric. The outcome of the research highlights influencing factors that impact successful vulnerability management, in line with identified themes from the research taxonomy. These influencing factors are however significantly undermined due to resources within the same organisations not having a clear and consistent understanding of their role, organisational capabilities and objectives for effective vulnerability and patch management within their organisations. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
An investigation into the current state of web based cryptominers and cryptojacking
- Authors: Len, Robert
- Date: 2021-04
- Subjects: Cryptocurrencies , Malware (Computer software) , Computer networks -- Security measures , Computer networks -- Monitoring , Cryptomining , Coinhive , Cryptojacking
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178248 , vital:42924
- Description: The aim of this research was to conduct a review of the current state and extent of surreptitious crypto mining software and its prevalence as a means for income generation. Income is generated through the use of a viewer's browser to execute custom JavaScript code to mine cryptocurrencies such as Monero and Bitcoin. The research aimed to measure the prevalence of illicit mining scripts being utilised for “in-browser" cryptojacking while further analysing the ecosystems that support the cryptomining environment. The extent of the research covers aspects such as the content (or type) of the sites hosting malicious “in-browser" cryptomining software as well as the occurrences of currencies utilised in the cryptographic mining and the analysis of cryptographic mining code samples. This research aims to compare the results of previous work with the current state of affairs since the closure of Coinhive in March 2018. Coinhive were at the time the market leader in such web based mining services. Beyond the analysis of the prevalence of cryptomining on the web today, research into the methodologies and techniques used to detect and counteract cryptomining are also conducted. This includes the most recent developments in malicious JavaScript de-obfuscation as well as cryptomining signature creation and detection. Methodologies for heuristic JavaScript behaviour identification and subsequent identification of potential malicious out-liars are also included within the research of the countermeasure analysis. The research revealed that although no longer functional, Coinhive remained as the most prevalent script being used for “in-browser" cryptomining services. While remaining the most prevalent, there was however a significant decline in overall occurrences compared to when coinhive.com was operational. Analysis of the ecosystem hosting \in-browser" mining websites was found to be distributed both geographically as well as in terms of domain categorisations. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Len, Robert
- Date: 2021-04
- Subjects: Cryptocurrencies , Malware (Computer software) , Computer networks -- Security measures , Computer networks -- Monitoring , Cryptomining , Coinhive , Cryptojacking
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178248 , vital:42924
- Description: The aim of this research was to conduct a review of the current state and extent of surreptitious crypto mining software and its prevalence as a means for income generation. Income is generated through the use of a viewer's browser to execute custom JavaScript code to mine cryptocurrencies such as Monero and Bitcoin. The research aimed to measure the prevalence of illicit mining scripts being utilised for “in-browser" cryptojacking while further analysing the ecosystems that support the cryptomining environment. The extent of the research covers aspects such as the content (or type) of the sites hosting malicious “in-browser" cryptomining software as well as the occurrences of currencies utilised in the cryptographic mining and the analysis of cryptographic mining code samples. This research aims to compare the results of previous work with the current state of affairs since the closure of Coinhive in March 2018. Coinhive were at the time the market leader in such web based mining services. Beyond the analysis of the prevalence of cryptomining on the web today, research into the methodologies and techniques used to detect and counteract cryptomining are also conducted. This includes the most recent developments in malicious JavaScript de-obfuscation as well as cryptomining signature creation and detection. Methodologies for heuristic JavaScript behaviour identification and subsequent identification of potential malicious out-liars are also included within the research of the countermeasure analysis. The research revealed that although no longer functional, Coinhive remained as the most prevalent script being used for “in-browser" cryptomining services. While remaining the most prevalent, there was however a significant decline in overall occurrences compared to when coinhive.com was operational. Analysis of the ecosystem hosting \in-browser" mining websites was found to be distributed both geographically as well as in terms of domain categorisations. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
Anisotropic copper oxide nanorods decorated with gold and palladium nanoparticles and their enzymatic properties
- Authors: Sicwetsha, Simbongile
- Date: 2021-04
- Subjects: Nanoparticles , Artificial enzyme , Copper oxide , Peroxidase activity
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178547 , vital:42949
- Description: The synthesis of spherical CuO nanoparticles (CuONPs), copper oxide nanorods (CuONRs), CuONRs decorated with gold (CuONRs@Au1.0NPs), CuONRs decorated with palladium (CuONRs@Pd1.0NPs) and CuONRs decorated with gold and palladium (CuONRs@Au0.5/Pd 0.5NPs) was carried out. The successful preparation of these nanomaterials was confirmed using UV-vis, DLS (zeta potential), XRD, TEM and EDS. The nanoparticles were found to possess intrinsic peroxidase-like activity. The peroxidase-like activity of the nanoparticles was dependent on pH, temperature and enzyme substrate concentration. The investigation of the steady-state kinetic parameters showed that the peroxidase-like activity of the nanomaterials followed the Michaelis-Menten kinetics behaviour. The spherical CuONPs showed the Km = 1.12 mM and 1.14 mM for H2O2 and TMB respectively. The CuONRs showed the Km = 40.04 mM and 2.91 mM for H2O2 and TMB respectively. The CuONRs@Au1.0NPs showed the Km = 3.05 mM and 6.49 mM for H2O2 and TMB respectively. The CuONRs@Pd1.0NPs showed the Km = 0.13 mM and 2.59 mM for H2O2 and TMB respectively. The CuONRs@Au0.5/Pd0.5NPs showed the Km = 2.66 mM and Km = 19.70 mM for H2O2 and TMB respectively. The nanomaterials interact with hydrogen peroxide to produce hydroxyl radicals (OH·). Therefore, the production of reactive oxygen species (ROS) was investigated and detected using 1,3-diphenylisobenzofuran (DPBF) as a radical scavenger. The prepared nanomaterials were used in biosensing for the colorimetric detection of glucose. The LOD and LOQ for spherical CuONPs was 0.73 μM and 2.42 μM, for CuONRs was 0.13 μM and 0.42 μM, CuONRs@Au1.0NPs was 7.19 μM and 21.78 μM, for CuONRs@Pd1.0 NPs was 19.65 μM and 59.54 μM, and for CuONRs@Au0.5/Pd0.5NPs was 10.46 μM and 31.71 μM. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Sicwetsha, Simbongile
- Date: 2021-04
- Subjects: Nanoparticles , Artificial enzyme , Copper oxide , Peroxidase activity
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178547 , vital:42949
- Description: The synthesis of spherical CuO nanoparticles (CuONPs), copper oxide nanorods (CuONRs), CuONRs decorated with gold (CuONRs@Au1.0NPs), CuONRs decorated with palladium (CuONRs@Pd1.0NPs) and CuONRs decorated with gold and palladium (CuONRs@Au0.5/Pd 0.5NPs) was carried out. The successful preparation of these nanomaterials was confirmed using UV-vis, DLS (zeta potential), XRD, TEM and EDS. The nanoparticles were found to possess intrinsic peroxidase-like activity. The peroxidase-like activity of the nanoparticles was dependent on pH, temperature and enzyme substrate concentration. The investigation of the steady-state kinetic parameters showed that the peroxidase-like activity of the nanomaterials followed the Michaelis-Menten kinetics behaviour. The spherical CuONPs showed the Km = 1.12 mM and 1.14 mM for H2O2 and TMB respectively. The CuONRs showed the Km = 40.04 mM and 2.91 mM for H2O2 and TMB respectively. The CuONRs@Au1.0NPs showed the Km = 3.05 mM and 6.49 mM for H2O2 and TMB respectively. The CuONRs@Pd1.0NPs showed the Km = 0.13 mM and 2.59 mM for H2O2 and TMB respectively. The CuONRs@Au0.5/Pd0.5NPs showed the Km = 2.66 mM and Km = 19.70 mM for H2O2 and TMB respectively. The nanomaterials interact with hydrogen peroxide to produce hydroxyl radicals (OH·). Therefore, the production of reactive oxygen species (ROS) was investigated and detected using 1,3-diphenylisobenzofuran (DPBF) as a radical scavenger. The prepared nanomaterials were used in biosensing for the colorimetric detection of glucose. The LOD and LOQ for spherical CuONPs was 0.73 μM and 2.42 μM, for CuONRs was 0.13 μM and 0.42 μM, CuONRs@Au1.0NPs was 7.19 μM and 21.78 μM, for CuONRs@Pd1.0 NPs was 19.65 μM and 59.54 μM, and for CuONRs@Au0.5/Pd0.5NPs was 10.46 μM and 31.71 μM. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
Baculovirus synergism for improved management of false codling moth Thaumatotibia leucotreta Meyr. (Lepidoptera: Tortricidae)
- Authors: Taylor, David Graham
- Date: 2021-04
- Subjects: Baculoviruses , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Codling moth , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176942 , vital:42774
- Description: Baculoviruses are an environmentally friendly and effective agent for managing lepidopteran pests. This includes the management of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a serious pest of citrus in Southern Africa and a major threat to the South African citrus export industry. For more than 15 years, CrleGV-SA- based biopesticides have been used as part of an integrated pest management strategy for the control of T. leucotreta in citrus orchards in South Africa, under the names Cryptogran™ and Cryptex®. While these biopesticides have been effective during this period, there are some areas in which baculovirus use could potentially be improved. Baculoviruses are notoriously slow to kill in comparison to chemical-based pesticides, and lately, pest resistance to baculoviruses has become a major concern with the development of resistance by Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) to its granulovirus occurring in the field in Europe. The consistent use of CrleGV-SA for more than 15 years in the field has raised concern that T. leucotreta could develop resistance to this virus, and has made it necessary to alter baculovirus-based management strategies to prevent this from occurring. A second baculovirus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), has recently been isolated and was shown to be effective against T. leucotreta. However, the interactions between CrleGV-SA and CrpeNPV are not yet understood and so it is important to test these interactions before both viruses are applied on the same orchards. Not only is it important to know whether these viruses could negatively impact each other, but it is also important to test whether they could interact synergistically. A synergistic interaction could not only provide a potential tool for the management of resistance, but it could also be exploited to improve baculovirus-based management of T. leucotreta. In this study, a stock of CrleGV-SA was purified by glycerol gradient centrifugation from T. leucotreta cadavers, while a stock of CrpeNPV purified from Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) cadavers was provided by River Bioscience (Pty) Ltd. These stocks were screened for purity by a multiplex polymerase chain reaction (mPCR) protocol designed to detect CrleGV-SA and CrpeNPV. The occlusion body (OB) density was then calculated using darkfield microscopy and a counting chamber. Both stocks were shown to be pure within the limits of the mPCR protocol, and the CrleGV-SA and CrpeNPV stocks were calculated to contain 3.08 × 1011 OBs/mL and 1.92 × 1011 OBs/mL respectively The first aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the dose mortality, in terms of lethal concentration. This was calculated using 7-day surface-dose biological assays for each virus and a 1:1 mixture of OBs of the two against T. leucotreta neonates. The lethal concentrations of each treatment required to kill 50 % of larvae (LC50) and 90 % of larvae (LC90) for each treatment were then calculated and compared using a probit regression. The mixed infection performed significantly better than either virus by itself, while each virus by itself did not differ significantly from the other. The LC50 for CrleGV-SA, CrpeNPV and the mixed infection were 1.53 × 104 OBs/mL, 1.15 × 104 OBs/mL and 4.38 × 103 OBs/mL respectively. The LC90 of CrleGV-SA, CrpeNPV and the mixed infection were calculated to be 4.10 × 105 OBs/mL, 1.05 × 105 OBs/mL, and 4.09 × 104 OBs/mL respectively. The second aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the speed of kill. A time-response biological assay protocol was created that allowed for effective observation of the larvae. This was then used to generate time-mortality data that were analysed by a logit regression function to calculate and compare the treatments at the time of 50 % larval mortality (LT50) and the time of 90 % mortality (LT90). Each virus by itself did not differ significantly from the other, while the mixed infection took significantly longer to kill 50 % and 90 % of the larvae, suggesting that there is competition for resources between viruses during the secondary, systemic phase of infection. The LT50 for CrleGV-SA, CrpeNPV and the mixed infection were 117.5 hours, 113.5 hours and 139.0 hours respectively. The LT90 for CrleGV-SA, CrpeNPV and the mixed infection were 153.2 hours, 159.3, and 193.4 hours respectively. Finally, the composition of OBs recovered from the cadavers produced by the time-response biological assays were investigated by mPCR. A method for extracting gDNA from OBs in neonate-sized T. leucotreta larvae is described. The presence of CrpeNPV along with CrleGV-SA was noted in 4 out of 9 larvae inoculated with only CrleGV-SA. The presence of CrleGV-SA as well as CrpeNPV was noted in all but one larva inoculated with only CrpeNPV, and both CrleGV-SA and CrpeNPV were noted in all but one larva inoculated with a 1:1 mixture of the two, with one larva only being positive for CrleGV-SA. This suggests either stock contamination or the presence of covert infections of CrleGV-SA and CrpeNPV in the T. leucotreta population used in this study. This is the second study to report an improved lethal concentration of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates, and the first study to report the slower speed of kill of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates. While the improved lethal concentration of the mixed infection is a promising step in the future improvement of baculovirus-based biopesticides, it is at the cost of a slower speed of kill. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Taylor, David Graham
- Date: 2021-04
- Subjects: Baculoviruses , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Codling moth , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176942 , vital:42774
- Description: Baculoviruses are an environmentally friendly and effective agent for managing lepidopteran pests. This includes the management of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a serious pest of citrus in Southern Africa and a major threat to the South African citrus export industry. For more than 15 years, CrleGV-SA- based biopesticides have been used as part of an integrated pest management strategy for the control of T. leucotreta in citrus orchards in South Africa, under the names Cryptogran™ and Cryptex®. While these biopesticides have been effective during this period, there are some areas in which baculovirus use could potentially be improved. Baculoviruses are notoriously slow to kill in comparison to chemical-based pesticides, and lately, pest resistance to baculoviruses has become a major concern with the development of resistance by Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) to its granulovirus occurring in the field in Europe. The consistent use of CrleGV-SA for more than 15 years in the field has raised concern that T. leucotreta could develop resistance to this virus, and has made it necessary to alter baculovirus-based management strategies to prevent this from occurring. A second baculovirus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), has recently been isolated and was shown to be effective against T. leucotreta. However, the interactions between CrleGV-SA and CrpeNPV are not yet understood and so it is important to test these interactions before both viruses are applied on the same orchards. Not only is it important to know whether these viruses could negatively impact each other, but it is also important to test whether they could interact synergistically. A synergistic interaction could not only provide a potential tool for the management of resistance, but it could also be exploited to improve baculovirus-based management of T. leucotreta. In this study, a stock of CrleGV-SA was purified by glycerol gradient centrifugation from T. leucotreta cadavers, while a stock of CrpeNPV purified from Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) cadavers was provided by River Bioscience (Pty) Ltd. These stocks were screened for purity by a multiplex polymerase chain reaction (mPCR) protocol designed to detect CrleGV-SA and CrpeNPV. The occlusion body (OB) density was then calculated using darkfield microscopy and a counting chamber. Both stocks were shown to be pure within the limits of the mPCR protocol, and the CrleGV-SA and CrpeNPV stocks were calculated to contain 3.08 × 1011 OBs/mL and 1.92 × 1011 OBs/mL respectively The first aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the dose mortality, in terms of lethal concentration. This was calculated using 7-day surface-dose biological assays for each virus and a 1:1 mixture of OBs of the two against T. leucotreta neonates. The lethal concentrations of each treatment required to kill 50 % of larvae (LC50) and 90 % of larvae (LC90) for each treatment were then calculated and compared using a probit regression. The mixed infection performed significantly better than either virus by itself, while each virus by itself did not differ significantly from the other. The LC50 for CrleGV-SA, CrpeNPV and the mixed infection were 1.53 × 104 OBs/mL, 1.15 × 104 OBs/mL and 4.38 × 103 OBs/mL respectively. The LC90 of CrleGV-SA, CrpeNPV and the mixed infection were calculated to be 4.10 × 105 OBs/mL, 1.05 × 105 OBs/mL, and 4.09 × 104 OBs/mL respectively. The second aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the speed of kill. A time-response biological assay protocol was created that allowed for effective observation of the larvae. This was then used to generate time-mortality data that were analysed by a logit regression function to calculate and compare the treatments at the time of 50 % larval mortality (LT50) and the time of 90 % mortality (LT90). Each virus by itself did not differ significantly from the other, while the mixed infection took significantly longer to kill 50 % and 90 % of the larvae, suggesting that there is competition for resources between viruses during the secondary, systemic phase of infection. The LT50 for CrleGV-SA, CrpeNPV and the mixed infection were 117.5 hours, 113.5 hours and 139.0 hours respectively. The LT90 for CrleGV-SA, CrpeNPV and the mixed infection were 153.2 hours, 159.3, and 193.4 hours respectively. Finally, the composition of OBs recovered from the cadavers produced by the time-response biological assays were investigated by mPCR. A method for extracting gDNA from OBs in neonate-sized T. leucotreta larvae is described. The presence of CrpeNPV along with CrleGV-SA was noted in 4 out of 9 larvae inoculated with only CrleGV-SA. The presence of CrleGV-SA as well as CrpeNPV was noted in all but one larva inoculated with only CrpeNPV, and both CrleGV-SA and CrpeNPV were noted in all but one larva inoculated with a 1:1 mixture of the two, with one larva only being positive for CrleGV-SA. This suggests either stock contamination or the presence of covert infections of CrleGV-SA and CrpeNPV in the T. leucotreta population used in this study. This is the second study to report an improved lethal concentration of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates, and the first study to report the slower speed of kill of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates. While the improved lethal concentration of the mixed infection is a promising step in the future improvement of baculovirus-based biopesticides, it is at the cost of a slower speed of kill. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
Biology, ecology and management of the Keurboom moth, Leto venus Cramer and the leafhopper Molopopterus sp. Jacobi in cultivated Honeybush (Cyclopia spp.)
- Authors: Mushore, Tapiwa Gift
- Date: 2021-04
- Subjects: Legumes , Legumes -- Diseases and pests , Hepialidae , Leafhoppers , Pests -- Biological control , Entomopathogenic fungi , Leafhoppers -- Biological control , Hepialidae -- Biological control , Keurboom moth (Leto venus Cramer) , Molopopterus sp. Jacobi , Honeybush (Cyclopia spp.)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177125 , vital:42792
- Description: Honeybush, Cyclopia spp. Vent (Fabaceae), farmers have raised pest concerns following commercial cultivation. The Keurboom moth Leto venus Cramer (Lepidoptera: Hepialidae) and the leafhopper Molopopterus sp. Jacobi (Hemiptera: Cicadellidae), are two of the major pests identified in cultivated Honeybush. Laboratory and field studies were conducted to gain an understanding of the biology of these two pests to inform future pest management solutions. Additionally, entomopathogenic fungi were isolated from Honeybush farms and screened for virulence against Molopopterus sp. as a possible management strategy. This study showed that the L. venus infestation on Honeybush was a product of four fixed effects; stem diameter, species of Cyclopia, Farm location and age of the plants. Cyclopia subternata, had the highest likelihood of infestation. Increase in age of the plants resulted in an increase in the stem diameter and therefore a higher probability of infestation. Stem diameter was also shown to be a significant predictor of infestation likelihood. Infestation severity, determined by the number of larvae per plant, was shown to be influenced by three fixed effects; stem diameter, plant species and Farm location. The results also showed that L. venus prefers to initiate penetration at, or just aboveground level. Laboratory studies showed that the leafhopper Molopopterus sp. undergoes five nymphal instars with an average egg incubation time of 20 days, development time from 1st instar to adult of 26 days and average generation time of 47 days. Laboratory experiments revealed variations in host preference by the leafhopper over a period of 15 days. Cyclopia longifolia was identified to be the most preferred species for feeding compared to the two other commonly cultivated species, C. subternata and C. maculata. The results were consistent with those obtained from the field survey which showed that leafhopper density was influenced by four fixed effects; plant species, age of the plant, Farm location and harvesting practices. There were significant differences in leafhopper density in different species with C. longifolia having the highest number of leafhoppers per plant. There were differences in leafhopper density in different farms as 57% of the sampled farms had leafhopper infestations, of these farms, Lodestone and Kurland had the highest leafhopper densities. Harvested plants were shown to have significantly higher leafhopper density than non-harvested plants. Age was also shown to influence leafhopper density, which reduced with an increase in the age of the plants. A total of 20 fungal isolates were recovered from 98 soil samples of which 70% were from Honeybush fields and 30% were from surrounding refugia. Fusarium oxysporum isolates comprised 20% of the recovered isolates, with Metarhizium anisopliae isolates making up the remainder. Laboratory bioassays against adults and nymphs of the leafhopper, Molopopterus sp., showed that F. oxysporum isolates induced 10 – 45% mortality and M. anisopliae isolates induce 30 – 80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both Molopopterus sp. nymphs and adults. The results of this study showed pest preference towards different Cyclopia species. As such, they should be managed differently. Furthermore, L. venus was observed to occur in low densities, hence, it cannot be considered a major pest. However, Molopopterus sp. recorded high population densities making it a major pest in Honeybush production. Positive results indicated that some of the isolated fungal isolates have potential for control, an avenue worth investigating further. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mushore, Tapiwa Gift
- Date: 2021-04
- Subjects: Legumes , Legumes -- Diseases and pests , Hepialidae , Leafhoppers , Pests -- Biological control , Entomopathogenic fungi , Leafhoppers -- Biological control , Hepialidae -- Biological control , Keurboom moth (Leto venus Cramer) , Molopopterus sp. Jacobi , Honeybush (Cyclopia spp.)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177125 , vital:42792
- Description: Honeybush, Cyclopia spp. Vent (Fabaceae), farmers have raised pest concerns following commercial cultivation. The Keurboom moth Leto venus Cramer (Lepidoptera: Hepialidae) and the leafhopper Molopopterus sp. Jacobi (Hemiptera: Cicadellidae), are two of the major pests identified in cultivated Honeybush. Laboratory and field studies were conducted to gain an understanding of the biology of these two pests to inform future pest management solutions. Additionally, entomopathogenic fungi were isolated from Honeybush farms and screened for virulence against Molopopterus sp. as a possible management strategy. This study showed that the L. venus infestation on Honeybush was a product of four fixed effects; stem diameter, species of Cyclopia, Farm location and age of the plants. Cyclopia subternata, had the highest likelihood of infestation. Increase in age of the plants resulted in an increase in the stem diameter and therefore a higher probability of infestation. Stem diameter was also shown to be a significant predictor of infestation likelihood. Infestation severity, determined by the number of larvae per plant, was shown to be influenced by three fixed effects; stem diameter, plant species and Farm location. The results also showed that L. venus prefers to initiate penetration at, or just aboveground level. Laboratory studies showed that the leafhopper Molopopterus sp. undergoes five nymphal instars with an average egg incubation time of 20 days, development time from 1st instar to adult of 26 days and average generation time of 47 days. Laboratory experiments revealed variations in host preference by the leafhopper over a period of 15 days. Cyclopia longifolia was identified to be the most preferred species for feeding compared to the two other commonly cultivated species, C. subternata and C. maculata. The results were consistent with those obtained from the field survey which showed that leafhopper density was influenced by four fixed effects; plant species, age of the plant, Farm location and harvesting practices. There were significant differences in leafhopper density in different species with C. longifolia having the highest number of leafhoppers per plant. There were differences in leafhopper density in different farms as 57% of the sampled farms had leafhopper infestations, of these farms, Lodestone and Kurland had the highest leafhopper densities. Harvested plants were shown to have significantly higher leafhopper density than non-harvested plants. Age was also shown to influence leafhopper density, which reduced with an increase in the age of the plants. A total of 20 fungal isolates were recovered from 98 soil samples of which 70% were from Honeybush fields and 30% were from surrounding refugia. Fusarium oxysporum isolates comprised 20% of the recovered isolates, with Metarhizium anisopliae isolates making up the remainder. Laboratory bioassays against adults and nymphs of the leafhopper, Molopopterus sp., showed that F. oxysporum isolates induced 10 – 45% mortality and M. anisopliae isolates induce 30 – 80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both Molopopterus sp. nymphs and adults. The results of this study showed pest preference towards different Cyclopia species. As such, they should be managed differently. Furthermore, L. venus was observed to occur in low densities, hence, it cannot be considered a major pest. However, Molopopterus sp. recorded high population densities making it a major pest in Honeybush production. Positive results indicated that some of the isolated fungal isolates have potential for control, an avenue worth investigating further. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
Characterization of the diversity and metabolic potential of hypolithic communities in dronning Maud Land, Antarctica
- Authors: Mikhari, Rito Leanah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178490 , vital:42944
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mikhari, Rito Leanah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178490 , vital:42944
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
Constraining the role of carbonate assimilation on spinel stability in oxide ores of the Flatreef, Bushveld Complex, South Africa
- Authors: Dyan, Siyasanga
- Date: 2021-04
- Subjects: Oxide minerals -- South Africa -- Bushveld Complex , Transvaal Supergroup (South Africa) , Magmas -- South Africa -- Bushveld Complex , Petrogenesis -- South Africa -- Bushveld Complex , Spinel group – South Africa -- South Africa -- Bushveld Complex , Dolomite -- South Africa -- Bushveld Complex
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174578 , vital:42490
- Description: The northern limb of the Bushveld Complex shows significant evidence for footwall rock- magma interaction, as a result of the emplacement of magmas onto the Transvaal Supergroup sediments. The Platreef of the northern limb is known to have involved extensive contamination of the magma. The lateral extension of the Platreef, the Flatreef, is less contaminated and comprises PGE-mineralization and thick chromitite layers. This enables successful stratigraphic correlation to the Upper Critical Zone of the eastern and western limbs of the Bushveld Complex. This study aims at addressing the influence of dolomitic floor rock contamination on the formation of spinels of the Flatreef and how they may differ to their occurrences in the Bushveld Complex elsewhere. Three main drill cores (UMT-345, UMT-335, and UMT-094) from the deep drilling program by Ivanhoe Mine, north of Turfspruit, were logged and sampled. The drill cores contained rocks contaminated by dolomite in varying degrees, depending on the proportion of carbonate xenoliths present. A total of sixty-two samples were obtained from the UG-2- equivalent chromitite seam, down into the hybrid contaminated units (Footwall Assimilation Zone; FAZ). Petrographic examination of the drill cores revealed that the feldspathic pyroxenite and chromitite layers are the most pristine lithologies in the Flatreef. The chromitite layers occur as a semi-massive to massive ores. The FAZ rocks are mainly dominated by the abundance of Al-rich Cr-spinels (Mg#30-80), clinopyroxenes with a high Ca-Tschermak component (up to 35 mol.%), olivines (Fo72-84), and plagioclase (An31-78). Geochemical characteristics of the feldspathic pyroxenite and chromitite seams include low CaO/Al2O3 and Ca/SiO2 ratios, the low abundance of REE and HFSE. In contrast, the FAZ samples display high CaO/Al2O3 and CaO/SiO2 ratios, suggesting mobilization of CaO-rich fluids derived from the associated dolomite xenoliths. Observations from lithostratigraphic element profiles indicate spikes in CaO within FAZ units relative to the feldspathic pyroxene, indicating a secondary source of CaO linked to proximity to carbonate xenoliths intersected in the core. The assimilation-fractional crystallization model performed with the Upper Critical Zone parental melt and dolomite produced assemblages dominated by spinel, olivine, clinopyroxene, and plagioclase, relating to those of the most contaminated rocks of footwall assimilation zones. The model also showed that large quantities of CO2 were produced during assimilation. High amounts of CO2-fluids mobilized in the melt would have interacted with the melt and increased the overall oxidation conditions. Oxygen fugacity (ƒO2) values were constrained from the spinels in the FAZ and chromites in chromitite seams. Spinels within the most contaminated rocks of the FAZ recorded relatively high ƒO2 values ranging between NNO-0.2 and NNO+1.8 (relative to the Nickel-Nickel-Oxide buffer. High ƒO2 values in spinels from the FAZ suggest that the melt interacted with greater amounts of oxidative CO2-fluids during decarbonation reactions. Such high redox conditions could have triggered the saturation and crystallization of spinels. Comparison of mineral compositions and ƒO2 of UG-2 chromites from the Flatreef with UG-2 from the eastern limb, western limb, chromitites from the Platreef and Uitkomst Complex reveal that Flatreef chromites are of most similar to those of the Platreef Uitkosmt Complex. The northern limb and Uitkomst Complex chromites have high ƒO2 values (NNO+0.3 to NNO+1.2), indicating their apparent link to the Malmani dolomite. Interaction of magma with the Malmani dolomite would have produced high quantities of CO2, triggering an increase in oxidizing conditions. Such an effect is most prominent in the Flatreef chromitites that are in contact with the FAZ. The chromites are characterised by high ƒO2 (NNO+1.2) and distinct compositions (low Cr2O3, high Fe3+/Fetotal, and TiO2). Thus, it is proposed that carbonate assimilation in the Flatreef triggered the precipitation of these distinctive chromites proximal to FAZ, due to liberation of substantial amounts of CO2-rich fluids with a highly oxidative capacity. Carbonate assimilation in layered intrusions can be used as a monitor potential precipitation of chromites. , Thesis (MSc)--Rhodes University, Faculty of Science, Department of Geology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Dyan, Siyasanga
- Date: 2021-04
- Subjects: Oxide minerals -- South Africa -- Bushveld Complex , Transvaal Supergroup (South Africa) , Magmas -- South Africa -- Bushveld Complex , Petrogenesis -- South Africa -- Bushveld Complex , Spinel group – South Africa -- South Africa -- Bushveld Complex , Dolomite -- South Africa -- Bushveld Complex
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174578 , vital:42490
- Description: The northern limb of the Bushveld Complex shows significant evidence for footwall rock- magma interaction, as a result of the emplacement of magmas onto the Transvaal Supergroup sediments. The Platreef of the northern limb is known to have involved extensive contamination of the magma. The lateral extension of the Platreef, the Flatreef, is less contaminated and comprises PGE-mineralization and thick chromitite layers. This enables successful stratigraphic correlation to the Upper Critical Zone of the eastern and western limbs of the Bushveld Complex. This study aims at addressing the influence of dolomitic floor rock contamination on the formation of spinels of the Flatreef and how they may differ to their occurrences in the Bushveld Complex elsewhere. Three main drill cores (UMT-345, UMT-335, and UMT-094) from the deep drilling program by Ivanhoe Mine, north of Turfspruit, were logged and sampled. The drill cores contained rocks contaminated by dolomite in varying degrees, depending on the proportion of carbonate xenoliths present. A total of sixty-two samples were obtained from the UG-2- equivalent chromitite seam, down into the hybrid contaminated units (Footwall Assimilation Zone; FAZ). Petrographic examination of the drill cores revealed that the feldspathic pyroxenite and chromitite layers are the most pristine lithologies in the Flatreef. The chromitite layers occur as a semi-massive to massive ores. The FAZ rocks are mainly dominated by the abundance of Al-rich Cr-spinels (Mg#30-80), clinopyroxenes with a high Ca-Tschermak component (up to 35 mol.%), olivines (Fo72-84), and plagioclase (An31-78). Geochemical characteristics of the feldspathic pyroxenite and chromitite seams include low CaO/Al2O3 and Ca/SiO2 ratios, the low abundance of REE and HFSE. In contrast, the FAZ samples display high CaO/Al2O3 and CaO/SiO2 ratios, suggesting mobilization of CaO-rich fluids derived from the associated dolomite xenoliths. Observations from lithostratigraphic element profiles indicate spikes in CaO within FAZ units relative to the feldspathic pyroxene, indicating a secondary source of CaO linked to proximity to carbonate xenoliths intersected in the core. The assimilation-fractional crystallization model performed with the Upper Critical Zone parental melt and dolomite produced assemblages dominated by spinel, olivine, clinopyroxene, and plagioclase, relating to those of the most contaminated rocks of footwall assimilation zones. The model also showed that large quantities of CO2 were produced during assimilation. High amounts of CO2-fluids mobilized in the melt would have interacted with the melt and increased the overall oxidation conditions. Oxygen fugacity (ƒO2) values were constrained from the spinels in the FAZ and chromites in chromitite seams. Spinels within the most contaminated rocks of the FAZ recorded relatively high ƒO2 values ranging between NNO-0.2 and NNO+1.8 (relative to the Nickel-Nickel-Oxide buffer. High ƒO2 values in spinels from the FAZ suggest that the melt interacted with greater amounts of oxidative CO2-fluids during decarbonation reactions. Such high redox conditions could have triggered the saturation and crystallization of spinels. Comparison of mineral compositions and ƒO2 of UG-2 chromites from the Flatreef with UG-2 from the eastern limb, western limb, chromitites from the Platreef and Uitkomst Complex reveal that Flatreef chromites are of most similar to those of the Platreef Uitkosmt Complex. The northern limb and Uitkomst Complex chromites have high ƒO2 values (NNO+0.3 to NNO+1.2), indicating their apparent link to the Malmani dolomite. Interaction of magma with the Malmani dolomite would have produced high quantities of CO2, triggering an increase in oxidizing conditions. Such an effect is most prominent in the Flatreef chromitites that are in contact with the FAZ. The chromites are characterised by high ƒO2 (NNO+1.2) and distinct compositions (low Cr2O3, high Fe3+/Fetotal, and TiO2). Thus, it is proposed that carbonate assimilation in the Flatreef triggered the precipitation of these distinctive chromites proximal to FAZ, due to liberation of substantial amounts of CO2-rich fluids with a highly oxidative capacity. Carbonate assimilation in layered intrusions can be used as a monitor potential precipitation of chromites. , Thesis (MSc)--Rhodes University, Faculty of Science, Department of Geology, 2021
- Full Text:
- Date Issued: 2021-04
Detection and effects of selected pharmaceutical compounds from selected water bodies in the Eastern Cape Province, South Africa
- Authors: Setshedi, Koketso Josinah
- Date: 2021-04
- Subjects: Antimicrobial resistance , Drugs , Waterborne infection , Water quality South Africa Eastern Cape , Climatic changes South Africa , Wastewater treatment
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489222 , vital:80169
- Description: Water is significantly essential of all-natural assets recognized over the earth. It is necessary to biota, mostly ecosystem, public health, food processing, and economic sustainability. The protection of potable water is crucial for health. Several pollutants that are made up of chemical and microbiological substances affect drinking water. Those pollutants create severe medical challenges, and as a result, the quality of water turns out to be inadequate. Frequently unsatisfactory quality of water induces various health problems in people. Therefore, water quality needs to be tested chemically and microbiologically. This thesis focuses on the prevalence of pharmaceutical products from the rivers (streams) and wastewater treatment plants found along the rivers of Makhanda, Alice, and King William's Town. The physical and chemical parameters were as follows: Temperature ranged from 9.97 to 22.03 °C, pH from 4.32 to 10.60, turbidity from 4.63 to 318 NTU, electrical conductivity from 8.70 to 381.27 mS/m, nitrate from not detected to 100 mg/L, chemical oxygen demand from 5.33 to 296 mg/L, dissolved oxygen from 2.43 to 7.70 mg/L, chloride from not detected to 180.67 mg/L, phosphate from not detected to 0.55 mg/L and sulfate from not detected to 193 mg/L. The results indicate that turbidity, sulfate, and EC adversely affect surface water sources; high concentrations of such parameters verify that further studies are necessary. Hence, some of them do not cause detrimental effects on human health. High levels were principally in rainy seasons, which could have resulted from contaminants' washout from point source pollution into surface water in rains. Other parameters overstepped the acceptable ranges of the Target Water Quality Range, World Health Organisation, and South African National Standard guidelines in some investigation regions. Water samples were freeze-dried to prepare solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometer to identify composites. Levonorgestrel and ethinylestradiol were not detected throughout the water samples. Four antiretroviral drugs were detected: Lopinavir ranged from not detected to 1141.8 ng/L, Emtricitabine from not detected to 18757.4 ng/L, Nevirapine from not detected to 10047.2 ng/L, and Efavirenz from 40.6 to 55844.6 ng/L. The bacterial colonies ranged from 1.07E +06 to 9.70E +05 CFU/mL in Makhanda region, 1.03E +04 to 7.93E +04 CFU/mL in Alice region and 1.08E +05 to 9.33E +05 CFU/mL in King William’s Town region. Analytical profile index 20E system identified Shigella spp as the most dominant at 81.5% identity. Furthermore, identified Chromobacterium violaceum, Pasteurella pneumotropica, and Pneumonia ssp rhinosceromatis at 97.7 %, 75.1%, and 69% identity. Antibiotic susceptibility testing has shown that Ciprofloxacin was susceptible in all water sample sites except for the lower stream of Tyhume River. Amoxicillin has shown resistance to many parts of the water sample sites. The 16S rRNA (DNA) gene sequencing detected microorganisms in water samples. Firmicutes were the most dominant phylum with high abundance in all water samples. Phyla Firmicutes and Bacteriodota have proven that they can survive in wastewater treatment plants. Entirely, this survey reveals that water is potentially unsafe for consumers' health and stresses the need to treat the wastewater treatment plants and support maintainable farming methods for preventing detrimental health damages. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Setshedi, Koketso Josinah
- Date: 2021-04
- Subjects: Antimicrobial resistance , Drugs , Waterborne infection , Water quality South Africa Eastern Cape , Climatic changes South Africa , Wastewater treatment
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489222 , vital:80169
- Description: Water is significantly essential of all-natural assets recognized over the earth. It is necessary to biota, mostly ecosystem, public health, food processing, and economic sustainability. The protection of potable water is crucial for health. Several pollutants that are made up of chemical and microbiological substances affect drinking water. Those pollutants create severe medical challenges, and as a result, the quality of water turns out to be inadequate. Frequently unsatisfactory quality of water induces various health problems in people. Therefore, water quality needs to be tested chemically and microbiologically. This thesis focuses on the prevalence of pharmaceutical products from the rivers (streams) and wastewater treatment plants found along the rivers of Makhanda, Alice, and King William's Town. The physical and chemical parameters were as follows: Temperature ranged from 9.97 to 22.03 °C, pH from 4.32 to 10.60, turbidity from 4.63 to 318 NTU, electrical conductivity from 8.70 to 381.27 mS/m, nitrate from not detected to 100 mg/L, chemical oxygen demand from 5.33 to 296 mg/L, dissolved oxygen from 2.43 to 7.70 mg/L, chloride from not detected to 180.67 mg/L, phosphate from not detected to 0.55 mg/L and sulfate from not detected to 193 mg/L. The results indicate that turbidity, sulfate, and EC adversely affect surface water sources; high concentrations of such parameters verify that further studies are necessary. Hence, some of them do not cause detrimental effects on human health. High levels were principally in rainy seasons, which could have resulted from contaminants' washout from point source pollution into surface water in rains. Other parameters overstepped the acceptable ranges of the Target Water Quality Range, World Health Organisation, and South African National Standard guidelines in some investigation regions. Water samples were freeze-dried to prepare solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometer to identify composites. Levonorgestrel and ethinylestradiol were not detected throughout the water samples. Four antiretroviral drugs were detected: Lopinavir ranged from not detected to 1141.8 ng/L, Emtricitabine from not detected to 18757.4 ng/L, Nevirapine from not detected to 10047.2 ng/L, and Efavirenz from 40.6 to 55844.6 ng/L. The bacterial colonies ranged from 1.07E +06 to 9.70E +05 CFU/mL in Makhanda region, 1.03E +04 to 7.93E +04 CFU/mL in Alice region and 1.08E +05 to 9.33E +05 CFU/mL in King William’s Town region. Analytical profile index 20E system identified Shigella spp as the most dominant at 81.5% identity. Furthermore, identified Chromobacterium violaceum, Pasteurella pneumotropica, and Pneumonia ssp rhinosceromatis at 97.7 %, 75.1%, and 69% identity. Antibiotic susceptibility testing has shown that Ciprofloxacin was susceptible in all water sample sites except for the lower stream of Tyhume River. Amoxicillin has shown resistance to many parts of the water sample sites. The 16S rRNA (DNA) gene sequencing detected microorganisms in water samples. Firmicutes were the most dominant phylum with high abundance in all water samples. Phyla Firmicutes and Bacteriodota have proven that they can survive in wastewater treatment plants. Entirely, this survey reveals that water is potentially unsafe for consumers' health and stresses the need to treat the wastewater treatment plants and support maintainable farming methods for preventing detrimental health damages. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Development and assessment of rifampicin loaded self-microemulsifying drug delivery systems
- Authors: Mphaphuli, Mashudu Theodore
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178503 , vital:42945
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mphaphuli, Mashudu Theodore
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178503 , vital:42945
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Development and characterisation of ciprofloxacin hydrochloride solid lipid nanoparticles for ocular delivery
- Authors: Dhege, Clarence
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178446 , vital:42940
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Dhege, Clarence
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178446 , vital:42940
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Does the Transkei population of Haliotis Midae at the eastern edge of its distributional range have a higher thermal tolerance than those in more temperate waters?
- Authors: Mathebula, Surprise
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa -- Indian Coast , Abalones -- South Africa -- Indian Coast , Haliotis midae -- Effect of temperature on -- South Africa -- Indian Coast , Haliotis midae -- Physiology -- South Africa -- Indian Coast , Haliotis midae -- Adaptation -- South Africa -- Indian Coast , Haliotis midae -- Growth -- South Africa -- Indian Coast
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177360 , vital:42814
- Description: The South African perlemoen abalone (Haliotis midae) may be vulnerable to rising temperatures on the East coast of South Africa due to climate change. H. midae is South Africa’s most valuable aquaculture species, and it is thus important to understand its physiological ability to adapt to the expected changes and to identify possible management measures to mitigate the impacts of rising temperatures. This project aimed to understand thermal tolerance and growth rates of offspring from two H. midae populations originating from the warm-temperate Central region (Port Elizabeth) and warmer Eastern edge of the species’ distribution in the Transkei region. To determine the effects of temperature on the physiological performance of the two abalone populations, growth rates, oxygen consumption rates and critical thermal maxima (CTM) were compared. A laboratory growth trial was conducted at three controlled temperatures, visibly, the ‘optimal’ temperature for H. midae growth (18 - 20℃), ‘pejus’ (stressful) temperature (21 - 22℃) and ‘critical’ temperature (23 - 24℃). Oxygen consumption rates were recorded at optimum (20℃), pejus (22℃) and critical (24℃) temperature using a respirometer. In addition, a farm growth trial with simultaneously spawned cohorts of abalone from the two populations was conducted at ambient temperature (19.5 and 20.0℃). The laboratory growth trial revealed no significant differences in growth rate between the two populations at the three temperature treatments (ANOVA, P > 0.05; df = 2). However, mortalities were high and growth rates low, indicating that the rearing conditions were sub-optimal, possibly masking genetic differences. No significant differences were observed in oxygen consumption rates (ANOVA, P = 0.18; df = 2), and CTM (t-Test, P = 0.31; df = 3) between the two populations. The CTM for both populations was between 29 - 30℃. The farm trial yielded no significant differences in growth rate during the Nursery phase (t-Test, P = 0.25; df = 2), however significant differences in growth rate were observed during the grow out phase with the Central region abalone offspring growing faster than the Eastern edge population (t-Test, P = 0.04; df = 4) indicating the possibility of a genetic difference between the two populations. Further experiments will be required to determine whether the differences observed in the growth trial were genetically or environmentally induced. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mathebula, Surprise
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa -- Indian Coast , Abalones -- South Africa -- Indian Coast , Haliotis midae -- Effect of temperature on -- South Africa -- Indian Coast , Haliotis midae -- Physiology -- South Africa -- Indian Coast , Haliotis midae -- Adaptation -- South Africa -- Indian Coast , Haliotis midae -- Growth -- South Africa -- Indian Coast
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177360 , vital:42814
- Description: The South African perlemoen abalone (Haliotis midae) may be vulnerable to rising temperatures on the East coast of South Africa due to climate change. H. midae is South Africa’s most valuable aquaculture species, and it is thus important to understand its physiological ability to adapt to the expected changes and to identify possible management measures to mitigate the impacts of rising temperatures. This project aimed to understand thermal tolerance and growth rates of offspring from two H. midae populations originating from the warm-temperate Central region (Port Elizabeth) and warmer Eastern edge of the species’ distribution in the Transkei region. To determine the effects of temperature on the physiological performance of the two abalone populations, growth rates, oxygen consumption rates and critical thermal maxima (CTM) were compared. A laboratory growth trial was conducted at three controlled temperatures, visibly, the ‘optimal’ temperature for H. midae growth (18 - 20℃), ‘pejus’ (stressful) temperature (21 - 22℃) and ‘critical’ temperature (23 - 24℃). Oxygen consumption rates were recorded at optimum (20℃), pejus (22℃) and critical (24℃) temperature using a respirometer. In addition, a farm growth trial with simultaneously spawned cohorts of abalone from the two populations was conducted at ambient temperature (19.5 and 20.0℃). The laboratory growth trial revealed no significant differences in growth rate between the two populations at the three temperature treatments (ANOVA, P > 0.05; df = 2). However, mortalities were high and growth rates low, indicating that the rearing conditions were sub-optimal, possibly masking genetic differences. No significant differences were observed in oxygen consumption rates (ANOVA, P = 0.18; df = 2), and CTM (t-Test, P = 0.31; df = 3) between the two populations. The CTM for both populations was between 29 - 30℃. The farm trial yielded no significant differences in growth rate during the Nursery phase (t-Test, P = 0.25; df = 2), however significant differences in growth rate were observed during the grow out phase with the Central region abalone offspring growing faster than the Eastern edge population (t-Test, P = 0.04; df = 4) indicating the possibility of a genetic difference between the two populations. Further experiments will be required to determine whether the differences observed in the growth trial were genetically or environmentally induced. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
Effects of organic and inorganic pollutants on the quality of river water and evaluation of possible negative effects on human health in the Eastern Cape Province
- Authors: Vumazonke, Sesethu
- Date: 2021-04
- Subjects: Water Pollution South Africa Eastern Cape , Water quality South Africa Eastern Cape , Physicochemical process , Drug resistance in microorganisms , Aquatic invertebrates
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489233 , vital:80170
- Description: The quality of river water has been gradually decreasing for the past years due to pollution by faecal pathogens, organic and inorganic contaminants. This has caused environmental concern which led to the creation of a large area of research in many countries. In this study, the quality of river water was monitored by measuring physicochemical properties, bacteriological quality, screening of pharmaceuticals and biomonitoring water quality using aquatic macroinvertebrates. The physical parameters indicated the following; chemical oxygen demand ranged from 6 to 45 mg/L, turbidity ranged from 0.00 to 718 NTU, pH ranged from 5.89 to 9.77 and electric conductivity ranged from 0.00 to 2.95 mS. The concentrations of chemical parameters included phosphate ranged from 0.00 to 16 mg/L, chloride ranged from 80 to 518 mg/L, ammonium ranged from 5 to 279 mg/L, nitrate ranged from 0 to 50 mg/L, nitrite ranged from negative to positive, iron concentration was 0 mg/L in all the rivers throughout the sampling seasons while sulphate ranged from 5 to 103 mg/L. The bacteriological quality of river water ranged as follows; total coliform ranged from 0.20 to 255682 cfu/100 mL, faecal coliform ranged from 0.02 to 1091 cfu/100 mL and heterotrophic bacteria ranged from 213 to 1153543 cfu/mL. Several bacterial species were identified with analytical profile index kit with Klebsiella oxytoca, Vibrio alginolyticus, Providencia stuartii, Ewingella Americana, Providencia alcalifaciens/ rustigianii, Enterobacter cloacae, Leclercia adecarboxylata, Proteus penneri, Aeromonas salmonicida ssp salmonicida and Escherichia coli being the most dominant pathogenic bacteria present in the rivers. Pharmaceuticals screening was conducted using enzyme-linked immunoassay kits with fluoroquinolones detected in a concentration range of lower than detectable limits (LDL) to 0.4 ppb while sulfamethoxazole was in a concentration range of LDL to 1.4 ppb. Pre-concentration and extraction of the target pharmaceuticals in water samples were conducted by lyophilization followed by solid-phase extraction on Water Oasis HLB cartridge and ultra-performance liquid chromatography- electron spray ionization tandem mass spectrometry was used for detection of the compounds. The antibiotics detected were sulfamethoxazole at a concentration range of LDL to 3484 ng/0.5 L, clarithromycin at 2.4 to 1640.2 ng/0.5 L and erythromycin at LDL to 372.1 μg/0.5 L and anti-epilepsy drug detected was carbamazepine at a concentration of 40.9 to 18288.1 ng/0.5 L in river water samples. Ibuprofen and ciprofloxacin were not detected. The biological quality of river water was assessed using aquatic macroinvertebrates. The presence of highly sensitive families such as Heptageniidae, Crambidae and Glossosomatidae was a confirmation that the quality of river water was in a good state on upper stream sites, while middle stream and lower stream sites were impacted. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Vumazonke, Sesethu
- Date: 2021-04
- Subjects: Water Pollution South Africa Eastern Cape , Water quality South Africa Eastern Cape , Physicochemical process , Drug resistance in microorganisms , Aquatic invertebrates
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489233 , vital:80170
- Description: The quality of river water has been gradually decreasing for the past years due to pollution by faecal pathogens, organic and inorganic contaminants. This has caused environmental concern which led to the creation of a large area of research in many countries. In this study, the quality of river water was monitored by measuring physicochemical properties, bacteriological quality, screening of pharmaceuticals and biomonitoring water quality using aquatic macroinvertebrates. The physical parameters indicated the following; chemical oxygen demand ranged from 6 to 45 mg/L, turbidity ranged from 0.00 to 718 NTU, pH ranged from 5.89 to 9.77 and electric conductivity ranged from 0.00 to 2.95 mS. The concentrations of chemical parameters included phosphate ranged from 0.00 to 16 mg/L, chloride ranged from 80 to 518 mg/L, ammonium ranged from 5 to 279 mg/L, nitrate ranged from 0 to 50 mg/L, nitrite ranged from negative to positive, iron concentration was 0 mg/L in all the rivers throughout the sampling seasons while sulphate ranged from 5 to 103 mg/L. The bacteriological quality of river water ranged as follows; total coliform ranged from 0.20 to 255682 cfu/100 mL, faecal coliform ranged from 0.02 to 1091 cfu/100 mL and heterotrophic bacteria ranged from 213 to 1153543 cfu/mL. Several bacterial species were identified with analytical profile index kit with Klebsiella oxytoca, Vibrio alginolyticus, Providencia stuartii, Ewingella Americana, Providencia alcalifaciens/ rustigianii, Enterobacter cloacae, Leclercia adecarboxylata, Proteus penneri, Aeromonas salmonicida ssp salmonicida and Escherichia coli being the most dominant pathogenic bacteria present in the rivers. Pharmaceuticals screening was conducted using enzyme-linked immunoassay kits with fluoroquinolones detected in a concentration range of lower than detectable limits (LDL) to 0.4 ppb while sulfamethoxazole was in a concentration range of LDL to 1.4 ppb. Pre-concentration and extraction of the target pharmaceuticals in water samples were conducted by lyophilization followed by solid-phase extraction on Water Oasis HLB cartridge and ultra-performance liquid chromatography- electron spray ionization tandem mass spectrometry was used for detection of the compounds. The antibiotics detected were sulfamethoxazole at a concentration range of LDL to 3484 ng/0.5 L, clarithromycin at 2.4 to 1640.2 ng/0.5 L and erythromycin at LDL to 372.1 μg/0.5 L and anti-epilepsy drug detected was carbamazepine at a concentration of 40.9 to 18288.1 ng/0.5 L in river water samples. Ibuprofen and ciprofloxacin were not detected. The biological quality of river water was assessed using aquatic macroinvertebrates. The presence of highly sensitive families such as Heptageniidae, Crambidae and Glossosomatidae was a confirmation that the quality of river water was in a good state on upper stream sites, while middle stream and lower stream sites were impacted. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Evaluation of water quality, selected metals and endocrine-disrupting compounds in the rivers and municipal wastewaters of Eastern Cape Province, South africa
- Authors: Farounbi, Adebayo Ibikunle
- Date: 2021-04
- Subjects: Water Pollution South Africa Eastern Cape , Wastewater treatment , Endocrine disrupting chemicals , Heavy metals , Mass spectrometry , Physicochemical process , Nuclear magnetic resonance , Infrared spectroscopy
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489244 , vital:80173
- Description: South Africa is developing with increasing population, and so is the demand for use and access to water resources. Surface water is critical to the country because it provides about 77% of the needed water resources. Low rainfall (about 450 mm annually) with little runoffs to boost the rivers aggravates the problems of surface waters. Expansion of industrial and agricultural activities coupled with the population pressure had an impact on water quality, availability and the state of aquatic ecosystems in the country. Water management is a challenge in South Africa because of the socio-economic pressure and other factors such as mine wastewater, eutrophication, salinisation, and emerging contaminants. This research investigated some water quality parameters of Bloukrans, Buffalo, Swartkops and Tyhume Rivers in Eastern Cape Province of South Africa for three seasons. The parameters investigated include the physicochemical properties, functional groups of organic compounds, presence of endocrine-disrupting compounds and heavy metals in the rivers and wastewater effluents from wastewater treatment plants (WWTPs) released into these rivers. The aims were to determine the concentrations of these parameters in the rivers and wastewater effluents, compare the concentration levels with recommended values for aquatic lives, domestic and agricultural purposes, thereby contributing to the effective management of water in South Africa. Water samples were collected for analyses at upstream, midstream and downstream reaches of the rivers. In contrast, wastewater influent and effluent samples were obtained from wastewater treatment plants releasing effluents to the rivers. Some physicochemical parameters were studied onsite with specialised meters while others analysed in the laboratory with ultraviolet (UV) spectroscopy. Chemical functional groups in the samples were determined with Fourier-transformed infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies. The Endocrine-disrupting compounds and heavy metals were determined with liquid chromatography coupled to a mass spectrometer (LC-MS/MS) and inductively coupled plasma with a mass spectrometer (ICP-MS) respectively. Method validation and calibration for all the spectrometry yielded good linearity (r2 > 0.99). The results showed high oxygen demand above the concentration recommended by the South Africa Department of water affairs and forestry (DWAF) for Alice and Uitenhage wastewater effluents, midstream and downstream river samples. Phosphate concentrations were higher than the recommended level in wastewater effluents. Sulphate rivers at midstream and downstream reaches were higher than 8.0 except in Bloukrans River, where it was around 7.0. The functional group analyses show the presence of substituted aromatic compounds, alkyl halides, chlorobenzenes, vinylidenes, amides, amines, urethanes, cycloalkanes, acetonitriles, methenamine, imidazole and phenolic compounds among others, in the samples. The presence of these functional groups in the water samples is an indication of pollution by volatile organic compounds, persistent organic pollutants and pharmaceuticals. Results of LC-MS/MS analysis show that endocrine-disrupting compounds (EDCs) were present in the rivers and wastewaters samples. Descriptive statistics showed the mean concentrations of the EDCs in the samples as nonylphenol > dichlorophenol > bisphenol A > triclosan > octylphenol > imidazole > atrazine > triazole > estrone > estradiol. The results of the heavy metal analysis show that chromium had the highest mean concentration in the samples. The mean metals concentrations in the samples were in the order of Cr > Ni > Mn > Cu > As > Pb > Cd > Hg > Zn. The results showed an increase in the concentrations of metals in the rivers over the years. The chromium, manganese, nickel, copper, zinc, arsenic, cadmium, lead and mercury concentrations in the lower reaches of the rivers and wastewater effluents were higher than the values recommended by the United Nations Environmental Programme (UNEP) and DWAF. Improvement is necessary in wastewater treatment and adequate legislation on chemical usage. Some chemicals banned in developed countries, such as atrazine, were encountered in this study. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Farounbi, Adebayo Ibikunle
- Date: 2021-04
- Subjects: Water Pollution South Africa Eastern Cape , Wastewater treatment , Endocrine disrupting chemicals , Heavy metals , Mass spectrometry , Physicochemical process , Nuclear magnetic resonance , Infrared spectroscopy
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/489244 , vital:80173
- Description: South Africa is developing with increasing population, and so is the demand for use and access to water resources. Surface water is critical to the country because it provides about 77% of the needed water resources. Low rainfall (about 450 mm annually) with little runoffs to boost the rivers aggravates the problems of surface waters. Expansion of industrial and agricultural activities coupled with the population pressure had an impact on water quality, availability and the state of aquatic ecosystems in the country. Water management is a challenge in South Africa because of the socio-economic pressure and other factors such as mine wastewater, eutrophication, salinisation, and emerging contaminants. This research investigated some water quality parameters of Bloukrans, Buffalo, Swartkops and Tyhume Rivers in Eastern Cape Province of South Africa for three seasons. The parameters investigated include the physicochemical properties, functional groups of organic compounds, presence of endocrine-disrupting compounds and heavy metals in the rivers and wastewater effluents from wastewater treatment plants (WWTPs) released into these rivers. The aims were to determine the concentrations of these parameters in the rivers and wastewater effluents, compare the concentration levels with recommended values for aquatic lives, domestic and agricultural purposes, thereby contributing to the effective management of water in South Africa. Water samples were collected for analyses at upstream, midstream and downstream reaches of the rivers. In contrast, wastewater influent and effluent samples were obtained from wastewater treatment plants releasing effluents to the rivers. Some physicochemical parameters were studied onsite with specialised meters while others analysed in the laboratory with ultraviolet (UV) spectroscopy. Chemical functional groups in the samples were determined with Fourier-transformed infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies. The Endocrine-disrupting compounds and heavy metals were determined with liquid chromatography coupled to a mass spectrometer (LC-MS/MS) and inductively coupled plasma with a mass spectrometer (ICP-MS) respectively. Method validation and calibration for all the spectrometry yielded good linearity (r2 > 0.99). The results showed high oxygen demand above the concentration recommended by the South Africa Department of water affairs and forestry (DWAF) for Alice and Uitenhage wastewater effluents, midstream and downstream river samples. Phosphate concentrations were higher than the recommended level in wastewater effluents. Sulphate rivers at midstream and downstream reaches were higher than 8.0 except in Bloukrans River, where it was around 7.0. The functional group analyses show the presence of substituted aromatic compounds, alkyl halides, chlorobenzenes, vinylidenes, amides, amines, urethanes, cycloalkanes, acetonitriles, methenamine, imidazole and phenolic compounds among others, in the samples. The presence of these functional groups in the water samples is an indication of pollution by volatile organic compounds, persistent organic pollutants and pharmaceuticals. Results of LC-MS/MS analysis show that endocrine-disrupting compounds (EDCs) were present in the rivers and wastewaters samples. Descriptive statistics showed the mean concentrations of the EDCs in the samples as nonylphenol > dichlorophenol > bisphenol A > triclosan > octylphenol > imidazole > atrazine > triazole > estrone > estradiol. The results of the heavy metal analysis show that chromium had the highest mean concentration in the samples. The mean metals concentrations in the samples were in the order of Cr > Ni > Mn > Cu > As > Pb > Cd > Hg > Zn. The results showed an increase in the concentrations of metals in the rivers over the years. The chromium, manganese, nickel, copper, zinc, arsenic, cadmium, lead and mercury concentrations in the lower reaches of the rivers and wastewater effluents were higher than the values recommended by the United Nations Environmental Programme (UNEP) and DWAF. Improvement is necessary in wastewater treatment and adequate legislation on chemical usage. Some chemicals banned in developed countries, such as atrazine, were encountered in this study. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Healthcare issues in disaster management : preparedness in the pharmacy profession
- Authors: Vhiriri, Eunice Paidamoyo
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178591 , vital:42953
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Vhiriri, Eunice Paidamoyo
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178591 , vital:42953
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
In silico identification of selective novel hits against the active site of wild type mycobacterium tuberculosis pyrazinamidase and its mutants
- Authors: Gowo, Prudence
- Date: 2021-04
- Subjects: Mycobacterium tuberculosis , Pyrazinamide , Multidrug resistance , Antitubercular agents , Molecular dynamics , Hydrogen bonding , Ligand binding (Biochemistry) , Dynamic Residue Network
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178007 , vital:42898
- Description: The World Health Organization declared Tuberculosis a global health emergency and has set a goal to eradicate it by 2035. However, effective treatment and control of the disease is being hindered by the emerging Multi-Drug Resistant and Extensively Drug Resistant strains on the most effective first line prodrug, Pyrazinamide (PZA). Studies have shown that the main cause of PZA resistance is due to mutations in the pncA gene that codes for the target protein Pyrazinamidase (PZase). Therefore, this study aimed to identify novel drug compounds that bind to the active site of wild type PZase and study the dynamics of these potential anti-TB drugs in the mutant systems of PZase. This approach will aid in identifying drugs that may be repurposed for TB therapy and/or designed to counteract PZA resistance. This was achieved by screening 2089 DrugBank compounds against the whole wild type (WT) PZase protein in molecular docking using AutoDOCK4.2. Compound screening based on docking binding energy, hydrogen bonds, molecular weight and active site proximity identified 47 compounds meeting all the set selection criteria. The stability of these compounds were analysed in Molecular Dynamic (MD) simulations and were further studied in PZase mutant systems of A3P, A134V, A146V, D8G, D49A, D49G, D63G, H51P, H137R, L85R, L116R, Q10P, R140S, T61P, V139M and Y103S. Generally, mutant-ligand systems displayed little deviation from the WT systems. The compound systems remained compact, with less fluctuations and more hydrogen bond interactions throughout the simulation (DB00255, DB00655, DB00672, DB00782, DB00977, DB01196, DB04573, DB06414, DB08981, DB11181, DB11760, DB13867, DB13952). From this research study, potential drugs that may be repurposed for TB therapy were identified. Majority of these drugs are currently used in the treatment of hypertension, menopause disorders and inflammation. To further understand the mutant-ligand dynamic systems, calculations such as Dynamic Residue Network (DRN) may be done. Also, the bioactivity of these drugs on Mycobacterium tuberculosis may be studied in wet laboratory, to understand their clinical impart in vivo experiments. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Gowo, Prudence
- Date: 2021-04
- Subjects: Mycobacterium tuberculosis , Pyrazinamide , Multidrug resistance , Antitubercular agents , Molecular dynamics , Hydrogen bonding , Ligand binding (Biochemistry) , Dynamic Residue Network
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178007 , vital:42898
- Description: The World Health Organization declared Tuberculosis a global health emergency and has set a goal to eradicate it by 2035. However, effective treatment and control of the disease is being hindered by the emerging Multi-Drug Resistant and Extensively Drug Resistant strains on the most effective first line prodrug, Pyrazinamide (PZA). Studies have shown that the main cause of PZA resistance is due to mutations in the pncA gene that codes for the target protein Pyrazinamidase (PZase). Therefore, this study aimed to identify novel drug compounds that bind to the active site of wild type PZase and study the dynamics of these potential anti-TB drugs in the mutant systems of PZase. This approach will aid in identifying drugs that may be repurposed for TB therapy and/or designed to counteract PZA resistance. This was achieved by screening 2089 DrugBank compounds against the whole wild type (WT) PZase protein in molecular docking using AutoDOCK4.2. Compound screening based on docking binding energy, hydrogen bonds, molecular weight and active site proximity identified 47 compounds meeting all the set selection criteria. The stability of these compounds were analysed in Molecular Dynamic (MD) simulations and were further studied in PZase mutant systems of A3P, A134V, A146V, D8G, D49A, D49G, D63G, H51P, H137R, L85R, L116R, Q10P, R140S, T61P, V139M and Y103S. Generally, mutant-ligand systems displayed little deviation from the WT systems. The compound systems remained compact, with less fluctuations and more hydrogen bond interactions throughout the simulation (DB00255, DB00655, DB00672, DB00782, DB00977, DB01196, DB04573, DB06414, DB08981, DB11181, DB11760, DB13867, DB13952). From this research study, potential drugs that may be repurposed for TB therapy were identified. Majority of these drugs are currently used in the treatment of hypertension, menopause disorders and inflammation. To further understand the mutant-ligand dynamic systems, calculations such as Dynamic Residue Network (DRN) may be done. Also, the bioactivity of these drugs on Mycobacterium tuberculosis may be studied in wet laboratory, to understand their clinical impart in vivo experiments. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04