The reading to learn pedagogy in South African inclusive English First Additional Language classrooms: successes and challenges
- Authors: Moyo, Sheron
- Date: 2024-10-11
- Subjects: Reading (Secondary) South Africa Northern Cape , Reading comprehension , English as a second or foreign language , Inclusive education South Africa Northern Cape , High school students Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463735 , vital:76436
- Description: Reading to Learn (RtL) has been frequently suggested for students not meeting grade-appropriate reading standards. However, its achievements and shortcomings have not been examined in inclusive education. In light of this, the main goal of this study was to explore the successes and challenges of this methodology in grade 9 English First Additional Language (FAL) inclusive classrooms across four schools in the Northern Cape Province’s John Taolo Gaetsewe District. In light of the grave concerns about literacy development in South African schools, this methodology was created to fulfil the literacy needs of students from underprivileged groups in Australia. This qualitative study was grounded in social constructivist theory and an interpretative paradigm. The research used an exploratory case study comprising four participants who were purposively recruited and empowered with RtL between 2016 and 2022. The data-gathering methods used were semi-structured interviews, focus group discussions, and classroom observations to get insights into the achievements and shortcomings of the RtL pedagogy in inclusive classrooms. The qualitative data in this study was analysed using thematic analysis. The study’s findings revealed that the RtL pedagogy gave students who faced reading obstacles in inclusive classes the skills needed to read, read with meaning, and improve as readers and writers through its six-step scaffolding interactive cycle. There were challenges in employing the RtL pedagogy in inclusive classes, such as it is time-consuming and makes it difficult for teachers to adhere to the time frame stipulated by the annual teaching plan. Nevertheless, the study’s findings showed that the advantages of the RtL pedagogy outweigh the challenges. , Thesis (MEd) -- Faculty of Education, Institute for the Study of Englishes of Africa, 2024
- Full Text:
- Authors: Moyo, Sheron
- Date: 2024-10-11
- Subjects: Reading (Secondary) South Africa Northern Cape , Reading comprehension , English as a second or foreign language , Inclusive education South Africa Northern Cape , High school students Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463735 , vital:76436
- Description: Reading to Learn (RtL) has been frequently suggested for students not meeting grade-appropriate reading standards. However, its achievements and shortcomings have not been examined in inclusive education. In light of this, the main goal of this study was to explore the successes and challenges of this methodology in grade 9 English First Additional Language (FAL) inclusive classrooms across four schools in the Northern Cape Province’s John Taolo Gaetsewe District. In light of the grave concerns about literacy development in South African schools, this methodology was created to fulfil the literacy needs of students from underprivileged groups in Australia. This qualitative study was grounded in social constructivist theory and an interpretative paradigm. The research used an exploratory case study comprising four participants who were purposively recruited and empowered with RtL between 2016 and 2022. The data-gathering methods used were semi-structured interviews, focus group discussions, and classroom observations to get insights into the achievements and shortcomings of the RtL pedagogy in inclusive classrooms. The qualitative data in this study was analysed using thematic analysis. The study’s findings revealed that the RtL pedagogy gave students who faced reading obstacles in inclusive classes the skills needed to read, read with meaning, and improve as readers and writers through its six-step scaffolding interactive cycle. There were challenges in employing the RtL pedagogy in inclusive classes, such as it is time-consuming and makes it difficult for teachers to adhere to the time frame stipulated by the annual teaching plan. Nevertheless, the study’s findings showed that the advantages of the RtL pedagogy outweigh the challenges. , Thesis (MEd) -- Faculty of Education, Institute for the Study of Englishes of Africa, 2024
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COVID19 and accountability in South Africa: legislation, ethics and disaster risk management
- Authors: Chapman, Emma Deidre
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419565 , vital:71655
- Description: Embargoed. Possible release in 2026 pending publication. , Thesis (MSC Pharm) -- Faculty of Pharmacy, 2023
- Full Text:
- Authors: Chapman, Emma Deidre
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419565 , vital:71655
- Description: Embargoed. Possible release in 2026 pending publication. , Thesis (MSC Pharm) -- Faculty of Pharmacy, 2023
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Development of a 3D bioprinting and standalone bioreactor unit for the production and maintenance of bioscaffolds in vitro
- Authors: Hundling, Jethro Daniel
- Date: 2021-10-29
- Subjects: Bioreactors , Tissue scaffolds , Cell culture , Polyethylene glycol Biotechnology , 3D bioprinting , Poly(ethylene glycol) diacrylate (PEGDA)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192063 , vital:45192
- Description: The most common method for in vitro cell culture currently is to grow a specific cell type in isolation, in monolayer format, adhered to a 2D culture surface. This brings about many limitations in comparison to in vivo models due to altered cell phenotypes, as caused by the culturing technique itself, and the lack of naturally occurring cell-to-cell interactions. Three dimensional mammalian cell culture technologies have the potential to overcome these limitations, and provide models more representative of natural systems. Unfortunately, the cost and difficulty associated with achieving sustainable and useful 3D mammalian cell culture is still very high, preventing its widespread adoption across scientific platforms. In this research, we investigate the feasibility of developing and producing a visible light-based 3D stereolithographic bioprinter to produce 3D scaffolds for cell culture. Furthermore, we investigate the possibility of developing and implementing a forced perfusion bioreactor system, which would support the produced scaffold and improve longer-term culture conditions. The developed 3D bioprinter, and bioreactor designs were developed and tested alongside Poly (ethylene glycol) diacrylate (PEGDA), a versatile synthetic scaffold material. PEGDA itself was also evaluated for its printability, robustness in culture conditions over time, and its ability to maintain 3D mammalian cell culture. This research showed that both the developed 3D bioprinter, and bioreactor unit were capable of producing and maintaining an easily modifiable PEGDA scaffold, in culture conditions. In addition, the PEGDA formulation developed was shown to allow for the effective and reproducible 3D cell culture conditions over the medium term, with automated media feeding. The research presented here aimed to illustrate a proof of concept that the low-cost development and production of 3D culture scaffold production and maintenance systems was feasible to the scientific research environment. This technology can then be built upon, into a system that would then allow for the broader adoption and investigation of 3D cell culture as a tool within the scientific community. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Authors: Hundling, Jethro Daniel
- Date: 2021-10-29
- Subjects: Bioreactors , Tissue scaffolds , Cell culture , Polyethylene glycol Biotechnology , 3D bioprinting , Poly(ethylene glycol) diacrylate (PEGDA)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192063 , vital:45192
- Description: The most common method for in vitro cell culture currently is to grow a specific cell type in isolation, in monolayer format, adhered to a 2D culture surface. This brings about many limitations in comparison to in vivo models due to altered cell phenotypes, as caused by the culturing technique itself, and the lack of naturally occurring cell-to-cell interactions. Three dimensional mammalian cell culture technologies have the potential to overcome these limitations, and provide models more representative of natural systems. Unfortunately, the cost and difficulty associated with achieving sustainable and useful 3D mammalian cell culture is still very high, preventing its widespread adoption across scientific platforms. In this research, we investigate the feasibility of developing and producing a visible light-based 3D stereolithographic bioprinter to produce 3D scaffolds for cell culture. Furthermore, we investigate the possibility of developing and implementing a forced perfusion bioreactor system, which would support the produced scaffold and improve longer-term culture conditions. The developed 3D bioprinter, and bioreactor designs were developed and tested alongside Poly (ethylene glycol) diacrylate (PEGDA), a versatile synthetic scaffold material. PEGDA itself was also evaluated for its printability, robustness in culture conditions over time, and its ability to maintain 3D mammalian cell culture. This research showed that both the developed 3D bioprinter, and bioreactor unit were capable of producing and maintaining an easily modifiable PEGDA scaffold, in culture conditions. In addition, the PEGDA formulation developed was shown to allow for the effective and reproducible 3D cell culture conditions over the medium term, with automated media feeding. The research presented here aimed to illustrate a proof of concept that the low-cost development and production of 3D culture scaffold production and maintenance systems was feasible to the scientific research environment. This technology can then be built upon, into a system that would then allow for the broader adoption and investigation of 3D cell culture as a tool within the scientific community. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
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In silico identification of natural inhibitory compounds against the Mycobacterium tuberculosis Enzyme Pyrazinamidase using high-throughput virtual screening techniques
- Authors: Kenyon, Thomas
- Date: 2021-10-29
- Subjects: Mycobacterium tuberculosis , Pyrazinamide , Molecular dynamics , High throughput screening (Drug development) , Mutagenesis , South African Natural Compounds database (SANCDB)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192074 , vital:45193
- Description: Tuberculosis (TB) is most commonly a pulmonary infection caused by the bacterium Mycobacterium tuberculosis. With the exception of the COVID-19 pandemic, TB was the most common cause of death due to an infectious disease for a number of years up until 2020. In 2019, 10 million people fell ill with TB worldwide and 1.4 million people died (WHO, 2020a). Additionally, multidrug-resistant TB (MDR-TB) remains a public health crisis and a health security threat. A global total of 206 030 people with multidrug- or rifampicin-resistant TB (MDR/RR-TB) were reported in 2019, a 10% increase from 186 883 in 2018. South Africa is ranked among the 48 high TB burden countries, with an estimated 360 000 people falling ill in 2019, resulting in 58 000 deaths, the majority of which being among people living with HIV. Unlike HIV, however, TB is a curable disease when managed correctly with long durations of antitubercular chemotherapy. Pyrazinamide (PZA) is an important first-line tuberculosis drug unique for its activity against latent TB. PZA is a prodrug, being converted into its active form, pyrazinoic acid (POA) by the Mtb gene pncA, coding for the pyrazinamidase enzyme (PZase). TB resistance to first-line drugs such as PZA is commonly associated with mutations in the pncA/PZase enzyme. This study aimed to identify potential novel inhibitors that bind to the active site of PZase. By making use of molecular docking studies and molecular dynamics (MD) simulations, high throughput virtual screening was performed on 623 compounds from the South African Natural Compounds database (SANCDB; https://sancdb.rubi.ru.ac.za). Ligands that selectively bound to the PZase active site were identified using docking studies, followed by MD simulations to assess ligand-PZase complex stability, Finally, hit compounds identified from the first round of MD simulations were screened again against PZase structures with high confidence point mutations known to infer PZA resistance in order to identify any novel compounds which had inhibitory potential against both WT and mutant forms of the PZase enzyme. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
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- Authors: Kenyon, Thomas
- Date: 2021-10-29
- Subjects: Mycobacterium tuberculosis , Pyrazinamide , Molecular dynamics , High throughput screening (Drug development) , Mutagenesis , South African Natural Compounds database (SANCDB)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192074 , vital:45193
- Description: Tuberculosis (TB) is most commonly a pulmonary infection caused by the bacterium Mycobacterium tuberculosis. With the exception of the COVID-19 pandemic, TB was the most common cause of death due to an infectious disease for a number of years up until 2020. In 2019, 10 million people fell ill with TB worldwide and 1.4 million people died (WHO, 2020a). Additionally, multidrug-resistant TB (MDR-TB) remains a public health crisis and a health security threat. A global total of 206 030 people with multidrug- or rifampicin-resistant TB (MDR/RR-TB) were reported in 2019, a 10% increase from 186 883 in 2018. South Africa is ranked among the 48 high TB burden countries, with an estimated 360 000 people falling ill in 2019, resulting in 58 000 deaths, the majority of which being among people living with HIV. Unlike HIV, however, TB is a curable disease when managed correctly with long durations of antitubercular chemotherapy. Pyrazinamide (PZA) is an important first-line tuberculosis drug unique for its activity against latent TB. PZA is a prodrug, being converted into its active form, pyrazinoic acid (POA) by the Mtb gene pncA, coding for the pyrazinamidase enzyme (PZase). TB resistance to first-line drugs such as PZA is commonly associated with mutations in the pncA/PZase enzyme. This study aimed to identify potential novel inhibitors that bind to the active site of PZase. By making use of molecular docking studies and molecular dynamics (MD) simulations, high throughput virtual screening was performed on 623 compounds from the South African Natural Compounds database (SANCDB; https://sancdb.rubi.ru.ac.za). Ligands that selectively bound to the PZase active site were identified using docking studies, followed by MD simulations to assess ligand-PZase complex stability, Finally, hit compounds identified from the first round of MD simulations were screened again against PZase structures with high confidence point mutations known to infer PZA resistance in order to identify any novel compounds which had inhibitory potential against both WT and mutant forms of the PZase enzyme. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
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Remote fidelity of Container-Based Network Emulators
- Authors: Peach, Schalk Willem
- Date: 2021-10-29
- Subjects: Computer networks Security measures , Intrusion detection systems (Computer security) , Computer security , Host-based intrusion detection systems (Computer security) , Emulators (Computer programs) , Computer network protocols , Container-Based Network Emulators (CBNEs) , Network Experimentation Platforms (NEPs)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192141 , vital:45199
- Description: This thesis examines if Container-Based Network Emulators (CBNEs) are able to instantiate emulated nodes that provide sufficient realism to be used in information security experiments. The realism measure used is based on the information available from the point of view of a remote attacker. During the evaluation of a Container-Based Network Emulator (CBNE) as a platform to replicate production networks for information security experiments, it was observed that nmap fingerprinting returned Operating System (OS) family and version results inconsistent with that of the host Operating System (OS). CBNEs utilise Linux namespaces, the technology used for containerisation, to instantiate \emulated" hosts for experimental networks. Linux containers partition resources of the host OS to create lightweight virtual machines that share a single OS kernel. As all emulated hosts share the same kernel in a CBNE network, there is a reasonable expectation that the fingerprints of the host OS and emulated hosts should be the same. Based on how CBNEs instantiate emulated networks and that fingerprinting returned inconsistent results, it was hypothesised that the technologies used to construct CBNEs are capable of influencing fingerprints generated by utilities such as nmap. It was predicted that hosts emulated using different CBNEs would show deviations in remotely generated fingerprints when compared to fingerprints generated for the host OS. An experimental network consisting of two emulated hosts and a Layer 2 switch was instantiated on multiple CBNEs using the same host OS. Active and passive fingerprinting was conducted between the emulated hosts to generate fingerprints and OS family and version matches. Passive fingerprinting failed to produce OS family and version matches as the fingerprint databases for these utilities are no longer maintained. For active fingerprinting the OS family results were consistent between tested systems and the host OS, though OS version results reported was inconsistent. A comparison of the generated fingerprints revealed that for certain CBNEs fingerprint features related to network stack optimisations of the host OS deviated from other CBNEs and the host OS. The hypothesis that CBNEs can influence remotely generated fingerprints was partially confirmed. One CBNE system modified Linux kernel networking options, causing a deviation from fingerprints generated for other tested systems and the host OS. The hypothesis was also partially rejected as the technologies used by CBNEs do not influence the remote fidelity of emulated hosts. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Authors: Peach, Schalk Willem
- Date: 2021-10-29
- Subjects: Computer networks Security measures , Intrusion detection systems (Computer security) , Computer security , Host-based intrusion detection systems (Computer security) , Emulators (Computer programs) , Computer network protocols , Container-Based Network Emulators (CBNEs) , Network Experimentation Platforms (NEPs)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192141 , vital:45199
- Description: This thesis examines if Container-Based Network Emulators (CBNEs) are able to instantiate emulated nodes that provide sufficient realism to be used in information security experiments. The realism measure used is based on the information available from the point of view of a remote attacker. During the evaluation of a Container-Based Network Emulator (CBNE) as a platform to replicate production networks for information security experiments, it was observed that nmap fingerprinting returned Operating System (OS) family and version results inconsistent with that of the host Operating System (OS). CBNEs utilise Linux namespaces, the technology used for containerisation, to instantiate \emulated" hosts for experimental networks. Linux containers partition resources of the host OS to create lightweight virtual machines that share a single OS kernel. As all emulated hosts share the same kernel in a CBNE network, there is a reasonable expectation that the fingerprints of the host OS and emulated hosts should be the same. Based on how CBNEs instantiate emulated networks and that fingerprinting returned inconsistent results, it was hypothesised that the technologies used to construct CBNEs are capable of influencing fingerprints generated by utilities such as nmap. It was predicted that hosts emulated using different CBNEs would show deviations in remotely generated fingerprints when compared to fingerprints generated for the host OS. An experimental network consisting of two emulated hosts and a Layer 2 switch was instantiated on multiple CBNEs using the same host OS. Active and passive fingerprinting was conducted between the emulated hosts to generate fingerprints and OS family and version matches. Passive fingerprinting failed to produce OS family and version matches as the fingerprint databases for these utilities are no longer maintained. For active fingerprinting the OS family results were consistent between tested systems and the host OS, though OS version results reported was inconsistent. A comparison of the generated fingerprints revealed that for certain CBNEs fingerprint features related to network stack optimisations of the host OS deviated from other CBNEs and the host OS. The hypothesis that CBNEs can influence remotely generated fingerprints was partially confirmed. One CBNE system modified Linux kernel networking options, causing a deviation from fingerprints generated for other tested systems and the host OS. The hypothesis was also partially rejected as the technologies used by CBNEs do not influence the remote fidelity of emulated hosts. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
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Understanding the livelihoods of Zimbabwean informal traders in South Africa: the case of Makhanda
- Musiyandaka, Tariro Henrietta
- Authors: Musiyandaka, Tariro Henrietta
- Date: 2020
- Subjects: Informal sector (Economics) South Africa Makhanda , Foreign workers, Zimbabwean South Africa Makhanda Economic conditions , Foreign workers, Zimbabwean South Africa Makhanda Social conditions , Street vendors South Africa Makhanda
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/164535 , vital:41127
- Description: Increasingly, Zimbabweans are migrating from their country for both economic and political reasons, with South Africa being the primary destination. In seeking employment in South Africa, Zimbabweans face numerous initial problems, including the high unemployment rate in the country alongside restrictions on their employment in the formal economy. In this context, Zimbabweans often turn to work in the informal economy, including as informal traders. This thesis seeks to understand the lives and livelihoods of Zimbabwean informal traders in Makhanda in the Eastern Cape Province of South Africa. Drawing upon the Sustainable Livelihoods Approach, and in the light of existing literature on Zimbabweans more broadly in South Africa, the thesis examines the livelihoods of a purposeful sampled grouping of six informal traders from Zimbabwe in Makhanda. It discusses their reasons for leaving Zimbabwe, their journey from Zimbabwe to Makhanda, relationships amongst themselves and their ongoing relationships with family back home, as well as their hopes and plans for the future. It also examines more specifically their livelihood activities, the daily challenges they face in pursuing their livelihoods and concerns about their livelihood status in South Africa. Despite the many deep-rooted systemic obstacles confronting these Zimbabwean informal traders, the thesis concludes that they demonstrate significant micro-level ingenuity in pursuing their livelihoods in South Africa. , Thesis (MA) -- Faculty of Faculty of Humanities, Sociology, 2020
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- Authors: Musiyandaka, Tariro Henrietta
- Date: 2020
- Subjects: Informal sector (Economics) South Africa Makhanda , Foreign workers, Zimbabwean South Africa Makhanda Economic conditions , Foreign workers, Zimbabwean South Africa Makhanda Social conditions , Street vendors South Africa Makhanda
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/164535 , vital:41127
- Description: Increasingly, Zimbabweans are migrating from their country for both economic and political reasons, with South Africa being the primary destination. In seeking employment in South Africa, Zimbabweans face numerous initial problems, including the high unemployment rate in the country alongside restrictions on their employment in the formal economy. In this context, Zimbabweans often turn to work in the informal economy, including as informal traders. This thesis seeks to understand the lives and livelihoods of Zimbabwean informal traders in Makhanda in the Eastern Cape Province of South Africa. Drawing upon the Sustainable Livelihoods Approach, and in the light of existing literature on Zimbabweans more broadly in South Africa, the thesis examines the livelihoods of a purposeful sampled grouping of six informal traders from Zimbabwe in Makhanda. It discusses their reasons for leaving Zimbabwe, their journey from Zimbabwe to Makhanda, relationships amongst themselves and their ongoing relationships with family back home, as well as their hopes and plans for the future. It also examines more specifically their livelihood activities, the daily challenges they face in pursuing their livelihoods and concerns about their livelihood status in South Africa. Despite the many deep-rooted systemic obstacles confronting these Zimbabwean informal traders, the thesis concludes that they demonstrate significant micro-level ingenuity in pursuing their livelihoods in South Africa. , Thesis (MA) -- Faculty of Faculty of Humanities, Sociology, 2020
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Tetra 4-(propargyloxy)phenoxy phthalocyanines: synthesis, spectroscopic, nonlinear optical and electrocatalytic properties
- Authors: Mwanza, Daniel
- Date: 2017
- Subjects: Phthalocyanines , Nonlinear optics , Electrocatalysis , Spectrum analysis , Thermogravimetry , Phthalocyanines Spectra
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/65144 , vital:28695
- Description: This study presents the synthesis, spectroscopic, photophysical and theoretical characterisation of metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (MnTPrOPhOPc) tetra 4-(4-propargyloxy) phenoxy phthalocyanines. Thermal analysis using thermogravimetric analysis (TGA) confirmed the excellent thermal stability of synthesized tetra 4-(4- propargyloxy) phenoxy phthalocyanines. The metal complexes, CoTPrOPhOPc and MnTPrOPhOPc, exhibited better thermal stability when compared to H2TPrOPhOPc. The residual percentage weight remaining was approximately 70% for CoTPrOPhOPc and MnTPrOPhOPc and 45% for H2TPrOPhOPc after 600°C, clearly confirming the stability of the metal complexes. The MTPrOPhOPcs (where M = H2, Co and Mn) complexes exhibited excellent nonlinear optical properties with strong reverse saturable absorption (RSA), especially when 560 nm excitation laser was used. Their nonlinear optical properties followed this trend: H2TPrOPhOPc > CoTPrOPhOPc > MnTPrOPhOPc. According to the trend observed, the H2TPrOPhOPc was an excellent nonlinear optical limiter when compared to the CoTPrOPhOPc and MnTPrOPhOPc. All the investigated complexes exhibited optical limiting properties comparable to the phthalocyanine complexes reported in the literature. The MTPrOPhOPc complexes were further studied for their electrocatalytic and electroanalytical properties towards the detection of hydrogen peroxide. For the electrocatalytic studies, the synthesized complexes were immobilized onto gold electrode surfaces pre-functionalized with phenylazide (Au-PAz) monolayer. Copper (I) catalyzed alkynyl-azide cycloaddition reaction was used to covalently immobilize the MTPrOPhOPcs onto the gold electrode surfaces to form Au-PAz-MTPrOPhOPc. The MTPrOPhOPcs modified gold surfaces (Au-PAz-MTPrOPhOPc) exhibited good reproducibility and stability in various electrolyte conditions. Electrochemical and surface characterisation of the functionalised gold electrode surfaces confirmed the presence of the MTPrOPhOPcs and their electroanalysis was excellent towards electrocatalytic reduction of H2O2, with the limit of detection (LoD) and limit of quantification (LoQ) in the ^M range. The electrocatalytic reduction peaks for H2O2 were observed at -0.37 V for Au-PAz-MnTPrOPhOPc and -0.31 V for Au-PAz-CoTPrOPhOPc when Ag|AgCl pseudo-reference electrode was used. The Au-PAz-MnTPrOPhOPc and Au- PAz-CoTPrOPhOPc gold electrode surfaces showed good sensitivity and reproducibility towards the electrocatalytic reduction of hydrogen peroxide in pH 7.4 phosphate buffer solution. , Thesis (MSc) -- Faculty of Science, Chemistry, 2017
- Full Text:
- Authors: Mwanza, Daniel
- Date: 2017
- Subjects: Phthalocyanines , Nonlinear optics , Electrocatalysis , Spectrum analysis , Thermogravimetry , Phthalocyanines Spectra
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/65144 , vital:28695
- Description: This study presents the synthesis, spectroscopic, photophysical and theoretical characterisation of metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (MnTPrOPhOPc) tetra 4-(4-propargyloxy) phenoxy phthalocyanines. Thermal analysis using thermogravimetric analysis (TGA) confirmed the excellent thermal stability of synthesized tetra 4-(4- propargyloxy) phenoxy phthalocyanines. The metal complexes, CoTPrOPhOPc and MnTPrOPhOPc, exhibited better thermal stability when compared to H2TPrOPhOPc. The residual percentage weight remaining was approximately 70% for CoTPrOPhOPc and MnTPrOPhOPc and 45% for H2TPrOPhOPc after 600°C, clearly confirming the stability of the metal complexes. The MTPrOPhOPcs (where M = H2, Co and Mn) complexes exhibited excellent nonlinear optical properties with strong reverse saturable absorption (RSA), especially when 560 nm excitation laser was used. Their nonlinear optical properties followed this trend: H2TPrOPhOPc > CoTPrOPhOPc > MnTPrOPhOPc. According to the trend observed, the H2TPrOPhOPc was an excellent nonlinear optical limiter when compared to the CoTPrOPhOPc and MnTPrOPhOPc. All the investigated complexes exhibited optical limiting properties comparable to the phthalocyanine complexes reported in the literature. The MTPrOPhOPc complexes were further studied for their electrocatalytic and electroanalytical properties towards the detection of hydrogen peroxide. For the electrocatalytic studies, the synthesized complexes were immobilized onto gold electrode surfaces pre-functionalized with phenylazide (Au-PAz) monolayer. Copper (I) catalyzed alkynyl-azide cycloaddition reaction was used to covalently immobilize the MTPrOPhOPcs onto the gold electrode surfaces to form Au-PAz-MTPrOPhOPc. The MTPrOPhOPcs modified gold surfaces (Au-PAz-MTPrOPhOPc) exhibited good reproducibility and stability in various electrolyte conditions. Electrochemical and surface characterisation of the functionalised gold electrode surfaces confirmed the presence of the MTPrOPhOPcs and their electroanalysis was excellent towards electrocatalytic reduction of H2O2, with the limit of detection (LoD) and limit of quantification (LoQ) in the ^M range. The electrocatalytic reduction peaks for H2O2 were observed at -0.37 V for Au-PAz-MnTPrOPhOPc and -0.31 V for Au-PAz-CoTPrOPhOPc when Ag|AgCl pseudo-reference electrode was used. The Au-PAz-MnTPrOPhOPc and Au- PAz-CoTPrOPhOPc gold electrode surfaces showed good sensitivity and reproducibility towards the electrocatalytic reduction of hydrogen peroxide in pH 7.4 phosphate buffer solution. , Thesis (MSc) -- Faculty of Science, Chemistry, 2017
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