Diversified computational approaches for the identification of orthosteric drugs, allosteric modulators and unveiling drug resistance mechanisms: application to infectious diseases
- Authors: Boateng, Rita Afriyie
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/234173 , vital:50169
- Description: Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Boateng, Rita Afriyie
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/234173 , vital:50169
- Description: Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
Dynamics of charge movement in ∞-Al2O3:C,Mg using thermoluminescence phototransferred and optically stimulated luminescence
- Authors: Lontsi Sob, Aaron Joel
- Date: 2022-04-08
- Subjects: Thermoluminescence , Optically stimulated luminescence , Phototransfer , Deep traps , Phototransferred thermoluminescence (PTTL)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294607 , vital:57237 , DOI 10.21504/10962/294607
- Description: The dosimetric features of ∞-Al2O3:C,Mg have been investigated for unannealed and annealed samples. The unannealed sample is referred to as sample A whereas the samples annealed at 700, 900 and 1200°C for 15 minutes each are referred to as samples B, C and D respectively. A glow curve of unannealed ∞-Al2O3:C,Mg measured at 1°C/s after irradiation to 2.0 Gy consists of peaks at 43, 73, 164, 195, 246, 284, 336 and 374°C respectively. For sample B (annealed at 700°C), a glow curve measured at 1°C/s after irradiation to 3.0 Gy has peaks at 46, 76, 100, 170, 199, 290, 330 and 375°C whereas the glow curve of sample C (annealed at 900°C) recorded under the same conditions consists of peaks at 49, 80, 100, 174, 206, 235, 290, 335 and 375°C respectively. Sample D (annealed at 1200°C) is the most sensitive of the four samples. A glow curve of sample D measured at 1°C/s after irradiation to 0.2 Gy has peaks at 52, 82, 102, 174, 234, 288 and 384°C respectively. The peaks are labelled I-VIII in order of appearance. The 100°C peak, labelled IIa, is induced by annealing at or above 700°C. The dose response of these peaks was studied for doses within 0.1-8.2 Gy. The reported peaks follow first-order kinetics irrespective of annealing temperature. Peaks I-III of each sample are reproduced under phototransfer for preheating up to 400°C. For the unannealed sample, the reproduced peaks are labelled A1-A3 whereas for the annealed samples, they are labelled B1-B3, C1-C3 and D1-D3 respectively. The annealing-induced peak at 100°C is reproduced as B2a, C2a and D2a for samples B, C and D respectively. A PTTL peak labelled C2b or D2b is also observed near 140°C in samples C and D. In addition to these PTTL peaks, a PTTL peak corresponding to peak IV is also found for sample D and for the unannealed sample. As the corresponding conventional peaks, the PTTL peaks of each sample follow first-order kinetics. Peak I and its corresponding PTTL peak for each sample are unstable and fade to a minimal level after 300 s of storage time. On the other hand, peak II of each sample and its corresponding PTTL peak could still be observed with delay up to 5000 s. Peak III of the unannealed sample remains stable with storage time up to 48 hours. Irrespective of annealing, the trap corresponding to peak III is the most sensitive to optical stimulation. Time-dependent profiles of PTTL from unannealed and annealed ∞-Al2O3:C,Mg were also studied. The mathematical analysis of the PTTL time-response profiles is based on experimental results. The role of various electron traps in PTTL was determined by using pulse annealing and by monitoring the dependence of peak intensity on duration of illumination for peaks not removed by preheating. The presence and role of deep traps were further demonstrated with thermally assisted optically stimulated luminescence. For the unannealed sample, the activation energy for thermal assistance is 0.033 ± 0.001 eV and the activation energy for thermal i quenching is 1.043 ± 0.001 eV. For sample C, the activation energy for thermal assistance is 0.044 ± 0.003 eV whereas that for thermal quenching is 1.110 ± 0.006 eV. The values for the activation energy for thermal assistance are lower than those reported in literature. Only the values for the activation energy for thermal quenching are somewhat comparable to values reported elsewhere. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Lontsi Sob, Aaron Joel
- Date: 2022-04-08
- Subjects: Thermoluminescence , Optically stimulated luminescence , Phototransfer , Deep traps , Phototransferred thermoluminescence (PTTL)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294607 , vital:57237 , DOI 10.21504/10962/294607
- Description: The dosimetric features of ∞-Al2O3:C,Mg have been investigated for unannealed and annealed samples. The unannealed sample is referred to as sample A whereas the samples annealed at 700, 900 and 1200°C for 15 minutes each are referred to as samples B, C and D respectively. A glow curve of unannealed ∞-Al2O3:C,Mg measured at 1°C/s after irradiation to 2.0 Gy consists of peaks at 43, 73, 164, 195, 246, 284, 336 and 374°C respectively. For sample B (annealed at 700°C), a glow curve measured at 1°C/s after irradiation to 3.0 Gy has peaks at 46, 76, 100, 170, 199, 290, 330 and 375°C whereas the glow curve of sample C (annealed at 900°C) recorded under the same conditions consists of peaks at 49, 80, 100, 174, 206, 235, 290, 335 and 375°C respectively. Sample D (annealed at 1200°C) is the most sensitive of the four samples. A glow curve of sample D measured at 1°C/s after irradiation to 0.2 Gy has peaks at 52, 82, 102, 174, 234, 288 and 384°C respectively. The peaks are labelled I-VIII in order of appearance. The 100°C peak, labelled IIa, is induced by annealing at or above 700°C. The dose response of these peaks was studied for doses within 0.1-8.2 Gy. The reported peaks follow first-order kinetics irrespective of annealing temperature. Peaks I-III of each sample are reproduced under phototransfer for preheating up to 400°C. For the unannealed sample, the reproduced peaks are labelled A1-A3 whereas for the annealed samples, they are labelled B1-B3, C1-C3 and D1-D3 respectively. The annealing-induced peak at 100°C is reproduced as B2a, C2a and D2a for samples B, C and D respectively. A PTTL peak labelled C2b or D2b is also observed near 140°C in samples C and D. In addition to these PTTL peaks, a PTTL peak corresponding to peak IV is also found for sample D and for the unannealed sample. As the corresponding conventional peaks, the PTTL peaks of each sample follow first-order kinetics. Peak I and its corresponding PTTL peak for each sample are unstable and fade to a minimal level after 300 s of storage time. On the other hand, peak II of each sample and its corresponding PTTL peak could still be observed with delay up to 5000 s. Peak III of the unannealed sample remains stable with storage time up to 48 hours. Irrespective of annealing, the trap corresponding to peak III is the most sensitive to optical stimulation. Time-dependent profiles of PTTL from unannealed and annealed ∞-Al2O3:C,Mg were also studied. The mathematical analysis of the PTTL time-response profiles is based on experimental results. The role of various electron traps in PTTL was determined by using pulse annealing and by monitoring the dependence of peak intensity on duration of illumination for peaks not removed by preheating. The presence and role of deep traps were further demonstrated with thermally assisted optically stimulated luminescence. For the unannealed sample, the activation energy for thermal assistance is 0.033 ± 0.001 eV and the activation energy for thermal i quenching is 1.043 ± 0.001 eV. For sample C, the activation energy for thermal assistance is 0.044 ± 0.003 eV whereas that for thermal quenching is 1.110 ± 0.006 eV. The values for the activation energy for thermal assistance are lower than those reported in literature. Only the values for the activation energy for thermal quenching are somewhat comparable to values reported elsewhere. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
Effect of adding a probiotic to an aquaponic system on plant and fish growth, water quality, and microbial diversity
- Authors: Kasozi, Nasser
- Date: 2022-04-08
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/294596 , vital:57236
- Description: Thesis embargoed. Release date April 2023. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Kasozi, Nasser
- Date: 2022-04-08
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/294596 , vital:57236
- Description: Thesis embargoed. Release date April 2023. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
English additional language student teachers’ development of oral strategic competence and confidence
- Authors: Meyers, Rozanne Elanore
- Date: 2022-04-08
- Subjects: Student teaching South Africa , Communicative competence South Africa , Oral communication , Native language and education , Language arts , Verbal ability , Multilingual education
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263613 , vital:53643
- Description: This case study sought to understand how oral strategic and discourse competence and confidence developed in student teachers using English, their additional language, firstly as a tool of learning and secondly, as a medium of instruction in education environments. Within the broad qualitative approach an interpretive framework was adopted using multiple data collection tools. This was in order to privilege detailed accounts of participants’ experiences. Namely, unstructured interviews, drawings, observational checklists, and selfassessment questionnaires. Participants’ oral strategic and discourse competence were assessed using an observation checklist as they presented micro-teaching lessons. Additionally, participants completed a self-assessment questionnaire, reflecting on their oral competence after conducting their micro-teaching lessons. These perceptions were confirmed through a discussion of drawings that illustrated how they perceived themselves during lectures when they had to use English during oral interaction with lecturers and fellow students. Finally, unstructured interviews were conducted after participants completed their micro-teaching lessons and after participants had completed their drawings. The raw data from the four tools were analysed using a thematic approach. Main themes and categories were analysed and discussed to provide answers to the research questions. Data correlated the attitude of participants towards English and their level of oral confidence and competence. The main findings were that students were motivated to develop their oral English competence because they believed it was an important skill for teachers to possess. This motivation also proved to be a leading factor in participants’ competence despite the negative emotions they identified during spoken exchanges. Furthermore, the analysis found that collaborating with fellow students in making meaning of oral communication during lectures, increased students’ oral competence and their confidence because they were communicating in smaller groups. However, in certain situations, collaborating with students also decreased their confidence. Findings indicated that reciprocal facial expressions and the body language of those who engaged orally with the student teachers, increased their oral confidence as it served as an indication to them that they were understood. Based on these findings, recommendations are made regarding interactions during lectures for teacher training programmes in Higher Education in South Africa, for lecturers and lecturing practices, and curriculum designers in the South African Department of Education. , Thesis (MEd) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Meyers, Rozanne Elanore
- Date: 2022-04-08
- Subjects: Student teaching South Africa , Communicative competence South Africa , Oral communication , Native language and education , Language arts , Verbal ability , Multilingual education
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263613 , vital:53643
- Description: This case study sought to understand how oral strategic and discourse competence and confidence developed in student teachers using English, their additional language, firstly as a tool of learning and secondly, as a medium of instruction in education environments. Within the broad qualitative approach an interpretive framework was adopted using multiple data collection tools. This was in order to privilege detailed accounts of participants’ experiences. Namely, unstructured interviews, drawings, observational checklists, and selfassessment questionnaires. Participants’ oral strategic and discourse competence were assessed using an observation checklist as they presented micro-teaching lessons. Additionally, participants completed a self-assessment questionnaire, reflecting on their oral competence after conducting their micro-teaching lessons. These perceptions were confirmed through a discussion of drawings that illustrated how they perceived themselves during lectures when they had to use English during oral interaction with lecturers and fellow students. Finally, unstructured interviews were conducted after participants completed their micro-teaching lessons and after participants had completed their drawings. The raw data from the four tools were analysed using a thematic approach. Main themes and categories were analysed and discussed to provide answers to the research questions. Data correlated the attitude of participants towards English and their level of oral confidence and competence. The main findings were that students were motivated to develop their oral English competence because they believed it was an important skill for teachers to possess. This motivation also proved to be a leading factor in participants’ competence despite the negative emotions they identified during spoken exchanges. Furthermore, the analysis found that collaborating with fellow students in making meaning of oral communication during lectures, increased students’ oral competence and their confidence because they were communicating in smaller groups. However, in certain situations, collaborating with students also decreased their confidence. Findings indicated that reciprocal facial expressions and the body language of those who engaged orally with the student teachers, increased their oral confidence as it served as an indication to them that they were understood. Based on these findings, recommendations are made regarding interactions during lectures for teacher training programmes in Higher Education in South Africa, for lecturers and lecturing practices, and curriculum designers in the South African Department of Education. , Thesis (MEd) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
Environmental governance, agency and multi-actor dynamics in Southern Africa
- Authors: Falayi, Menelisi
- Date: 2022-04-08
- Subjects: Environmental law South Africa , Environmental law Zimbabwe , Natural resources Management , Conservation of natural resources South Africa Eastern Cape , Natural resources Co-management South Africa Eastern Cape , Range policy South Africa Eastern Cape , Range management South Africa Eastern Cape , Forest reserves Law and legislation Zimbabwe , Agent (Philosophy)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232355 , vital:49984 , DOI 10.21504/10962/232355
- Description: Natural resources have, since the beginning of time, played a central role in supporting human wellbeing. In southern Africa resource consumption has drastically increased over the past 50 years, resulting in biodiversity loss and land degradation. To reduce land degradation and biodiversity loss rates in the region, great emphasis has been placed on building effective governance structures that can deliver environmentally and socially sustainable outcomes. However, environmental governance continues to be a major challenge in the management and conservation of natural resources in the region. Thus, there is renewed scientific and policy interest in strengthening the capacity of governance systems. This thesis is timely; there is an increasing desire by policymakers and land users in the region to develop governance options that enhance multi-actor participation and collaboration. Therefore, this thesis explores the dynamics that influence the capacity of natural resource governance systems in southern Africa, predominately in Machubeni, South Africa (chapters 3 and 4) and in State forests in Zimbabwe (chapter 5). To achieve this aim, four stand-alone manuscripts that answer the following questions are included: 1. How have governance challenges manifested in natural resource management between 2010 and 2020 in southern Africa? 2. How were the governance objectives and attributes applied per historical period and what were the influencing drivers? a. What key drivers influenced rangeland condition over time in Machubeni? 3. How have multi-actor ties changed since the external investment in landscape governance and management in Machubeni, South Africa? 4. What role has agency played in the effectiveness of co-management initiatives in southern Africa? To answer the questions, I applied Bennett and Satterfield’s practical framework for understanding the objectives, attributes and elements of governance and Archer’s ii morphogenetic framework. The study employed a mixed-methods approach which included a scoping review methodology (chapter 2), household surveys, historical records, life history interviews, focus group discussions (chapters 3 and 4), social network analysis (chapter 4) and secondary data analysis (chapter 5). Results from the scoping review (chapter 2) show that research on governance challenges has not increased since 2010. Results suggest that governance challenges related to the maintenance of system integrity and functioning, specifically lack of coordination, accountability, skills, and resources to define effective natural resource management, were the most reported in the literature. Chapter 3 elucidates the importance of history in evaluating the application of governance objectives and rangeland condition in resource-poor areas. The results show that the residual impacts of the ‘ghost of environmental history’ still influence governance dynamics in Machubeni, South Africa. Furthermore, contemporary challenges are linked to history. Chapter 4 shows that transformative spaces enhance collaboration and knowledge sharing between land users, government, and researchers. Finally, chapter 5 employs the morphogenetic framework to assess how agency (the capacity of people and organisations to make choices and decisions about their lives) influenced the effectiveness of co-management initiatives in southern Africa. The results suggest that in attempts to shift governance towards greater effectiveness, more attention should be paid to building individual and group agency. Based on the results from the empirical chapters, the study identified three key focus areas that require more attention in order to build effective landscape governance and management in southern Africa:(i) acknowledging the role of historical legacies and context,(ii) building and developing agency, capacity and trust amongst actors and (iii) the development of sustainable landscape financing mechanisms that will enable governance systems to deliver socially and environmentally sustainable outcomes. , Ubutyebi bendalo buqhubekile budlala indima ebalulekileyo ekuxhaseni impilo-ntle yoluntu. Ngenxa yokubaluleka kobutyebi bendalo kubomi babantu, ukusetyenziswa kobutyebi kuye kwanda kakhulu kule minyaka eyi-50 idlulileyo, okubangela ulahleko lweentlobo-ntlobo yezityalo nezilwanyana eziphilayo kunye nokhukhuliseko komhlaba kumazantsi e-Afrika. Ukunciphisa ukhukhuliseko komhlaba kunye namazinga alahleko eentlobo-ntlobo zezityalo nezilwanyana eziphilayo kummandla, ugxininiso olukhulu luye lwabekwa ekwakhiweni kweziseko zolawulo ezisebenzayo ezinokuzisa iziphumo ezizinzileyo ngokwemeko yendalo nentlalo. Nangona kunjalo, ulawulo lwendalo lusaqhubeka lungumceli mngeni omkhulu kulawulo nolondolozo lobutyebi bendalo kulo mmandla. Ngoko ke, kukho umdla ohlaziyiweyo wenzululwazi nomgaqo-nkqubo ekomelezeni isakhono seenkqubo zolawulo. Le ithisisi ifike ngexesha kuba kukho umnqweno okhulayo kummandla ngabaqulunqi bomgaqo-nkqubo kunye nabasebenzisi bomhlaba ukuphuhlisa iinketho zolawulo eziphakamisa ukuthatha inxaxheba kwabantu abaninzi kunye nentsebenziswano. Ke ngoko, le ithisisi iphonononga izinto eziphembelela isakhono seenkqubo zolawulo lobutyebi bendalo kumazantsi eAfrika, ikakhulu eMachubeni, eMzantsi Afrika (isahluko 3 no 4) nakumahlathi kaRhulumente eZimbabwe (isahluko 5). Ukuphumeza le njongo, kufakwe layo: 1. Ibonakaliswe njani imiceli mngeni yolawulo kulawulo lwendalo phakathi ko-2010 no 2020 kumazantsi eAfrika? 2. Zeziphi injongo zolawulo kunye neempawu ezisetyenzisiweyo ngokwexesha lembali? a. Zeziphi ezona zinto eziqhuba phambili eziphembelele ukusetyenziswa kweenjongo zolawulo kunye neempawu ngokuhamba kwexesha? b. Zeziphi iindlela ezibalulekileyo ezichaphazele ngayo iimeko zamadlelo ekuhambeni kwexesha? 3. Atshintshe njani amakhonkco obudlelwane phakathi kwabathathi-nxaxheba ukusukela oko kutyalo-mali lwangaphandle kulawulo lobume bomhlaba eMachubeni, eMzantsi Afrika? 4. Yiyiphi indima edlalwe sisakhono sokwenza ukhetho kunye nezigqibo malunga nobomi bakho ekusebenzeni ngempumelelo kwamalinge olawulo ngokubambisana kumazantsi e-Afrika? Ukuphendula imibuzo, ndisebenzise isakhelo esisebenzayo sikaBennett kunye noSatterfield ukuqonda iinjongo kunye neempawu zolawulo kunye nesakhelo se-Archer's morphogenetic. Uphononongo lusebenzise iindlela ezixubeneyo ezibandakanya indlela yokuphonononga iincwadi zophando (isahluko 2), uphando lwamakhaya, iirekhodi zembali, udliwano-ndlebe lwembali yobomi, iingxoxo zeqela eligxininisiweyo (isahluko 3 kunye no 4), uhlalutyo lonxibelelwano nobudlelwane boluntu (isahluko 4) kunye nohlalutyo lwedatha ethathwe ngomnye umntu. (isahluko 5). Iziphumo ezivela kuphononongo lweencwadi zophando (isahluko 2) zibonakalisa ukuba uphando ngemiceli mngeni yolawulo alunyukanga ukusukela ngo-2010. Iziphumo zibonisa ukuba imiceli mngeni yolawulo enxulumene nokugcinwa kwemfezeko nokusebenza kwenkqubo, ngokukodwa ukungabikho kolungelelwaniso, uxanduva, izakhono, kunye nezibonelelo zokuchaza ulawulo lwemithombo yendalo olusebenzayo, yayiyeyona ichazwe kwiincwadi. Isahluko sesi-3 sicacisa ukubaluleka kwembali ekuvavanyeni ukusetyenziswa kweenjongo zolawulo kunye nemeko yemihlaba ekwiindawo ezihlwempuzekileyo ngezibonelelo. Iziphumo zibonisa ukuba uchaphazeleko oshiyekileyo we-‘ghost of environmental history’ zisenefuthe kulawulo lwenguquko eMachubeni, eMzantsi Afrika. Ngaphezu koko, imiceli mngeni yangoku inxulunyaniswa nembali. Isahluko sesi-4 sibonisa ukuba iindawo eziguqulayo ziphucula intsebenziswano nokwabelana ngolwazi phakathi kwabasebenzisi bomhlaba, urhulumente nabaphandi. Ekugqibeleni, isahluko sesi-5 sisebenzisa isakhelo se-morphogenetic ukuvavanya indlela isakhono sabantu kunye nemibutho sokwenza ukhetho kunye nezigqibo malunga nobomi babo ibe nefuthe ekusebenzeni kwamanyathelo olawulo ngokubambisana kumazantsi e-Afrika. Iziphumo zibonisa ukuba kwiinzame zokutshintsha ulawulo ukuze lusebenze kangangoko, ingqwalasela engaphezulu kufuneka ibekwe ekwakheni isakhono, somntu neseqela, sokwenza ukhetho kunye nezigqibo malunga nobomi babo. Ngokusekelwe kwiziphumo ezivela kwizahluko zobungqina, uphononongo luchonge imiba emithathu engundoqo ekugxilwe kuzo ezifuna ingqwalaselo ethe kratya ukuze kwakhiwe ulawulo lwemihlaba olusebenzayo kumazantsi e-Afrika. Ngokukodwa: (i) ukuqaphela indima yelifa lembali kunye nomxholo (ii) ukwakha nokuphuhlisa isakhono v sokwenza ukhetho kunye nezigqibo malunga nobomi, isakhono kunye nokuthembana phakathi kwabathathi-nxaxheba kunye (iii) nokuphuhliswa kweendlela ezizinzileyo zenkxaso-mali yendawo eziya kwenza ukuba iinkqubo zolawulo zinike iziphumo ezizinzileyo ngokwentlalo nendalo. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Falayi, Menelisi
- Date: 2022-04-08
- Subjects: Environmental law South Africa , Environmental law Zimbabwe , Natural resources Management , Conservation of natural resources South Africa Eastern Cape , Natural resources Co-management South Africa Eastern Cape , Range policy South Africa Eastern Cape , Range management South Africa Eastern Cape , Forest reserves Law and legislation Zimbabwe , Agent (Philosophy)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232355 , vital:49984 , DOI 10.21504/10962/232355
- Description: Natural resources have, since the beginning of time, played a central role in supporting human wellbeing. In southern Africa resource consumption has drastically increased over the past 50 years, resulting in biodiversity loss and land degradation. To reduce land degradation and biodiversity loss rates in the region, great emphasis has been placed on building effective governance structures that can deliver environmentally and socially sustainable outcomes. However, environmental governance continues to be a major challenge in the management and conservation of natural resources in the region. Thus, there is renewed scientific and policy interest in strengthening the capacity of governance systems. This thesis is timely; there is an increasing desire by policymakers and land users in the region to develop governance options that enhance multi-actor participation and collaboration. Therefore, this thesis explores the dynamics that influence the capacity of natural resource governance systems in southern Africa, predominately in Machubeni, South Africa (chapters 3 and 4) and in State forests in Zimbabwe (chapter 5). To achieve this aim, four stand-alone manuscripts that answer the following questions are included: 1. How have governance challenges manifested in natural resource management between 2010 and 2020 in southern Africa? 2. How were the governance objectives and attributes applied per historical period and what were the influencing drivers? a. What key drivers influenced rangeland condition over time in Machubeni? 3. How have multi-actor ties changed since the external investment in landscape governance and management in Machubeni, South Africa? 4. What role has agency played in the effectiveness of co-management initiatives in southern Africa? To answer the questions, I applied Bennett and Satterfield’s practical framework for understanding the objectives, attributes and elements of governance and Archer’s ii morphogenetic framework. The study employed a mixed-methods approach which included a scoping review methodology (chapter 2), household surveys, historical records, life history interviews, focus group discussions (chapters 3 and 4), social network analysis (chapter 4) and secondary data analysis (chapter 5). Results from the scoping review (chapter 2) show that research on governance challenges has not increased since 2010. Results suggest that governance challenges related to the maintenance of system integrity and functioning, specifically lack of coordination, accountability, skills, and resources to define effective natural resource management, were the most reported in the literature. Chapter 3 elucidates the importance of history in evaluating the application of governance objectives and rangeland condition in resource-poor areas. The results show that the residual impacts of the ‘ghost of environmental history’ still influence governance dynamics in Machubeni, South Africa. Furthermore, contemporary challenges are linked to history. Chapter 4 shows that transformative spaces enhance collaboration and knowledge sharing between land users, government, and researchers. Finally, chapter 5 employs the morphogenetic framework to assess how agency (the capacity of people and organisations to make choices and decisions about their lives) influenced the effectiveness of co-management initiatives in southern Africa. The results suggest that in attempts to shift governance towards greater effectiveness, more attention should be paid to building individual and group agency. Based on the results from the empirical chapters, the study identified three key focus areas that require more attention in order to build effective landscape governance and management in southern Africa:(i) acknowledging the role of historical legacies and context,(ii) building and developing agency, capacity and trust amongst actors and (iii) the development of sustainable landscape financing mechanisms that will enable governance systems to deliver socially and environmentally sustainable outcomes. , Ubutyebi bendalo buqhubekile budlala indima ebalulekileyo ekuxhaseni impilo-ntle yoluntu. Ngenxa yokubaluleka kobutyebi bendalo kubomi babantu, ukusetyenziswa kobutyebi kuye kwanda kakhulu kule minyaka eyi-50 idlulileyo, okubangela ulahleko lweentlobo-ntlobo yezityalo nezilwanyana eziphilayo kunye nokhukhuliseko komhlaba kumazantsi e-Afrika. Ukunciphisa ukhukhuliseko komhlaba kunye namazinga alahleko eentlobo-ntlobo zezityalo nezilwanyana eziphilayo kummandla, ugxininiso olukhulu luye lwabekwa ekwakhiweni kweziseko zolawulo ezisebenzayo ezinokuzisa iziphumo ezizinzileyo ngokwemeko yendalo nentlalo. Nangona kunjalo, ulawulo lwendalo lusaqhubeka lungumceli mngeni omkhulu kulawulo nolondolozo lobutyebi bendalo kulo mmandla. Ngoko ke, kukho umdla ohlaziyiweyo wenzululwazi nomgaqo-nkqubo ekomelezeni isakhono seenkqubo zolawulo. Le ithisisi ifike ngexesha kuba kukho umnqweno okhulayo kummandla ngabaqulunqi bomgaqo-nkqubo kunye nabasebenzisi bomhlaba ukuphuhlisa iinketho zolawulo eziphakamisa ukuthatha inxaxheba kwabantu abaninzi kunye nentsebenziswano. Ke ngoko, le ithisisi iphonononga izinto eziphembelela isakhono seenkqubo zolawulo lobutyebi bendalo kumazantsi eAfrika, ikakhulu eMachubeni, eMzantsi Afrika (isahluko 3 no 4) nakumahlathi kaRhulumente eZimbabwe (isahluko 5). Ukuphumeza le njongo, kufakwe layo: 1. Ibonakaliswe njani imiceli mngeni yolawulo kulawulo lwendalo phakathi ko-2010 no 2020 kumazantsi eAfrika? 2. Zeziphi injongo zolawulo kunye neempawu ezisetyenzisiweyo ngokwexesha lembali? a. Zeziphi ezona zinto eziqhuba phambili eziphembelele ukusetyenziswa kweenjongo zolawulo kunye neempawu ngokuhamba kwexesha? b. Zeziphi iindlela ezibalulekileyo ezichaphazele ngayo iimeko zamadlelo ekuhambeni kwexesha? 3. Atshintshe njani amakhonkco obudlelwane phakathi kwabathathi-nxaxheba ukusukela oko kutyalo-mali lwangaphandle kulawulo lobume bomhlaba eMachubeni, eMzantsi Afrika? 4. Yiyiphi indima edlalwe sisakhono sokwenza ukhetho kunye nezigqibo malunga nobomi bakho ekusebenzeni ngempumelelo kwamalinge olawulo ngokubambisana kumazantsi e-Afrika? Ukuphendula imibuzo, ndisebenzise isakhelo esisebenzayo sikaBennett kunye noSatterfield ukuqonda iinjongo kunye neempawu zolawulo kunye nesakhelo se-Archer's morphogenetic. Uphononongo lusebenzise iindlela ezixubeneyo ezibandakanya indlela yokuphonononga iincwadi zophando (isahluko 2), uphando lwamakhaya, iirekhodi zembali, udliwano-ndlebe lwembali yobomi, iingxoxo zeqela eligxininisiweyo (isahluko 3 kunye no 4), uhlalutyo lonxibelelwano nobudlelwane boluntu (isahluko 4) kunye nohlalutyo lwedatha ethathwe ngomnye umntu. (isahluko 5). Iziphumo ezivela kuphononongo lweencwadi zophando (isahluko 2) zibonakalisa ukuba uphando ngemiceli mngeni yolawulo alunyukanga ukusukela ngo-2010. Iziphumo zibonisa ukuba imiceli mngeni yolawulo enxulumene nokugcinwa kwemfezeko nokusebenza kwenkqubo, ngokukodwa ukungabikho kolungelelwaniso, uxanduva, izakhono, kunye nezibonelelo zokuchaza ulawulo lwemithombo yendalo olusebenzayo, yayiyeyona ichazwe kwiincwadi. Isahluko sesi-3 sicacisa ukubaluleka kwembali ekuvavanyeni ukusetyenziswa kweenjongo zolawulo kunye nemeko yemihlaba ekwiindawo ezihlwempuzekileyo ngezibonelelo. Iziphumo zibonisa ukuba uchaphazeleko oshiyekileyo we-‘ghost of environmental history’ zisenefuthe kulawulo lwenguquko eMachubeni, eMzantsi Afrika. Ngaphezu koko, imiceli mngeni yangoku inxulunyaniswa nembali. Isahluko sesi-4 sibonisa ukuba iindawo eziguqulayo ziphucula intsebenziswano nokwabelana ngolwazi phakathi kwabasebenzisi bomhlaba, urhulumente nabaphandi. Ekugqibeleni, isahluko sesi-5 sisebenzisa isakhelo se-morphogenetic ukuvavanya indlela isakhono sabantu kunye nemibutho sokwenza ukhetho kunye nezigqibo malunga nobomi babo ibe nefuthe ekusebenzeni kwamanyathelo olawulo ngokubambisana kumazantsi e-Afrika. Iziphumo zibonisa ukuba kwiinzame zokutshintsha ulawulo ukuze lusebenze kangangoko, ingqwalasela engaphezulu kufuneka ibekwe ekwakheni isakhono, somntu neseqela, sokwenza ukhetho kunye nezigqibo malunga nobomi babo. Ngokusekelwe kwiziphumo ezivela kwizahluko zobungqina, uphononongo luchonge imiba emithathu engundoqo ekugxilwe kuzo ezifuna ingqwalaselo ethe kratya ukuze kwakhiwe ulawulo lwemihlaba olusebenzayo kumazantsi e-Afrika. Ngokukodwa: (i) ukuqaphela indima yelifa lembali kunye nomxholo (ii) ukwakha nokuphuhlisa isakhono v sokwenza ukhetho kunye nezigqibo malunga nobomi, isakhono kunye nokuthembana phakathi kwabathathi-nxaxheba kunye (iii) nokuphuhliswa kweendlela ezizinzileyo zenkxaso-mali yendawo eziya kwenza ukuba iinkqubo zolawulo zinike iziphumo ezizinzileyo ngokwentlalo nendalo. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
Ethnobotany and conservation biology of Warburgia salutaris (G.Bertol.) Chiov., a threatened medicinal plant in southern Mozambique
- Authors: Senkoro, Annae Maria
- Date: 2022-04-08
- Subjects: Ethnobotany Mozambique , Conservation biology Mozambique , Canellaceae Habitat Mozambique , Canellaceae Genetics , Warburgia salutaris Habitat Mozambique , Warburgia salutaris Genetics , Endangered plants Mozambique , Biogeography Climatic factors Mozambique , Traditional medicine Mozambique , Traditional ecological knowledge Mozambique
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232967 , vital:50042 , DOI 10.21504/10962/232967
- Description: Warburgia salutaris, locally known as “chibaha” (Ronga, Tsonga), “isiBhaha” (Zulu) and “siBhaha” (Siswati), is one of the most highly-valued medicinal plant species in southern Africa. Its bark has long been employed to treat bacterial and fungal infections, and it is often a front line herbal treatment for malaria. The species is popular in rural and urban areas due to its lower price compared to commercial pharmaceuticals and because of its long-standing spiritual and symbolic significance. Consequently, W. salutaris is threatened in Malawi, South Africa and Swaziland and is believed to be extincted in the wild in Zimbabwe. In Mozambique, where the tree is confined to the southern part of the country, it is considered vulnerable due to high local demand and cross-border export. Although there is limited research, further work is urgently needed to provide the basis for options and strategies to achieve desired outcomes. This study aimed to explore different approaches for the conservation of W. salutaris in the Lebombo Mountains (LM), the Tembe River (TR) and the Futi Corridor (FC) areas, in southern Mozambique. For this, potential distribution, socio cultural factors that influenced sustainable management of the species, demography, harvest impact, genetic diversity and population differentiation were considered. The kuenm package in R, 2 846 occurrence and 11 environmental data were used to model the potential current and future distribution in 2050 and 2070 using four general circulation models (CESM1(BGC), ACCESS1.3, FIO-ESM and IPSL-CM5A-MR) under representative concentration pathways (RCPs) 4.5 and 8.5. The extent of occurrence (EOO) and habitat suitability (HS) were also determined. Stratified random semi-structured interviews with 182 heads of households were carried out to explore cultural and socio incentives of use, compared knowledge distribution, determine local management practices and explore local ecological knowledge related to the species in the three study areas. In addition, 17 focus group discussion were conducted to clarify issues raised during household interviews. One hundred and twenty four quadrants were used to determine the abundance and population structure. The Simpson index of dominance, permutation index and quotient between consecutive classes were used to assess population stability, and an eight point scale was used to evaluate the extent of bark damages. Genomic deoxyribonucleic acid (gDNA) (n=48) was used to assessed genetic diversity and population structure through the newly developed single sequence repeats (SSR) molecular markers. Model selected was statistical significant for prediction of potential distribution of W. salutaris in southern Mozambique (partial ROC =0.00, omission rate = 0.04 and delta AICc = 0.00). The current environmental conditions mostly explained by climatic predictor, indicated in general, the potential distribution on areas of occurrence observed during the field work in southern Mozambique. Future project suggested an increase of climatic suitable areas in all the general circulation models in both conservative and pessimistic climatic scenarios (RCPs 4.5 and 8.5, respectively) in 2050 and 2070, and consequently the increase of HS and the EOO. Results of this work suggests W. salutaris would not extinct at least in the coming 50 years due to climate change but other threats such as overexploitation of the species need to be addressed. With increase of climatic suitable areas, conservation and management of this species could focus on reintroduction and cultivation for recovery of the species, with the help of time. W. salutaris was used for medicinal purposes to treat 12 health problems, with the bark being the most commonly used part (92% of informants). Knowledge of the species uses differed significantly between the three study areas but not with respondent gender or age. Informants also mentioned a considerable number of alternative species of W. salutaris (37 species in LM, 33 species in TR and 17 species in FC). Local ecological knowledge on the ecological niche of the species also varied substantial in the three areas with both types of knowledge generally higher in the Tembe River area. Local management practises were revealed mostly on harvesting through vertical bark stripping cited by 100% of informants in TR, 61.6% FC and 51.7 LM (71% of all informants). Yet most (64.3% of all informants, corresponding to 98.4% in TR, 51.7% in Fc and 41.7% LM) used non-traditional harvesting tools (machete) bark removal. For sustainable use of the species, consideration should be given to combined conservation strategies such as the use of alternative species with the same application, substitution of bark by leaves, and increases in alternative sources of plant material through cultivation. The densities of alive stems were not statistically different in the three areas but was higher in LM (mean of 4500.3±9209.8 stems/ha). Equally the mean densities of recruits (diameter ≤2 cm) were not considerable different but was higher in the FC (3296.8±9116.7 stems/ha). The regression analyses for the three study area revealed negative slopes, indicating more recruits and fewer individuals in larger classes. The Simpson indexes of dominance, permutation indexes and quotients between the consecutive size classes suggested some levels of population instability in the three areas. Harvesting took place in the eight point scale, all size classes were harvested but preference was higher on intermediate (15.1-20 cm) or larger (>20 cm) size classes in all the study areas but gatherers avoided harvesting bark from recruits. Although the mean densities of harvested stem was not significant this work indicated higher levels of stem destruction in FC. Harvested dead stems ware significant in the three areas and FC had the higher of (39.5±85.9 stems/ha) compared to 7.6±19.1 and 2.1±4.3 in TR and LM, respectively. Equally, the density of physiologically stressed stems differed substantially in the three areas with higher in FC 20.5± 75.5 stems/ha compared to 18.7±82.9 stems/ha in TR and 3.8±11.8 stems/ha in LM. This results suggests implementation of protection measures such as the inclusion of the species in the national CITES list to regulated cross-border trade and strengthening of the law enforcement. Genetic diversity, structure and gene flow in the exiting populations of southern Mozambique revealed that despite fragmentation and overexploitation, this species maintains a relatively high level of genetic diversity supporting the existence of random mating. Two genetic groups were found corresponding to the northern (LM and TR) and southern (FC) areas. The study suggests that, if local extinctions occurred in Mozambique, the pepper-bark tree persisted in sufficient numbers to retain a large proportion of genetic diversity. Management plans should concentrate on maintaining this high level of genetic variability through both in and ex-situ conservation actions. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Senkoro, Annae Maria
- Date: 2022-04-08
- Subjects: Ethnobotany Mozambique , Conservation biology Mozambique , Canellaceae Habitat Mozambique , Canellaceae Genetics , Warburgia salutaris Habitat Mozambique , Warburgia salutaris Genetics , Endangered plants Mozambique , Biogeography Climatic factors Mozambique , Traditional medicine Mozambique , Traditional ecological knowledge Mozambique
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232967 , vital:50042 , DOI 10.21504/10962/232967
- Description: Warburgia salutaris, locally known as “chibaha” (Ronga, Tsonga), “isiBhaha” (Zulu) and “siBhaha” (Siswati), is one of the most highly-valued medicinal plant species in southern Africa. Its bark has long been employed to treat bacterial and fungal infections, and it is often a front line herbal treatment for malaria. The species is popular in rural and urban areas due to its lower price compared to commercial pharmaceuticals and because of its long-standing spiritual and symbolic significance. Consequently, W. salutaris is threatened in Malawi, South Africa and Swaziland and is believed to be extincted in the wild in Zimbabwe. In Mozambique, where the tree is confined to the southern part of the country, it is considered vulnerable due to high local demand and cross-border export. Although there is limited research, further work is urgently needed to provide the basis for options and strategies to achieve desired outcomes. This study aimed to explore different approaches for the conservation of W. salutaris in the Lebombo Mountains (LM), the Tembe River (TR) and the Futi Corridor (FC) areas, in southern Mozambique. For this, potential distribution, socio cultural factors that influenced sustainable management of the species, demography, harvest impact, genetic diversity and population differentiation were considered. The kuenm package in R, 2 846 occurrence and 11 environmental data were used to model the potential current and future distribution in 2050 and 2070 using four general circulation models (CESM1(BGC), ACCESS1.3, FIO-ESM and IPSL-CM5A-MR) under representative concentration pathways (RCPs) 4.5 and 8.5. The extent of occurrence (EOO) and habitat suitability (HS) were also determined. Stratified random semi-structured interviews with 182 heads of households were carried out to explore cultural and socio incentives of use, compared knowledge distribution, determine local management practices and explore local ecological knowledge related to the species in the three study areas. In addition, 17 focus group discussion were conducted to clarify issues raised during household interviews. One hundred and twenty four quadrants were used to determine the abundance and population structure. The Simpson index of dominance, permutation index and quotient between consecutive classes were used to assess population stability, and an eight point scale was used to evaluate the extent of bark damages. Genomic deoxyribonucleic acid (gDNA) (n=48) was used to assessed genetic diversity and population structure through the newly developed single sequence repeats (SSR) molecular markers. Model selected was statistical significant for prediction of potential distribution of W. salutaris in southern Mozambique (partial ROC =0.00, omission rate = 0.04 and delta AICc = 0.00). The current environmental conditions mostly explained by climatic predictor, indicated in general, the potential distribution on areas of occurrence observed during the field work in southern Mozambique. Future project suggested an increase of climatic suitable areas in all the general circulation models in both conservative and pessimistic climatic scenarios (RCPs 4.5 and 8.5, respectively) in 2050 and 2070, and consequently the increase of HS and the EOO. Results of this work suggests W. salutaris would not extinct at least in the coming 50 years due to climate change but other threats such as overexploitation of the species need to be addressed. With increase of climatic suitable areas, conservation and management of this species could focus on reintroduction and cultivation for recovery of the species, with the help of time. W. salutaris was used for medicinal purposes to treat 12 health problems, with the bark being the most commonly used part (92% of informants). Knowledge of the species uses differed significantly between the three study areas but not with respondent gender or age. Informants also mentioned a considerable number of alternative species of W. salutaris (37 species in LM, 33 species in TR and 17 species in FC). Local ecological knowledge on the ecological niche of the species also varied substantial in the three areas with both types of knowledge generally higher in the Tembe River area. Local management practises were revealed mostly on harvesting through vertical bark stripping cited by 100% of informants in TR, 61.6% FC and 51.7 LM (71% of all informants). Yet most (64.3% of all informants, corresponding to 98.4% in TR, 51.7% in Fc and 41.7% LM) used non-traditional harvesting tools (machete) bark removal. For sustainable use of the species, consideration should be given to combined conservation strategies such as the use of alternative species with the same application, substitution of bark by leaves, and increases in alternative sources of plant material through cultivation. The densities of alive stems were not statistically different in the three areas but was higher in LM (mean of 4500.3±9209.8 stems/ha). Equally the mean densities of recruits (diameter ≤2 cm) were not considerable different but was higher in the FC (3296.8±9116.7 stems/ha). The regression analyses for the three study area revealed negative slopes, indicating more recruits and fewer individuals in larger classes. The Simpson indexes of dominance, permutation indexes and quotients between the consecutive size classes suggested some levels of population instability in the three areas. Harvesting took place in the eight point scale, all size classes were harvested but preference was higher on intermediate (15.1-20 cm) or larger (>20 cm) size classes in all the study areas but gatherers avoided harvesting bark from recruits. Although the mean densities of harvested stem was not significant this work indicated higher levels of stem destruction in FC. Harvested dead stems ware significant in the three areas and FC had the higher of (39.5±85.9 stems/ha) compared to 7.6±19.1 and 2.1±4.3 in TR and LM, respectively. Equally, the density of physiologically stressed stems differed substantially in the three areas with higher in FC 20.5± 75.5 stems/ha compared to 18.7±82.9 stems/ha in TR and 3.8±11.8 stems/ha in LM. This results suggests implementation of protection measures such as the inclusion of the species in the national CITES list to regulated cross-border trade and strengthening of the law enforcement. Genetic diversity, structure and gene flow in the exiting populations of southern Mozambique revealed that despite fragmentation and overexploitation, this species maintains a relatively high level of genetic diversity supporting the existence of random mating. Two genetic groups were found corresponding to the northern (LM and TR) and southern (FC) areas. The study suggests that, if local extinctions occurred in Mozambique, the pepper-bark tree persisted in sufficient numbers to retain a large proportion of genetic diversity. Management plans should concentrate on maintaining this high level of genetic variability through both in and ex-situ conservation actions. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
Exploring learners’ engagement with literacy in a book club
- Authors: Jamieson, Vuyokazi
- Date: 2022-04-08
- Subjects: Book clubs (Discussion groups) South Africa Makhanda , Literacy South Africa Makhanda , High school students Books and reading South Africa Makhanda , Books and reading South Africa Makhanda , Reading, Psychology of , Service learning South Africa Makhanda , Critical realism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263601 , vital:53642
- Description: This study observes the literacy engagement of a group of learners enrolled in Grades 8–10 in Nombulelo High School, a poorly-resourced school in the city of Makhanda in the Eastern Cape, South Africa. The learners participated in a book club hosted and run by St Andrew’s College, a privileged independent school, as a community engagement initiative. The idea of extending literacy engagement and engagement with written texts beyond textbooks used in schools is critical for learners with ambitions to enter higher education. Studying at a university requires a lot of reading, and if reading has not been taken up as a practice that involves more than ‘text consulting’ (Geisler, 1994) students will be unlikely to read the number of texts required of them. Studies (see Geisler, 1994 for an overview) have shown how the literacy of the university is very different to school based literacies. The assumption behind the study on which this thesis reports is that engagement with fictional texts might promote reading and bring about understandings of this activity as enjoyable and not a task only associated with schooling. The study is underpinned by a critical realist philosophy which allowed for the identification of structures and mechanisms that led to the emergence of literacy events in learners’ lives and to their experiences and observations of those events. The study was guided by the following questions: How do learners from a poorly-resourced high school engage around fictional texts in the context of a book club? What enables or constrains this engagement? The study was impacted by the Covid-19 pandemic in that lockdown requirements meant that learners from St Andrew’s College could not participate in the book club as much as anticipated initially as they had been forced to return home to pursue online learning. Learners from Nombuelo High School were, however, granted access to College premises, where they met in the school library following strict Covid protocols. The study draws on in-depth interviews, observations and document analysis of five learners from Nombulelo High School who participated in the book club, as well as on book reviews they wrote for the book club website. The critical realist analysis allows for the identification of mechanisms in learners’ homes and communities that enable literacies, including those that are screen-based such as using a computer, mobile phones and other technologies. This study found evidence of challenges regarding school based texts, reading fictional texts and viewing it as an enrichment of the school project. Because of children were African the emergence of communal practices and story telling is woven throughout the results section. However, is an example of the complexity of social and economic challenges facing South African marginalised schools. , Thesis (MEd) -- Faculty of Education, Centre for Higher Education Research, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Jamieson, Vuyokazi
- Date: 2022-04-08
- Subjects: Book clubs (Discussion groups) South Africa Makhanda , Literacy South Africa Makhanda , High school students Books and reading South Africa Makhanda , Books and reading South Africa Makhanda , Reading, Psychology of , Service learning South Africa Makhanda , Critical realism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263601 , vital:53642
- Description: This study observes the literacy engagement of a group of learners enrolled in Grades 8–10 in Nombulelo High School, a poorly-resourced school in the city of Makhanda in the Eastern Cape, South Africa. The learners participated in a book club hosted and run by St Andrew’s College, a privileged independent school, as a community engagement initiative. The idea of extending literacy engagement and engagement with written texts beyond textbooks used in schools is critical for learners with ambitions to enter higher education. Studying at a university requires a lot of reading, and if reading has not been taken up as a practice that involves more than ‘text consulting’ (Geisler, 1994) students will be unlikely to read the number of texts required of them. Studies (see Geisler, 1994 for an overview) have shown how the literacy of the university is very different to school based literacies. The assumption behind the study on which this thesis reports is that engagement with fictional texts might promote reading and bring about understandings of this activity as enjoyable and not a task only associated with schooling. The study is underpinned by a critical realist philosophy which allowed for the identification of structures and mechanisms that led to the emergence of literacy events in learners’ lives and to their experiences and observations of those events. The study was guided by the following questions: How do learners from a poorly-resourced high school engage around fictional texts in the context of a book club? What enables or constrains this engagement? The study was impacted by the Covid-19 pandemic in that lockdown requirements meant that learners from St Andrew’s College could not participate in the book club as much as anticipated initially as they had been forced to return home to pursue online learning. Learners from Nombuelo High School were, however, granted access to College premises, where they met in the school library following strict Covid protocols. The study draws on in-depth interviews, observations and document analysis of five learners from Nombulelo High School who participated in the book club, as well as on book reviews they wrote for the book club website. The critical realist analysis allows for the identification of mechanisms in learners’ homes and communities that enable literacies, including those that are screen-based such as using a computer, mobile phones and other technologies. This study found evidence of challenges regarding school based texts, reading fictional texts and viewing it as an enrichment of the school project. Because of children were African the emergence of communal practices and story telling is woven throughout the results section. However, is an example of the complexity of social and economic challenges facing South African marginalised schools. , Thesis (MEd) -- Faculty of Education, Centre for Higher Education Research, 2022
- Full Text:
- Date Issued: 2022-04-08
Inhibition of aluminium corrosion using phthalocyanines: Experimental and computational studies
- Authors: Nnaji, Nnaemeka Joshua
- Date: 2022-04-08
- Subjects: Aluminum Corrosion , Electrochemistry , Phthalocyanines , Corrosion and anti-corrosives , Protective coatings , Density functionals
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294643 , vital:57240 , DOI 10.21504/10962/294643
- Description: Metal deterioration over time is a process known as corrosion, an electrochemical process, which can occur by surface chemical actions on metals by its environment. Metal corrosion have great economic, security, and environmental consequences, and its control is a major research area in corrosion science. Amongst the different corrosion protecting approaches, the use of corrosion inhibitors and protective coatings have attracted enormous research interest in this area of scholasticism. This has necessitated the computational and electrochemical investigations of aluminium corrosion inhibitive potentials of some compounds in 1M HCl. Metal free (5_H2), ClGa(III) (5_Ga) and Co(II) (5_Co) tetrakis(4-acetamidophenoxy)phthalocyanines as well as Co(II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (6) and Co(II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (7) were synthesized for the first time and studied for corrosion inhibition. The reported ClGa(III) tetrakis(benzo[d]thiazol-2-yl-thio)phthalocyaninine (1), ClGa(III) tetrakis(benzo[d]thiazol-2ylphenoxy)phthalocyanine (2), ClGa(III) tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyanine) (3) and ClGa(III) tetrakis-4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)-bis(phthalocyanine) (4) were also employed for corrosion inhibition of Al in HCl. Corrosion inhibition measurements using electrochemical techniques showed that increased π conjugation caused (1) to (2) to outperform (1a) and (2a) respectively as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. For similar reason, (4) outperformed 2. (1) and (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. Measurements obtained from electrochemical impedance spectroscopy gave corrosion inhibition efficiency values of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution and showed that electrodeposited phthalocyanines have enhanced aluminium corrosion retardation than when in solution. The use of reduced graphene oxide nanosheets (rGONS) alone as aluminium corrosion inhibitor is discouraged because of poor aluminium corrosion inhibition in 1M HCl. However, synergistic effects were observed when rGONS was mixed each with (4) and (3). (5_H2), (5_Ga) and (5_Co) decreased aluminium corrosion in 1M HCl and observation was that the heavier the atom the more decreased the protection and the free base performed best of the three. Studied tertbutylphenoxy-derived CoPcs (6 and 7) exhibited good aluminium corrosion inhibition properties in studied acidic solution and the unsymmetric CoPc (6) which has more heteroatoms, gave better performance. Quantum chemical calculations involved the use of density functional theoretical (DFT) approaches and gave results which corroborated with experimental findings. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Nnaji, Nnaemeka Joshua
- Date: 2022-04-08
- Subjects: Aluminum Corrosion , Electrochemistry , Phthalocyanines , Corrosion and anti-corrosives , Protective coatings , Density functionals
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294643 , vital:57240 , DOI 10.21504/10962/294643
- Description: Metal deterioration over time is a process known as corrosion, an electrochemical process, which can occur by surface chemical actions on metals by its environment. Metal corrosion have great economic, security, and environmental consequences, and its control is a major research area in corrosion science. Amongst the different corrosion protecting approaches, the use of corrosion inhibitors and protective coatings have attracted enormous research interest in this area of scholasticism. This has necessitated the computational and electrochemical investigations of aluminium corrosion inhibitive potentials of some compounds in 1M HCl. Metal free (5_H2), ClGa(III) (5_Ga) and Co(II) (5_Co) tetrakis(4-acetamidophenoxy)phthalocyanines as well as Co(II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (6) and Co(II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (7) were synthesized for the first time and studied for corrosion inhibition. The reported ClGa(III) tetrakis(benzo[d]thiazol-2-yl-thio)phthalocyaninine (1), ClGa(III) tetrakis(benzo[d]thiazol-2ylphenoxy)phthalocyanine (2), ClGa(III) tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyanine) (3) and ClGa(III) tetrakis-4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)-bis(phthalocyanine) (4) were also employed for corrosion inhibition of Al in HCl. Corrosion inhibition measurements using electrochemical techniques showed that increased π conjugation caused (1) to (2) to outperform (1a) and (2a) respectively as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. For similar reason, (4) outperformed 2. (1) and (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. Measurements obtained from electrochemical impedance spectroscopy gave corrosion inhibition efficiency values of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution and showed that electrodeposited phthalocyanines have enhanced aluminium corrosion retardation than when in solution. The use of reduced graphene oxide nanosheets (rGONS) alone as aluminium corrosion inhibitor is discouraged because of poor aluminium corrosion inhibition in 1M HCl. However, synergistic effects were observed when rGONS was mixed each with (4) and (3). (5_H2), (5_Ga) and (5_Co) decreased aluminium corrosion in 1M HCl and observation was that the heavier the atom the more decreased the protection and the free base performed best of the three. Studied tertbutylphenoxy-derived CoPcs (6 and 7) exhibited good aluminium corrosion inhibition properties in studied acidic solution and the unsymmetric CoPc (6) which has more heteroatoms, gave better performance. Quantum chemical calculations involved the use of density functional theoretical (DFT) approaches and gave results which corroborated with experimental findings. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
Neutral winds and tides over South Africa
- Authors: Ojo, Taiwo Theophilus
- Date: 2022-04-08
- Subjects: Atmospheric tides , Ionosondes , Fabry-Perot interferometers , Thermospheric winds , Servomechanisms , Climatology , Neutral winds , Horizontal Wind Model (HWM)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232459 , vital:49993 , DOI 10.21504/10962/232459
- Description: This thesis presents the first results of a climatology of nighttime thermospheric neutral winds between February 2018 and January 2019 measured by a Fabry-Perot interferometer (FPI) in Sutherland, South Africa (32.2°S, 20.48°E; geomagnetic latitude: 40.7°S). This FPI measures the nighttime oxygen airglow emission at 630.0 nm, which has a peak intensity at an altitude of roughly 250 km. The performance of the Horizontal Wind Model (HWM14) was evaluated by comparing results from HWM14 with the FPI measurements. The results showed that the model had a better agreement with the measurements for meridional component compared to the zonal component. In addition, the HWM14 zonal wind consistently peaked several hours (~3 h) prior to the measured wind, creating what looks like a phase shift compared to the measured wind. An investigation of this apparent phase shift revealed it to be a consequence of a difference in phase shift of the terdiunal tide. Since ionosondes are more prolific with wider temporal and spatial coverage than FPIs, nighttime meridional winds aligned to the magnetic meridian were inferred from the peak height (hmF2) of ionospheric data taken from South Africa ionosonde network using the servo model during February 2018-June 2019. These were compared with FPI measured meridional wind and benchmarked with HWM14 and Magnetic mEridional NeuTrAl Thermospheric (MENTAT) model. The amplitudes and trends of the calculated meridional winds across all four ionosonde stations agreed relatively well with the observed data, especially during the summer months. Furthermore, the results confirmed that the ionosonde station located closest to the FPI, i.e. Hermanus station, had better agreement with measurements compared to the stations located at further distances. The extraction and analysis of atmospheric tides, namely the diurnal, semidiurnal, terdiurnal and 6-hour components from the FPI as well as the long-term tidal winds variations from the thermospheric wind measurements were investigated. The results showed that the semidiurnal peak mostly had the highest peak across all the months, indicating that the semidiurnal tides dominate the dynamic structure of the upper mesosphere at midlatitudes, consistent with previous observation over midlatitudes. Futhermore, the signature of the diurnal tide in the meridional (zonal) wind was stronger in winter (summer) and weaker in summer (winter). Also, semidiurnal tide didn't show any trend with season, while the terdiurnal tide was dominant in summer (zonal) and winter (meridional). Lastly, the 6 hour tide was detected intermittently during the period of the study and had the weakest signature (i.e. lowest amplitudes). , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Ojo, Taiwo Theophilus
- Date: 2022-04-08
- Subjects: Atmospheric tides , Ionosondes , Fabry-Perot interferometers , Thermospheric winds , Servomechanisms , Climatology , Neutral winds , Horizontal Wind Model (HWM)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232459 , vital:49993 , DOI 10.21504/10962/232459
- Description: This thesis presents the first results of a climatology of nighttime thermospheric neutral winds between February 2018 and January 2019 measured by a Fabry-Perot interferometer (FPI) in Sutherland, South Africa (32.2°S, 20.48°E; geomagnetic latitude: 40.7°S). This FPI measures the nighttime oxygen airglow emission at 630.0 nm, which has a peak intensity at an altitude of roughly 250 km. The performance of the Horizontal Wind Model (HWM14) was evaluated by comparing results from HWM14 with the FPI measurements. The results showed that the model had a better agreement with the measurements for meridional component compared to the zonal component. In addition, the HWM14 zonal wind consistently peaked several hours (~3 h) prior to the measured wind, creating what looks like a phase shift compared to the measured wind. An investigation of this apparent phase shift revealed it to be a consequence of a difference in phase shift of the terdiunal tide. Since ionosondes are more prolific with wider temporal and spatial coverage than FPIs, nighttime meridional winds aligned to the magnetic meridian were inferred from the peak height (hmF2) of ionospheric data taken from South Africa ionosonde network using the servo model during February 2018-June 2019. These were compared with FPI measured meridional wind and benchmarked with HWM14 and Magnetic mEridional NeuTrAl Thermospheric (MENTAT) model. The amplitudes and trends of the calculated meridional winds across all four ionosonde stations agreed relatively well with the observed data, especially during the summer months. Furthermore, the results confirmed that the ionosonde station located closest to the FPI, i.e. Hermanus station, had better agreement with measurements compared to the stations located at further distances. The extraction and analysis of atmospheric tides, namely the diurnal, semidiurnal, terdiurnal and 6-hour components from the FPI as well as the long-term tidal winds variations from the thermospheric wind measurements were investigated. The results showed that the semidiurnal peak mostly had the highest peak across all the months, indicating that the semidiurnal tides dominate the dynamic structure of the upper mesosphere at midlatitudes, consistent with previous observation over midlatitudes. Futhermore, the signature of the diurnal tide in the meridional (zonal) wind was stronger in winter (summer) and weaker in summer (winter). Also, semidiurnal tide didn't show any trend with season, while the terdiurnal tide was dominant in summer (zonal) and winter (meridional). Lastly, the 6 hour tide was detected intermittently during the period of the study and had the weakest signature (i.e. lowest amplitudes). , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
Quantifying the impacts of cactus biological control agents in South Africa
- Authors: Mnqeta, Zezethu
- Date: 2022-04-08
- Subjects: Cactus Biological control South Africa , Noxious weeds South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Cochineal insect South Africa , Mealybugs South Africa , Agricultural productivity South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294631 , vital:57239 , DOI 10.21504/10962/294631
- Description: Invasive alien cacti are prominent weeds that threaten indigenous biodiversity and have a negative impact on agricultural productivity in South Africa. These plants are problematic because they form dense thickets that reduce the carrying capacity of rangelands; restrict the movement of livestock and wildlife thus reducing access to shade and water sources; and are directly harmful to livestock, wildlife and people due to their sharp spines. Biological control is the most effective, affordable and environmentally friendly method to control invasive alien cacti and minimize their negative impacts. Cochineal insects (Dactylopius spp.: Dactylopiidae) and the gall-forming mealybug, Hypogeococcus sp. (Pseudococcidae) are used as biological control agents for cacti. The agents are however poor dispersers, so mass-rearing and augmentative releases are required in order to establish the agents at sites where they are needed. This study aimed to evaluate the mass-rearing and release efforts of cactus biological control in South Africa, quantify the impact of the biological control agents on cactus plant populations through long-term monitoring, and assess the benefits accrued due to the biological control agents through the perceptions of land-users. An assessment of the effectiveness of the release effort for cactus biological control agents was conducted by comparing where biological control agents have been released with the known distribution of the target weeds. Only 26% of the quarter degree squares that are known to be occupied by invasive alien cacti have had biological control agents released in them. This indicated that the mass-rearing and release efforts in South Africa are inadequate and should be increased, especially in areas where few releases have been made and many cacti are present, such as the Limpopo Province. The impact of the biological control agents on cactus plant populations was assessed by monitoring agent densities, target plant densities and target plant reproductive outputs before and after releases. Plant biomass and reproductive output were reduced by biological control agents for three of the target weeds that were assessed, while the duration of the study was too short to measure reductions for the fourth target weed. Benefits to land-users were then quantified through a questionnaire survey. Land-users perceived biological control as an effective management option, with 81% of the land-users reporting that there was less invasive alien cactus after releasing biological control agents on their land. Forty-nine percent of the land-users believed that the negative impacts of the cactus had been reduced and that they benefited more from their land since control was achieved. Since land-users were only interviewed within four years of the releases being conducted, it is expected that the percentage of land-users who gained benefits from biological control will increase in future. Ninety-seven percent of the land-users stated that the agents were safe and had not fed on any other plants or had any detrimental impacts. These perceptions indicated that land-users regarded biological control as a safe and effective method of controlling invasive alien cacti. This study confirms that biological control is an effective and safe way of controlling invasive alien Cactaceae. It is also the first to assess some of the benefits that land-users have accrued due to biological control of cactus weeds. It is however evident that a greater mass-rearing and release effort is required for South Africa to get the maximum benefits possible from the use of the biological control agents for cactus weeds that are available in the country. , Izityalo ze-cactus ezisuka kwamanye amazwe zilukhula olubalaseleyo, olwenza ingxaki kwintlobo ngeentlobo zezityalo nezilwanyana kwaye ezizityalo zinefuthe neziphumo ezingalunganga kwimveliso yezolimo eMzantsi Afrika. Ezi zizityalo ziyingxaki kuba zenza amatyholo ashinyeneyo athi anciphise umthamo wokusebenzisa umhlaba: zinqanda ukuhamba nogkukhululekileyo kwemfuyo nezilwanyana zasendle ngokwenza oko zingakwazi ukufikelela emthuzini xa kutshisa nakwimithombo yamanzi yokusela; zikwayiyo nengozi kwimfuyo, izilwanyana zasendle kunye nabantu ngenxa yamave abukhali afumaneka kwezizityalo. Ukulawula nokwehliza ubunzini nezinga lemigcipheko yezizityalo, kusetyenziswa indlela ekuthiwa yi-biological control. Lendlela yeyona ndlela isebenza ngokuphucukileyo, efikelelayo, nengenabungozi kokusingqongileyo. Izinambuzane ze- cochineal (i-Dactylopius spp.: Dactylopiidae) kunye ne-mealybug, i-Hypogeococcus sp. (Pseudococcidae) zisetyenziswe njengezixhobo ze-biological control ezinceda ukulawula ezizityalo ze-cactus zingafunekiyo. Ingxaki yazo ezizinambuzane zizixhobo ze-biological control zingentla kukuba azikwazi kuzisasaza ngokwazo ukuba zifikelele nakwizityalo ezikude ngoko ke ukukhuliswa nokukhutshwa ngobuninzi bazo kuyafuneka ukukhawulelana nalengxaki kunye nokwandisa amathuba wokuba zifikelele kuzozonke izityalo ze-cactus ekufuneka zizilawule. Olu phononongo lujolise ekuvavanyeni iinzame zokukhulisa ngobuninzi nokukhupha ezezinambuzane zizixhobo ze-bioloigical control zokulawula izityalo ze-cactus eMzantsi Afrika, ukujonga ubungakanani befuthe notshintsho elenziwa zezinambuzane zizixhobo ze-bioloigical control kwizityalo ze-cactus emva kwexesha elide lokuzijonga, kunye nokuvavanya inzuzo efunyenwe ngenxa yokulawula ezizityalo ze-cactus ngokwemibono yabasebenzisi bomhlaba. Uvavanyo lweenzame zokukhutshwa kwezixhobo zezixhobo zezinambuzane ze-bioloigical control kwizityalo ze-cactus lwenziwa ngokuthelekisa iindawo apho izixhobo zezinambuzane ze-biological control zikhutshwe khona kunye neendawo apho izityalo ze-cactus kwaziwayo ukuba ziyafumaneka khona. Yi-26% kuphela yesikwere sekota eyaziwayo ukuba kukhona izityalo ze-cactus nalapho kukhutshwe khona kwezinambuzane ezizixhobo ze-biological control. Oku kubonisa ukuba iinzame zokukhulisa nokukhutshwa kwezinambuzane ezizixhobo ze-biological control eMzantsi Afrika azanelanga kwaye kufuneka zandiswe, ngakumbi kwiindawo apho kukho ukhutsho olumbalwa olwenziweyo kunye nezityalo ze-cactus ezininzi ezifumaneka khona, njengePhondo laseLimpopo. Iimpembelelo yokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwizityalo ze-cactus zavavanywa ngokujonga ubunizi bezinambuzane ezizixhobo ze-biological control, ukuxinana kwezityalo ze-cactus ekujoliswe kuzo kunye nemveliso yokuzala kwezityalo ze-cactus phambi nasemva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control. Ubungakanani bezityalo ze-cactus kunye nemveliso yokuzala ziye zacutheka emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwinzityalo ezintathu ze-cactus ebekujoliswe uvavanyo kuzo, ngelixa ixesha lophononongo lalifutshane kakhulu ukuvavanya unciphiso kwisityalo se-cactus sesine. Izibonelelo zabasebenzisi bomhlaba zaye zavavanywa kusetyenziswa uhlobo lwemibuzo. Abasebenzisi bomhlaba balubona ukusetyenziswa kwezinambuzane ezizixhobo ze-biological control njengendlela yolawulo olusebenzayo, yi81% yabasebenzisi bomhlaba echaze ukuba izityalo ze-cactus zecuthekile emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control emhlabeni wabo. Amashumi amane anesithoba eepesenti zabasebenzisi bomhlaba bakholelwa ukuba impembelelo ezingalunganga ze-cactus zincitshisiwe kwaye baxhamle kakhulu kumhlaba wabo okoko lwaphunyenzwa. Oludliwano-ndlebe belwenziwe kubasebenzisi bomhlaba kwisithuba seminyaka emine emva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control, kulindeleke ukuba ipesenti yabasebenzisi bomhlaba abathe bafumana izibonelelo kwi-biological control lonyuke kwixesha elizayo. Amashumi alithoba anesixhenxe ekhulwini abasebenzisi bomhlaba bachaze ukuba izinambuzane ezizixhobo ze-biological control zikhuselekile kwaye khange zidle kuzo naziphi na ezinye izityalo ezingezi eze-cactus ebekujoliswe kuzo okanye zineempembelelo eyingozi. Ezi mbono ziyabonisa ukuba abasebenzi bomhlaba bayithatha i-biological control njengendlela ekhuselekileyo nesebenzayo yokulawula izityalo ze-cactus zamanye amazwe. Olu phononongo luqinisekisa ukuba ulawulo olusebenzisa izinambuzane ezizixhobo ze-biological control yindlela esebenzayo nekhuselekileyo yokulawula iCactaceae yamanye amazwe. Ikwangolokuqala ukuvavanya ezinye zezibonelelo ezizuzwe ngabasebenzisi bomhlaba ngenxa ye-biological control yezityalo ze-cactus. Nangona kunjalo kucacile ukuba ukwandisa inzame zokukhulisa nokukhupha ngobuninzi izinambuzane ezizixhobo ze-biological control kuyafuneka ukuze uMzantsi Afrika ufumane izibonelelo eziphakamileyo enokubakho ngokusetyenziswa kwe zinambuzane ezizixhobo ze-biological control zokulawula ukhula lwe-cactus olukhoyo kweli lizwe. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Mnqeta, Zezethu
- Date: 2022-04-08
- Subjects: Cactus Biological control South Africa , Noxious weeds South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Cochineal insect South Africa , Mealybugs South Africa , Agricultural productivity South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294631 , vital:57239 , DOI 10.21504/10962/294631
- Description: Invasive alien cacti are prominent weeds that threaten indigenous biodiversity and have a negative impact on agricultural productivity in South Africa. These plants are problematic because they form dense thickets that reduce the carrying capacity of rangelands; restrict the movement of livestock and wildlife thus reducing access to shade and water sources; and are directly harmful to livestock, wildlife and people due to their sharp spines. Biological control is the most effective, affordable and environmentally friendly method to control invasive alien cacti and minimize their negative impacts. Cochineal insects (Dactylopius spp.: Dactylopiidae) and the gall-forming mealybug, Hypogeococcus sp. (Pseudococcidae) are used as biological control agents for cacti. The agents are however poor dispersers, so mass-rearing and augmentative releases are required in order to establish the agents at sites where they are needed. This study aimed to evaluate the mass-rearing and release efforts of cactus biological control in South Africa, quantify the impact of the biological control agents on cactus plant populations through long-term monitoring, and assess the benefits accrued due to the biological control agents through the perceptions of land-users. An assessment of the effectiveness of the release effort for cactus biological control agents was conducted by comparing where biological control agents have been released with the known distribution of the target weeds. Only 26% of the quarter degree squares that are known to be occupied by invasive alien cacti have had biological control agents released in them. This indicated that the mass-rearing and release efforts in South Africa are inadequate and should be increased, especially in areas where few releases have been made and many cacti are present, such as the Limpopo Province. The impact of the biological control agents on cactus plant populations was assessed by monitoring agent densities, target plant densities and target plant reproductive outputs before and after releases. Plant biomass and reproductive output were reduced by biological control agents for three of the target weeds that were assessed, while the duration of the study was too short to measure reductions for the fourth target weed. Benefits to land-users were then quantified through a questionnaire survey. Land-users perceived biological control as an effective management option, with 81% of the land-users reporting that there was less invasive alien cactus after releasing biological control agents on their land. Forty-nine percent of the land-users believed that the negative impacts of the cactus had been reduced and that they benefited more from their land since control was achieved. Since land-users were only interviewed within four years of the releases being conducted, it is expected that the percentage of land-users who gained benefits from biological control will increase in future. Ninety-seven percent of the land-users stated that the agents were safe and had not fed on any other plants or had any detrimental impacts. These perceptions indicated that land-users regarded biological control as a safe and effective method of controlling invasive alien cacti. This study confirms that biological control is an effective and safe way of controlling invasive alien Cactaceae. It is also the first to assess some of the benefits that land-users have accrued due to biological control of cactus weeds. It is however evident that a greater mass-rearing and release effort is required for South Africa to get the maximum benefits possible from the use of the biological control agents for cactus weeds that are available in the country. , Izityalo ze-cactus ezisuka kwamanye amazwe zilukhula olubalaseleyo, olwenza ingxaki kwintlobo ngeentlobo zezityalo nezilwanyana kwaye ezizityalo zinefuthe neziphumo ezingalunganga kwimveliso yezolimo eMzantsi Afrika. Ezi zizityalo ziyingxaki kuba zenza amatyholo ashinyeneyo athi anciphise umthamo wokusebenzisa umhlaba: zinqanda ukuhamba nogkukhululekileyo kwemfuyo nezilwanyana zasendle ngokwenza oko zingakwazi ukufikelela emthuzini xa kutshisa nakwimithombo yamanzi yokusela; zikwayiyo nengozi kwimfuyo, izilwanyana zasendle kunye nabantu ngenxa yamave abukhali afumaneka kwezizityalo. Ukulawula nokwehliza ubunzini nezinga lemigcipheko yezizityalo, kusetyenziswa indlela ekuthiwa yi-biological control. Lendlela yeyona ndlela isebenza ngokuphucukileyo, efikelelayo, nengenabungozi kokusingqongileyo. Izinambuzane ze- cochineal (i-Dactylopius spp.: Dactylopiidae) kunye ne-mealybug, i-Hypogeococcus sp. (Pseudococcidae) zisetyenziswe njengezixhobo ze-biological control ezinceda ukulawula ezizityalo ze-cactus zingafunekiyo. Ingxaki yazo ezizinambuzane zizixhobo ze-biological control zingentla kukuba azikwazi kuzisasaza ngokwazo ukuba zifikelele nakwizityalo ezikude ngoko ke ukukhuliswa nokukhutshwa ngobuninzi bazo kuyafuneka ukukhawulelana nalengxaki kunye nokwandisa amathuba wokuba zifikelele kuzozonke izityalo ze-cactus ekufuneka zizilawule. Olu phononongo lujolise ekuvavanyeni iinzame zokukhulisa ngobuninzi nokukhupha ezezinambuzane zizixhobo ze-bioloigical control zokulawula izityalo ze-cactus eMzantsi Afrika, ukujonga ubungakanani befuthe notshintsho elenziwa zezinambuzane zizixhobo ze-bioloigical control kwizityalo ze-cactus emva kwexesha elide lokuzijonga, kunye nokuvavanya inzuzo efunyenwe ngenxa yokulawula ezizityalo ze-cactus ngokwemibono yabasebenzisi bomhlaba. Uvavanyo lweenzame zokukhutshwa kwezixhobo zezixhobo zezinambuzane ze-bioloigical control kwizityalo ze-cactus lwenziwa ngokuthelekisa iindawo apho izixhobo zezinambuzane ze-biological control zikhutshwe khona kunye neendawo apho izityalo ze-cactus kwaziwayo ukuba ziyafumaneka khona. Yi-26% kuphela yesikwere sekota eyaziwayo ukuba kukhona izityalo ze-cactus nalapho kukhutshwe khona kwezinambuzane ezizixhobo ze-biological control. Oku kubonisa ukuba iinzame zokukhulisa nokukhutshwa kwezinambuzane ezizixhobo ze-biological control eMzantsi Afrika azanelanga kwaye kufuneka zandiswe, ngakumbi kwiindawo apho kukho ukhutsho olumbalwa olwenziweyo kunye nezityalo ze-cactus ezininzi ezifumaneka khona, njengePhondo laseLimpopo. Iimpembelelo yokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwizityalo ze-cactus zavavanywa ngokujonga ubunizi bezinambuzane ezizixhobo ze-biological control, ukuxinana kwezityalo ze-cactus ekujoliswe kuzo kunye nemveliso yokuzala kwezityalo ze-cactus phambi nasemva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control. Ubungakanani bezityalo ze-cactus kunye nemveliso yokuzala ziye zacutheka emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwinzityalo ezintathu ze-cactus ebekujoliswe uvavanyo kuzo, ngelixa ixesha lophononongo lalifutshane kakhulu ukuvavanya unciphiso kwisityalo se-cactus sesine. Izibonelelo zabasebenzisi bomhlaba zaye zavavanywa kusetyenziswa uhlobo lwemibuzo. Abasebenzisi bomhlaba balubona ukusetyenziswa kwezinambuzane ezizixhobo ze-biological control njengendlela yolawulo olusebenzayo, yi81% yabasebenzisi bomhlaba echaze ukuba izityalo ze-cactus zecuthekile emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control emhlabeni wabo. Amashumi amane anesithoba eepesenti zabasebenzisi bomhlaba bakholelwa ukuba impembelelo ezingalunganga ze-cactus zincitshisiwe kwaye baxhamle kakhulu kumhlaba wabo okoko lwaphunyenzwa. Oludliwano-ndlebe belwenziwe kubasebenzisi bomhlaba kwisithuba seminyaka emine emva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control, kulindeleke ukuba ipesenti yabasebenzisi bomhlaba abathe bafumana izibonelelo kwi-biological control lonyuke kwixesha elizayo. Amashumi alithoba anesixhenxe ekhulwini abasebenzisi bomhlaba bachaze ukuba izinambuzane ezizixhobo ze-biological control zikhuselekile kwaye khange zidle kuzo naziphi na ezinye izityalo ezingezi eze-cactus ebekujoliswe kuzo okanye zineempembelelo eyingozi. Ezi mbono ziyabonisa ukuba abasebenzi bomhlaba bayithatha i-biological control njengendlela ekhuselekileyo nesebenzayo yokulawula izityalo ze-cactus zamanye amazwe. Olu phononongo luqinisekisa ukuba ulawulo olusebenzisa izinambuzane ezizixhobo ze-biological control yindlela esebenzayo nekhuselekileyo yokulawula iCactaceae yamanye amazwe. Ikwangolokuqala ukuvavanya ezinye zezibonelelo ezizuzwe ngabasebenzisi bomhlaba ngenxa ye-biological control yezityalo ze-cactus. Nangona kunjalo kucacile ukuba ukwandisa inzame zokukhulisa nokukhupha ngobuninzi izinambuzane ezizixhobo ze-biological control kuyafuneka ukuze uMzantsi Afrika ufumane izibonelelo eziphakamileyo enokubakho ngokusetyenziswa kwe zinambuzane ezizixhobo ze-biological control zokulawula ukhula lwe-cactus olukhoyo kweli lizwe. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Date Issued: 2022-04-08
Sequence, structure, dynamics, and substrate specificity analyses of bacterial Glycoside Hydrolase 1 enzymes from several activities
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
Singlet oxygen and optical limiting applications of BODIPYs and other molecular dyes
- Authors: May, Aviwe Khanya
- Date: 2022-04-08
- Subjects: Dyes and dyeing Chemistry , Phthalocyanines , Photochemotherapy , Active oxygen , Nonlinear optics , Time-dependent density functional theory , Photochemistry
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294618 , vital:57238 , DOI 10.21504/10962/294620
- Description: A series of structurally diverse novel and previously synthesized BODIPY core dyes are synthesized and characterized in this thesis. These BODIPYs were synthesized using 2-methylpyrrole, 2-ethylpyrrole, 2,4-dimethylpyrrole and 3-ethyl-2,4-dimethylpyrrole as the starting pyrroles. The combination of different pyrroles with the same aldehyde results in BODIPY core dyes that are structural analogues. These core dyes were used as precursors to synthesise halogenated BODIPYs and novel styrylBODIPY dyes, which were successfully characterized using FT-IR and 1H NMR spectroscopy. The halogenated BODIPY core dyes and the styrylBODIPY dyes were also characterized using MALDI-TOF mass spectrometry. The introduction of heavy atoms on the BODIPY core leads to a red shift of the main spectral. In the presence of styryl groups, the main spectral band red shifts to the far red end of the visible region. As expected, the halogenated BODIPY core dyes also had moderate singlet oxygen quantum yields. These halogenated core dyes were found to be suitable as photosensitizers as all the dyes reduced bacterial viability to below 50% during photodynamic antimicrobial chemotherapy (PACT) studies against Staphylococcus aureus. The structure-property relationships studied demonstrate that the presence of protons rather than methyls at the 1,7-positions or iodines at the 2,6-positions results in more favorable PACT activity. This is likely to be related to the greater ability of the meso-aryl to rotate into the plane of the dipyrromethene ligand and suggests that there should be a stronger focus on dyes of this type in future studies in this field. During nonlinear optical (NLO) studies, all the styrylBODIPYs exhibited favorable reverse saturable absorption (RSA) responses. In the absence of methyl groups at the 1,7-positions, the meso-aryl ring lies closer to the π-system of the BODIPY core, enhancing donor (D)–π–acceptor (A) properties and resulting in slightly enhanced optical limiting (OL) parameters. Additionally, there is no evidence that the introduction of heavy atoms at the 2,6-positions significantly enhances OL properties. In a similar manner, alkyl substituents at these positions also do not significantly enhance OL properties; this was studied for the first time using 15 with ethyl groups at the 2,6-positions. The combination of z-scan data and transient spectroscopy for 16 demonstrated that the main mechanism responsible for the NLO properties of nonhalogenated BODIPY dyes is one-photon absorption from the ground state followed by ESA in the singlet manifold. From the NLO studies of 25, OL parameters of 1,3,5-tristyrylBODIPY dyes were found to be similar in magnitude to properties of distyrylBODIPY dyes, but to have less favorable optical properties for OL applications. The OL properties of scandium phthalocyanines were assessed for the first time, since the Sc(III) ion, unusually for a first row transition metal ion, is known to readily form sandwich complexes. The presence of a Sc(III) ion does not significantly enhance the OL properties of phthalocyanines relative to those of rare earth metal ions that also form complexes of this type. Because BODIPYs and phthalocyanines typically absorb significantly in the visible region, transparent PBC polymer thin films of disilane-bridged compounds with minimal absorption in this region were studied and exhibited an excellent RSA response. These compounds may be useful in the design of OL materials that can protect the human eye. The optimized geometries and spectroscopic properties of selected BODIPYs were studied. As expected, the presence of bromine, iodine, ethyl and styryl groups at different positions of the BODIPY core leads to a narrowing of the HOMO–LUMO band gap, which results in a red-shift of the main spectral band. Partial atomic charges have also been calculated for some of the styrylBODIPY dyes studied for application in OL, and electrostatic potential energy maps were also visualized to better assess how the dipole moment of BODIPY dyes can be modulated since this can affect the OL properties. For all the BODIPYs studied, the electronegativity of the atoms present influences charge distribution on the BODIPY structure. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: May, Aviwe Khanya
- Date: 2022-04-08
- Subjects: Dyes and dyeing Chemistry , Phthalocyanines , Photochemotherapy , Active oxygen , Nonlinear optics , Time-dependent density functional theory , Photochemistry
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294618 , vital:57238 , DOI 10.21504/10962/294620
- Description: A series of structurally diverse novel and previously synthesized BODIPY core dyes are synthesized and characterized in this thesis. These BODIPYs were synthesized using 2-methylpyrrole, 2-ethylpyrrole, 2,4-dimethylpyrrole and 3-ethyl-2,4-dimethylpyrrole as the starting pyrroles. The combination of different pyrroles with the same aldehyde results in BODIPY core dyes that are structural analogues. These core dyes were used as precursors to synthesise halogenated BODIPYs and novel styrylBODIPY dyes, which were successfully characterized using FT-IR and 1H NMR spectroscopy. The halogenated BODIPY core dyes and the styrylBODIPY dyes were also characterized using MALDI-TOF mass spectrometry. The introduction of heavy atoms on the BODIPY core leads to a red shift of the main spectral. In the presence of styryl groups, the main spectral band red shifts to the far red end of the visible region. As expected, the halogenated BODIPY core dyes also had moderate singlet oxygen quantum yields. These halogenated core dyes were found to be suitable as photosensitizers as all the dyes reduced bacterial viability to below 50% during photodynamic antimicrobial chemotherapy (PACT) studies against Staphylococcus aureus. The structure-property relationships studied demonstrate that the presence of protons rather than methyls at the 1,7-positions or iodines at the 2,6-positions results in more favorable PACT activity. This is likely to be related to the greater ability of the meso-aryl to rotate into the plane of the dipyrromethene ligand and suggests that there should be a stronger focus on dyes of this type in future studies in this field. During nonlinear optical (NLO) studies, all the styrylBODIPYs exhibited favorable reverse saturable absorption (RSA) responses. In the absence of methyl groups at the 1,7-positions, the meso-aryl ring lies closer to the π-system of the BODIPY core, enhancing donor (D)–π–acceptor (A) properties and resulting in slightly enhanced optical limiting (OL) parameters. Additionally, there is no evidence that the introduction of heavy atoms at the 2,6-positions significantly enhances OL properties. In a similar manner, alkyl substituents at these positions also do not significantly enhance OL properties; this was studied for the first time using 15 with ethyl groups at the 2,6-positions. The combination of z-scan data and transient spectroscopy for 16 demonstrated that the main mechanism responsible for the NLO properties of nonhalogenated BODIPY dyes is one-photon absorption from the ground state followed by ESA in the singlet manifold. From the NLO studies of 25, OL parameters of 1,3,5-tristyrylBODIPY dyes were found to be similar in magnitude to properties of distyrylBODIPY dyes, but to have less favorable optical properties for OL applications. The OL properties of scandium phthalocyanines were assessed for the first time, since the Sc(III) ion, unusually for a first row transition metal ion, is known to readily form sandwich complexes. The presence of a Sc(III) ion does not significantly enhance the OL properties of phthalocyanines relative to those of rare earth metal ions that also form complexes of this type. Because BODIPYs and phthalocyanines typically absorb significantly in the visible region, transparent PBC polymer thin films of disilane-bridged compounds with minimal absorption in this region were studied and exhibited an excellent RSA response. These compounds may be useful in the design of OL materials that can protect the human eye. The optimized geometries and spectroscopic properties of selected BODIPYs were studied. As expected, the presence of bromine, iodine, ethyl and styryl groups at different positions of the BODIPY core leads to a narrowing of the HOMO–LUMO band gap, which results in a red-shift of the main spectral band. Partial atomic charges have also been calculated for some of the styrylBODIPY dyes studied for application in OL, and electrostatic potential energy maps were also visualized to better assess how the dipole moment of BODIPY dyes can be modulated since this can affect the OL properties. For all the BODIPYs studied, the electronegativity of the atoms present influences charge distribution on the BODIPY structure. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
Structural determinants of the HSP90-Fibronectin interaction and implications for fibrillogenesis
- Authors: Chakraborty, Abir
- Date: 2022-04-08
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/294572 , vital:57234
- Description: Thesis embargoed. Release date April 2024. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Chakraborty, Abir
- Date: 2022-04-08
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/294572 , vital:57234
- Description: Thesis embargoed. Release date April 2024. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
Synthesis and evaluation of the medicinal potential of novel 4-hydroxycoumarin derivatives
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164458 , vital:41120 , doi:10.21504/10962/164458
- Description: This research has focused on the synthesis and biological evaluation of a broad range of compounds characterised by the presence of the pharmacologically significant 4-hydroxycoumalin scaffold. The compounds were designed to contain additional pharmachophoric centres to enhance bioactivity and generate lead compounds with dualaction potential. The use of 4-hydroxycoumarin as the primary synthon enabled access to various series of 4-hydroxycoumarin conjugates, the reactive 3-position on the 4-hydroxycoumarin moiety being exploited for regioselective construction of the targeted compounds in several steps. Some of the reactants required in the construction of these compounds were specially synthesised and included propargyloxy benzaldehydes, benzyloxy benzaldehydes and 2,3-dihydroxysuccino-dihydride. Overall, eight different families of novel compounds were accessed, comprising conjugates of 4-hydroxycoumarin with bisethylidenesuccinohyrazide, trifluoroacetamide, amino, benzyloxyphenyl-iminoethyl, benzylidenehyrazinyl-thiazoyl, benzylidenehydrazonoethyl, propargyloxybenzylidenehydrazonoethyl and phenylacryloyl moieties using protocols that required minimal work-up and purification. The eighty novel compounds synthesised in the study were fully characterised using HMRS and advanced NMR techniques. Cytotoxicity, HIV-1 IN and PR inhibitory, and antitrypanosomal, antimalarial and anti-Mtb assays were conducted on the synthesised coumarin derivatives. Several compounds exhibited activity against HIV-1 IN, the most potent being a bis-ethylidenesuccinohyrazide with an IC50 value of 3.5 μM. Various compounds exhibited anti-malarial activity (% pLDH viability in the range 62-77%), anti-trypanosomal activity (the most potent with an IC50 = 0.9 μM against T.b. brucei) and a measure of anti-Mtb activity. Apart from two chalconyl derivatives, none of the synthesised compounds exhibited significant cytotoxicity. Conflicting results were obtained from the in silico docking studies; in some cases supporting the observed in vitro assay data while, in others, exhibiting no correlation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2022-04-08
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164458 , vital:41120 , doi:10.21504/10962/164458
- Description: This research has focused on the synthesis and biological evaluation of a broad range of compounds characterised by the presence of the pharmacologically significant 4-hydroxycoumalin scaffold. The compounds were designed to contain additional pharmachophoric centres to enhance bioactivity and generate lead compounds with dualaction potential. The use of 4-hydroxycoumarin as the primary synthon enabled access to various series of 4-hydroxycoumarin conjugates, the reactive 3-position on the 4-hydroxycoumarin moiety being exploited for regioselective construction of the targeted compounds in several steps. Some of the reactants required in the construction of these compounds were specially synthesised and included propargyloxy benzaldehydes, benzyloxy benzaldehydes and 2,3-dihydroxysuccino-dihydride. Overall, eight different families of novel compounds were accessed, comprising conjugates of 4-hydroxycoumarin with bisethylidenesuccinohyrazide, trifluoroacetamide, amino, benzyloxyphenyl-iminoethyl, benzylidenehyrazinyl-thiazoyl, benzylidenehydrazonoethyl, propargyloxybenzylidenehydrazonoethyl and phenylacryloyl moieties using protocols that required minimal work-up and purification. The eighty novel compounds synthesised in the study were fully characterised using HMRS and advanced NMR techniques. Cytotoxicity, HIV-1 IN and PR inhibitory, and antitrypanosomal, antimalarial and anti-Mtb assays were conducted on the synthesised coumarin derivatives. Several compounds exhibited activity against HIV-1 IN, the most potent being a bis-ethylidenesuccinohyrazide with an IC50 value of 3.5 μM. Various compounds exhibited anti-malarial activity (% pLDH viability in the range 62-77%), anti-trypanosomal activity (the most potent with an IC50 = 0.9 μM against T.b. brucei) and a measure of anti-Mtb activity. Apart from two chalconyl derivatives, none of the synthesised compounds exhibited significant cytotoxicity. Conflicting results were obtained from the in silico docking studies; in some cases supporting the observed in vitro assay data while, in others, exhibiting no correlation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2022-04-08
The characterization of GTP Cyclohydrolase I and 6-Pyruvoyl Tetrahydropterin Synthase enzymes as potential anti-malarial drug targets
- Khairallah, Afrah Yousif Huseein
- Authors: Khairallah, Afrah Yousif Huseein
- Date: 2022-04-08
- Subjects: Antimalarials , Plasmodium falciparum , Malaria Chemotherapy , Malaria Africa , Drug resistance , Drug development , Molecular dynamics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233784 , vital:50127 , DOI 10.21504/10962/233784
- Description: Malaria remains a public health problem and a high burden of disease, especially in developing countries. The unicellular protozoan malaria parasite of the genus Plasmodium infects about a quarter of a billion people annually, with an estimated 409 000 death cases. The majority of malaria cases occurred in Africa; hence, the region is regarded as endemic for malaria. Global efforts to eradicate the disease led to a decrease in morbidity and mortality rates. However, an enormous burden of malaria infection remains, and it cannot go unnoticed. Countries with limited resources are more affected by the disease, mainly on its public health and socio-economic development, due to many factors besides malaria itself, such as lack of access to adequate, affordable treatments and preventative regimes. Furthermore, the current antimalarial drugs are losing their efficacy because of parasite drug resistance. The emerged drug resistance has reduced the drug efficacy in clearing the parasite from the host system, causing prolonged illness and a higher risk of death. Therefore, the emerged antimalarial drug resistance has hindered the global efforts for malaria control and elimination and established an urgent need for new treatment strategies. When the resistance against classical antimalarial drugs emerged, the class of antifolate antimalarial medicines became the most common alternative. The antifolate antimalarial drugs target the malaria parasite de novo folate biosynthesis pathway by limiting folate derivates, which are essential for the parasite cell growth and survival. Yet again, the malaria parasite developed resistance against the available antifolate drugs, rendering the drugs ineffective in many cases. Given the previous success in targeting the malaria parasite de novo folate biosynthesis pathway, alternative enzymes within this pathway stand as good targets and can be explored to develop new antifolate drugs with novel mechanisms of action. The primary focus of this thesis is to contribute to the existing and growing knowledge of antimalarial drug discovery. The study aims to characterise the malaria parasite de novo folate synthesis pathway enzymes guanosine-5'-triphosphate (GTP) cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS) as alternative drug targets for malaria treatment by using computational approaches. Further, discover new allosteric drug targeting sites within the two enzymes' 3D structures for future drug design and discovery. Sequence and structural analysis were carried out to characterise and pinpoint the two enzymes' unique sequence and structure-based features. From the analyses, key sequence and structure differences were identified between the malaria parasite enzymes relative to their human homolog; the identified sites can aid significantly in designing and developing new antimalarial antifolate drugs with good selectivity toward the parasites’ enzymes. GCH1 and PTPS contain a catalytically essential metal ion in their active site; therefore, force field parameters were needed to study their active sites accurately during all-atom molecular dynamic simulations (MD). The force field parameters were derived through quantum mechanics potential energy surface scans of the metals bonded terms and evaluated via all-atom MD simulations. Proteins structural dynamics is imperative for many biological processes; thus, it is essential to consider the structural dynamics of proteins whilst understanding their function. In this regard, the normal mode analysis (NMA) approach based on the elastic network model (ENM) was employed to study the intrinsic dynamics and conformations changes of GCH1 and PTPS enzymes. The NMA disclosed essential structural information about the protein’s intrinsic dynamics and mechanism of allosteric modulation of their binding properties, further highlighting regions that govern their conformational changes. The analysis also disclosed hotspot residues that are crucial for the proteins' fold stability and function. The NMA was further combined with sequence motif results and showed that conserved residues of GCH1 and PTPS were located within the identified key structural sites modulating the proteins' conformational rearrangement. The characterized structural features and hotspot residues were regarded as potential allosteric sites of important value for the design and development of allosteric drugs. Both GCH1 and PTPS enzymes have never been targeted before and can provide an excellent opportunity to overcome the antimalarial antifolate drug resistance problem. The data presented in this thesis contribute to the understanding of the sequence, structure, and global dynamics of both GCH1 and PTPS, further disclose potential allosteric drug targeting sites and unique structural features of both enzymes that can establish a solid starting point for drug design and development of new antimalarial drugs of a novel mechanism of actions. Lastly, the reported force field parameters will be of value for MD simulations for future in-silico drug discovery studies involving the two enzymes and other enzymes with the same Zn2+ binding motifs and coordination environments. The impact of this research can facilitate the discovery of new effective antimalarial medicines with novel mechanisms of action. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Khairallah, Afrah Yousif Huseein
- Date: 2022-04-08
- Subjects: Antimalarials , Plasmodium falciparum , Malaria Chemotherapy , Malaria Africa , Drug resistance , Drug development , Molecular dynamics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233784 , vital:50127 , DOI 10.21504/10962/233784
- Description: Malaria remains a public health problem and a high burden of disease, especially in developing countries. The unicellular protozoan malaria parasite of the genus Plasmodium infects about a quarter of a billion people annually, with an estimated 409 000 death cases. The majority of malaria cases occurred in Africa; hence, the region is regarded as endemic for malaria. Global efforts to eradicate the disease led to a decrease in morbidity and mortality rates. However, an enormous burden of malaria infection remains, and it cannot go unnoticed. Countries with limited resources are more affected by the disease, mainly on its public health and socio-economic development, due to many factors besides malaria itself, such as lack of access to adequate, affordable treatments and preventative regimes. Furthermore, the current antimalarial drugs are losing their efficacy because of parasite drug resistance. The emerged drug resistance has reduced the drug efficacy in clearing the parasite from the host system, causing prolonged illness and a higher risk of death. Therefore, the emerged antimalarial drug resistance has hindered the global efforts for malaria control and elimination and established an urgent need for new treatment strategies. When the resistance against classical antimalarial drugs emerged, the class of antifolate antimalarial medicines became the most common alternative. The antifolate antimalarial drugs target the malaria parasite de novo folate biosynthesis pathway by limiting folate derivates, which are essential for the parasite cell growth and survival. Yet again, the malaria parasite developed resistance against the available antifolate drugs, rendering the drugs ineffective in many cases. Given the previous success in targeting the malaria parasite de novo folate biosynthesis pathway, alternative enzymes within this pathway stand as good targets and can be explored to develop new antifolate drugs with novel mechanisms of action. The primary focus of this thesis is to contribute to the existing and growing knowledge of antimalarial drug discovery. The study aims to characterise the malaria parasite de novo folate synthesis pathway enzymes guanosine-5'-triphosphate (GTP) cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS) as alternative drug targets for malaria treatment by using computational approaches. Further, discover new allosteric drug targeting sites within the two enzymes' 3D structures for future drug design and discovery. Sequence and structural analysis were carried out to characterise and pinpoint the two enzymes' unique sequence and structure-based features. From the analyses, key sequence and structure differences were identified between the malaria parasite enzymes relative to their human homolog; the identified sites can aid significantly in designing and developing new antimalarial antifolate drugs with good selectivity toward the parasites’ enzymes. GCH1 and PTPS contain a catalytically essential metal ion in their active site; therefore, force field parameters were needed to study their active sites accurately during all-atom molecular dynamic simulations (MD). The force field parameters were derived through quantum mechanics potential energy surface scans of the metals bonded terms and evaluated via all-atom MD simulations. Proteins structural dynamics is imperative for many biological processes; thus, it is essential to consider the structural dynamics of proteins whilst understanding their function. In this regard, the normal mode analysis (NMA) approach based on the elastic network model (ENM) was employed to study the intrinsic dynamics and conformations changes of GCH1 and PTPS enzymes. The NMA disclosed essential structural information about the protein’s intrinsic dynamics and mechanism of allosteric modulation of their binding properties, further highlighting regions that govern their conformational changes. The analysis also disclosed hotspot residues that are crucial for the proteins' fold stability and function. The NMA was further combined with sequence motif results and showed that conserved residues of GCH1 and PTPS were located within the identified key structural sites modulating the proteins' conformational rearrangement. The characterized structural features and hotspot residues were regarded as potential allosteric sites of important value for the design and development of allosteric drugs. Both GCH1 and PTPS enzymes have never been targeted before and can provide an excellent opportunity to overcome the antimalarial antifolate drug resistance problem. The data presented in this thesis contribute to the understanding of the sequence, structure, and global dynamics of both GCH1 and PTPS, further disclose potential allosteric drug targeting sites and unique structural features of both enzymes that can establish a solid starting point for drug design and development of new antimalarial drugs of a novel mechanism of actions. Lastly, the reported force field parameters will be of value for MD simulations for future in-silico drug discovery studies involving the two enzymes and other enzymes with the same Zn2+ binding motifs and coordination environments. The impact of this research can facilitate the discovery of new effective antimalarial medicines with novel mechanisms of action. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
The role of angling-guides in promoting pro-environmental catch-and-release attitudes and behaviours in the recreational angling community
- Authors: Farthing, Matthew William
- Date: 2022-04-08
- Subjects: Fishing , Fishing Catch effort , Fishing guides , Fishers , Human behavior , Role models
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294583 , vital:57235 , DOI 10.21504/10962/294585
- Description: Angling-guides are respected as opinion leaders of the recreational angling community, but nothing is known of their influence on angler behaviour. Given their social-standing, angling-guides may be perceived as role-models by angling-clients – thereby promoting the adoption of best and/or poor catch-and-release (C&R) practices, depending on their individual knowledge, attitudes and behaviour. It is critical to understand their potential influence, their knowledge and their behaviours to inform effective intervention strategies which could exploit their extensive networking potential. The aim of this thesis was to better understand the potential utility of angling-guides in efforts to improve angler behaviour. Firstly, this was done by investigating whether angling-guides are perceived as role-models by angling-clients (Chapter 2). Secondly, it was done by assessing the current level of knowledge, attitudes and behaviours of angling-guides from around the world (Chapter 3). Thirdly, it was done by exploring the relationship between angling-guide knowledge, attitudes, intentions and actual behaviour in a case-study of guided-angling trips (Chapter 4). Lastly, it was done by exploring intervention frameworks and incorporating insights into potential strategies for promoting pro-environmental angling behaviours to angling-guides (Chapter 5). To understand if angling-guides are perceived as role-models by the recreational angling community (Chapter 2), a digital survey was designed to assess previous angling-clients’ attitudes towards angling-guides serving the three role-model functions proposed in the Motivational Theory of Role-Modelling, namely as Behavioural models, Representations of the Possible and Inspiration. Of the 492 angling-clients (27 countries), most agreed that angling-guides were competent, skilled, and worth emulating (91.1%), suggesting they are perceived as Behavioural Models. Less agreed that angling-guides were Inspirational or Representations of the Possible (54.8%), suggesting they are less likely to motivate anglers to adopt and/or pursue new goals. As Behavioural Models, angling-guide C&R practices are likely to be emulated, which is of both utility and concern to managers. As angling-guides are likely to be emulated, a digital survey was designed to assess their knowledge, attitudes and behaviours (particularly C&R best-practices) (Chapter 3). Of the 342 angling-guides (47 countries), few had accredited training (9.4%). However, most were deemed “knowledgeable of best-practices” (69.0%), but pervasive misconceptions of key C&R best-practices were observed. Attitudes towards best-practices were generally pro-environmental, and those deemed knowledgeable had significantly more pro-environmental attitudes (p = 0.003). Most angling-guides had pro-environmental attitudes towards their environmental responsibilities (87.1 - 89.5%), but these broad attitudes cannot predict specific pro-environmental behaviours during guided-angling trips where angler satisfaction is often at odds with best-practice. Angling-client satisfaction has important financial implications for angling-guides, and even those with pro-environmental intentions may struggle to adhere to C&R best-practices with inherent sacrifices for the angling-client’s enjoyment. Observation of behaviour in context is critical for understanding the behaviour to be changed. To explore the relationship between angling-guide knowledge, intentions and actual behaviour (Chapter 4), five angling-guides were observed (and filmed) interacting with groups of angling-clients during their guided-angling trips over a 30 day period. Five angling behaviours of interest were identified, and a survey focussed on these behaviours was disseminated (18 months later) to the five angling-guides previously observed to assess their knowledge, attitudes, reported behaviours and perceptions of the norm. Generally the subjects’ reported behaviours aligned well with their knowledge of best-practice, but their actual behaviour was not well aligned (24.4%). Instead, their actual behaviour aligned better with their perceptions of the norm (80.9%), which was generally a “worse” practice than what they reported. Angling-guides appeared to favour client-satisfaction over pro-environmental behaviour. Gaps between angling-guides’ knowledge of best-practice and their actual behaviour indicate that there may be obscure and complex barriers to pro-environmental angling-guide behaviour. Many barriers are seemingly impossible to overcome, such as economic limitations and financial disincentives. These barriers may limit the efficacy of traditional knowledge-attitude-behaviour (KAB) change interventions. The strong alignment of angling-guide behaviour with social norms, and the strong community orientation of recreational angling suggests that the Community-Based Social Marketing (CBSM) approach may be a more effective framework for interventions that aim to promote pro-environmental catch-and-release behaviours at angling-guide level. The CBSM approach allows interventionists to leverage a larger suite of cognitive biases than KAB approaches, provided that sufficient understanding of the context, barriers and benefits for a given segment of the angling-guide community (likely defined by style-of-participation) are obtained. Furthermore, the success of the CBSM approach will depend on the ability of interventionists to effectively recruit and incentivise disjunct and isolated communities of angling-guides to participate in training and workshops in order to achieve the important in-person contact on which the CBSM approach depends. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Farthing, Matthew William
- Date: 2022-04-08
- Subjects: Fishing , Fishing Catch effort , Fishing guides , Fishers , Human behavior , Role models
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294583 , vital:57235 , DOI 10.21504/10962/294585
- Description: Angling-guides are respected as opinion leaders of the recreational angling community, but nothing is known of their influence on angler behaviour. Given their social-standing, angling-guides may be perceived as role-models by angling-clients – thereby promoting the adoption of best and/or poor catch-and-release (C&R) practices, depending on their individual knowledge, attitudes and behaviour. It is critical to understand their potential influence, their knowledge and their behaviours to inform effective intervention strategies which could exploit their extensive networking potential. The aim of this thesis was to better understand the potential utility of angling-guides in efforts to improve angler behaviour. Firstly, this was done by investigating whether angling-guides are perceived as role-models by angling-clients (Chapter 2). Secondly, it was done by assessing the current level of knowledge, attitudes and behaviours of angling-guides from around the world (Chapter 3). Thirdly, it was done by exploring the relationship between angling-guide knowledge, attitudes, intentions and actual behaviour in a case-study of guided-angling trips (Chapter 4). Lastly, it was done by exploring intervention frameworks and incorporating insights into potential strategies for promoting pro-environmental angling behaviours to angling-guides (Chapter 5). To understand if angling-guides are perceived as role-models by the recreational angling community (Chapter 2), a digital survey was designed to assess previous angling-clients’ attitudes towards angling-guides serving the three role-model functions proposed in the Motivational Theory of Role-Modelling, namely as Behavioural models, Representations of the Possible and Inspiration. Of the 492 angling-clients (27 countries), most agreed that angling-guides were competent, skilled, and worth emulating (91.1%), suggesting they are perceived as Behavioural Models. Less agreed that angling-guides were Inspirational or Representations of the Possible (54.8%), suggesting they are less likely to motivate anglers to adopt and/or pursue new goals. As Behavioural Models, angling-guide C&R practices are likely to be emulated, which is of both utility and concern to managers. As angling-guides are likely to be emulated, a digital survey was designed to assess their knowledge, attitudes and behaviours (particularly C&R best-practices) (Chapter 3). Of the 342 angling-guides (47 countries), few had accredited training (9.4%). However, most were deemed “knowledgeable of best-practices” (69.0%), but pervasive misconceptions of key C&R best-practices were observed. Attitudes towards best-practices were generally pro-environmental, and those deemed knowledgeable had significantly more pro-environmental attitudes (p = 0.003). Most angling-guides had pro-environmental attitudes towards their environmental responsibilities (87.1 - 89.5%), but these broad attitudes cannot predict specific pro-environmental behaviours during guided-angling trips where angler satisfaction is often at odds with best-practice. Angling-client satisfaction has important financial implications for angling-guides, and even those with pro-environmental intentions may struggle to adhere to C&R best-practices with inherent sacrifices for the angling-client’s enjoyment. Observation of behaviour in context is critical for understanding the behaviour to be changed. To explore the relationship between angling-guide knowledge, intentions and actual behaviour (Chapter 4), five angling-guides were observed (and filmed) interacting with groups of angling-clients during their guided-angling trips over a 30 day period. Five angling behaviours of interest were identified, and a survey focussed on these behaviours was disseminated (18 months later) to the five angling-guides previously observed to assess their knowledge, attitudes, reported behaviours and perceptions of the norm. Generally the subjects’ reported behaviours aligned well with their knowledge of best-practice, but their actual behaviour was not well aligned (24.4%). Instead, their actual behaviour aligned better with their perceptions of the norm (80.9%), which was generally a “worse” practice than what they reported. Angling-guides appeared to favour client-satisfaction over pro-environmental behaviour. Gaps between angling-guides’ knowledge of best-practice and their actual behaviour indicate that there may be obscure and complex barriers to pro-environmental angling-guide behaviour. Many barriers are seemingly impossible to overcome, such as economic limitations and financial disincentives. These barriers may limit the efficacy of traditional knowledge-attitude-behaviour (KAB) change interventions. The strong alignment of angling-guide behaviour with social norms, and the strong community orientation of recreational angling suggests that the Community-Based Social Marketing (CBSM) approach may be a more effective framework for interventions that aim to promote pro-environmental catch-and-release behaviours at angling-guide level. The CBSM approach allows interventionists to leverage a larger suite of cognitive biases than KAB approaches, provided that sufficient understanding of the context, barriers and benefits for a given segment of the angling-guide community (likely defined by style-of-participation) are obtained. Furthermore, the success of the CBSM approach will depend on the ability of interventionists to effectively recruit and incentivise disjunct and isolated communities of angling-guides to participate in training and workshops in order to achieve the important in-person contact on which the CBSM approach depends. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
The systematic assembly of prostate specific antigen electrochemical sensors based on asymmetric Co(II) phthalocyanines, graphitic quantum dots and an aptamer
- Authors: Nxele, Siphesihle Robin
- Date: 2022-04-08
- Subjects: Prostate-specific antigen , Electrochemical sensors , Phthalocyanines , Quantum dots , Co(II) phthalocyanines , Aptamer
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232893 , vital:50035 , DOI 10.21504/10962/232893
- Description: The need for low-cost, efficient and simple diagnostic tools has led to more research going into this subject, with the aim of making such medical devices more accessible where they are needed. This has led to more researchers developing point-of-care devices for this purpose worldwide, by sensor fabrication. This thesis focuses on electrochemical sensor development for the early diagnosis of prostate cancer. It is common knowledge that prostate cancer is one of the most prevalent carcinomas that have claimed lives due to late diagnosis where even the most invasive treatments have failed. For this reason, development of early detection devices that can even be used in the comfort of home is necessary and quite crucial. Electrochemical sensors have gained much attention due to their ease of fabrication, cost effectiveness, simplicity, ease of use and high efficiency. Using nanocomposites as modifiers has also become popular as they provide greater stability and improve detection limits when used together with biomolecules. With that said, the work reported herein has combined nanocomposites of graphenebased quantum dots, gold nanoparticles, phthalocyanines and an aptamer in order to fabricate aptasensors for the electrochemical detection of prostate cancer biomarker. The aptamer is specifically designed to bind to the biomarker, and the nanocomposites are expected to enhance current output thus lowering detection limits and increasing stability and efficiency. Reproducible results are also expected. Prior to the detection of the prostate cancer biomarker, the quantum dots-phthalocyanine nanohybrids were used to detect L-cysteine, which is an amino acid, in order to verify the synergistic effects as electrode modifiers that lead to the enhancement of current output. This increase in current output is then v exploited for the improvement of aptasensor functionality upon incorporation of the aptamer, for the detection of prostate specific antigen. The research in this thesis has been carried out with the intention of contributing to the world of medical research, more so because of the ever-increasing need for medical care to become accessible to all and not only to those who can afford expensive technologies and treatments. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Nxele, Siphesihle Robin
- Date: 2022-04-08
- Subjects: Prostate-specific antigen , Electrochemical sensors , Phthalocyanines , Quantum dots , Co(II) phthalocyanines , Aptamer
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232893 , vital:50035 , DOI 10.21504/10962/232893
- Description: The need for low-cost, efficient and simple diagnostic tools has led to more research going into this subject, with the aim of making such medical devices more accessible where they are needed. This has led to more researchers developing point-of-care devices for this purpose worldwide, by sensor fabrication. This thesis focuses on electrochemical sensor development for the early diagnosis of prostate cancer. It is common knowledge that prostate cancer is one of the most prevalent carcinomas that have claimed lives due to late diagnosis where even the most invasive treatments have failed. For this reason, development of early detection devices that can even be used in the comfort of home is necessary and quite crucial. Electrochemical sensors have gained much attention due to their ease of fabrication, cost effectiveness, simplicity, ease of use and high efficiency. Using nanocomposites as modifiers has also become popular as they provide greater stability and improve detection limits when used together with biomolecules. With that said, the work reported herein has combined nanocomposites of graphenebased quantum dots, gold nanoparticles, phthalocyanines and an aptamer in order to fabricate aptasensors for the electrochemical detection of prostate cancer biomarker. The aptamer is specifically designed to bind to the biomarker, and the nanocomposites are expected to enhance current output thus lowering detection limits and increasing stability and efficiency. Reproducible results are also expected. Prior to the detection of the prostate cancer biomarker, the quantum dots-phthalocyanine nanohybrids were used to detect L-cysteine, which is an amino acid, in order to verify the synergistic effects as electrode modifiers that lead to the enhancement of current output. This increase in current output is then v exploited for the improvement of aptasensor functionality upon incorporation of the aptamer, for the detection of prostate specific antigen. The research in this thesis has been carried out with the intention of contributing to the world of medical research, more so because of the ever-increasing need for medical care to become accessible to all and not only to those who can afford expensive technologies and treatments. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
The transformative potential of intersecting arts-based inquiry and environmental learning in urban South Africa: a focus on socio-ecological water pedagogies
- Authors: James, Anna Katharine
- Date: 2022-04-08
- Subjects: Environmental education South Africa , Water conservation Study and teaching South Africa , Art in environmental education South Africa , Social learning South Africa , Educational sociology South Africa , Water-supply Social aspects South Africa , Critical realism , Socio-ecological education
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/290660 , vital:56772 , DOI 10.21504/10962/290660
- Description: In this study I explore and explain transformative potential in arts-based environmental learning with a focus on water pedagogy. The study took place over a period of four years, where approximately 40 school pupils between the ages of 10 and 17 years-old were engaged in participatory arts-based inquiries into water located across unequal neighbourhoods in Cape Town, South Africa. Educators, school learners, citizens and decision-makers hold different historical, cultural, political and spiritual perspectives on water. These play a role in shaping what is termed in this research the ‘hydro-social cycle’. Yet, due to dominant ideas of what counts as knowing and truth, educators in educational settings struggle to account for the complexity of water, limiting educational encounters to a partial knowing leading mostly to limited unimaginative framings of problems and solutions. My focus on transformative potential in learning is derived from a concern for how environmental education encounters and the sense-making they enable, are infused by socio-economic, political, and historical elements, specifically colonialism, capitalism, and white supremacist racism. The connections between the multiple layers of capitalist crisis and the ever-urgent environmental crisis are not adequately made in mainstream forms of water education. The research explores how arts-based pedagogy could enable a productive meeting of critical environmental education with ecological literacies. Within this positioning, transformative potential considers how educational engagements position questions about water within the social life of participants/learners and inform learning that leads to fuller and more nuanced greater knowledge. Theoretically, I work with an interrogation of critical education theory, underlaboured by critical realism which enabled me to rigorously consider how claims to knowing are shaped by their accompanying assumptions of what is real. Drawing on recent debates in critical education theory, I resist the notion of critique as ideology and engage instead in the craftsmanship of contextual and responsive inquiry practice. This has enabled me to articulate processes and relationships in water education encounters with meaningful understandings of the effects of simultaneous crises rooted in racial capitalism and environmental crisis. My methodological approach is arts-based educational research with a directive to reflect upon educational encounters in an integrated way. It includes two parts informing the facilitation and analysis of open-ended learning processes. One component was arts-based inquiry practice developed for exploring complexity, drawing on the thinking of Norris (2009, 2011) and Finley (2016, 2017). The second part holds reflective space for these encounters guided by the practice of pedagogical narration inspired by the Reggio Amelia approach, demonstrated by Pacini-Ketchabaw, Nxumalo, Kocher, Elliot and Sanchez (2014). Clarifying the intellectual work of a responsive educator-researcher, pedagogical narration brings multiple theoretical lenses into conversation with emergent dimensions of educational process. In practice, in order to transgress the dominance of colonial white supremacist knowledge frames of water, I needed to be curious, to be confounded, to expect the unexpected in the educational encounters with participants and this mirroring of practice was emulated by the participants as they followed their own questions about water in Mzansi (South Africa). In our work together we came up against assumptions we had previously not questioned as individuals. Together we explored the implications of this by, for example, questioning who is responsible for saving water. These explorations required bringing together science knowledge and everyday knowledge at multiple scales: the household, catchment, government and global. It required us to be critical of how language and images are mobilized in public communication and school curriculums; for example, representations of water are infused with history and power in a way that impacts how we know and teach about water. The transformative potential of this pedagogical space is generated through acts of creative expression which are seen as acts of absenting absence, for example exhibiting through play how water use in the household interconnects with gender and age relationships. As such, creative expression through multiple mediums or more-than-text enables a deeper understanding of water as well as openings for interdisciplinary engagement with learning about water. My research found that in bringing together the contributions of critical education and environmental education in practice, two shifts are needed: environmental educators need to view ecological literacy as inseparable from the social and political. The knowledge that is shared about water in the classroom has social and political implications. On the other hand, critical educators need to better locate justice concerns in the material and ecological world at scale. Arts-based inquiry, as a kind of scaffolding for pedagogical process, has the potential to enable these shifts by opening up fixed analytical frames. Making these shifts requires a reflective practice on the part of the educator to navigate the inherited blind spots in environmental learning and critical education, such as dualities. One way to do this is for the educator to identify absences, as articulated in the Critical Realist tradition, and consider how these absences might be absented. This differs from a simplistic process of critique in the possibilities it opens up for collaboration between different schools of thought rather than further polarisation and alienation between educators and knowledge keepers on social ecologies. These insights have relevance for many sites of environmental education practice, such as natural science lecturers, school teachers or community activists. It is knowledge-learning work emergent from and responsive to complex ecological crisis, which requires everyone to rethink and open up to new ways of being, seeing and doing around these issues. The transformative potential of this work is that the thinking and transforming at all scales can be catalysed and grounded through the arts based educational encounters with the participants. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: James, Anna Katharine
- Date: 2022-04-08
- Subjects: Environmental education South Africa , Water conservation Study and teaching South Africa , Art in environmental education South Africa , Social learning South Africa , Educational sociology South Africa , Water-supply Social aspects South Africa , Critical realism , Socio-ecological education
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/290660 , vital:56772 , DOI 10.21504/10962/290660
- Description: In this study I explore and explain transformative potential in arts-based environmental learning with a focus on water pedagogy. The study took place over a period of four years, where approximately 40 school pupils between the ages of 10 and 17 years-old were engaged in participatory arts-based inquiries into water located across unequal neighbourhoods in Cape Town, South Africa. Educators, school learners, citizens and decision-makers hold different historical, cultural, political and spiritual perspectives on water. These play a role in shaping what is termed in this research the ‘hydro-social cycle’. Yet, due to dominant ideas of what counts as knowing and truth, educators in educational settings struggle to account for the complexity of water, limiting educational encounters to a partial knowing leading mostly to limited unimaginative framings of problems and solutions. My focus on transformative potential in learning is derived from a concern for how environmental education encounters and the sense-making they enable, are infused by socio-economic, political, and historical elements, specifically colonialism, capitalism, and white supremacist racism. The connections between the multiple layers of capitalist crisis and the ever-urgent environmental crisis are not adequately made in mainstream forms of water education. The research explores how arts-based pedagogy could enable a productive meeting of critical environmental education with ecological literacies. Within this positioning, transformative potential considers how educational engagements position questions about water within the social life of participants/learners and inform learning that leads to fuller and more nuanced greater knowledge. Theoretically, I work with an interrogation of critical education theory, underlaboured by critical realism which enabled me to rigorously consider how claims to knowing are shaped by their accompanying assumptions of what is real. Drawing on recent debates in critical education theory, I resist the notion of critique as ideology and engage instead in the craftsmanship of contextual and responsive inquiry practice. This has enabled me to articulate processes and relationships in water education encounters with meaningful understandings of the effects of simultaneous crises rooted in racial capitalism and environmental crisis. My methodological approach is arts-based educational research with a directive to reflect upon educational encounters in an integrated way. It includes two parts informing the facilitation and analysis of open-ended learning processes. One component was arts-based inquiry practice developed for exploring complexity, drawing on the thinking of Norris (2009, 2011) and Finley (2016, 2017). The second part holds reflective space for these encounters guided by the practice of pedagogical narration inspired by the Reggio Amelia approach, demonstrated by Pacini-Ketchabaw, Nxumalo, Kocher, Elliot and Sanchez (2014). Clarifying the intellectual work of a responsive educator-researcher, pedagogical narration brings multiple theoretical lenses into conversation with emergent dimensions of educational process. In practice, in order to transgress the dominance of colonial white supremacist knowledge frames of water, I needed to be curious, to be confounded, to expect the unexpected in the educational encounters with participants and this mirroring of practice was emulated by the participants as they followed their own questions about water in Mzansi (South Africa). In our work together we came up against assumptions we had previously not questioned as individuals. Together we explored the implications of this by, for example, questioning who is responsible for saving water. These explorations required bringing together science knowledge and everyday knowledge at multiple scales: the household, catchment, government and global. It required us to be critical of how language and images are mobilized in public communication and school curriculums; for example, representations of water are infused with history and power in a way that impacts how we know and teach about water. The transformative potential of this pedagogical space is generated through acts of creative expression which are seen as acts of absenting absence, for example exhibiting through play how water use in the household interconnects with gender and age relationships. As such, creative expression through multiple mediums or more-than-text enables a deeper understanding of water as well as openings for interdisciplinary engagement with learning about water. My research found that in bringing together the contributions of critical education and environmental education in practice, two shifts are needed: environmental educators need to view ecological literacy as inseparable from the social and political. The knowledge that is shared about water in the classroom has social and political implications. On the other hand, critical educators need to better locate justice concerns in the material and ecological world at scale. Arts-based inquiry, as a kind of scaffolding for pedagogical process, has the potential to enable these shifts by opening up fixed analytical frames. Making these shifts requires a reflective practice on the part of the educator to navigate the inherited blind spots in environmental learning and critical education, such as dualities. One way to do this is for the educator to identify absences, as articulated in the Critical Realist tradition, and consider how these absences might be absented. This differs from a simplistic process of critique in the possibilities it opens up for collaboration between different schools of thought rather than further polarisation and alienation between educators and knowledge keepers on social ecologies. These insights have relevance for many sites of environmental education practice, such as natural science lecturers, school teachers or community activists. It is knowledge-learning work emergent from and responsive to complex ecological crisis, which requires everyone to rethink and open up to new ways of being, seeing and doing around these issues. The transformative potential of this work is that the thinking and transforming at all scales can be catalysed and grounded through the arts based educational encounters with the participants. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
The use of smartphones and visualisation processes for conceptual understanding of mensuration: a case study of the Mathcitymap Project in Namibia
- Authors: Shimakeleni, Liina
- Date: 2022-04-08
- Subjects: Mathematics Study and teaching (Secondary) Namibia Oshana , Smartphones , Visual learning , Measurement , Concept learning , MathCityMap (MCM) project
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290649 , vital:56771
- Description: The aim of this study was to investigate and analyse the potential use of smartphones as visualisation tools by learners to enhance conceptual understanding through mathematics trails developed using the MathCityMap (MCM) project. This research study is part of the VIPROmaths project which seeks to research the effective use of visualisation processes in mathematics classrooms in South Africa, Namibia, Zambia, Switzerland and Germany. This study adopted a case of twelve purposively selected Grade 9 learners from a school in the Eheke circuit of the Oshana region, Namibia. This study was framed within a social constructivist perspective and sought to investigate visualisation processes as well as conceptual understanding of learners as they conceptualised the MCM tasks in new, outdoor and collaborative learning situations. The MCM app was installed on selected learners’ smartphones to access and to walk the MCM trails located in various places in the schoolyard. Three MCM trails based on three key themes of mensuration (perimeter, area and volume) were created. Each consisted of four tasks that were sourced and developed in line with the Grade 9 Namibian mathematics syllabus. This study is oriented in an interpretive paradigm and employed video-recorded observations and focus group interviews as qualitative data collection methods. Data collected were analysed first using the themes developed from Ho’s (2010) work on visualisation processes and Kilpatrick, Swafford, and Findell’s (2001) conceptual understanding. During analysis, some themes emerged from the data and were considered. Findings from this study revealed that smartphones afforded learners ample opportunities to enhance the visualisation processes that they went through as they learned the concepts of measurement. In addition to this, some learners were initially pessimistic regarding the use of smartphones for learning purposes. This study recommends that resources such as MCM be effectively be used in formal school settings. The learning of measurement can be advanced in outdoor settings where learners have physical and spatial access to the learning content. Smartphone technology can be used as an additional tool to integrate Information and Communication Technology (ICT) in learning mathematics within the Namibian context. , Thesis (MED) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Shimakeleni, Liina
- Date: 2022-04-08
- Subjects: Mathematics Study and teaching (Secondary) Namibia Oshana , Smartphones , Visual learning , Measurement , Concept learning , MathCityMap (MCM) project
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290649 , vital:56771
- Description: The aim of this study was to investigate and analyse the potential use of smartphones as visualisation tools by learners to enhance conceptual understanding through mathematics trails developed using the MathCityMap (MCM) project. This research study is part of the VIPROmaths project which seeks to research the effective use of visualisation processes in mathematics classrooms in South Africa, Namibia, Zambia, Switzerland and Germany. This study adopted a case of twelve purposively selected Grade 9 learners from a school in the Eheke circuit of the Oshana region, Namibia. This study was framed within a social constructivist perspective and sought to investigate visualisation processes as well as conceptual understanding of learners as they conceptualised the MCM tasks in new, outdoor and collaborative learning situations. The MCM app was installed on selected learners’ smartphones to access and to walk the MCM trails located in various places in the schoolyard. Three MCM trails based on three key themes of mensuration (perimeter, area and volume) were created. Each consisted of four tasks that were sourced and developed in line with the Grade 9 Namibian mathematics syllabus. This study is oriented in an interpretive paradigm and employed video-recorded observations and focus group interviews as qualitative data collection methods. Data collected were analysed first using the themes developed from Ho’s (2010) work on visualisation processes and Kilpatrick, Swafford, and Findell’s (2001) conceptual understanding. During analysis, some themes emerged from the data and were considered. Findings from this study revealed that smartphones afforded learners ample opportunities to enhance the visualisation processes that they went through as they learned the concepts of measurement. In addition to this, some learners were initially pessimistic regarding the use of smartphones for learning purposes. This study recommends that resources such as MCM be effectively be used in formal school settings. The learning of measurement can be advanced in outdoor settings where learners have physical and spatial access to the learning content. Smartphone technology can be used as an additional tool to integrate Information and Communication Technology (ICT) in learning mathematics within the Namibian context. , Thesis (MED) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
Towards the Common Good: An expansive post-abyssal (Re)stor(y)ing of the epistemic cultures of the citizen sciences
- Authors: Vallabh, Priya
- Date: 2022-04-08
- Subjects: Science Citizen participation , Decolonization , Social epistemology , Hegemony , Common good , Traditional ecological knowledge , Ethnoscience
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/290671 , vital:56773 , DOI 10.21504/10962/290671
- Description: In this study I explore and explain transformatiThe citizen sciences convene complex and reflexive ecologies of knowledges in response to a range of social-ecological risks. Their epistemic cultures seem to be assembled in ways which increase potential mobilisation of the common knowledges being produced, thereby producing knowledges in forms that are more strongly aligned with a range of implementation strategies. However, much of such processes of knowledge production have been ‘cleaned out’ of official accounts through scientifically hegemonic systems of legitimation, deepening hegemonically-entrenched systems of epistemic, contributory and distributive injustices, and undermining the potential for stronger enactments of participatory and radical democracies. The engagement of sociologies of absences and emergences in this study evidence these epistemic insights, thereby evidencing an expansive post-abyssal (re)stor(y)ing of the citizen sciences. Through this research, I consider knowledge production as ‘commoning', towards the constitution of the common good. To date, most accounts of knowledge production within citizen science projects primarily focus on scientific processes of knowledge production and legitimation. Such accounts neglect the ecologies of diverse knowledges through which knowledge is being collaboratively produced, the forms of learning that occur, or the ways in which such ecologies are mobilised in response to specific socialecological risks. To better understand the ways in which citizen science projects build risk-responsive common knowledge, I bring a focus to the diversity of epistemic cultures convened, speaking to this gap. My primary research question is: How do the epistemic cultures within citizen science projects enable commoning in response to social-ecological risk? To begin, I establish a particular vantage point from which the remainder of the thesis is launched, one which centres as the primary interest of knowledge production, an interest in social-ecological justice and the constitution of the common good. From this vantage point, knowledge co-production and learning can be viewed as acts of commoning, which themselves constitute common goods. I draw on the work of Karin Knorr Cetina to conceptualise and frame notions of epistemic cultures and their epistemic features. Expanding notions of epistemic cultures from a post-abyssal perspective, I draw on the work of Bruno Latour and Boaventura de Sousa Santos. Latour’s distinctions between the production of ‘matters of fact’ and ‘matters of concern’ provide a way to challenge hegemonic systems of scientific knowledge production, while preserving the potential emergence of multiplicity in the context of evolving risk, thereby enabling a greater degree of situated reflexivity. Santos argues for the reclamation of all ways of knowing, including but not limited to scientific ways of knowing the world. He argues that other forms of knowledge are produced as nonexistent, and that they might be reclaimed through engaging sociologies of absences and emergences. Both authors enable a stronger analysis of knowledge production in terms of its ability to intervene into context in response to manifest risks. These three theoretical approaches are convened into an analytical framework for the study. To enact sociologies of absences and emergences, I engage two forms of immanent critique, complemented by an epistemic mapping of 50 South African citizen science projects, and an analysis of three illustrative case studies. The first critique is one of produced nonexistence, through which I consider three aspects of the general knowledge cultures within which the epistemic cultures of citizen science projects are situated. This critique makes evident the ways in which the ontological and related conceptual structures of hegemonic scientific knowledge production actively produce as nonexistent, other onto-epistemic contributions to knowledge production in response to social-ecological risks. The second critique reviews the field of peer-reviewed literature through a reading of presence and absence, with a focus on the articulation of epistemic cultures. Predictably, a key finding is that this form of scientific reporting primarily foregrounds legitimated scientifically processed knowledge, while once again producing as nonexistent, other forms of knowledges. However, there is evidence of increasing accounts of citizen science which recognise both a diversity of knowledge contributions, and epistemic, contributory and distributive justice issues as regards hegemonic forms of reporting. The epistemic mapping evidences a highly diversified field of citizen sciences, whose epistemic cultures are convened to produce distinct forms of scientifically-informed knowledges in response to diverse contexts, scales and notions of risk. The three illustrative case studies engage sociologies of absences and emergences, with particular focus on articulating the ecologies of knowledges evidenced in project documentation, including both official and unofficial accounts of epistemic activity. This analysis highlights the significant contributions of diverse forms of knowledges, including scientific, situated, embodied, governance, indigenous, spiritual and relational knowledges, and the ways in which these knowledge are convened to respond to specific configurations of risk. It once again highlights issues of epistemic, contributory and distributive justice, and makes evident the need for stronger integrity in processes of producing and reporting common knowledges. The case studies also illustrate the increased effectiveness of leveraging an ecology of knowledges (in contrast to a monoculture of scientific knowledge) in response to situated risks, including how such ecologies have a tendency to be generative and enable multiple forms of intervention into structures and applied contexts of intervention. In response to the collective research findings, a think-piece on rigour-as-integrity is offered as a contribution to commoning, in response to social-ecological risk. The piece draws together a postabyssal system of rigour intended to strengthen knowledge production in ways which actively centre forms of justice and commoning. ve potential in arts-based environmental learning with a focus on water pedagogy. The study took place over a period of four years, where approximately 40 school pupils between the ages of 10 and 17 years-old were engaged in participatory arts-based inquiries into water located across unequal neighbourhoods in Cape Town, South Africa. Educators, school learners, citizens and decision-makers hold different historical, cultural, political and spiritual perspectives on water. These play a role in shaping what is termed in this research the ‘hydro-social cycle’. Yet, due to dominant ideas of what counts as knowing and truth, educators in educational settings struggle to account for the complexity of water, limiting educational encounters to a partial knowing leading mostly to limited unimaginative framings of problems and solutions. My focus on transformative potential in learning is derived from a concern for how environmental education encounters and the sense-making they enable, are infused by socio-economic, political, and historical elements, specifically colonialism, capitalism, and white supremacist racism. The connections between the multiple layers of capitalist crisis and the ever-urgent environmental crisis are not adequately made in mainstream forms of water education. The research explores how arts-based pedagogy could enable a productive meeting of critical environmental education with ecological literacies. Within this positioning, transformative potential considers how educational engagements position questions about water within the social life of participants/learners and inform learning that leads to fuller and more nuanced greater knowledge. Theoretically, I work with an interrogation of critical education theory, underlaboured by critical realism which enabled me to rigorously consider how claims to knowing are shaped by their accompanying assumptions of what is real. Drawing on recent debates in critical education theory, I resist the notion of critique as ideology and engage instead in the craftsmanship of contextual and responsive inquiry practice. This has enabled me to articulate processes and relationships in water education encounters with meaningful understandings of the effects of simultaneous crises rooted in racial capitalism and environmental crisis. My methodological approach is arts-based educational research with a directive to reflect upon educational encounters in an integrated way. It includes two parts informing the facilitation and analysis of open-ended learning processes. One component was arts-based inquiry practice developed for exploring complexity, drawing on the thinking of Norris (2009, 2011) and Finley (2016, 2017). The second part holds reflective space for these encounters guided by the practice of pedagogical narration inspired by the Reggio Amelia approach, demonstrated by Pacini-Ketchabaw, Nxumalo, Kocher, Elliot and Sanchez (2014). Clarifying the intellectual work of a responsive educator-researcher, pedagogical narration brings multiple theoretical lenses into conversation with emergent dimensions of educational process. In practice, in order to transgress the dominance of colonial white supremacist knowledge frames of water, I needed to be curious, to be confounded, to expect the unexpected in the educational encounters with participants and this mirroring of practice was emulated by the participants as they followed their own questions about water in Mzansi (South Africa). In our work together we came up against assumptions we had previously not questioned as individuals. Together we explored the implications of this by, for example, questioning who is responsible for saving water. These explorations required bringing together science knowledge and everyday knowledge at multiple scales: the household, catchment, government and global. It required us to be critical of how language and images are mobilized in public communication and school curriculums; for example, representations of water are infused with history and power in a way that impacts how we know and teach about water. The transformative potential of this pedagogical space is generated through acts of creative expression which are seen as acts of absenting absence, for example exhibiting through play how water use in the household interconnects with gender and age relationships. As such, creative expression through multiple mediums or more-than-text enables a deeper understanding of water as well as openings for interdisciplinary engagement with learning about water. My research found that in bringing together the contributions of critical education and environmental education in practice, two shifts are needed: environmental educators need to view ecological literacy as inseparable from the social and political. The knowledge that is shared about water in the classroom has social and political implications. On the other hand, critical educators need to better locate justice concerns in the material and ecological world at scale. Arts-based inquiry, as a kind of scaffolding for pedagogical process, has the potential to enable these shifts by opening up fixed analytical frames. Making these shifts requires a reflective practice on the part of the educator to navigate the inherited blind spots in environmental learning and critical education, such as dualities. One way to do this is for the educator to identify absences, as articulated in the Critical Realist tradition, and consider how these absences might be absented. This differs from a simplistic process of critique in the possibilities it opens up for collaboration between different schools of thought rather than further polarisation and alienation between educators and knowledge keepers on social ecologies. These insights have relevance for many sites of environmental education practice, such as natural science lecturers, school teachers or community activists. It is knowledge-learning work emergent from and responsive to complex ecological crisis, which requires everyone to rethink and open up to new ways of being, seeing and doing around these issues. The transformative potential of this work is that the thinking and transforming at all scales can be catalysed and grounded through the arts based educational encounters with the participants. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Vallabh, Priya
- Date: 2022-04-08
- Subjects: Science Citizen participation , Decolonization , Social epistemology , Hegemony , Common good , Traditional ecological knowledge , Ethnoscience
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/290671 , vital:56773 , DOI 10.21504/10962/290671
- Description: In this study I explore and explain transformatiThe citizen sciences convene complex and reflexive ecologies of knowledges in response to a range of social-ecological risks. Their epistemic cultures seem to be assembled in ways which increase potential mobilisation of the common knowledges being produced, thereby producing knowledges in forms that are more strongly aligned with a range of implementation strategies. However, much of such processes of knowledge production have been ‘cleaned out’ of official accounts through scientifically hegemonic systems of legitimation, deepening hegemonically-entrenched systems of epistemic, contributory and distributive injustices, and undermining the potential for stronger enactments of participatory and radical democracies. The engagement of sociologies of absences and emergences in this study evidence these epistemic insights, thereby evidencing an expansive post-abyssal (re)stor(y)ing of the citizen sciences. Through this research, I consider knowledge production as ‘commoning', towards the constitution of the common good. To date, most accounts of knowledge production within citizen science projects primarily focus on scientific processes of knowledge production and legitimation. Such accounts neglect the ecologies of diverse knowledges through which knowledge is being collaboratively produced, the forms of learning that occur, or the ways in which such ecologies are mobilised in response to specific socialecological risks. To better understand the ways in which citizen science projects build risk-responsive common knowledge, I bring a focus to the diversity of epistemic cultures convened, speaking to this gap. My primary research question is: How do the epistemic cultures within citizen science projects enable commoning in response to social-ecological risk? To begin, I establish a particular vantage point from which the remainder of the thesis is launched, one which centres as the primary interest of knowledge production, an interest in social-ecological justice and the constitution of the common good. From this vantage point, knowledge co-production and learning can be viewed as acts of commoning, which themselves constitute common goods. I draw on the work of Karin Knorr Cetina to conceptualise and frame notions of epistemic cultures and their epistemic features. Expanding notions of epistemic cultures from a post-abyssal perspective, I draw on the work of Bruno Latour and Boaventura de Sousa Santos. Latour’s distinctions between the production of ‘matters of fact’ and ‘matters of concern’ provide a way to challenge hegemonic systems of scientific knowledge production, while preserving the potential emergence of multiplicity in the context of evolving risk, thereby enabling a greater degree of situated reflexivity. Santos argues for the reclamation of all ways of knowing, including but not limited to scientific ways of knowing the world. He argues that other forms of knowledge are produced as nonexistent, and that they might be reclaimed through engaging sociologies of absences and emergences. Both authors enable a stronger analysis of knowledge production in terms of its ability to intervene into context in response to manifest risks. These three theoretical approaches are convened into an analytical framework for the study. To enact sociologies of absences and emergences, I engage two forms of immanent critique, complemented by an epistemic mapping of 50 South African citizen science projects, and an analysis of three illustrative case studies. The first critique is one of produced nonexistence, through which I consider three aspects of the general knowledge cultures within which the epistemic cultures of citizen science projects are situated. This critique makes evident the ways in which the ontological and related conceptual structures of hegemonic scientific knowledge production actively produce as nonexistent, other onto-epistemic contributions to knowledge production in response to social-ecological risks. The second critique reviews the field of peer-reviewed literature through a reading of presence and absence, with a focus on the articulation of epistemic cultures. Predictably, a key finding is that this form of scientific reporting primarily foregrounds legitimated scientifically processed knowledge, while once again producing as nonexistent, other forms of knowledges. However, there is evidence of increasing accounts of citizen science which recognise both a diversity of knowledge contributions, and epistemic, contributory and distributive justice issues as regards hegemonic forms of reporting. The epistemic mapping evidences a highly diversified field of citizen sciences, whose epistemic cultures are convened to produce distinct forms of scientifically-informed knowledges in response to diverse contexts, scales and notions of risk. The three illustrative case studies engage sociologies of absences and emergences, with particular focus on articulating the ecologies of knowledges evidenced in project documentation, including both official and unofficial accounts of epistemic activity. This analysis highlights the significant contributions of diverse forms of knowledges, including scientific, situated, embodied, governance, indigenous, spiritual and relational knowledges, and the ways in which these knowledge are convened to respond to specific configurations of risk. It once again highlights issues of epistemic, contributory and distributive justice, and makes evident the need for stronger integrity in processes of producing and reporting common knowledges. The case studies also illustrate the increased effectiveness of leveraging an ecology of knowledges (in contrast to a monoculture of scientific knowledge) in response to situated risks, including how such ecologies have a tendency to be generative and enable multiple forms of intervention into structures and applied contexts of intervention. In response to the collective research findings, a think-piece on rigour-as-integrity is offered as a contribution to commoning, in response to social-ecological risk. The piece draws together a postabyssal system of rigour intended to strengthen knowledge production in ways which actively centre forms of justice and commoning. ve potential in arts-based environmental learning with a focus on water pedagogy. The study took place over a period of four years, where approximately 40 school pupils between the ages of 10 and 17 years-old were engaged in participatory arts-based inquiries into water located across unequal neighbourhoods in Cape Town, South Africa. Educators, school learners, citizens and decision-makers hold different historical, cultural, political and spiritual perspectives on water. These play a role in shaping what is termed in this research the ‘hydro-social cycle’. Yet, due to dominant ideas of what counts as knowing and truth, educators in educational settings struggle to account for the complexity of water, limiting educational encounters to a partial knowing leading mostly to limited unimaginative framings of problems and solutions. My focus on transformative potential in learning is derived from a concern for how environmental education encounters and the sense-making they enable, are infused by socio-economic, political, and historical elements, specifically colonialism, capitalism, and white supremacist racism. The connections between the multiple layers of capitalist crisis and the ever-urgent environmental crisis are not adequately made in mainstream forms of water education. The research explores how arts-based pedagogy could enable a productive meeting of critical environmental education with ecological literacies. Within this positioning, transformative potential considers how educational engagements position questions about water within the social life of participants/learners and inform learning that leads to fuller and more nuanced greater knowledge. Theoretically, I work with an interrogation of critical education theory, underlaboured by critical realism which enabled me to rigorously consider how claims to knowing are shaped by their accompanying assumptions of what is real. Drawing on recent debates in critical education theory, I resist the notion of critique as ideology and engage instead in the craftsmanship of contextual and responsive inquiry practice. This has enabled me to articulate processes and relationships in water education encounters with meaningful understandings of the effects of simultaneous crises rooted in racial capitalism and environmental crisis. My methodological approach is arts-based educational research with a directive to reflect upon educational encounters in an integrated way. It includes two parts informing the facilitation and analysis of open-ended learning processes. One component was arts-based inquiry practice developed for exploring complexity, drawing on the thinking of Norris (2009, 2011) and Finley (2016, 2017). The second part holds reflective space for these encounters guided by the practice of pedagogical narration inspired by the Reggio Amelia approach, demonstrated by Pacini-Ketchabaw, Nxumalo, Kocher, Elliot and Sanchez (2014). Clarifying the intellectual work of a responsive educator-researcher, pedagogical narration brings multiple theoretical lenses into conversation with emergent dimensions of educational process. In practice, in order to transgress the dominance of colonial white supremacist knowledge frames of water, I needed to be curious, to be confounded, to expect the unexpected in the educational encounters with participants and this mirroring of practice was emulated by the participants as they followed their own questions about water in Mzansi (South Africa). In our work together we came up against assumptions we had previously not questioned as individuals. Together we explored the implications of this by, for example, questioning who is responsible for saving water. These explorations required bringing together science knowledge and everyday knowledge at multiple scales: the household, catchment, government and global. It required us to be critical of how language and images are mobilized in public communication and school curriculums; for example, representations of water are infused with history and power in a way that impacts how we know and teach about water. The transformative potential of this pedagogical space is generated through acts of creative expression which are seen as acts of absenting absence, for example exhibiting through play how water use in the household interconnects with gender and age relationships. As such, creative expression through multiple mediums or more-than-text enables a deeper understanding of water as well as openings for interdisciplinary engagement with learning about water. My research found that in bringing together the contributions of critical education and environmental education in practice, two shifts are needed: environmental educators need to view ecological literacy as inseparable from the social and political. The knowledge that is shared about water in the classroom has social and political implications. On the other hand, critical educators need to better locate justice concerns in the material and ecological world at scale. Arts-based inquiry, as a kind of scaffolding for pedagogical process, has the potential to enable these shifts by opening up fixed analytical frames. Making these shifts requires a reflective practice on the part of the educator to navigate the inherited blind spots in environmental learning and critical education, such as dualities. One way to do this is for the educator to identify absences, as articulated in the Critical Realist tradition, and consider how these absences might be absented. This differs from a simplistic process of critique in the possibilities it opens up for collaboration between different schools of thought rather than further polarisation and alienation between educators and knowledge keepers on social ecologies. These insights have relevance for many sites of environmental education practice, such as natural science lecturers, school teachers or community activists. It is knowledge-learning work emergent from and responsive to complex ecological crisis, which requires everyone to rethink and open up to new ways of being, seeing and doing around these issues. The transformative potential of this work is that the thinking and transforming at all scales can be catalysed and grounded through the arts based educational encounters with the participants. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04-08