Nonlinear optical behavior of lanthanide phthalocyanines and their conjugates with a selection of nanomaterials
- Authors: Sekhosana, Kutloano Edward
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4580 , vital:20695
- Description: This thesis presents novel asymmetrical and symmetrical lanthanide phthalocyanines (Pcs) characterized using a number techniques including proton nuclear magnetic resonance, electron spin resonance, time correlated single photon counting, FTIR spectrometry, MALDI-TOF mass spectrometry, UV-Vis spectrometry, Raman spectroscopy and CHNS elemental analysis. The design of theses lanthanide Pcs takes the form of mononuclear, binuclear, trinuclear, bis- and tris(phthalocyanines). Nanomaterials such as zinc oxide nanoparticles (ZnO NPs), multi-walled carbon nanotubes (MWCNTs) and graphene oxide nanosheets (GONS) (oxidized and reduced) were employed for covalent linkage to mono- and binuclear phthalocyanines as conjugates. Transmission electron microscopy was used to characterize ZnO NPs, MWCNTs and GONS alone and when linked to lanthanide Pcs. Lanthanide Pcs alone and when linked to ZnO NPs, MWCNTs and GONS where embedded in polymers such as poly (methyl methacrylate) (PMMA), poly (bisphenol A carbonate) (PBC) and poly (acrylic acid) (PAA) for thin film preparation. The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction (XRD). Optical limiting properties of lanthanide Pcs alone and as conjugates in solution and when incorporated into polymers were determined by employing a Z-scan technique. It emerged that low symmetry lanthanide Pcs (19, 20 and 21), the blue forms of bis(phthalocyanines) (only in solution; 24 and 28) as well as tris(phthalocyanines) (30 and 31) exhibit low limiting threshold (Ilim) values in solution and thin films (particularly PBC and PAA). The low limiting threshold values make these lanthanide Pcs reliable optical limiters.
- Full Text:
- Authors: Sekhosana, Kutloano Edward
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4580 , vital:20695
- Description: This thesis presents novel asymmetrical and symmetrical lanthanide phthalocyanines (Pcs) characterized using a number techniques including proton nuclear magnetic resonance, electron spin resonance, time correlated single photon counting, FTIR spectrometry, MALDI-TOF mass spectrometry, UV-Vis spectrometry, Raman spectroscopy and CHNS elemental analysis. The design of theses lanthanide Pcs takes the form of mononuclear, binuclear, trinuclear, bis- and tris(phthalocyanines). Nanomaterials such as zinc oxide nanoparticles (ZnO NPs), multi-walled carbon nanotubes (MWCNTs) and graphene oxide nanosheets (GONS) (oxidized and reduced) were employed for covalent linkage to mono- and binuclear phthalocyanines as conjugates. Transmission electron microscopy was used to characterize ZnO NPs, MWCNTs and GONS alone and when linked to lanthanide Pcs. Lanthanide Pcs alone and when linked to ZnO NPs, MWCNTs and GONS where embedded in polymers such as poly (methyl methacrylate) (PMMA), poly (bisphenol A carbonate) (PBC) and poly (acrylic acid) (PAA) for thin film preparation. The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction (XRD). Optical limiting properties of lanthanide Pcs alone and as conjugates in solution and when incorporated into polymers were determined by employing a Z-scan technique. It emerged that low symmetry lanthanide Pcs (19, 20 and 21), the blue forms of bis(phthalocyanines) (only in solution; 24 and 28) as well as tris(phthalocyanines) (30 and 31) exhibit low limiting threshold (Ilim) values in solution and thin films (particularly PBC and PAA). The low limiting threshold values make these lanthanide Pcs reliable optical limiters.
- Full Text:
Nonlinear optical responses of phthalocyanines in the presence of nanomaterials or when embedded in polymeric materials
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
Nontsizi Mgqwetho’s the nation’s bounty: a prophetic voice towards an African literary theory
- Authors: Nxasana, Thulani
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4547 , vital:20687
- Description: This thesis seeks to examine the ways in which Africans and African scholarship in particular have relied on the West to lead the way in scientific inquiry, theory and ways of approaching literary texts thus the stunting effects of this in the growth and development of uniquely African literary scholarship and theorising. In his seminal work, Decolonising the Mind, Wa Thiong’o (1987a) stresses that “...how we view ourselves, our environment even, is very much dependent on where we stand in relationship to imperialism in its colonial and neocolonial stages; that if we are to do anything about our individual and collective being today, then we have to coldly and consciously look at what imperialism has been doing to us and to our view of ourselves in the universe” (Wa Thiong’o, 1987a, p.88). Although most African countries obtained their liberation decades ago, seemingly western cultural imperialism still dominates and plagues the African psyche; hence they largely look to the West and ways of the West for established and emergent theoretical conceptions. This thesis aims to interrogate popular western literary theories unquestioningly used to analyse African works, particularly feminism and post-colonial theory; furthermore, to show crucial factors not taken into account such as the evolving power dynamics in African societies, the role of the “sacred” or spirituality which often forms and informs the dynamics of the text, and lastly, based on the poetry of Nontsizi Mgqwetho, to advocate for the need for an African literary theory and put forward the essential tenets of such a theory. The poetry of Xhosa poet, Nontsizi Mgqwetho, is used to analyse the complexities and dynamics of African literary production written in African languages; her poetry is written in isiXhosa to a Xhosa audience, a far cry from the assumption that African literary texts are concerned with writing to the “centre” as post-colonial theorists claim. Her work explicitly provides Africans with an approach to overcome territorial and cultural imperialism; she sees within the African psyche and traditional values empowering modes of resistance against any type of domination and through her poetry illustrates meaningful ways that Africans can critically engage with and examine the positives and negatives of cultural exchange and or assimilation, and the effects thereof while at the same time remaining proudly Africa.
- Full Text:
- Authors: Nxasana, Thulani
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4547 , vital:20687
- Description: This thesis seeks to examine the ways in which Africans and African scholarship in particular have relied on the West to lead the way in scientific inquiry, theory and ways of approaching literary texts thus the stunting effects of this in the growth and development of uniquely African literary scholarship and theorising. In his seminal work, Decolonising the Mind, Wa Thiong’o (1987a) stresses that “...how we view ourselves, our environment even, is very much dependent on where we stand in relationship to imperialism in its colonial and neocolonial stages; that if we are to do anything about our individual and collective being today, then we have to coldly and consciously look at what imperialism has been doing to us and to our view of ourselves in the universe” (Wa Thiong’o, 1987a, p.88). Although most African countries obtained their liberation decades ago, seemingly western cultural imperialism still dominates and plagues the African psyche; hence they largely look to the West and ways of the West for established and emergent theoretical conceptions. This thesis aims to interrogate popular western literary theories unquestioningly used to analyse African works, particularly feminism and post-colonial theory; furthermore, to show crucial factors not taken into account such as the evolving power dynamics in African societies, the role of the “sacred” or spirituality which often forms and informs the dynamics of the text, and lastly, based on the poetry of Nontsizi Mgqwetho, to advocate for the need for an African literary theory and put forward the essential tenets of such a theory. The poetry of Xhosa poet, Nontsizi Mgqwetho, is used to analyse the complexities and dynamics of African literary production written in African languages; her poetry is written in isiXhosa to a Xhosa audience, a far cry from the assumption that African literary texts are concerned with writing to the “centre” as post-colonial theorists claim. Her work explicitly provides Africans with an approach to overcome territorial and cultural imperialism; she sees within the African psyche and traditional values empowering modes of resistance against any type of domination and through her poetry illustrates meaningful ways that Africans can critically engage with and examine the positives and negatives of cultural exchange and or assimilation, and the effects thereof while at the same time remaining proudly Africa.
- Full Text:
Physical organic studies of substituted norbornyl systems: aspects of mechanisms and chirality
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
Pushing the bounds of possibility: South African academics narrate their experiences of having agency to effect transformation
- Authors: Idahosa, Grace Ese-Osa
- Date: 2017
- Subjects: Education, Higher -- South Africa , Education, Higher -- Social aspects -- South Africa , Educational change -- South Africa , Higher education and state -- South Africa , Rhodes University
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5845 , vital:20981
- Description: Over 20 years after the first democratic elections, the institutional cultures and structures of many South African universities remain un-transformed; they are embedded with racist and sexist discourses and attitudes that allow for the marginalisation and exclusion of students and staff (Department of Education 2008; Soudien 2010; van Wyk and Alexander 2010; Akoojee and Nkomo 2007; Hemson and Singh 2010). In order to effect change, research has noted the importance of leadership and staff involvement in the transformation process (Van-Der Westhuizen 2006; Portnoi 2009; Niemann 2010; Viljoen and Rothmann 2002). These studies argue that both leaders and staff members must be interested, and actively involved in, the transformation process. This suggests that the extent to which leaders and individual staff members have agency to effect transformatory practices determines the success of transformation policies. But what motivates this interest in transformation? While a number of studies have focused on the imperative to transform, few studies have focused on the role of individual agency in the transformation process. After all the world and in some ways structural properties are given to us and at the same time ‘actively constituted by us’ (van Manen 1997, XI). Drawing on interviews with academic staff members at one university in South Africa, this study uses a hermeneutic phenomenological approach to understand the nature of having agency to enable transformation drawing on the experiences of academic staff members. In the context of studies on the agency- structure divide and the need for a structural and cultural change in universities in South Africa, the project aimed to find out how transformation happens, when it does happen. I was interested in how individual agents are able to use their agency to ensure transformation amid limiting and rigid structures and cultures in the university. Given the fact that structures are only revealed in human action, the individual experience of transformation at once gives insight into the dominant structures, the social context and how their capacity to act was deployed to enable a change in such structures - at least in their own experience and understanding. This may help our understanding of transformation and what is needed to effect the transformation of deeply embedded apartheid legacies in university structures and cultures. This study aimed to reveal moments at which individuals embedded in what have been identified as rigid structures and cultures perceive themselves as having had the agency to interrupt and transform them despite their rigid nature. The study was interested in what characterises these moments and what individual and institutional contexts make them more or less possible/likely.
- Full Text:
- Authors: Idahosa, Grace Ese-Osa
- Date: 2017
- Subjects: Education, Higher -- South Africa , Education, Higher -- Social aspects -- South Africa , Educational change -- South Africa , Higher education and state -- South Africa , Rhodes University
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5845 , vital:20981
- Description: Over 20 years after the first democratic elections, the institutional cultures and structures of many South African universities remain un-transformed; they are embedded with racist and sexist discourses and attitudes that allow for the marginalisation and exclusion of students and staff (Department of Education 2008; Soudien 2010; van Wyk and Alexander 2010; Akoojee and Nkomo 2007; Hemson and Singh 2010). In order to effect change, research has noted the importance of leadership and staff involvement in the transformation process (Van-Der Westhuizen 2006; Portnoi 2009; Niemann 2010; Viljoen and Rothmann 2002). These studies argue that both leaders and staff members must be interested, and actively involved in, the transformation process. This suggests that the extent to which leaders and individual staff members have agency to effect transformatory practices determines the success of transformation policies. But what motivates this interest in transformation? While a number of studies have focused on the imperative to transform, few studies have focused on the role of individual agency in the transformation process. After all the world and in some ways structural properties are given to us and at the same time ‘actively constituted by us’ (van Manen 1997, XI). Drawing on interviews with academic staff members at one university in South Africa, this study uses a hermeneutic phenomenological approach to understand the nature of having agency to enable transformation drawing on the experiences of academic staff members. In the context of studies on the agency- structure divide and the need for a structural and cultural change in universities in South Africa, the project aimed to find out how transformation happens, when it does happen. I was interested in how individual agents are able to use their agency to ensure transformation amid limiting and rigid structures and cultures in the university. Given the fact that structures are only revealed in human action, the individual experience of transformation at once gives insight into the dominant structures, the social context and how their capacity to act was deployed to enable a change in such structures - at least in their own experience and understanding. This may help our understanding of transformation and what is needed to effect the transformation of deeply embedded apartheid legacies in university structures and cultures. This study aimed to reveal moments at which individuals embedded in what have been identified as rigid structures and cultures perceive themselves as having had the agency to interrupt and transform them despite their rigid nature. The study was interested in what characterises these moments and what individual and institutional contexts make them more or less possible/likely.
- Full Text:
Sign language in South Africa: pedagogic approaches, policy developments and new directions
- Authors: Ganiso, Mirriam Nosiphiwo
- Date: 2017
- Subjects: Deaf -- Education -- South Africa , South African sign language -- Study and teaching , Sign language -- Study and teaching -- South Africa , Sign language -- Grammar
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7323 , vital:21242
- Description: This objective of this thesis is to present and critique sign language-in-education policy and different teaching pedagogies used by teachers in the Eastern and Western Cape Deaf schools. The research was conducted in four Deaf schools in the Eastern and Western Cape Provinces. Data was collected through methods which include interviews, observations and questionnaires. The study results revealed that there was inconsistency of teaching approaches used by teachers in these different schools because some of them lacked knowledge and sign language skills. Additionally, many teachers who are teaching in Deaf schools did not get sign language training. Thus, the study concluded that some teachers lack knowledge of teaching methods. Also Deaf schools’ principals and school governing bodies employ teachers who are coming from the mainstream and who are not necessarily aware of Deaf children’s needs, forgetting that Deaf learners will struggle without suitable resources. Furthermore, the study concluded that teachers use different teaching approaches, such as Total Communication, Oral Approach, Signed English, Bilingualism, South African Sign Language (SASL) and other means of communication. Deaf learners were also forced to use Oral Communication although some of them were totally deaf. The research showed that Deaf learners and Deaf teacher assistants were not pleased about the way Deaf learners were being taught. Deaf learners complained about teachers, that they lack sign language communication skills and as a result the learners became the interpreters for the teachers. Teachers in turn complained about the curriculum training which was provided for individual and selected teachers. The research also offers a comparative study, in the sense that the development of sign language across different countries from Europe and Africa as well as the United States of America, is included. The thesis furthermore explores the development of SASL CAPS Curriculum in the Western Cape Province, i.e. grade R-3 which began in 2014 as opposed to the Eastern Cape teachers who experienced difficulties due to limited curriculum implementation resources. Therefore, this research suggests that, the Language Task Team which worked on the new CAPS curriculum should have involved Deaf teachers and teachers more generally in their team and decisions. The research sought to find a theoretical or grammatical basis for the development of SASL, while at the same time providing empirical data gathered from the four respective school sites. This data is analysed and presented in the thesis.
- Full Text:
- Authors: Ganiso, Mirriam Nosiphiwo
- Date: 2017
- Subjects: Deaf -- Education -- South Africa , South African sign language -- Study and teaching , Sign language -- Study and teaching -- South Africa , Sign language -- Grammar
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7323 , vital:21242
- Description: This objective of this thesis is to present and critique sign language-in-education policy and different teaching pedagogies used by teachers in the Eastern and Western Cape Deaf schools. The research was conducted in four Deaf schools in the Eastern and Western Cape Provinces. Data was collected through methods which include interviews, observations and questionnaires. The study results revealed that there was inconsistency of teaching approaches used by teachers in these different schools because some of them lacked knowledge and sign language skills. Additionally, many teachers who are teaching in Deaf schools did not get sign language training. Thus, the study concluded that some teachers lack knowledge of teaching methods. Also Deaf schools’ principals and school governing bodies employ teachers who are coming from the mainstream and who are not necessarily aware of Deaf children’s needs, forgetting that Deaf learners will struggle without suitable resources. Furthermore, the study concluded that teachers use different teaching approaches, such as Total Communication, Oral Approach, Signed English, Bilingualism, South African Sign Language (SASL) and other means of communication. Deaf learners were also forced to use Oral Communication although some of them were totally deaf. The research showed that Deaf learners and Deaf teacher assistants were not pleased about the way Deaf learners were being taught. Deaf learners complained about teachers, that they lack sign language communication skills and as a result the learners became the interpreters for the teachers. Teachers in turn complained about the curriculum training which was provided for individual and selected teachers. The research also offers a comparative study, in the sense that the development of sign language across different countries from Europe and Africa as well as the United States of America, is included. The thesis furthermore explores the development of SASL CAPS Curriculum in the Western Cape Province, i.e. grade R-3 which began in 2014 as opposed to the Eastern Cape teachers who experienced difficulties due to limited curriculum implementation resources. Therefore, this research suggests that, the Language Task Team which worked on the new CAPS curriculum should have involved Deaf teachers and teachers more generally in their team and decisions. The research sought to find a theoretical or grammatical basis for the development of SASL, while at the same time providing empirical data gathered from the four respective school sites. This data is analysed and presented in the thesis.
- Full Text:
Synthesis and biological evaluation of anti-HIV-I integrase agents
- Jesumoroti, Omobolanle Janet
- Authors: Jesumoroti, Omobolanle Janet
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59215 , vital:27479
- Description: Expected release date-April 2019
- Full Text:
- Authors: Jesumoroti, Omobolanle Janet
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59215 , vital:27479
- Description: Expected release date-April 2019
- Full Text:
Synthesis of indium and lead phthalocyanine as photocatalysts for photodynamic antimicrobial chemotherapy and photo-oxidation of pollutants
- Authors: Oluwole, Oluyinka David
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5293 , vital:20805
- Full Text:
- Authors: Oluwole, Oluyinka David
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5293 , vital:20805
- Full Text:
Synthesis of indium and lead phthalocyanine as photocatalysts for photodynamic antimicrobial chemotherapy and photo-oxidation of pollutants
- Authors: Osifeko, Olawale L
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5221 , vital:20790
- Description: This thesis explores the synthesis of metallophthalocyanines as potential photosensitizers for application in photodynamic antimicrobial chemotherapy and phototransformation of environmental pollutants. The metallophthalocyanines containing amino substituent were conjugated with magnetic nanoparticle and semiconductor quantum dots via an amide bond and by chemisorption onto gold nanoparticles surface. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, fourier transform infrared (FTIR), nuclear magnetic resonance (¹H, ¹³C, and cozy of symmetrical phthalocyanine), electronic spectroscopy, as well as mass spectroscopy were employed to characterize all metallophthalocyanines. Quarternized pyridyloxy substituted phthalocyanine and asymmetric (AB3) metallophthalocyanines were embedded in electrospun polystyrene fiber. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of the compounds. There is an increase in triplet quantum yield for Pcs in the presence of gold nanoparticles (AuNPs) and semiconductor quantum dots (QDs), but not in the presence of magnetic nanoparticles (MNPs). Photodynamic inactivation of Escherichia coli with the quarternized photosensitizers at low concentrations totally inactivate the bacteria compared to non-charged photosensitiser. Also, a similar trend was observed for the magnetic nanoparticles conjugates. Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric Indium(III) phthalocyanines photosensitizers. The photooxidation reactions were compared with those of a symmetrical indium(III) phthalocyanines containing four quaternized 4-pyridyloxy substituents. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalysis. The immobilized photosensitizers possess good singlet oxygen generation potentials in aqueous media. The asymmetrical phthalocyanine containing 4-pyridylsulfanyl and one aminophenoxy showed the best photocatalytic behavior.
- Full Text:
- Authors: Osifeko, Olawale L
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5221 , vital:20790
- Description: This thesis explores the synthesis of metallophthalocyanines as potential photosensitizers for application in photodynamic antimicrobial chemotherapy and phototransformation of environmental pollutants. The metallophthalocyanines containing amino substituent were conjugated with magnetic nanoparticle and semiconductor quantum dots via an amide bond and by chemisorption onto gold nanoparticles surface. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, fourier transform infrared (FTIR), nuclear magnetic resonance (¹H, ¹³C, and cozy of symmetrical phthalocyanine), electronic spectroscopy, as well as mass spectroscopy were employed to characterize all metallophthalocyanines. Quarternized pyridyloxy substituted phthalocyanine and asymmetric (AB3) metallophthalocyanines were embedded in electrospun polystyrene fiber. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of the compounds. There is an increase in triplet quantum yield for Pcs in the presence of gold nanoparticles (AuNPs) and semiconductor quantum dots (QDs), but not in the presence of magnetic nanoparticles (MNPs). Photodynamic inactivation of Escherichia coli with the quarternized photosensitizers at low concentrations totally inactivate the bacteria compared to non-charged photosensitiser. Also, a similar trend was observed for the magnetic nanoparticles conjugates. Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric Indium(III) phthalocyanines photosensitizers. The photooxidation reactions were compared with those of a symmetrical indium(III) phthalocyanines containing four quaternized 4-pyridyloxy substituents. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalysis. The immobilized photosensitizers possess good singlet oxygen generation potentials in aqueous media. The asymmetrical phthalocyanine containing 4-pyridylsulfanyl and one aminophenoxy showed the best photocatalytic behavior.
- Full Text:
Systematics and biogeography of forest snails, chondrocyclus (mollusca: gastropoda: caenogastropoda: cyclophoridae) in Southern Africa
- Authors: Cole, Mary Louise
- Date: 2017
- Subjects: Chondrocyclus , Mollusks -- South Africa , Cyclophoridae -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4356 , vital:20651
- Description: This study presents a molecular phylogeny and systematic revision of Chondrocyclus, the major South African group of the large family of operculate terrestrial molluscs, the Cyclophoridae. Chondrocyclus snails are small gastropods found in forest and moist thicket throughout South Africa. This is the first detailed systematic treatment of a group of Cyclophoridae in mainland Africa and the first to provide molecular data. This study complements regional studies on the systematics of the family in Asia and provides comparative data for studies of higher level relationships within the Cyclophoridae. Phylogenetic reconstruction by BI and ML methods of combined and single gene datasets of 16S and CO 1 all showed Chondrocyclus to be monophyletic and recovered five well-supported clades that corresponded to groups of populations identifiable on the basis of combinations of morphological characters. Species were diagnosed morphologically and were shown to be genetically distinct lineages. Informative morphological features include shell dimensions, protoconch, periostracum, operculum, radula and penis. Two species in Afromontane regions of Zimbabwe and Malawi respectively are excluded from Chondrocyclus based on morphology and tentatively placed in Cyathopoma. Diversity recognised within the genus more than doubled, from a previous seven South African species to seventeen. Re-descriptions of established species and descriptions of new species are provided, together with photographs of morphological characteristics. New taxon names and nomenclatural acts within it are disclaimed and are therefore not available in the sense of the International Code of Zoological Nomenclature until validly published elsewhere. Several cryptic species within previously widespread “species” and unrecorded narrowly endemic species were documented. The clade consisting of populations of “Chondrocyclus isipingoensis”, now considered to be a species complex, was sister to a group containing the other four clades. The “Isipingoensis” clade occurs widely in Afromontane regions, along the Great Escarpment, and on the south-east coast. The other four clades occur from Zululand to the Cape Peninsula with a pattern of east-west lineage turnover. The biogeography of Chondrocyclus is interpreted by comparison with concordant patterns in other terrestrial molluscs and unrelated taxa with poor dispersal ability. This study complements other research on composition, spatial distribution and phylogenetic diversity of low-vagility invertebrates and expands the data available for biodiversity conservation in South Africa.
- Full Text:
- Authors: Cole, Mary Louise
- Date: 2017
- Subjects: Chondrocyclus , Mollusks -- South Africa , Cyclophoridae -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4356 , vital:20651
- Description: This study presents a molecular phylogeny and systematic revision of Chondrocyclus, the major South African group of the large family of operculate terrestrial molluscs, the Cyclophoridae. Chondrocyclus snails are small gastropods found in forest and moist thicket throughout South Africa. This is the first detailed systematic treatment of a group of Cyclophoridae in mainland Africa and the first to provide molecular data. This study complements regional studies on the systematics of the family in Asia and provides comparative data for studies of higher level relationships within the Cyclophoridae. Phylogenetic reconstruction by BI and ML methods of combined and single gene datasets of 16S and CO 1 all showed Chondrocyclus to be monophyletic and recovered five well-supported clades that corresponded to groups of populations identifiable on the basis of combinations of morphological characters. Species were diagnosed morphologically and were shown to be genetically distinct lineages. Informative morphological features include shell dimensions, protoconch, periostracum, operculum, radula and penis. Two species in Afromontane regions of Zimbabwe and Malawi respectively are excluded from Chondrocyclus based on morphology and tentatively placed in Cyathopoma. Diversity recognised within the genus more than doubled, from a previous seven South African species to seventeen. Re-descriptions of established species and descriptions of new species are provided, together with photographs of morphological characteristics. New taxon names and nomenclatural acts within it are disclaimed and are therefore not available in the sense of the International Code of Zoological Nomenclature until validly published elsewhere. Several cryptic species within previously widespread “species” and unrecorded narrowly endemic species were documented. The clade consisting of populations of “Chondrocyclus isipingoensis”, now considered to be a species complex, was sister to a group containing the other four clades. The “Isipingoensis” clade occurs widely in Afromontane regions, along the Great Escarpment, and on the south-east coast. The other four clades occur from Zululand to the Cape Peninsula with a pattern of east-west lineage turnover. The biogeography of Chondrocyclus is interpreted by comparison with concordant patterns in other terrestrial molluscs and unrelated taxa with poor dispersal ability. This study complements other research on composition, spatial distribution and phylogenetic diversity of low-vagility invertebrates and expands the data available for biodiversity conservation in South Africa.
- Full Text:
Talent management: a case study of Namibia’s Directorate of Civil Aviation (DCA) in securing talent for aviation safety, 2008 to 2014
- Authors: Simataa, George
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7131 , vital:21220
- Description: This study is about talent management, focusing on a case study of the initiatives undertaken by the Directorate of Civil Aviation (DCA) of Namibia over the period 2008 to 2014 in securing talent for aviation safety. The International Civil Aviation Organisation (ICAO) regularly assesses the extent to which member states comply with their safety oversight responsibilities. According to a 1996 report by the ICAO, under the auspices of its Universal Safety Oversight and Security Audit Programme (USOSAP), Namibia’s safety oversight was found to be weak, as indicative of the State’s inability to guarantee the safety of aircraft operations within the national airspace (ICAO, 1996). One of the significant audit findings was the critical shortage of qualified professionals at the Directorate Civil Aviation (DCA) to effectively perform the State’s regulatory and oversight function as contained in the Chicago Convention of 1944. The shortage of qualified professionals resulted in Namibia being unable to respond to its obligations and responsibilities under the Chicago Convention and Namibia’s subsequent blacklisting by the ICAO Audit Result Review Board (ARRB). Consequently, a corrective action plan was undertaken. This study examines one aspect of this plan, namely the initiatives that were undertaken to secure the talent required for aviation safety posts. The aim of the research is, from the perspective of talent management, to analyse the corrective action plan of the Directorate of Civil Aviation (DCA), as a process of securing talent for strategic positions in aviation safety in Namibia. This initiative was analysed from the perspective of the fourth stream of talent management, which emphasises securing talent for strategic positions (Collings and Mellahi, 2009; Huselid & Becker, 2011). Taking into account the fact that Namibia was a racially and culturally divided society until about 25 years ago, the study also deals with issues of diversity management as they impacted upon the talent management of the civil aviation industry nationally. Furthermore, the study is located against the background of the Bantu Education System that was provided by the apartheid South African government to Namibians before independence in 1990. The research design of this study involved conducting a case study that followed a deductive approach. Data were collected using multiple methods and sources such as documentation, interviews and archival records. Content analysis was used in the analysis of collected data. The findings of the study showed the talent management strategies that were adopted in managing strategic positions, the challenges encountered and the impact of the programme. The findings were initially discussed from the perspective of stream four of talent management, with its focus on strategic positions in organisations. Some of the findings of the study were in line with this approach to talent management, but certain challenges that were encountered in carrying out the talent management programme could not be addressed from this perspective, thereby exposing the limits of this approach to talent management in an emerging economy like Namibia. Consequently, a proposed model of sustainable talent management for the DCA was developed. From the perspective of this model of sustainable talent management, recommendations were made for practice and further research.
- Full Text:
- Authors: Simataa, George
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7131 , vital:21220
- Description: This study is about talent management, focusing on a case study of the initiatives undertaken by the Directorate of Civil Aviation (DCA) of Namibia over the period 2008 to 2014 in securing talent for aviation safety. The International Civil Aviation Organisation (ICAO) regularly assesses the extent to which member states comply with their safety oversight responsibilities. According to a 1996 report by the ICAO, under the auspices of its Universal Safety Oversight and Security Audit Programme (USOSAP), Namibia’s safety oversight was found to be weak, as indicative of the State’s inability to guarantee the safety of aircraft operations within the national airspace (ICAO, 1996). One of the significant audit findings was the critical shortage of qualified professionals at the Directorate Civil Aviation (DCA) to effectively perform the State’s regulatory and oversight function as contained in the Chicago Convention of 1944. The shortage of qualified professionals resulted in Namibia being unable to respond to its obligations and responsibilities under the Chicago Convention and Namibia’s subsequent blacklisting by the ICAO Audit Result Review Board (ARRB). Consequently, a corrective action plan was undertaken. This study examines one aspect of this plan, namely the initiatives that were undertaken to secure the talent required for aviation safety posts. The aim of the research is, from the perspective of talent management, to analyse the corrective action plan of the Directorate of Civil Aviation (DCA), as a process of securing talent for strategic positions in aviation safety in Namibia. This initiative was analysed from the perspective of the fourth stream of talent management, which emphasises securing talent for strategic positions (Collings and Mellahi, 2009; Huselid & Becker, 2011). Taking into account the fact that Namibia was a racially and culturally divided society until about 25 years ago, the study also deals with issues of diversity management as they impacted upon the talent management of the civil aviation industry nationally. Furthermore, the study is located against the background of the Bantu Education System that was provided by the apartheid South African government to Namibians before independence in 1990. The research design of this study involved conducting a case study that followed a deductive approach. Data were collected using multiple methods and sources such as documentation, interviews and archival records. Content analysis was used in the analysis of collected data. The findings of the study showed the talent management strategies that were adopted in managing strategic positions, the challenges encountered and the impact of the programme. The findings were initially discussed from the perspective of stream four of talent management, with its focus on strategic positions in organisations. Some of the findings of the study were in line with this approach to talent management, but certain challenges that were encountered in carrying out the talent management programme could not be addressed from this perspective, thereby exposing the limits of this approach to talent management in an emerging economy like Namibia. Consequently, a proposed model of sustainable talent management for the DCA was developed. From the perspective of this model of sustainable talent management, recommendations were made for practice and further research.
- Full Text:
The contribution of non-timber forest products to rural livelihoods and their price determination in different agro-ecological zones of South Africa
- Authors: Mugido, Worship
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5176 , vital:20783
- Description: A large number of studies have been conducted on the contribution of different types of non-timber forest products (NTFPs) to rural livelihoods. However, not many of these have considered the context in which these contributions are made, especially agro-ecological potential. Similarly, there are few studies that focus on the price setting of NTFPs in different settings as most are based on a single or relatively few sites. Thus, there is no indication of the prevalence of the different factors within a uniform macro context, nor how they might vary between different types of NTFPs. Therefore, the aim of this thesis was to establish the contribution of NTFPs to rural livelihoods and their price determination in areas of varying agro-ecological potential of South Africa. The study used data from 1 200 randomly selected households across four agro-ecological zones of South Africa to quantify the contribution of NTFP income to total household income, the proportion of households selling at least a single NTFP and the nature and extent of use of NTFPs as safety nets in areas of varying agro-ecological potential. In addition, 300 sellers of NTFPs in 15 towns across South Africa were interviewed to assess the factors they take into account when setting prices. The findings of this study support the argument that the level of dependence on NFTPs varies with agro-ecological conditions. This was supported by the significant difference between the NTFP incomes of the following pairs of agro-ecological classes: very low and low, medium and high. About 6.4 % households reported selling one or more NTFPs for various reasons, with many (39 %) citing the need to earn cash income and limited employment opportunities (16.9 %). Income from trading NTFPs is undoubtedly an important source of cash income for many rural households. Thus, 300 sellers, selling either at home or in town, were interviewed and the majority (79.3 %) of the sellers reported that selling NTFPs was their main source of cash household income, with only 8 % and 5.7 % receiving their main cash household income from state child grants and state pension grants, respectively. The pricing factors considered by sellers when setting the prices of NTFPs tended to vary with the type of NTFP being sold, type of market (home markets or urban markets) and the method used by the seller to procure the stock. However, overall, transport costs (29 %), stock price (18.4 %), profit margin (12.7 %), time taken to collect or produce the product (7.3 %) and the market price (6.4 %) were the widely used factors to determine prices for NTFPs. The reported various pricing factors showed that there was no formal or certain price mechanism that was used by the sellers of NTFPs to establish the market prices of NTFPs. The study found that about 79 % of the total households interviewed experienced at least one shock of some magnitude in the previous 12 months. The most common shocks were illness (43 %), death (42 %), crop failure (29 %) and hunger (22 %). The households employed various coping strategies (21) in response to different types of shocks, with the three widely used strategies being assistance from friends and relatives (60.1 %), using cash savings (37.9%) and using NTFPs (35.6 %). Shocks, hunger or food shortage and crop failure were significantly and positively related to the usage of NTFPs as safety nets. Therefore, households who experienced hunger or food shortage and crop failure were likely to use NTFPs to cope with these shocks. The study concluded that NTFPs are an integral part of the rural livelihoods, especially for the households living close to the survival line.
- Full Text:
- Authors: Mugido, Worship
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5176 , vital:20783
- Description: A large number of studies have been conducted on the contribution of different types of non-timber forest products (NTFPs) to rural livelihoods. However, not many of these have considered the context in which these contributions are made, especially agro-ecological potential. Similarly, there are few studies that focus on the price setting of NTFPs in different settings as most are based on a single or relatively few sites. Thus, there is no indication of the prevalence of the different factors within a uniform macro context, nor how they might vary between different types of NTFPs. Therefore, the aim of this thesis was to establish the contribution of NTFPs to rural livelihoods and their price determination in areas of varying agro-ecological potential of South Africa. The study used data from 1 200 randomly selected households across four agro-ecological zones of South Africa to quantify the contribution of NTFP income to total household income, the proportion of households selling at least a single NTFP and the nature and extent of use of NTFPs as safety nets in areas of varying agro-ecological potential. In addition, 300 sellers of NTFPs in 15 towns across South Africa were interviewed to assess the factors they take into account when setting prices. The findings of this study support the argument that the level of dependence on NFTPs varies with agro-ecological conditions. This was supported by the significant difference between the NTFP incomes of the following pairs of agro-ecological classes: very low and low, medium and high. About 6.4 % households reported selling one or more NTFPs for various reasons, with many (39 %) citing the need to earn cash income and limited employment opportunities (16.9 %). Income from trading NTFPs is undoubtedly an important source of cash income for many rural households. Thus, 300 sellers, selling either at home or in town, were interviewed and the majority (79.3 %) of the sellers reported that selling NTFPs was their main source of cash household income, with only 8 % and 5.7 % receiving their main cash household income from state child grants and state pension grants, respectively. The pricing factors considered by sellers when setting the prices of NTFPs tended to vary with the type of NTFP being sold, type of market (home markets or urban markets) and the method used by the seller to procure the stock. However, overall, transport costs (29 %), stock price (18.4 %), profit margin (12.7 %), time taken to collect or produce the product (7.3 %) and the market price (6.4 %) were the widely used factors to determine prices for NTFPs. The reported various pricing factors showed that there was no formal or certain price mechanism that was used by the sellers of NTFPs to establish the market prices of NTFPs. The study found that about 79 % of the total households interviewed experienced at least one shock of some magnitude in the previous 12 months. The most common shocks were illness (43 %), death (42 %), crop failure (29 %) and hunger (22 %). The households employed various coping strategies (21) in response to different types of shocks, with the three widely used strategies being assistance from friends and relatives (60.1 %), using cash savings (37.9%) and using NTFPs (35.6 %). Shocks, hunger or food shortage and crop failure were significantly and positively related to the usage of NTFPs as safety nets. Therefore, households who experienced hunger or food shortage and crop failure were likely to use NTFPs to cope with these shocks. The study concluded that NTFPs are an integral part of the rural livelihoods, especially for the households living close to the survival line.
- Full Text:
The effects of graphene and other nanomaterials on the electrocatalytic behaviour of phthalocyanines
- Authors: Shumba, Munyaradzi
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/37952 , vital:24712
- Description: Carbon based nanomaterials, gold nanorods and metallophthalocyanine nanoconjugates have been developed for electrocatalysis. Carbon based nanomaterials used are multiwalled carbon nanotubes, pristine graphene oxide nanosheets, nitrogen, boron, sulphur, phosphorus doped graphene oxide nanosheets. Cobalt phthalocyanine (CoPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPhPc), cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) and cobalt tetra carboxyphenoxy phthalocyanine (CoTCPhPc) are the phthalocyanines employed in this work. Metallophthalocyanines were employed either in their bulk form or in their nanosized form. Electrode modification by these nanomaterials was either done sequentially, premixed or linked nanoconjugates. In all sequential modification, phthalocyanines were employed on top of other nanomaterials. Sequentially modified electrodes gave higher detection currents than both premixed and covalently bonded nanoconjugates. The nanomaterials reported here were characterised by transmission electron microscopy, Raman spectroscopy, time of flight secondary ion mass spectrometry, and X-ray diffraction among other techniques. The modified electrodes were further characterised by scanning electron microscopy, scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry, while square wave, linear scan and cyclic voltammetry, rotating disc electrode and chronoamperometry have been used to evaluate the electrocatalytic behaviour of the previously mentioned towards either oxidation or reduction of L-cysteine and/or hydrogen peroxide respectively. Generally, the nanoconjugates resulted in superior catalytic performance compared to the performance of individual nanomaterials. Zinc octacarboxy phthalocyanine (ZnOCPc) conjugated to either GONS or rGONS were employed to compare electrocatalytic detection of hydrogen peroxide to its luminescence sensing.
- Full Text:
The effects of graphene and other nanomaterials on the electrocatalytic behaviour of phthalocyanines
- Authors: Shumba, Munyaradzi
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/37952 , vital:24712
- Description: Carbon based nanomaterials, gold nanorods and metallophthalocyanine nanoconjugates have been developed for electrocatalysis. Carbon based nanomaterials used are multiwalled carbon nanotubes, pristine graphene oxide nanosheets, nitrogen, boron, sulphur, phosphorus doped graphene oxide nanosheets. Cobalt phthalocyanine (CoPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPhPc), cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) and cobalt tetra carboxyphenoxy phthalocyanine (CoTCPhPc) are the phthalocyanines employed in this work. Metallophthalocyanines were employed either in their bulk form or in their nanosized form. Electrode modification by these nanomaterials was either done sequentially, premixed or linked nanoconjugates. In all sequential modification, phthalocyanines were employed on top of other nanomaterials. Sequentially modified electrodes gave higher detection currents than both premixed and covalently bonded nanoconjugates. The nanomaterials reported here were characterised by transmission electron microscopy, Raman spectroscopy, time of flight secondary ion mass spectrometry, and X-ray diffraction among other techniques. The modified electrodes were further characterised by scanning electron microscopy, scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry, while square wave, linear scan and cyclic voltammetry, rotating disc electrode and chronoamperometry have been used to evaluate the electrocatalytic behaviour of the previously mentioned towards either oxidation or reduction of L-cysteine and/or hydrogen peroxide respectively. Generally, the nanoconjugates resulted in superior catalytic performance compared to the performance of individual nanomaterials. Zinc octacarboxy phthalocyanine (ZnOCPc) conjugated to either GONS or rGONS were employed to compare electrocatalytic detection of hydrogen peroxide to its luminescence sensing.
- Full Text:
The emergence and expression of teachers’ identities in teaching foundation phase mathematics
- Authors: Westaway, Lise
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7000 , vital:21208
- Description: The assertion that learner performance in South African schools is in crisis may be cliched but it is certainly true. The majority of learners in the schooling system are not achieving the required outcomes, particularly in language and mathematics. I use the underperformance of learners in mathematics as the impetus for my research which seeks to understand how teachers’ identities emerge and are expressed in teaching Foundation Phase mathematics. The research contributes to an emerging scholarship that strives to explain underperformance and quality in mathematics classrooms beyond structuralist theorising. Recently research, particularly in South Africa, has begun to look more closely at who the teacher is and how the teacher is key in understanding what happens in the mathematics classroom. This emerging scholarship focuses on teacher identities. Research that foregrounds teacher identities within the field of mathematics education tends to be situated within a social constructionist orientation, which assumes that our knowledge of self and the world comes from our interactions with people and not some ‘objective’ reality (Berger & Luckman, 1966). Such a perspective appears to conflate questions of how we know something with what is. In other words, it elides structure and agency, thereby making research that seeks to examine the interplay between the two in the formation and expression of teachers’ identities, practically impossible. It is for this reason, as well as the need to move beyond the hermeneutic, that my research draws on Margaret Archer’s (1995, 1996, 2000) social realist framework. Social realism posits a relativist epistemology but a realist ontology. It is underpinned by the notion of a stratified reality with structural mechanisms giving rise to events in the world whether we experience them or not. It is only through the (inter)actions of persons that such mechanisms have the tendential power to constrain or enable the projects of persons. As such, my research seeks to identify the structural and agential mechanisms that give rise to teachers’ identities and how these identities are expressed in teaching Foundation Phase mathematics. In my research, teacher identity refers to the manner in which teachers express their social roles as teachers. In the research I use a case study methodology. I provide rich data on four isiXhosa teachers teaching in low socio-economic status schools. This data is gleaned through interviews and classroom based observations which were recorded as field notes and video transcripts. Analysis of the data occurs through the thought processes of abduction and retroduction (Danermark, Ekstrom, Jakobsen, & Karlsson, 2002). These thought process enable me to (re)describe and (re)contextualise the object of study. Through the process of asking transfactual questions I identify the structural, cultural and agential mechanisms giving rise to teachers’ identities and their expression in teaching foundation phase mathematics. There are three significant findings in my research. Firstly, research that attempts to understand the emergence and expression of teacher identities should consider their broad contextual realities. The historical, economic, social and political contexts in which the teachers are born and live, influences their sense of self, personal identities and social identities (teacher identities) and as such, influences their decision to become teachers and how they express their roles as teachers of Foundation Phase mathematics. Secondly, my research suggests that teachers’ mode of reflexivity is key to understanding the decisions that they make in the classroom and how they deal with the structures that condition the manner in which they express their roles as teachers. Thirdly, collective agency is necessary to bring about change in the way in which teachers express their roles in teaching Foundation Phase mathematics. My research produces new knowledge by examining the interplay of structure, culture and agency in the constitution of foundation phase teachers’ identities and their expression in teaching foundation phase mathematics. I use a social realist orientation to examine this interplay and provide an understanding of the mechanisms giving rise to the phenomenon under consideration. In this way I contribute to the extensive research on learner underperformance by focusing more explicitly on who the teacher is in the classroom.
- Full Text:
- Authors: Westaway, Lise
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7000 , vital:21208
- Description: The assertion that learner performance in South African schools is in crisis may be cliched but it is certainly true. The majority of learners in the schooling system are not achieving the required outcomes, particularly in language and mathematics. I use the underperformance of learners in mathematics as the impetus for my research which seeks to understand how teachers’ identities emerge and are expressed in teaching Foundation Phase mathematics. The research contributes to an emerging scholarship that strives to explain underperformance and quality in mathematics classrooms beyond structuralist theorising. Recently research, particularly in South Africa, has begun to look more closely at who the teacher is and how the teacher is key in understanding what happens in the mathematics classroom. This emerging scholarship focuses on teacher identities. Research that foregrounds teacher identities within the field of mathematics education tends to be situated within a social constructionist orientation, which assumes that our knowledge of self and the world comes from our interactions with people and not some ‘objective’ reality (Berger & Luckman, 1966). Such a perspective appears to conflate questions of how we know something with what is. In other words, it elides structure and agency, thereby making research that seeks to examine the interplay between the two in the formation and expression of teachers’ identities, practically impossible. It is for this reason, as well as the need to move beyond the hermeneutic, that my research draws on Margaret Archer’s (1995, 1996, 2000) social realist framework. Social realism posits a relativist epistemology but a realist ontology. It is underpinned by the notion of a stratified reality with structural mechanisms giving rise to events in the world whether we experience them or not. It is only through the (inter)actions of persons that such mechanisms have the tendential power to constrain or enable the projects of persons. As such, my research seeks to identify the structural and agential mechanisms that give rise to teachers’ identities and how these identities are expressed in teaching Foundation Phase mathematics. In my research, teacher identity refers to the manner in which teachers express their social roles as teachers. In the research I use a case study methodology. I provide rich data on four isiXhosa teachers teaching in low socio-economic status schools. This data is gleaned through interviews and classroom based observations which were recorded as field notes and video transcripts. Analysis of the data occurs through the thought processes of abduction and retroduction (Danermark, Ekstrom, Jakobsen, & Karlsson, 2002). These thought process enable me to (re)describe and (re)contextualise the object of study. Through the process of asking transfactual questions I identify the structural, cultural and agential mechanisms giving rise to teachers’ identities and their expression in teaching foundation phase mathematics. There are three significant findings in my research. Firstly, research that attempts to understand the emergence and expression of teacher identities should consider their broad contextual realities. The historical, economic, social and political contexts in which the teachers are born and live, influences their sense of self, personal identities and social identities (teacher identities) and as such, influences their decision to become teachers and how they express their roles as teachers of Foundation Phase mathematics. Secondly, my research suggests that teachers’ mode of reflexivity is key to understanding the decisions that they make in the classroom and how they deal with the structures that condition the manner in which they express their roles as teachers. Thirdly, collective agency is necessary to bring about change in the way in which teachers express their roles in teaching Foundation Phase mathematics. My research produces new knowledge by examining the interplay of structure, culture and agency in the constitution of foundation phase teachers’ identities and their expression in teaching foundation phase mathematics. I use a social realist orientation to examine this interplay and provide an understanding of the mechanisms giving rise to the phenomenon under consideration. In this way I contribute to the extensive research on learner underperformance by focusing more explicitly on who the teacher is in the classroom.
- Full Text:
The epidemiology of African horse sickness in the Eastern Cape, South Africa
- Authors: Riddin, Megan Amy
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64460 , vital:28546
- Description: Expected release date-May 2019
- Full Text:
- Authors: Riddin, Megan Amy
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64460 , vital:28546
- Description: Expected release date-May 2019
- Full Text:
The isolation and genetic characterisation of a novel alphabaculovirus for the microbial control of Cryptophlebia peltastica and closely related tortricid pests
- Authors: Marsberg, Tamryn
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59292 , vital:27543
- Description: Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) is an economically damaging pest of litchis and macadamias in South Africa. Cryptophlebia peltastica causes both pre- and post-harvest damage to litchis, reducing overall yields and thus classifying the pest as a phytosanitary risk. Various control methods have been implemented against C. peltastica in an integrated pest management programme. These control methods include chemical control, cultural control and biological control. However, these methods have not yet provided satisfactory control as of yet. As a result, an alternative control option needs to be identified and implemented into the IPM programme. An alternative method of control that has proved successful in other agricultural sectors and not yet implemented in the control of C. peltastica is that of microbial control, specifically the use of baculovirus biopesticides. This study aimed to isolate and characterise a novel baculovirus from a laboratory culture of C. peltastica that could be used as a commercially available baculovirus biopesticide. In order to isolate a baculovirus a laboratory culture of C. peltastica was successfully established at Rhodes University, Grahamstown, South Africa. This is the first time a laboratory culture of C. peltastica has been established. This allowed for various biological aspects of the pest to be determined, which included: length of the life cycle, fecundity and time to oviposition, egg and larval development and percentage hatch. The results obtained from these studies found that the biology of C. peltastica was similar to that of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Once the laboratory culture had reached high densities, larvae showing symptoms of baculovirus infection were observed. Symptomatic larvae were collected and examined for the presence of a baculovirus. An alphabaculovirus (NPV) was successfully isolated and morphologically identified using purified OBs that were sectioned and observed by transmission electron microscopy. This was then confirmed by amplifying the polyhedrin gene region using degenerate primers. A BLAST analysis found a 93% similarity to a partial polyhedrin gene sequence to be that of Epinotia granitalis (Butler) (Lepidoptera: Tortricidae). The alphabaculovirus was then genetically characterised by generating restriction profiles and sequencing the whole genome. Due to the novelty of the virus, no comparison could be made. The biological activity of the alphabaculovirus was then tested against C. peltastica and two closely related Tortricidae pests: T. leucotreta and Cydiapomonella (Linnaeous) (Lepidoptera: Tortricidae). The alphabaculovirus was highly virulent against all three species. The lethal concentrations (LC50 and LC90) for the virus against C. peltastica was 8.19 x 103 and 3.33 x 105 OBs/ml. The LC50 and LC90 for T. leucotreta was 2.29 x 103 and 9.97 x 104 OBs/ml, respectively and C. pomonella had a LC50 of 1.43 x 103 OBs/ml and LC90 1.26 x 104 OBs/ml. The virus was particularly virulent against T. leucotreta and C. pomonella as compared to C. peltastica. The biological activity of the alphabaculovirus was also tested against CpGV resistant European C. pomonella. From the results it was observed that the virus had the ability to overcome the resistance in C. pomonella and could potentially be used in the resistance management of C. pomonella. With the successful biological activity results obtained from this study, preliminary investigation were made into the mass production of the alphabaculovirus using both the in vivo and in vitro production methods. For in vivo production both the homologous host (C. peltastica) and a heterologous host (T leucotreta) were investigated. Preliminary studies focused on determining the biological activity in fifth instars of both hosts. Fifth instar LC50 and LC90 values for C. peltastica were 3.43 x 103 and 1.11 x 107 OBs/ml and for T. leucotreta the LC50 and LC90 values were 2.53 x 103 and 8.82 x 106 OBs/ml, respectively. The average yield of virus produced in each species was also determined. Cryptophlebia peltastica had the highest viral yield of 5.37 x 1010 OBs/larva and 2.93 x 1010 OBs/larva for T. leucotreta. The results obtained, from the preliminary investigation concluded that the virus could be produced in vivo in both C. peltastica and T. leucotreta, however further research is required into the mass production in both hosts. The in vitro production of the virus was also considered and the susceptibility of the virus was tested against the C. pomonella cell line, Cp14R. After infection of the Cp14R cells with budded virus collected from fifth instar C. peltastica larvae, OBs could be observed after three days. Thus, the alphabaculovirus is susceptible to the Cp14R cell line, thus has the potential to be produced in vitro and further characterised. This study is the first to report of the identification and characterisation of a novel alphabaculovirus isolated from a laboratory reared culture of C. peltastica and the potential for it to be commercially developed into a bipoesticide and used against Tortricidae pests.
- Full Text:
- Authors: Marsberg, Tamryn
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59292 , vital:27543
- Description: Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) is an economically damaging pest of litchis and macadamias in South Africa. Cryptophlebia peltastica causes both pre- and post-harvest damage to litchis, reducing overall yields and thus classifying the pest as a phytosanitary risk. Various control methods have been implemented against C. peltastica in an integrated pest management programme. These control methods include chemical control, cultural control and biological control. However, these methods have not yet provided satisfactory control as of yet. As a result, an alternative control option needs to be identified and implemented into the IPM programme. An alternative method of control that has proved successful in other agricultural sectors and not yet implemented in the control of C. peltastica is that of microbial control, specifically the use of baculovirus biopesticides. This study aimed to isolate and characterise a novel baculovirus from a laboratory culture of C. peltastica that could be used as a commercially available baculovirus biopesticide. In order to isolate a baculovirus a laboratory culture of C. peltastica was successfully established at Rhodes University, Grahamstown, South Africa. This is the first time a laboratory culture of C. peltastica has been established. This allowed for various biological aspects of the pest to be determined, which included: length of the life cycle, fecundity and time to oviposition, egg and larval development and percentage hatch. The results obtained from these studies found that the biology of C. peltastica was similar to that of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Once the laboratory culture had reached high densities, larvae showing symptoms of baculovirus infection were observed. Symptomatic larvae were collected and examined for the presence of a baculovirus. An alphabaculovirus (NPV) was successfully isolated and morphologically identified using purified OBs that were sectioned and observed by transmission electron microscopy. This was then confirmed by amplifying the polyhedrin gene region using degenerate primers. A BLAST analysis found a 93% similarity to a partial polyhedrin gene sequence to be that of Epinotia granitalis (Butler) (Lepidoptera: Tortricidae). The alphabaculovirus was then genetically characterised by generating restriction profiles and sequencing the whole genome. Due to the novelty of the virus, no comparison could be made. The biological activity of the alphabaculovirus was then tested against C. peltastica and two closely related Tortricidae pests: T. leucotreta and Cydiapomonella (Linnaeous) (Lepidoptera: Tortricidae). The alphabaculovirus was highly virulent against all three species. The lethal concentrations (LC50 and LC90) for the virus against C. peltastica was 8.19 x 103 and 3.33 x 105 OBs/ml. The LC50 and LC90 for T. leucotreta was 2.29 x 103 and 9.97 x 104 OBs/ml, respectively and C. pomonella had a LC50 of 1.43 x 103 OBs/ml and LC90 1.26 x 104 OBs/ml. The virus was particularly virulent against T. leucotreta and C. pomonella as compared to C. peltastica. The biological activity of the alphabaculovirus was also tested against CpGV resistant European C. pomonella. From the results it was observed that the virus had the ability to overcome the resistance in C. pomonella and could potentially be used in the resistance management of C. pomonella. With the successful biological activity results obtained from this study, preliminary investigation were made into the mass production of the alphabaculovirus using both the in vivo and in vitro production methods. For in vivo production both the homologous host (C. peltastica) and a heterologous host (T leucotreta) were investigated. Preliminary studies focused on determining the biological activity in fifth instars of both hosts. Fifth instar LC50 and LC90 values for C. peltastica were 3.43 x 103 and 1.11 x 107 OBs/ml and for T. leucotreta the LC50 and LC90 values were 2.53 x 103 and 8.82 x 106 OBs/ml, respectively. The average yield of virus produced in each species was also determined. Cryptophlebia peltastica had the highest viral yield of 5.37 x 1010 OBs/larva and 2.93 x 1010 OBs/larva for T. leucotreta. The results obtained, from the preliminary investigation concluded that the virus could be produced in vivo in both C. peltastica and T. leucotreta, however further research is required into the mass production in both hosts. The in vitro production of the virus was also considered and the susceptibility of the virus was tested against the C. pomonella cell line, Cp14R. After infection of the Cp14R cells with budded virus collected from fifth instar C. peltastica larvae, OBs could be observed after three days. Thus, the alphabaculovirus is susceptible to the Cp14R cell line, thus has the potential to be produced in vitro and further characterised. This study is the first to report of the identification and characterisation of a novel alphabaculovirus isolated from a laboratory reared culture of C. peltastica and the potential for it to be commercially developed into a bipoesticide and used against Tortricidae pests.
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The life and literary works of Peter Tshobiso Mtuze: a critical analysis
- Authors: Mafrika, Andile Ernest
- Date: 2017
- Subjects: Mtuze, P T -- Criticism and interpretation , Mtuze, P T -- UDingezweni , Mtuze, P T -- Alitshoni lingaphumi , Mtuze, P T -- Amathol’ eendaba. , Authors, Xhosa , Xhosa literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4400 , vital:20658
- Description: This thesis is an exploration of the concept of Mphahlele’s African Humanism, against the backdrop of the life and work of Peter Tshobiso Mtuze, well-known author of isiXhosa books, critic, academic and spiritual leader. Mtuze’s commitment to the collective rather than the individual is clearly illustrated in the thesis, suggesting that his early life of struggle, his belated development as an acclaimed academic, as well as his spiritual growth are all intertwined and underpinned by African Humanism and an Afrocentric ethos.The thesis consists of six chapters with each chapter focusing on a particular aspect of the research topic. Chapter One deals with the introduction to the research topic. Part of the introductory material consists of conventional preliminaries such as a research statement, aim of study, methodology, main assumptions of the study and the significance and benefit of the study. Chapter Two is the theoretical foundation of the thesis. It covers the origin of African Humanism as consciousness and as a system of society, oral and written literature in Africa and the early Xhosa literary humanism. Chapter Three is an overview of the biographical background of Peter Tshobiso Mtuze, his Pass Law battles in different towns of South Africa, how he joined the African National Congress (ANC) and his working life and writing life. Chapter Four analyses two major novels, UDingezweni and Alitshoni lingaphumi, and a short story book, Amathol’ eendaba. The analysis aims at revealing African consciousness and African way of life with specific reference to Xhosa people. Chapter Five deals with Xhosa spirituality, its aspects and symbols, Mtuze’s Spirituality and Anglicanism and his writings. Chapter Six is a general conclusion that highlights the main aspects of the thesis, the African personality and the prospects of African humanism in today’s world.
- Full Text:
- Authors: Mafrika, Andile Ernest
- Date: 2017
- Subjects: Mtuze, P T -- Criticism and interpretation , Mtuze, P T -- UDingezweni , Mtuze, P T -- Alitshoni lingaphumi , Mtuze, P T -- Amathol’ eendaba. , Authors, Xhosa , Xhosa literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4400 , vital:20658
- Description: This thesis is an exploration of the concept of Mphahlele’s African Humanism, against the backdrop of the life and work of Peter Tshobiso Mtuze, well-known author of isiXhosa books, critic, academic and spiritual leader. Mtuze’s commitment to the collective rather than the individual is clearly illustrated in the thesis, suggesting that his early life of struggle, his belated development as an acclaimed academic, as well as his spiritual growth are all intertwined and underpinned by African Humanism and an Afrocentric ethos.The thesis consists of six chapters with each chapter focusing on a particular aspect of the research topic. Chapter One deals with the introduction to the research topic. Part of the introductory material consists of conventional preliminaries such as a research statement, aim of study, methodology, main assumptions of the study and the significance and benefit of the study. Chapter Two is the theoretical foundation of the thesis. It covers the origin of African Humanism as consciousness and as a system of society, oral and written literature in Africa and the early Xhosa literary humanism. Chapter Three is an overview of the biographical background of Peter Tshobiso Mtuze, his Pass Law battles in different towns of South Africa, how he joined the African National Congress (ANC) and his working life and writing life. Chapter Four analyses two major novels, UDingezweni and Alitshoni lingaphumi, and a short story book, Amathol’ eendaba. The analysis aims at revealing African consciousness and African way of life with specific reference to Xhosa people. Chapter Five deals with Xhosa spirituality, its aspects and symbols, Mtuze’s Spirituality and Anglicanism and his writings. Chapter Six is a general conclusion that highlights the main aspects of the thesis, the African personality and the prospects of African humanism in today’s world.
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The making of ‘loyals’ and ‘rebels’: the 1880 Transkei Rebellion and the Subversion of the chieftaincies of East Griqualand, 1874-1914
- Authors: Snell, Milner Charles
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41860 , vital:25142
- Description: In the mid-1870s, influenced by the mineral revolution in southern Africa, the Cape responsible government began to extend colonial rule over the chiefdoms that inhabited the Mthatha- Mzimkhulu region. Although white officials initially negotiated with the leadership of these chiefdoms to accept colonial rule and depended heavily on them to implement new laws, ultimately the Cape government aimed to side-line indigenous political systems and replace them with magistrates and headmen. Colonial officials mistakenly equated indigenous political structures with dictatorial chiefs whose followers were subject to their personal ambitions. In fact chiefs were part of a collective leadership and were very aware and influenced by the needs of their adherents. This work is concerned with how the chieftaincies, or indigenous political systems, of the Mthatha-Mzimkhulu region responded, survived and adapted in the face of colonialism. The chieftaincies were remarkably resilient despite the political and economic changes brought on by colonialism and capitalism and were able to retain some degree of authority amongst their followers and at times obtain recognition from the colonial state. Interactions between the chieftaincies and the colonial state were complex, fluid and ever evolving. Some leaders of chiefdoms co-operated with colonial authorities, either over particular issues at certain times or more generally over longer periods, and were considered by colonial officials to be ‘loyal’. Yet, at other times they resisted the demands and changes being brought on by colonialism and were labelled as ‘rebels’. Questions of how the chieftaincies responded to colonial rule were most critical during the Transkei Rebellion of 1880, which is a central focus of this work. Some chieftaincies co-operated with and served with the colonial military forces in order to spare themselves from the economic and social disruption brought on by war and the confiscation of land by the victors. Other chieftaincies took up arms against the colonial state in an attempt to stop the increasingly unacceptable demands being made of them and to resist the negative changes that colonialism was bringing. Despite their ability to adapt, by the early years of the twentieth century hereditary leaders found themselves increasingly caught between the expectations of their followers and demands made by the colonial administration. Faced with increasing popular criticism, many leaders adapted ambiguous and shifting stances on issues concerning their followers.
- Full Text:
- Authors: Snell, Milner Charles
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41860 , vital:25142
- Description: In the mid-1870s, influenced by the mineral revolution in southern Africa, the Cape responsible government began to extend colonial rule over the chiefdoms that inhabited the Mthatha- Mzimkhulu region. Although white officials initially negotiated with the leadership of these chiefdoms to accept colonial rule and depended heavily on them to implement new laws, ultimately the Cape government aimed to side-line indigenous political systems and replace them with magistrates and headmen. Colonial officials mistakenly equated indigenous political structures with dictatorial chiefs whose followers were subject to their personal ambitions. In fact chiefs were part of a collective leadership and were very aware and influenced by the needs of their adherents. This work is concerned with how the chieftaincies, or indigenous political systems, of the Mthatha-Mzimkhulu region responded, survived and adapted in the face of colonialism. The chieftaincies were remarkably resilient despite the political and economic changes brought on by colonialism and capitalism and were able to retain some degree of authority amongst their followers and at times obtain recognition from the colonial state. Interactions between the chieftaincies and the colonial state were complex, fluid and ever evolving. Some leaders of chiefdoms co-operated with colonial authorities, either over particular issues at certain times or more generally over longer periods, and were considered by colonial officials to be ‘loyal’. Yet, at other times they resisted the demands and changes being brought on by colonialism and were labelled as ‘rebels’. Questions of how the chieftaincies responded to colonial rule were most critical during the Transkei Rebellion of 1880, which is a central focus of this work. Some chieftaincies co-operated with and served with the colonial military forces in order to spare themselves from the economic and social disruption brought on by war and the confiscation of land by the victors. Other chieftaincies took up arms against the colonial state in an attempt to stop the increasingly unacceptable demands being made of them and to resist the negative changes that colonialism was bringing. Despite their ability to adapt, by the early years of the twentieth century hereditary leaders found themselves increasingly caught between the expectations of their followers and demands made by the colonial administration. Faced with increasing popular criticism, many leaders adapted ambiguous and shifting stances on issues concerning their followers.
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The phenologies of macadamia (Proteaceae) and thrips (Insecta: Thysanoptera) communities in Mpumalanga Province, South Africa
- Authors: Hepburn, Colleen
- Date: 2017
- Subjects: Macadamia nut -- South Africa , Macadamia nut -- Ecology -- South Africa , Macadamia nut -- Diseases and pests -- South Africa , Thrips -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21183 , http://hdl.handle.net/10962/6817
- Description: Macadamia (Proteaceae) is indigenous to Australia; four of the nine species have been used in plant breeding for cultivation and the production of a rapidly growing product. First introduced to Hawaii in the 1880s, macadamias’ potential as a crop was only really considered in 1910. It is due to the early Hawaiian pioneers’ research and the development of Hawaiian cultivars upon which most of the current world’s production is based today. Prior to the 1980s, cultivation in Australia was based mainly on Hawaiian cultivars. Extensive research has been conducted on cultivar development, performance, best practice, production, crop protection and processing. South Africa has become one of the world’s leading producers and exporters of macadamias. The cultivation of macadamia in South Africa began 80 years ago, but the phenology of macadamia has not been rigorously studied under local conditions, and neither has the thrips communities in macadamia. Data collected during this study on the macadamia phenological stages can be used as a foundation on which seasonal data of all insect pests can be plotted, as a basis on which an extensive Integrated Pest Management (IPM) programme can be developed for the macadamia industry in South Africa. Extensive sampling of thrips communities present in macadamias was undertaken over two years, with more than 142,000 individuals collected. The most basic, common trait into which specimens could be sorted were colour groups. Specimens from each colour group were identified through slide-mounting individuals. Fifteen species of thrips were identified to species-level, excluding specimens from the Panchaetothripinae, Haplothrips and Scolothrips which occurred only periodically. The presence of larvae indicated that macadamia is a host plant for some species. Due to their size and morphology, identification i of the total collection could not be processed to species level using a dissection microscope, although Scirtothrips aurantii Faure were distinguishable from other species and their distribution over the seasons observed. Due to logistical constraints and events beyond the author’s control, the results are mainly qualitative. There seems to be phenological variation within and between cultivars. The date of anthesis and duration of immature nut-drop was estimated; some cultivars set out- of-season flowers and nuts; this “secondary crop” could have far-reaching effects on the implementation of an IPM programme. Comparisons of the phenological data of macadamia and thrips showed the highest abundances and diversity of thrips species occurred when flowers were present. An extensive study of abscised nuts showed no significant difference between most cultivars or at the sites where management practices were implemented and those sites where these practices were not. There was however a consistent difference between the two seasons. There was no difference in maturity of abscised nuts, regardless of whether thrips damage to the husk was present or not. Excessive Bathycoelia distincta (Hemiptera: Pentatomidae) damage was found on the kernels of the abscised nuts processed for maturity testing, which is more likely to have been the primary cause of abscission. The Author’s opinion is that thrips damage to the outer husk does not lead to abscission of maturing nuts. Ascertaining the cause of abscission at nut-set and immature nut-drop is more problematic as there are numerous other potential causes. Damage to new flush, especially the late summer flush essential for the build-up of carbohydrates and resources for the following yield, should be carefully monitored and controlled when necessary.
- Full Text:
- Authors: Hepburn, Colleen
- Date: 2017
- Subjects: Macadamia nut -- South Africa , Macadamia nut -- Ecology -- South Africa , Macadamia nut -- Diseases and pests -- South Africa , Thrips -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21183 , http://hdl.handle.net/10962/6817
- Description: Macadamia (Proteaceae) is indigenous to Australia; four of the nine species have been used in plant breeding for cultivation and the production of a rapidly growing product. First introduced to Hawaii in the 1880s, macadamias’ potential as a crop was only really considered in 1910. It is due to the early Hawaiian pioneers’ research and the development of Hawaiian cultivars upon which most of the current world’s production is based today. Prior to the 1980s, cultivation in Australia was based mainly on Hawaiian cultivars. Extensive research has been conducted on cultivar development, performance, best practice, production, crop protection and processing. South Africa has become one of the world’s leading producers and exporters of macadamias. The cultivation of macadamia in South Africa began 80 years ago, but the phenology of macadamia has not been rigorously studied under local conditions, and neither has the thrips communities in macadamia. Data collected during this study on the macadamia phenological stages can be used as a foundation on which seasonal data of all insect pests can be plotted, as a basis on which an extensive Integrated Pest Management (IPM) programme can be developed for the macadamia industry in South Africa. Extensive sampling of thrips communities present in macadamias was undertaken over two years, with more than 142,000 individuals collected. The most basic, common trait into which specimens could be sorted were colour groups. Specimens from each colour group were identified through slide-mounting individuals. Fifteen species of thrips were identified to species-level, excluding specimens from the Panchaetothripinae, Haplothrips and Scolothrips which occurred only periodically. The presence of larvae indicated that macadamia is a host plant for some species. Due to their size and morphology, identification i of the total collection could not be processed to species level using a dissection microscope, although Scirtothrips aurantii Faure were distinguishable from other species and their distribution over the seasons observed. Due to logistical constraints and events beyond the author’s control, the results are mainly qualitative. There seems to be phenological variation within and between cultivars. The date of anthesis and duration of immature nut-drop was estimated; some cultivars set out- of-season flowers and nuts; this “secondary crop” could have far-reaching effects on the implementation of an IPM programme. Comparisons of the phenological data of macadamia and thrips showed the highest abundances and diversity of thrips species occurred when flowers were present. An extensive study of abscised nuts showed no significant difference between most cultivars or at the sites where management practices were implemented and those sites where these practices were not. There was however a consistent difference between the two seasons. There was no difference in maturity of abscised nuts, regardless of whether thrips damage to the husk was present or not. Excessive Bathycoelia distincta (Hemiptera: Pentatomidae) damage was found on the kernels of the abscised nuts processed for maturity testing, which is more likely to have been the primary cause of abscission. The Author’s opinion is that thrips damage to the outer husk does not lead to abscission of maturing nuts. Ascertaining the cause of abscission at nut-set and immature nut-drop is more problematic as there are numerous other potential causes. Damage to new flush, especially the late summer flush essential for the build-up of carbohydrates and resources for the following yield, should be carefully monitored and controlled when necessary.
- Full Text:
Transcription factor binding specificity and occupancy : elucidation, modelling and evaluation
- Authors: Kibet, Caleb Kipkurui
- Date: 2017
- Subjects: Transcription factors , Transcription factors -- Data processing , Motif Assessment and Ranking Suite
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21185 , http://hdl.handle.net/10962/6838
- Description: The major contributions of this thesis are addressing the need for an objective quality evaluation of a transcription factor binding model, demonstrating the value of the tools developed to this end and elucidating how in vitro and in vivo information can be utilized to improve TF binding specificity models. Accurate elucidation of TF binding specificity remains an ongoing challenge in gene regulatory research. Several in vitro and in vivo experimental techniques have been developed followed by a proliferation of algorithms, and ultimately, the binding models. This increase led to a choice problem for the end users: which tools to use, and which is the most accurate model for a given TF? Therefore, the first section of this thesis investigates the motif assessment problem: how scoring functions, choice and processing of benchmark data, and statistics used in evaluation affect motif ranking. This analysis revealed that TF motif quality assessment requires a systematic comparative analysis, and that scoring functions used have a TF-specific effect on motif ranking. These results advised the design of a Motif Assessment and Ranking Suite MARS, supported by PBM and ChIP-seq benchmark data and an extensive collection of PWM motifs. MARS implements consistency, enrichment, and scoring and classification-based motif evaluation algorithms. Transcription factor binding is also influenced and determined by contextual factors: chromatin accessibility, competition or cooperation with other TFs, cell line or condition specificity, binding locality (e.g. proximity to transcription start sites) and the shape of the binding site (DNA-shape). In vitro techniques do not capture such context; therefore, this thesis also combines PBM and DNase-seq data using a comparative k-mer enrichment approach that compares open chromatin with genome-wide prevalence, achieving a modest performance improvement when benchmarked on ChIP-seq data. Finally, since statistical and probabilistic methods cannot capture all the information that determine binding, a machine learning approach (XGBooost) was implemented to investigate how the features contribute to TF specificity and occupancy. This combinatorial approach improves the predictive ability of TF specificity models with the most predictive feature being chromatin accessibility, while the DNA-shape and conservation information all significantly improve on the baseline model of k-mer and DNase data. The results and the tools introduced in this thesis are useful for systematic comparative analysis (via MARS) and a combinatorial approach to modelling TF binding specificity, including appropriate feature engineering practices for machine learning modelling.
- Full Text:
- Authors: Kibet, Caleb Kipkurui
- Date: 2017
- Subjects: Transcription factors , Transcription factors -- Data processing , Motif Assessment and Ranking Suite
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21185 , http://hdl.handle.net/10962/6838
- Description: The major contributions of this thesis are addressing the need for an objective quality evaluation of a transcription factor binding model, demonstrating the value of the tools developed to this end and elucidating how in vitro and in vivo information can be utilized to improve TF binding specificity models. Accurate elucidation of TF binding specificity remains an ongoing challenge in gene regulatory research. Several in vitro and in vivo experimental techniques have been developed followed by a proliferation of algorithms, and ultimately, the binding models. This increase led to a choice problem for the end users: which tools to use, and which is the most accurate model for a given TF? Therefore, the first section of this thesis investigates the motif assessment problem: how scoring functions, choice and processing of benchmark data, and statistics used in evaluation affect motif ranking. This analysis revealed that TF motif quality assessment requires a systematic comparative analysis, and that scoring functions used have a TF-specific effect on motif ranking. These results advised the design of a Motif Assessment and Ranking Suite MARS, supported by PBM and ChIP-seq benchmark data and an extensive collection of PWM motifs. MARS implements consistency, enrichment, and scoring and classification-based motif evaluation algorithms. Transcription factor binding is also influenced and determined by contextual factors: chromatin accessibility, competition or cooperation with other TFs, cell line or condition specificity, binding locality (e.g. proximity to transcription start sites) and the shape of the binding site (DNA-shape). In vitro techniques do not capture such context; therefore, this thesis also combines PBM and DNase-seq data using a comparative k-mer enrichment approach that compares open chromatin with genome-wide prevalence, achieving a modest performance improvement when benchmarked on ChIP-seq data. Finally, since statistical and probabilistic methods cannot capture all the information that determine binding, a machine learning approach (XGBooost) was implemented to investigate how the features contribute to TF specificity and occupancy. This combinatorial approach improves the predictive ability of TF specificity models with the most predictive feature being chromatin accessibility, while the DNA-shape and conservation information all significantly improve on the baseline model of k-mer and DNase data. The results and the tools introduced in this thesis are useful for systematic comparative analysis (via MARS) and a combinatorial approach to modelling TF binding specificity, including appropriate feature engineering practices for machine learning modelling.
- Full Text: