Nonlinear optical properties of metal free and nickel binuclear phthalocyanines
- Kabwe, Kapambwe P, Louzada, Marcel, Britton, Jonathan, Olomola, Temitope O, Nyokong, Tebello, Khene, Samson M
- Authors: Kabwe, Kapambwe P , Louzada, Marcel , Britton, Jonathan , Olomola, Temitope O , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186846 , vital:44539 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.05.003"
- Description: This work employs the open and closed Z-scan aperture technique to comparatively study the nonlinear optical (NLO) properties of nickel and metal free 4-tert-butylphenoxy phthalocyanine, biphenyl bridged bis-4-tert-butylphenoxy phthalocyanine and naphthalene bridged bis-4-tert-butylphenoxy phthalocyanine. Density functional theory (DFT) calculations of dipolar and octupolar ( J=1 and J=3) contribution were determined theoretically from hyper-Rayleigh scattering (HRS) response ( HRS) values.
- Full Text:
- Date Issued: 2019
- Authors: Kabwe, Kapambwe P , Louzada, Marcel , Britton, Jonathan , Olomola, Temitope O , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186846 , vital:44539 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.05.003"
- Description: This work employs the open and closed Z-scan aperture technique to comparatively study the nonlinear optical (NLO) properties of nickel and metal free 4-tert-butylphenoxy phthalocyanine, biphenyl bridged bis-4-tert-butylphenoxy phthalocyanine and naphthalene bridged bis-4-tert-butylphenoxy phthalocyanine. Density functional theory (DFT) calculations of dipolar and octupolar ( J=1 and J=3) contribution were determined theoretically from hyper-Rayleigh scattering (HRS) response ( HRS) values.
- Full Text:
- Date Issued: 2019
Nonlinear optical responses of carbazole-substituted phthalocyanines conjugated to graphene quantum dots and in thin films
- Majeed, Shereen A, Nwaji, Njemuwa, Mack, John, Nyokong, Tebello, Makhseed, Saad
- Authors: Majeed, Shereen A , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello , Makhseed, Saad
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186938 , vital:44549 , xlink:href="https://doi.org/10.1016/j.jlumin.2019.04.034"
- Description: Three different phthalocyanine complexes substituted with carbazoles were conjugated to graphene quantum dots (GQDs) through π–π stacking. The morphologies, sizes, and crystallinities of the nanoconjugates were determined using Raman spectroscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The nonlinear optical (NLO) properties of the metallophthalocyanines alone and when conjugated to the GQD nanomaterial in different solvents, as well as after having been embedded in thin films, were studied. The effects of the different substituents and solvents on the NLO properties of the metallophthalocyanines were evaluated. Enhancements in the photophysical properties of the complexes upon conjugation with the nanomaterial were observed. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields, and triplet lifetimes were measured for the complexes, and for their conjugates in DMSO.
- Full Text:
- Date Issued: 2019
- Authors: Majeed, Shereen A , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello , Makhseed, Saad
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186938 , vital:44549 , xlink:href="https://doi.org/10.1016/j.jlumin.2019.04.034"
- Description: Three different phthalocyanine complexes substituted with carbazoles were conjugated to graphene quantum dots (GQDs) through π–π stacking. The morphologies, sizes, and crystallinities of the nanoconjugates were determined using Raman spectroscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The nonlinear optical (NLO) properties of the metallophthalocyanines alone and when conjugated to the GQD nanomaterial in different solvents, as well as after having been embedded in thin films, were studied. The effects of the different substituents and solvents on the NLO properties of the metallophthalocyanines were evaluated. Enhancements in the photophysical properties of the complexes upon conjugation with the nanomaterial were observed. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields, and triplet lifetimes were measured for the complexes, and for their conjugates in DMSO.
- Full Text:
- Date Issued: 2019
Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
Nostalgia in reimagining the past: the subjectivity of memory in the representation of history. A textual analysis of Rehad Desai's documentary films
- Authors: Dlamini, Philani Vincent
- Date: 2019
- Subjects: Documentary films -- South Africa , Nostalgia in motion pictures Nostalgia in mass media
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/45183 , vital:38261
- Description: South Africa occupies a unique space in terms of the decolonization of the continent of Africa. While massive projects of decolonization where happening across the continent, South Africa was subjected to a conservative and racialised project of segregation. This arrested development makes for an interesting anachronism in South Africa as disconcerting “Third- World” and “First-World” economies emerged creating an anomalous temporality. I was born just a month before the inimitable Ruth First was unceremoniously assassinated in Mozambique in 1982. While further South, one of the most underreported conflicts of apartheid South Africa was in its nascent stages no further than a kilometer away from my house. I am referring of course to the violent clashes between factions of both the Inkatha Freedom Party (IFP) and the African National Congress (ANC), played in the men’s hostel of the third largest township in the country, Umlazi, South of Durban. These would only come to have meaning to me later, when I was at university. I mention these cultural and perhaps socio-political artefacts in so far as they relate to the kind of environment that lead to this research enquiry. Which is to say that as social beings, we are in fact products of the things that affect the social environment that we exist in. This is not a new idea. What is particularly interesting for this enquiry is the eclecticism of the emblems that survive to shapes one’s own identity and perception of the world around them. Within the above stated mini-biography lies a complex matrix of emotions and extrapolated meanings mediated through a conflicted and negotiated understanding of what the social history of South Africa meant for my own personal history. This paper is an attempt to think through articulations of time as they are constituted by future-orientated subjectivities extending back to varied pasts. It does so by exploring a recent work of black South African self-writing, Jacob Dlamini’s Native Nostalgia (2009). Considering the text’s treatment of time, I argue that porous conceptions of temporality open up possibilities for self-enunciation. What Paul Gilroy has described as “the signs of sameness” (2000, 101). Meaning that these could be quantified and as such researchable and in fact applied across various cultural texts (including but not limited to film). The body of work from South African documentary filmmaker Rehad Desai provides an interesting case study to examine Jacob Dlamini’s thematic pre-occupations with nostalgia. Nostalgia here is used to see if such pre-occupations can be applied to a filmic body of work. Desai’s body of work is interesting to this enquiry because it almost exclusively deals with the temporalities of South Africa as “refracted through the prism of the past”. By this I mean Desai through his work appears to reflect on South Africa’s storied past as it affects current happenings. It is the intention of this paper to argue that Desai deals with his subject (the evolution of the South African political landscape) in similar terms to the way Jacob Dlamini explores the notion of reflective nostalgia.
- Full Text:
- Date Issued: 2019
- Authors: Dlamini, Philani Vincent
- Date: 2019
- Subjects: Documentary films -- South Africa , Nostalgia in motion pictures Nostalgia in mass media
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/45183 , vital:38261
- Description: South Africa occupies a unique space in terms of the decolonization of the continent of Africa. While massive projects of decolonization where happening across the continent, South Africa was subjected to a conservative and racialised project of segregation. This arrested development makes for an interesting anachronism in South Africa as disconcerting “Third- World” and “First-World” economies emerged creating an anomalous temporality. I was born just a month before the inimitable Ruth First was unceremoniously assassinated in Mozambique in 1982. While further South, one of the most underreported conflicts of apartheid South Africa was in its nascent stages no further than a kilometer away from my house. I am referring of course to the violent clashes between factions of both the Inkatha Freedom Party (IFP) and the African National Congress (ANC), played in the men’s hostel of the third largest township in the country, Umlazi, South of Durban. These would only come to have meaning to me later, when I was at university. I mention these cultural and perhaps socio-political artefacts in so far as they relate to the kind of environment that lead to this research enquiry. Which is to say that as social beings, we are in fact products of the things that affect the social environment that we exist in. This is not a new idea. What is particularly interesting for this enquiry is the eclecticism of the emblems that survive to shapes one’s own identity and perception of the world around them. Within the above stated mini-biography lies a complex matrix of emotions and extrapolated meanings mediated through a conflicted and negotiated understanding of what the social history of South Africa meant for my own personal history. This paper is an attempt to think through articulations of time as they are constituted by future-orientated subjectivities extending back to varied pasts. It does so by exploring a recent work of black South African self-writing, Jacob Dlamini’s Native Nostalgia (2009). Considering the text’s treatment of time, I argue that porous conceptions of temporality open up possibilities for self-enunciation. What Paul Gilroy has described as “the signs of sameness” (2000, 101). Meaning that these could be quantified and as such researchable and in fact applied across various cultural texts (including but not limited to film). The body of work from South African documentary filmmaker Rehad Desai provides an interesting case study to examine Jacob Dlamini’s thematic pre-occupations with nostalgia. Nostalgia here is used to see if such pre-occupations can be applied to a filmic body of work. Desai’s body of work is interesting to this enquiry because it almost exclusively deals with the temporalities of South Africa as “refracted through the prism of the past”. By this I mean Desai through his work appears to reflect on South Africa’s storied past as it affects current happenings. It is the intention of this paper to argue that Desai deals with his subject (the evolution of the South African political landscape) in similar terms to the way Jacob Dlamini explores the notion of reflective nostalgia.
- Full Text:
- Date Issued: 2019
Nostalgia in reimagining the past: the subjectivity of memory in the representation of history. a textual analysis of Rehad Desai's documentary films
- Authors: Dlamini, Philani Vincent
- Date: 2019
- Subjects: Documentary films
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44591 , vital:38159
- Description: South Africa occupies a unique space in terms of the decolonization of the continent of Africa. While massive projects of decolonization where happening across the continent, South Africa was subjected to a conservative and racialised project of segregation. This arrested development makes for an interesting anachronism in South Africa as disconcerting “ThirdWorld” and “First-World” economies emerged creating an anomalous temporality. I was born just a month before the inimitable Ruth First was unceremoniously assassinated in Mozambique in 1982. While further South, one of the most underreported conflicts of apartheid South Africa was in its nascent stages no further than a kilometer away from my house. I am referring of course to the violent clashes between factions of both the Inkatha Freedom Party (IFP) and the African National Congress (ANC), played in the men’s hostel of the third largest township in the country, Umlazi, South of Durban. These would only come to have meaning to me later, when I was at university. I mention these cultural and perhaps socio-political artefacts in so far as they relate to the kind of environment that lead to this research enquiry. Which is to say that as social beings, we are in fact products of the things that affect the social environment that we exist in. This is not a new idea. What is particularly interesting for this enquiry is the eclecticism of the emblems that survive to shapes one’s own identity and perception of the world around them. Within the above stated mini-biography lies a complex matrix of emotions and extrapolated meanings mediated through a conflicted and negotiated understanding of what the social history of South Africa meant for my own personal history. This paper is an attempt to think through articulations of time as they are constituted by future-orientated subjectivities extending back to varied pasts. It does so by exploring a recent work of black South African self-writing, Jacob Dlamini’s Native Nostalgia (2009). Considering the text’s treatment of time, I argue that porous conceptions of temporality open up possibilities for self-enunciation. What Paul Gilroy has described as “the signs of sameness” (2000, 101). Meaning that these could be quantified and as such researchable and in fact applied across various cultural texts (including but not limited to film). The body of work from South African documentary filmmaker Rehad Desai provides an interesting case study to examine Jacob Dlamini’s thematic pre-occupations with nostalgia. Nostalgia here is used to see if such pre-occupations can be applied to a filmic body of work. Desai’s body of work is interesting to this enquiry because it almost exclusively deals with the temporalities of South Africa as “refracted through the prism of the past”. By this I mean Desai through his work appears to reflect on South Africa’s storied past as it affects current happenings. It is the intention of this paper to argue that Desai deals with his subject (the evolution of the South African political landscape) in similar terms to the way Jacob Dlamini explores the notion of reflective nostalgia.
- Full Text:
- Date Issued: 2019
- Authors: Dlamini, Philani Vincent
- Date: 2019
- Subjects: Documentary films
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44591 , vital:38159
- Description: South Africa occupies a unique space in terms of the decolonization of the continent of Africa. While massive projects of decolonization where happening across the continent, South Africa was subjected to a conservative and racialised project of segregation. This arrested development makes for an interesting anachronism in South Africa as disconcerting “ThirdWorld” and “First-World” economies emerged creating an anomalous temporality. I was born just a month before the inimitable Ruth First was unceremoniously assassinated in Mozambique in 1982. While further South, one of the most underreported conflicts of apartheid South Africa was in its nascent stages no further than a kilometer away from my house. I am referring of course to the violent clashes between factions of both the Inkatha Freedom Party (IFP) and the African National Congress (ANC), played in the men’s hostel of the third largest township in the country, Umlazi, South of Durban. These would only come to have meaning to me later, when I was at university. I mention these cultural and perhaps socio-political artefacts in so far as they relate to the kind of environment that lead to this research enquiry. Which is to say that as social beings, we are in fact products of the things that affect the social environment that we exist in. This is not a new idea. What is particularly interesting for this enquiry is the eclecticism of the emblems that survive to shapes one’s own identity and perception of the world around them. Within the above stated mini-biography lies a complex matrix of emotions and extrapolated meanings mediated through a conflicted and negotiated understanding of what the social history of South Africa meant for my own personal history. This paper is an attempt to think through articulations of time as they are constituted by future-orientated subjectivities extending back to varied pasts. It does so by exploring a recent work of black South African self-writing, Jacob Dlamini’s Native Nostalgia (2009). Considering the text’s treatment of time, I argue that porous conceptions of temporality open up possibilities for self-enunciation. What Paul Gilroy has described as “the signs of sameness” (2000, 101). Meaning that these could be quantified and as such researchable and in fact applied across various cultural texts (including but not limited to film). The body of work from South African documentary filmmaker Rehad Desai provides an interesting case study to examine Jacob Dlamini’s thematic pre-occupations with nostalgia. Nostalgia here is used to see if such pre-occupations can be applied to a filmic body of work. Desai’s body of work is interesting to this enquiry because it almost exclusively deals with the temporalities of South Africa as “refracted through the prism of the past”. By this I mean Desai through his work appears to reflect on South Africa’s storied past as it affects current happenings. It is the intention of this paper to argue that Desai deals with his subject (the evolution of the South African political landscape) in similar terms to the way Jacob Dlamini explores the notion of reflective nostalgia.
- Full Text:
- Date Issued: 2019
Novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine: an investigation of their inclusion ability
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
Novel potential antimalarials through drug repurposing and multitargeting: a Computational Approach
- Diallo, Bakary N, Lobb, Kevin A, Tastan Bishop, Özlem
- Authors: Diallo, Bakary N , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162676 , vital:40972 , https://doi.org/10.21955/aasopenres.1114955.1
- Description: This study aims to identify potential antimalarials from Food and Drug Administration (FDA) approved drugs.
- Full Text:
- Date Issued: 2019
- Authors: Diallo, Bakary N , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162676 , vital:40972 , https://doi.org/10.21955/aasopenres.1114955.1
- Description: This study aims to identify potential antimalarials from Food and Drug Administration (FDA) approved drugs.
- Full Text:
- Date Issued: 2019
Nutritional and pharmacological profile of moringa oleifera lam. Leaves cultivated in the South African ecotype
- Authors: Yako, Zomsa
- Date: 2019
- Subjects: Moringa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14605 , vital:40021
- Description: Moringa oleifera Lam. is native to the Indian ecotype, which has become naturalized in many tropic and subtropic regions worldwide, thus a great variation in the bioactive compounds of the plant is recorded. The introduction of Moringa oleifera to South Africa occurred in the turn of the twentieth century with the aim of combating malnourishment, aiding health and fostering economic development. Therefore, this study was conducted with the aim of evaluating and authenticating the nutritional parameters, essential oil and bioactive components found in the various solvent extracts of Moringa oleifera leaves cultivated in the South African ecotype. It also elucidated some of the plants medicinal properties by investigating the antioxidant and antibacterial properties of the plant. The essential oil of the leaves was extracted using two methods (solvent free microwave extraction and hydrodistillation) and analysed using Gas Chromotography/Mass Spectrometer. The safety profile of the leaves was investigated using brine shrimp model. The results from the study revealed that Moringa oleifera leaves cultivated in South Africa were rich in crude protein levels (28.72%) and carbohydrate (28.84%). Among the minerals tested for, the leaves contained high content of calcium (1603.33 mg/100 g), potassium (1690 mg/100 g), zinc (13.03 mg/100 g) and iron (21.13 mg/100 g). The vitamin E content had the highest concentration (89.43 mg/100 g) among the vitamins evaluated. The leaves of Moringa oleifera had low quantities of antinutrients in relation to minerals, thus ensuring nutrients availability. This study identified 15 fatty acids in the dried leaves of Moringa. The highest fatty acid detected were polyunsaturated fatty acids, linoleic acid (56.36) and alpha-linolenic acid (687.58), 7 of the fatty acids were saturated fatty acids, though relatively low besides stearic acid. 15 amino acids were present, 7 of which were essential amino acids, namely; threonine, tyrosine, methionine, valine, phenylalanine, isoleucine and leucine. vi Among the phytochemicals evaluated, the aqueous extract gave the highest total phenolic content (21.01 ± 2.315 mg GAE/g), the acetone extract gave the highest proanthocyanidin (15.33 3.5 mg CE/g) and flavonoid contents (25.04±3.28 mg QE/g), while saponin and alkaloid contents were 27.73 ± 9.97% and 7.32 ± 2.73 % respectively. All the extracts exhibited high radical scavenging power against the 2,2- diphenyl-1-picrylhydrazyl radical with an IC50 less than 0.025 mg/mL. Aqueous extract gave the highest capacity based on ABTS and TAC assays with IC50 of 0.074 mg/ mL and 0.055 mg/mL respectively. Ethanol extract exhibited the least antioxidant capacity among the extracts, as well as the least antimicrobial activity on both Gram −ve and Gram +ve bacteria with all its minimum inhibitory concentration values greater than 5 mg/mL. The acetone extract exhibited the strongest antimicrobial activity among the extracts. A total of 8 and 24 chemical compounds were found from the solvent-free microwave extracted and hydrodistilled oils, respectively. The major components found from hydrodistillation were 2-Hexanal (16.37%), Nonanal (6.09%), 5 9-undecadien-2-one 6, 10 dimethyl- (e) - (8.01%), trans-beta-Ionone (8.02%) and octadecane (9.67%). For the solvent free microwave extracted oil, Benzene acetaldehyde (5.68%), Octadecane, Pentacosane and Eicosane which were 11.03%, were the major components. Toxicity evaluation revealed that mortality was time dependent. As the exposure period increased, mortality kept increasing. The hatching success of the cysts in acetone, aqueous and ethanol extracts were 35.7, 33.6 and 35.2% respectively. Acetone extract showed the most prominent hatching success. Hatchability and lethality were in a concentration dependent fashion. Among the extracts, acetone extract exhibited the highest lethality (12.3%) to the nauplii, followed by ethanol (10.9%), then aqueous (5.6%) extracts. All the results obtained from this study suggest that Moringa has the potential of eradicating malnutrition and aid health. It contains the necessary nutritional and bioactive compounds and the leaves proved not to be toxic at the levels (0.0625 – 1 mg/mL) tested.
- Full Text:
- Date Issued: 2019
- Authors: Yako, Zomsa
- Date: 2019
- Subjects: Moringa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14605 , vital:40021
- Description: Moringa oleifera Lam. is native to the Indian ecotype, which has become naturalized in many tropic and subtropic regions worldwide, thus a great variation in the bioactive compounds of the plant is recorded. The introduction of Moringa oleifera to South Africa occurred in the turn of the twentieth century with the aim of combating malnourishment, aiding health and fostering economic development. Therefore, this study was conducted with the aim of evaluating and authenticating the nutritional parameters, essential oil and bioactive components found in the various solvent extracts of Moringa oleifera leaves cultivated in the South African ecotype. It also elucidated some of the plants medicinal properties by investigating the antioxidant and antibacterial properties of the plant. The essential oil of the leaves was extracted using two methods (solvent free microwave extraction and hydrodistillation) and analysed using Gas Chromotography/Mass Spectrometer. The safety profile of the leaves was investigated using brine shrimp model. The results from the study revealed that Moringa oleifera leaves cultivated in South Africa were rich in crude protein levels (28.72%) and carbohydrate (28.84%). Among the minerals tested for, the leaves contained high content of calcium (1603.33 mg/100 g), potassium (1690 mg/100 g), zinc (13.03 mg/100 g) and iron (21.13 mg/100 g). The vitamin E content had the highest concentration (89.43 mg/100 g) among the vitamins evaluated. The leaves of Moringa oleifera had low quantities of antinutrients in relation to minerals, thus ensuring nutrients availability. This study identified 15 fatty acids in the dried leaves of Moringa. The highest fatty acid detected were polyunsaturated fatty acids, linoleic acid (56.36) and alpha-linolenic acid (687.58), 7 of the fatty acids were saturated fatty acids, though relatively low besides stearic acid. 15 amino acids were present, 7 of which were essential amino acids, namely; threonine, tyrosine, methionine, valine, phenylalanine, isoleucine and leucine. vi Among the phytochemicals evaluated, the aqueous extract gave the highest total phenolic content (21.01 ± 2.315 mg GAE/g), the acetone extract gave the highest proanthocyanidin (15.33 3.5 mg CE/g) and flavonoid contents (25.04±3.28 mg QE/g), while saponin and alkaloid contents were 27.73 ± 9.97% and 7.32 ± 2.73 % respectively. All the extracts exhibited high radical scavenging power against the 2,2- diphenyl-1-picrylhydrazyl radical with an IC50 less than 0.025 mg/mL. Aqueous extract gave the highest capacity based on ABTS and TAC assays with IC50 of 0.074 mg/ mL and 0.055 mg/mL respectively. Ethanol extract exhibited the least antioxidant capacity among the extracts, as well as the least antimicrobial activity on both Gram −ve and Gram +ve bacteria with all its minimum inhibitory concentration values greater than 5 mg/mL. The acetone extract exhibited the strongest antimicrobial activity among the extracts. A total of 8 and 24 chemical compounds were found from the solvent-free microwave extracted and hydrodistilled oils, respectively. The major components found from hydrodistillation were 2-Hexanal (16.37%), Nonanal (6.09%), 5 9-undecadien-2-one 6, 10 dimethyl- (e) - (8.01%), trans-beta-Ionone (8.02%) and octadecane (9.67%). For the solvent free microwave extracted oil, Benzene acetaldehyde (5.68%), Octadecane, Pentacosane and Eicosane which were 11.03%, were the major components. Toxicity evaluation revealed that mortality was time dependent. As the exposure period increased, mortality kept increasing. The hatching success of the cysts in acetone, aqueous and ethanol extracts were 35.7, 33.6 and 35.2% respectively. Acetone extract showed the most prominent hatching success. Hatchability and lethality were in a concentration dependent fashion. Among the extracts, acetone extract exhibited the highest lethality (12.3%) to the nauplii, followed by ethanol (10.9%), then aqueous (5.6%) extracts. All the results obtained from this study suggest that Moringa has the potential of eradicating malnutrition and aid health. It contains the necessary nutritional and bioactive compounds and the leaves proved not to be toxic at the levels (0.0625 – 1 mg/mL) tested.
- Full Text:
- Date Issued: 2019
Nutritional quality of sausage made with edible meat waste and the perception of consumers on offal product in Eastern Cape Province, South Africa
- Authors: Oluwasegun, Babatunde Alao
- Date: 2019
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/19021 , vital:40094
- Description: Meat processing at the abattoir provides meat by product and waste while, the major part of the muscle which constitutes a third is edible. The edible by products (EBP) of meat have a notable position in our day-to-day life and are used in diverse forms. However, the quality of offal meat may differ according to intrinsic and extrinsic attributes that may occasionally be shaped by the attitude of consumers towards the products. Therefore, the first objective of this thesis focused on features that might influence consumer preferences and their perception of offal meat. A total of 202 consumers from three Municipalities in Amathole District were randomly sampled using exponential nondiscriminative snowball sampling. Data were gathered through a structured questionnaire containing open ended and closed ended questions. The study showed that consumers were more influenced by the freshness, price and availability of the product and these factors are used to determine the purchase outlet. Differences were observed in the offal meat consumption between the age groups. Age groups 25-34 (29.7%) and 35-44 (27.4%) showed the highest offal meat consumption, while the decline was observed in age groups of 55-64 (11.9%), 65- 74 (5.9%) and 75-85 (0.01%) respectively. The most preferred purchase point for offal meat in this study was in butcheries. However, it was observed that the factors influencing offal consumption in Amathole District were similar to meat consumption except that, offals were mainly purchased at butcher shops. The second objective in this study was to determine the sensory characteristics and consumer acceptance of sausages with 10% fat, 30% edible meat waste and 50% edible meat waste. Sensory descriptive attributes such as appearance, texture, colour, taste, flavour and overall acceptance of the sausage were evaluated by sensory panel (n = 60). The sensory panel comprised of students from undergraduates, post-graduates, post-doctoral fellows and lecturers at the University of Fort Hare. The findings of the study indicated that 50% replacement of xiii edible meat waste was similar to the commercial 10% fat with regard to several sensory attributes and pooled liking. Therefore, the utilization of the edible meat waste in production of sausages has the potential to increase profitability in meat industry and minimise meat waste in the industry. However, the cooking method that was more acceptable to consumers in this study was using the microwave as compared to oven-grilling. Furthermore, the effects of different cooking methods (microwave and oven-grilling) on proximate and mineral composition of the formulated sausages were determined. However, the cooking process appeared to have a significant effect on most of the minerals in the sausage. The cooking methods had a significant effect at P <0.01 on the nutrients composition of the formulated sausage. It was observed that the nutritional values of the sausage was better preserved after the cooking process due to higher mean values obtained after cooking. The mean values for calcium (173.1, 221.76, 231.29), potassium (444.57, 158.58, 156.67), magnesium (84.43, 257.97, 127.27), zinc (52.94, 35.27, 27.13), copper (8.8, 7.07, 4.44), manganese (8.74, 0.65, 0.08), sodium (589.42, 604.45, 529.79) and iron (63.3, 85.38, 74.81) in cooked. And the mean values for calcium (286.18, 132.18, 114.79), potassium (206.64, 113.83, 207.81), magnesium (189.89, 33.97, 48.11), zinc (61.05, 28.09, 26.44), copper (2.92, 2.73, 3.89), manganese (1.42, 0.11, 0.35), sodium (566.47, 530.79, 527.35) and iron (77.56, 58.68, 45.42) in uncooked sausage varied greatly among the treatments. Although, the disparities in the mineral content may be attributed to the different edible meat waste from different parts of the cattle which are either from feedlot or pastured based. In regard to the results obtained from proximate and mineral composition, microwave cooking method was found to be the best cooking technique for healthy eating. Finally, the effect of frying with two different oils (sunflower oil and olive oil) on the fatty acid composition of sausage made with edible meat waste was examined. The results revealed that beef sausage containing 70% edible meat wastes and 30% beef (T1) had a higher fat content xiv (25.7%±0.83%) than other treatments. On the other hand, beef sausage fortified with 10% fat and 90% beef (T3) had the lowest fat content but highest FFDM (55.85±0.57%) and moisture content (69.15±0.62) than other treatments. Despite the increase in omega-3: omega-6 fatty acid ratio in the sausage treatments after cooking, the mean value of omega-3: omega-6 fatty acid ratio was greater than 1:5 (0.2) which is within the FAO/WHO recommended range. The omega-3: omega-6 association is well-known for its importance in the diet because it is a key factor for balanced eicosanoid production in the living organism. The significant reduction in saturated fatty acids after cooking showed that there could also be a positive influence on the human health if consumed. Therefore, it may be concluded from the findings of the study that sausage made with edible meat waste as fat replacer is safe for human consumption.
- Full Text:
- Date Issued: 2019
- Authors: Oluwasegun, Babatunde Alao
- Date: 2019
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/19021 , vital:40094
- Description: Meat processing at the abattoir provides meat by product and waste while, the major part of the muscle which constitutes a third is edible. The edible by products (EBP) of meat have a notable position in our day-to-day life and are used in diverse forms. However, the quality of offal meat may differ according to intrinsic and extrinsic attributes that may occasionally be shaped by the attitude of consumers towards the products. Therefore, the first objective of this thesis focused on features that might influence consumer preferences and their perception of offal meat. A total of 202 consumers from three Municipalities in Amathole District were randomly sampled using exponential nondiscriminative snowball sampling. Data were gathered through a structured questionnaire containing open ended and closed ended questions. The study showed that consumers were more influenced by the freshness, price and availability of the product and these factors are used to determine the purchase outlet. Differences were observed in the offal meat consumption between the age groups. Age groups 25-34 (29.7%) and 35-44 (27.4%) showed the highest offal meat consumption, while the decline was observed in age groups of 55-64 (11.9%), 65- 74 (5.9%) and 75-85 (0.01%) respectively. The most preferred purchase point for offal meat in this study was in butcheries. However, it was observed that the factors influencing offal consumption in Amathole District were similar to meat consumption except that, offals were mainly purchased at butcher shops. The second objective in this study was to determine the sensory characteristics and consumer acceptance of sausages with 10% fat, 30% edible meat waste and 50% edible meat waste. Sensory descriptive attributes such as appearance, texture, colour, taste, flavour and overall acceptance of the sausage were evaluated by sensory panel (n = 60). The sensory panel comprised of students from undergraduates, post-graduates, post-doctoral fellows and lecturers at the University of Fort Hare. The findings of the study indicated that 50% replacement of xiii edible meat waste was similar to the commercial 10% fat with regard to several sensory attributes and pooled liking. Therefore, the utilization of the edible meat waste in production of sausages has the potential to increase profitability in meat industry and minimise meat waste in the industry. However, the cooking method that was more acceptable to consumers in this study was using the microwave as compared to oven-grilling. Furthermore, the effects of different cooking methods (microwave and oven-grilling) on proximate and mineral composition of the formulated sausages were determined. However, the cooking process appeared to have a significant effect on most of the minerals in the sausage. The cooking methods had a significant effect at P <0.01 on the nutrients composition of the formulated sausage. It was observed that the nutritional values of the sausage was better preserved after the cooking process due to higher mean values obtained after cooking. The mean values for calcium (173.1, 221.76, 231.29), potassium (444.57, 158.58, 156.67), magnesium (84.43, 257.97, 127.27), zinc (52.94, 35.27, 27.13), copper (8.8, 7.07, 4.44), manganese (8.74, 0.65, 0.08), sodium (589.42, 604.45, 529.79) and iron (63.3, 85.38, 74.81) in cooked. And the mean values for calcium (286.18, 132.18, 114.79), potassium (206.64, 113.83, 207.81), magnesium (189.89, 33.97, 48.11), zinc (61.05, 28.09, 26.44), copper (2.92, 2.73, 3.89), manganese (1.42, 0.11, 0.35), sodium (566.47, 530.79, 527.35) and iron (77.56, 58.68, 45.42) in uncooked sausage varied greatly among the treatments. Although, the disparities in the mineral content may be attributed to the different edible meat waste from different parts of the cattle which are either from feedlot or pastured based. In regard to the results obtained from proximate and mineral composition, microwave cooking method was found to be the best cooking technique for healthy eating. Finally, the effect of frying with two different oils (sunflower oil and olive oil) on the fatty acid composition of sausage made with edible meat waste was examined. The results revealed that beef sausage containing 70% edible meat wastes and 30% beef (T1) had a higher fat content xiv (25.7%±0.83%) than other treatments. On the other hand, beef sausage fortified with 10% fat and 90% beef (T3) had the lowest fat content but highest FFDM (55.85±0.57%) and moisture content (69.15±0.62) than other treatments. Despite the increase in omega-3: omega-6 fatty acid ratio in the sausage treatments after cooking, the mean value of omega-3: omega-6 fatty acid ratio was greater than 1:5 (0.2) which is within the FAO/WHO recommended range. The omega-3: omega-6 association is well-known for its importance in the diet because it is a key factor for balanced eicosanoid production in the living organism. The significant reduction in saturated fatty acids after cooking showed that there could also be a positive influence on the human health if consumed. Therefore, it may be concluded from the findings of the study that sausage made with edible meat waste as fat replacer is safe for human consumption.
- Full Text:
- Date Issued: 2019
Observing cosmic reionization with PAPER: polarized foreground simulations and all sky images
- Authors: Nunhokee, Chuneeta Devi
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Epoch of reionization -- Research , Hydrogen -- Spectra , Radio interferometers
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68203 , vital:29218
- Description: The Donald C. Backer Precision Array to Probe the Epoch of Reionization (PAPER, Parsons et al., 2010) was built with an aim to detect the redshifted 21 cm Hydrogen line, which is likely the best probe of thermal evolution of the intergalactic medium and reionization of neutral Hydrogen in our Universe. Observations of the 21 cm signal are challenged by bright astrophysical foregrounds and systematics that require precise modeling in order to extract the cosmological signal. In particular, the instrumental leakage of polarized foregrounds may contaminate the 21 cm power spectrum. In this work, we developed a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra and used it to predict contaminations in observations. We find the leakage due to a population of point sources to be higher than the diffuse Galactic emission – for which we can predict minimal contaminations at k>0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.
- Full Text:
- Date Issued: 2019
- Authors: Nunhokee, Chuneeta Devi
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Epoch of reionization -- Research , Hydrogen -- Spectra , Radio interferometers
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68203 , vital:29218
- Description: The Donald C. Backer Precision Array to Probe the Epoch of Reionization (PAPER, Parsons et al., 2010) was built with an aim to detect the redshifted 21 cm Hydrogen line, which is likely the best probe of thermal evolution of the intergalactic medium and reionization of neutral Hydrogen in our Universe. Observations of the 21 cm signal are challenged by bright astrophysical foregrounds and systematics that require precise modeling in order to extract the cosmological signal. In particular, the instrumental leakage of polarized foregrounds may contaminate the 21 cm power spectrum. In this work, we developed a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra and used it to predict contaminations in observations. We find the leakage due to a population of point sources to be higher than the diffuse Galactic emission – for which we can predict minimal contaminations at k>0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.
- Full Text:
- Date Issued: 2019
Occurrence, feeding ecology, and population structure of two dolphin species, Tursiops aduncus and Delphinus delphis, off the Wild Coast of South Africa
- Authors: Caputo, Michelle Anne
- Date: 2019
- Subjects: Delphinus -- South Africa-- Kwazulu-Natal -- Ecology , Tursoops -- South Africa-- Kwazulu-Natal -- Ecology , Delphinus -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Tursoops -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Dolphins -- South Africa-- Kwazulu-Natal , Delphinus -- South Africa-- Kwazulu-Natal -- Behavior , Tursoops -- South Africa-- Kwazulu-Natal -- Behavior , Marine ecology -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115612 , vital:34197
- Description: Dolphins are apex predators and their movements, foraging activities and population dynamics play an important role in shaping their environment. Understanding their occurrence, movement patterns, and trophic ecology is essential to their conservation, especially as they are considered sentinel species. The Wild Coast of South Africa’s Eastern Cape, is characterized by the annual sardine (Sardinops sagax) run, which serves as an important foraging event for apex predators, including Indo-Pacific bottlenose (Tursiops aduncus) and long-beaked common dolphins (Delphinus delphis). Despite the ecological significance of this event, no dedicated surveys for these species have previously been conducted in this area. The main objectives of this research were to: investigate long-term occurrence of dolphins during the sardine run to determine if there have been any changes over the past 19 years, as has been predicted from common dolphin dietary investigations and anecdotal evidence; to determine short-term occurrence and movement patterns of selected inshore delphinids within the area, which is characterized by three marine protected areas (MPAs); and to use stable isotope analyses to determine trophic relationships and population structure of bottlenose and common dolphins within the region. Long-term data consisted of 131 opportunistic aerial surveys conducted between May and July over the period 1996 to 2014. Results from these surveys indicate that common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p=0.0343). Bottlenose dolphins, demonstrated no such trend (p=0.916). For both species, greater majority (> 70% of total counts) of sightings were made inside the MPAs. Short-term boat-based surveys were conducted three times a year between June 2014 and December 2016, contributing to a total of 47 days of surveys divided into three locations: Amathole, Hluleka, and Pondoland, each containing a MPA. Density and group size data were analyzed for both species and photographic identification analysis was performed for photographs of bottlenose dolphin dorsal fins. Results indicate that animal and sighting density did not differ temporally (bottlenose dolphin: sighting density – p=0.398, individual density –p=0.781; common dolphin: sighting density –p=0.472, individual density – p=0.204). Environmental factors (sea surface temperature, depth, substrate, and distance from shore) appeared to have limited effect on individual and sighting density and group size for both species (p>0.05). Photographic identification of bottlenose dolphins resulted in 2149 individuals, with a 11.8% resighting rate, with the highest resighting rate within the Pondoland MPA (16.1%). The resighting count did not differ temporally between monthly survey based on generalized linear models (p=0.866), but did differ between study areas (p<0.0001). These results provide the first evidence of the occurrence of both species of dolphin off the Wild Coast, as they were sighted in this region in all survey months. There was no trend in density based on temporal or environmental factors, which suggests other factors are influencing their occurrence. Resightings of bottlenose dolphins within the area suggest that there is some degree of residency, though the majority of animals were only sighted on a single occasion and there was no plateau in the discovery curve. A total of 256 biopsy samples (bottlenose dolphins =128; common dolphins=128) were collected during boat-based surveys. Bottlenose dolphin samples were also collected from adjacent areas to the southwest (Algoa Bay, n=22) and northeast (KwaZulu-Natal (KZN), n=20) of the Wild Coast to investigate similarities and differences between these areas. Despite a high degree of niche overlap between the two species (41%), common dolphins fed with a broader niche (standard ellipse area probability 0.89) than bottlenose dolphins in the summer and a narrower niche in the winter (probability 0.94). There was a clear spatial variation in the diet of bottlenose dolphins along the coast, with individuals from Algoa Bay and Amathole demonstrating 0% niche overlap with individuals from KZN, but the mechanism for these differences remains unclear as other species from South African waters demonstrate a strong southwest to northeast gradient in nitrogen for the Eastern Cape coastline. This research provides valuable baseline information regarding dolphins off the Wild Coast of South Africa, which remained largely unknown. My results indicate that bottlenose dolphins may be more resident in the Wild Coast than previous predicted, and confirm that common dolphins are highly mobile in this area.
- Full Text:
- Date Issued: 2019
- Authors: Caputo, Michelle Anne
- Date: 2019
- Subjects: Delphinus -- South Africa-- Kwazulu-Natal -- Ecology , Tursoops -- South Africa-- Kwazulu-Natal -- Ecology , Delphinus -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Tursoops -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Dolphins -- South Africa-- Kwazulu-Natal , Delphinus -- South Africa-- Kwazulu-Natal -- Behavior , Tursoops -- South Africa-- Kwazulu-Natal -- Behavior , Marine ecology -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115612 , vital:34197
- Description: Dolphins are apex predators and their movements, foraging activities and population dynamics play an important role in shaping their environment. Understanding their occurrence, movement patterns, and trophic ecology is essential to their conservation, especially as they are considered sentinel species. The Wild Coast of South Africa’s Eastern Cape, is characterized by the annual sardine (Sardinops sagax) run, which serves as an important foraging event for apex predators, including Indo-Pacific bottlenose (Tursiops aduncus) and long-beaked common dolphins (Delphinus delphis). Despite the ecological significance of this event, no dedicated surveys for these species have previously been conducted in this area. The main objectives of this research were to: investigate long-term occurrence of dolphins during the sardine run to determine if there have been any changes over the past 19 years, as has been predicted from common dolphin dietary investigations and anecdotal evidence; to determine short-term occurrence and movement patterns of selected inshore delphinids within the area, which is characterized by three marine protected areas (MPAs); and to use stable isotope analyses to determine trophic relationships and population structure of bottlenose and common dolphins within the region. Long-term data consisted of 131 opportunistic aerial surveys conducted between May and July over the period 1996 to 2014. Results from these surveys indicate that common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p=0.0343). Bottlenose dolphins, demonstrated no such trend (p=0.916). For both species, greater majority (> 70% of total counts) of sightings were made inside the MPAs. Short-term boat-based surveys were conducted three times a year between June 2014 and December 2016, contributing to a total of 47 days of surveys divided into three locations: Amathole, Hluleka, and Pondoland, each containing a MPA. Density and group size data were analyzed for both species and photographic identification analysis was performed for photographs of bottlenose dolphin dorsal fins. Results indicate that animal and sighting density did not differ temporally (bottlenose dolphin: sighting density – p=0.398, individual density –p=0.781; common dolphin: sighting density –p=0.472, individual density – p=0.204). Environmental factors (sea surface temperature, depth, substrate, and distance from shore) appeared to have limited effect on individual and sighting density and group size for both species (p>0.05). Photographic identification of bottlenose dolphins resulted in 2149 individuals, with a 11.8% resighting rate, with the highest resighting rate within the Pondoland MPA (16.1%). The resighting count did not differ temporally between monthly survey based on generalized linear models (p=0.866), but did differ between study areas (p<0.0001). These results provide the first evidence of the occurrence of both species of dolphin off the Wild Coast, as they were sighted in this region in all survey months. There was no trend in density based on temporal or environmental factors, which suggests other factors are influencing their occurrence. Resightings of bottlenose dolphins within the area suggest that there is some degree of residency, though the majority of animals were only sighted on a single occasion and there was no plateau in the discovery curve. A total of 256 biopsy samples (bottlenose dolphins =128; common dolphins=128) were collected during boat-based surveys. Bottlenose dolphin samples were also collected from adjacent areas to the southwest (Algoa Bay, n=22) and northeast (KwaZulu-Natal (KZN), n=20) of the Wild Coast to investigate similarities and differences between these areas. Despite a high degree of niche overlap between the two species (41%), common dolphins fed with a broader niche (standard ellipse area probability 0.89) than bottlenose dolphins in the summer and a narrower niche in the winter (probability 0.94). There was a clear spatial variation in the diet of bottlenose dolphins along the coast, with individuals from Algoa Bay and Amathole demonstrating 0% niche overlap with individuals from KZN, but the mechanism for these differences remains unclear as other species from South African waters demonstrate a strong southwest to northeast gradient in nitrogen for the Eastern Cape coastline. This research provides valuable baseline information regarding dolphins off the Wild Coast of South Africa, which remained largely unknown. My results indicate that bottlenose dolphins may be more resident in the Wild Coast than previous predicted, and confirm that common dolphins are highly mobile in this area.
- Full Text:
- Date Issued: 2019
Of Record:
- Docrat, Zakeera, Kaschula, Russell H
- Authors: Docrat, Zakeera , Kaschula, Russell H
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/174772 , vital:42508 , ISBN 9781928480174
- Description: This chapter aims to analyse the 2017 resolution to adopt English as the monolingual language of record that affects high courts in South Africa with reference to the constitutional language framework. We investigate whether the legislative framework enables the Chief Justice to change the language of record; and how a monolingual language of record affects the official status of languages other than English. In this judicial context, the language of record is taken to mean the language, which is used officially to litigate in courts of law, the language in which the judicial process is conducted, the language in which the proceedings are recorded, as well as that of written judgments.
- Full Text:
- Date Issued: 2019
- Authors: Docrat, Zakeera , Kaschula, Russell H
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/174772 , vital:42508 , ISBN 9781928480174
- Description: This chapter aims to analyse the 2017 resolution to adopt English as the monolingual language of record that affects high courts in South Africa with reference to the constitutional language framework. We investigate whether the legislative framework enables the Chief Justice to change the language of record; and how a monolingual language of record affects the official status of languages other than English. In this judicial context, the language of record is taken to mean the language, which is used officially to litigate in courts of law, the language in which the judicial process is conducted, the language in which the proceedings are recorded, as well as that of written judgments.
- Full Text:
- Date Issued: 2019
Of sacred crossroads: cultural studies and the Sacred A special issue edited by Sonjah Stanley Niaah
- Authors: Stanley Niaah, Sonjah
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146066 , vital:38492 , https://0-doi.org.wam.seals.ac.za/10.1515/culture-2019-0047
- Description: The Seventh International Association for Cultural Studies Crossroads Conference, held in 2008 at the University of the West Indies, in Mona, Jamaica, was staged for the first time with an overarching theme. Based on the cultural, spiritual and geographical diversity of the Caribbean region, the local conference organizing team insisted that the conference needed to reflect key aspects of the space. Consequently, the theme selected was “Of Sacred Crossroads”. The conference call for papers asked for a consideration of issues surrounding the dialogue between humanity and spirituality. In the face of increasing materialism and consumerism, as well as the prevailing emphasis on science and technology in contemporary society, participants celebrated the intangible heritage of humankind--that found in religion, art, dance, song, oratory, healing, re-creation, performance, ritual, belief systems, ethics, globalization and communication, among others.
- Full Text:
- Date Issued: 2019
Of sacred crossroads: cultural studies and the Sacred A special issue edited by Sonjah Stanley Niaah
- Authors: Stanley Niaah, Sonjah
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146066 , vital:38492 , https://0-doi.org.wam.seals.ac.za/10.1515/culture-2019-0047
- Description: The Seventh International Association for Cultural Studies Crossroads Conference, held in 2008 at the University of the West Indies, in Mona, Jamaica, was staged for the first time with an overarching theme. Based on the cultural, spiritual and geographical diversity of the Caribbean region, the local conference organizing team insisted that the conference needed to reflect key aspects of the space. Consequently, the theme selected was “Of Sacred Crossroads”. The conference call for papers asked for a consideration of issues surrounding the dialogue between humanity and spirituality. In the face of increasing materialism and consumerism, as well as the prevailing emphasis on science and technology in contemporary society, participants celebrated the intangible heritage of humankind--that found in religion, art, dance, song, oratory, healing, re-creation, performance, ritual, belief systems, ethics, globalization and communication, among others.
- Full Text:
- Date Issued: 2019
On the study of the performance of Photovoltaic power plants
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
On-site evaluation of smoking, alcohol consumption and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa
- Adedokun, Aanuoluwa Odunayo, Ter Goon, Daniel, Owolabi, Eyitayo Omolara, Adeniyi, Oladele Vincent, Ajayi, Anthony Idowu
- Authors: Adedokun, Aanuoluwa Odunayo , Ter Goon, Daniel , Owolabi, Eyitayo Omolara , Adeniyi, Oladele Vincent , Ajayi, Anthony Idowu
- Date: 2019
- Subjects: Alcohol use , Substance use , Commercial drivers
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/5086 , vital:44345 , https://doi.org/10.5539/gjhs.v11n2p110
- Description: Commercial drivers have been identified as eliciting behaviours that promote non- communicable diseases and road traffic accidents. The aim of the study is to determine the prevalence and pattern of alcohol use, smoking and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa. A cross-sectional study was conducted among 403 commercial drivers using the face-to-face interviews method. The WHO STEPwise questionnaire was used to obtain the demographic data, self-reported rate of alcohol consumption, tobacco use and physical inactivity. The participants’ mean age was 43.3 ± 12.5 years. About 30% of the participants were daily smokers, 37% consumed alcohol regularly and only 18% were physically active, whilst 82% were physically inactive. The prevalence of alcohol use, smoking and physical inactivity is high among commercial drivers in East London. Workplace health education on the health effects of these lifestyles’ risky behaviours on individuals and the general public should be given to the drivers.
- Full Text:
- Date Issued: 2019
- Authors: Adedokun, Aanuoluwa Odunayo , Ter Goon, Daniel , Owolabi, Eyitayo Omolara , Adeniyi, Oladele Vincent , Ajayi, Anthony Idowu
- Date: 2019
- Subjects: Alcohol use , Substance use , Commercial drivers
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/5086 , vital:44345 , https://doi.org/10.5539/gjhs.v11n2p110
- Description: Commercial drivers have been identified as eliciting behaviours that promote non- communicable diseases and road traffic accidents. The aim of the study is to determine the prevalence and pattern of alcohol use, smoking and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa. A cross-sectional study was conducted among 403 commercial drivers using the face-to-face interviews method. The WHO STEPwise questionnaire was used to obtain the demographic data, self-reported rate of alcohol consumption, tobacco use and physical inactivity. The participants’ mean age was 43.3 ± 12.5 years. About 30% of the participants were daily smokers, 37% consumed alcohol regularly and only 18% were physically active, whilst 82% were physically inactive. The prevalence of alcohol use, smoking and physical inactivity is high among commercial drivers in East London. Workplace health education on the health effects of these lifestyles’ risky behaviours on individuals and the general public should be given to the drivers.
- Full Text:
- Date Issued: 2019
Ontological Model for Xhosa Beadwork in Marginalised Rural Communities: A Case of the Eastern Cape
- Authors: Tinarwo, Loyd
- Date: 2019
- Subjects: Ontology Beadwork
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15749 , vital:40516
- Description: In South Africa, computational ontologies have gained traction and are increasingly viewed as one of the viable solutions to address the problem of fragmented and unstructured nature of indigenous knowledge (IK) particularly in the marginalized rural communities. The continual existence of IK in tacit form has impeded the use of IK as a potential resource that can catalyze socio-economic and cultural development in South Africa. This study was, therefore, designed to address part of this challenge by developing a Xhosa Beadwork Ontology (XBO) with the goal of structuring the domain knowledge into a reusable body of knowledge. Such a reusable body of knowledge promotes efficient sharing of a common understanding of Xhosa Beadwork in a computational form. The XBO is in OWL 2 DL. The development of the XBO was informed by the NeOn methodology and the iterativeincremental ontology development life cycle within the ambit of Action Research (AR). The XBO was developed around personal ornamentation Xhosa Beadwork consisting of Necklace, Headband, Armlet, Waistband, Bracelet, and Anklet. In this study, the XBO was evaluated focused on ascertaining that the created ontology is a comprehensive representation of the Xhosa Beadwork and is of the required standard. In addition, the XBO was documented into a human understandable and readable resource and was published. The outcome of the study has indicated that the XBO is an adequate, shareable and reusable semantic artifact that can indeed support the formalization and preservation of IK in the domain of Xhosa Beadwork
- Full Text:
- Date Issued: 2019
- Authors: Tinarwo, Loyd
- Date: 2019
- Subjects: Ontology Beadwork
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15749 , vital:40516
- Description: In South Africa, computational ontologies have gained traction and are increasingly viewed as one of the viable solutions to address the problem of fragmented and unstructured nature of indigenous knowledge (IK) particularly in the marginalized rural communities. The continual existence of IK in tacit form has impeded the use of IK as a potential resource that can catalyze socio-economic and cultural development in South Africa. This study was, therefore, designed to address part of this challenge by developing a Xhosa Beadwork Ontology (XBO) with the goal of structuring the domain knowledge into a reusable body of knowledge. Such a reusable body of knowledge promotes efficient sharing of a common understanding of Xhosa Beadwork in a computational form. The XBO is in OWL 2 DL. The development of the XBO was informed by the NeOn methodology and the iterativeincremental ontology development life cycle within the ambit of Action Research (AR). The XBO was developed around personal ornamentation Xhosa Beadwork consisting of Necklace, Headband, Armlet, Waistband, Bracelet, and Anklet. In this study, the XBO was evaluated focused on ascertaining that the created ontology is a comprehensive representation of the Xhosa Beadwork and is of the required standard. In addition, the XBO was documented into a human understandable and readable resource and was published. The outcome of the study has indicated that the XBO is an adequate, shareable and reusable semantic artifact that can indeed support the formalization and preservation of IK in the domain of Xhosa Beadwork
- Full Text:
- Date Issued: 2019
Optical limiting and femtosecond pump-probe transient absorbance properties of a 3, 5-distyrylBODIPY dye
- Ngoy, Bokolombe P, May, Aviwe K, Mack, John, Nyokong, Tebello
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186835 , vital:44538 , xlink:href="https://doi.org/10.3389/fchem.2019.00740"
- Description: The optical limiting (OL) properties of a 3,5-di-p-benzyloxystyrylBODIPY dye with an p-acetamidophenyl moiety at the meso-position have been investigated by using the open-aperture Z-scan technique at 532 nm with 10 ns laser pulses. There is a ca. 140 nm red shift of the main spectral band to 644 nm relative to the corresponding BODIPY core dye, due to the incorporation of p-benzyloxystyryl groups at the 3,5-positions. As a result, there is relatively weak absorbance across most of the visible region under ambient light conditions. Analysis of the observed reverse saturable absorbance (RSA) profiles demonstrates that the dye is potentially suitable for use in optical limiting applications as has been reported previously for other 3,5-distyrylBODIPY dyes. Time-resolved transient absorption spectroscopy and kinetic studies with femtosecond and nanosecond scale laser pulses provide the first direct spectral evidence that excited state absorption (ESA) from the S1 state is responsible for the observed OL properties.
- Full Text:
- Date Issued: 2019
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186835 , vital:44538 , xlink:href="https://doi.org/10.3389/fchem.2019.00740"
- Description: The optical limiting (OL) properties of a 3,5-di-p-benzyloxystyrylBODIPY dye with an p-acetamidophenyl moiety at the meso-position have been investigated by using the open-aperture Z-scan technique at 532 nm with 10 ns laser pulses. There is a ca. 140 nm red shift of the main spectral band to 644 nm relative to the corresponding BODIPY core dye, due to the incorporation of p-benzyloxystyryl groups at the 3,5-positions. As a result, there is relatively weak absorbance across most of the visible region under ambient light conditions. Analysis of the observed reverse saturable absorbance (RSA) profiles demonstrates that the dye is potentially suitable for use in optical limiting applications as has been reported previously for other 3,5-distyrylBODIPY dyes. Time-resolved transient absorption spectroscopy and kinetic studies with femtosecond and nanosecond scale laser pulses provide the first direct spectral evidence that excited state absorption (ESA) from the S1 state is responsible for the observed OL properties.
- Full Text:
- Date Issued: 2019
Optimising construction project role-player performance
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019
OR Tambo Lifetime Achiever Ubuntu Awards
- Date: 2019 , 2022-10-03
- Subjects: Bam, Brigalia , Bam, Brigalia -- Awards
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/56733 , vital:57151
- Description: Dr. Brigalia Bam received OR Tambo Lifetime Achiever Ubuntu Awards. It was awarded by the State in October 2019. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2019
- Date: 2019 , 2022-10-03
- Subjects: Bam, Brigalia , Bam, Brigalia -- Awards
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/56733 , vital:57151
- Description: Dr. Brigalia Bam received OR Tambo Lifetime Achiever Ubuntu Awards. It was awarded by the State in October 2019. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2019
Oral narratives as intertexts in selected Nigerian films
- Authors: Usman, Joshua
- Date: 2019
- Subjects: Folk literature -- Nigeria , Oral tradition -- Nigeria Motion pictures -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43721 , vital:37038
- Description: This research into the interface between orality and Nigerian film builds on previous scholarly works in the field (Ladebo (1992), Onabajo and M’Bayo (2009), Omolola (2013), Ezeigbo (2013), Mgbemere (2015) and Onzuike (2016)). Evident from these studies is the prevalence of recurring patterns of oral narratives in Nigerian film. The aim of this study is to consider the following research questions: Do film producers/directors adopt the use of oral narratives in Nigerian film texts? How do oral narratives translate into films? What is the rate of recurrence of oral narratives in Nigerian films? Do oral narratives aesthetically influence the quality of Nigerian films? For the purpose of this study a selection of nine Nigerian films (three each from the Yoruba, Hausa and Igbo groups). These films are analysed as primary texts to show the occurrence of elements of orature and oral narratives. Underpinning such analysis is the theory of intertextuality as coined by the French linguist Julia Kristeva. Kristeva sees the text as “intertextuality […] within the text of society and history” (Kristeva, 1980: 37). This approach is augmented by the views of Greenblatt on New Historicism, which implies literature should be studied and interpreted within the context of the history of the author and cultural/social context. The nine films under discussion are considered within their cultural/social context.
- Full Text:
- Date Issued: 2019
- Authors: Usman, Joshua
- Date: 2019
- Subjects: Folk literature -- Nigeria , Oral tradition -- Nigeria Motion pictures -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43721 , vital:37038
- Description: This research into the interface between orality and Nigerian film builds on previous scholarly works in the field (Ladebo (1992), Onabajo and M’Bayo (2009), Omolola (2013), Ezeigbo (2013), Mgbemere (2015) and Onzuike (2016)). Evident from these studies is the prevalence of recurring patterns of oral narratives in Nigerian film. The aim of this study is to consider the following research questions: Do film producers/directors adopt the use of oral narratives in Nigerian film texts? How do oral narratives translate into films? What is the rate of recurrence of oral narratives in Nigerian films? Do oral narratives aesthetically influence the quality of Nigerian films? For the purpose of this study a selection of nine Nigerian films (three each from the Yoruba, Hausa and Igbo groups). These films are analysed as primary texts to show the occurrence of elements of orature and oral narratives. Underpinning such analysis is the theory of intertextuality as coined by the French linguist Julia Kristeva. Kristeva sees the text as “intertextuality […] within the text of society and history” (Kristeva, 1980: 37). This approach is augmented by the views of Greenblatt on New Historicism, which implies literature should be studied and interpreted within the context of the history of the author and cultural/social context. The nine films under discussion are considered within their cultural/social context.
- Full Text:
- Date Issued: 2019