Nonlinear optical studies of phthalocyanines and their conjugates with nanomaterials
- Authors: Sanusi, Sikiru Olukayode
- Date: 2015
- Subjects: Phthalocyanines , Nonlinear optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4545 , http://hdl.handle.net/10962/d1017925
- Description: A number of metallophthalocyanines (MPcs) and metal-free phthalocyanines (H₂Pcs) have been synthesized and characterized using various characterization tools such as ¹H-NMR, TOF mass spectrometry, FT-IR, UV-visible spectrophotometry and CHNS elemental analysis. Some of the MPcs were covalently linked to nanomaterials such as silica nanoparticles (SiNPs), single-walled carbon nanotubes (SWCNTs), magnetite nanoparticles (MNPs) and quantum dots (QDs), or embedded in polymer thin-films using poly(methyl methacrylate) (PMMA) and poly(acrylic acid) (PAA) as the polymer sources. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), thermogravimetry analysis and X-ray diffractometry. The nonlinear optical (NLO) properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. In general, most of the investigated MPcs showed good optical limiting behaviors, except for a few, like the non-peripherally-substituted 2-pyridyloxy phthalocyanines, which showed inhibited NLO response as a result of the ring-strain effects. The absence of a metal center was found to greatly reduce the inherent high nonlinearities expected of some of the phthalocyanine complexes. The octaphenoxy derivatives (61a – 61e) were found to exhibit reverse saturable absorption (RSA) that depends on the singlet-singlet transitions, hence making them less reliable optical limiters. The optical limiting properties of the MPcs were improved in the presence of nanomaterials such as the QDs, MNPs and SWCNTs, with MPc-QDs showing the best optical limiting behavior of the three. SiNPs have no significant effect on the optical limiting behavior of the MPcs. The optical limiting properties of the MPcs were greatly enhanced in the presence of PMMA or PAA polymers. The PAA polymer showed better optical limiting behavior compared to PMMA
- Full Text:
- Authors: Sanusi, Sikiru Olukayode
- Date: 2015
- Subjects: Phthalocyanines , Nonlinear optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4545 , http://hdl.handle.net/10962/d1017925
- Description: A number of metallophthalocyanines (MPcs) and metal-free phthalocyanines (H₂Pcs) have been synthesized and characterized using various characterization tools such as ¹H-NMR, TOF mass spectrometry, FT-IR, UV-visible spectrophotometry and CHNS elemental analysis. Some of the MPcs were covalently linked to nanomaterials such as silica nanoparticles (SiNPs), single-walled carbon nanotubes (SWCNTs), magnetite nanoparticles (MNPs) and quantum dots (QDs), or embedded in polymer thin-films using poly(methyl methacrylate) (PMMA) and poly(acrylic acid) (PAA) as the polymer sources. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), thermogravimetry analysis and X-ray diffractometry. The nonlinear optical (NLO) properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. In general, most of the investigated MPcs showed good optical limiting behaviors, except for a few, like the non-peripherally-substituted 2-pyridyloxy phthalocyanines, which showed inhibited NLO response as a result of the ring-strain effects. The absence of a metal center was found to greatly reduce the inherent high nonlinearities expected of some of the phthalocyanine complexes. The octaphenoxy derivatives (61a – 61e) were found to exhibit reverse saturable absorption (RSA) that depends on the singlet-singlet transitions, hence making them less reliable optical limiters. The optical limiting properties of the MPcs were improved in the presence of nanomaterials such as the QDs, MNPs and SWCNTs, with MPc-QDs showing the best optical limiting behavior of the three. SiNPs have no significant effect on the optical limiting behavior of the MPcs. The optical limiting properties of the MPcs were greatly enhanced in the presence of PMMA or PAA polymers. The PAA polymer showed better optical limiting behavior compared to PMMA
- Full Text:
Nonlinear optical studies of phthalocyanines and triazatetrabenzcorroles in solution and in thin films
- Authors: Mkhize, Nhlakanipho Colin
- Date: 2015
- Subjects: Phthalocyanines , Thin films , Nonlinear optics , Phosphorus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4542 , http://hdl.handle.net/10962/d1017922
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compared with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting intensity of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behaviour than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution. Novel phosphorus triazatetrabenzcorroles (TBC) tetrasubstituted at the α- and β- and octa substituted at the β- positions of the peripheral fused benzene rings with t-butylphenoxy substituents were prepared and characterized. The effects of the substituents and the missing aza-nitrogen on the electronic structures and optical spectroscopy are investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties were investigated to examine whether the lower symmetry that results from the direct pyrrole-pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. Novel phosphorus phthalocyanines, analogous to the triazatetrabenzcorroles were also investigated. Due to their high photodegradation quantum yield however, only the fluorescence quantum yields and lifetimes were able to be determined.
- Full Text:
- Authors: Mkhize, Nhlakanipho Colin
- Date: 2015
- Subjects: Phthalocyanines , Thin films , Nonlinear optics , Phosphorus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4542 , http://hdl.handle.net/10962/d1017922
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compared with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting intensity of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behaviour than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution. Novel phosphorus triazatetrabenzcorroles (TBC) tetrasubstituted at the α- and β- and octa substituted at the β- positions of the peripheral fused benzene rings with t-butylphenoxy substituents were prepared and characterized. The effects of the substituents and the missing aza-nitrogen on the electronic structures and optical spectroscopy are investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties were investigated to examine whether the lower symmetry that results from the direct pyrrole-pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. Novel phosphorus phthalocyanines, analogous to the triazatetrabenzcorroles were also investigated. Due to their high photodegradation quantum yield however, only the fluorescence quantum yields and lifetimes were able to be determined.
- Full Text:
Nudus amor formam non amat artificem : representations of gender in elegiac discourse
- Authors: Evans, Philippa A
- Date: 2015
- Subjects: Elegiac poetry , Gender identity in literature , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Benjamin, Jessica , Mulvey, Laura , Tibullus , Propertius, Sextus , Sulpicia, active 1st century B.C. , Ovid, 43 B.C. - 17 or 18 A.D. Metamorphoses. Liber 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3654 , http://hdl.handle.net/10962/d1017895
- Description: This thesis explores the representation of gender, desire, and identity in elegiac discourse. It does so through the lens of post‐structural and psychoanalytic theory, referring to the works of Michel Foucault, Judith Butler, Jessica Benjamin, and Laura Mulvey in their analyses of power, gender performativity, and subjectivity. Within this thesis, these concepts are applied primarily to the works of Tibullus, Propertius, and Sulpicia, ultimately demonstrating that the three love elegists seek, in their poetry, to construct subversive discourses which destabilise the categories by which gender and identity were determined in Augustan Rome. This discussion is supplemented by the investigation of Ovid’s use of elegiac discourse in Book 10 of his Metamorphoses, and the way in which it both comments upon Augustan love elegy and demonstrates a number of parallels with its thematic content. This thesis focuses especially on the representation of power relations within elegiac discourse, the various levels on which such relations operate and, finally, the possibilities for the contestation of and resistance to power, in addition to the motivations that might lie behind the poet‐lover’s frequent attraction and submission to it.
- Full Text:
- Authors: Evans, Philippa A
- Date: 2015
- Subjects: Elegiac poetry , Gender identity in literature , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Benjamin, Jessica , Mulvey, Laura , Tibullus , Propertius, Sextus , Sulpicia, active 1st century B.C. , Ovid, 43 B.C. - 17 or 18 A.D. Metamorphoses. Liber 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3654 , http://hdl.handle.net/10962/d1017895
- Description: This thesis explores the representation of gender, desire, and identity in elegiac discourse. It does so through the lens of post‐structural and psychoanalytic theory, referring to the works of Michel Foucault, Judith Butler, Jessica Benjamin, and Laura Mulvey in their analyses of power, gender performativity, and subjectivity. Within this thesis, these concepts are applied primarily to the works of Tibullus, Propertius, and Sulpicia, ultimately demonstrating that the three love elegists seek, in their poetry, to construct subversive discourses which destabilise the categories by which gender and identity were determined in Augustan Rome. This discussion is supplemented by the investigation of Ovid’s use of elegiac discourse in Book 10 of his Metamorphoses, and the way in which it both comments upon Augustan love elegy and demonstrates a number of parallels with its thematic content. This thesis focuses especially on the representation of power relations within elegiac discourse, the various levels on which such relations operate and, finally, the possibilities for the contestation of and resistance to power, in addition to the motivations that might lie behind the poet‐lover’s frequent attraction and submission to it.
- Full Text:
Observed correlations of unsolicited ip traffic across five distinct network telescopes
- Irwin, Barry V W, Nkhumeleni, T
- Authors: Irwin, Barry V W , Nkhumeleni, T
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428569 , vital:72521 , https://www.jstor.org/stable/26502727
- Description: Using network telescopes to monitor unused IP address space provides a favourable environment for researchers to study and detect malware, denial of service, and scanning activities on the Internet. This research focuses on comparative and correlation analysis of traffic activity across five IPv4 network telescopes, each with an aperture size of /24 over a 12-month period. Time series representations of the traffic activity observed on these sensors were constructed. Using the cross- and auto-correlation methods of time series analysis, sensor data was quantitatively analysed with the resulting correlation of network telescopes’ traffic activity found to be moderate to high, dependent on grouping.
- Full Text:
- Authors: Irwin, Barry V W , Nkhumeleni, T
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428569 , vital:72521 , https://www.jstor.org/stable/26502727
- Description: Using network telescopes to monitor unused IP address space provides a favourable environment for researchers to study and detect malware, denial of service, and scanning activities on the Internet. This research focuses on comparative and correlation analysis of traffic activity across five IPv4 network telescopes, each with an aperture size of /24 over a 12-month period. Time series representations of the traffic activity observed on these sensors were constructed. Using the cross- and auto-correlation methods of time series analysis, sensor data was quantitatively analysed with the resulting correlation of network telescopes’ traffic activity found to be moderate to high, dependent on grouping.
- Full Text:
Observed correlations of unsolicited network traffic over five distinct IPv4 netblocks
- Nkhumeleni, Thiswilondi M, Irwin, Barry V W
- Authors: Nkhumeleni, Thiswilondi M , Irwin, Barry V W
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430408 , vital:72689 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: Using network telescopes to monitor unused IP address space provides a favorable environment for researchers to study and detect malware, denial of service and scanning activities within global IPv4 address space. This research focuses on comparative and correlation analysis of traffic activity across the network of telescope sensors. Analysis is done using data collected over a 12 month period on five network telescopes each with an aperture size of/24, operated in disjoint IPv4 address space. These were considered as two distinct groupings. Time series’ representing time-based traffic activity observed on these sensors was constructed. Using the cross-and auto-correlation methods of time series analysis, moderate correlation of traffic activity was achieved between telescope sensors in each category. Weak to moderate correlation was calculated when comparing category A and category B network telescopes’ datasets. Results were significantly improved by considering TCP traffic separately. Moderate to strong correlation coefficients in each category were calculated when using TCP traffic only. UDP traffic analysis showed weaker correlation between sensors, however the uniformity of ICMP traffic showed correlation of traffic activity across all sensors. The results confirmed the visual observation of traffic relativity in telescope sensors within the same category and quantitatively analyzed the correlation of network telescopes’ traffic activity.
- Full Text:
- Authors: Nkhumeleni, Thiswilondi M , Irwin, Barry V W
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430408 , vital:72689 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: Using network telescopes to monitor unused IP address space provides a favorable environment for researchers to study and detect malware, denial of service and scanning activities within global IPv4 address space. This research focuses on comparative and correlation analysis of traffic activity across the network of telescope sensors. Analysis is done using data collected over a 12 month period on five network telescopes each with an aperture size of/24, operated in disjoint IPv4 address space. These were considered as two distinct groupings. Time series’ representing time-based traffic activity observed on these sensors was constructed. Using the cross-and auto-correlation methods of time series analysis, moderate correlation of traffic activity was achieved between telescope sensors in each category. Weak to moderate correlation was calculated when comparing category A and category B network telescopes’ datasets. Results were significantly improved by considering TCP traffic separately. Moderate to strong correlation coefficients in each category were calculated when using TCP traffic only. UDP traffic analysis showed weaker correlation between sensors, however the uniformity of ICMP traffic showed correlation of traffic activity across all sensors. The results confirmed the visual observation of traffic relativity in telescope sensors within the same category and quantitatively analyzed the correlation of network telescopes’ traffic activity.
- Full Text:
Occupational health and safety and industrial relations in the South African construction industry : case studies of selected construction firms in Grahamstown
- Nene, Sinenhlanhla Sindisiwe
- Authors: Nene, Sinenhlanhla Sindisiwe
- Date: 2015
- Subjects: Industrial safety -- South Africa , Industrial relations -- South Africa , Construction industry -- South Africa -- Grahamstown , Management -- Employee participation
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3401 , http://hdl.handle.net/10962/d1018663
- Description: The construction industry is one of the most dangerous industries in the world, with many workplace fatalities every day. The existence of legislation that governs Occupational Health and Safety (OHS) is an intervention to ensure that all governments, employers and employees play their part in establishing and implementing policies that will help secure healthy and safe working environments. The study is qualitative and with the help of an interview guide, semistructured interviews were used to collect the data. The respondents were selected using purposive and snowball sampling methods. Ten managers from ten (five small, five large) construction firms, two employees from each firm, and the OHS inspector from the Department of Labour in Grahamstown were interviewed. Having explored management’s practices, communication methods, training and distribution of information, employee representation and participation, and industrial relations, several conclusions were reached. During the study it was found that there are a number of obstacles that are hampering effective OHS in the construction industry. Some of these include; management’s lack of commitment to a participatory approach in OHS decision-making, limited resources to invest adequately in OHS, and the lack of sufficient trade union involvement. In addition, we know very little about OHS in the construction industry, and the mere existence of OHS legislation does not help reduce the risks associated with construction work, especially when there is a shortage of skilled personnel to enforce the legislation and regulations.
- Full Text:
- Authors: Nene, Sinenhlanhla Sindisiwe
- Date: 2015
- Subjects: Industrial safety -- South Africa , Industrial relations -- South Africa , Construction industry -- South Africa -- Grahamstown , Management -- Employee participation
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3401 , http://hdl.handle.net/10962/d1018663
- Description: The construction industry is one of the most dangerous industries in the world, with many workplace fatalities every day. The existence of legislation that governs Occupational Health and Safety (OHS) is an intervention to ensure that all governments, employers and employees play their part in establishing and implementing policies that will help secure healthy and safe working environments. The study is qualitative and with the help of an interview guide, semistructured interviews were used to collect the data. The respondents were selected using purposive and snowball sampling methods. Ten managers from ten (five small, five large) construction firms, two employees from each firm, and the OHS inspector from the Department of Labour in Grahamstown were interviewed. Having explored management’s practices, communication methods, training and distribution of information, employee representation and participation, and industrial relations, several conclusions were reached. During the study it was found that there are a number of obstacles that are hampering effective OHS in the construction industry. Some of these include; management’s lack of commitment to a participatory approach in OHS decision-making, limited resources to invest adequately in OHS, and the lack of sufficient trade union involvement. In addition, we know very little about OHS in the construction industry, and the mere existence of OHS legislation does not help reduce the risks associated with construction work, especially when there is a shortage of skilled personnel to enforce the legislation and regulations.
- Full Text:
On active layer processes and landforms in western Dronning Maud Land, Antarctica
- Authors: Scott, David Alan
- Date: 2015
- Subjects: Landforms -- Antarctica -- Queen Maud Land , Permafrost -- Antarctica -- Queen Maud Land , Permafrost -- Thermal properties -- Antarctica -- Queen Maud Land , Climatic changes -- Antarctica -- Queen Maud Land , Cryosphere , Drone aircraft -- Antarctica -- Queen Maud Land , 3-D modeling
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4893 , http://hdl.handle.net/10962/d1019757
- Description: Permafrost is a variable in Antarctic terrestrial ecosystems, and the role it plays in the cryosphere is not well understood. There is much still to be learnt about the thermal state, physical properties, thickness and age of permafrost in Western Dronning Maud Land (WDML). Active layer dynamics and observed change over time have the potential to improve our knowledge of climate change. Understanding the effects of a warming climate on permafrost can also be of benefit to infrastructure, especially in areas with a large amount of frozen ground such as Scandinavia, Canada and Russia. Active layer and permafrost dynamics of WDML, Antarctica, are presented and discussed using data from six study sites, namely the Robertskollen, Vesleskarvet, Flarjuven, Grunehogna, Slettjfell nunataks and the Troll research station in the Jutulsessen area. Ground and ambient air temperature, as well as ground moisture data were collected for each site. An inventory of active layer and permafrost landforms was compiled, as were the frequency of cycles over the zero-degree isotherm, and the depth of the active layer. Furthermore, 3D models, geo-referenced maps and Digital Elevation Models were created of study areas with the use of an Unmanned Aerial Vehicle (UAV). Polygonal features are the most common landscape feature and are common to most of the study sites. Robertskollen has the deepest active layer at over 66cm and Slettfjell the shallowest at 9cm. A maximum recorded air temperature of 8.76°C (10/11/2014) occurred at Troll with the second highest maximum of 6.77°C (22/12/2010) recorded at Vesleskarvet. Robertskollen has the highest observable biological growth and a maximum recorded ground temperature of 22.84°C (10/01/2014). Troll and Valterkulten, registered the second and third highest ground temperatures respectively. The high ground Temperature observed for Robertskollen may be ascribed to it being the lowest altitude site. The highest number of cycles over the zero-degree isotherm was observed at Troll (11.01%), followed by Robertskollen (10.99%). For relatively warm areas, such as Robertskollen it is recommended that two metre borehole loggers are installed in order to capture a detailed understanding of the active layer. The UAV proved to be a beneficial tool for capturing aerial photographs for post fieldwork analysis and 3D modelling.
- Full Text:
- Authors: Scott, David Alan
- Date: 2015
- Subjects: Landforms -- Antarctica -- Queen Maud Land , Permafrost -- Antarctica -- Queen Maud Land , Permafrost -- Thermal properties -- Antarctica -- Queen Maud Land , Climatic changes -- Antarctica -- Queen Maud Land , Cryosphere , Drone aircraft -- Antarctica -- Queen Maud Land , 3-D modeling
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4893 , http://hdl.handle.net/10962/d1019757
- Description: Permafrost is a variable in Antarctic terrestrial ecosystems, and the role it plays in the cryosphere is not well understood. There is much still to be learnt about the thermal state, physical properties, thickness and age of permafrost in Western Dronning Maud Land (WDML). Active layer dynamics and observed change over time have the potential to improve our knowledge of climate change. Understanding the effects of a warming climate on permafrost can also be of benefit to infrastructure, especially in areas with a large amount of frozen ground such as Scandinavia, Canada and Russia. Active layer and permafrost dynamics of WDML, Antarctica, are presented and discussed using data from six study sites, namely the Robertskollen, Vesleskarvet, Flarjuven, Grunehogna, Slettjfell nunataks and the Troll research station in the Jutulsessen area. Ground and ambient air temperature, as well as ground moisture data were collected for each site. An inventory of active layer and permafrost landforms was compiled, as were the frequency of cycles over the zero-degree isotherm, and the depth of the active layer. Furthermore, 3D models, geo-referenced maps and Digital Elevation Models were created of study areas with the use of an Unmanned Aerial Vehicle (UAV). Polygonal features are the most common landscape feature and are common to most of the study sites. Robertskollen has the deepest active layer at over 66cm and Slettfjell the shallowest at 9cm. A maximum recorded air temperature of 8.76°C (10/11/2014) occurred at Troll with the second highest maximum of 6.77°C (22/12/2010) recorded at Vesleskarvet. Robertskollen has the highest observable biological growth and a maximum recorded ground temperature of 22.84°C (10/01/2014). Troll and Valterkulten, registered the second and third highest ground temperatures respectively. The high ground Temperature observed for Robertskollen may be ascribed to it being the lowest altitude site. The highest number of cycles over the zero-degree isotherm was observed at Troll (11.01%), followed by Robertskollen (10.99%). For relatively warm areas, such as Robertskollen it is recommended that two metre borehole loggers are installed in order to capture a detailed understanding of the active layer. The UAV proved to be a beneficial tool for capturing aerial photographs for post fieldwork analysis and 3D modelling.
- Full Text:
Optical limiting and singlet oxygen generation properties of phosphorus triazatetrabenzcorroles
- Mkhize, Colin, Britton, Jonathan, Mack, John, Nyokong, Tebello
- Authors: Mkhize, Colin , Britton, Jonathan , Mack, John , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7257 , http://hdl.handle.net/10962/d1020266
- Description: Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole–pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. , Original publication is available at http://dx.doi.org/10.1142/S1088424614501065
- Full Text: false
- Authors: Mkhize, Colin , Britton, Jonathan , Mack, John , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7257 , http://hdl.handle.net/10962/d1020266
- Description: Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole–pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. , Original publication is available at http://dx.doi.org/10.1142/S1088424614501065
- Full Text: false
Optical properties of water-soluble L-cysteine-capped alloyed CdSeS quantum dot passivated with ZnSeTe and ZnSeTe/ZnS shells
- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B C
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193609 , vital:45352 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.024"
- Description: Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing L-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed L-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties.
- Full Text:
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193609 , vital:45352 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.024"
- Description: Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing L-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed L-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties.
- Full Text:
Optical properties of water-soluble l-cysteine-capped alloyed CdSeS quantum dot passivated with ZnSeTe and ZnSeTe/ZnS shells
- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B C
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7260 , http://hdl.handle.net/10962/d1020269
- Description: Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing l-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed l-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.024
- Full Text: false
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7260 , http://hdl.handle.net/10962/d1020269
- Description: Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing l-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed l-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.024
- Full Text: false
Optimisation of an electrochemical impedance spectroscopy aptasensor by exploiting quartz crystal microbalance with dissipation signals
- Formisanoa, Nello, Jolly, Pawan, Bhalla, Nikhil, Cromhout, Mary, Flanagan, Shane P, Fogel, Ronen, Limson, Janice L, Estrela, Pedro
- Authors: Formisanoa, Nello , Jolly, Pawan , Bhalla, Nikhil , Cromhout, Mary , Flanagan, Shane P , Fogel, Ronen , Limson, Janice L , Estrela, Pedro
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431699 , vital:72797 , xlink:href="https://doi.org/10.1016/j.snb.2015.05.049"
- Description: The response of an Electrochemical Impedance Spectroscopy (EIS) sensor using DNA aptamers is affected by many factors, such as DNA density, charge and conformational changes upon DNA-target binding, and buffer conditions. We report here for the first time on the optimisation of an EIS aptamer-based sensor by using Quartz Crystal Microbalance with Dissipation mode (QCM-D). As a case study, we employed a DNA aptamer against Prostate-Specific Antigen (PSA). PSA detection was achieved by functionalising the gold sensor surface via thiol chemistry with different ratios of thiolated-DNA aptamer and 6-mercapto-1-hexanol (MCH) used as spacer molecules. PSA binding efficiency can be monitored by measuring QCM-D signals which not only provide information about the mass of PSA bound on the sensor surface, but also crucial information about the aptamer conformation and layer hydration.
- Full Text:
- Authors: Formisanoa, Nello , Jolly, Pawan , Bhalla, Nikhil , Cromhout, Mary , Flanagan, Shane P , Fogel, Ronen , Limson, Janice L , Estrela, Pedro
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431699 , vital:72797 , xlink:href="https://doi.org/10.1016/j.snb.2015.05.049"
- Description: The response of an Electrochemical Impedance Spectroscopy (EIS) sensor using DNA aptamers is affected by many factors, such as DNA density, charge and conformational changes upon DNA-target binding, and buffer conditions. We report here for the first time on the optimisation of an EIS aptamer-based sensor by using Quartz Crystal Microbalance with Dissipation mode (QCM-D). As a case study, we employed a DNA aptamer against Prostate-Specific Antigen (PSA). PSA detection was achieved by functionalising the gold sensor surface via thiol chemistry with different ratios of thiolated-DNA aptamer and 6-mercapto-1-hexanol (MCH) used as spacer molecules. PSA binding efficiency can be monitored by measuring QCM-D signals which not only provide information about the mass of PSA bound on the sensor surface, but also crucial information about the aptamer conformation and layer hydration.
- Full Text:
Optimisation of the emulsion liquid membrane composition and demulsification for rhodium extraction
- Moyo, Francis, Tandlich, Roman
- Authors: Moyo, Francis , Tandlich, Roman
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76743 , vital:30626 , https://doi.org/10.1515/lwr-2015-0002
- Description: This study was aimed at designing an optimised emulsion liquid membrane (ELM) for the extraction of rhodium from precious metal refinery wastewaters. The demulsification process and the structure of the optimised ELM are reported on. Two optimised ELMs were prepared. The first one contained a 30 % solution of toluene in kerosene as diluent with the following concentrations of the ELM components: 30.000 g/L (w/v) polyisobutylene, 10.870 g/L (m/v) of trioctyl amine and 51.001 g/L (m/v) of SPAN 80. The second ELM contained the same diluent, but the concentrations of the other ELM components in it were as follows: 20.000 g/l of polyisobutylene, 10.268 g/l trioctyl amine and 50.024 g/l of SPAN 80. The stripping phase was the same in both optimised ELMs, namely a 2 M solution of HNO3. The stripping phase and the diluent solution were mixed together in ratios of 1:1 and 2:1, respectively. Two methods were used to characterise the microdroplet diameters, i.e. optical microscopy and the Zeta-sizer. For the t-test, the p-value of 0.3018 at 5 % level of significance showed that there was statistically no significant difference in the mean micro-droplet size for 1:2 ELMs containing 20 g/l and 30 g/l of polyisobutylene after 40 minutes of emulsification. The best demulsification results were obtained using the chemical demulsification with polyethylene glycol with molecular weight of 400 g/mol (PEG 400) at 50 ± 1 °C for 24 hours. However, significant carryover of toluene, trioctyl amine and polyethylene glycol into the aqueous phase was observed.
- Full Text:
- Authors: Moyo, Francis , Tandlich, Roman
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76743 , vital:30626 , https://doi.org/10.1515/lwr-2015-0002
- Description: This study was aimed at designing an optimised emulsion liquid membrane (ELM) for the extraction of rhodium from precious metal refinery wastewaters. The demulsification process and the structure of the optimised ELM are reported on. Two optimised ELMs were prepared. The first one contained a 30 % solution of toluene in kerosene as diluent with the following concentrations of the ELM components: 30.000 g/L (w/v) polyisobutylene, 10.870 g/L (m/v) of trioctyl amine and 51.001 g/L (m/v) of SPAN 80. The second ELM contained the same diluent, but the concentrations of the other ELM components in it were as follows: 20.000 g/l of polyisobutylene, 10.268 g/l trioctyl amine and 50.024 g/l of SPAN 80. The stripping phase was the same in both optimised ELMs, namely a 2 M solution of HNO3. The stripping phase and the diluent solution were mixed together in ratios of 1:1 and 2:1, respectively. Two methods were used to characterise the microdroplet diameters, i.e. optical microscopy and the Zeta-sizer. For the t-test, the p-value of 0.3018 at 5 % level of significance showed that there was statistically no significant difference in the mean micro-droplet size for 1:2 ELMs containing 20 g/l and 30 g/l of polyisobutylene after 40 minutes of emulsification. The best demulsification results were obtained using the chemical demulsification with polyethylene glycol with molecular weight of 400 g/mol (PEG 400) at 50 ± 1 °C for 24 hours. However, significant carryover of toluene, trioctyl amine and polyethylene glycol into the aqueous phase was observed.
- Full Text:
Organosilicon compounds as fluorescent chemosensors for fluoride anion recognition
- Gai, Lizhi, Mack, John, Lu, Hua, Nyokong, Tebello, Li, Zhifang, Kobayashi, Nagao, Shen, Zhen
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- Full Text:
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- Full Text:
Overexpression, Purification and Characterisation of the Plasmodium falciparum Hsp70-z (PfHsp70-z) Protein
- Zininga, Tawanda, Achilonu, Ikechukwu, Hoppe, Heinrich C, Prinsloo, Earl, Dirr, Heinrich W, Shonhai, Addmore
- Authors: Zininga, Tawanda , Achilonu, Ikechukwu , Hoppe, Heinrich C , Prinsloo, Earl , Dirr, Heinrich W , Shonhai, Addmore
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431719 , vital:72799 , xlink:href="https://doi.org/10.1371/journal.pone.0129445"
- Description: Six Hsp70-like genes are represented on the genome of Plasmodium falciparum. Of these two occur in the cytosol: P. falciparum Hsp70-z (PfHsp70-z) and PfHsp70-1. PfHsp70-1 is a well characterised canonical Hsp70 that facilitates protein quality control and is crucial for the development of malaria parasites. There is very little known about PfHsp70-z. However, PfHsp70-z is known to be essential and is implicated in suppressing aggregation of asparagine-rich proteins of P. falciparum. In addition, its expression at the clinical stage of malaria correlates with disease prognosis. Based on structural evidence PfHsp70-z belongs to the Hsp110 family of proteins. Since Hsp110 proteins have been described as nucleotide exchange factors (NEFs) of their canonical Hsp70 counterparts, it has been speculated that PfHsp70-z may serve as a NEF of PfHsp70-1. In the current study, P. falciparum cells cultured in vitro were subjected to heat stress, triggering the enhanced expression of PfHsp70-z. Biochemical assays conducted using recombinant PfHsp70-z protein demonstrated that the protein is heat stable and possesses ATPase activity. Furthermore, we observed that PfHsp70-z is capable of self-association. The structural-functional features of PfHsp70-z provide further evidence for its role as a chaperone and possible nucleotide exchange factor of PfHsp70-1.
- Full Text:
- Authors: Zininga, Tawanda , Achilonu, Ikechukwu , Hoppe, Heinrich C , Prinsloo, Earl , Dirr, Heinrich W , Shonhai, Addmore
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431719 , vital:72799 , xlink:href="https://doi.org/10.1371/journal.pone.0129445"
- Description: Six Hsp70-like genes are represented on the genome of Plasmodium falciparum. Of these two occur in the cytosol: P. falciparum Hsp70-z (PfHsp70-z) and PfHsp70-1. PfHsp70-1 is a well characterised canonical Hsp70 that facilitates protein quality control and is crucial for the development of malaria parasites. There is very little known about PfHsp70-z. However, PfHsp70-z is known to be essential and is implicated in suppressing aggregation of asparagine-rich proteins of P. falciparum. In addition, its expression at the clinical stage of malaria correlates with disease prognosis. Based on structural evidence PfHsp70-z belongs to the Hsp110 family of proteins. Since Hsp110 proteins have been described as nucleotide exchange factors (NEFs) of their canonical Hsp70 counterparts, it has been speculated that PfHsp70-z may serve as a NEF of PfHsp70-1. In the current study, P. falciparum cells cultured in vitro were subjected to heat stress, triggering the enhanced expression of PfHsp70-z. Biochemical assays conducted using recombinant PfHsp70-z protein demonstrated that the protein is heat stable and possesses ATPase activity. Furthermore, we observed that PfHsp70-z is capable of self-association. The structural-functional features of PfHsp70-z provide further evidence for its role as a chaperone and possible nucleotide exchange factor of PfHsp70-1.
- Full Text:
Oxford dictionary of journalism:
- Authors: Amner, Roderick J
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142656 , vital:38099 , DOI: 10.1080/23743670.2015.1041305
- Description: Tony Harcup is a self-confessed ‘hackademic’, a term which he defines in his Oxford dictionary of journalism as ‘a journalist who goes on to work in journalism education where they combine the roles of journalism (hack) and academic’ (p. 121). Harcup explains that hackademics perform this balancing act in the ‘hackademy’, a curious space within academe where journalism training intersects with Journalism Studies (a field of study which is nowadays often granted ‘upper case’ status), ‘sometimes with mutual respect and insight, sometimes with mutual suspicion and hostility’ (ibid.). And this tension is never far from the surface in many of the 1 300 definitions in this useful and absorbing dictionary.
- Full Text:
- Authors: Amner, Roderick J
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142656 , vital:38099 , DOI: 10.1080/23743670.2015.1041305
- Description: Tony Harcup is a self-confessed ‘hackademic’, a term which he defines in his Oxford dictionary of journalism as ‘a journalist who goes on to work in journalism education where they combine the roles of journalism (hack) and academic’ (p. 121). Harcup explains that hackademics perform this balancing act in the ‘hackademy’, a curious space within academe where journalism training intersects with Journalism Studies (a field of study which is nowadays often granted ‘upper case’ status), ‘sometimes with mutual respect and insight, sometimes with mutual suspicion and hostility’ (ibid.). And this tension is never far from the surface in many of the 1 300 definitions in this useful and absorbing dictionary.
- Full Text:
Parental involvement in school governance: a case study of a secondary school in Okahandja, Namibia
- Authors: Shikwambi, Victoria
- Date: 2015
- Subjects: Parent-teacher relationships -- Namibia -- Okahandja , Education -- Parent participation -- Namibia -- Okahandja , School management and organization -- Namibia -- Okahandja , School boards -- Namibia -- Okahandja
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2047 , http://hdl.handle.net/10962/d1017358
- Description: Since Namibia gained independence parents have increasingly been seen as equal partners in the education process. The Education Act 16 of 2001 provides for the democratic participation in schools by parents, learners and other education stakeholders through the introduction of regional Education Forums and School Boards in schools Parental involvement in school governance has been widely researched and has become a ‘hot topic’ worldwide, including in Namibia. This study investigated and described parental involvement through the School Board in school governance in a secondary school in Otjozondjupa region, Namibia. The study was conducted within a qualitative, interpretive paradigm. The study employed three data collection tools namely, semi-structured interviews, document analysis and observation. The School Board was made up of parents of different classes and backgrounds, i.e. employed, unemployed, professionals and business persons and with different levels of educational background. These members create a network that represents the voices of parents from different social groups, with different levels of social capital. The different levels of social capital shape the nature of the contributions and interactions on the Board. The study found that in spite of the frequency of interaction between the School Board, parents and the community the School Board is still in a dilemma as it is unable to connect with its prominent source of potential support, such as the business community, due to an outdated view that the school is well-off based on its historic status of privilege. With respect to communications with parents the focus tends to be on the negatives of learners’ behaviour or performance and the task of the parents in this regard. Broadening the agenda of the collaboration to include positive aspects of the child would add to the motivation of parents and open possibilities for new forms of collaboration. The school lacks a well-coordinated system for utilizing the available resources as well as community expertise for the benefit of the school. On the strength of the findings, one of the recommendations is for a more structured program and strategy for the Boards various interactions with the community and parents.
- Full Text:
- Authors: Shikwambi, Victoria
- Date: 2015
- Subjects: Parent-teacher relationships -- Namibia -- Okahandja , Education -- Parent participation -- Namibia -- Okahandja , School management and organization -- Namibia -- Okahandja , School boards -- Namibia -- Okahandja
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2047 , http://hdl.handle.net/10962/d1017358
- Description: Since Namibia gained independence parents have increasingly been seen as equal partners in the education process. The Education Act 16 of 2001 provides for the democratic participation in schools by parents, learners and other education stakeholders through the introduction of regional Education Forums and School Boards in schools Parental involvement in school governance has been widely researched and has become a ‘hot topic’ worldwide, including in Namibia. This study investigated and described parental involvement through the School Board in school governance in a secondary school in Otjozondjupa region, Namibia. The study was conducted within a qualitative, interpretive paradigm. The study employed three data collection tools namely, semi-structured interviews, document analysis and observation. The School Board was made up of parents of different classes and backgrounds, i.e. employed, unemployed, professionals and business persons and with different levels of educational background. These members create a network that represents the voices of parents from different social groups, with different levels of social capital. The different levels of social capital shape the nature of the contributions and interactions on the Board. The study found that in spite of the frequency of interaction between the School Board, parents and the community the School Board is still in a dilemma as it is unable to connect with its prominent source of potential support, such as the business community, due to an outdated view that the school is well-off based on its historic status of privilege. With respect to communications with parents the focus tends to be on the negatives of learners’ behaviour or performance and the task of the parents in this regard. Broadening the agenda of the collaboration to include positive aspects of the child would add to the motivation of parents and open possibilities for new forms of collaboration. The school lacks a well-coordinated system for utilizing the available resources as well as community expertise for the benefit of the school. On the strength of the findings, one of the recommendations is for a more structured program and strategy for the Boards various interactions with the community and parents.
- Full Text:
Pathologies of vision : representations of deviant women and the cyborg body
- Authors: Rheeder, Elle-Sandrah
- Date: 2015
- Subjects: Haraway, Donna Jeanne -- Criticism and interpretation , Deviant behavior in art , Cyborgs in art , Cyborgs in motion pictures , Women in art , Socialist feminism , Hysteria in literature , Hysteria -- History , Science fiction -- History and criticism , Visual communication in art
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2514 , http://hdl.handle.net/10962/d1020319
- Description: This thesis investigates the figure of the cyborg as conceptualised by Donna Haraway in The Cyborg Manifesto (1991). The figure of the cyborg, as a transgressive figure in the late twentieth century within socialist feminist discourse, is problematized with regard to its efficacy as a creature that challenges the constructed nature of gender and contests the boundary between human and machine through its ambiguous nature. Haraway’s notions of the cyborg, which she bases partly on cyborg characters from Science Fiction literature, deny the ocularcentric traditions that have structured gender and the body. Similarly, Haraway does not engage adequately with the figure of the cyborg with regard to situating it historically. This thesis unpacks both the visual and the historical aspects that have structured the cyborg body. By engaging with these concepts, the cyborg emerges as a figure that is identified through visual signifiers of female deviance and pathology. By reading female deviance and pathology on the body of the nineteenth-century hysteric, similarities can be drawn between the hysteric and the cyborg. Through a reading of Alien (1979); Blade Runner (1982); and Star Trek: First Contact (1996) key cyborg texts of the late twentieth century, the figure of the cyborg, and its relation to the deviant pathologised female can be understood when read against the body of the hysteric and how it was visually coded and communicated
- Full Text:
- Authors: Rheeder, Elle-Sandrah
- Date: 2015
- Subjects: Haraway, Donna Jeanne -- Criticism and interpretation , Deviant behavior in art , Cyborgs in art , Cyborgs in motion pictures , Women in art , Socialist feminism , Hysteria in literature , Hysteria -- History , Science fiction -- History and criticism , Visual communication in art
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2514 , http://hdl.handle.net/10962/d1020319
- Description: This thesis investigates the figure of the cyborg as conceptualised by Donna Haraway in The Cyborg Manifesto (1991). The figure of the cyborg, as a transgressive figure in the late twentieth century within socialist feminist discourse, is problematized with regard to its efficacy as a creature that challenges the constructed nature of gender and contests the boundary between human and machine through its ambiguous nature. Haraway’s notions of the cyborg, which she bases partly on cyborg characters from Science Fiction literature, deny the ocularcentric traditions that have structured gender and the body. Similarly, Haraway does not engage adequately with the figure of the cyborg with regard to situating it historically. This thesis unpacks both the visual and the historical aspects that have structured the cyborg body. By engaging with these concepts, the cyborg emerges as a figure that is identified through visual signifiers of female deviance and pathology. By reading female deviance and pathology on the body of the nineteenth-century hysteric, similarities can be drawn between the hysteric and the cyborg. Through a reading of Alien (1979); Blade Runner (1982); and Star Trek: First Contact (1996) key cyborg texts of the late twentieth century, the figure of the cyborg, and its relation to the deviant pathologised female can be understood when read against the body of the hysteric and how it was visually coded and communicated
- Full Text:
Patriarchy, women, land and livelihoods on A1 farms in Zimbabwe
- Chiweshe, Manase K, Chakona, Loveness, Helliker, Kirk D
- Authors: Chiweshe, Manase K , Chakona, Loveness , Helliker, Kirk D
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71204 , vital:29812 , https://doi.org/10.1177/0021909614541083
- Description: In this article, we focus on patriarchy, women, land and livelihoods on A1 farms in Zimbabwe which arose from the fast track land reform programme. There is now significant literature on A1 farms in Zimbabwe. These studies include a number of ethnographic and comparative studies but this literature does not give sustained attention to patriarchy and women. In addition, though, a small number of works have appeared based upon a more focused gender analysis. We draw upon this more focused literature and offer fresh fieldwork evidence based on recent studies undertaken by two of the authors, in Goromonzi and Mazowe districts. At times, radical socio-spatial reorganisation such as fast track may destabilise systems of patriarchy. In the case of fast track, there has been a reconfiguration of relations between men and women yet this is uneven and contradictory and remains within the confines of patriarchal structures, practices and discourses. At the same time, women have manoeuvred and negotiated at local levels to enhance their lives and livelihoods.
- Full Text: false
- Authors: Chiweshe, Manase K , Chakona, Loveness , Helliker, Kirk D
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71204 , vital:29812 , https://doi.org/10.1177/0021909614541083
- Description: In this article, we focus on patriarchy, women, land and livelihoods on A1 farms in Zimbabwe which arose from the fast track land reform programme. There is now significant literature on A1 farms in Zimbabwe. These studies include a number of ethnographic and comparative studies but this literature does not give sustained attention to patriarchy and women. In addition, though, a small number of works have appeared based upon a more focused gender analysis. We draw upon this more focused literature and offer fresh fieldwork evidence based on recent studies undertaken by two of the authors, in Goromonzi and Mazowe districts. At times, radical socio-spatial reorganisation such as fast track may destabilise systems of patriarchy. In the case of fast track, there has been a reconfiguration of relations between men and women yet this is uneven and contradictory and remains within the confines of patriarchal structures, practices and discourses. At the same time, women have manoeuvred and negotiated at local levels to enhance their lives and livelihoods.
- Full Text: false
Pecha Kucha 1: Critical Studies in Sexualities and Reproduction
- Authors: Macleod, Catriona I
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143915 , vital:38294 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Despite enabling legislation and policies in the areas of sexualities and reproduction in South Africa, multiple challenges persist, including: forced sexual debut, sexual coercion and violence; HIV infection; hate crimes against lesbian women and gay men; unwanted and unsupportable pregnancies. While it is acknowledged that interventions (e.g., sexuality education programmes, the promotion of antenatal care use and the promotion of non-discrimination) have the potential to improve men’s and women’s sexual and reproductive lives. There are also multiple ways in which such programmes and the surrounding public discourses concerning sexuality and reproduction can serve in often unintended and unwitting ways to perpetuate oppressive heteronormative, gendered, racialised and class-based power relations. The Critical Studies in Sexualities and Reproduction research programme focuses on how particular discourses, narratives, and practices promote inclusion or exclusion, belonging or marginalisation, equity or inequity, justice or injustice, access to, or denial of, sexual and reproductive rights.
- Full Text:
- Authors: Macleod, Catriona I
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143915 , vital:38294 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Despite enabling legislation and policies in the areas of sexualities and reproduction in South Africa, multiple challenges persist, including: forced sexual debut, sexual coercion and violence; HIV infection; hate crimes against lesbian women and gay men; unwanted and unsupportable pregnancies. While it is acknowledged that interventions (e.g., sexuality education programmes, the promotion of antenatal care use and the promotion of non-discrimination) have the potential to improve men’s and women’s sexual and reproductive lives. There are also multiple ways in which such programmes and the surrounding public discourses concerning sexuality and reproduction can serve in often unintended and unwitting ways to perpetuate oppressive heteronormative, gendered, racialised and class-based power relations. The Critical Studies in Sexualities and Reproduction research programme focuses on how particular discourses, narratives, and practices promote inclusion or exclusion, belonging or marginalisation, equity or inequity, justice or injustice, access to, or denial of, sexual and reproductive rights.
- Full Text:
Pecha Kucha 2: Race and gender politics in cross-dressing, dressing-up, and drag
- Authors: Marx, Jacqueline
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143926 , vital:38295 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Sexuality is often less discernible than other markers of identity such as race and gender, which means that its perceptibility is often contingent on strategies that make it visible. Visibility is an especially important dimension in the shaping of lesbian and gay identities because people are generally assumed to be heterosexual. Making gay and lesbian identities visible is also an important political issue for people who have, historically, been threatened by the violence of public erasure. It is this aspect of gay and lesbian subjectivity – the politics of visibility – that is the topic of this presentation. We focus on gender and race politics in dressing-up, cross-dressing and drag performances - practices which make gay and lesbian sexualities visible, and consider the role that race and gender play in diminishing and exacerbating visibility.
- Full Text:
- Authors: Marx, Jacqueline
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143926 , vital:38295 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Sexuality is often less discernible than other markers of identity such as race and gender, which means that its perceptibility is often contingent on strategies that make it visible. Visibility is an especially important dimension in the shaping of lesbian and gay identities because people are generally assumed to be heterosexual. Making gay and lesbian identities visible is also an important political issue for people who have, historically, been threatened by the violence of public erasure. It is this aspect of gay and lesbian subjectivity – the politics of visibility – that is the topic of this presentation. We focus on gender and race politics in dressing-up, cross-dressing and drag performances - practices which make gay and lesbian sexualities visible, and consider the role that race and gender play in diminishing and exacerbating visibility.
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