Meso-and axially-modified IrIIItriarylcorroles with tunable electrocatalytic properties
- Zhang, Xifeng, Wang, Yu, Zhu, Weihua, Mack, John, Soy, Rodah C, Nyokong, Tebello, Liang, Xu
- Authors: Zhang, Xifeng , Wang, Yu , Zhu, Weihua , Mack, John , Soy, Rodah C , Nyokong, Tebello , Liang, Xu
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190851 , vital:45034 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: The synthesis of three A2B type Ir(III)triarylcorroles with meso-aryl substituents that provide electron donating (push) and withdrawing (pull) properties and three A3 type IrIIItriphenylcorroles with differing pyridine axial ligands is reported, along with their structural characterization. An analysis of the structure-property relationships in the optical and redox properties has been carried out by comparing their optical spectroscopy and electrochemistry to trends predicted in DFT and TD-DFT calculations. The results demonstrate that A2B type IrIIItriarylcorroles are highly efficient electrocatalyzed oxygen reduction reactions (ORRs) and that their reactivity can be modulated by modulating the electronic structure by changing the nature of the meso-substituent at the B-positions, and even axial pyridine ligands.
- Full Text:
- Date Issued: 2015
- Authors: Zhang, Xifeng , Wang, Yu , Zhu, Weihua , Mack, John , Soy, Rodah C , Nyokong, Tebello , Liang, Xu
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190851 , vital:45034 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: The synthesis of three A2B type Ir(III)triarylcorroles with meso-aryl substituents that provide electron donating (push) and withdrawing (pull) properties and three A3 type IrIIItriphenylcorroles with differing pyridine axial ligands is reported, along with their structural characterization. An analysis of the structure-property relationships in the optical and redox properties has been carried out by comparing their optical spectroscopy and electrochemistry to trends predicted in DFT and TD-DFT calculations. The results demonstrate that A2B type IrIIItriarylcorroles are highly efficient electrocatalyzed oxygen reduction reactions (ORRs) and that their reactivity can be modulated by modulating the electronic structure by changing the nature of the meso-substituent at the B-positions, and even axial pyridine ligands.
- Full Text:
- Date Issued: 2015
Microbial water quality of treated water and raw water sources in the Harare area, Zimbabwe
- Chirenda, Tatenda G, Srinivas, Sunitha C, Tandlich, Roman
- Authors: Chirenda, Tatenda G , Srinivas, Sunitha C , Tandlich, Roman
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76206 , vital:30520 , http://dx.doi.org/10.4314/wsa.v41i5.12
- Description: Microbial water quality is an essential aspect in the provision of potable water for domestic use. The provision of adequate amounts of safe water for domestic purposes has become difficult for most municipalities mandated to do so in Zimbabwe. Morton-Jaffray Treatment Plant supplies potable water to Harare City and areas surrounding Harare. This study investigated microbial water quality and the impact of microbial water quality related disasters in the area supplied by the Morton Jaffray Treatment Plant. Questionnaires were distributed to household owners in Harare who receive their water from the Municipality and those who use alternate water supplies. Candidates were randomly selected from their workplace. The raw water quality of Manyame River and its tributaries was assessed. Treated water in households was assessed for microbial quality using hydrogen sulphide test and heterotrophic bacteria plate count. Raw water sources were found to be contaminated by faecal matter. Household water sources tested negative for faecal contamination but positive for heterotrophic bacteria. CFU quantities ranged from 1 to 452 CFU/m. for all samples. The WHO guidelines for domestic water sources state that water used for domestic purposes should not be contain than 100 CFU/m.. Public perceptions of water quality ranged from eunsafef to ehighly contaminatedf. A decrease in the level of aesthetic appeal resulted in residents resorting to alternative sources such as wells and rivers for their domestic water. The current state of treated water was suitable for domestic use. Pathogen monitoring of domestic water is recommended using the hydrogen sulphide test and R2A agar test.
- Full Text:
- Date Issued: 2015
- Authors: Chirenda, Tatenda G , Srinivas, Sunitha C , Tandlich, Roman
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76206 , vital:30520 , http://dx.doi.org/10.4314/wsa.v41i5.12
- Description: Microbial water quality is an essential aspect in the provision of potable water for domestic use. The provision of adequate amounts of safe water for domestic purposes has become difficult for most municipalities mandated to do so in Zimbabwe. Morton-Jaffray Treatment Plant supplies potable water to Harare City and areas surrounding Harare. This study investigated microbial water quality and the impact of microbial water quality related disasters in the area supplied by the Morton Jaffray Treatment Plant. Questionnaires were distributed to household owners in Harare who receive their water from the Municipality and those who use alternate water supplies. Candidates were randomly selected from their workplace. The raw water quality of Manyame River and its tributaries was assessed. Treated water in households was assessed for microbial quality using hydrogen sulphide test and heterotrophic bacteria plate count. Raw water sources were found to be contaminated by faecal matter. Household water sources tested negative for faecal contamination but positive for heterotrophic bacteria. CFU quantities ranged from 1 to 452 CFU/m. for all samples. The WHO guidelines for domestic water sources state that water used for domestic purposes should not be contain than 100 CFU/m.. Public perceptions of water quality ranged from eunsafef to ehighly contaminatedf. A decrease in the level of aesthetic appeal resulted in residents resorting to alternative sources such as wells and rivers for their domestic water. The current state of treated water was suitable for domestic use. Pathogen monitoring of domestic water is recommended using the hydrogen sulphide test and R2A agar test.
- Full Text:
- Date Issued: 2015
Modelling stock return volatility dynamics in selected African markets
- Authors: King, Daniel , Botha, Ferdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396104 , vital:69150 , xlink:href=" https://doi.org/10.1016/j.econmod.2014.11.008"
- Description: This paper examines whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002–2012. In the univariate portion of the paper, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. Accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important in capturing heteroscedasticity. However, those univariate models including a GARCH term perform comparatively poorly when used for forecasting purposes. In the multivariate study, the use of Markov-switching variance–covariance estimates improves risk-adjusted portfolio returns relative to portfolios constructed using the more conventional single-state models. While there is evidence that some Markov-switching models can provide better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture heteroscedasticity in the data remains problematic.
- Full Text:
- Date Issued: 2015
- Authors: King, Daniel , Botha, Ferdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396104 , vital:69150 , xlink:href=" https://doi.org/10.1016/j.econmod.2014.11.008"
- Description: This paper examines whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002–2012. In the univariate portion of the paper, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. Accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important in capturing heteroscedasticity. However, those univariate models including a GARCH term perform comparatively poorly when used for forecasting purposes. In the multivariate study, the use of Markov-switching variance–covariance estimates improves risk-adjusted portfolio returns relative to portfolios constructed using the more conventional single-state models. While there is evidence that some Markov-switching models can provide better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture heteroscedasticity in the data remains problematic.
- Full Text:
- Date Issued: 2015
Modification and application of the decentralised wastewater treatment technology for greywater treatment to reduce water needs
- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2015
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193509 , vital:45338
- Description: Water is a scarce resource that is being acknowledged as a limiting factor to further social- economic growth and development. Demand for freshwater is increasing with corresponding increases in human population, industrial and agricultural activities. Alternative sources, such as greywater and rainwater are often polluted. Though greywater can be used for non-potable purposes, such as irrigation, it still requires some measures of treatment to improve its quality. To improve on greywater quality to facilitate its reuse, decentralised wastewater treatment technologies carry a great potential as complementary and alternative means of wastewater management particularly in peri-urban areas. Five research goals are addressed in this thesis: (i) to monitor the performance of Fly Ash Lime Filter Tower (FLFT) in the treatment of greywater; (ii) to modify the Fly Ash Lime Filter Tower in the treatment of greywater in order to reduce the pH of the greywater, and improved on the reduction of chemical oxygen demand (COD) and coliform counts; (iii) to investigate the potential of the reuse of greywater for irrigation; (iv) to undertake a techno analysis of the FLFT system for commercial use; and (v) to evaluate the use of hydrogen-sulphide (H2S) test kit to monitor faecal contamination of various water sources using a multidisciplinary approach. The modification of the FLFT indicated good treatment efficiency, reducing the concentrations of COD, chlorides, nitrates, ammonia and sulphate by 82.6%, 60.4%, 72.9%, 60.5%, and 53.9%, respectively; while the average pH was at 8.3. Greywater contains nutrients that are beneficial to the growth of most plants. Growth variables included biomass, stem height, number of leaves and number of vegetables harvested. Soil analysis showed no effects of the treated greywater on soil physico-chemical and microbial quality with bulk density 2.0g/cm3, average pH 7.4, total phosphorus 0.16mg/L 8, faecal coliform 0.3 CFU/100 ml. The tomatoes had high biomass and dry weight (150 g; 33g) than beetroot (35 g; 15 g). Crops irrigated with greywater significantly grew faster compared with those irrigated with tap water. The community approach highlighted the value of knowledge management in greywater reuse. It highlighted the importance of creating an institutional knowledge in water management using the H2S kit. The techno-economic analysis was used to evaluate key factors and the activities that are relevant to develop a sustainable FLFT in order to gain insights into the possibility of developing, and incorporating a business model framework to support decision making in value creation and value capturing during the research and the scaling up of the system. By this, a long term perspective to accomplish sustainable FLFT service businesses can be achieved. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2015
- Full Text:
- Date Issued: 2015
- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2015
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193509 , vital:45338
- Description: Water is a scarce resource that is being acknowledged as a limiting factor to further social- economic growth and development. Demand for freshwater is increasing with corresponding increases in human population, industrial and agricultural activities. Alternative sources, such as greywater and rainwater are often polluted. Though greywater can be used for non-potable purposes, such as irrigation, it still requires some measures of treatment to improve its quality. To improve on greywater quality to facilitate its reuse, decentralised wastewater treatment technologies carry a great potential as complementary and alternative means of wastewater management particularly in peri-urban areas. Five research goals are addressed in this thesis: (i) to monitor the performance of Fly Ash Lime Filter Tower (FLFT) in the treatment of greywater; (ii) to modify the Fly Ash Lime Filter Tower in the treatment of greywater in order to reduce the pH of the greywater, and improved on the reduction of chemical oxygen demand (COD) and coliform counts; (iii) to investigate the potential of the reuse of greywater for irrigation; (iv) to undertake a techno analysis of the FLFT system for commercial use; and (v) to evaluate the use of hydrogen-sulphide (H2S) test kit to monitor faecal contamination of various water sources using a multidisciplinary approach. The modification of the FLFT indicated good treatment efficiency, reducing the concentrations of COD, chlorides, nitrates, ammonia and sulphate by 82.6%, 60.4%, 72.9%, 60.5%, and 53.9%, respectively; while the average pH was at 8.3. Greywater contains nutrients that are beneficial to the growth of most plants. Growth variables included biomass, stem height, number of leaves and number of vegetables harvested. Soil analysis showed no effects of the treated greywater on soil physico-chemical and microbial quality with bulk density 2.0g/cm3, average pH 7.4, total phosphorus 0.16mg/L 8, faecal coliform 0.3 CFU/100 ml. The tomatoes had high biomass and dry weight (150 g; 33g) than beetroot (35 g; 15 g). Crops irrigated with greywater significantly grew faster compared with those irrigated with tap water. The community approach highlighted the value of knowledge management in greywater reuse. It highlighted the importance of creating an institutional knowledge in water management using the H2S kit. The techno-economic analysis was used to evaluate key factors and the activities that are relevant to develop a sustainable FLFT in order to gain insights into the possibility of developing, and incorporating a business model framework to support decision making in value creation and value capturing during the research and the scaling up of the system. By this, a long term perspective to accomplish sustainable FLFT service businesses can be achieved. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2015
- Full Text:
- Date Issued: 2015
Multiple benefits and values of trees in urban landscapes in two towns in northern South Africa
- Shackleton, Sheona E, Chinyimba, Abby, Hebinck, Paul, Shackleton, Charlie M, Kaoma, Humphrey
- Authors: Shackleton, Sheona E , Chinyimba, Abby , Hebinck, Paul , Shackleton, Charlie M , Kaoma, Humphrey
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180874 , vital:43658 , xlink:href="https://doi.org/10.1016/j.landurbplan.2014.12.004"
- Description: Cities and towns can be conceptualised as complex social-ecological systems or landscapes that are composed of different spatial elements. Trees in urban landscapes provide a variety of tangible and intangible benefits (ecosystem services) that may be valued differently across diverse households and individuals. Here, we consider how the benefits and values of trees to urban residents vary across public and private spaces in three low income neighbourhoods in two medium-sized towns in northern South Africa. We find that the most asset poor residents in informal settlements derive significant benefits from the provisioning services offered by trees in natural green spaces on the ‘urban periphery’; in particular they value supplies of wood for energy, whilst also recognising the importance of regulating services such as shade. Trees in such spaces help these immigrants cope with a lack of infrastructure, services and disposable income after their move to the city. In new, low-cost housing neighbourhoods, the importance of trees in providing shade and shelter in gardens is emphasised due to the hot and dusty nature of these settlements, while residents in older township neighbourhoods make more mention of the aesthetic value of trees in private spaces as well as the fruits they provide. In all neighbourhoods, attitudes towards trees in public spaces were mixed because of their perceived association with crime, although low income households did make extensive use of tree products from natural areas. The relevance of the results for urban planning and greening in low income areas is discussed.
- Full Text:
- Date Issued: 2015
- Authors: Shackleton, Sheona E , Chinyimba, Abby , Hebinck, Paul , Shackleton, Charlie M , Kaoma, Humphrey
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180874 , vital:43658 , xlink:href="https://doi.org/10.1016/j.landurbplan.2014.12.004"
- Description: Cities and towns can be conceptualised as complex social-ecological systems or landscapes that are composed of different spatial elements. Trees in urban landscapes provide a variety of tangible and intangible benefits (ecosystem services) that may be valued differently across diverse households and individuals. Here, we consider how the benefits and values of trees to urban residents vary across public and private spaces in three low income neighbourhoods in two medium-sized towns in northern South Africa. We find that the most asset poor residents in informal settlements derive significant benefits from the provisioning services offered by trees in natural green spaces on the ‘urban periphery’; in particular they value supplies of wood for energy, whilst also recognising the importance of regulating services such as shade. Trees in such spaces help these immigrants cope with a lack of infrastructure, services and disposable income after their move to the city. In new, low-cost housing neighbourhoods, the importance of trees in providing shade and shelter in gardens is emphasised due to the hot and dusty nature of these settlements, while residents in older township neighbourhoods make more mention of the aesthetic value of trees in private spaces as well as the fruits they provide. In all neighbourhoods, attitudes towards trees in public spaces were mixed because of their perceived association with crime, although low income households did make extensive use of tree products from natural areas. The relevance of the results for urban planning and greening in low income areas is discussed.
- Full Text:
- Date Issued: 2015
Multiple femininities in a'single sex'school: re-orienting Life Orientation to learner lifeworlds
- Mthatyana, Andisiwe, Vincent, Louise
- Authors: Mthatyana, Andisiwe , Vincent, Louise
- Date: 2015
- Language: English
- Type: text , article
- Identifier: vital:38019 , http://hdl.handle.net/11660/3689
- Description: Life Orientation sexuality education in South Africa faces many pedagogical challenges, not least among which is that it is sometimes perceived as irrelevant to learners' real interests and concerns. Learners report that the content is repetitive and that they learn more from peers than from the reiterated lessons of risk and disease avoidance that permeate sex education messages. In this article we describe the world of the study site - a 'single sex' school - as consisting of diverse informal student sexual cultures in which repertoires for the development of learner sexual identities are developed, negotiated and transmitted. The study is based on detailed ethnographic immersion in the study site which generated rich data drawn from in-depth interviews, focus groups, observations and solicited narratives. We argue that even the enlightened, tolerant 'best practice' form of sexuality education that takes place at the study site fails to take diverse learner identities, lifeworlds and experiences seriously as a pedagogic starting point, but rather tends to homogenise learners and to impose on them what they need to learn. A more empowering form of sexuality education would take seriously how young people understand themselves as sexual subjects located in unequal ('raced' and classed) social contexts.
- Full Text:
- Date Issued: 2015
- Authors: Mthatyana, Andisiwe , Vincent, Louise
- Date: 2015
- Language: English
- Type: text , article
- Identifier: vital:38019 , http://hdl.handle.net/11660/3689
- Description: Life Orientation sexuality education in South Africa faces many pedagogical challenges, not least among which is that it is sometimes perceived as irrelevant to learners' real interests and concerns. Learners report that the content is repetitive and that they learn more from peers than from the reiterated lessons of risk and disease avoidance that permeate sex education messages. In this article we describe the world of the study site - a 'single sex' school - as consisting of diverse informal student sexual cultures in which repertoires for the development of learner sexual identities are developed, negotiated and transmitted. The study is based on detailed ethnographic immersion in the study site which generated rich data drawn from in-depth interviews, focus groups, observations and solicited narratives. We argue that even the enlightened, tolerant 'best practice' form of sexuality education that takes place at the study site fails to take diverse learner identities, lifeworlds and experiences seriously as a pedagogic starting point, but rather tends to homogenise learners and to impose on them what they need to learn. A more empowering form of sexuality education would take seriously how young people understand themselves as sexual subjects located in unequal ('raced' and classed) social contexts.
- Full Text:
- Date Issued: 2015
Nanosecond nonlinear optical limiting properties of new trinuclear lanthanide phthalocyanines in solution and as thin films
- Sekhosana, Kutloana E, Amuhaya, Edith, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Amuhaya, Edith , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189752 , vital:44928 , xlink:href="https://doi.org/10.1016/j.poly.2014.08.047"
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions.
- Full Text:
- Date Issued: 2015
- Authors: Sekhosana, Kutloana E , Amuhaya, Edith , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189752 , vital:44928 , xlink:href="https://doi.org/10.1016/j.poly.2014.08.047"
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions.
- Full Text:
- Date Issued: 2015
New school meets old school: journalism education in Africa’s newest country
- Authors: du Toit, Peter
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158691 , vital:40221 , https://hdl.handle.net/10520/EJC175767
- Description: South Sudanese journalists have a critical contribution to make in promoting peace, development and democracy in Africa's newest state, but many lack the training and skills to fulfill this potential.
- Full Text:
- Date Issued: 2015
- Authors: du Toit, Peter
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158691 , vital:40221 , https://hdl.handle.net/10520/EJC175767
- Description: South Sudanese journalists have a critical contribution to make in promoting peace, development and democracy in Africa's newest state, but many lack the training and skills to fulfill this potential.
- Full Text:
- Date Issued: 2015
NGOization: Complicity, Contradictions and Prospects
- Authors: Helliker, Kirk D
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144699 , vital:38371 , DOI: 10.1177/0021909614535552
- Description: This book focuses on the process of ‘NGOization’, namely, ‘the institutionalization, professionalization, depoliticization and demobilization of movements’ for social change (p. 1) by non-governmental organizations (NGOs). This process arises in and through the interface and relations between movements and NGOs and it highlights the overall system-maintenance role of NGOs. Of course, NGOs may not deliberately seek to depoliticize and demobilize movements. Rather, NGOization may involve the unintended consequences of the logic and dispositions of NGOs as a particular organization form.
- Full Text:
- Date Issued: 2015
- Authors: Helliker, Kirk D
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144699 , vital:38371 , DOI: 10.1177/0021909614535552
- Description: This book focuses on the process of ‘NGOization’, namely, ‘the institutionalization, professionalization, depoliticization and demobilization of movements’ for social change (p. 1) by non-governmental organizations (NGOs). This process arises in and through the interface and relations between movements and NGOs and it highlights the overall system-maintenance role of NGOs. Of course, NGOs may not deliberately seek to depoliticize and demobilize movements. Rather, NGOization may involve the unintended consequences of the logic and dispositions of NGOs as a particular organization form.
- Full Text:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
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:
- Date Issued: 2015
- 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:
- Date Issued: 2015
Pecha Kucha 3: Memories, photographs, and archives: On historicising ‘puberty’ in the present
- Authors: Pinto, Pedro
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143937 , vital:38296 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: In 1997, Valerie Walkerdine incited researchers to use memory and fantasy as devices to explore the gendered meanings of being a child and becoming adult. Since we all once were children, we are in the ambiguous – and therefore productive – position of being both informants and ethnographers of childhood experiences. Whilst drawing on a historical investigation on puberty science, this presentation is a hybrid experiment: it combines my memories of growing up in Portugal in the early 1980s and photographs of children taken in clinical interventions from the late nineteenth century to the first decades of the twentieth. In articulating these materials and their different temporalities, my purpose is to explore the techniques and the power relations in which pubertal development came to being thought of, and disciplined, in contemporary societies. In doing so, I invite the possibility of historicising experience as a strategy to critically analyse our medicalised present.
- Full Text:
- Date Issued: 2015
- Authors: Pinto, Pedro
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143937 , vital:38296 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: In 1997, Valerie Walkerdine incited researchers to use memory and fantasy as devices to explore the gendered meanings of being a child and becoming adult. Since we all once were children, we are in the ambiguous – and therefore productive – position of being both informants and ethnographers of childhood experiences. Whilst drawing on a historical investigation on puberty science, this presentation is a hybrid experiment: it combines my memories of growing up in Portugal in the early 1980s and photographs of children taken in clinical interventions from the late nineteenth century to the first decades of the twentieth. In articulating these materials and their different temporalities, my purpose is to explore the techniques and the power relations in which pubertal development came to being thought of, and disciplined, in contemporary societies. In doing so, I invite the possibility of historicising experience as a strategy to critically analyse our medicalised present.
- Full Text:
- Date Issued: 2015
Perceptions of the natural environment from a rural African perspective: a case of Cylondropuntia fulgida var. fulgida in Gwanda district, Zimbabwe
- Dube, Nqobizitha, Snowball, Jeanette D, Fraser, Gavin C G
- Authors: Dube, Nqobizitha , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68578 , vital:29289 , http://2015.essa.org.za/fullpaper/essa_2994.pdf
- Description: Publisher version , Community environmental perceptions are instrumental in environmental management programmes given that perspectives govern human-environment relations. Despite numerous studies on environmental perceptions, little is known about how the rural poor particularly in Africa conceptualize, live with, and respond to pressing environmental issues facing them. As such, this paper uses the case of an invasive alien plant (IAP) (Cylindropuntia fulgida var. fulgida (Cff)) in a rural community (Gwanda district, Zimbabwe) to unveil the conceptualisation of the natural environment from a rural African perspective. This paper discloses the environmental worldview of the community and explains the formulation of the attitudes by the local households towards species in the environment. The study uses two horizontal dimensions of environmental attitudes formulation (New Environmental Paradigm (NEP) Scale and Kellet’s (1996) classification of environmental values). Data was collected using a questionnaire survey, group discussions and key informant interviews. A sample of 156 individuals comprised the study respondents. Results showed the residents of rural Gwanda district to hold both a conservation and utilisation conviction (syncretic view) towards the environment. However, utilisation outweighs conservation. Furthermore, older residents are more inclined to conservation in comparison to the youth. The study also divulged that the origin of a species in the natural environment was insignificant to the host community. However, the livelihood effects that species had (regardless of origins) were the major determinants of attitudes developed towards it.
- Full Text:
- Date Issued: 2015
- Authors: Dube, Nqobizitha , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68578 , vital:29289 , http://2015.essa.org.za/fullpaper/essa_2994.pdf
- Description: Publisher version , Community environmental perceptions are instrumental in environmental management programmes given that perspectives govern human-environment relations. Despite numerous studies on environmental perceptions, little is known about how the rural poor particularly in Africa conceptualize, live with, and respond to pressing environmental issues facing them. As such, this paper uses the case of an invasive alien plant (IAP) (Cylindropuntia fulgida var. fulgida (Cff)) in a rural community (Gwanda district, Zimbabwe) to unveil the conceptualisation of the natural environment from a rural African perspective. This paper discloses the environmental worldview of the community and explains the formulation of the attitudes by the local households towards species in the environment. The study uses two horizontal dimensions of environmental attitudes formulation (New Environmental Paradigm (NEP) Scale and Kellet’s (1996) classification of environmental values). Data was collected using a questionnaire survey, group discussions and key informant interviews. A sample of 156 individuals comprised the study respondents. Results showed the residents of rural Gwanda district to hold both a conservation and utilisation conviction (syncretic view) towards the environment. However, utilisation outweighs conservation. Furthermore, older residents are more inclined to conservation in comparison to the youth. The study also divulged that the origin of a species in the natural environment was insignificant to the host community. However, the livelihood effects that species had (regardless of origins) were the major determinants of attitudes developed towards it.
- Full Text:
- Date Issued: 2015
Photocatalytic behaviour of zinc tetraamino phthalocyanine-silver nanoparticles immobilized on chitosan beads
- Khoza, Phindile, Nyokong, Tebello
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189468 , vital:44849 , xlink:href="https://doi.org/10.1016/j.molcata.2015.01.017"
- Description: Photocatalytic degradation of Rhodamine 6G using unconjugated zinc tetraamino phthalocyanine (ZnTAPc) or when conjugated to Ag nanoparticles (ZnTAPc–AgNPs) is reported. Upon conjugating ZnTAPc to silver nanoparticles, the singlet oxygen production of the phthalocyanine was slightly increased. ZnTAPc and ZnTAPc–AgNPs were immobilized onto chitosan beads for ease of recovery after photocatalysis. Chitosan beads were characterized by FTIR, XRD and TGA. The photodegradation of Rhodamine 6G was used to evaluate the efficiency of the immobilized photocatalysts. In the presence of AgNPs, the photodegradation of Rhodamine 6G was enhanced. The apparent rates (k) were found to be 8.51 × 10−8 and 1.61 × 10−7 mol L−1 min−1 for chitosan supported ZnTAPc or ZnTAPc–AgNPs, respectively. The observation of good photocatalytic activity of the ZnTAPc when immobilized on chitosan proves the uncompromised efficiency of the photocatalysts even when confined in beads, showing great potential for the functionalized beads as heterogeneous catalysts.
- Full Text:
- Date Issued: 2015
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189468 , vital:44849 , xlink:href="https://doi.org/10.1016/j.molcata.2015.01.017"
- Description: Photocatalytic degradation of Rhodamine 6G using unconjugated zinc tetraamino phthalocyanine (ZnTAPc) or when conjugated to Ag nanoparticles (ZnTAPc–AgNPs) is reported. Upon conjugating ZnTAPc to silver nanoparticles, the singlet oxygen production of the phthalocyanine was slightly increased. ZnTAPc and ZnTAPc–AgNPs were immobilized onto chitosan beads for ease of recovery after photocatalysis. Chitosan beads were characterized by FTIR, XRD and TGA. The photodegradation of Rhodamine 6G was used to evaluate the efficiency of the immobilized photocatalysts. In the presence of AgNPs, the photodegradation of Rhodamine 6G was enhanced. The apparent rates (k) were found to be 8.51 × 10−8 and 1.61 × 10−7 mol L−1 min−1 for chitosan supported ZnTAPc or ZnTAPc–AgNPs, respectively. The observation of good photocatalytic activity of the ZnTAPc when immobilized on chitosan proves the uncompromised efficiency of the photocatalysts even when confined in beads, showing great potential for the functionalized beads as heterogeneous catalysts.
- Full Text:
- Date Issued: 2015
Photodynamic antimicrobial chemotherapy activity of (5, 10, 15, 20-tetrakis (4-(4-carboxyphenycarbonoimidoyl) phenyl) porphyrinato) chloro gallium (III)
- Managa, Muthumuni, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Managa, Muthumuni , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189043 , vital:44811 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.088"
- Description: (5,10,15,20-Tetrakis(4-(4-carboxyphenycarbonoimidoyl)phenyl)porphyrinato) chloro gallium(III) (complex 1) was conjugated to platinum nanoparticles (PtNPs) (represented as 1-PtNPs). The resulting conjugate showed 18 nm red shift in the Soret band when compared to 1 alone. Complex 1 and 1-PtNPs showed promising photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus, Escherichia coli and Candida albicans in solution where the log reductions obtained were 4.92, 3.76, and 3.95, respectively for 1-PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 1-PtNPs in DMF while that of 1 was 0.52 in the same solvent. This resulted in improved PACT activity for 1-PtNPs compared to 1 alone.
- Full Text:
- Date Issued: 2015
- Authors: Managa, Muthumuni , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189043 , vital:44811 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.088"
- Description: (5,10,15,20-Tetrakis(4-(4-carboxyphenycarbonoimidoyl)phenyl)porphyrinato) chloro gallium(III) (complex 1) was conjugated to platinum nanoparticles (PtNPs) (represented as 1-PtNPs). The resulting conjugate showed 18 nm red shift in the Soret band when compared to 1 alone. Complex 1 and 1-PtNPs showed promising photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus, Escherichia coli and Candida albicans in solution where the log reductions obtained were 4.92, 3.76, and 3.95, respectively for 1-PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 1-PtNPs in DMF while that of 1 was 0.52 in the same solvent. This resulted in improved PACT activity for 1-PtNPs compared to 1 alone.
- Full Text:
- Date Issued: 2015