A kernel-driven framework for high performance internet routing simulation
- Herbert, Alan, Irwin, Barry V W
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429585 , vital:72624 , 10.1109/ISSA.2013.6641048
- Description: The ability to provide the simulation of packets traversing an internet path is an integral part of providing realistic simulations for network training, and cyber defence exercises. This paper builds on previous work, and considers an in-kernel approach to solving the routing simulation problem. The inkernel approach is anticipated to allow the framework to be able to achieve throughput rates of 1GB/s or higher using commodity hardware. Processes that run outside the context of the kernel of most operating system require context switching to access hardware and kernel modules. This leads to considerable delays in the processes, such as network simulators, that frequently access hardware such as hard disk accesses and network packet handling. To mitigate this problem, as experienced with earlier implementations, this research looks towards implementing a kernel module to handle network routing and simulation within a UNIX based system. This would remove delays incurred from context switching and allows for direct access to the hardware components of the host.
- Full Text:
- Date Issued: 2013
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429585 , vital:72624 , 10.1109/ISSA.2013.6641048
- Description: The ability to provide the simulation of packets traversing an internet path is an integral part of providing realistic simulations for network training, and cyber defence exercises. This paper builds on previous work, and considers an in-kernel approach to solving the routing simulation problem. The inkernel approach is anticipated to allow the framework to be able to achieve throughput rates of 1GB/s or higher using commodity hardware. Processes that run outside the context of the kernel of most operating system require context switching to access hardware and kernel modules. This leads to considerable delays in the processes, such as network simulators, that frequently access hardware such as hard disk accesses and network packet handling. To mitigate this problem, as experienced with earlier implementations, this research looks towards implementing a kernel module to handle network routing and simulation within a UNIX based system. This would remove delays incurred from context switching and allows for direct access to the hardware components of the host.
- Full Text:
- Date Issued: 2013
A maturing manifesto: the constitutionalisation of children’s rights in South African jurisprudence 2007-2012
- Sloth-Nielsen, Julia, Kruuse, Helen
- Authors: Sloth-Nielsen, Julia , Kruuse, Helen
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68972 , vital:29344 , http://dx.doi.org/10.1163/15718182-02102005
- Description: Pre-print , This article represents the next in a series of five-year overviews of children’s rights in the courts in South Africa. Using the Convention on the Rights of the Child and the African Charter on the Welfare of Children as a point of departure, the study suggests that it is in the public sphere that children’s rights have had their most impact in the period under review. The article highlights eight areas of distinction in this five-year period: these include judicial approval of resource mobilisation for the fulfilment of children’s rights, emphasis on the quality of and standards in education; the development of innovative remedies to deal with unreasonable state measures affecting children, and an increasing focus on the right to dignity of the child. The authors conclude that the scope of the cases cited points to the growing insertion of children’s rights considerations in increasingly diverse areas of legal interaction. Furthermore, the authors posit that the CRC and ACRWC – together with non-binding sources of international law – have substantively informed and enriched the jurisprudence of South African courts.
- Full Text:
- Date Issued: 2013
- Authors: Sloth-Nielsen, Julia , Kruuse, Helen
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68972 , vital:29344 , http://dx.doi.org/10.1163/15718182-02102005
- Description: Pre-print , This article represents the next in a series of five-year overviews of children’s rights in the courts in South Africa. Using the Convention on the Rights of the Child and the African Charter on the Welfare of Children as a point of departure, the study suggests that it is in the public sphere that children’s rights have had their most impact in the period under review. The article highlights eight areas of distinction in this five-year period: these include judicial approval of resource mobilisation for the fulfilment of children’s rights, emphasis on the quality of and standards in education; the development of innovative remedies to deal with unreasonable state measures affecting children, and an increasing focus on the right to dignity of the child. The authors conclude that the scope of the cases cited points to the growing insertion of children’s rights considerations in increasingly diverse areas of legal interaction. Furthermore, the authors posit that the CRC and ACRWC – together with non-binding sources of international law – have substantively informed and enriched the jurisprudence of South African courts.
- Full Text:
- Date Issued: 2013
A proposed schema for the conditions of creativity in fine art studio practice
- Authors: Belluigi, Dina Z
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64641 , vital:28584 , http://www.ijea.org/v14n19/index.html
- Description: Drawing from creativity and art research, this paper proposes a schema for the conditions for creativity in fine art studio practice. Discussion focuses on how the triad of creative person, artmaking process, and artwork is constructed, and the situating of this creative triad within an enabling environment, which on a structural level includes the curriculum, and on a cultural and agential level involves teaching and learning relationships. An emphasis in placed on affective concerns, particularly the role of uncertainty as an important part of the art student’s learning experience.
- Full Text:
- Date Issued: 2013
- Authors: Belluigi, Dina Z
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64641 , vital:28584 , http://www.ijea.org/v14n19/index.html
- Description: Drawing from creativity and art research, this paper proposes a schema for the conditions for creativity in fine art studio practice. Discussion focuses on how the triad of creative person, artmaking process, and artwork is constructed, and the situating of this creative triad within an enabling environment, which on a structural level includes the curriculum, and on a cultural and agential level involves teaching and learning relationships. An emphasis in placed on affective concerns, particularly the role of uncertainty as an important part of the art student’s learning experience.
- Full Text:
- Date Issued: 2013
A qualitative ecological risk assessment of the invasive Nile tilapia, Oreochromis niloticus in a sub-tropical African river system (Limpopo River, South Africa)
- Zengeya, Tsungai A, Robertson, Mark P, Booth, Anthony J, Chimimba, Christian T
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123575 , vital:35457 , https://doi.10.1002/aqc.2258
- Description: 1. This study outlines the development of a qualitative risk assessment method and its application as a screening tool for determining the risk of establishment and spread of the invasive Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), within the central sub-catchment of the Limpopo River basin in northern South Africa. 2. The assessment used known physiological tolerance limits of O. niloticus in relation to minimum water temperature, presence or absence of dams, seasonality of river flows, and the presence of indigenous fish species of concern to identify river systems that would be suitable for O. niloticus establishment. 3. River sections along the Limpopo main river channel and the immediate reaches of its associated tributaries east of the Limpopo/Lephalala river confluence along the Botswana–South Africa–Zimbabwe border were identified as being highly vulnerable to O. niloticus invasion. Rivers in the upper Bushveld catchment (Upper Limpopo, Mogalakwena, Lephalala, Mokolo, Matlabas and Crocodile rivers) were categorized as of medium ecological risk, while headwater streams were considered to be of low ecological risk. The decrease in vulnerability between lowveld and highveld river sections was mainly a function of low water temperatures (8–12˚C) associated with increasing altitude. 4. Oreochromis niloticus is already established in the lower catchment of the Limpopo River basin where indigenous congenerics are at an extinction risk through hybridization and competition exclusion. Oreochromis niloticus, therefore, poses an ecologically unacceptable risk to river systems in the upper catchment where it is yet to establish. The current risk assessment model provides a useful preliminary framework for the identification of river systems that are vulnerable to an O. niloticus invasion where conservation measures should be directed and implemented to prevent its introduction and spread within the Limpopo river system.
- Full Text:
- Date Issued: 2013
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123575 , vital:35457 , https://doi.10.1002/aqc.2258
- Description: 1. This study outlines the development of a qualitative risk assessment method and its application as a screening tool for determining the risk of establishment and spread of the invasive Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), within the central sub-catchment of the Limpopo River basin in northern South Africa. 2. The assessment used known physiological tolerance limits of O. niloticus in relation to minimum water temperature, presence or absence of dams, seasonality of river flows, and the presence of indigenous fish species of concern to identify river systems that would be suitable for O. niloticus establishment. 3. River sections along the Limpopo main river channel and the immediate reaches of its associated tributaries east of the Limpopo/Lephalala river confluence along the Botswana–South Africa–Zimbabwe border were identified as being highly vulnerable to O. niloticus invasion. Rivers in the upper Bushveld catchment (Upper Limpopo, Mogalakwena, Lephalala, Mokolo, Matlabas and Crocodile rivers) were categorized as of medium ecological risk, while headwater streams were considered to be of low ecological risk. The decrease in vulnerability between lowveld and highveld river sections was mainly a function of low water temperatures (8–12˚C) associated with increasing altitude. 4. Oreochromis niloticus is already established in the lower catchment of the Limpopo River basin where indigenous congenerics are at an extinction risk through hybridization and competition exclusion. Oreochromis niloticus, therefore, poses an ecologically unacceptable risk to river systems in the upper catchment where it is yet to establish. The current risk assessment model provides a useful preliminary framework for the identification of river systems that are vulnerable to an O. niloticus invasion where conservation measures should be directed and implemented to prevent its introduction and spread within the Limpopo river system.
- Full Text:
- Date Issued: 2013
A ring-closing metathesis approach to eight-membered benzannelated scaffolds and subsequent internal alkene isomerizations
- Taher, Abu, Aderibigbe, Blessing A, Morgans, Garreth L, Madeley, Lee G, Khanye, Setshaba D, Van der Westhuizen, Leandi, Fernandes, Manuel A, Smith, Vincent J, Michael, Joseph P, Green, Ivan R, Van Otterlo, Willem A L
- Authors: Taher, Abu , Aderibigbe, Blessing A , Morgans, Garreth L , Madeley, Lee G , Khanye, Setshaba D , Van der Westhuizen, Leandi , Fernandes, Manuel A , Smith, Vincent J , Michael, Joseph P , Green, Ivan R , Van Otterlo, Willem A L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66252 , vital:28925 , https://doi.org/10.1016/j.tet.2012.12.043
- Description: publisher version , A set of eight-membered benzannelated heterocycles containing two heteroatoms (O,O, NR,NR and O,NR where R=protecting group) was synthesized by ring-closing metathesis from the corresponding ortho-bis-allyl precursors. In this manner, 7-methoxy-2,5-dihydro-1,6-benzodioxocine, 1,2,5,6-tetrahydro-1,6-benzodiazocines, 5,6-dihydro-2H-1,6-benzoxazocines and 5,6,9,10-tetrahydropyrido[2,3-b][1,4]diazocine were synthesized. A number of these compounds were then treated with the catalyst [RuClH(CO)(PPh3)3] to facilitate isomerization of the alkene into conjugation with the heteroatoms in the eight-membered ring. Quite surprisingly, an equal ratio of regioisomers was obtained, even if the heteroatoms were different.
- Full Text: false
- Date Issued: 2013
- Authors: Taher, Abu , Aderibigbe, Blessing A , Morgans, Garreth L , Madeley, Lee G , Khanye, Setshaba D , Van der Westhuizen, Leandi , Fernandes, Manuel A , Smith, Vincent J , Michael, Joseph P , Green, Ivan R , Van Otterlo, Willem A L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66252 , vital:28925 , https://doi.org/10.1016/j.tet.2012.12.043
- Description: publisher version , A set of eight-membered benzannelated heterocycles containing two heteroatoms (O,O, NR,NR and O,NR where R=protecting group) was synthesized by ring-closing metathesis from the corresponding ortho-bis-allyl precursors. In this manner, 7-methoxy-2,5-dihydro-1,6-benzodioxocine, 1,2,5,6-tetrahydro-1,6-benzodiazocines, 5,6-dihydro-2H-1,6-benzoxazocines and 5,6,9,10-tetrahydropyrido[2,3-b][1,4]diazocine were synthesized. A number of these compounds were then treated with the catalyst [RuClH(CO)(PPh3)3] to facilitate isomerization of the alkene into conjugation with the heteroatoms in the eight-membered ring. Quite surprisingly, an equal ratio of regioisomers was obtained, even if the heteroatoms were different.
- Full Text: false
- Date Issued: 2013
A source analysis of the conficker outbreak from a network telescope.
- Authors: Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429742 , vital:72636 , 10.23919/SAIEE.2013.8531865
- Description: This paper discusses a dataset of some 16 million packets targeting port 445/tcp collected by a network telescope utilising a /24 netblock in South African IP address space. An initial overview of the collected data is provided. This is followed by a detailed analysis of the packet characteristics observed, including size and TTL. The peculiarities of the observed target selection and the results of the flaw in the Conficker worm's propagation algorithm are presented. An analysis of the 4 million observed source hosts is reported, grouped by both packet counts and the number of distinct hosts per network address block. Address blocks of size /8, 16 and 24 are used for groupings. The localisation, by geographic region and numerical proximity, of high ranking aggregate netblocks is highlighted. The observed shift in geopolitical origins observed during the evolution of the Conficker worm is also discussed. The paper concludes with some overall analyses, and consideration of the application of network telescopes to the monitoring of such outbreaks in the future.
- Full Text:
- Date Issued: 2013
- Authors: Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429742 , vital:72636 , 10.23919/SAIEE.2013.8531865
- Description: This paper discusses a dataset of some 16 million packets targeting port 445/tcp collected by a network telescope utilising a /24 netblock in South African IP address space. An initial overview of the collected data is provided. This is followed by a detailed analysis of the packet characteristics observed, including size and TTL. The peculiarities of the observed target selection and the results of the flaw in the Conficker worm's propagation algorithm are presented. An analysis of the 4 million observed source hosts is reported, grouped by both packet counts and the number of distinct hosts per network address block. Address blocks of size /8, 16 and 24 are used for groupings. The localisation, by geographic region and numerical proximity, of high ranking aggregate netblocks is highlighted. The observed shift in geopolitical origins observed during the evolution of the Conficker worm is also discussed. The paper concludes with some overall analyses, and consideration of the application of network telescopes to the monitoring of such outbreaks in the future.
- Full Text:
- Date Issued: 2013
A study of the photophysicochemical and antimicrobial properties of two zinc phthalocyanine–silver nanoparticle conjugates
- Rapulenyane, Nomasonto, Antunes, Edith M, Nyokong, Tebello
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232522 , vital:49999 , xlink:href="https://doi.org/10.1039/C3NJ41107A"
- Description: This work reports conjugation of two mono carboxy substituted zinc phthalocyanines with glutathione capped silver nanoparticles (GSH-AgNPs). The photophysicochemical behaviour of the novel phthalocyanines–silver nanoparticle conjugates was investigated together with simple mixtures of the silver nanoparticles with low symmetry phthalocyanines (i.e. with no direct chemical bond formation). It was observed that upon conjugation of the phthalocyanines to the silver nanoparticles, a blue shifting of the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines alone. Fluorescence lifetimes and quantum yields decreased for conjugates compared to the phthalocyanines alone due to quenching caused by the silver nanoparticles. The low symmetry phthalocyanines and their conjugates showed antimicrobial activity against Escherichia coli in the presence and absence of light.
- Full Text:
- Date Issued: 2013
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232522 , vital:49999 , xlink:href="https://doi.org/10.1039/C3NJ41107A"
- Description: This work reports conjugation of two mono carboxy substituted zinc phthalocyanines with glutathione capped silver nanoparticles (GSH-AgNPs). The photophysicochemical behaviour of the novel phthalocyanines–silver nanoparticle conjugates was investigated together with simple mixtures of the silver nanoparticles with low symmetry phthalocyanines (i.e. with no direct chemical bond formation). It was observed that upon conjugation of the phthalocyanines to the silver nanoparticles, a blue shifting of the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines alone. Fluorescence lifetimes and quantum yields decreased for conjugates compared to the phthalocyanines alone due to quenching caused by the silver nanoparticles. The low symmetry phthalocyanines and their conjugates showed antimicrobial activity against Escherichia coli in the presence and absence of light.
- Full Text:
- Date Issued: 2013
Adsorption and separation of platinum and palladium by polyamine functionalized polystyrene-based beads and nanofibers
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Kempgens, Pierre F M, Antunes, Edith M, Torto, Nelson, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
Alternative/Experimental art spaces in Johannesburg:
- Authors: Malatjie, Portia
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147692 , vital:38661 , https://0-doi.org.wam.seals.ac.za/10.1080/09528822.2013.798181
- Description: There are a number of recent exciting developments in the Johannesburg alternative art scene. Alternative or experimental art spaces often exist as an alternative to commercial galleries and government or privately funded galleries as well as museums. They are therefore governed through a different set of rules, rules that often aim to transgress the institutional. These spaces, including the Parking Gallery, the Keleketla! Library and arguably the Wits School of Art's Substation gallery, invite debates about alternative art programming, collaborative art making and the necessity of institutional funding in order to maintain such spaces. In addition to these questions, it is pertinent to first determine what it is that classifies a space as alternative.
- Full Text:
- Date Issued: 2013
- Authors: Malatjie, Portia
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147692 , vital:38661 , https://0-doi.org.wam.seals.ac.za/10.1080/09528822.2013.798181
- Description: There are a number of recent exciting developments in the Johannesburg alternative art scene. Alternative or experimental art spaces often exist as an alternative to commercial galleries and government or privately funded galleries as well as museums. They are therefore governed through a different set of rules, rules that often aim to transgress the institutional. These spaces, including the Parking Gallery, the Keleketla! Library and arguably the Wits School of Art's Substation gallery, invite debates about alternative art programming, collaborative art making and the necessity of institutional funding in order to maintain such spaces. In addition to these questions, it is pertinent to first determine what it is that classifies a space as alternative.
- Full Text:
- Date Issued: 2013
An invader within an altered landscape: one catfish, two rivers and an inter-basin water transfer scheme
- Kadye, Wilbert T, Booth, Anthony J
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123776 , vital:35494 , https://doi.10.1002/rra.2599
- Description: African sharptooth catfish Clarias gariepinus has become established as a non-native invasive species in Eastern Cape, South Africa, where it was translocated primarily through an inter-basin water transfer scheme into the Great Fish and Sundays rivers. This study examined the patterns in catfish distribution and abundance, and compared trophic niches in relation to the ichthyofauna of the two rivers. Correspondence analysis revealed upstream to downstream gradients associated with the spatial distribution in species richness for most species within the mainstream and mainstream to tributary gradients that were associated mostly with the spatial distribution of native minnows in both rivers. Catfish was predicted to occur widely within the mainstream habitats and to decrease progressively from mainstreams to tributaries. Based on classification and regression trees, the physico-chemical environment was found to be a good proxy for predicting the occurrence and abundance of catfish. Although non-significant relationships were observed between catfish and other native fish species abundances, the study suggests potential impact due to predation and interference in habitats where the invader co-occurs with other fishes. Comparisons of trophic niches indicated higher trophic diversity for the mainstream ichthyofauna than the tributary communities in both rivers, suggesting an upstream to downstream continuum in community structure and resource availability. Catfish within the invaded mainstream had comparable trophic niches and similar dispersion patterns among individuals for both rivers, but indicated differences in shapes of scatter. This suggests that the catfish exhibited a differential response, probably in relation to resource availability, that may be indicative of its dietary plasticity. The study suggests the proliferation of catfish and its probable impact within the mainstream flow-altered habitats where invasion resistance was possibly reduced. Comparisons of trophic niches provided information on its probable impact at different scales and the potential risk of invasion of tributaries inhabited by native minnow species.
- Full Text:
- Date Issued: 2013
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123776 , vital:35494 , https://doi.10.1002/rra.2599
- Description: African sharptooth catfish Clarias gariepinus has become established as a non-native invasive species in Eastern Cape, South Africa, where it was translocated primarily through an inter-basin water transfer scheme into the Great Fish and Sundays rivers. This study examined the patterns in catfish distribution and abundance, and compared trophic niches in relation to the ichthyofauna of the two rivers. Correspondence analysis revealed upstream to downstream gradients associated with the spatial distribution in species richness for most species within the mainstream and mainstream to tributary gradients that were associated mostly with the spatial distribution of native minnows in both rivers. Catfish was predicted to occur widely within the mainstream habitats and to decrease progressively from mainstreams to tributaries. Based on classification and regression trees, the physico-chemical environment was found to be a good proxy for predicting the occurrence and abundance of catfish. Although non-significant relationships were observed between catfish and other native fish species abundances, the study suggests potential impact due to predation and interference in habitats where the invader co-occurs with other fishes. Comparisons of trophic niches indicated higher trophic diversity for the mainstream ichthyofauna than the tributary communities in both rivers, suggesting an upstream to downstream continuum in community structure and resource availability. Catfish within the invaded mainstream had comparable trophic niches and similar dispersion patterns among individuals for both rivers, but indicated differences in shapes of scatter. This suggests that the catfish exhibited a differential response, probably in relation to resource availability, that may be indicative of its dietary plasticity. The study suggests the proliferation of catfish and its probable impact within the mainstream flow-altered habitats where invasion resistance was possibly reduced. Comparisons of trophic niches provided information on its probable impact at different scales and the potential risk of invasion of tributaries inhabited by native minnow species.
- Full Text:
- Date Issued: 2013
An overview of normative frameworks for the protection of development-induced IDPs in Kenya.
- Authors: Juma, Laurence
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127112 , vital:35957 , https://doi.org/10.1163/17087384-12342016
- Description: Based on the assumption that development induced displacement brings new challenges that the existing protection frameworks may not be aptly suited to deal with, this article analyses how the existing laws have met this challenge and the prospects for further improvement. While its focus is on Kenya, it evaluates the normative quality of protection and standards offered by regional instruments against the existing, as well emerging, parameters for implementation at the domestic level. In this regard, the article examines the propriety of Kenya’s newly promulgated law on internal displacement in providing for protection for the development induced IDPs, the implementation programme that it establishes and its prospects for furthering the vision of the UN Guiding Principles on Internally Displaced and other regional instruments.
- Full Text:
- Date Issued: 2013
- Authors: Juma, Laurence
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127112 , vital:35957 , https://doi.org/10.1163/17087384-12342016
- Description: Based on the assumption that development induced displacement brings new challenges that the existing protection frameworks may not be aptly suited to deal with, this article analyses how the existing laws have met this challenge and the prospects for further improvement. While its focus is on Kenya, it evaluates the normative quality of protection and standards offered by regional instruments against the existing, as well emerging, parameters for implementation at the domestic level. In this regard, the article examines the propriety of Kenya’s newly promulgated law on internal displacement in providing for protection for the development induced IDPs, the implementation programme that it establishes and its prospects for furthering the vision of the UN Guiding Principles on Internally Displaced and other regional instruments.
- Full Text:
- Date Issued: 2013
An Unprecedented 'Precedent'?: Phodiclinics (Pty) Ltd v Pinehaven Private Hospital (Pty) Ltd (594/2010)[2011] ZASCA163 (28 September 2011); 2011 4 All SA 331 (SCA)
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69950 , vital:29598 , https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2364288
- Description: There are some fundamental underlying requirements that need to be in place for a system of precedent to operate. Of these I wish to isolate two that are germane to this note. The first is that court decisions (especially those in which a written judgment is handed down) need to be clearly reasoned and logically articulated to be understandable, effective and to have value in a system of precedent that finds its ultimate lodestar in the rule of law. There is no constitutional or statutory requirement that a court in all cases must furnish reasons, or even written reasons, for its decision But the practice of doing so, the Constitutional Court has said, supports the rule of law, ensuring that judicial decision-making does not occur in a manner that is arbitrary, and ensures that judges may be held accountable for their decisions. The second requirement is a technical rule – the rule of majority: if the case is heard by a full bench, and where differing opinions are handed down by the judges hearing the case, the ratio decidendi can only be identified from those judges whose reasoning is in the majority.
- Full Text: false
- Date Issued: 2013
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69950 , vital:29598 , https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2364288
- Description: There are some fundamental underlying requirements that need to be in place for a system of precedent to operate. Of these I wish to isolate two that are germane to this note. The first is that court decisions (especially those in which a written judgment is handed down) need to be clearly reasoned and logically articulated to be understandable, effective and to have value in a system of precedent that finds its ultimate lodestar in the rule of law. There is no constitutional or statutory requirement that a court in all cases must furnish reasons, or even written reasons, for its decision But the practice of doing so, the Constitutional Court has said, supports the rule of law, ensuring that judicial decision-making does not occur in a manner that is arbitrary, and ensures that judges may be held accountable for their decisions. The second requirement is a technical rule – the rule of majority: if the case is heard by a full bench, and where differing opinions are handed down by the judges hearing the case, the ratio decidendi can only be identified from those judges whose reasoning is in the majority.
- Full Text: false
- Date Issued: 2013
Analysing learning at the interface of scientific and traditional ecological knowledge in a mangrove ecosystem restoration scenario in the eastern coast of Tanzania
- Sabai, Daniel, Sisitka, Heila
- Authors: Sabai, Daniel , Sisitka, Heila
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127179 , vital:35974 , https://doi.org/10.2478/trser-2013-0027
- Description: Records from community-based coastal management initiatives indicate that local communities who are key actors in activities that aim at safeguarding the health status of terrestrial and marine ecosystems face a lot of challenges associated with adapting andapplying indicators that are scientifically abstracted and methodologically too reified, given varying social, contextual and technical conditions prevailing amongst them. This paper brings into view possible challenges of adapting and applying scientific indicators in community-based monitoring of mangrove ecosystem and suggests a new approach that may lead to development of indicators which are less reified, more congruent to users (coastal communities) and likely to attract a wider social learning in the mangroverestoration context. It also sets a bridge for scientific institutions (including universities), tounderstand various social, cultural and contextual needs that determine epistemological access between them and local communities, which need to be addressed prior to engaging targetcommunities in participatory monitoring programmes.The paper attempts to analyse learning at the interface of knowledge that scientific institutions produce and the potential knowledge that exists in local context (traditional ecological knowledge) for purposes of widening and improving knowledge sharing and safeguarding the health status of mangrove species and fisheries that use them as key habitats. The paper stems from a study which employs processes of abstraction and experiential learning techniques such as Experiential Learning Intervention Workshop carried out in 2012,to unlock knowledge that local communities have, as an input for underlabouring existing scientific indicators in the eastern coast of Tanzania.It brings into view the need to consider contextual realities on ground, the level of education that the participating group has, the minimum level of participation that is required, structures that govern coastal monitoring practices at local level and the need for scientific institutions to consider the knowledge that local people have as an input for enhancing or improving coastal monitoring, especially monitoring of mangrove and fishery resources. The paper finally comes up with a framework of indicators which is regarded by coastal communities as being less reified, more contextually and culturally congruent and which can easily be used in detecting environmental trends, threats, changes and conditions of mangrove and fisheries resources, and attract wider social learning processes.
- Full Text:
- Date Issued: 2013
- Authors: Sabai, Daniel , Sisitka, Heila
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127179 , vital:35974 , https://doi.org/10.2478/trser-2013-0027
- Description: Records from community-based coastal management initiatives indicate that local communities who are key actors in activities that aim at safeguarding the health status of terrestrial and marine ecosystems face a lot of challenges associated with adapting andapplying indicators that are scientifically abstracted and methodologically too reified, given varying social, contextual and technical conditions prevailing amongst them. This paper brings into view possible challenges of adapting and applying scientific indicators in community-based monitoring of mangrove ecosystem and suggests a new approach that may lead to development of indicators which are less reified, more congruent to users (coastal communities) and likely to attract a wider social learning in the mangroverestoration context. It also sets a bridge for scientific institutions (including universities), tounderstand various social, cultural and contextual needs that determine epistemological access between them and local communities, which need to be addressed prior to engaging targetcommunities in participatory monitoring programmes.The paper attempts to analyse learning at the interface of knowledge that scientific institutions produce and the potential knowledge that exists in local context (traditional ecological knowledge) for purposes of widening and improving knowledge sharing and safeguarding the health status of mangrove species and fisheries that use them as key habitats. The paper stems from a study which employs processes of abstraction and experiential learning techniques such as Experiential Learning Intervention Workshop carried out in 2012,to unlock knowledge that local communities have, as an input for underlabouring existing scientific indicators in the eastern coast of Tanzania.It brings into view the need to consider contextual realities on ground, the level of education that the participating group has, the minimum level of participation that is required, structures that govern coastal monitoring practices at local level and the need for scientific institutions to consider the knowledge that local people have as an input for enhancing or improving coastal monitoring, especially monitoring of mangrove and fishery resources. The paper finally comes up with a framework of indicators which is regarded by coastal communities as being less reified, more contextually and culturally congruent and which can easily be used in detecting environmental trends, threats, changes and conditions of mangrove and fisheries resources, and attract wider social learning processes.
- Full Text:
- Date Issued: 2013
Analysis of protein thermostability enhancing factors in industrially important thermus bacteria species
- Kumwenda, Benjamin, Litthauer, Derek, Tastan Bishop, Özlem, Reva, Oleg
- Authors: Kumwenda, Benjamin , Litthauer, Derek , Tastan Bishop, Özlem , Reva, Oleg
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123085 , vital:35404 , https://doi.10.4137/EBO.S12539
- Description: Elucidation of evolutionary factors that enhance protein thermostability is a critical problem and was the focus of this work on Thermus species. Pairs of orthologous sequences of T. scotoductus SA-01 and T. thermophilus HB27, with the largest negative minimum folding energy (MFE) as predicted by the UNAFold algorithm, were statistically analyzed. Favored substitutions of amino acids residues and their properties were determined. Substitutions were analyzed in modeled protein structures to determine their locations and contribution to energy differences using PyMOL and FoldX programs respectively. Dominant trends in amino acid substitutions consistent with differences in thermostability between orthologous sequences were observed. T. thermophilus thermophilic proteins showed an increase in non-polar, tiny, and charged amino acids. An abundance of alanine substituted by serine and threonine, as well as arginine substituted by glutamine and lysine was observed in T. thermophilus HB27. Structural comparison showed that stabilizing mutations occurred on surfaces and loops in protein structures.
- Full Text:
- Date Issued: 2013
- Authors: Kumwenda, Benjamin , Litthauer, Derek , Tastan Bishop, Özlem , Reva, Oleg
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123085 , vital:35404 , https://doi.10.4137/EBO.S12539
- Description: Elucidation of evolutionary factors that enhance protein thermostability is a critical problem and was the focus of this work on Thermus species. Pairs of orthologous sequences of T. scotoductus SA-01 and T. thermophilus HB27, with the largest negative minimum folding energy (MFE) as predicted by the UNAFold algorithm, were statistically analyzed. Favored substitutions of amino acids residues and their properties were determined. Substitutions were analyzed in modeled protein structures to determine their locations and contribution to energy differences using PyMOL and FoldX programs respectively. Dominant trends in amino acid substitutions consistent with differences in thermostability between orthologous sequences were observed. T. thermophilus thermophilic proteins showed an increase in non-polar, tiny, and charged amino acids. An abundance of alanine substituted by serine and threonine, as well as arginine substituted by glutamine and lysine was observed in T. thermophilus HB27. Structural comparison showed that stabilizing mutations occurred on surfaces and loops in protein structures.
- Full Text:
- Date Issued: 2013
Ancient and modern hybridization between Lucilia sericata and L. cuprina (Diptera: Calliphoridae)
- Williams, Kirstin A, Villet, Martin H
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442633 , vital:74017 , 10.14411/eje.2013.029
- Description: There are important but inconsistent differences in breeding site preference between the blow flies Lucilia sericata (Meigen, 1826) and L. cuprina (Wiedemann, 1830)(Diptera: Calliphoridae) that have significance for medical and veterinary science. These inconsistencies might arise from hybridisation. The species are difficult to distinguish using external morphology, although the male genitalia are distinctive and there are reliable molecular markers. Molecular evidence of modern hybridisation, derived from a newly developed nuclear marker, the period (per) gene, is presented here. This has implications for identifications of these species based on mtDNA, and may lead to an explanation of the medical and veterinary anomalies noted in these species.
- Full Text:
- Date Issued: 2013
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442633 , vital:74017 , 10.14411/eje.2013.029
- Description: There are important but inconsistent differences in breeding site preference between the blow flies Lucilia sericata (Meigen, 1826) and L. cuprina (Wiedemann, 1830)(Diptera: Calliphoridae) that have significance for medical and veterinary science. These inconsistencies might arise from hybridisation. The species are difficult to distinguish using external morphology, although the male genitalia are distinctive and there are reliable molecular markers. Molecular evidence of modern hybridisation, derived from a newly developed nuclear marker, the period (per) gene, is presented here. This has implications for identifications of these species based on mtDNA, and may lead to an explanation of the medical and veterinary anomalies noted in these species.
- Full Text:
- Date Issued: 2013
Applying a student curriculum discourse in higher education teaching and learning
- Mndzebele, Samuel, McKenna, Sioux
- Authors: Mndzebele, Samuel , McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187417 , vital:44633 , xlink:href="https://doi.org/10.1080/18146627.2013.786210"
- Description: Indications of poor quality in students’ written work necessitated the need for deeper investigations aimed at designing and applying appropriate teaching/learning and assessment innovations in the course curriculum. The project-exercise engaged a conceptual-explorative approach through: reviews/investigations; educational diagnosis; design/application of innovations and evaluation processes. In addition to other challenges, diagnosed problems included: students’ ignorance on key curriculum components; imbalance in teaching/learning and assessment tasks engaging all 3-learning domains; less intensiveness of the e-learning mode; and superficial formative feedback. Included a “Student-Curriculum-Discourse” self-tutorial guide, and tasks alignment of the teaching/learning and assessment. Learners’ performance can be improved through a curriculum-discourse self-tutorial exercise, complemented with: intellectual, social, experiential, and emotional structures. Both educators and learners share specific responsibilities in the teaching/learning environment. There is need to expand/probe the theoretical dimension within which the on-line distance education occurs.
- Full Text:
- Date Issued: 2013
- Authors: Mndzebele, Samuel , McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187417 , vital:44633 , xlink:href="https://doi.org/10.1080/18146627.2013.786210"
- Description: Indications of poor quality in students’ written work necessitated the need for deeper investigations aimed at designing and applying appropriate teaching/learning and assessment innovations in the course curriculum. The project-exercise engaged a conceptual-explorative approach through: reviews/investigations; educational diagnosis; design/application of innovations and evaluation processes. In addition to other challenges, diagnosed problems included: students’ ignorance on key curriculum components; imbalance in teaching/learning and assessment tasks engaging all 3-learning domains; less intensiveness of the e-learning mode; and superficial formative feedback. Included a “Student-Curriculum-Discourse” self-tutorial guide, and tasks alignment of the teaching/learning and assessment. Learners’ performance can be improved through a curriculum-discourse self-tutorial exercise, complemented with: intellectual, social, experiential, and emotional structures. Both educators and learners share specific responsibilities in the teaching/learning environment. There is need to expand/probe the theoretical dimension within which the on-line distance education occurs.
- Full Text:
- Date Issued: 2013
Assessment of potential anti-cancer stem cell activity of marine algal compounds using an in vitro mammosphere assay:
- de la Mare, Jo-Anne, Sterrenberg, Jason N, Sukhthankar, Mugdha G, Chiwakata, Maynard T, Beukes, Denzil R, Blatch, Gregory L, Edkins, Adrienne L
- Authors: de la Mare, Jo-Anne , Sterrenberg, Jason N , Sukhthankar, Mugdha G , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165184 , vital:41216 , DOI: 10.1186/1475-2867-13-39
- Description: The cancer stem cell (CSC) theory proposes that tumours arise from and are sustained by a subpopulation of cells with both cancer and stem cell properties. One of the key hallmarks of CSCs is the ability to grow anchorage-independently under serum-free culture conditions resulting in the formation of tumourspheres. It has further been reported that these cells are resistant to traditional chemotherapeutic agents.
- Full Text:
- Date Issued: 2013
- Authors: de la Mare, Jo-Anne , Sterrenberg, Jason N , Sukhthankar, Mugdha G , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165184 , vital:41216 , DOI: 10.1186/1475-2867-13-39
- Description: The cancer stem cell (CSC) theory proposes that tumours arise from and are sustained by a subpopulation of cells with both cancer and stem cell properties. One of the key hallmarks of CSCs is the ability to grow anchorage-independently under serum-free culture conditions resulting in the formation of tumourspheres. It has further been reported that these cells are resistant to traditional chemotherapeutic agents.
- Full Text:
- Date Issued: 2013
Audio Device Representation, Control, and Monitoring Using SNMP
- Eales, Andrew, Foss, Richard
- Authors: Eales, Andrew , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426855 , vital:72396 , https://www.aes.org/e-lib/browse.cfm?elib=17012
- Description: The Simple Network Management Protocol (SNMP) is widely used to configure and monitor networked devices. The architecture of complex audio devices can be elegantly represented using SNMP tables. Carefully considered table indexing schemes support a logical device model that can be accessed using standard SNMP commands. This paper examines the use of SNMP tables to represent the architecture of audio devices. A representational scheme that uses table indexes to provide direct-access to context-sensitive SNMP data objects is presented. The monitoring of parameter values and the implementation of connection management using SNMP are also discussed.
- Full Text:
- Date Issued: 2013
- Authors: Eales, Andrew , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426855 , vital:72396 , https://www.aes.org/e-lib/browse.cfm?elib=17012
- Description: The Simple Network Management Protocol (SNMP) is widely used to configure and monitor networked devices. The architecture of complex audio devices can be elegantly represented using SNMP tables. Carefully considered table indexing schemes support a logical device model that can be accessed using standard SNMP commands. This paper examines the use of SNMP tables to represent the architecture of audio devices. A representational scheme that uses table indexes to provide direct-access to context-sensitive SNMP data objects is presented. The monitoring of parameter values and the implementation of connection management using SNMP are also discussed.
- Full Text:
- Date Issued: 2013
Automated classification of computer network attacks
- van Heerden, Renier, Leenen, Louise, Irwin, Barry V W
- Authors: van Heerden, Renier , Leenen, Louise , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429622 , vital:72627 , 10.1109/ICASTech.2013.6707510
- Description: In this paper we demonstrate how an automated reasoner, HermiT, is used to classify instances of computer network based attacks in conjunction with a network attack ontology. The ontology describes different types of network attacks through classes and inter-class relationships and has previously been implemented in the Protege ontology editor. Two significant recent instances of network based attacks are presented as individuals in the ontology and correctly classified by the automated reasoner according to the relevant types of attack scenarios depicted in the ontology. The two network attack instances are the Distributed Denial of Service attack on SpamHaus in 2013 and the theft of 42 million Rand ($6.7 million) from South African Postbank in 2012.
- Full Text:
- Date Issued: 2013
- Authors: van Heerden, Renier , Leenen, Louise , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429622 , vital:72627 , 10.1109/ICASTech.2013.6707510
- Description: In this paper we demonstrate how an automated reasoner, HermiT, is used to classify instances of computer network based attacks in conjunction with a network attack ontology. The ontology describes different types of network attacks through classes and inter-class relationships and has previously been implemented in the Protege ontology editor. Two significant recent instances of network based attacks are presented as individuals in the ontology and correctly classified by the automated reasoner according to the relevant types of attack scenarios depicted in the ontology. The two network attack instances are the Distributed Denial of Service attack on SpamHaus in 2013 and the theft of 42 million Rand ($6.7 million) from South African Postbank in 2012.
- Full Text:
- Date Issued: 2013
Axial coordination of zinc and silicon phthalocyanines to silver and gold nanoparticles: an investigation of their photophysicochemical and antimicrobial behavior
- Masilela, Nkosiphile, Antunes, Edith M, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241818 , vital:50972 , xlink:href="https://doi.org/10.1142/S1088424613500016"
- Description: This work reports on the axial coordination of zinc phthalocyanine and bis-(1,6-hexanedithiol) silicon phthalocyanine to silver and gold nanoparticles. Red shifting of absorption spectra of the phthalocyanine complexes was observed after conjugation with the nanoparticles. An improvement in the photophysicochemical behavior and antimicrobial activity was achieved in the presence of metal nanoparticles for both complexes. A decrease in triplet lifetimes was observed for all the phthalocyanine metal nanoparticle conjugates. The Zn phthalocyanine complex gave the highest triplet and singlet oxygen quantum yield in the presence of gold nanoparticles. On the other hand, the bacterial inhibition was found to be best for the Si phthalocyanine derivative in the presence of nanoparticles compared to the Zn phthalocyanine counterpart. The highest antimicrobial activity was achieved for both conjugates against B. subtilis compared to S. aureaus both in the dark and under illumination with light.
- Full Text:
- Date Issued: 2013
- Authors: Masilela, Nkosiphile , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241818 , vital:50972 , xlink:href="https://doi.org/10.1142/S1088424613500016"
- Description: This work reports on the axial coordination of zinc phthalocyanine and bis-(1,6-hexanedithiol) silicon phthalocyanine to silver and gold nanoparticles. Red shifting of absorption spectra of the phthalocyanine complexes was observed after conjugation with the nanoparticles. An improvement in the photophysicochemical behavior and antimicrobial activity was achieved in the presence of metal nanoparticles for both complexes. A decrease in triplet lifetimes was observed for all the phthalocyanine metal nanoparticle conjugates. The Zn phthalocyanine complex gave the highest triplet and singlet oxygen quantum yield in the presence of gold nanoparticles. On the other hand, the bacterial inhibition was found to be best for the Si phthalocyanine derivative in the presence of nanoparticles compared to the Zn phthalocyanine counterpart. The highest antimicrobial activity was achieved for both conjugates against B. subtilis compared to S. aureaus both in the dark and under illumination with light.
- Full Text:
- Date Issued: 2013