Characterization of porphyrin nanorods on fluorine doped tin oxide glass sheet
- George, Reama C, Falgenhauer, Jane, Geis, Clemens, Nyokong, Tebello, Schlettwein, Derck
- Authors: George, Reama C , Falgenhauer, Jane , Geis, Clemens , Nyokong, Tebello , Schlettwein, Derck
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193542 , vital:45344 , xlink:href="https://doi.org/10.1142/S1088424615500923"
- Description: Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS4)4) served as negatively charged counterpart for the positively charged metallo meso-tetra(4-NN-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During cyclic voltammetry either applying negative potentials from 0.0 V to -1.0 V or positive potentials from 0.0 V to ++2.2 V irreversible reduction or oxidation reactions were detected for the films. Consistently, SEM images taken following cyclic voltammetry showed the disintegration of the PNR on the films into smaller subunits. Spectroelectrochemical measurements showed the formation of porphyrin anionic radicals during oxidation by a decrease in the absorption intensities and broadening of spectra with an additional band appearing around 900 nm. A similar trend was observed when negative potentials were applied but in this case the cationic radical was produced. In both cases the decrease of the intensity of the J-aggregate confirms a loss of intermolecular coupling, again consistent with the smaller subunits observed in SEM analysis.
- Full Text:
- Date Issued: 2015
- Authors: George, Reama C , Falgenhauer, Jane , Geis, Clemens , Nyokong, Tebello , Schlettwein, Derck
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193542 , vital:45344 , xlink:href="https://doi.org/10.1142/S1088424615500923"
- Description: Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS4)4) served as negatively charged counterpart for the positively charged metallo meso-tetra(4-NN-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During cyclic voltammetry either applying negative potentials from 0.0 V to -1.0 V or positive potentials from 0.0 V to ++2.2 V irreversible reduction or oxidation reactions were detected for the films. Consistently, SEM images taken following cyclic voltammetry showed the disintegration of the PNR on the films into smaller subunits. Spectroelectrochemical measurements showed the formation of porphyrin anionic radicals during oxidation by a decrease in the absorption intensities and broadening of spectra with an additional band appearing around 900 nm. A similar trend was observed when negative potentials were applied but in this case the cationic radical was produced. In both cases the decrease of the intensity of the J-aggregate confirms a loss of intermolecular coupling, again consistent with the smaller subunits observed in SEM analysis.
- Full Text:
- Date Issued: 2015
Classification System for Wetlands and Other Aquatic Ecosystems in South Africa:
- Authors: Ellery, William F N
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144454 , vital:38347 , https://doi.org/10.2989/10220119.2015.1025843
- Description: There have been several attempts to develop a wetland classification for South Africa, with merit in each, but a system that satisfies the needs of a wide range of professionals has been elusive. This is partly to be expected since classification systems are often user-specific. Nevertheless, and at last, the authors of Classification System for Wetlands and Other Aquatic Ecosystems in South Africa. User Manual: Inland Systems (SANBI Biodiversity Series 22) have developed a robust and comprehensive wetland classification system for South Africa that likely will have broad appeal and be widely used. Working for Wetlands, the Water Research Commission (WRC) and SANBI provided considerable support for the development of this system and there was expert input from a wide range of stakeholders.
- Full Text:
- Date Issued: 2015
- Authors: Ellery, William F N
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144454 , vital:38347 , https://doi.org/10.2989/10220119.2015.1025843
- Description: There have been several attempts to develop a wetland classification for South Africa, with merit in each, but a system that satisfies the needs of a wide range of professionals has been elusive. This is partly to be expected since classification systems are often user-specific. Nevertheless, and at last, the authors of Classification System for Wetlands and Other Aquatic Ecosystems in South Africa. User Manual: Inland Systems (SANBI Biodiversity Series 22) have developed a robust and comprehensive wetland classification system for South Africa that likely will have broad appeal and be widely used. Working for Wetlands, the Water Research Commission (WRC) and SANBI provided considerable support for the development of this system and there was expert input from a wide range of stakeholders.
- Full Text:
- Date Issued: 2015
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
Comparisons of isotopic niche widths of some invasive and indigenous fauna in a South African river
- Hill, Jaclyn M, Jones, Roy W, Hill, Martin P, Weyl, Olaf L F
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
Condoms in pockets and HIV-free certificates: mother-daughter communication about sex and risk in a time of AIDS epidemic in South Africa
- Authors: Wilbraham, Lindy
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143693 , vital:38274 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Responsive to the perceived high risks of sexual coercion, unwanted pregnancy and HIV-infection of girls in particular, several South African sexual health promotion campaigns have used media targeting parents (mothers in particular) to instruct them on how sex should be talked about with young people to ‘risk-proof’ them. Such an instrumentalist public health discourse posits this intergenerational communication as an ‘ongoing discussion’ of events, feelings, issues and risk-safe practices around heterosexual sex negotiation. A Foucauldian view finds these conversational imperatives pitched against much-talked-about resistances to talking about sex; and the saturation with risk of ambivalent mothers and silent daughters. Mother-daughter communication about sex and sexualities – as an uneasy western ideal of attachment parenting – has tangled roots in psychoanalytic theory and feminisms where sex as the core of modern subjectivity is normalized, capacities for intimacy are trained, and affiliative sexuality is modelled in ways that balance the rights and responsibilities of sexual agency/citizenship. This paper begins with two narrative fragments from a sexual health campaign that addressed mothers and daughters, and recounts how these ‘stories’ produced derisive laughter when introduced into group discussions with young/older women. The paper follows two lines of exploration. Firstly, is western idealized fabrication of inter-subjectivity between mothers and daughters desirable and feasible in post-apartheid conditions of epidemic in South Africa? And secondly, what if the narratives of lives and experiences we offer by way of health education materials provoke uncertainties, gaps and interrogations about sex, mothering and communication, instead of offering homilies and solutions?
- Full Text:
- Date Issued: 2015
- Authors: Wilbraham, Lindy
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143693 , vital:38274 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Responsive to the perceived high risks of sexual coercion, unwanted pregnancy and HIV-infection of girls in particular, several South African sexual health promotion campaigns have used media targeting parents (mothers in particular) to instruct them on how sex should be talked about with young people to ‘risk-proof’ them. Such an instrumentalist public health discourse posits this intergenerational communication as an ‘ongoing discussion’ of events, feelings, issues and risk-safe practices around heterosexual sex negotiation. A Foucauldian view finds these conversational imperatives pitched against much-talked-about resistances to talking about sex; and the saturation with risk of ambivalent mothers and silent daughters. Mother-daughter communication about sex and sexualities – as an uneasy western ideal of attachment parenting – has tangled roots in psychoanalytic theory and feminisms where sex as the core of modern subjectivity is normalized, capacities for intimacy are trained, and affiliative sexuality is modelled in ways that balance the rights and responsibilities of sexual agency/citizenship. This paper begins with two narrative fragments from a sexual health campaign that addressed mothers and daughters, and recounts how these ‘stories’ produced derisive laughter when introduced into group discussions with young/older women. The paper follows two lines of exploration. Firstly, is western idealized fabrication of inter-subjectivity between mothers and daughters desirable and feasible in post-apartheid conditions of epidemic in South Africa? And secondly, what if the narratives of lives and experiences we offer by way of health education materials provoke uncertainties, gaps and interrogations about sex, mothering and communication, instead of offering homilies and solutions?
- Full Text:
- Date Issued: 2015
Constructing sexualities: a critical overview of articles published in Feminism and Psychology
- Marx, Jacqueline, Donaldson, Natalie
- Authors: Marx, Jacqueline , Donaldson, Natalie
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142040 , vital:38044 , DOI: 10.1177/0959353515572704
- Description: How have sexualities been dealt with in articles published in Feminism and Psychology since the inception of the journal in 1991? The idea for this overview arose from our experience of designing a critical sexualities course for graduate students in psychology. The articles featured in this overview form part of a Virtual Special Issue that can be located on the Feminism and Psychology website. Virtual Special Issues (VSI) are collections of previously published articles, which have been compiled by guest editors who are experts in the field. VSIs provide readers with an overview of feminist thought about a topic or theme, as well as an easy way to locate pertinent articles. Scholars who are approaching a new topic may find a VSI especially useful, as will instructors who are preparing course syllabi. This article introduces the Constructing Sexualities VSI.
- Full Text:
- Date Issued: 2015
- Authors: Marx, Jacqueline , Donaldson, Natalie
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142040 , vital:38044 , DOI: 10.1177/0959353515572704
- Description: How have sexualities been dealt with in articles published in Feminism and Psychology since the inception of the journal in 1991? The idea for this overview arose from our experience of designing a critical sexualities course for graduate students in psychology. The articles featured in this overview form part of a Virtual Special Issue that can be located on the Feminism and Psychology website. Virtual Special Issues (VSI) are collections of previously published articles, which have been compiled by guest editors who are experts in the field. VSIs provide readers with an overview of feminist thought about a topic or theme, as well as an easy way to locate pertinent articles. Scholars who are approaching a new topic may find a VSI especially useful, as will instructors who are preparing course syllabi. This article introduces the Constructing Sexualities VSI.
- Full Text:
- Date Issued: 2015
Counsellors’ constructions of intimate partner violence (IPV) during pregnancy and their interventions with women suffering such IPV:
- Fleischack, Annie, Macleod, Catriona I, Böhmke, Werner
- Authors: Fleischack, Annie , Macleod, Catriona I , Böhmke, Werner
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143716 , vital:38276 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: South African research reveals a high prevalence of intimate partner violence (IPV) yet little research exists regarding IPV during pregnancy. In this paper we present data collected through narrative interviews with eight counsellors from two NGOs working with women experiencing IPV during pregnancy. Using a narrative-discursive analytical lens, attention was given to the construction of subject positions and power relations between the men and women in the counsellors’ narratives. Men were largely positioned as subscribing to violent patriarchal behaviour whilst women were mostly positioned as nurturing, and as victims. The counsellors saw IPV during pregnancy as occurring for a variety of reasons, including conflicts around abortion, and male partners finding the women physically unattractive. It was noted that IPV during pregnancy is managed by women in complex ways. Counsellors’ emphasis on individual counselling and leaving the IPV relationship suggests that women are ultimately responsible for their own wellbeing and success.
- Full Text:
- Date Issued: 2015
- Authors: Fleischack, Annie , Macleod, Catriona I , Böhmke, Werner
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143716 , vital:38276 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: South African research reveals a high prevalence of intimate partner violence (IPV) yet little research exists regarding IPV during pregnancy. In this paper we present data collected through narrative interviews with eight counsellors from two NGOs working with women experiencing IPV during pregnancy. Using a narrative-discursive analytical lens, attention was given to the construction of subject positions and power relations between the men and women in the counsellors’ narratives. Men were largely positioned as subscribing to violent patriarchal behaviour whilst women were mostly positioned as nurturing, and as victims. The counsellors saw IPV during pregnancy as occurring for a variety of reasons, including conflicts around abortion, and male partners finding the women physically unattractive. It was noted that IPV during pregnancy is managed by women in complex ways. Counsellors’ emphasis on individual counselling and leaving the IPV relationship suggests that women are ultimately responsible for their own wellbeing and success.
- Full Text:
- Date Issued: 2015
Cultural values of natural resources among the San people neighbouring Kgalagadi Transfrontier Park, South Africa
- Thondhlana, Gladman, Shackleton, Sheona E
- Authors: Thondhlana, Gladman , Shackleton, Sheona E
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67699 , vital:29131 , https://doi.org/10.1080/13549839.2013.818950
- Description: Publisher version , Globally, cultural values of natural resources are increasingly recognised as important for local natural resource management and conservation in and beyond parks. The tendency has been to focus on the direct-use rather than the cultural values and importance of natural resources. The cultural values underlying natural resources (directly or indirectly used) and various natural resource-based activities, and the implications for conservation, remain little explored. Drawing from household surveys, in-depth qualitative interviews, observations and secondary data, we explore the cultural significance of natural resources and different land-use practices among the San people bordering Kgalagadi Transfrontier Park in South Africa. Our findings illustrate that though cultural values are inextricably linked to resource use, they are not recognised by all community members. Further, cultural values arise from a diverse and sometimes conflicting array of values that punctuate individuals' lifestyles. A better understanding of context-specific cultural settings and the linkages between the cultural and material dimensions of resource use can lead to the development of interventions that can ensure effective conservation of both natural resources and culture.
- Full Text: false
- Date Issued: 2015
- Authors: Thondhlana, Gladman , Shackleton, Sheona E
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67699 , vital:29131 , https://doi.org/10.1080/13549839.2013.818950
- Description: Publisher version , Globally, cultural values of natural resources are increasingly recognised as important for local natural resource management and conservation in and beyond parks. The tendency has been to focus on the direct-use rather than the cultural values and importance of natural resources. The cultural values underlying natural resources (directly or indirectly used) and various natural resource-based activities, and the implications for conservation, remain little explored. Drawing from household surveys, in-depth qualitative interviews, observations and secondary data, we explore the cultural significance of natural resources and different land-use practices among the San people bordering Kgalagadi Transfrontier Park in South Africa. Our findings illustrate that though cultural values are inextricably linked to resource use, they are not recognised by all community members. Further, cultural values arise from a diverse and sometimes conflicting array of values that punctuate individuals' lifestyles. A better understanding of context-specific cultural settings and the linkages between the cultural and material dimensions of resource use can lead to the development of interventions that can ensure effective conservation of both natural resources and culture.
- Full Text: false
- Date Issued: 2015
Cyber Vulnerability Assessment: Case Study of Malawi and Tanzania
- Chindipha, Stones, D, Irwin, Barry V W
- Authors: Chindipha, Stones, D , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428558 , vital:72520 , https://accconference.mandela.ac.za/ACCConference/media/Store/images/Proceedings-2015.pdf#page=105
- Description: Much as the Internet is beneficial to our daily activities, with each passing day it also brings along with it information security concerns for the users be they at company or national level. Each year the number of Internet users keeps growing, particularly in Africa, and this means only one thing, more cyber-attacks. Governments have become a focal point of this data leakage problem making this a matter of national security. Looking at the current state of affairs, cyber-based incidents are more likely to increase in Africa, mainly due to the increased prevalence and affordability of broadband connectivity which is coupled with lack of online security awareness. A drop in the cost of broadband connection means more people will be able to afford Internet connectivity. With open Source Intelligence (OSINT), this paper aims to perform a vulnerability analysis for states in Eastern Africa building from prior research by Swart et al. which showed that there are vulnerabilities in the information systems, using the case of South Africa as an example. States in East Africa are to be considered as candidates, with the final decision being determined by access to suitable resources, and availability of information. A comparative analysis to assess the factors that affect the degree of security susceptibilities in various states will also be made and information security measures used by various governments to ascertain the extent of their contribution to this vulnerability will be assessed. This pilot study will be extended to other Southern and Eastern African states like Botswana, Kenya, Uganda and Namibia in future work.
- Full Text:
- Date Issued: 2015
- Authors: Chindipha, Stones, D , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428558 , vital:72520 , https://accconference.mandela.ac.za/ACCConference/media/Store/images/Proceedings-2015.pdf#page=105
- Description: Much as the Internet is beneficial to our daily activities, with each passing day it also brings along with it information security concerns for the users be they at company or national level. Each year the number of Internet users keeps growing, particularly in Africa, and this means only one thing, more cyber-attacks. Governments have become a focal point of this data leakage problem making this a matter of national security. Looking at the current state of affairs, cyber-based incidents are more likely to increase in Africa, mainly due to the increased prevalence and affordability of broadband connectivity which is coupled with lack of online security awareness. A drop in the cost of broadband connection means more people will be able to afford Internet connectivity. With open Source Intelligence (OSINT), this paper aims to perform a vulnerability analysis for states in Eastern Africa building from prior research by Swart et al. which showed that there are vulnerabilities in the information systems, using the case of South Africa as an example. States in East Africa are to be considered as candidates, with the final decision being determined by access to suitable resources, and availability of information. A comparative analysis to assess the factors that affect the degree of security susceptibilities in various states will also be made and information security measures used by various governments to ascertain the extent of their contribution to this vulnerability will be assessed. This pilot study will be extended to other Southern and Eastern African states like Botswana, Kenya, Uganda and Namibia in future work.
- Full Text:
- Date Issued: 2015
Data Centre vulnerabilities physical, logical and trusted entity security
- Swart, Ignus, Grobler, Marthie, Irwin, Barry V W
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427859 , vital:72467 , https://www.researchgate.net/profile/Ignus-Swart/publication/305442546_Data_Centre_vulnerabilities_physical_logical_trusted_entity_security/links/578f38c108aecbca4cada6bf/Data-Centre-vulnerabilities-physical-logical-trusted-entity-security.pdf
- Description: Data centres are often the hub for a significant number of disparate interconnecting systems. With rapid advances in virtualization, the use of data centres have increased significantly and are set to continue growing. Systems hosted typically serve the data needs for a growing number of organizations ranging from private individuals to mammoth governmental departments. Due to this centralized method of operation, data centres have become a prime target for attackers. These attackers are not only after the data contained in the data centre but often the physical infrastructure the systems run on is the target of attack. Down time resulting from such an attack can affect a wide range of entities and can have severe financial implications for the owners of the data centre. To limit liability strict adherence to standards are prescribed. Technology however develops at a far faster pace than standards and our ability to accurately measure information security has significant hidden caveats. This allows for a situation where the defenders dilemma is exacerbated by information overload, a significant increase in attack surface and reporting tools that show only limited views. This paper investigates the logical and physical security components of a data centre and introduces the notion of third party involvement as an increase in attack surface due to the manner in which data centres typically operate.
- Full Text:
- Date Issued: 2015
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427859 , vital:72467 , https://www.researchgate.net/profile/Ignus-Swart/publication/305442546_Data_Centre_vulnerabilities_physical_logical_trusted_entity_security/links/578f38c108aecbca4cada6bf/Data-Centre-vulnerabilities-physical-logical-trusted-entity-security.pdf
- Description: Data centres are often the hub for a significant number of disparate interconnecting systems. With rapid advances in virtualization, the use of data centres have increased significantly and are set to continue growing. Systems hosted typically serve the data needs for a growing number of organizations ranging from private individuals to mammoth governmental departments. Due to this centralized method of operation, data centres have become a prime target for attackers. These attackers are not only after the data contained in the data centre but often the physical infrastructure the systems run on is the target of attack. Down time resulting from such an attack can affect a wide range of entities and can have severe financial implications for the owners of the data centre. To limit liability strict adherence to standards are prescribed. Technology however develops at a far faster pace than standards and our ability to accurately measure information security has significant hidden caveats. This allows for a situation where the defenders dilemma is exacerbated by information overload, a significant increase in attack surface and reporting tools that show only limited views. This paper investigates the logical and physical security components of a data centre and introduces the notion of third party involvement as an increase in attack surface due to the manner in which data centres typically operate.
- Full Text:
- Date Issued: 2015
DDoS Attack Mitigation Through Control of Inherent Charge Decay of Memory Implementations
- Herbert, Alan, Irwin, Barry V W, van Heerden, Renier P
- Authors: Herbert, Alan , Irwin, Barry V W , van Heerden, Renier P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430339 , vital:72684 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: DDoS (Distributed Denial of Service) attacks over recent years have shown to be devastating on the target systems and services made publicly available over the Internet. Furthermore, the backscatter1 caused by DDoS attacks also affects the available bandwidth and responsiveness of many other hosts within the Internet. The unfortunate reality of these attacks is that the targeted party cannot fight back due to the presence of botnets and malware-driven hosts. These hosts that carry out the attack on a target are usually controlled remotely and the owner of the device is unaware of it; for this reason one cannot attack back directly as this will serve little more than to disable an innocent party. A proposed solution to these DDoS attacks is to identify a potential attacking address and ignore communication from that address for a set period of time through time stamping.
- Full Text:
- Date Issued: 2015
- Authors: Herbert, Alan , Irwin, Barry V W , van Heerden, Renier P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430339 , vital:72684 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: DDoS (Distributed Denial of Service) attacks over recent years have shown to be devastating on the target systems and services made publicly available over the Internet. Furthermore, the backscatter1 caused by DDoS attacks also affects the available bandwidth and responsiveness of many other hosts within the Internet. The unfortunate reality of these attacks is that the targeted party cannot fight back due to the presence of botnets and malware-driven hosts. These hosts that carry out the attack on a target are usually controlled remotely and the owner of the device is unaware of it; for this reason one cannot attack back directly as this will serve little more than to disable an innocent party. A proposed solution to these DDoS attacks is to identify a potential attacking address and ignore communication from that address for a set period of time through time stamping.
- Full Text:
- Date Issued: 2015
Density and regrowth of a forest restio (Ischyrolepis eleocharis) under harvest and non-harvest treatments in dune forests of Eastern Cape Province, South Africa
- Ruwanza, Sheunesu, Shackleton, Charlie M
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180828 , vital:43649 , xlink:href="https://doi.org/10.1007/s12231-015-9306-y"
- Description: Ischyrolepis eleocharis (Mast.) H.P.Linder is a perennial rush or sedge-like herb in the Restionaceae family and has been harvested for various uses from coastal forest dunes of South Africa. Around 2005, a ban on I. eleocharis harvesting in Bathurst coastal forest was instituted by provincial conservation authorities based on their unsubstantiated impression that the species population was decreasing. Here we report on the population density pre and post the harvest ban, as well as further explore the autecology of the species by assessing plant density relative to environmental factors (slope and aspect) and a controlled experiment on regrowth after harvesting at different intensities. The results show that the shoot density of both living and dead I. eleocharis increased significantly over the past eight years. This concurs with results from the harvesting experiment which showed that I. eleocharis recovered rapidly within a year of harvesting. Both aspect and slope play a key role in the distribution of I. eleocharis, with most plants found in open patches in the forest located on the summit and upper slopes of dunes facing the landward side. These results indicate that I. eleocharis is highly abundant and resilient to harvesting.
- Full Text:
- Date Issued: 2015
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180828 , vital:43649 , xlink:href="https://doi.org/10.1007/s12231-015-9306-y"
- Description: Ischyrolepis eleocharis (Mast.) H.P.Linder is a perennial rush or sedge-like herb in the Restionaceae family and has been harvested for various uses from coastal forest dunes of South Africa. Around 2005, a ban on I. eleocharis harvesting in Bathurst coastal forest was instituted by provincial conservation authorities based on their unsubstantiated impression that the species population was decreasing. Here we report on the population density pre and post the harvest ban, as well as further explore the autecology of the species by assessing plant density relative to environmental factors (slope and aspect) and a controlled experiment on regrowth after harvesting at different intensities. The results show that the shoot density of both living and dead I. eleocharis increased significantly over the past eight years. This concurs with results from the harvesting experiment which showed that I. eleocharis recovered rapidly within a year of harvesting. Both aspect and slope play a key role in the distribution of I. eleocharis, with most plants found in open patches in the forest located on the summit and upper slopes of dunes facing the landward side. These results indicate that I. eleocharis is highly abundant and resilient to harvesting.
- Full Text:
- Date Issued: 2015
Design and Fabrication of a Low Cost Traffic Manipulation Hardware Platform
- Pennefather, Sean, Irwin, Barry V W
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427873 , vital:72468 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622941_Design_and_Fabrication_of_a_Low_Cost_Traffic_Manipulation_Hardware/links/5b9a1625458515310583fc8c/Design-and-Fabrication-of-a-Low-Cost-Traffic-Manipulation-Hardware.pdf
- Description: This paper describes the design and fabrication of a dedicated hardware platform for network traffic logging and modification at a production cost of under $300. The context of the device is briefly discussed before characteristics relating to hardware development are explored. The paper concludes with three application examples to show some to the potential functionality of the platform. Testing of the device shows an average TCP throughput of 84.44 MiB/s when using the designed Ethernet modules.
- Full Text:
- Date Issued: 2015
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427873 , vital:72468 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622941_Design_and_Fabrication_of_a_Low_Cost_Traffic_Manipulation_Hardware/links/5b9a1625458515310583fc8c/Design-and-Fabrication-of-a-Low-Cost-Traffic-Manipulation-Hardware.pdf
- Description: This paper describes the design and fabrication of a dedicated hardware platform for network traffic logging and modification at a production cost of under $300. The context of the device is briefly discussed before characteristics relating to hardware development are explored. The paper concludes with three application examples to show some to the potential functionality of the platform. Testing of the device shows an average TCP throughput of 84.44 MiB/s when using the designed Ethernet modules.
- Full Text:
- Date Issued: 2015
DNA-based identification of Lepidoptera associated with citrus in South Africa
- Marsberg, Tamryn, Hill, Martin P, Moore, Sean D, Timm, A E
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, A E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
- Full Text:
- Date Issued: 2015
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, A E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
- Full Text:
- Date Issued: 2015
Dynamic mitochondrial localisation of STAT3 in the cellular adipogenesis model 3T3-L1:
- Kramer, Adam H, Edkins, Adrienne L, Hoppe, Heinrich C, Prinsloo, Earl
- Authors: Kramer, Adam H , Edkins, Adrienne L , Hoppe, Heinrich C , Prinsloo, Earl
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164885 , vital:41181 , DOI: 10.1002/jcb.25076
- Description: A mechanistic relationship exists between protein localisation, activity and cellular differentiation. Understanding the contribution of these molecular mechanisms is required for elucidation of conditions that drive development. Literature suggests non‐canonical translocation of the Signal Transducer and Activator of Transcription 3 (STAT3) to the mitochondria contributes to the regulation of the electron transport chain, cellular respiration and reactive oxygen species production. Based on this we investigated the role of mitochondrial STAT3, specifically the serine 727 phosphorylated form, in cellular differentiation using the well‐defined mouse adipogenic model 3T3-L1.
- Full Text:
- Date Issued: 2015
- Authors: Kramer, Adam H , Edkins, Adrienne L , Hoppe, Heinrich C , Prinsloo, Earl
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164885 , vital:41181 , DOI: 10.1002/jcb.25076
- Description: A mechanistic relationship exists between protein localisation, activity and cellular differentiation. Understanding the contribution of these molecular mechanisms is required for elucidation of conditions that drive development. Literature suggests non‐canonical translocation of the Signal Transducer and Activator of Transcription 3 (STAT3) to the mitochondria contributes to the regulation of the electron transport chain, cellular respiration and reactive oxygen species production. Based on this we investigated the role of mitochondrial STAT3, specifically the serine 727 phosphorylated form, in cellular differentiation using the well‐defined mouse adipogenic model 3T3-L1.
- Full Text:
- Date Issued: 2015
Editorial. Perspectives on transformations in learning and education
- Authors: Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387277 , vital:68221 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137656"
- Description: Perspectives on transformations in learning and education
- Full Text:
- Date Issued: 2015
- Authors: Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387277 , vital:68221 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137656"
- Description: Perspectives on transformations in learning and education
- Full Text:
- Date Issued: 2015
Effects of differently shaped silver nanoparticles on the photophysics of pyridylsulfanyl-substituted phthalocyanines
- D'Souza, Sarah, Mashazi, Philani N, Britton, Jonathan, Nyokong, Tebello
- Authors: D'Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193564 , vital:45348 , xlink:href="https://doi.org/10.1016/j.poly.2015.06.038"
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines.
- Full Text:
- Date Issued: 2015
- Authors: D'Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193564 , vital:45348 , xlink:href="https://doi.org/10.1016/j.poly.2015.06.038"
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines.
- Full Text:
- Date Issued: 2015
Effects of ZnO nanohexagons and nanorods on the fluorescence behavior of metallophthalocyanines
- D'Souza, Sarah, Moeno, Sharon, Nyokong, Tebello
- Authors: D'Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189741 , vital:44927 , xlink:href="https://doi.org/10.1016/j.poly.2014.09.012"
- Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis- (mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods.
- Full Text:
- Date Issued: 2015
- Authors: D'Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189741 , vital:44927 , xlink:href="https://doi.org/10.1016/j.poly.2014.09.012"
- Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis- (mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods.
- Full Text:
- Date Issued: 2015
Electrocatalytic activity of bimetallic Au–Pd nanoparticles in the presence of cobalt tetraaminophthalocyanine
- Maringa, Audacity, Mashazi, Philani N, Nyokong, Tebello
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189719 , vital:44925 , xlink:href="https://doi.org/10.1016/j.jcis.2014.10.056"
- Description: Au and Pd nanoparticles were individually or together electrodeposited on top of polymerized cobalt tetraaminophthalocyanine (poly-CoTAPc). When Pd and Au nanoparticles are co-deposited together, the electrode is denoted as Au–Pd (co-deposited)/poly-CoTAPc-GCE. X-ray photoelectron spectroscopy (XPS) was used to show the successful deposition of AuNPs, PdNPs and Au–Pd (co-deposited). The scanning electrochemical microscopy showed that Au–Pd (co-deposited)/poly-CoTAPc-GCE (with current range of 9.5–13.5 lA) was more conducting than Au–Pd (co-deposited)-GCE (with current range of 8–12 lA). Electrochemical impedance spectroscopy (EIS) showed that there was less resistance to charge transfer for Au–Pd (co-deposited)/poly-CoTAPc-GCE compared to the rest of the electrodes. Au–Pd (co-deposited)/poly-CoTAPc-GCE showed the best activity for the electrooxidation of hydrazine in terms of limit of detection (0.5 lM), hence shows promise as an electrocatalyst for electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2015
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189719 , vital:44925 , xlink:href="https://doi.org/10.1016/j.jcis.2014.10.056"
- Description: Au and Pd nanoparticles were individually or together electrodeposited on top of polymerized cobalt tetraaminophthalocyanine (poly-CoTAPc). When Pd and Au nanoparticles are co-deposited together, the electrode is denoted as Au–Pd (co-deposited)/poly-CoTAPc-GCE. X-ray photoelectron spectroscopy (XPS) was used to show the successful deposition of AuNPs, PdNPs and Au–Pd (co-deposited). The scanning electrochemical microscopy showed that Au–Pd (co-deposited)/poly-CoTAPc-GCE (with current range of 9.5–13.5 lA) was more conducting than Au–Pd (co-deposited)-GCE (with current range of 8–12 lA). Electrochemical impedance spectroscopy (EIS) showed that there was less resistance to charge transfer for Au–Pd (co-deposited)/poly-CoTAPc-GCE compared to the rest of the electrodes. Au–Pd (co-deposited)/poly-CoTAPc-GCE showed the best activity for the electrooxidation of hydrazine in terms of limit of detection (0.5 lM), hence shows promise as an electrocatalyst for electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2015
Electrocatalytic studies of covalently immobilized metal tetra-amino phthalocyanines onto derivatized screen-printed gold electrodes
- Mashazi, Philani N, Nyokong, Tebello
- Authors: Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249059 , vital:51774 , xlink:href="https://doi.org/10.1007/s00604-010-0438-6"
- Description: Metal tetra-amino phthalocyanine complexes (MTAPc; where M is Co or Mn) were immobilized on screen-printed gold electrodes pre-modified with monolayers of benzylamino groups. The functionalized electrodes were then activated using benzene-1,4-dicarbaldehyde as a linker before MTAPc complexes were immobilized. The surface coverages for the modified electrodes confirmed the perpendicular orientation of the MTAPcs. The apparent electron transfer constant (kapp) for the electrodes is 2.2 × 10−5 cm.s−1 for both CoTAPc and MnTAPc modified electrodes as calculated with data from impedance measurements. The kapp values for the bare and benzylamino modified electrodes were found to be 1.2 × 10−4 cm.s−1 and 4.9 × 10−6 cm.s−1, respectively. The electrocatalysis of the modified electrodes towards detection of H2O2 gave significant peak current densities and electrocatalytic potentials at −0.28 V and −0.31 V for the MnTAPc and CoTAPc modified electrodes, respectively.
- Full Text:
- Date Issued: 2015
- Authors: Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249059 , vital:51774 , xlink:href="https://doi.org/10.1007/s00604-010-0438-6"
- Description: Metal tetra-amino phthalocyanine complexes (MTAPc; where M is Co or Mn) were immobilized on screen-printed gold electrodes pre-modified with monolayers of benzylamino groups. The functionalized electrodes were then activated using benzene-1,4-dicarbaldehyde as a linker before MTAPc complexes were immobilized. The surface coverages for the modified electrodes confirmed the perpendicular orientation of the MTAPcs. The apparent electron transfer constant (kapp) for the electrodes is 2.2 × 10−5 cm.s−1 for both CoTAPc and MnTAPc modified electrodes as calculated with data from impedance measurements. The kapp values for the bare and benzylamino modified electrodes were found to be 1.2 × 10−4 cm.s−1 and 4.9 × 10−6 cm.s−1, respectively. The electrocatalysis of the modified electrodes towards detection of H2O2 gave significant peak current densities and electrocatalytic potentials at −0.28 V and −0.31 V for the MnTAPc and CoTAPc modified electrodes, respectively.
- Full Text:
- Date Issued: 2015