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
Comparative photophysicochemical behavior of nanoconjugates of indium tetracarboxyphenoxy phthalocyanines covalently linked to CdTe/ZnSe/ZnO quantum dots
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7294 , http://hdl.handle.net/10962/d1020357 , http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Description: This work reports on the photophysicochemical behavior of different nanoconjugates of core/shell/shell (GSH-CdTe/ZnSe/ZnO), core/shell (GSH-CdTe/ZnSe) and core (GSH-CdTe) (quantum dots QDs) with indium tetracarboxyphenoxy phthalocyanines ((OH)InTCPPc) in dimethylsulfoxide. The fluorescence quantum yields (Φf) and lifetimes (τf, in brackets) of QDs ranged from 0.20 (13.9 ns) to 0.42 (25.6 ns). The highest Φf value was obtained for GSH-CdTe/ZnSe/ZnO (4.5) while the least was observed in GSH-CdTe/ZnSe/ZnO (7.6), the numbers in brackets refer to the sizes. For (OH)InTCPPc alone a Φf and τf values of 0.02 and 2.43 ns, respectively were obtained. In the nanoconjugates, pivotal decrease in the Φf and τf of the QDs were observed with increase in the triplet and singlet oxygen quantum yields of (OH)InTCPPc. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Full Text: false
- Date Issued: 2015
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7294 , http://hdl.handle.net/10962/d1020357 , http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Description: This work reports on the photophysicochemical behavior of different nanoconjugates of core/shell/shell (GSH-CdTe/ZnSe/ZnO), core/shell (GSH-CdTe/ZnSe) and core (GSH-CdTe) (quantum dots QDs) with indium tetracarboxyphenoxy phthalocyanines ((OH)InTCPPc) in dimethylsulfoxide. The fluorescence quantum yields (Φf) and lifetimes (τf, in brackets) of QDs ranged from 0.20 (13.9 ns) to 0.42 (25.6 ns). The highest Φf value was obtained for GSH-CdTe/ZnSe/ZnO (4.5) while the least was observed in GSH-CdTe/ZnSe/ZnO (7.6), the numbers in brackets refer to the sizes. For (OH)InTCPPc alone a Φf and τf values of 0.02 and 2.43 ns, respectively were obtained. In the nanoconjugates, pivotal decrease in the Φf and τf of the QDs were observed with increase in the triplet and singlet oxygen quantum yields of (OH)InTCPPc. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Full Text: false
- Date Issued: 2015
Comparison between Endothelin, Nitric Oxide and their Association to Blood Pressure and Body Composition in HIV Patients, in Mthatha
- Authors: Zono, Sinethemba
- Date: 2015
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2909 , vital:43105
- Description: Background: Dysfunction of the vascular endothelium is an early finding in the progression of cardiovascular disease and is closely related to clinical events in patients with obesity and hypertension. Vascular function is mediated by nitric oxide (NO) and endothelin (ET-1) which serve as natural counterparts. The aim of the study was to determine the physiological effects of HIV infection, blood pressure and body composition on the changes of ET-1 and NO and association between ET-1 and NO. Methods and results: This was a descriptive and comparative study. A Quota sample method was used. The study population consisted of 154 participants categorized into the following groups: 57 HIV negative participants (A), 40 HIV positive not on treatment participants and 57 HIV positive on treatment participants. Enzyme immunoassay kit was used for the quantitative determination of ET-1 and Nitrate/nitrite colorimetric assay kit was used for the determination of NO. Anthropometric measurements, body composition were determined. Hemodynamic measurements were also taken into account. Results: Resting metabolism, waist circumference (WC) and hip circumference had low mean levels in both HIV positives groups compared to HIV negative group. On lipid profiles visceral fat (VF), whole fat (WF) had low mean levels but skeletal muscle fat (SMF) showed the highest mean levels in both HIV positive groups. All the blood pressures between HIV groups were on a normal range scale. Mean values of endothelin and nitric oxide are increased in HIV positive not on ART and HIV (+) on ART compared with the HIV negative group. Conclusion: NO, ET-1, ART and HIV itself were associated with the pathogenesis of endothelial dysfunction in persons with HIV infection. Elevated endothelial markers namely ET-1 and NO can lead to improvement of endothelium dependent relaxation to some extent but not completely. Although these markers have deleterious effect on the endothelium but can also serve as up-regulator of hypertension. Key words: HIV-infection, antiretroviral therapy, endothelial dysfunction, Endothelin1 (ET-1), nitric oxide (NO), blood pressures (BPs). , Thesis (MSc) -- Faculty of Health Sciences, 2015
- Full Text:
- Date Issued: 2015
- Authors: Zono, Sinethemba
- Date: 2015
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2909 , vital:43105
- Description: Background: Dysfunction of the vascular endothelium is an early finding in the progression of cardiovascular disease and is closely related to clinical events in patients with obesity and hypertension. Vascular function is mediated by nitric oxide (NO) and endothelin (ET-1) which serve as natural counterparts. The aim of the study was to determine the physiological effects of HIV infection, blood pressure and body composition on the changes of ET-1 and NO and association between ET-1 and NO. Methods and results: This was a descriptive and comparative study. A Quota sample method was used. The study population consisted of 154 participants categorized into the following groups: 57 HIV negative participants (A), 40 HIV positive not on treatment participants and 57 HIV positive on treatment participants. Enzyme immunoassay kit was used for the quantitative determination of ET-1 and Nitrate/nitrite colorimetric assay kit was used for the determination of NO. Anthropometric measurements, body composition were determined. Hemodynamic measurements were also taken into account. Results: Resting metabolism, waist circumference (WC) and hip circumference had low mean levels in both HIV positives groups compared to HIV negative group. On lipid profiles visceral fat (VF), whole fat (WF) had low mean levels but skeletal muscle fat (SMF) showed the highest mean levels in both HIV positive groups. All the blood pressures between HIV groups were on a normal range scale. Mean values of endothelin and nitric oxide are increased in HIV positive not on ART and HIV (+) on ART compared with the HIV negative group. Conclusion: NO, ET-1, ART and HIV itself were associated with the pathogenesis of endothelial dysfunction in persons with HIV infection. Elevated endothelial markers namely ET-1 and NO can lead to improvement of endothelium dependent relaxation to some extent but not completely. Although these markers have deleterious effect on the endothelium but can also serve as up-regulator of hypertension. Key words: HIV-infection, antiretroviral therapy, endothelial dysfunction, Endothelin1 (ET-1), nitric oxide (NO), blood pressures (BPs). , Thesis (MSc) -- Faculty of Health Sciences, 2015
- 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
Contributions to the study of a class of optimal control problems on the orthogonal groups SO(3) and SO(4)
- Authors: Adams, Ross Montague
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64826 , vital:28608
- Description: In this thesis we investigate a class of invariant optimal control problems, and their associated quadratic Hamilton-Poisson systems, on the orthogonal groups SO(3) and SO(4). Specifically, we are concerned with the class of left-invariant control affine systems. We begin by classifying all cost-extended systems on SO(3) under cost equivalence. (Cost-extended systems are closely related to optimal control problems.) A classification of all quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space so(3)*, under affine equivalence, is also obtained. For the normal forms obtained in our classification (of Hamilton-Poisson systems) we investigate the (Lyapunov) stability nature of the equilibria using spectral and energy-Casimir methods. For a subclass of these systems, we obtain analytic expressions for the integral curves of the associated Hamiltonian vector fields in terms of (basic) Jacobi elliptic functions. The explicit relationship between the classification of cost-extended systems on SO(3) and the classification of quadratic Hamilton- Poisson systems on so(3)* is provided. On SO(4), a classification of all left-invariant control affine systems under L-equivalence is obtained. We then determine which of these representatives are controllable, thus obtaining a classification under detached feedback equivalence. We also obtain a partial classification of quadratic Hamilton-Poisson systems on the Lie-Poisson space so(4)*. An investigation of the stability nature of the equilibria for a subclass of these systems is also done. Several illustrative examples of optimal control problems on the orthogonal group SO(3) are provided. More specifically, we consider an optimal control problem corresponding to a representative of our classification (of cost-extended system) for each possible number of control inputs. For each of these problems, we obtain explicit expressions for the extremal trajectories on the homogeneous space S2 by projecting the extremal trajectories on the group SO(3). The examples provided show how our classifications of cost-extended systems and Hamilton-Poisson systems can be used to obtain the optimal controls and the extremal trajectories corresponding to a large class of optimal control problems on SO(3). An example of a four-input optimal control problem on SO(4) is also provided. This example is provided to show how the solutions of certain problems on SO(4) can be related to the solutions of certain optimal control problems on SO(3).
- Full Text:
- Date Issued: 2015
- Authors: Adams, Ross Montague
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64826 , vital:28608
- Description: In this thesis we investigate a class of invariant optimal control problems, and their associated quadratic Hamilton-Poisson systems, on the orthogonal groups SO(3) and SO(4). Specifically, we are concerned with the class of left-invariant control affine systems. We begin by classifying all cost-extended systems on SO(3) under cost equivalence. (Cost-extended systems are closely related to optimal control problems.) A classification of all quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space so(3)*, under affine equivalence, is also obtained. For the normal forms obtained in our classification (of Hamilton-Poisson systems) we investigate the (Lyapunov) stability nature of the equilibria using spectral and energy-Casimir methods. For a subclass of these systems, we obtain analytic expressions for the integral curves of the associated Hamiltonian vector fields in terms of (basic) Jacobi elliptic functions. The explicit relationship between the classification of cost-extended systems on SO(3) and the classification of quadratic Hamilton- Poisson systems on so(3)* is provided. On SO(4), a classification of all left-invariant control affine systems under L-equivalence is obtained. We then determine which of these representatives are controllable, thus obtaining a classification under detached feedback equivalence. We also obtain a partial classification of quadratic Hamilton-Poisson systems on the Lie-Poisson space so(4)*. An investigation of the stability nature of the equilibria for a subclass of these systems is also done. Several illustrative examples of optimal control problems on the orthogonal group SO(3) are provided. More specifically, we consider an optimal control problem corresponding to a representative of our classification (of cost-extended system) for each possible number of control inputs. For each of these problems, we obtain explicit expressions for the extremal trajectories on the homogeneous space S2 by projecting the extremal trajectories on the group SO(3). The examples provided show how our classifications of cost-extended systems and Hamilton-Poisson systems can be used to obtain the optimal controls and the extremal trajectories corresponding to a large class of optimal control problems on SO(3). An example of a four-input optimal control problem on SO(4) is also provided. This example is provided to show how the solutions of certain problems on SO(4) can be related to the solutions of certain optimal control problems on SO(3).
- 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
Determinants of student satisfaction with campus residence life at a South African university
- Botha, Ferdi, Snowball, Jeanette D, De Klerk, Vivian A, Radloff, Sarah E
- Authors: Botha, Ferdi , Snowball, Jeanette D , De Klerk, Vivian A , Radloff, Sarah E
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69277 , vital:29475 , https://doi.org/10.1007/978-3-319-15904-1_2
- Description: Factors outside the classroom can contribute to academic success as well as the achievement of important outcomes such as the appreciation of human diversity. Striving towards equality of residence life satisfaction is thus important for academic outcomes and for the development of well-functioning citizens. This study is based on the 2011 Quality of Residence Life (QoRL) Survey, conducted at a South African university, comprising roughly 2,000 respondents. The study investigates the association between satisfaction with QoRL and (i) residence milieu and characteristics, (ii) direct and indirect discrimination, (iii) perceptions of drug and alcohol issues in residence, (iv) safety, and (v) individual student characteristics. One main finding is that there are no significant differences in satisfaction with QoRL across racial and gender groups; suggesting significant progress in university transformation and equity goals. The general atmosphere and characteristics of residences are also important predictors of QoRL satisfaction.
- Full Text: false
- Date Issued: 2015
- Authors: Botha, Ferdi , Snowball, Jeanette D , De Klerk, Vivian A , Radloff, Sarah E
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69277 , vital:29475 , https://doi.org/10.1007/978-3-319-15904-1_2
- Description: Factors outside the classroom can contribute to academic success as well as the achievement of important outcomes such as the appreciation of human diversity. Striving towards equality of residence life satisfaction is thus important for academic outcomes and for the development of well-functioning citizens. This study is based on the 2011 Quality of Residence Life (QoRL) Survey, conducted at a South African university, comprising roughly 2,000 respondents. The study investigates the association between satisfaction with QoRL and (i) residence milieu and characteristics, (ii) direct and indirect discrimination, (iii) perceptions of drug and alcohol issues in residence, (iv) safety, and (v) individual student characteristics. One main finding is that there are no significant differences in satisfaction with QoRL across racial and gender groups; suggesting significant progress in university transformation and equity goals. The general atmosphere and characteristics of residences are also important predictors of QoRL satisfaction.
- Full Text: false
- Date Issued: 2015
Detriments associated with substance abuse among out - of - school youth in Ntselamanzi, village, Alice Town
- Authors: Chatikobo, Nyasha
- Date: 2015
- Subjects: Substance abuse--South Africa--Eastern Cape , Drug abuse--South Africa--Eastern Cape , Youth--Substance use--South Africa--Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19442 , vital:43087
- Description: The main aim of the study was to investigate the detriments associated with substance abuse among the out- of- school youth of Ntselamanzi Village in Alice. This study intended to achieve the following objectives. (i) to establish the causes of increased indulgence in substance abuse in Ntselamanzi village, Eastern Cape. (ii) to identify the various kinds of drugs abused by the society of Ntselamanzi (iii) to identify the consequences of substance abuse to the lives of the out-of-school youth. (iv) to suggest the strategies that can be used to reduce substance abuse in order to enhance the youth‟s socio-economic growth and societal bliss. Using the quantitative method ninety-eight questionnaires were administered to the out-of-school youth in Ntselamanzi village and eighty questionnaires were returned fully answered. The major findings of the study outlined that dominating factors of substance abuse in Ntselamanzi village were family drug use, increased drug accessibility, lack of recreation and peer influence. As a result drug abuse among the out of school youth has indicated that the youth end up dropping out of school, unemployed, facing health complications and committing anti-social activities in the village which causing family conflicts and rifts in the community. These all affected the out-of-school youths‟ well-being, academic future and their quality of life was lowered due to all related issues with drug abuse. It can be concluded that drug use among rural outof-school youth is detrimental to the out-of-school youths, their families destroyed and their community crippled from the anti-social activities that take place. The future of the youths‟ education is hampered; the quality of persons in the community and families is lowered. Having unproductive out-of-school youth as a result of drug abuse is not good for the development of the village and all the persons therein. , Thesis (M Soc Sc) (Social Work) -- University of Fort Hare, 2015
- Full Text:
- Date Issued: 2015
- Authors: Chatikobo, Nyasha
- Date: 2015
- Subjects: Substance abuse--South Africa--Eastern Cape , Drug abuse--South Africa--Eastern Cape , Youth--Substance use--South Africa--Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19442 , vital:43087
- Description: The main aim of the study was to investigate the detriments associated with substance abuse among the out- of- school youth of Ntselamanzi Village in Alice. This study intended to achieve the following objectives. (i) to establish the causes of increased indulgence in substance abuse in Ntselamanzi village, Eastern Cape. (ii) to identify the various kinds of drugs abused by the society of Ntselamanzi (iii) to identify the consequences of substance abuse to the lives of the out-of-school youth. (iv) to suggest the strategies that can be used to reduce substance abuse in order to enhance the youth‟s socio-economic growth and societal bliss. Using the quantitative method ninety-eight questionnaires were administered to the out-of-school youth in Ntselamanzi village and eighty questionnaires were returned fully answered. The major findings of the study outlined that dominating factors of substance abuse in Ntselamanzi village were family drug use, increased drug accessibility, lack of recreation and peer influence. As a result drug abuse among the out of school youth has indicated that the youth end up dropping out of school, unemployed, facing health complications and committing anti-social activities in the village which causing family conflicts and rifts in the community. These all affected the out-of-school youths‟ well-being, academic future and their quality of life was lowered due to all related issues with drug abuse. It can be concluded that drug use among rural outof-school youth is detrimental to the out-of-school youths, their families destroyed and their community crippled from the anti-social activities that take place. The future of the youths‟ education is hampered; the quality of persons in the community and families is lowered. Having unproductive out-of-school youth as a result of drug abuse is not good for the development of the village and all the persons therein. , Thesis (M Soc Sc) (Social Work) -- University of Fort Hare, 2015
- Full Text:
- Date Issued: 2015
Development and manufacture of sustained release captopril beads
- Authors: Mhaka, Farai Arthur
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54712 , vital:26602
- Description: Hypertension has a high mortality rate in developing countries such as South Africa. Although the prevention and control of hypertension is a health priority, efforts to decrease the global burden of hypertension and improve control over the condition are inadequate. The use of angiotensin converting enzyme (ACE) inhibitors such as captopril (CPT) have been effective for the management of hypertension when used as first line therapy alone or in combination. Commercially available immediate release dosage forms containing 12.5, 25 and 50 mg of CPT are administered two or three times a day to treat hypertension. CPT degrades in aqueous media with the sulfhydryl functional moiety responsible for adverse effects such as hypersensitivity, taste disturbances and/or presenting with a dry hacking cough. CPT has a short elimination half-life of between 1.6 and 1.9 hours, which means that the compound is a suitable candidate for inclusion in sustained release (SR) dosage forms. Manufacturing a SR dosage form of coated beads for twice daily dosing may reduce the incidence and intensity of undesirable adverse effects, improve the stability of CPT and improve patient adherence. A stability indicating reversed-phase high performance liquid chromatographic (RP-HPLC) method was developed and optimised using a central composite design approach. As part of this approach the interactive effects of input factors, viz. pH, methanol (MeOH) content and column temperature on retention time, were investigated to achieve a separation with well-resolved and symmetrical peaks for CPT and salicylic acid. The method was validated using ICH guidelines and was found to be simple, linear, precise, accurate, selective and rapid for the in vitro quantitation of CPT. The method was successfully applied for the analysis of both commercially available and test formulations. Preformulation studies were undertaken to establish the physical and chemical properties of CPT, excipients and dosage forms to ensure the production of stabile and bioavailable products. Powder blends were assessed for flow properties using angle of repose (AOR), and bulk and tapped density, which were subsequently used to calculate Carr’s Index (CI) and the Hausner ratio (HR). The addition of talc resulted in the most powder blends with AOR, CI and HR that were within a range indicative of satisfactory to good flow properties. The use of talc was necessary to ensure that blending prior to wet granulation and extrusion-spheronisation would produce homogenous powders. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were used for the identification and purity of CPT alone and 1:1 binary mixtures with excipients in an effort to establish if CPT was likely to undergo physical and/or chemical modification during production. The DSC thermograms for all CPT-excipient mixtures revealed the presence of a melting endotherm that was wider, occurring at 110.93 °C (Tpeak for pure CPT). The characteristic peaks for specific functional groups were present in the FT-IR spectra for powder mixtures, indicating the absence of incompatibilities. Dialysis studies were used to investigate if the ammonium oleate present in Surelease® E-7-19010 interacted with CPT. The results suggests that an interaction between CPT and Surelease® E-7-19010 during processing of CPT beads was unlikely to occur. Preliminary investigations reveal that Methocel® K100M, Methocel® E4M, Avicel® PH102, Eudragit® RS PO, Surelease® E-7-19010 and talc are compatible with CPT and could be used for the manufacture of SR CPT beads. CPT beads were manufactured using extrusion-spheronisation and coated using a fluidised bed drier fitted with a Wurster insert. The amount of granulating fluid, coating levels, curing time and formulation composition were varied to achieve CPT release with specific criteria to develop a preliminary formulation. The coated beads met all desired quality attributes in respect of micromeritic and flow properties, content uniformity and friability. Response Surface Methodology was used to further optimise the SR CPT formulation. The Plackett-Burman design was used for this process to produce an SR dosage form with desirable quality attributes achieved by altering formulation composition, extrusion-spheronisation variables and coating parameters. ANOVA data revealed significant responses for yield, aspect ratio, sphericity, coating efficiency and cumulative percent CPT released at 2 and 12 hours. Formulations in which the high molecular weight HPMC were used in increased concentrations resulted in the formation of a sticky wet mass and extrudate, resulting in a decrease in yield. The application of a permeable, but insoluble Surelease® coat onto the surface of the beads formed a barrier that complements the activity of the hydrophilic matrix in preventing rapid dissolution and retarding the release of CPT from the beads. The amount of CPT released over 12 hours revealed that increasing the Methocel® K100M content entrapped CPT and retained it more efficiently in the hydrated matrix, resulting in a slow rate of CPT release. In vitro release data were fitted to a number of models in an attempt to elucidate mechanistic aspects of transport processes specific to CPT from the coated bead formulations. The results of fitting data from optimised batches revealed that the goodness of fit based on the adjusted correlation coefficient ranged between 0.953 and 0.976 for the Higuchi model, indicating that diffusion is a predominant factor that controls CPT release from the coated beads. The results of fitting data to the Korsmeyer-Peppas model suggest that the mechanism of CPT release includes transport of the dissolution medium from the vessel reservoir into the core of the bead due to osmotic potential, dissolution of CPT, mass transfer of the dissolved CPT within the core, partitioning between the solution and polymeric film, mass transfer of dissolved CPT through the film to ultimately reach the bulk dissolution fluid. A SR CPT bead formulation that has potential for further development and optimisation for scaled-up production using RSM approaches and Design of Experiments such as CCD or Box-Behnken has been successfully developed and manufactured using extrusion, spheronisation and coating processes. Assessment of all batches of beads manufactured exhibited satisfactory to good flow properties and demonstrated SR profiles over 12 hours that met USP criteria for SR dosage forms.
- Full Text:
- Date Issued: 2015
- Authors: Mhaka, Farai Arthur
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54712 , vital:26602
- Description: Hypertension has a high mortality rate in developing countries such as South Africa. Although the prevention and control of hypertension is a health priority, efforts to decrease the global burden of hypertension and improve control over the condition are inadequate. The use of angiotensin converting enzyme (ACE) inhibitors such as captopril (CPT) have been effective for the management of hypertension when used as first line therapy alone or in combination. Commercially available immediate release dosage forms containing 12.5, 25 and 50 mg of CPT are administered two or three times a day to treat hypertension. CPT degrades in aqueous media with the sulfhydryl functional moiety responsible for adverse effects such as hypersensitivity, taste disturbances and/or presenting with a dry hacking cough. CPT has a short elimination half-life of between 1.6 and 1.9 hours, which means that the compound is a suitable candidate for inclusion in sustained release (SR) dosage forms. Manufacturing a SR dosage form of coated beads for twice daily dosing may reduce the incidence and intensity of undesirable adverse effects, improve the stability of CPT and improve patient adherence. A stability indicating reversed-phase high performance liquid chromatographic (RP-HPLC) method was developed and optimised using a central composite design approach. As part of this approach the interactive effects of input factors, viz. pH, methanol (MeOH) content and column temperature on retention time, were investigated to achieve a separation with well-resolved and symmetrical peaks for CPT and salicylic acid. The method was validated using ICH guidelines and was found to be simple, linear, precise, accurate, selective and rapid for the in vitro quantitation of CPT. The method was successfully applied for the analysis of both commercially available and test formulations. Preformulation studies were undertaken to establish the physical and chemical properties of CPT, excipients and dosage forms to ensure the production of stabile and bioavailable products. Powder blends were assessed for flow properties using angle of repose (AOR), and bulk and tapped density, which were subsequently used to calculate Carr’s Index (CI) and the Hausner ratio (HR). The addition of talc resulted in the most powder blends with AOR, CI and HR that were within a range indicative of satisfactory to good flow properties. The use of talc was necessary to ensure that blending prior to wet granulation and extrusion-spheronisation would produce homogenous powders. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were used for the identification and purity of CPT alone and 1:1 binary mixtures with excipients in an effort to establish if CPT was likely to undergo physical and/or chemical modification during production. The DSC thermograms for all CPT-excipient mixtures revealed the presence of a melting endotherm that was wider, occurring at 110.93 °C (Tpeak for pure CPT). The characteristic peaks for specific functional groups were present in the FT-IR spectra for powder mixtures, indicating the absence of incompatibilities. Dialysis studies were used to investigate if the ammonium oleate present in Surelease® E-7-19010 interacted with CPT. The results suggests that an interaction between CPT and Surelease® E-7-19010 during processing of CPT beads was unlikely to occur. Preliminary investigations reveal that Methocel® K100M, Methocel® E4M, Avicel® PH102, Eudragit® RS PO, Surelease® E-7-19010 and talc are compatible with CPT and could be used for the manufacture of SR CPT beads. CPT beads were manufactured using extrusion-spheronisation and coated using a fluidised bed drier fitted with a Wurster insert. The amount of granulating fluid, coating levels, curing time and formulation composition were varied to achieve CPT release with specific criteria to develop a preliminary formulation. The coated beads met all desired quality attributes in respect of micromeritic and flow properties, content uniformity and friability. Response Surface Methodology was used to further optimise the SR CPT formulation. The Plackett-Burman design was used for this process to produce an SR dosage form with desirable quality attributes achieved by altering formulation composition, extrusion-spheronisation variables and coating parameters. ANOVA data revealed significant responses for yield, aspect ratio, sphericity, coating efficiency and cumulative percent CPT released at 2 and 12 hours. Formulations in which the high molecular weight HPMC were used in increased concentrations resulted in the formation of a sticky wet mass and extrudate, resulting in a decrease in yield. The application of a permeable, but insoluble Surelease® coat onto the surface of the beads formed a barrier that complements the activity of the hydrophilic matrix in preventing rapid dissolution and retarding the release of CPT from the beads. The amount of CPT released over 12 hours revealed that increasing the Methocel® K100M content entrapped CPT and retained it more efficiently in the hydrated matrix, resulting in a slow rate of CPT release. In vitro release data were fitted to a number of models in an attempt to elucidate mechanistic aspects of transport processes specific to CPT from the coated bead formulations. The results of fitting data from optimised batches revealed that the goodness of fit based on the adjusted correlation coefficient ranged between 0.953 and 0.976 for the Higuchi model, indicating that diffusion is a predominant factor that controls CPT release from the coated beads. The results of fitting data to the Korsmeyer-Peppas model suggest that the mechanism of CPT release includes transport of the dissolution medium from the vessel reservoir into the core of the bead due to osmotic potential, dissolution of CPT, mass transfer of the dissolved CPT within the core, partitioning between the solution and polymeric film, mass transfer of dissolved CPT through the film to ultimately reach the bulk dissolution fluid. A SR CPT bead formulation that has potential for further development and optimisation for scaled-up production using RSM approaches and Design of Experiments such as CCD or Box-Behnken has been successfully developed and manufactured using extrusion, spheronisation and coating processes. Assessment of all batches of beads manufactured exhibited satisfactory to good flow properties and demonstrated SR profiles over 12 hours that met USP criteria for SR dosage forms.
- 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