An Assessment of the Effect of Rotenone on Selected Non-Target Aquatic Fauna
- Dalu, Tatenda, Wasserman, Ryan J, Jordaan, Martine, Froneman, P William, Froneman, Pierre William, Weyl, Olaf L F
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Jordaan, Martine , Froneman, P William , Froneman, Pierre William , Weyl, Olaf L F
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124240 , vital:35579 , https://doi.org/10.1371/journal.pone.0142140.g001
- Description: Rotenone, a naturally occurring ketone, is widely employed for the management of invasive fish species. The use of rotenone poses serious challenges to conservation practitioners due to its impacts on non-target organisms including amphibians and macroinvertebrates. Using laboratory studies, we investigated the effects of different rotenone concentrations (0, 12.5, 25, 37.5, 50, 100 μg L-1) on selected invertebrate groups; Aeshnidae, Belostomatids, Decapods, Ephemeroptera, Pulmonata and zooplankton over a period of 18 hours. Based on field observations and body size, we hypothesized that Ephemeropterans and zooplank- ton would be more susceptible to rote none than Decapods, Belostomatids and snails. Experimental results supported this hypothesis and mortality and behaviour effects varied considerably between taxa, ranging from no effect (crab Potamonuates sidneyi) to 100% mortality (Daphnia pulex and Paradiaptomus lamellatus). Planktonic invertebrates were par- ticularly sensitive to rotenone even at very low concentrations. Future research should investigate the recovery time of invertebrate communities after the application of rotenone and conduct field assessments assessing the longer term effects of rotenone exposure on the population dynamics of those less sensitive organisms.
- Full Text:
- Date Issued: 2015
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Jordaan, Martine , Froneman, P William , Froneman, Pierre William , Weyl, Olaf L F
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124240 , vital:35579 , https://doi.org/10.1371/journal.pone.0142140.g001
- Description: Rotenone, a naturally occurring ketone, is widely employed for the management of invasive fish species. The use of rotenone poses serious challenges to conservation practitioners due to its impacts on non-target organisms including amphibians and macroinvertebrates. Using laboratory studies, we investigated the effects of different rotenone concentrations (0, 12.5, 25, 37.5, 50, 100 μg L-1) on selected invertebrate groups; Aeshnidae, Belostomatids, Decapods, Ephemeroptera, Pulmonata and zooplankton over a period of 18 hours. Based on field observations and body size, we hypothesized that Ephemeropterans and zooplank- ton would be more susceptible to rote none than Decapods, Belostomatids and snails. Experimental results supported this hypothesis and mortality and behaviour effects varied considerably between taxa, ranging from no effect (crab Potamonuates sidneyi) to 100% mortality (Daphnia pulex and Paradiaptomus lamellatus). Planktonic invertebrates were par- ticularly sensitive to rotenone even at very low concentrations. Future research should investigate the recovery time of invertebrate communities after the application of rotenone and conduct field assessments assessing the longer term effects of rotenone exposure on the population dynamics of those less sensitive organisms.
- Full Text:
- Date Issued: 2015
Reflections on Teaching Africa in South Africa:
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142235 , vital:38061 , DOI: 10.1111/1467-9256.12107
- Description: This article draws on the author’s experience of teaching African Studies to undergraduate South African students in order to reflect on some of the key challenges facing teachers of African Studies, both in South Africa and beyond. In particular, it discusses challenges relating to teaching a field as contested as African Studies, looking at whether teaching African alternatives to mainstream African politics is helpful and at whether and how one can teach Africa in a way that encourages and develops critical thinking. The article also explores how the racial politics of the context in which one teaches African Studies inevitably affects the way in which students engage with the content of the course. While the article discusses these issues in relation to the South African higher education context in particular, implications for other contexts are also highlighted.
- Full Text:
- Date Issued: 2016
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142235 , vital:38061 , DOI: 10.1111/1467-9256.12107
- Description: This article draws on the author’s experience of teaching African Studies to undergraduate South African students in order to reflect on some of the key challenges facing teachers of African Studies, both in South Africa and beyond. In particular, it discusses challenges relating to teaching a field as contested as African Studies, looking at whether teaching African alternatives to mainstream African politics is helpful and at whether and how one can teach Africa in a way that encourages and develops critical thinking. The article also explores how the racial politics of the context in which one teaches African Studies inevitably affects the way in which students engage with the content of the course. While the article discusses these issues in relation to the South African higher education context in particular, implications for other contexts are also highlighted.
- Full Text:
- Date Issued: 2016
LCT in mixed-methods research: evolving an instrument for quantitative data
- Maton, Karl, Howard, Sarah Katherine
- Authors: Maton, Karl , Howard, Sarah Katherine
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/66479 , vital:28954
- Description: publisher version , A mantra of social science declares a fundamental divide between the quantitative and the qualitative that involves more than methods. According to this depiction, the two methodologies are intrinsically associated with a range of ontological, epistemological, political and moral stances. Each of these constellations of stances is strongly integrated, such that choice of method is held to involve a series of associated choices. Each constellation is also strongly opposed to the other, along axes labelled positivism/constructivism, scientism/humanism, conservative/critical, old/new, among others. These ‘binary constellations’ (Maton 2014b: 148-70) offer a forced choice between two tightly-knit sets of practices that are portrayed as jointly exhaustive and mutually exclusive. So widespread is this methodological binarism that many scholars ‘are left with the impression that they have to pledge allegiance to one research school of thought or the other’ (Johnson and Onwuegbuzie 2004: 14). A competing mantra disclaims this divide. Distinctions underpinning the picture of binary constellations have been regularly dissolved. Arguments that one deals with numbers, the other with words, one studies behaviour, the other reveals meanings, one is hypothetico-deductive, the other inductive, one enables generalization, the other explores singular depth, among others, have been repeatedly undermined (e.g. Hammersley 1992). Indeed, the death of the divide is frequently declared. Calls for ‘transcending’ (Salomon 1991) or ‘getting over’ (Howe 1992) the quantitative-qualitative debate and arguments for mixed-methods research (Brannen 2005; Johnson and Onwuegbuzie 2004) are recurrent. These calls highlight how the methodologies offer complementary insights for research and demonstrate that eschewing either methodology on principle is unnecessarily renouncing potential explanatory power. However, the call to mixed-methods research remains more breached than honoured. Methodological monotheism remains dominant – studies of education and society typically adopt either quantitative or qualitative methods. As we shall discuss, the former is typically associated with the influence of psychology and the latter is often claimed as emblematic of sociology. Studies utilizing the sociological frameworks on which Legitimation Code Theory (LCT) builds have echoed this pattern by overwhelmingly adopting qualitative methods. Accordingly, Part I of this volume begins by exploring how LCT concepts can be enacted in qualitative research (Chapter 2). However, LCT is not limited to one methodology and a growing body of mixed-methods research is engaging with both qualitative and quantitative data. In this chapter we illustrate how this research works and the gains it offers. For resolutely qualitative researchers, the prospect of reading anything quantitative, even in mixed-methods research, may be unenticing. However, it would be a mistake to pass over this chapter, for several reasons. First, we offer insights into research practice that might surprise such scholars. As Bourdieu argued, ‘methodological indictments are too often no more than a disguised way of making a virtue out of necessity, of feigning to dismiss, to ignore in an active way, what one is ignorant of in fact’ (Bourdieu and Wacquant 1992: 226). Our aim is to contribute towards removing this reason for one-sidedness. We show, for example, how quantitative methods confound their common portrayal as neat, straightforward and procedural; they are complex and involved and require craft work and judgement. Our focus is, therefore, more practical than metaphysical. We shall not enter seemingly endless debates over whether the ‘quantitative-qualitative divide’ refers to paradigms, epistemologies or methods and whether these are complementary or incommensurable. Rather, we discuss the development of an instrument for enacting LCT concepts in quantitative methods and ground this account in real examples of mixed-methods research. Specifically, we trace the evolution of an instrument for embedding specialization codes within questionnaires through its creation for research into school music and then its development within studies of educational technology. Given that mathematics can be off-putting to the noviciate, we minimize discussion of statistics and explain measures in lay terms. Second, this is much more than a story of quantitative methods. The evolution of the instrument both shaped qualitative methods and was shaped by the data they generated, offering insights into how qualitative research can more fully engage with LCT. Its development also involved intimate dialogue with theory that shed fresh light on LCT itself, making explicit the ‘gaze’ embodied by the framework (Chapter 1, this volume). We shall highlight wider lessons learned about the craft of enacting LCT in research, lessons of direct relevance for studies using any methods. Third, we shall illustrate the explanatory power offered by using quantitative and qualitative methods together, such as providing a robust basis for detailed findings, identifying wider-scale trends typically inaccessible to qualitative methods that provide a context for their data, and facilitating knowledge-building through greater replicability across contexts and over time. For example, the technology studies built directly on the music studies to cumulatively develop the instrument and generated probably the largest data set in code sociology: 97,386 responses (83,937 student and 13,449 staff surveys) on the organizing principles of academic subjects, alongside 20 in-depth qualitative case studies of secondary schools. This offers a foundation of substantial breadth and depth for making claims about knowledge practices across the disciplinary map and a firm basis on which future research into disciplinary differences can build. Moreover, the quantitative instrument itself can be adopted or adapted in new studies, further enabling cumulative knowledge-building. Given these substantive, methodological and theoretical gains, it is perhaps surprising there exists any temptation to skip past discussion of mixed-methods research. This reflects the methodological character of the fields in which LCT emerged. We thus begin by briefly illustrating how the sociological frameworks on which the theory builds have become distanced from quantitative methods.
- Full Text: false
- Date Issued: 2016
- Authors: Maton, Karl , Howard, Sarah Katherine
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/66479 , vital:28954
- Description: publisher version , A mantra of social science declares a fundamental divide between the quantitative and the qualitative that involves more than methods. According to this depiction, the two methodologies are intrinsically associated with a range of ontological, epistemological, political and moral stances. Each of these constellations of stances is strongly integrated, such that choice of method is held to involve a series of associated choices. Each constellation is also strongly opposed to the other, along axes labelled positivism/constructivism, scientism/humanism, conservative/critical, old/new, among others. These ‘binary constellations’ (Maton 2014b: 148-70) offer a forced choice between two tightly-knit sets of practices that are portrayed as jointly exhaustive and mutually exclusive. So widespread is this methodological binarism that many scholars ‘are left with the impression that they have to pledge allegiance to one research school of thought or the other’ (Johnson and Onwuegbuzie 2004: 14). A competing mantra disclaims this divide. Distinctions underpinning the picture of binary constellations have been regularly dissolved. Arguments that one deals with numbers, the other with words, one studies behaviour, the other reveals meanings, one is hypothetico-deductive, the other inductive, one enables generalization, the other explores singular depth, among others, have been repeatedly undermined (e.g. Hammersley 1992). Indeed, the death of the divide is frequently declared. Calls for ‘transcending’ (Salomon 1991) or ‘getting over’ (Howe 1992) the quantitative-qualitative debate and arguments for mixed-methods research (Brannen 2005; Johnson and Onwuegbuzie 2004) are recurrent. These calls highlight how the methodologies offer complementary insights for research and demonstrate that eschewing either methodology on principle is unnecessarily renouncing potential explanatory power. However, the call to mixed-methods research remains more breached than honoured. Methodological monotheism remains dominant – studies of education and society typically adopt either quantitative or qualitative methods. As we shall discuss, the former is typically associated with the influence of psychology and the latter is often claimed as emblematic of sociology. Studies utilizing the sociological frameworks on which Legitimation Code Theory (LCT) builds have echoed this pattern by overwhelmingly adopting qualitative methods. Accordingly, Part I of this volume begins by exploring how LCT concepts can be enacted in qualitative research (Chapter 2). However, LCT is not limited to one methodology and a growing body of mixed-methods research is engaging with both qualitative and quantitative data. In this chapter we illustrate how this research works and the gains it offers. For resolutely qualitative researchers, the prospect of reading anything quantitative, even in mixed-methods research, may be unenticing. However, it would be a mistake to pass over this chapter, for several reasons. First, we offer insights into research practice that might surprise such scholars. As Bourdieu argued, ‘methodological indictments are too often no more than a disguised way of making a virtue out of necessity, of feigning to dismiss, to ignore in an active way, what one is ignorant of in fact’ (Bourdieu and Wacquant 1992: 226). Our aim is to contribute towards removing this reason for one-sidedness. We show, for example, how quantitative methods confound their common portrayal as neat, straightforward and procedural; they are complex and involved and require craft work and judgement. Our focus is, therefore, more practical than metaphysical. We shall not enter seemingly endless debates over whether the ‘quantitative-qualitative divide’ refers to paradigms, epistemologies or methods and whether these are complementary or incommensurable. Rather, we discuss the development of an instrument for enacting LCT concepts in quantitative methods and ground this account in real examples of mixed-methods research. Specifically, we trace the evolution of an instrument for embedding specialization codes within questionnaires through its creation for research into school music and then its development within studies of educational technology. Given that mathematics can be off-putting to the noviciate, we minimize discussion of statistics and explain measures in lay terms. Second, this is much more than a story of quantitative methods. The evolution of the instrument both shaped qualitative methods and was shaped by the data they generated, offering insights into how qualitative research can more fully engage with LCT. Its development also involved intimate dialogue with theory that shed fresh light on LCT itself, making explicit the ‘gaze’ embodied by the framework (Chapter 1, this volume). We shall highlight wider lessons learned about the craft of enacting LCT in research, lessons of direct relevance for studies using any methods. Third, we shall illustrate the explanatory power offered by using quantitative and qualitative methods together, such as providing a robust basis for detailed findings, identifying wider-scale trends typically inaccessible to qualitative methods that provide a context for their data, and facilitating knowledge-building through greater replicability across contexts and over time. For example, the technology studies built directly on the music studies to cumulatively develop the instrument and generated probably the largest data set in code sociology: 97,386 responses (83,937 student and 13,449 staff surveys) on the organizing principles of academic subjects, alongside 20 in-depth qualitative case studies of secondary schools. This offers a foundation of substantial breadth and depth for making claims about knowledge practices across the disciplinary map and a firm basis on which future research into disciplinary differences can build. Moreover, the quantitative instrument itself can be adopted or adapted in new studies, further enabling cumulative knowledge-building. Given these substantive, methodological and theoretical gains, it is perhaps surprising there exists any temptation to skip past discussion of mixed-methods research. This reflects the methodological character of the fields in which LCT emerged. We thus begin by briefly illustrating how the sociological frameworks on which the theory builds have become distanced from quantitative methods.
- Full Text: false
- Date Issued: 2016
Free space in the academy
- Authors: Janz, Bruce B
- Date: 2015
- Subjects: Academic Freedom -- South Africa Universities and colleges -- South Africa Equality Liberty Education and state -- South Africa Education, Higher -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/848 , vital:19996
- Description: “Academic freedom” does not mean the same thing to everyone. There are, to be sure, a few who argue against it. Sandra Korn, in the Harvard Crimson last year, argued that we should abandon academic freedom in favor of academic justice. She argues that we have reached a consensus on issues such as racism, classism and sexism, and so to promote racist or classist or sexist views under the guise of “academic freedom” is to ignore a higher standard and more importantly to ignore the fact that academic freedom is always couched in political realities, and is never the dispassionate exercise of reason and the pursuit of knowledge. It always serves an agenda, and so if that is the case, it should serve the agenda of justice, particularly justice for disadvantaged and marginalized people. Her online article, when I last looked, had almost 1300 comments, and had inspired commentary from a number of other publications. You can imagine the range of these comments and reactions: everything from “this is long overdue” to the newest favorite insult circulating the internet, “she’s just another Social Justice Warrior (SJW).”
- Full Text:
- Date Issued: 2015
- Authors: Janz, Bruce B
- Date: 2015
- Subjects: Academic Freedom -- South Africa Universities and colleges -- South Africa Equality Liberty Education and state -- South Africa Education, Higher -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/848 , vital:19996
- Description: “Academic freedom” does not mean the same thing to everyone. There are, to be sure, a few who argue against it. Sandra Korn, in the Harvard Crimson last year, argued that we should abandon academic freedom in favor of academic justice. She argues that we have reached a consensus on issues such as racism, classism and sexism, and so to promote racist or classist or sexist views under the guise of “academic freedom” is to ignore a higher standard and more importantly to ignore the fact that academic freedom is always couched in political realities, and is never the dispassionate exercise of reason and the pursuit of knowledge. It always serves an agenda, and so if that is the case, it should serve the agenda of justice, particularly justice for disadvantaged and marginalized people. Her online article, when I last looked, had almost 1300 comments, and had inspired commentary from a number of other publications. You can imagine the range of these comments and reactions: everything from “this is long overdue” to the newest favorite insult circulating the internet, “she’s just another Social Justice Warrior (SJW).”
- Full Text:
- Date Issued: 2015
Making rules to live by: Was the proposed regulatory regime for invasive species reasonable? Perceptions of the South African trout industry
- Marire, Juniours, Snowball, Jeanette D, Fraser, Gavin C G
- Authors: Marire, Juniours , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68566 , vital:29285 , http://2015.essa.org.za/fullpaper/essa_2938.pdf
- Description: Publisher version , Despite considerable economic impact of trout-based aquaculture and recreational fishing, the Department of Environmental Affairs has been focusing almost entirely on ecological criteria in deciding the regulatory regime for trout. We examined whether the proposed regulatory regime for alien and invasive species that was published by the Department of Environmental Affairs in 2014 for public comment was reasonable. The analysis produced factors that might matter in the design of reasonable institutional arrangements that impose a reasonable regulatory burden on economic sectors utilising invasive species. We conducted factor analysis using an online survey that we conducted between May and July 2014. We obtained four clusters of factors: participatory policymaking, people-centeredness, credible scientific evidence for listing species as invasive and contextualisation of international evidence. We then utilised the factors in a logistic regression framework to assess their influence on the probability of perceiving the regulations to be reasonable. The likelihood of a trout sector player perceiving the regulations to be reasonable was 1.2%. We found that a one standard deviation increase in the “credibility of scientific evidence” increased the odds of perceiving the regulations to be reasonable by 1645%. A one standard deviation increase in “participation” increased the odds of perceiving the regulations to be reasonable by 410%. A one standard deviation increase in “people-centeredness” increased the odds of perceiving the regulations to be reasonable by 600%. Lastly, a one standard deviation increase in the variable “contextualising international evidence” increased the odds of perceiving the regulations to be reasonable by 415%. This research demonstrates that properly addressing the socioeconomic aspects of new policies in addition to ecological criteria makes it far more likely that stakeholders will regard them as reasonable, even if the new policies impose increased regulatory transaction cost burden on users or reduced access to a resource.
- Full Text:
- Date Issued: 2015
- Authors: Marire, Juniours , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68566 , vital:29285 , http://2015.essa.org.za/fullpaper/essa_2938.pdf
- Description: Publisher version , Despite considerable economic impact of trout-based aquaculture and recreational fishing, the Department of Environmental Affairs has been focusing almost entirely on ecological criteria in deciding the regulatory regime for trout. We examined whether the proposed regulatory regime for alien and invasive species that was published by the Department of Environmental Affairs in 2014 for public comment was reasonable. The analysis produced factors that might matter in the design of reasonable institutional arrangements that impose a reasonable regulatory burden on economic sectors utilising invasive species. We conducted factor analysis using an online survey that we conducted between May and July 2014. We obtained four clusters of factors: participatory policymaking, people-centeredness, credible scientific evidence for listing species as invasive and contextualisation of international evidence. We then utilised the factors in a logistic regression framework to assess their influence on the probability of perceiving the regulations to be reasonable. The likelihood of a trout sector player perceiving the regulations to be reasonable was 1.2%. We found that a one standard deviation increase in the “credibility of scientific evidence” increased the odds of perceiving the regulations to be reasonable by 1645%. A one standard deviation increase in “participation” increased the odds of perceiving the regulations to be reasonable by 410%. A one standard deviation increase in “people-centeredness” increased the odds of perceiving the regulations to be reasonable by 600%. Lastly, a one standard deviation increase in the variable “contextualising international evidence” increased the odds of perceiving the regulations to be reasonable by 415%. This research demonstrates that properly addressing the socioeconomic aspects of new policies in addition to ecological criteria makes it far more likely that stakeholders will regard them as reasonable, even if the new policies impose increased regulatory transaction cost burden on users or reduced access to a resource.
- Full Text:
- Date Issued: 2015
Secrets, lies and redemption:
- Boshoff, Priscilla A, Prinsloo, Jeanne
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143381 , vital:38241 , DOI: 10.1080/00020184.2017.1285671
- Description: Confession is a central disciplining technology deployed in the second series of Intersexions, a popular South African TV series that seeks to change sexual and social behaviours that contribute to the risk of HIV infection. The article considers the ‘edu’ part of this edutainment programme, specifically with the nature of the lessons and with the form of ‘disciplining’ the narratives presuppose for gendered and sexual subjects. Central to this critical and constructivist exploration of the gender relationships that are validated and expurgated are Foucault’s notions of discourse and confession as a technology of self. We argue that the series presents a range of different gendered and sexual subjectivities but implicitly endorses a modern subjectivity and transformation at the level of the individual.
- Full Text:
- Date Issued: 2017
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143381 , vital:38241 , DOI: 10.1080/00020184.2017.1285671
- Description: Confession is a central disciplining technology deployed in the second series of Intersexions, a popular South African TV series that seeks to change sexual and social behaviours that contribute to the risk of HIV infection. The article considers the ‘edu’ part of this edutainment programme, specifically with the nature of the lessons and with the form of ‘disciplining’ the narratives presuppose for gendered and sexual subjects. Central to this critical and constructivist exploration of the gender relationships that are validated and expurgated are Foucault’s notions of discourse and confession as a technology of self. We argue that the series presents a range of different gendered and sexual subjectivities but implicitly endorses a modern subjectivity and transformation at the level of the individual.
- Full Text:
- Date Issued: 2017
A constructivist deconstruction of post-apartheid South Africa’s trade negotiation strategies: the politics of development and global value chains
- Authors: Pillay, Morgenie
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64731 , vital:28596
- Description: Expected release date-May 2020
- Full Text:
- Date Issued: 2015
- Authors: Pillay, Morgenie
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64731 , vital:28596
- Description: Expected release date-May 2020
- Full Text:
- Date Issued: 2015
Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae)
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
Human, vector and parasite Hsp90 proteins: a comparative bioinformatics analysis
- Faya, Ngonidzashe, Penkler, David L, Tastan Bishop, Özlem
- Authors: Faya, Ngonidzashe , Penkler, David L , Tastan Bishop, Özlem
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148038 , vital:38704 , DOI: 10.1016/j.fob.2015.11.003
- Description: The treatment of protozoan parasitic diseases is challenging, and thus identification and analysis of new drug targets is important. Parasites survive within host organisms, and some need intermediate hosts to complete their life cycle. Changing host environment puts stress on parasites, and often adaptation is accompanied by the expression of large amounts of heat shock proteins (Hsps). Among Hsps, Hsp90 proteins play an important role in stress environments. Yet, there has been little computational research on Hsp90 proteins to analyze them comparatively as potential parasitic drug targets. Here, an attempt was made to gain detailed insights into the differences between host, vector and parasitic Hsp90 proteins by large-scale bioinformatics analysis.
- Full Text:
- Date Issued: 2015
- Authors: Faya, Ngonidzashe , Penkler, David L , Tastan Bishop, Özlem
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148038 , vital:38704 , DOI: 10.1016/j.fob.2015.11.003
- Description: The treatment of protozoan parasitic diseases is challenging, and thus identification and analysis of new drug targets is important. Parasites survive within host organisms, and some need intermediate hosts to complete their life cycle. Changing host environment puts stress on parasites, and often adaptation is accompanied by the expression of large amounts of heat shock proteins (Hsps). Among Hsps, Hsp90 proteins play an important role in stress environments. Yet, there has been little computational research on Hsp90 proteins to analyze them comparatively as potential parasitic drug targets. Here, an attempt was made to gain detailed insights into the differences between host, vector and parasitic Hsp90 proteins by large-scale bioinformatics analysis.
- Full Text:
- Date Issued: 2015
Shifting white identities in South Africa: white Africanness and the struggle for racial justice
- Authors: Matthews, Sally
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142180 , vital:38056 , DOI: 10.25159/2413-3086/3821
- Description: The end of apartheid predictably caused something of an identity crisis for white South Africans. The sense of uncertainty about what it means to be white has led to much public debate about whiteness in South Africa, as well as a growing body of literature on whites in post-apartheid South Africa. One of the many responses to this need to rethink white identity has been the claim by some that white South Africans can be considered to be African or ought to begin to think of themselves as being African. This paper argues that whites' assertion of an African identity does not necessarily assist in the achievement of racial justice, but that some kind of shift in white identity is required in order for whites to be able to contribute to the achievement of a racially just South Africa. In making this argument, the paper brings contemporary discussions on race and whiteness, and in particular discussions about racial eliminativism, to bear on the question of whether or not white South Africans may rightly claim an African identity.
- Full Text:
- Date Issued: 2015
- Authors: Matthews, Sally
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142180 , vital:38056 , DOI: 10.25159/2413-3086/3821
- Description: The end of apartheid predictably caused something of an identity crisis for white South Africans. The sense of uncertainty about what it means to be white has led to much public debate about whiteness in South Africa, as well as a growing body of literature on whites in post-apartheid South Africa. One of the many responses to this need to rethink white identity has been the claim by some that white South Africans can be considered to be African or ought to begin to think of themselves as being African. This paper argues that whites' assertion of an African identity does not necessarily assist in the achievement of racial justice, but that some kind of shift in white identity is required in order for whites to be able to contribute to the achievement of a racially just South Africa. In making this argument, the paper brings contemporary discussions on race and whiteness, and in particular discussions about racial eliminativism, to bear on the question of whether or not white South Africans may rightly claim an African identity.
- Full Text:
- Date Issued: 2015
An exploration of the principle of Dance Movement Therapy in water resource management research practice:
- Authors: Copteros, Athina
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/142016 , vital:38024 , ISBN PECS Conference: Social-ecological dynamics in the Anthropocene, Spier Estate, Cape Town, 2-5 November , http://www.pecs-science.org/research/news/news/2015pecsconferencesocialecologicaldynamicsintheanthropocene.5.40768cbb14b32a0480b694.html
- Description: An exploration of the principle of Dance Movement Therapy in water resource management research practice
- Full Text:
- Date Issued: 2015
- Authors: Copteros, Athina
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/142016 , vital:38024 , ISBN PECS Conference: Social-ecological dynamics in the Anthropocene, Spier Estate, Cape Town, 2-5 November , http://www.pecs-science.org/research/news/news/2015pecsconferencesocialecologicaldynamicsintheanthropocene.5.40768cbb14b32a0480b694.html
- Description: An exploration of the principle of Dance Movement Therapy in water resource management research practice
- Full Text:
- Date Issued: 2015
Sculpting with fire: celebrating ephemerality at AfrikaBurn 2015 in the Tankwa Karoo, South Africa
- Authors: Steele, John
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/957 , vital:30075
- Description: Land art, and some installation art, is usually aimed at relatively temporarily manipulating the surface of the earth. AfrikaBurn takes place annually in the near-desert of the Tankwa Karoo, South Africa. It is a communal event unique to Africa, and manifests as a fleeting week-long series of interventions in the natural environment, partially aimed at creating and then actively destroying free-standing public sculptures, some of which are huge and intricate. AfrikaBurn gives any one of the thousands of participants an opportunity to be inspired on any scale to generate artworks that take into account a principle that no debris whatsoever is left behind on the surface of the earth after a week-long celebration of creative energies. Unlike, for instance, an artwork built on the edge of the Indian Ocean in the Eastern Cape, where rough tidal seas would ensure gradual destruction, at AfrikaBurn, the sacrificial method of choice is controlled rapid burning, under the direction of a specified firemaster. This paper seeks to unbundle some aspects of land and installation art in Southern Africa with specific reference to AfrikaBurn 2015 events and anti-fracking initiatives. This is within a context that takes into account recognition that even seemingly durable public sculptures are subject to change and may even physically disappear with the passing of time.
- Full Text:
- Date Issued: 2015
- Authors: Steele, John
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/957 , vital:30075
- Description: Land art, and some installation art, is usually aimed at relatively temporarily manipulating the surface of the earth. AfrikaBurn takes place annually in the near-desert of the Tankwa Karoo, South Africa. It is a communal event unique to Africa, and manifests as a fleeting week-long series of interventions in the natural environment, partially aimed at creating and then actively destroying free-standing public sculptures, some of which are huge and intricate. AfrikaBurn gives any one of the thousands of participants an opportunity to be inspired on any scale to generate artworks that take into account a principle that no debris whatsoever is left behind on the surface of the earth after a week-long celebration of creative energies. Unlike, for instance, an artwork built on the edge of the Indian Ocean in the Eastern Cape, where rough tidal seas would ensure gradual destruction, at AfrikaBurn, the sacrificial method of choice is controlled rapid burning, under the direction of a specified firemaster. This paper seeks to unbundle some aspects of land and installation art in Southern Africa with specific reference to AfrikaBurn 2015 events and anti-fracking initiatives. This is within a context that takes into account recognition that even seemingly durable public sculptures are subject to change and may even physically disappear with the passing of time.
- Full Text:
- Date Issued: 2015
Shifting the priority from giving voice to listening: journalism new
- Garman, Anthea, Malila, Vanessa
- Authors: Garman, Anthea , Malila, Vanessa
- Date: 2015
- Language: English
- Type: text , article
- Identifier: vital:38355 , http://hdl.handle.net/10520/EJC175773
- Description: If, as the critics have argued, the South African media prioritise the voices of elite, middleclass South Africans, then the majority of South Africans are certainly invisible in the mainstream media. Kate Lacey argues that "listening is at the heart of what it means to be in the world, to be active, to be political" (2013: 163), and as such more than just providing a 'voice' for citizens, the media needs to be engaged in active listening to allow audiences to feel 'heard'. Servaes and Malikhao argue that people are 'voiceless' not because they have nothing to say, but because "nobody cares to listen to them" (2005: 91).
- Full Text:
- Date Issued: 2015
- Authors: Garman, Anthea , Malila, Vanessa
- Date: 2015
- Language: English
- Type: text , article
- Identifier: vital:38355 , http://hdl.handle.net/10520/EJC175773
- Description: If, as the critics have argued, the South African media prioritise the voices of elite, middleclass South Africans, then the majority of South Africans are certainly invisible in the mainstream media. Kate Lacey argues that "listening is at the heart of what it means to be in the world, to be active, to be political" (2013: 163), and as such more than just providing a 'voice' for citizens, the media needs to be engaged in active listening to allow audiences to feel 'heard'. Servaes and Malikhao argue that people are 'voiceless' not because they have nothing to say, but because "nobody cares to listen to them" (2005: 91).
- Full Text:
- Date Issued: 2015
The photophysical properties of multi-functional quantum dots-magnetic nanoparticles—indium octacarboxyphthalocyanine nanocomposite
- Tshangana, Charmaine, Nyokong, Tebello
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189876 , vital:44942 , xlink:href="https://doi.org/10.1007/s10895-014-1497-6"
- Description: This work presents the development of a multifunctional hybrid nanoparticle made of L-glutathione capped quantum dots (GSH-CdSe@ZnS), amino functionalized Fe3O4 magnetic nanoparticles and indium octacarboxy phthalocyanine (ClInPc(COOH)8). In this work we investigate the photophysical properties of the individual components and the hybrid nanoparticle, in addition we study the energy transfer (Förster Resonance Energy Transfer (FRET)) in the complex. FRET efficiencies of ~48 % were obtained for energy transfer between the QDs (when alone or linked to MNPs). Both triplet yields and lifetimes of ClInPc(COOH)8 increase in the nanocomposite, with a decrease in fluorescence lifetime. The hybrid nanoparticle showed improved photophysical properties and as a result can be used in photodynamic therapy.
- Full Text:
- Date Issued: 2015
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189876 , vital:44942 , xlink:href="https://doi.org/10.1007/s10895-014-1497-6"
- Description: This work presents the development of a multifunctional hybrid nanoparticle made of L-glutathione capped quantum dots (GSH-CdSe@ZnS), amino functionalized Fe3O4 magnetic nanoparticles and indium octacarboxy phthalocyanine (ClInPc(COOH)8). In this work we investigate the photophysical properties of the individual components and the hybrid nanoparticle, in addition we study the energy transfer (Förster Resonance Energy Transfer (FRET)) in the complex. FRET efficiencies of ~48 % were obtained for energy transfer between the QDs (when alone or linked to MNPs). Both triplet yields and lifetimes of ClInPc(COOH)8 increase in the nanocomposite, with a decrease in fluorescence lifetime. The hybrid nanoparticle showed improved photophysical properties and as a result can be used in photodynamic therapy.
- Full Text:
- Date Issued: 2015
Physicochemical and photodynamic antimicrobial chemotherapy studies of mono-and tetra-pyridyloxy substituted indium (III) phthalocyanines
- Osifeko, Olawale, Durmus, Mahmut, Nyokong, Tebello
- Authors: Osifeko, Olawale , Durmus, Mahmut , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189547 , vital:44856 , xlink:href="https://doi.org/10.1016/j.jphotochem.2014.12.011"
- Description: The synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction.
- Full Text:
- Date Issued: 2015
- Authors: Osifeko, Olawale , Durmus, Mahmut , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189547 , vital:44856 , xlink:href="https://doi.org/10.1016/j.jphotochem.2014.12.011"
- Description: The synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction.
- 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
Reinventing the oral word and returning it to the community via technauriture
- Kaschula, Russell H, Dlutu, Bongiwe
- Authors: Kaschula, Russell H , Dlutu, Bongiwe
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/67052 , vital:29024 , https://books.google.co.za/books?id=6IpwCgAAQBAJ
- Description: publisher version , From Introduction: The aim of this article is to situate the importance of orality in rural communities within the paradigm of Technauriture, which is defined below. The chapter will also explore/describe the process of orality supported through community meetings, oral histories, and story-telling, and how it interacts with the recording process facilitated through modern technology, as well as the return of the oral material via technology. These objectives will be pursued as part of empirical data collected at Tshani, an area falling within the in Mankosi tribal authority in the Eastern Cape Province of South Africa. Mankosi’s twelve villages are inhabited by amaXhosa people and is situated in the Ngqeleni district in the former Transkei region. Mankosi is about 76 kilometres away from Mthatha, the major city in that area. These villages are under the Nyandeni Local Municipality and are regarded as very disadvantaged. There is poor sanitation, gravel roads, and few local people have access to electricity. Most of the villagers depend on government support grants. These include Child Support Grants, Old Age Grants, Disability Grants, and Foster-Care Grants. Furthermore, most of the community is involved in small-scale agriculture for survival. People often move, temporarily, from their village to towns in order to gain employment, including domestic work and working on the mines in the mineral rich Gauteng Province. They send cash remittances home to their families. The primary technological devices that people in the village are familiar with would be radio and the cell phone. Even television sets are relatively uncommon.
- Full Text: false
- Date Issued: 2015
- Authors: Kaschula, Russell H , Dlutu, Bongiwe
- Date: 2015
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/67052 , vital:29024 , https://books.google.co.za/books?id=6IpwCgAAQBAJ
- Description: publisher version , From Introduction: The aim of this article is to situate the importance of orality in rural communities within the paradigm of Technauriture, which is defined below. The chapter will also explore/describe the process of orality supported through community meetings, oral histories, and story-telling, and how it interacts with the recording process facilitated through modern technology, as well as the return of the oral material via technology. These objectives will be pursued as part of empirical data collected at Tshani, an area falling within the in Mankosi tribal authority in the Eastern Cape Province of South Africa. Mankosi’s twelve villages are inhabited by amaXhosa people and is situated in the Ngqeleni district in the former Transkei region. Mankosi is about 76 kilometres away from Mthatha, the major city in that area. These villages are under the Nyandeni Local Municipality and are regarded as very disadvantaged. There is poor sanitation, gravel roads, and few local people have access to electricity. Most of the villagers depend on government support grants. These include Child Support Grants, Old Age Grants, Disability Grants, and Foster-Care Grants. Furthermore, most of the community is involved in small-scale agriculture for survival. People often move, temporarily, from their village to towns in order to gain employment, including domestic work and working on the mines in the mineral rich Gauteng Province. They send cash remittances home to their families. The primary technological devices that people in the village are familiar with would be radio and the cell phone. Even television sets are relatively uncommon.
- Full Text: false
- Date Issued: 2015
Wisdom as an aim of higher education
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275765 , vital:55077 , xlink:href="https://doi.org/10.1007/s10790-014-9443-z"
- Description: A central concern of theoretical speculation about education is the kind of epistemic states that education can and should aim to achieve. One such epistemic state, long neglected in both education theory and philosophy, is wisdom. Might wisdom be something that educators should aim for? And might it be something that their students can achieve? My answer will be a qualified yes.
- Full Text:
- Date Issued: 2015
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275765 , vital:55077 , xlink:href="https://doi.org/10.1007/s10790-014-9443-z"
- Description: A central concern of theoretical speculation about education is the kind of epistemic states that education can and should aim to achieve. One such epistemic state, long neglected in both education theory and philosophy, is wisdom. Might wisdom be something that educators should aim for? And might it be something that their students can achieve? My answer will be a qualified yes.
- Full Text:
- Date Issued: 2015
(Ferrocenylpyrazolyl) zinc (II) benzoates as catalysts for the ring opening polymerization of ε-caprolactone
- Obuah, Collins, Lochee, Yemanlall, Jordaan, Johan H L, Otto, Daniel P, Nyokong, Tebello, Darkwa, James
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189515 , vital:44853 , xlink:href="https://doi.org/10.1016/j.poly.2015.02.007"
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3 COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of e-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1 H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 107 h1 mol1 at 110 C.
- Full Text:
- Date Issued: 2015
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189515 , vital:44853 , xlink:href="https://doi.org/10.1016/j.poly.2015.02.007"
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3 COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of e-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1 H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 107 h1 mol1 at 110 C.
- Full Text:
- Date Issued: 2015
Isolation and structure elucidation of halogenated metabolites from Portieria hornemannii and Portieria tripinnata
- Authors: Adam, Mohammed
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64674 , vital:28591
- Description: The red marine algal genus, Portieria, is known to produce a number of potent cytotoxic compounds with anticancer potential. The most important anticancer lead produced by this genus is the compound halomon. Unfortunately, the lack of sufficient quantities of this compound hampered its further development. Two Portieria species, Portieria hornemannii and Portieria tripinnata, are found along the South African coastline. Recent studies, based on DNA analysis, suggest that Portieria hornemannii may in fact be divided into several cryptic species. The current project is part of a larger study designed to investigate the use of secondary metabolites to identify new marine algal species. In this study 1H NMR profiles of the organic extracts of selected Portieria spp were compared in order to identify new species. Selected compounds were then isolated and characterised as potential chemotaxonomic markers. Four halogenated monoterpenes were isolated from Portieria hornemannii. Two of these were new compounds 4-(3-bromo-4-chloro-4-methylpentyl)-3-chlorofuran-2(5H)-one, which were isomers of each other. The two known compounds had been previously isolated from Portieria hornemannii samples off the Madagascar coast. These compounds could prove to be useful as chemotaxonomic marker compounds, as they have never been isolated from any other species of marine algae. Three known halogenated monoterpenes were isolated from Portieria tripinnata. These compounds had been previously isolated from different species of marine algae and therefore, could not serve as chemotaxonomic marker compounds for this species of marine alga. Further work needs to be done on Portieria tripinnata, with regards to its chemistry, as it is a species of marine algae that has not been previously researched.
- Full Text:
- Date Issued: 2015
- Authors: Adam, Mohammed
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64674 , vital:28591
- Description: The red marine algal genus, Portieria, is known to produce a number of potent cytotoxic compounds with anticancer potential. The most important anticancer lead produced by this genus is the compound halomon. Unfortunately, the lack of sufficient quantities of this compound hampered its further development. Two Portieria species, Portieria hornemannii and Portieria tripinnata, are found along the South African coastline. Recent studies, based on DNA analysis, suggest that Portieria hornemannii may in fact be divided into several cryptic species. The current project is part of a larger study designed to investigate the use of secondary metabolites to identify new marine algal species. In this study 1H NMR profiles of the organic extracts of selected Portieria spp were compared in order to identify new species. Selected compounds were then isolated and characterised as potential chemotaxonomic markers. Four halogenated monoterpenes were isolated from Portieria hornemannii. Two of these were new compounds 4-(3-bromo-4-chloro-4-methylpentyl)-3-chlorofuran-2(5H)-one, which were isomers of each other. The two known compounds had been previously isolated from Portieria hornemannii samples off the Madagascar coast. These compounds could prove to be useful as chemotaxonomic marker compounds, as they have never been isolated from any other species of marine algae. Three known halogenated monoterpenes were isolated from Portieria tripinnata. These compounds had been previously isolated from different species of marine algae and therefore, could not serve as chemotaxonomic marker compounds for this species of marine alga. Further work needs to be done on Portieria tripinnata, with regards to its chemistry, as it is a species of marine algae that has not been previously researched.
- Full Text:
- Date Issued: 2015