The design, synthesis and antiplasmodial activity of a series of halogenated fosmidomycin analogues and hybrid drugs
- Authors: Afolayan, Anthonia Folake
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64370 , vital:28538
- Description: Malaria continues to be a devastating disease and a major cause of death in sub-Saharan Africa. With resistance against most of the available antimalarial drugs, there is a need for ongoing research and development of antimalarial agents. Fosmidomycin and its acetyl analogue FR900098 have been identified as potent inhibitors of Plasmodium falciparum, the causative agent of the most deadly form of malaria. Clinical trials of these agents have revealed poor absorption due to their high hydrophilicity. In the present studies the effect of halogenation of the acyl chain as well as the biological effect of extending the acyl sidechain was explored. This provided the basis on which fosmidomycin hybrids were designed to investigate the feasibility of hybrid extending into NADPH binding pocket. Synthesis of a series of halogenated FR900098 analogues was carried out in three stages. This included i) The introduction of the phosphonate group by reaction with 1,3dibromopropane in an Arbuzov reaction, ii) The introduction of a hydroxamate group by reaction of the propyl phosphonate by means of a nucleophilic substitution reaction with BocNHOBn and iii) The introduction of a halogenated acyl side chain on a protected fosmidomycin backbone. The synthesis of fosmidomycin-hybrids for which chloroquinefosmidomycin hybrids were used as the prototype, involved convergence of the two separately constructed moieties i.e. fosmidomycin and the quinoline moieties in a covalent linkage. The quinoline moiety was easily synthesized from the reaction of 4,7dichloroquinoline with 1,2-diamino ethane. The aminoquinoline so formed resulted in chloroquine-fosmidomycin hybrids 3.8 and 3.9 when reacted with halogenated FR900098 analogues. Antiplasmodial assays were conducted on the chloroquine-fosmidomycin hybrids and the halogenated fosmidomycin derivatives against the chloroquine resistant Gambian FCR-3 strain of P. falciparum. The most potent iodoacetyl fosmidomycin analogues 2.21 gave an IC50 value of 5.54 µM which is eight times more potent than the known antiplasmodial FR900098 which gave an IC50 value of 41.67 µM. All the halogenated FR900098 analogues showed better antiplasmodial activity than their non-halogenated derivatives. This indicated that the presence of halogens in the FR900098 analogues contributes to their biological Chapter 1 Literature review activity. The acetyl and propyl linked hybrids 3.8 and 3.9 showed potent antiplasmodial activity with IC50 values of 0.18 and 0.82 µM respectively. These were by far the most potent hybrids synthesized and provided leads for a new class of promising antimalarial agents. Preliminary E. coli DXR enzyme inhibition assays were carried out on the halogenated fosmidomycin analogues. The results showed good inhibition of the enzyme by the phosphonic acids of the chloroacetyl and chloropropyl analogues 2.1 and 2.2 respectively. Molecular modelling of the compounds on E. coli (PDB code: 2EGH) and P. falciparum (PDB code: 3AUA) DXR showed strong binding of the halogenated fosmidomycin analogues while the hybrids in the absence of docked NADPH showed minimum binding to the enzymes.
- Full Text:
- Date Issued: 2012
- Authors: Afolayan, Anthonia Folake
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64370 , vital:28538
- Description: Malaria continues to be a devastating disease and a major cause of death in sub-Saharan Africa. With resistance against most of the available antimalarial drugs, there is a need for ongoing research and development of antimalarial agents. Fosmidomycin and its acetyl analogue FR900098 have been identified as potent inhibitors of Plasmodium falciparum, the causative agent of the most deadly form of malaria. Clinical trials of these agents have revealed poor absorption due to their high hydrophilicity. In the present studies the effect of halogenation of the acyl chain as well as the biological effect of extending the acyl sidechain was explored. This provided the basis on which fosmidomycin hybrids were designed to investigate the feasibility of hybrid extending into NADPH binding pocket. Synthesis of a series of halogenated FR900098 analogues was carried out in three stages. This included i) The introduction of the phosphonate group by reaction with 1,3dibromopropane in an Arbuzov reaction, ii) The introduction of a hydroxamate group by reaction of the propyl phosphonate by means of a nucleophilic substitution reaction with BocNHOBn and iii) The introduction of a halogenated acyl side chain on a protected fosmidomycin backbone. The synthesis of fosmidomycin-hybrids for which chloroquinefosmidomycin hybrids were used as the prototype, involved convergence of the two separately constructed moieties i.e. fosmidomycin and the quinoline moieties in a covalent linkage. The quinoline moiety was easily synthesized from the reaction of 4,7dichloroquinoline with 1,2-diamino ethane. The aminoquinoline so formed resulted in chloroquine-fosmidomycin hybrids 3.8 and 3.9 when reacted with halogenated FR900098 analogues. Antiplasmodial assays were conducted on the chloroquine-fosmidomycin hybrids and the halogenated fosmidomycin derivatives against the chloroquine resistant Gambian FCR-3 strain of P. falciparum. The most potent iodoacetyl fosmidomycin analogues 2.21 gave an IC50 value of 5.54 µM which is eight times more potent than the known antiplasmodial FR900098 which gave an IC50 value of 41.67 µM. All the halogenated FR900098 analogues showed better antiplasmodial activity than their non-halogenated derivatives. This indicated that the presence of halogens in the FR900098 analogues contributes to their biological Chapter 1 Literature review activity. The acetyl and propyl linked hybrids 3.8 and 3.9 showed potent antiplasmodial activity with IC50 values of 0.18 and 0.82 µM respectively. These were by far the most potent hybrids synthesized and provided leads for a new class of promising antimalarial agents. Preliminary E. coli DXR enzyme inhibition assays were carried out on the halogenated fosmidomycin analogues. The results showed good inhibition of the enzyme by the phosphonic acids of the chloroacetyl and chloropropyl analogues 2.1 and 2.2 respectively. Molecular modelling of the compounds on E. coli (PDB code: 2EGH) and P. falciparum (PDB code: 3AUA) DXR showed strong binding of the halogenated fosmidomycin analogues while the hybrids in the absence of docked NADPH showed minimum binding to the enzymes.
- Full Text:
- Date Issued: 2012
The direct use value of municipal commonage goods and services to urban households in the Eastern Cape, South Africa
- Davenport, Nicholas A, Shackleton, Charlie M, Gambiza, James
- Authors: Davenport, Nicholas A , Shackleton, Charlie M , Gambiza, James
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181071 , vital:43696 , xlink:href="https://doi.org/10.1016/j.landusepol.2011.09.008"
- Description: To redress past racial discrepancies in ownership and tenure, the ANC government of South Africa initiated programmes to make land accessible to the previously disadvantaged. A key component of the national land reform programme was the provision of commonage lands to urban municipalities for use by the urban poor. However, there has been no assessment of the contribution that urban commonage makes to previously disadvantaged households. This study assessed the economic benefits of the commonage programme to local households, through an in-depth survey of 90 households across three small towns in the Eastern Cape of South Africa. We examined the marketed and non-marketed consumptive direct-use values of land-based livelihoods on commonage, calculated via the ‘own reported values’ approach. The results indicate that a proportion of South Africa's urban population rely to some degree on municipal commonage for part of their livelihoods. Commonage contributions to total livelihood incomes ranged between 14 and 20%. If the contributions from commonage were excluded, the incomes of over 10% of households in each study town would drop below the poverty line. Overall, the value of harvests from commonage was worth over R1 000 (US$ 142) per hectare per year and over R4.7 million (US$ 0.68 million) per commonage per year. However, the extent and nature of use and reliance was not uniform among households, so that we developed a typology of commonage users, with four types being identified. However, rapidly growing urban populations and high levels of poverty potentially threaten the sustainability of commonage resource use. Yet the national land reform programme focuses largely on the transfer of land to municipalities and not on sustainable management. Municipalities, in turn, invest relatively little in commonage management, and the little they do is focussed on livestock production. Non-timber forest products are not considered at all, even though this study shows that they are a vital resource for the urban poor, notably for energy and construction materials.
- Full Text:
- Date Issued: 2012
- Authors: Davenport, Nicholas A , Shackleton, Charlie M , Gambiza, James
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181071 , vital:43696 , xlink:href="https://doi.org/10.1016/j.landusepol.2011.09.008"
- Description: To redress past racial discrepancies in ownership and tenure, the ANC government of South Africa initiated programmes to make land accessible to the previously disadvantaged. A key component of the national land reform programme was the provision of commonage lands to urban municipalities for use by the urban poor. However, there has been no assessment of the contribution that urban commonage makes to previously disadvantaged households. This study assessed the economic benefits of the commonage programme to local households, through an in-depth survey of 90 households across three small towns in the Eastern Cape of South Africa. We examined the marketed and non-marketed consumptive direct-use values of land-based livelihoods on commonage, calculated via the ‘own reported values’ approach. The results indicate that a proportion of South Africa's urban population rely to some degree on municipal commonage for part of their livelihoods. Commonage contributions to total livelihood incomes ranged between 14 and 20%. If the contributions from commonage were excluded, the incomes of over 10% of households in each study town would drop below the poverty line. Overall, the value of harvests from commonage was worth over R1 000 (US$ 142) per hectare per year and over R4.7 million (US$ 0.68 million) per commonage per year. However, the extent and nature of use and reliance was not uniform among households, so that we developed a typology of commonage users, with four types being identified. However, rapidly growing urban populations and high levels of poverty potentially threaten the sustainability of commonage resource use. Yet the national land reform programme focuses largely on the transfer of land to municipalities and not on sustainable management. Municipalities, in turn, invest relatively little in commonage management, and the little they do is focussed on livestock production. Non-timber forest products are not considered at all, even though this study shows that they are a vital resource for the urban poor, notably for energy and construction materials.
- Full Text:
- Date Issued: 2012
The economics of greening the Grahamstown National Arts Festival in South Africa
- Dobson, Blaise, Snowball, Jeanette D
- Authors: Dobson, Blaise , Snowball, Jeanette D
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71445 , vital:29851 , https://hdl.handle.net/10520/EJC132010
- Description: The article analyses the broad history underpinning the notion of sustainable development and its context within the events industry in South Africa. It explores the willingness of festival-goers to pay for a hypothetical recycling programme to reduce the negative externalities of the Festival. Results show that festival-goers were, on average, willing to pay an additional R2.30 per "green" ticket to fund the proposed programme. A statistical regression was used to explore the determinants of willing-to-pay. If applied to all tickets, the total willing-to-pay amount far exceeded the actual cost of the recycling programme.
- Full Text: false
- Date Issued: 2012
- Authors: Dobson, Blaise , Snowball, Jeanette D
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71445 , vital:29851 , https://hdl.handle.net/10520/EJC132010
- Description: The article analyses the broad history underpinning the notion of sustainable development and its context within the events industry in South Africa. It explores the willingness of festival-goers to pay for a hypothetical recycling programme to reduce the negative externalities of the Festival. Results show that festival-goers were, on average, willing to pay an additional R2.30 per "green" ticket to fund the proposed programme. A statistical regression was used to explore the determinants of willing-to-pay. If applied to all tickets, the total willing-to-pay amount far exceeded the actual cost of the recycling programme.
- Full Text: false
- Date Issued: 2012
The economics of suicide in South Africa
- Authors: Botha, Ferdi
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396168 , vital:69155 , xlink:href="https://doi.org/10.1111/j.1813-6982.2012.01336.x"
- Description: This study investigates the economics of suicide in South Africa using the Mortality and Causes of Death data from death notification as well as regional economic data for the 2006-2008 period. Using an inflation rate that varies by month and across province of residence as a proxy for economic performance, the results indicate a negative relationship between inflation and suicide, suggesting that suicides are countercyclical. When controlling for month and province fixed effects, however, the inflation coefficient, albeit remaining negative, is no longer significant, except in the female sample. Suicide is more prevalent among younger individuals, while the greatest proportion of suicide is seen among men. Suicides also exhibit a strong seasonal variation, with peaks in spring and summer, with December having the highest suicide prevalence. The overall results indicate a negative but insignificant relationship between economic performance and suicide in South Africa, with socio-economic differences and individual characteristics accounting for most of the variation in suicide.
- Full Text:
- Date Issued: 2012
- Authors: Botha, Ferdi
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396168 , vital:69155 , xlink:href="https://doi.org/10.1111/j.1813-6982.2012.01336.x"
- Description: This study investigates the economics of suicide in South Africa using the Mortality and Causes of Death data from death notification as well as regional economic data for the 2006-2008 period. Using an inflation rate that varies by month and across province of residence as a proxy for economic performance, the results indicate a negative relationship between inflation and suicide, suggesting that suicides are countercyclical. When controlling for month and province fixed effects, however, the inflation coefficient, albeit remaining negative, is no longer significant, except in the female sample. Suicide is more prevalent among younger individuals, while the greatest proportion of suicide is seen among men. Suicides also exhibit a strong seasonal variation, with peaks in spring and summer, with December having the highest suicide prevalence. The overall results indicate a negative but insignificant relationship between economic performance and suicide in South Africa, with socio-economic differences and individual characteristics accounting for most of the variation in suicide.
- Full Text:
- Date Issued: 2012
The effect of harvesting approaches on fruit yield, embelin concentration and regrowth dynamics of the forest shrub, Embelia tsjeriam-cottam, in central India
- Pandey, Ashok K, Shackleton, Charlie M
- Authors: Pandey, Ashok K , Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181094 , vital:43698 , xlink:href="https://doi.org/10.1016/j.foreco.2011.11.015"
- Description: Embelia tsjeriam-cottam Roem and Schult A. DC. (Myrsinaceae), popularly known as Vaividang, is a vulnerable forest species because of the high demand of fruits for medicinal purposes. It is in great demand in ayurveda and the pharmaceutical industry (>100 t/yr), which has imposed tremendous pressure on some natural populations. The fruits contain embelin (a benzoquinone derivative), which has wide clinical applications. Considering the importance, growing use and decreasing populations in some areas of its natural habitat, a study on development of sustainable harvesting practices of E. tsjeriam-cottam fruits was conducted in Chhattisgarh, in central India. Experiments were laid out in Dhamtari, Marvahi and Bilaspur forest divisions of the state covering both protected and open forests in a randomized design with three replications. At each site, quadrats of 40 × 20 m were laid out to study the effect of two fruit harvesting methods and four harvesting intensities on fruit yield, and regeneration of the species. Fruits were analyzed for their embelin content by HPLC method. This study is the first to experimentally assess the consequences of harvesting of E. tsjeriam-cottam fruits from India. It was found that up to 70% fruits could be hand plucked at the right time of maturity (December) to obtain quality produce without impacting the current population size. Since every year is not a good fruiting year, it is difficult to develop universal harvest regime for sustainable management of E. tsjeriam-cottam. The embelin content increased as fruits ripened, ranging from 1.01% to 5.63%. The adoption of sustainable harvesting practices will be helpful in sustainable management of E. tsjeriam-cottam and also provide income and livelihood opportunities to rural people on a sustainable basis.
- Full Text:
- Date Issued: 2012
- Authors: Pandey, Ashok K , Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181094 , vital:43698 , xlink:href="https://doi.org/10.1016/j.foreco.2011.11.015"
- Description: Embelia tsjeriam-cottam Roem and Schult A. DC. (Myrsinaceae), popularly known as Vaividang, is a vulnerable forest species because of the high demand of fruits for medicinal purposes. It is in great demand in ayurveda and the pharmaceutical industry (>100 t/yr), which has imposed tremendous pressure on some natural populations. The fruits contain embelin (a benzoquinone derivative), which has wide clinical applications. Considering the importance, growing use and decreasing populations in some areas of its natural habitat, a study on development of sustainable harvesting practices of E. tsjeriam-cottam fruits was conducted in Chhattisgarh, in central India. Experiments were laid out in Dhamtari, Marvahi and Bilaspur forest divisions of the state covering both protected and open forests in a randomized design with three replications. At each site, quadrats of 40 × 20 m were laid out to study the effect of two fruit harvesting methods and four harvesting intensities on fruit yield, and regeneration of the species. Fruits were analyzed for their embelin content by HPLC method. This study is the first to experimentally assess the consequences of harvesting of E. tsjeriam-cottam fruits from India. It was found that up to 70% fruits could be hand plucked at the right time of maturity (December) to obtain quality produce without impacting the current population size. Since every year is not a good fruiting year, it is difficult to develop universal harvest regime for sustainable management of E. tsjeriam-cottam. The embelin content increased as fruits ripened, ranging from 1.01% to 5.63%. The adoption of sustainable harvesting practices will be helpful in sustainable management of E. tsjeriam-cottam and also provide income and livelihood opportunities to rural people on a sustainable basis.
- Full Text:
- Date Issued: 2012
The end of the road for the Roman rule of risk in sale?
- Authors: Glover, Graham B
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70550 , vital:29674 , https://hdl.handle.net/10520/EJC127052
- Description: The venerable Roman rule of risk in the law of sale – “perfecta emptione periculum est emptoris” – has always been a rule that has courted controversy, be it in the South African legal system or others where it has operated. In an excellent piece of analytical historical scholarship titled “Perfecta emptione periculum est emptoris: Why all the fuss?” Van den Bergh argued in 2008 that, despite all the ink that has been spent on critiquing the rule in the thousands of years that have passed since its genesis, the rule has endured, and there are indeed reasons (partly practical and partly policy-related) that have justified its resilience. In this article I do not wish to dispute her carefully researched historiographical conclusions. Rather, I wish to suggest that circumstances may now have changed. The agent of this change is, not unexpectedly, the Consumer Protection Act 68 of 2008 (the act). The act, simply stated, changes the rule of risk that applies to consumer sale contracts. The way in which the legislation does so will be discussed fully in part 4 of the article below. But what does this legislative shift mean for the common-law rule, bearing in mind that not all contracts are contracts that fall under the act? In the remainder of the article I shall discuss whether the time has come for the common-law rule to take its bow, particularly in the light of the criticism it has always faced, the clear and consistent statements of policy that emerge from the act and comparative modern sources about where risk should fall, and the interests of fairness and uniformity of treatment of the parties to a sale contract.
- Full Text: false
- Date Issued: 2012
- Authors: Glover, Graham B
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70550 , vital:29674 , https://hdl.handle.net/10520/EJC127052
- Description: The venerable Roman rule of risk in the law of sale – “perfecta emptione periculum est emptoris” – has always been a rule that has courted controversy, be it in the South African legal system or others where it has operated. In an excellent piece of analytical historical scholarship titled “Perfecta emptione periculum est emptoris: Why all the fuss?” Van den Bergh argued in 2008 that, despite all the ink that has been spent on critiquing the rule in the thousands of years that have passed since its genesis, the rule has endured, and there are indeed reasons (partly practical and partly policy-related) that have justified its resilience. In this article I do not wish to dispute her carefully researched historiographical conclusions. Rather, I wish to suggest that circumstances may now have changed. The agent of this change is, not unexpectedly, the Consumer Protection Act 68 of 2008 (the act). The act, simply stated, changes the rule of risk that applies to consumer sale contracts. The way in which the legislation does so will be discussed fully in part 4 of the article below. But what does this legislative shift mean for the common-law rule, bearing in mind that not all contracts are contracts that fall under the act? In the remainder of the article I shall discuss whether the time has come for the common-law rule to take its bow, particularly in the light of the criticism it has always faced, the clear and consistent statements of policy that emerge from the act and comparative modern sources about where risk should fall, and the interests of fairness and uniformity of treatment of the parties to a sale contract.
- Full Text: false
- Date Issued: 2012
The implacable grandeur of the stranger
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229430 , vital:49673 , xlink:href="https://doi.org/10.1080/10137548.2013.799798"
- Description: South Africa is a nation of strangers, an uneasy mishmash of heterogeneous economic groupings, cultures and languages, a nation of marginalised minorities awkwardly pasted together. Numerous attempts have been made by its government to define and bolster a sense of nationalism and to create a sense of cohesion; however, a shadow side of this appeal for national identity has been the rise in xenophobic violence precipitated by the steady influx of refugees into the country. The title of this article is drawn from Albert Camus’s introduction to his disarming novella of dislocation, L’Etranger (1942), and I would like to explore some of the philosophical implications of representing strangers in different ways. Drawing on works by Zygmunt Bauman, Georg Simmel and Julia Kristeva, I will consider ambivalences towards the stranger represented in Magnet Theatre’s production (2010) of Die Vreemdeling [The Stranger], and pose a few questions about our relationship with the unknown. Attempts to familiarise the constituents of various communities with aspects of each other’s strangeness is a project which has typified much South African theatre in the past; and yet this is an approach which stands in sharp contrast to the importance granted processes of defamiliarisation first proposed so succinctly by Victor Shklovsky in 1917. Instead of attempts to harness and explain the unfamiliarity of others in order to communicate diversity, a celebration of the grandeur of the stranger may provide a more enriching alternative.
- Full Text:
- Date Issued: 2012
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229430 , vital:49673 , xlink:href="https://doi.org/10.1080/10137548.2013.799798"
- Description: South Africa is a nation of strangers, an uneasy mishmash of heterogeneous economic groupings, cultures and languages, a nation of marginalised minorities awkwardly pasted together. Numerous attempts have been made by its government to define and bolster a sense of nationalism and to create a sense of cohesion; however, a shadow side of this appeal for national identity has been the rise in xenophobic violence precipitated by the steady influx of refugees into the country. The title of this article is drawn from Albert Camus’s introduction to his disarming novella of dislocation, L’Etranger (1942), and I would like to explore some of the philosophical implications of representing strangers in different ways. Drawing on works by Zygmunt Bauman, Georg Simmel and Julia Kristeva, I will consider ambivalences towards the stranger represented in Magnet Theatre’s production (2010) of Die Vreemdeling [The Stranger], and pose a few questions about our relationship with the unknown. Attempts to familiarise the constituents of various communities with aspects of each other’s strangeness is a project which has typified much South African theatre in the past; and yet this is an approach which stands in sharp contrast to the importance granted processes of defamiliarisation first proposed so succinctly by Victor Shklovsky in 1917. Instead of attempts to harness and explain the unfamiliarity of others in order to communicate diversity, a celebration of the grandeur of the stranger may provide a more enriching alternative.
- Full Text:
- Date Issued: 2012
The narrative of vulnerability and deprivation in protection regimes for the internally displaced persons (IDPs) in Africa: an appraisal of the Kampala Convention
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128448 , vital:36110 , https://heinonline.org/HOL/Page?handle=hein.journals/laacydev16amp;div=14amp;g_sent=1amp;casa_token=amp;collection=journals
- Description: Prior to the 1990s, the phenomenon of internal displacement did not attract much attention from the international community. Most states, suspicious of the external interests in what they considered to be a purely internal matter were not keen to expose difficulties or suffering of their displaced citizens. And insistence on protection of the internally displaced by international organisations was seen as an affront to sovereignty.
- Full Text: false
- Date Issued: 2012
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128448 , vital:36110 , https://heinonline.org/HOL/Page?handle=hein.journals/laacydev16amp;div=14amp;g_sent=1amp;casa_token=amp;collection=journals
- Description: Prior to the 1990s, the phenomenon of internal displacement did not attract much attention from the international community. Most states, suspicious of the external interests in what they considered to be a purely internal matter were not keen to expose difficulties or suffering of their displaced citizens. And insistence on protection of the internally displaced by international organisations was seen as an affront to sovereignty.
- Full Text: false
- Date Issued: 2012
The nature and quality of the mathematical connections teachers make:
- Mhlolo, Michael K, Schäfer, Marc, Venkat, Hamsa
- Authors: Mhlolo, Michael K , Schäfer, Marc , Venkat, Hamsa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140893 , vital:37927 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC120887
- Description: Current reforms in mathematics education emphasise the need for pedagogy because it offers learners opportunities to develop their proficiency with complex high-level cognitive processes. One has always associated the ability to make mathematical connections, together with the teacher's role in teaching them, with deep mathematical understanding. This article examines the nature and quality of the mathematical connections that the teachers' representations of those connections enabled or constrained. The researchers made video recordings of four Grade 11 teachers as they taught a series of five lessons on algebra-related topics. The results showed that the teachers' representations of mathematical connections were either faulty or superficial in most cases. It compromised the learners' opportunities for making meaningful mathematical connections. The researchers concluded by suggesting that helping teachers to build their representation repertoires could increase the effectiveness of their instructional practices.
- Full Text:
- Date Issued: 2012
- Authors: Mhlolo, Michael K , Schäfer, Marc , Venkat, Hamsa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140893 , vital:37927 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC120887
- Description: Current reforms in mathematics education emphasise the need for pedagogy because it offers learners opportunities to develop their proficiency with complex high-level cognitive processes. One has always associated the ability to make mathematical connections, together with the teacher's role in teaching them, with deep mathematical understanding. This article examines the nature and quality of the mathematical connections that the teachers' representations of those connections enabled or constrained. The researchers made video recordings of four Grade 11 teachers as they taught a series of five lessons on algebra-related topics. The results showed that the teachers' representations of mathematical connections were either faulty or superficial in most cases. It compromised the learners' opportunities for making meaningful mathematical connections. The researchers concluded by suggesting that helping teachers to build their representation repertoires could increase the effectiveness of their instructional practices.
- Full Text:
- Date Issued: 2012
The photophysical and energy transfer behaviour of low symmetry phthalocyanine complexes conjugated to coreshell quantum dots
- Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243051 , vital:51111 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.07.016"
- Description: This work reports on the synthesis of new coreshell quantum dots (QDs)-low symmetry phthalocyanines conjugates. The energy transfer from QDs (donor) to phthalocyanines (acceptor) was investigated when the two are mixed together or chemically linked to each other. Ti monocarboxy phthalocyanine QDs-linked and Sn monocarboxy phthalocyanine QDs-linked gave the smallest centre-to-centre separation distance (r) corresponding to their higher Förster resonance energy transfer efficiencies which are estimated at 0.76 and 0.85 respectively. Higher energy transfer behaviour was achieved for all the covalently linked conjugates compared to their corresponding mixed counterparts. An improvement in triplet quantum yields and lifetimes was achieved for all the complexes in the presence of quantum dots, with the linked counterparts displaying excellent triplet state behaviour.
- Full Text:
- Date Issued: 2012
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243051 , vital:51111 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.07.016"
- Description: This work reports on the synthesis of new coreshell quantum dots (QDs)-low symmetry phthalocyanines conjugates. The energy transfer from QDs (donor) to phthalocyanines (acceptor) was investigated when the two are mixed together or chemically linked to each other. Ti monocarboxy phthalocyanine QDs-linked and Sn monocarboxy phthalocyanine QDs-linked gave the smallest centre-to-centre separation distance (r) corresponding to their higher Förster resonance energy transfer efficiencies which are estimated at 0.76 and 0.85 respectively. Higher energy transfer behaviour was achieved for all the covalently linked conjugates compared to their corresponding mixed counterparts. An improvement in triplet quantum yields and lifetimes was achieved for all the complexes in the presence of quantum dots, with the linked counterparts displaying excellent triplet state behaviour.
- Full Text:
- Date Issued: 2012
The pump room
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225764 , vital:49256 , xlink:href="https://doi.org/10.1080/10137548.2012.754084"
- Description: I like Allan Kolski Horwitz. He’s done great things for independent publishing in South Africa. Through his company, Botsotso, he’s probably responsible for publishing more poetry, prose and drama than any single person in the country today. The industriousness of his one-man operation has generously sponsored and nurtured thousands of pages of local literature over the course of many years. This is why it makes me so uncomfortable to say that I really don’t like this play. It gives me no pleasure to write a negative review, and especially not about books written by people I like. If I hadn’t already committed myself to writing this review, I would have avoided it. Nevertheless, I had, so I won’t.
- Full Text:
- Date Issued: 2012
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225764 , vital:49256 , xlink:href="https://doi.org/10.1080/10137548.2012.754084"
- Description: I like Allan Kolski Horwitz. He’s done great things for independent publishing in South Africa. Through his company, Botsotso, he’s probably responsible for publishing more poetry, prose and drama than any single person in the country today. The industriousness of his one-man operation has generously sponsored and nurtured thousands of pages of local literature over the course of many years. This is why it makes me so uncomfortable to say that I really don’t like this play. It gives me no pleasure to write a negative review, and especially not about books written by people I like. If I hadn’t already committed myself to writing this review, I would have avoided it. Nevertheless, I had, so I won’t.
- Full Text:
- Date Issued: 2012
The recognition of unenumerated rights in South Africa
- Krüger, Rósaan, Govindjee, Avinash
- Authors: Krüger, Rósaan , Govindjee, Avinash
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71093 , vital:29783 , https://hdl.handle.net/10520/EJC153177
- Description: In 1997 a South African man married a woman who, at the time of the conclusion of their marriage, was a national of a foreign country. The couple decided to set up home and start a family in South Africa. They were advised that the granting of a permanent residence permit to the wife would only be considered upon payment of a hefty application fee, and that she had to apply for the permit from outside South Africa. The couple was of the view that the high cost of the application coupled with their temporary separation at the time of the lodging of the application amounted to an unjustifiable limitation of their right to family life. One of the obstacles faced by the couple was the silence of the South Africa Constitution on the right to family life.
- Full Text: false
- Date Issued: 2012
- Authors: Krüger, Rósaan , Govindjee, Avinash
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71093 , vital:29783 , https://hdl.handle.net/10520/EJC153177
- Description: In 1997 a South African man married a woman who, at the time of the conclusion of their marriage, was a national of a foreign country. The couple decided to set up home and start a family in South Africa. They were advised that the granting of a permanent residence permit to the wife would only be considered upon payment of a hefty application fee, and that she had to apply for the permit from outside South Africa. The couple was of the view that the high cost of the application coupled with their temporary separation at the time of the lodging of the application amounted to an unjustifiable limitation of their right to family life. One of the obstacles faced by the couple was the silence of the South Africa Constitution on the right to family life.
- Full Text: false
- Date Issued: 2012
The role of culture in enabling or constraining the use of technology in higher education teaching and learning: the Commerce Curriculum Project
- Mostert, Markus, Snowball, Jeanette D, Boughey, Chrissie
- Authors: Mostert, Markus , Snowball, Jeanette D , Boughey, Chrissie
- Date: 2012
- Language: English
- Type: conference paper , text
- Identifier: http://hdl.handle.net/10962/61073 , vital:27945
- Description: This paper draws on a project located in one faculty at a South African university which aimed to use Information and Communication Technologies (ICTs) to enhance teaching and learning. More specifically, the paper uses Archer’s (1995, 1996, 2000, 1998) ‘analytical dualism’ and ‘morphogenesis’ to explore the way individuals involved in the project were able to exercise agency in departments which were relatively hostile to the goals they were aiming to pursue despite the wider cultural domain encompassing many ideas which construct the use of ICTs as significant in promoting student learning. The paper thus contributes to the culture/agency subtheme of the HECU6 conference. The paper begins by providing some background to the project before moving on to an exploration of the way Archer’s theoretical work was used to analyse data collected by project leaders.
- Full Text:
- Date Issued: 2012
- Authors: Mostert, Markus , Snowball, Jeanette D , Boughey, Chrissie
- Date: 2012
- Language: English
- Type: conference paper , text
- Identifier: http://hdl.handle.net/10962/61073 , vital:27945
- Description: This paper draws on a project located in one faculty at a South African university which aimed to use Information and Communication Technologies (ICTs) to enhance teaching and learning. More specifically, the paper uses Archer’s (1995, 1996, 2000, 1998) ‘analytical dualism’ and ‘morphogenesis’ to explore the way individuals involved in the project were able to exercise agency in departments which were relatively hostile to the goals they were aiming to pursue despite the wider cultural domain encompassing many ideas which construct the use of ICTs as significant in promoting student learning. The paper thus contributes to the culture/agency subtheme of the HECU6 conference. The paper begins by providing some background to the project before moving on to an exploration of the way Archer’s theoretical work was used to analyse data collected by project leaders.
- Full Text:
- Date Issued: 2012
The saga of South African POWs in Angola, 1975-82
- Authors: Baines, Gary F
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69882 , vital:29592 , http://dx.doi.org/10.5787/40-2-999
- Description: This article narrates the story of nine soldiers captured during and shortly after Operation Savannah, the codename for the South African Defence Force invasion of Angola in 1975–6. Eight of these soldiers were captured in Angola in three separate incidents by Angolan and/or Cuban forces, whereas the last was abducted from northern Namibia by SWAPO (the South West Africa Peoples’ Organisation). The article then provides a chronological account of the sequels to this story that interweaves a number of threads: first, the account relates the South African government’s attempts to suppress press coverage of these stories for fear of the political ‘fall-out’ that the matter might cause amongst the white electorate and in case it jeopardised secret negotiations to secure the release of the prisoners; and second, it uncovers the role played by intermediaries, especially the International Committee of the Red Cross (ICRC), in the sensitive and fraught negotiation process. It will be shown that the South African authorities adopted divergent approaches when dealing with SWAPO and the Angolans/Cubans to secure the release of prisoners of war (POWs). This is because the South African authorities regarded the former as involved in an internal insurrection whereas the latter were members of the military forces of sovereign states. Accordingly, they paid lip service to the Geneva Conventions in the case of Angolan and Cuban POWs but treated captured SWAPO cadres as ‘terrorists’ or ‘criminals’.
- Full Text:
- Date Issued: 2012
- Authors: Baines, Gary F
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69882 , vital:29592 , http://dx.doi.org/10.5787/40-2-999
- Description: This article narrates the story of nine soldiers captured during and shortly after Operation Savannah, the codename for the South African Defence Force invasion of Angola in 1975–6. Eight of these soldiers were captured in Angola in three separate incidents by Angolan and/or Cuban forces, whereas the last was abducted from northern Namibia by SWAPO (the South West Africa Peoples’ Organisation). The article then provides a chronological account of the sequels to this story that interweaves a number of threads: first, the account relates the South African government’s attempts to suppress press coverage of these stories for fear of the political ‘fall-out’ that the matter might cause amongst the white electorate and in case it jeopardised secret negotiations to secure the release of the prisoners; and second, it uncovers the role played by intermediaries, especially the International Committee of the Red Cross (ICRC), in the sensitive and fraught negotiation process. It will be shown that the South African authorities adopted divergent approaches when dealing with SWAPO and the Angolans/Cubans to secure the release of prisoners of war (POWs). This is because the South African authorities regarded the former as involved in an internal insurrection whereas the latter were members of the military forces of sovereign states. Accordingly, they paid lip service to the Geneva Conventions in the case of Angolan and Cuban POWs but treated captured SWAPO cadres as ‘terrorists’ or ‘criminals’.
- Full Text:
- Date Issued: 2012
The syntheses and photophysical properties of 4, 4′-isopropylidendioxydiphenyl substituted ball-type dinuclear Mg (II) and Zn (II) phthalocyanines
- Canlıca, Mevlüde, Nyokong, Tebello
- Authors: Canlıca, Mevlüde , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243554 , vital:51163 , xlink:href="https://doi.org/10.1016/j.poly.2011.10.024"
- Description: The syntheses of ball-type dinuclear Zn(II) and Mg(II) phthalocyanines containing four 4,4′-isopropylidendioxydiphenyl substituents at the peripheral and non-peripheral positions are presented. The structures of the synthesized compounds were characterized using elemental analyses, and UV–Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values were 0.14, 0.11, 0.22, 0.15 and ΦT values were 0.84, 0.88, 0.62, 0.74, for 6–9, respectively. The largest triplet yields were observed for the non-peripherally substituted complexes 6 and 7, showing that non-peripheral substitution favors increased population of the triplet state. All complexes showed reasonably long triplet lifetimes with τT 510, 310, 910 and 350 μs in DMSO, respectively.
- Full Text:
- Date Issued: 2012
- Authors: Canlıca, Mevlüde , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243554 , vital:51163 , xlink:href="https://doi.org/10.1016/j.poly.2011.10.024"
- Description: The syntheses of ball-type dinuclear Zn(II) and Mg(II) phthalocyanines containing four 4,4′-isopropylidendioxydiphenyl substituents at the peripheral and non-peripheral positions are presented. The structures of the synthesized compounds were characterized using elemental analyses, and UV–Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values were 0.14, 0.11, 0.22, 0.15 and ΦT values were 0.84, 0.88, 0.62, 0.74, for 6–9, respectively. The largest triplet yields were observed for the non-peripherally substituted complexes 6 and 7, showing that non-peripheral substitution favors increased population of the triplet state. All complexes showed reasonably long triplet lifetimes with τT 510, 310, 910 and 350 μs in DMSO, respectively.
- Full Text:
- Date Issued: 2012
The synthesis, photophysical and dielectric properties of ball-type dinuclear zinc phthalocyanine
- Canlıca, Mevlüde, Altındal, Ahmet, Nyokong, Tebello
- Authors: Canlıca, Mevlüde , Altındal, Ahmet , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243532 , vital:51161 , xlink:href="https://doi.org/10.1142/S1088424612500836"
- Description: The synthesis of ball-type dinuclear Zn(II) phthalocyanine containing four 4,4′-(9H-fluorene-9,9-diyl)diphenol substituents at the non-peripheral position is presented. The structure of the synthesized compound was characterized using elemental analyzes, and UV-vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF value was 0.16 and ΦT value was 0.72. The complex showed reasonably long triplet lifetimes with τT 7210 μs in DMSO. The frequency and temperature dependence of the dielectric properties of ZnPc were also investigated in the frequency range of 40–105 Hz and in the temperature range of 300–440 °K. It has been observed that both dielectric constant ε′ and dielectric loss ε″ decrease with the rise in frequency as they increase with the rise in temperature. The decrease in ε′ with increasing frequency is attributed to the fact that as the frequency increases, the polarizability contribution from orientation sources decreases and finally disappears.
- Full Text:
- Date Issued: 2012
- Authors: Canlıca, Mevlüde , Altındal, Ahmet , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243532 , vital:51161 , xlink:href="https://doi.org/10.1142/S1088424612500836"
- Description: The synthesis of ball-type dinuclear Zn(II) phthalocyanine containing four 4,4′-(9H-fluorene-9,9-diyl)diphenol substituents at the non-peripheral position is presented. The structure of the synthesized compound was characterized using elemental analyzes, and UV-vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF value was 0.16 and ΦT value was 0.72. The complex showed reasonably long triplet lifetimes with τT 7210 μs in DMSO. The frequency and temperature dependence of the dielectric properties of ZnPc were also investigated in the frequency range of 40–105 Hz and in the temperature range of 300–440 °K. It has been observed that both dielectric constant ε′ and dielectric loss ε″ decrease with the rise in frequency as they increase with the rise in temperature. The decrease in ε′ with increasing frequency is attributed to the fact that as the frequency increases, the polarizability contribution from orientation sources decreases and finally disappears.
- Full Text:
- Date Issued: 2012
The use of hot and cold high pressure homogenization to enhance the loading capacity and encapsulation efficiency of nanostructured lipid carriers for the hydrophilic antiretroviral drug, didanosine for potential administration to paediatric patients
- Kasongo, Kasongo W, Müller, Rainer H, Walker, Roderick B
- Authors: Kasongo, Kasongo W , Müller, Rainer H , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184087 , vital:44170 , xlink:href="https://doi.org/10.3109/10837450.2010.542163"
- Description: A major obstacle to the application of nanostructured lipid carriers (NLCs) as carriers for hydrophilic drugs is the limited loading capacity (LC) and encapsulation efficiency (EE) of NLCs for these molecules. The purpose of this research was to design and implement a strategy to enhance the LC and EE of NLCs for the hydrophilic drug, didanosine (DDI). DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid was reduced gradually using hot high pressure homogenization (HPH). The product obtained thereafter was added to Precirol® ATO 5 and the hot mixture was immediately dried using liquid nitrogen. The dried materials were then ground and passed through a 200 μm sieve and the solid lipid particles were dispersed in a surfactant solution and subsequently used to manufacture DDI-loaded NLCs using cold HPH. The LC and EE of NLCs for DDI manufactured using the new strategy were 3.39 ± 0.63% and 51.58 ± 1.31%, respectively, compared to 0.079 ± 0.001% and 32.45 ± 0.08%, respectively, obtained when DDI-loaded NLCs were produced using conventional hot HPH. The enhanced LC and EE for DDI make NLCs a potential technology for the oral administration of DDI to paediatric patients.
- Full Text:
- Date Issued: 2012
- Authors: Kasongo, Kasongo W , Müller, Rainer H , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184087 , vital:44170 , xlink:href="https://doi.org/10.3109/10837450.2010.542163"
- Description: A major obstacle to the application of nanostructured lipid carriers (NLCs) as carriers for hydrophilic drugs is the limited loading capacity (LC) and encapsulation efficiency (EE) of NLCs for these molecules. The purpose of this research was to design and implement a strategy to enhance the LC and EE of NLCs for the hydrophilic drug, didanosine (DDI). DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid was reduced gradually using hot high pressure homogenization (HPH). The product obtained thereafter was added to Precirol® ATO 5 and the hot mixture was immediately dried using liquid nitrogen. The dried materials were then ground and passed through a 200 μm sieve and the solid lipid particles were dispersed in a surfactant solution and subsequently used to manufacture DDI-loaded NLCs using cold HPH. The LC and EE of NLCs for DDI manufactured using the new strategy were 3.39 ± 0.63% and 51.58 ± 1.31%, respectively, compared to 0.079 ± 0.001% and 32.45 ± 0.08%, respectively, obtained when DDI-loaded NLCs were produced using conventional hot HPH. The enhanced LC and EE for DDI make NLCs a potential technology for the oral administration of DDI to paediatric patients.
- Full Text:
- Date Issued: 2012
The use of response surface methodology in the evaluation of captopril microparticles manufactured using an oil in oil solvent evaporation technique
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184221 , vital:44191 , xlink:href="https://doi.org/10.3109/02652048.2011.629744"
- Description: Captopril (CPT) microparticles were manufactured by solvent evaporation using acetone (dispersion phase) and liquid paraffin (manufacturing phase) with Eudragit® and Methocel® as coat materials. Design of experiments and response surface methodology (RSM) approaches were used to optimize the process. The microparticles were characterized based on the percent of drug released and yield, microcapsule size, entrapment efficiency and Hausner ratio. Differential scanning calorimetry (DSC), Infrared (IR) spectroscopy, scanning electron microscopy (SEM) and in vitro dissolution studies were conducted. The microcapsules were spherical, free-flowing and IR and DSC thermograms revealed that CPT was stable. The percent drug released was investigated with respect to Eudragit® RS and Methocel® K100M, Methocel® K15M concentrations and homogenizing speed. The optimal conditions for microencapsulation were 1.12 g Eudragit® RS, 0.67 g Methocel® K100M and 0.39 g Methocel® K15M at a homogenizing speed of 1643 rpm and 89% CPT was released. The value of RSM-mediated microencapsulation of CPT was elucidated.
- Full Text:
- Date Issued: 2012
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184221 , vital:44191 , xlink:href="https://doi.org/10.3109/02652048.2011.629744"
- Description: Captopril (CPT) microparticles were manufactured by solvent evaporation using acetone (dispersion phase) and liquid paraffin (manufacturing phase) with Eudragit® and Methocel® as coat materials. Design of experiments and response surface methodology (RSM) approaches were used to optimize the process. The microparticles were characterized based on the percent of drug released and yield, microcapsule size, entrapment efficiency and Hausner ratio. Differential scanning calorimetry (DSC), Infrared (IR) spectroscopy, scanning electron microscopy (SEM) and in vitro dissolution studies were conducted. The microcapsules were spherical, free-flowing and IR and DSC thermograms revealed that CPT was stable. The percent drug released was investigated with respect to Eudragit® RS and Methocel® K100M, Methocel® K15M concentrations and homogenizing speed. The optimal conditions for microencapsulation were 1.12 g Eudragit® RS, 0.67 g Methocel® K100M and 0.39 g Methocel® K15M at a homogenizing speed of 1643 rpm and 89% CPT was released. The value of RSM-mediated microencapsulation of CPT was elucidated.
- Full Text:
- Date Issued: 2012
The use of response surface methodology to evaluate the impact of level 2 SUPAC–IR changes on the in vitro release of metronidazole and ranitidine from a fixed-dose combination tablet
- King’ori, Loti D, Walker, Roderick B
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
The way forward with ecosystem-based management in tropical contexts: Reconciling with existing management systems
- Aswani, Shankar, Christie, Patrick, Muthiga, Nyawira A, Mahon, Robin, Primavera, Jurgenne H, Cramer, Lori A, Barbier, Edward B, Granek, Elise F, Kennedy, Chris J, Wolanski, Eric, Hacker, Sally
- Authors: Aswani, Shankar , Christie, Patrick , Muthiga, Nyawira A , Mahon, Robin , Primavera, Jurgenne H , Cramer, Lori A , Barbier, Edward B , Granek, Elise F , Kennedy, Chris J , Wolanski, Eric , Hacker, Sally
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422693 , vital:71969 , xlink:href="https://doi.org/10.1016/j.marpol.2011.02.014"
- Description: This paper discusses some of the challenges and opportunities that can arise when implementing ecosystem-based management (EBM) in tropical nations. EBM creates a new series of challenges, problems, and opportunities that must be considered in light of existing governance and management frameworks in a local context. The paper presents five case studies from different parts of the tropical world, including Oceania, insular and continental Southeast Asia, East Africa, and the Caribbean, which illustrate that the implementation of EBM in watershed and marine ecosystems offers a new series of challenges and opportunities for its inclusion with existing forms of environmental governance and management. The paper suggests that EBM is best thought of as an expansion of customary management (CM) and integrated coastal management (ICM), rather than a paradigm shift, and that it has certain benefits that are worth integrating into existing systems when possible. The paper concludes that the cultural and institutional context of CM as well as the experience, technical skills, and legal basis that serve ICM programs are logical platforms from which to build EBM programs. Some guidelines for creating hybrid management regimes are suggested. In sum, declining marine species and ecosystems require urgent action, necessitating utilization of existing paradigms such as ICM and CM as a foundation for building EBM.
- Full Text:
- Date Issued: 2012
- Authors: Aswani, Shankar , Christie, Patrick , Muthiga, Nyawira A , Mahon, Robin , Primavera, Jurgenne H , Cramer, Lori A , Barbier, Edward B , Granek, Elise F , Kennedy, Chris J , Wolanski, Eric , Hacker, Sally
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422693 , vital:71969 , xlink:href="https://doi.org/10.1016/j.marpol.2011.02.014"
- Description: This paper discusses some of the challenges and opportunities that can arise when implementing ecosystem-based management (EBM) in tropical nations. EBM creates a new series of challenges, problems, and opportunities that must be considered in light of existing governance and management frameworks in a local context. The paper presents five case studies from different parts of the tropical world, including Oceania, insular and continental Southeast Asia, East Africa, and the Caribbean, which illustrate that the implementation of EBM in watershed and marine ecosystems offers a new series of challenges and opportunities for its inclusion with existing forms of environmental governance and management. The paper suggests that EBM is best thought of as an expansion of customary management (CM) and integrated coastal management (ICM), rather than a paradigm shift, and that it has certain benefits that are worth integrating into existing systems when possible. The paper concludes that the cultural and institutional context of CM as well as the experience, technical skills, and legal basis that serve ICM programs are logical platforms from which to build EBM programs. Some guidelines for creating hybrid management regimes are suggested. In sum, declining marine species and ecosystems require urgent action, necessitating utilization of existing paradigms such as ICM and CM as a foundation for building EBM.
- Full Text:
- Date Issued: 2012