HPLC method for simultaneous analysis of ranitidine and metronidazole in dosage forms
- King'ori, Loti D, Walker, Roderick B
- Authors: King'ori, Loti D , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184790 , vital:44272 , xlink:href="https://doi.org/10.14233/ajchem.2014.15432"
- Description: A simple, rapid, precise and accurate stability indicating HPLC method for the simultaneous analysis of metronidazole and ranitidine in dosage forms has been developed and validated. Calibration curves for metronidazole and ranitidine exhibited linearity (R2 = 0.9995 for both compounds) over the concentration ranges investigated. The method was sensitive, selective and accurate for both compounds. Both drugs were found to be stable following acid hydrolysis studies. However, following alkali hydrolysis degradation of both compounds was observed. Furthermore metronidazole appeared to be stable following oxidative studies however ranitidine underwent complete degradation under these conditions. Both drugs were well resolved from the degradation products. The stability indicating chromatographic method has the necessary precision and accuracy for the simultaneous analysis of metronidazole and ranitidine in dosage forms.
- Full Text:
- Date Issued: 2014
- Authors: King'ori, Loti D , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184790 , vital:44272 , xlink:href="https://doi.org/10.14233/ajchem.2014.15432"
- Description: A simple, rapid, precise and accurate stability indicating HPLC method for the simultaneous analysis of metronidazole and ranitidine in dosage forms has been developed and validated. Calibration curves for metronidazole and ranitidine exhibited linearity (R2 = 0.9995 for both compounds) over the concentration ranges investigated. The method was sensitive, selective and accurate for both compounds. Both drugs were found to be stable following acid hydrolysis studies. However, following alkali hydrolysis degradation of both compounds was observed. Furthermore metronidazole appeared to be stable following oxidative studies however ranitidine underwent complete degradation under these conditions. Both drugs were well resolved from the degradation products. The stability indicating chromatographic method has the necessary precision and accuracy for the simultaneous analysis of metronidazole and ranitidine in dosage forms.
- Full Text:
- Date Issued: 2014
Improved l-cysteine electrocatalysis through a sequential drop dry technique using multi-walled carbon nanotubes and cobalt tetraaminophthalocyanine conjugates
- Nyoni, Stephen, Mugadza, Tawanda, Nyokong, Tebello
- Authors: Nyoni, Stephen , Mugadza, Tawanda , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193813 , vital:45398 , xlink:href="https://doi.org/10.1016/j.electacta.2013.10.023"
- Description: Voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy methods are used for characterization of a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs)–cobalt tetraaminophthalocyanine (CoTAPc) mixture or sequential drop dry modification technique whereby the MWCNTs are first placed on to the electrode followed by CoTAPc. The sequential drop dry CoTAPc–MWCNTs modified surface gave better catalytic responses with a catalytic rate constant of 2.2 × 105 M−1 s−1, apparent electron transfer rate constant of 0.073 cm s−1, and a limit of detection of 2.8 × 10−7 M. Scanning electrochemical microscopy (SECM) surface characterization (topography and reactivity) further gave proof the better catalytic perfomance of the sequential drop dry CoTAPc–MWCNTs modified surface.
- Full Text:
- Date Issued: 2014
- Authors: Nyoni, Stephen , Mugadza, Tawanda , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193813 , vital:45398 , xlink:href="https://doi.org/10.1016/j.electacta.2013.10.023"
- Description: Voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy methods are used for characterization of a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs)–cobalt tetraaminophthalocyanine (CoTAPc) mixture or sequential drop dry modification technique whereby the MWCNTs are first placed on to the electrode followed by CoTAPc. The sequential drop dry CoTAPc–MWCNTs modified surface gave better catalytic responses with a catalytic rate constant of 2.2 × 105 M−1 s−1, apparent electron transfer rate constant of 0.073 cm s−1, and a limit of detection of 2.8 × 10−7 M. Scanning electrochemical microscopy (SECM) surface characterization (topography and reactivity) further gave proof the better catalytic perfomance of the sequential drop dry CoTAPc–MWCNTs modified surface.
- Full Text:
- Date Issued: 2014
Incorporating surrogate species and seascape connectivity to improve marine conservation outcomes
- Olds, Andrew D, Connolly, Rod M, Pitt, Kylie, A, Paul, Maxwell S, Aswani, Shankar, Albert, Simon
- Authors: Olds, Andrew D , Connolly, Rod M , Pitt, Kylie, A , Paul, Maxwell S , Aswani, Shankar , Albert, Simon
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421912 , vital:71895 , xlink:href="https://doi.org/10.1111/cobi.12242"
- Description: Conservation focuses on maintaining biodiversity and ecosystem functioning, but gaps in our knowledge of species biology and ecological processes often impede progress. For this reason, focal species and habitats are used as surrogates for multispecies conservation, but species-based approaches are not widely adopted in marine ecosystems. Reserves in the Solomon Islands were designed on the basis of local ecological knowledge to conserve bumphead parrotfish (Bolbometopon muricatum) and to protect food security and ecosystem functioning. Bumphead parrotfish are an iconic threatened species and may be a useful surrogate for multispecies conservation. They move across tropical seascapes throughout their life history, in a pattern of habitat use that is shared with many other species. We examined their value as a conservation surrogate and assessed the importance of seascape connectivity (i.e., the physical connectedness of patches in the seascape) among reefs, mangroves, and seagrass to marine reserve performance. Reserves were designed for bumphead parrotfish, but also enhanced the abundance of other species. Integration of local ecological knowledge and seascape connectivity enhanced the abundance of 17 other harvested fish species in local reserves. This result has important implications for ecosystem functioning and local villagers because many of these species perform important ecological processes and provide the foundation for extensive subsistence fisheries. Our findings suggest greater success in maintaining and restoring marine ecosystems may be achieved when they are managed to conserve surrogate species and preserve functional seascape connections.
- Full Text:
- Date Issued: 2014
- Authors: Olds, Andrew D , Connolly, Rod M , Pitt, Kylie, A , Paul, Maxwell S , Aswani, Shankar , Albert, Simon
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421912 , vital:71895 , xlink:href="https://doi.org/10.1111/cobi.12242"
- Description: Conservation focuses on maintaining biodiversity and ecosystem functioning, but gaps in our knowledge of species biology and ecological processes often impede progress. For this reason, focal species and habitats are used as surrogates for multispecies conservation, but species-based approaches are not widely adopted in marine ecosystems. Reserves in the Solomon Islands were designed on the basis of local ecological knowledge to conserve bumphead parrotfish (Bolbometopon muricatum) and to protect food security and ecosystem functioning. Bumphead parrotfish are an iconic threatened species and may be a useful surrogate for multispecies conservation. They move across tropical seascapes throughout their life history, in a pattern of habitat use that is shared with many other species. We examined their value as a conservation surrogate and assessed the importance of seascape connectivity (i.e., the physical connectedness of patches in the seascape) among reefs, mangroves, and seagrass to marine reserve performance. Reserves were designed for bumphead parrotfish, but also enhanced the abundance of other species. Integration of local ecological knowledge and seascape connectivity enhanced the abundance of 17 other harvested fish species in local reserves. This result has important implications for ecosystem functioning and local villagers because many of these species perform important ecological processes and provide the foundation for extensive subsistence fisheries. Our findings suggest greater success in maintaining and restoring marine ecosystems may be achieved when they are managed to conserve surrogate species and preserve functional seascape connections.
- Full Text:
- Date Issued: 2014
Indigenous people's detection of rapid ecological change
- Aswani, Shankar, Laucer, Matthew
- Authors: Aswani, Shankar , Laucer, Matthew
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421926 , vital:71896 , xlink:href="https://doi.org/10.1111/cobi.12250"
- Description: When sudden catastrophic events occur, it becomes critical for coastal communities to detect and respond to environmental transformations because failure to do so may undermine overall ecosystem resilience and threaten people's livelihoods. We therefore asked how capable of detecting rapid ecological change following massive environmental disruptions local, indigenous people are. We assessed the direction and periodicity of experimental learning of people in the Western Solomon Islands after a tsunami in 2007. We compared the results of marine science surveys with local ecological knowledge of the benthos across 3 affected villages and 3 periods before and after the tsunami. We sought to determine how people recognize biophysical changes in the environment before and after catastrophic events such as earthquakes and tsunamis and whether people have the ability to detect ecological changes over short time scales or need longer time scales to recognize changes. Indigenous people were able to detect changes in the benthos over time. Detection levels differed between marine science surveys and local ecological knowledge sources over time, but overall patterns of statistically significant detection of change were evident for various habitats. Our findings have implications for marine conservation, coastal management policies, and disaster-relief efforts because when people are able to detect ecological changes, this, in turn, affects how they exploit and manage their marine resources.
- Full Text:
- Date Issued: 2014
- Authors: Aswani, Shankar , Laucer, Matthew
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421926 , vital:71896 , xlink:href="https://doi.org/10.1111/cobi.12250"
- Description: When sudden catastrophic events occur, it becomes critical for coastal communities to detect and respond to environmental transformations because failure to do so may undermine overall ecosystem resilience and threaten people's livelihoods. We therefore asked how capable of detecting rapid ecological change following massive environmental disruptions local, indigenous people are. We assessed the direction and periodicity of experimental learning of people in the Western Solomon Islands after a tsunami in 2007. We compared the results of marine science surveys with local ecological knowledge of the benthos across 3 affected villages and 3 periods before and after the tsunami. We sought to determine how people recognize biophysical changes in the environment before and after catastrophic events such as earthquakes and tsunamis and whether people have the ability to detect ecological changes over short time scales or need longer time scales to recognize changes. Indigenous people were able to detect changes in the benthos over time. Detection levels differed between marine science surveys and local ecological knowledge sources over time, but overall patterns of statistically significant detection of change were evident for various habitats. Our findings have implications for marine conservation, coastal management policies, and disaster-relief efforts because when people are able to detect ecological changes, this, in turn, affects how they exploit and manage their marine resources.
- Full Text:
- Date Issued: 2014
Indium phthalocyanine–CdSe/ZnS quantum dots nanocomposites showing size dependent and near ideal optical limiting behaviour
- Sanusi, Kayode, Nyokong, Tebello
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- Full Text:
- Date Issued: 2014
Integrating Customary Practices and Institutions into Comanagement of Small-scale Fisheries. Marine historical ecology in conservation: Applying the past to manage for the future
- Kittinger, John N, Cinner, Joshua, Aswani, Shankar, White, Alan T
- Authors: Kittinger, John N , Cinner, Joshua , Aswani, Shankar , White, Alan T
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/421940 , vital:71897 , ISBN 9780520959606
- Description: In many parts of the world, marine-resource governance systems include aspects of customary marine tenure and traditional sociocultural institutions for resource management. These practices are rooted in historical context and vary by culture and location, with place-specific practices and customs that are based on local knowledge systems. In this chapter, we review the incorporation of customary practices into contemporary management, highlighting the roles of social history, changes in customary practices, and their application in, and influence on, modern legal and policy contexts. Next, we discuss the challenges and opportunities of integrating historical management practices into modern governance systems, exploring the roles of comanagement and participatory approaches in successful “back to the future” management approaches. To conclude, we look to the future of integrated management systems and their potential to address social-ecological challenges in coastal areas that face increasing population densities and growing dependence on coastal and marine resources.
- Full Text:
- Date Issued: 2014
- Authors: Kittinger, John N , Cinner, Joshua , Aswani, Shankar , White, Alan T
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/421940 , vital:71897 , ISBN 9780520959606
- Description: In many parts of the world, marine-resource governance systems include aspects of customary marine tenure and traditional sociocultural institutions for resource management. These practices are rooted in historical context and vary by culture and location, with place-specific practices and customs that are based on local knowledge systems. In this chapter, we review the incorporation of customary practices into contemporary management, highlighting the roles of social history, changes in customary practices, and their application in, and influence on, modern legal and policy contexts. Next, we discuss the challenges and opportunities of integrating historical management practices into modern governance systems, exploring the roles of comanagement and participatory approaches in successful “back to the future” management approaches. To conclude, we look to the future of integrated management systems and their potential to address social-ecological challenges in coastal areas that face increasing population densities and growing dependence on coastal and marine resources.
- Full Text:
- Date Issued: 2014
Invasive alien species as drivers in socio-ecological systems: Local adaptations towards use of Lantana in Southern India
- Kannan, Ramesh, Shackleton, Charlie M, Shaanker, Ramanan U
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Shaanker, Ramanan U
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180932 , vital:43671 , xlink:href="https://doi.org/10.1007/s10668-013-9500-y"
- Description: Lantana camara. L (hereafter Lantana) was first introduced by the British into India in 1807 as an ornamental plant. Since then the species has spread across the length and breadth of the country. Attempts to control Lantana in India have not been successful. In this study, we analysed the use of Lantana by local communities in southern India and identified the possible causes and consequences of its use through the use of a household survey of the socio-economic profile of the user and nonuser households and an analysis of the ecological history of the communities. Communities have been using Lantana for over 25–30 years and apparently such use was not prompted by external agencies. The characteristics of user and nonuser households were similar, except that Lantana users were more literate and had a greater number of occupations per household than nonusers. Per capita income was similar between user and nonuser groups. For nonuser groups, their main income sources were from trading (44 %), wage labour (32 %) and forest resources (23 %). In contrast, the Lantana user groups substituted their loss of income from forest resources (7 %) by income from Lantana (46 %). The ecological history revealed that Lantana was adopted as a resource at a time when it was increasing in the landscape and traditional bamboo resources were in decline because of overuse by commercial enterprises and mast flowering. This change in ecological resource availability prompted a major shift in livelihoods for some in the area.
- Full Text:
- Date Issued: 2014
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Shaanker, Ramanan U
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180932 , vital:43671 , xlink:href="https://doi.org/10.1007/s10668-013-9500-y"
- Description: Lantana camara. L (hereafter Lantana) was first introduced by the British into India in 1807 as an ornamental plant. Since then the species has spread across the length and breadth of the country. Attempts to control Lantana in India have not been successful. In this study, we analysed the use of Lantana by local communities in southern India and identified the possible causes and consequences of its use through the use of a household survey of the socio-economic profile of the user and nonuser households and an analysis of the ecological history of the communities. Communities have been using Lantana for over 25–30 years and apparently such use was not prompted by external agencies. The characteristics of user and nonuser households were similar, except that Lantana users were more literate and had a greater number of occupations per household than nonusers. Per capita income was similar between user and nonuser groups. For nonuser groups, their main income sources were from trading (44 %), wage labour (32 %) and forest resources (23 %). In contrast, the Lantana user groups substituted their loss of income from forest resources (7 %) by income from Lantana (46 %). The ecological history revealed that Lantana was adopted as a resource at a time when it was increasing in the landscape and traditional bamboo resources were in decline because of overuse by commercial enterprises and mast flowering. This change in ecological resource availability prompted a major shift in livelihoods for some in the area.
- Full Text:
- Date Issued: 2014
Investigating Coral Reef Ethnobiology in The Western Solomon Islands for Enhancing Livelihood Resilience
- Authors: Aswani, Shankar
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421958 , vital:71899
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about the way people classify reefs locally and their close ecological and social relationships with these habitats. In a world in which coral reefs are increasingly threatened (Hughes et al. 2003, McClanahan et al. 2008), understanding how people perceive and use coral reefs is essential for predicting future ecological and social impacts, as well as for understanding human adaptation mechanisms to ecological change in these tropical marine ecosystems. This is particularly true for Oceanic islands, which are vulnerable socially and ecologically to deteriorating coral reefs, rising sea levels, and increasingly unpredictable climatic and geological phenomena (Lazarus 2012, McClanahan and Cinner 2012). Increasing human vulnerability to changing coral reefs, consequently, has resulted in numerous calls for comprehensive management using tools that include fishing regulations and quotas, marine protected areas (MPAs), and ecosystem-based management (EBM) for protecting coral reefs and other marine ecosystems. Other interventions, such as social safety nets, evacuation from vulnerable sites, and diversification within fisheries, have been proposed to enhance adaptive capacity, ameliorate social and economic sensitivity, and reduce exposure to changing coral reefs (Cinner et al. 2012).
- Full Text:
- Date Issued: 2014
- Authors: Aswani, Shankar
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421958 , vital:71899
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about the way people classify reefs locally and their close ecological and social relationships with these habitats. In a world in which coral reefs are increasingly threatened (Hughes et al. 2003, McClanahan et al. 2008), understanding how people perceive and use coral reefs is essential for predicting future ecological and social impacts, as well as for understanding human adaptation mechanisms to ecological change in these tropical marine ecosystems. This is particularly true for Oceanic islands, which are vulnerable socially and ecologically to deteriorating coral reefs, rising sea levels, and increasingly unpredictable climatic and geological phenomena (Lazarus 2012, McClanahan and Cinner 2012). Increasing human vulnerability to changing coral reefs, consequently, has resulted in numerous calls for comprehensive management using tools that include fishing regulations and quotas, marine protected areas (MPAs), and ecosystem-based management (EBM) for protecting coral reefs and other marine ecosystems. Other interventions, such as social safety nets, evacuation from vulnerable sites, and diversification within fisheries, have been proposed to enhance adaptive capacity, ameliorate social and economic sensitivity, and reduce exposure to changing coral reefs (Cinner et al. 2012).
- Full Text:
- Date Issued: 2014
ISSRs indicate that Chromolaena odorata invading southern Africa originates in Jamaica or Cuba
- Paterson, Iain D, Zachariades, Coastas
- Authors: Paterson, Iain D , Zachariades, Coastas
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406105 , vital:70239 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.04.005"
- Description: Two biotypes of the invasive alien plant, Chromolaena odorata (L.) R.M. King and Rob. (Asteraceae: Eupatorieae), are recognized in the plant’s introduced distribution. The Asian/West African (A/WA) biotype is present in West and Central Africa, India, Southeast Asia and Oceania, while the southern African (SA) biotype is only present in southern Africa. Biological control using insect natural enemies has been significantly more successful against the A/WA biotype than the SA biotype, suggesting that host plant incompatibility may have resulted in reduced efficacy of biological control agents in southern Africa. Inter-Simple Sequence Repeats (ISSR) were used to identify the origin of the SA biotype as Jamaica or Cuba. The data also confirm that the SA biotype is genetically distinct from the A/WA biotype and that the SA biotype is the result of a separate introduction. Biological control agents for C. odorata in southern Africa should be sourced from Jamaica and Cuba in order to avoid host plant incompatibility problems.
- Full Text:
- Date Issued: 2014
- Authors: Paterson, Iain D , Zachariades, Coastas
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406105 , vital:70239 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.04.005"
- Description: Two biotypes of the invasive alien plant, Chromolaena odorata (L.) R.M. King and Rob. (Asteraceae: Eupatorieae), are recognized in the plant’s introduced distribution. The Asian/West African (A/WA) biotype is present in West and Central Africa, India, Southeast Asia and Oceania, while the southern African (SA) biotype is only present in southern Africa. Biological control using insect natural enemies has been significantly more successful against the A/WA biotype than the SA biotype, suggesting that host plant incompatibility may have resulted in reduced efficacy of biological control agents in southern Africa. Inter-Simple Sequence Repeats (ISSR) were used to identify the origin of the SA biotype as Jamaica or Cuba. The data also confirm that the SA biotype is genetically distinct from the A/WA biotype and that the SA biotype is the result of a separate introduction. Biological control agents for C. odorata in southern Africa should be sourced from Jamaica and Cuba in order to avoid host plant incompatibility problems.
- Full Text:
- Date Issued: 2014
Lever Brothers & Unilever – a practical problem of source?
- Stack, Elizabeth M, Grenville, D P, Poole, Richard, Horn, Edward B, Harnett, Hugh N
- Authors: Stack, Elizabeth M , Grenville, D P , Poole, Richard , Horn, Edward B , Harnett, Hugh N
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/2143 , vital:20259
- Full Text:
- Date Issued: 2014
- Authors: Stack, Elizabeth M , Grenville, D P , Poole, Richard , Horn, Edward B , Harnett, Hugh N
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/2143 , vital:20259
- Full Text:
- Date Issued: 2014
Life satisfaction and education in South Africa: Investigating the role of attainment and the likelihood of education as a positional good
- Authors: Botha, Ferdi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396091 , vital:69149 , xlink:href="https://doi.org/10.1007/s11205-013-0452-2"
- Description: This paper explores various dynamics in the relationship between life satisfaction and education in South Africa using the 2008 National Income Dynamics Survey. The results indicate a strong positive association between educational attainment and individual satisfaction with life, which is true in the overall sample and for men and women. This positive relationship also holds for Black and Coloured individuals, but is insignificant in the Asian and White samples. Evidence indicates that education is a positional good, in that people who have attained more than the mean level of education in their relevant cluster are significantly more satisfied with life compared to those possessing less than the mean education.
- Full Text:
- Date Issued: 2014
- Authors: Botha, Ferdi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396091 , vital:69149 , xlink:href="https://doi.org/10.1007/s11205-013-0452-2"
- Description: This paper explores various dynamics in the relationship between life satisfaction and education in South Africa using the 2008 National Income Dynamics Survey. The results indicate a strong positive association between educational attainment and individual satisfaction with life, which is true in the overall sample and for men and women. This positive relationship also holds for Black and Coloured individuals, but is insignificant in the Asian and White samples. Evidence indicates that education is a positional good, in that people who have attained more than the mean level of education in their relevant cluster are significantly more satisfied with life compared to those possessing less than the mean education.
- Full Text:
- Date Issued: 2014
Low-cost housing developments in South Africa miss the opportunities for household level urban greening
- Shackleton, Charlie M, Hebinck, Paul, Kaoma, Humphrey, Chishaleshale, Mwale, Chinyimba, Abby, Shackleton, Sheona E, Gambiza, James, Gumbo, Davison
- Authors: Shackleton, Charlie M , Hebinck, Paul , Kaoma, Humphrey , Chishaleshale, Mwale , Chinyimba, Abby , Shackleton, Sheona E , Gambiza, James , Gumbo, Davison
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180967 , vital:43677 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.10.002"
- Description: Most developing countries of the world are experiencing large-scale migration from rural to urban areas. Many new migrants end up in low-cost or informal areas and slums with attendant environmental concerns. One dimension of improved urban sustainability is the provision of green spaces and trees. Whilst many countries have urban greening programmes for public spaces and streets, few have considered the status and potential contribution of trees from resident's own gardens. This paper reports firstly on the policy environment for urban forestry and greening in South Africa and secondly on the maintenance, use and appreciation of trees on private homesteads of residents of new and older low-income suburbs as well as informal housing areas from three small towns in South Africa. In particular we examine if the most recent centrally planned and built low-income housing schemes (called RDP suburbs in South Africa) have considered and incorporated plans or spaces for urban greenery in peoples’ homesteads. We found that broad environmental and sustainability concerns and statements are common in urban development and housing policies, but specific guidelines for implementation are generally absent. More specifically, urban forestry and tree planting are rarely mentioned in the broader land use and environmental policies other than the national forest act and subsequent regulations, but even there it is relatively superficial. In the study towns the prevalence, density and number of species of trees was lowest in the new RDP suburbs relative to the township and informal areas. Consequently, the contribution of tree products to local livelihoods was also lower in the RDP areas. Yet there were no differences in the level of appreciation of the value and intangible benefits of trees between residents from the three different suburbs. This shows that the failure to plan for and accommodate trees in new low-cost housing developments is missing an opportunity to improve overall urban sustainability and liveability and constraining the potential flows of tangible and intangible benefits to urban residents. Making opportunities for such in older suburbs is challenging because of space limitations and cost implications of retrospective provisions, but incorporation into plans for new low-cost housing development should be possible.
- Full Text:
- Date Issued: 2014
- Authors: Shackleton, Charlie M , Hebinck, Paul , Kaoma, Humphrey , Chishaleshale, Mwale , Chinyimba, Abby , Shackleton, Sheona E , Gambiza, James , Gumbo, Davison
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180967 , vital:43677 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.10.002"
- Description: Most developing countries of the world are experiencing large-scale migration from rural to urban areas. Many new migrants end up in low-cost or informal areas and slums with attendant environmental concerns. One dimension of improved urban sustainability is the provision of green spaces and trees. Whilst many countries have urban greening programmes for public spaces and streets, few have considered the status and potential contribution of trees from resident's own gardens. This paper reports firstly on the policy environment for urban forestry and greening in South Africa and secondly on the maintenance, use and appreciation of trees on private homesteads of residents of new and older low-income suburbs as well as informal housing areas from three small towns in South Africa. In particular we examine if the most recent centrally planned and built low-income housing schemes (called RDP suburbs in South Africa) have considered and incorporated plans or spaces for urban greenery in peoples’ homesteads. We found that broad environmental and sustainability concerns and statements are common in urban development and housing policies, but specific guidelines for implementation are generally absent. More specifically, urban forestry and tree planting are rarely mentioned in the broader land use and environmental policies other than the national forest act and subsequent regulations, but even there it is relatively superficial. In the study towns the prevalence, density and number of species of trees was lowest in the new RDP suburbs relative to the township and informal areas. Consequently, the contribution of tree products to local livelihoods was also lower in the RDP areas. Yet there were no differences in the level of appreciation of the value and intangible benefits of trees between residents from the three different suburbs. This shows that the failure to plan for and accommodate trees in new low-cost housing developments is missing an opportunity to improve overall urban sustainability and liveability and constraining the potential flows of tangible and intangible benefits to urban residents. Making opportunities for such in older suburbs is challenging because of space limitations and cost implications of retrospective provisions, but incorporation into plans for new low-cost housing development should be possible.
- Full Text:
- Date Issued: 2014
Optical nonlinearities and photophysicochemical behaviour of green and blue forms of lutetium bisphthalocyanines
- Sekhosana, Kutloana Edith, Amuhaya, Edith, Mack, John, Nyokong, Tebello
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
Optical nonlinearities in non-peripherally substituted pyridyloxy phthalocyanines
- Sanusi, Kayode, Antunes, Edith M, Nyokong, Tebello
- Authors: Sanusi, Kayode , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241618 , vital:50955 , xlink:href="https://doi.org/10.1039/C3DT52462K"
- Description: The optical nonlinearities of six non-peripherally-substituted pyridyloxy phthalocyanines have been studied at 532 nm using a nanosecond Z-scan technique in a dimethyl sulphoxide solution. Ring-strain effects and the absence of a metal center were found to greatly reduce the inherent high nonlinearities expected of some of these phthalocyanine complexes. Of the six molecules investigated, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyaninato lead(II) 3, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyanine 5, and 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyanine 6 were found to exhibit negligible nonlinear optical behavior, due to either the absence of asymmetry or central metal and/or the presence of a ring-strain effect. A two-photon absorption process was found to be the major contributor to the observed reverse saturable absorption (RSA) in 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyaninato lead(II) 4, 1(4)-mono-(2-pyridyloxy)phthalocyaninato lead(II) 7, and 1(4)-mono-(4-pyridyloxy)phthalocyaninato lead(II) 8, with large two-photon absorption cross-section, high hyperpolarizability and high third-order susceptibility values in the range of 4.53 × 10−43–5.33 × 10−42 cm4 s per photon, 1.61 × 10−28–1.89 × 10−27 esu and 9.73 × 10−12–7.05 × 10−11 esu respectively.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241618 , vital:50955 , xlink:href="https://doi.org/10.1039/C3DT52462K"
- Description: The optical nonlinearities of six non-peripherally-substituted pyridyloxy phthalocyanines have been studied at 532 nm using a nanosecond Z-scan technique in a dimethyl sulphoxide solution. Ring-strain effects and the absence of a metal center were found to greatly reduce the inherent high nonlinearities expected of some of these phthalocyanine complexes. Of the six molecules investigated, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyaninato lead(II) 3, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyanine 5, and 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyanine 6 were found to exhibit negligible nonlinear optical behavior, due to either the absence of asymmetry or central metal and/or the presence of a ring-strain effect. A two-photon absorption process was found to be the major contributor to the observed reverse saturable absorption (RSA) in 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyaninato lead(II) 4, 1(4)-mono-(2-pyridyloxy)phthalocyaninato lead(II) 7, and 1(4)-mono-(4-pyridyloxy)phthalocyaninato lead(II) 8, with large two-photon absorption cross-section, high hyperpolarizability and high third-order susceptibility values in the range of 4.53 × 10−43–5.33 × 10−42 cm4 s per photon, 1.61 × 10−28–1.89 × 10−27 esu and 9.73 × 10−12–7.05 × 10−11 esu respectively.
- Full Text:
- Date Issued: 2014
Photocatalytic behavior of phthalocyanine-silver nanoparticle conjugates supported on polystyrene fibers
- Khozile, Phindile, Nyokong, Tebello
- Authors: Khozile, Phindile , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189909 , vital:44946 , xlink:href="https://doi.org/10.1016/j.molcata.2014.07.031"
- Description: Herein, carbazole derivatized non-peripheral (1,(4)-tetra(carbazol-2-yloxy)phthalocyaninatozinc(II), 3-TCbZnPc) and peripheral (2,(3)-tetra(carbazol-2-yloxy)phthalocyaninato zinc(II), 4-TCbZnPc) are conjugated to silver nanoparticles and their photochemical and photophysical behavior are reported. The presence of silver nanoparticles resulted in reduced fluorescence, and increased triplet and singlet oxygen quantum yields. The conjugates were further electrospun into polystyrene fibers, and employed for the photodegradation of methyl orange. The photodegradation of methyl orange using all functionalized fibers followed first order kinetics, and was faster when the conjugates with silver nanoparticles were used. The non-peripherally substituted 3-TCbZnPc gave better photocatalytic activity compared to its peripherally substituted counterpart (4-TCbZnPc). The hybrid electrospun fibers provide great potential as active photocatalysts for degrading organic pollutants.
- Full Text:
- Date Issued: 2014
- Authors: Khozile, Phindile , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189909 , vital:44946 , xlink:href="https://doi.org/10.1016/j.molcata.2014.07.031"
- Description: Herein, carbazole derivatized non-peripheral (1,(4)-tetra(carbazol-2-yloxy)phthalocyaninatozinc(II), 3-TCbZnPc) and peripheral (2,(3)-tetra(carbazol-2-yloxy)phthalocyaninato zinc(II), 4-TCbZnPc) are conjugated to silver nanoparticles and their photochemical and photophysical behavior are reported. The presence of silver nanoparticles resulted in reduced fluorescence, and increased triplet and singlet oxygen quantum yields. The conjugates were further electrospun into polystyrene fibers, and employed for the photodegradation of methyl orange. The photodegradation of methyl orange using all functionalized fibers followed first order kinetics, and was faster when the conjugates with silver nanoparticles were used. The non-peripherally substituted 3-TCbZnPc gave better photocatalytic activity compared to its peripherally substituted counterpart (4-TCbZnPc). The hybrid electrospun fibers provide great potential as active photocatalysts for degrading organic pollutants.
- Full Text:
- Date Issued: 2014
Photophysical behavior of Zn aminophenoxy substituted phthalocyanine conjugates with carboxylic acid-coated silica nanoparticles
- Fashina, Adedayo, Antunes, Edith M, Nyokong, Tebello
- Authors: Fashina, Adedayo , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193802 , vital:45397 , xlink:href="https://doi.org/10.1016/j.molstruc.2014.04.034"
- Description: This work reports on the grafting of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally and peripherally with a 4-amino phenoxy group. The phthalocyanine dyes have free amino groups, facilitating covalent attachment of the dyes on the silica surface via amide bond formation. The surface area of the functionalized silica nanoparticles increased on conjugation but the pore volumes were reduced. The phthalocyanine functionalized silica nanoparticles showed lower fluorescence quantum yields as well as shorter triplet lifetimes compared to the free phthalocyanines in dimethyl formamide. For the non-peripherally substituted phthalocyanines increases in triplet yield quantum yields, lifetimes, and singlet oxygen quantum yields were observed.
- Full Text:
- Date Issued: 2014
- Authors: Fashina, Adedayo , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193802 , vital:45397 , xlink:href="https://doi.org/10.1016/j.molstruc.2014.04.034"
- Description: This work reports on the grafting of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally and peripherally with a 4-amino phenoxy group. The phthalocyanine dyes have free amino groups, facilitating covalent attachment of the dyes on the silica surface via amide bond formation. The surface area of the functionalized silica nanoparticles increased on conjugation but the pore volumes were reduced. The phthalocyanine functionalized silica nanoparticles showed lower fluorescence quantum yields as well as shorter triplet lifetimes compared to the free phthalocyanines in dimethyl formamide. For the non-peripherally substituted phthalocyanines increases in triplet yield quantum yields, lifetimes, and singlet oxygen quantum yields were observed.
- Full Text:
- Date Issued: 2014
Photophysical properties of a new water soluble tetra thiamine substituted zinc phthalocyanine conjugated to gold nanorods of different aspect ratios
- Mthethwa, Thandekile, Antunes, Edith M, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241583 , vital:50952 , xlink:href="https://doi.org/10.1039/C4DT00197D"
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods.
- Full Text:
- Date Issued: 2014
- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241583 , vital:50952 , xlink:href="https://doi.org/10.1039/C4DT00197D"
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods.
- Full Text:
- Date Issued: 2014
Photophysichochemical behavior of carbazole derivatized zinc phthalocyanine in the presence of ZnO microparticles and when embedded in electrospun fibers
- Khoza, Phindile, Antunes, Edith M, Nyokong, Tebello
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193860 , vital:45400 , xlink:href="https://doi.org/10.1016/j.dyepig.2013.12.019"
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively.
- Full Text:
- Date Issued: 2014
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193860 , vital:45400 , xlink:href="https://doi.org/10.1016/j.dyepig.2013.12.019"
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively.
- Full Text:
- Date Issued: 2014
Photophysicochemical behavior and antimicrobial activity of dihydroxosilicon tris (diaquaplatinum) octacarboxyphthalocyanine
- Managa, Muthumuni, Idowu, Mopelola A, Antunes, Edith M, Nyokong, Tebello
- Authors: Managa, Muthumuni , Idowu, Mopelola A , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241527 , vital:50947 , xlink:href="https://doi.org/10.1016/j.saa.2014.01.087"
- Description: Platination of dihydroxosilicon octacarboxyphthalocyanine (OH)2SiOCPc was successfully carried out to give dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine (OH)2SiOCPc(Pt)3 conjugate. Slight blue shifting of the absorption spectrum of (OH)2SiOCPc(Pt)3 was observed on conjugation with platinum. Comparative photophysicochemical behavior and antimicrobial photo-activities of (OH)2SiOCPc(Pt)3 conjugate with (OH)2SiOCPc or Pt nanoparticles revealed that the heavy atom, Pt on the periphery of the phthalocyanine significantly enhanced its singlet oxygen generation with a quantum yield of 0.56 obtained for the (OH)2SiOCPc(Pt)3 conjugate. The (OH)2SiOCPc(Pt)3 conjugate showed highest antimicrobial activity towards Candida albicans and Escherichia coli compared to (OH)2SiOCPc and Pt nanoparticles alone under illumination.
- Full Text:
- Date Issued: 2014
- Authors: Managa, Muthumuni , Idowu, Mopelola A , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241527 , vital:50947 , xlink:href="https://doi.org/10.1016/j.saa.2014.01.087"
- Description: Platination of dihydroxosilicon octacarboxyphthalocyanine (OH)2SiOCPc was successfully carried out to give dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine (OH)2SiOCPc(Pt)3 conjugate. Slight blue shifting of the absorption spectrum of (OH)2SiOCPc(Pt)3 was observed on conjugation with platinum. Comparative photophysicochemical behavior and antimicrobial photo-activities of (OH)2SiOCPc(Pt)3 conjugate with (OH)2SiOCPc or Pt nanoparticles revealed that the heavy atom, Pt on the periphery of the phthalocyanine significantly enhanced its singlet oxygen generation with a quantum yield of 0.56 obtained for the (OH)2SiOCPc(Pt)3 conjugate. The (OH)2SiOCPc(Pt)3 conjugate showed highest antimicrobial activity towards Candida albicans and Escherichia coli compared to (OH)2SiOCPc and Pt nanoparticles alone under illumination.
- Full Text:
- Date Issued: 2014
Photophysicochemical properties and TD-DFT calculations of a novel terminal alkyne substituted metal free phthalocyanine
- Yilmaz, Yusuf, Mack, John, Sönmez, Mehmet, Nyokong, Tebello
- Authors: Yilmaz, Yusuf , Mack, John , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241562 , vital:50950 , xlink:href="https://doi.org/10.1142/S1088424613501241"
- Description: The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.
- Full Text:
- Date Issued: 2014
- Authors: Yilmaz, Yusuf , Mack, John , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241562 , vital:50950 , xlink:href="https://doi.org/10.1142/S1088424613501241"
- Description: The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.
- Full Text:
- Date Issued: 2014