Young pregnant women and public health
- Macleod, Catriona I, Feltham-King, Tracey
- Authors: Macleod, Catriona I , Feltham-King, Tracey
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298572 , vital:57717 , xlink:href="https://doi.org/10.1080/09581596.2019.1573313"
- Description: In this paper, we outline a critical reparative justice/care approach to adolescent reproductive health as an alternative to the standard public health response to ‘teenage pregnancy’. Joining an increasing body of critical scholarship that calls for nuance in understanding reproduction amongst young people, we draw, in this paper, on data generated from an ethnographic study conducted in antenatal care units in an Eastern Cape township in South Africa. To illustrate the approach we propose, we home in on five case studies that highlight the variability of young women’s lives, the multiple injustices they experience, and the agency they demonstrate in negotiating their way through pregnancy and birth. Injustices evident in these cases centre on sexual violence, rape myths, education system failures, health system failures, shaming and stigmatising practices, socio-economic precariousness, absent male partners, and denial of services. We outline how the reparative justice approach that highlights repair and support for social and health injustices at the individual and collective level as well as at the material and symbolic level may be taken up to ensure reproductive justice for young pregnant women.
- Full Text:
- Date Issued: 2020
- Authors: Macleod, Catriona I , Feltham-King, Tracey
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298572 , vital:57717 , xlink:href="https://doi.org/10.1080/09581596.2019.1573313"
- Description: In this paper, we outline a critical reparative justice/care approach to adolescent reproductive health as an alternative to the standard public health response to ‘teenage pregnancy’. Joining an increasing body of critical scholarship that calls for nuance in understanding reproduction amongst young people, we draw, in this paper, on data generated from an ethnographic study conducted in antenatal care units in an Eastern Cape township in South Africa. To illustrate the approach we propose, we home in on five case studies that highlight the variability of young women’s lives, the multiple injustices they experience, and the agency they demonstrate in negotiating their way through pregnancy and birth. Injustices evident in these cases centre on sexual violence, rape myths, education system failures, health system failures, shaming and stigmatising practices, socio-economic precariousness, absent male partners, and denial of services. We outline how the reparative justice approach that highlights repair and support for social and health injustices at the individual and collective level as well as at the material and symbolic level may be taken up to ensure reproductive justice for young pregnant women.
- Full Text:
- Date Issued: 2020
From Baudelaire to Beardsley: some thoughts on Poe's beast as an indicator of the tastes and fears of nineteenth-century Europe
- Authors: Beard, Margot
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147781 , vital:38672 , https://doi.org/10.1080/00043389.2001.11876980
- Description: Charles Baudelaire (1821 1867) was one of the major influences on the French Decadent poets of the late nineteenth century whose aesthetic principles were shared, to a large extent, by a group of English poets and artists, among whom was Aubrey Beardsley (1872 1898). One of the major influences on Baude laire had been the American, Edgar Allan Poe (1809 1849), in whose short stories and poems Baudelaire had recognised a kindred spirit. Some intriguing aspects of changing nine teenth century attitudes emerge from a study of Baudelaire's 1856 translation of Poe's `The Murders in the Rue Morgue' and Beardsley's 1893 illustration to this story.
- Full Text:
- Date Issued: 2017
- Authors: Beard, Margot
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147781 , vital:38672 , https://doi.org/10.1080/00043389.2001.11876980
- Description: Charles Baudelaire (1821 1867) was one of the major influences on the French Decadent poets of the late nineteenth century whose aesthetic principles were shared, to a large extent, by a group of English poets and artists, among whom was Aubrey Beardsley (1872 1898). One of the major influences on Baude laire had been the American, Edgar Allan Poe (1809 1849), in whose short stories and poems Baudelaire had recognised a kindred spirit. Some intriguing aspects of changing nine teenth century attitudes emerge from a study of Baudelaire's 1856 translation of Poe's `The Murders in the Rue Morgue' and Beardsley's 1893 illustration to this story.
- Full Text:
- Date Issued: 2017
Developing biosensors in developing countries: South Africa as a case study
- Fogel, Ronen, Limson, Janice L
- Authors: Fogel, Ronen , Limson, Janice L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431661 , vital:72794 , xlink:href="https://doi.org/10.3390/bios6010005"
- Description: A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.
- Full Text:
- Date Issued: 2016
- Authors: Fogel, Ronen , Limson, Janice L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431661 , vital:72794 , xlink:href="https://doi.org/10.3390/bios6010005"
- Description: A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.
- Full Text:
- Date Issued: 2016
Assessment of the monkfish Lophius vomerinus resource off Namibia
- Maartens, Lima, Booth, Anthony J
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123863 , vital:35509 , https://doi.10.2989/025776101784528926
- Description: Monkfish (Lophius vomerinus and L. vaillanti) constitute a commercially important resource off Namibia. During 1998, the Lophius resource was the fourth most important commercial resource in terms of landed mass (c. 17 000 tons) and the fifth most important commercial resource in terms of export value (U$19.8 million) of the Namibian fishing sector (Ministry of Fisheries and Marine Resources, Namibia, unpublished data). Historically, monkfish constituted an important bycatch in the trawl fishery directed at hake (Merluccius spp.), but due to increasing market demand since the early 1990s, a fishery directed at monkfish and sole (Austroglossus microlepis) has developed. The Namibian Ministry of Fisheries and Marine Resources has identified the need to develop a management plan to ensure the resource’s medium and longterm sustainability (Maartens et al. 1999). Long-term resource management plans include the identification of an assessment model to represent reality so that the implications of managing the resource in future under a range of assumptions about its present status and its future dynamics (Cochrane et al. 1998) can be examined. The aim of this study was, therefore, to assess the status of at least part of the monkfish resource using a length-based cohort assessment (Jones 1979, 1984, Sparre and Venema 1998) and an age structured production model (Punt 1994, Punt and Japp 1994, Booth and Punt 1998).
- Full Text:
- Date Issued: 2010
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123863 , vital:35509 , https://doi.10.2989/025776101784528926
- Description: Monkfish (Lophius vomerinus and L. vaillanti) constitute a commercially important resource off Namibia. During 1998, the Lophius resource was the fourth most important commercial resource in terms of landed mass (c. 17 000 tons) and the fifth most important commercial resource in terms of export value (U$19.8 million) of the Namibian fishing sector (Ministry of Fisheries and Marine Resources, Namibia, unpublished data). Historically, monkfish constituted an important bycatch in the trawl fishery directed at hake (Merluccius spp.), but due to increasing market demand since the early 1990s, a fishery directed at monkfish and sole (Austroglossus microlepis) has developed. The Namibian Ministry of Fisheries and Marine Resources has identified the need to develop a management plan to ensure the resource’s medium and longterm sustainability (Maartens et al. 1999). Long-term resource management plans include the identification of an assessment model to represent reality so that the implications of managing the resource in future under a range of assumptions about its present status and its future dynamics (Cochrane et al. 1998) can be examined. The aim of this study was, therefore, to assess the status of at least part of the monkfish resource using a length-based cohort assessment (Jones 1979, 1984, Sparre and Venema 1998) and an age structured production model (Punt 1994, Punt and Japp 1994, Booth and Punt 1998).
- Full Text:
- Date Issued: 2010
Quantifying commercial catch and effort of monkfish Lophius vomerinus and L. vaillanti off Namibia
- Maartens, Lima, Booth, Anthony J
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
- Date Issued: 2010
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
- Date Issued: 2010
Problematising race for journalists: critical reflections on the South African Human Rights Commission Inquiry into media racism
- Authors: Berger, Guy
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147913 , vital:38684 , DOI: 10.1080/02560240185310081
- Description: How journalists report race and racism was at the centre of the South African Human Rights Commission (SAHRC) Inquiry into racism in the media. A critical analysis of the conceptual assumptions in the Inquiry's Final Report, however, reveals serious limitations to the enterprise. In particular the flawed conceptualisations, plus the generalised character of the findings are of little help in assisting the momentum of eradicating racism in South African media, and for linking race transformation to issues of class, gender, sexual orientation and xenophobia. This article identifies the problems as race essentialism and a relativism about what constitutes racism. It argues instead that journalists need the concept of racialisation in order to change their reporting. The argument upholds the desired role of the South African media as one that contributes to a non-racial, as opposed to a multi-racial, society.
- Full Text:
- Date Issued: 2007
- Authors: Berger, Guy
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147913 , vital:38684 , DOI: 10.1080/02560240185310081
- Description: How journalists report race and racism was at the centre of the South African Human Rights Commission (SAHRC) Inquiry into racism in the media. A critical analysis of the conceptual assumptions in the Inquiry's Final Report, however, reveals serious limitations to the enterprise. In particular the flawed conceptualisations, plus the generalised character of the findings are of little help in assisting the momentum of eradicating racism in South African media, and for linking race transformation to issues of class, gender, sexual orientation and xenophobia. This article identifies the problems as race essentialism and a relativism about what constitutes racism. It argues instead that journalists need the concept of racialisation in order to change their reporting. The argument upholds the desired role of the South African media as one that contributes to a non-racial, as opposed to a multi-racial, society.
- Full Text:
- Date Issued: 2007
First record of predation by the alien invasive freshwater fish Micropterus salmoides L.(Centrarchidae) on migrating estuarine fishes in South Africa
- Weyl, Olaf L F, Lewis, Hylton
- Authors: Weyl, Olaf L F , Lewis, Hylton
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446852 , vital:74565 , https://doi.org/10.1080/15627020.2006.11407365
- Description: This study presents results from stomach content analysis of 123 largemouth bass, Micropterus salmoides, sampled at the mouth of the fishway leading into a 3 m high weir at the tidal limit of the Kowie River, Eastern Cape Province (33°32‘39“S, 26°46‘ 52.3“E). Stomach contents from small (120–240 mm fork length, FL) and large (250–440mm FL) fish were analysed separately. Fish were the dominant prey item in small bass, followed by terrestrial insects and Potamonautes sp. In large bass, Potamonautes sp. dominated the stomach contents, while fish were less dominant and other prey items were considered incidental. Estuarine fish species, Monodactylus falciformis, and two species of the family Mugilidae, Mugil cephalus and Myxus capensis, were the most common fish prey in both size classes of M. salmoides. These results are the first evidence of the alien M. salmoides preying on these three indigenous estuarine species during their migration into fresh water.
- Full Text:
- Date Issued: 2006
- Authors: Weyl, Olaf L F , Lewis, Hylton
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446852 , vital:74565 , https://doi.org/10.1080/15627020.2006.11407365
- Description: This study presents results from stomach content analysis of 123 largemouth bass, Micropterus salmoides, sampled at the mouth of the fishway leading into a 3 m high weir at the tidal limit of the Kowie River, Eastern Cape Province (33°32‘39“S, 26°46‘ 52.3“E). Stomach contents from small (120–240 mm fork length, FL) and large (250–440mm FL) fish were analysed separately. Fish were the dominant prey item in small bass, followed by terrestrial insects and Potamonautes sp. In large bass, Potamonautes sp. dominated the stomach contents, while fish were less dominant and other prey items were considered incidental. Estuarine fish species, Monodactylus falciformis, and two species of the family Mugilidae, Mugil cephalus and Myxus capensis, were the most common fish prey in both size classes of M. salmoides. These results are the first evidence of the alien M. salmoides preying on these three indigenous estuarine species during their migration into fresh water.
- Full Text:
- Date Issued: 2006
Hierarchical rule generalisation for speaker identification in fiction books
- Glass, Kevin R, Bangay, Shaun D
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433174 , vital:72949 , https://doi.org/10.1145/1216262.1216266
- Description: This paper presents a hierarchical pattern matching and generalisation technique which is applied to the problem of locating the correct speaker of quoted speech found in fiction books. Patterns from a training set are generalised to create a small number of rules, which can be used to identify items of interest within the text. The pattern matching technique is applied to finding the Speech-Verb, Actor and Speaker of quotes found in fiction books. The technique performs well over the training data, resulting in rule-sets many times smaller than the training set, but providing very high accuracy. While the rule-set generalised from one book is less effective when applied to different books than an approach based on hand coded heuristics, performance is comparable when testing on data closely related to the training set.
- Full Text:
- Date Issued: 2006
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433174 , vital:72949 , https://doi.org/10.1145/1216262.1216266
- Description: This paper presents a hierarchical pattern matching and generalisation technique which is applied to the problem of locating the correct speaker of quoted speech found in fiction books. Patterns from a training set are generalised to create a small number of rules, which can be used to identify items of interest within the text. The pattern matching technique is applied to finding the Speech-Verb, Actor and Speaker of quotes found in fiction books. The technique performs well over the training data, resulting in rule-sets many times smaller than the training set, but providing very high accuracy. While the rule-set generalised from one book is less effective when applied to different books than an approach based on hand coded heuristics, performance is comparable when testing on data closely related to the training set.
- Full Text:
- Date Issued: 2006
'Respecting the racist’: racism at work
- Authors: Martin, Tom
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159079 , vital:40265 , https://hdl.handle.net/10520/EJC1447221
- Description: Racists can believe some pretty odd things, I'm not talking about the completely out-of-left field, lunatic fringe racists who might believe that God deems that white people have dominion over black people, or that there is a Jewish conspiracy to take over the world.
- Full Text:
- Date Issued: 2001
- Authors: Martin, Tom
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159079 , vital:40265 , https://hdl.handle.net/10520/EJC1447221
- Description: Racists can believe some pretty odd things, I'm not talking about the completely out-of-left field, lunatic fringe racists who might believe that God deems that white people have dominion over black people, or that there is a Jewish conspiracy to take over the world.
- Full Text:
- Date Issued: 2001
A Legacy Adapter Component of a 1394-Based Professional Studio Architecture
- Foss, Richard, Moses, Bob, Laubscher, Rob
- Authors: Foss, Richard , Moses, Bob , Laubscher, Rob
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427362 , vital:72433 , https://www.aes.org/e-lib/browse.cfm?elib=9853
- Description: Digital Harmony Studio is a specification for an IEEE-1394-based studio architecture for professional audio production. The specification identifies a number of device categories, including legacy adapters. Legacy adapters provide a vital link between the pro studio environments and current pro audio devices, and will typically take the form of breakout boxes exposing legacy ports. This paper describes a reference design for the first working device within the 'Legacy Adapter' category of the specification.
- Full Text:
- Date Issued: 2001
- Authors: Foss, Richard , Moses, Bob , Laubscher, Rob
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427362 , vital:72433 , https://www.aes.org/e-lib/browse.cfm?elib=9853
- Description: Digital Harmony Studio is a specification for an IEEE-1394-based studio architecture for professional audio production. The specification identifies a number of device categories, including legacy adapters. Legacy adapters provide a vital link between the pro studio environments and current pro audio devices, and will typically take the form of breakout boxes exposing legacy ports. This paper describes a reference design for the first working device within the 'Legacy Adapter' category of the specification.
- Full Text:
- Date Issued: 2001
A PCA-based modelling technique for predicting environmental suitability for organisms from presence records
- Robertson, Mark P, Caithness, N, Villet, Martin H
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
A sensitive and reliable method for the detection of lipid peroxidation in biological tissues
- Anoopkumar-Dukie, Shailendra, Walker, Roderick B, Daya, Santylal
- Authors: Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184325 , vital:44208 , xlink:href="https://doi.org/10.1211/0022357011775299"
- Description: A simple, accurate and cost effective method has been designed for the determination of lipid peroxidation in biological tissue samples. The method was a modification and improvement on existing methods available for lipid peroxidation determination. Solid-phase extraction was used to separate the thiobarbituric acid–malondialdehyde complex from thiobarbituric acidreactive substances and HPLC was performed using a C18 (Waters Spherisorb, 5 µm, 250¬4.6 mm i.d.) column to achieve isolation of the complex. The procedure was validated with respect to linearity of calibration (0.998), precision, sensitivity and limits of quantitation (1 nmol mL−1) and detection (0.5 nmol mL−1). Resorcinol was used as an external standard. The method was tested by inducing free radical generation with a known free radical generator, quinolinic acid, in rat brain homogenate. The results showed that the method presented allowed detection of lipid peroxidation products at concentrations in the nanomolar (nM) range compared with the micromolar (µM) range detected by other methods, thus rendering it suitable for use with biological samples. In addition, the modified method allowed for detection of the purified lipid peroxidation products, thus eliminating the possibility of simultaneous detection of impurities that absorb at the same wavelength.
- Full Text:
- Date Issued: 2001
- Authors: Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184325 , vital:44208 , xlink:href="https://doi.org/10.1211/0022357011775299"
- Description: A simple, accurate and cost effective method has been designed for the determination of lipid peroxidation in biological tissue samples. The method was a modification and improvement on existing methods available for lipid peroxidation determination. Solid-phase extraction was used to separate the thiobarbituric acid–malondialdehyde complex from thiobarbituric acidreactive substances and HPLC was performed using a C18 (Waters Spherisorb, 5 µm, 250¬4.6 mm i.d.) column to achieve isolation of the complex. The procedure was validated with respect to linearity of calibration (0.998), precision, sensitivity and limits of quantitation (1 nmol mL−1) and detection (0.5 nmol mL−1). Resorcinol was used as an external standard. The method was tested by inducing free radical generation with a known free radical generator, quinolinic acid, in rat brain homogenate. The results showed that the method presented allowed detection of lipid peroxidation products at concentrations in the nanomolar (nM) range compared with the micromolar (µM) range detected by other methods, thus rendering it suitable for use with biological samples. In addition, the modified method allowed for detection of the purified lipid peroxidation products, thus eliminating the possibility of simultaneous detection of impurities that absorb at the same wavelength.
- Full Text:
- Date Issued: 2001
Active learning in schools
- Lotz-Sisitka, Heila, Timmermans, Ingrid
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
An inventory of medicinal plants traded on the western boundary of the Kruger National Park, South Africa
- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181662 , vital:43756 , xlink:href="https://doi.org/10.4102/koedoe.v44i2.172"
- Description: The World Health Organisation estimates that traditional medicine still plays a vital role in the lives of 70-80 of the populations of developing countries. Approximately 20 000 tons of medicinal plants are estimated to be traded in South Africa annually, resulting in considerable pressure on the wild populations from which these plants are harvested. In 1997, a study was initiated to assess the extent of trade in medicinal plants on the western boundary of the Kruger National Park, and to determine local perceptions of the availability and values of these plants. This paper presents an inventory of the species traded, including vendors' and traders' perceptions of current availability of species and consumer demand, as well as price/kg. In Mpumalanga, 176 species were identified (71 of the vernacular names encountered in the market place), representing 69 families. In Northern Province, 70 different species were identified (84 of the vernacular names recorded in the markets), representing 40 families. Perceptions of availability of a species varied considerably, often within the same markets. Perceptions of demand tended to be more consistent, although these also sometimes varied. Although monitoring markets is an efficient means of assessing the conservation status of medicinal plants, it is important to select appropriate parameters. Markets often differ from one another, and an understanding of local conditions is crucial. For example, in the medicinal markets on the western boundary of the Kruger National Park, price/kg and market perceptions of availability of species were highly variable and would thus not provide a consistent monitoring parameter. Perceptions of demand provide an indication of current and potential pressure on a species, particularly when combined with the monitoring of species traded, and the introduction of substitutes in the market place. The size of plant parts traded could also provide useful monitoring data. It is important to identify the plants utilised locally first hand where possible, due to the variation of vernacular names from one area to another.
- Full Text:
- Date Issued: 2001
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181662 , vital:43756 , xlink:href="https://doi.org/10.4102/koedoe.v44i2.172"
- Description: The World Health Organisation estimates that traditional medicine still plays a vital role in the lives of 70-80 of the populations of developing countries. Approximately 20 000 tons of medicinal plants are estimated to be traded in South Africa annually, resulting in considerable pressure on the wild populations from which these plants are harvested. In 1997, a study was initiated to assess the extent of trade in medicinal plants on the western boundary of the Kruger National Park, and to determine local perceptions of the availability and values of these plants. This paper presents an inventory of the species traded, including vendors' and traders' perceptions of current availability of species and consumer demand, as well as price/kg. In Mpumalanga, 176 species were identified (71 of the vernacular names encountered in the market place), representing 69 families. In Northern Province, 70 different species were identified (84 of the vernacular names recorded in the markets), representing 40 families. Perceptions of availability of a species varied considerably, often within the same markets. Perceptions of demand tended to be more consistent, although these also sometimes varied. Although monitoring markets is an efficient means of assessing the conservation status of medicinal plants, it is important to select appropriate parameters. Markets often differ from one another, and an understanding of local conditions is crucial. For example, in the medicinal markets on the western boundary of the Kruger National Park, price/kg and market perceptions of availability of species were highly variable and would thus not provide a consistent monitoring parameter. Perceptions of demand provide an indication of current and potential pressure on a species, particularly when combined with the monitoring of species traded, and the introduction of substitutes in the market place. The size of plant parts traded could also provide useful monitoring data. It is important to identify the plants utilised locally first hand where possible, due to the variation of vernacular names from one area to another.
- Full Text:
- Date Issued: 2001
Behavioural interactions of predators and spawning chokka squid off South Africa: towards quantification
- Smale, Malcolm J, Sauer, Warwick H H, Roberts, Michael J
- Authors: Smale, Malcolm J , Sauer, Warwick H H , Roberts, Michael J
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123921 , vital:35516 , https://doi.10.1007/s002270100664
- Description: The interaction of a suite of predators with mating and spawning chokka squid (Loligo vulgaris reynaudii) was studied at inshore (<50 m) spawning grounds off South Africa. This study provides the first detailed records of predator–prey interactions of squids on their spawning grounds and is the first attempt to time disruptions caused by predators to the egg-laying behaviour of squids, thereby quantifying the perceived threat to the prey. The squids are focused on mate choice and reproduction while they aggregate over egg beds and they may be more vulnerable to predation than at other times. Their vulnerability to different predators in the field is examined and the tactics used against different predatory species are illustrated using recordings made with underwater video cameras. Predators recorded included two cephalopods (Octopus vulgaris and L. v. reynaudii), five teleosts (Pagellus bellotii natalensis, Spondyliosoma emarginatum, Pachymetopon aeneum, Cheimerius nufar and Pomatomus saltatrix), seven chondrichthyians (Squalus megalops, Mustelus mustelus, Carcharias taurus, Dasyatis brevicaudata, Gymnura natalensis, Poroderma africanum and P. pantherinum) and three marine mammals (Arctocephalus puscillus, Tursiops aduncus and Delphinus delphis). Analysis of behavioural interactions between predators and prey showed that predator disruption of egg laying may be quantified in terms of time. Marine mammals caused the most acute disruption, whereas other taxa had more chronic disruption effects because they spent more time on the spawning grounds. During November 1995, the suite of predators changed during the course of a 2-day period of underwater video recording, possibly because of an increase in water temperature. The hypothesis that predators would be concentrated around a spawning aggregation was tested by surveying the spawning ground using an underwater camera towed by a boat navigating with differential GPS. The results supported the hypothesis because predators were located only around the spawning sites. The serial spawning of chokka squids in recently upwelled water may reduce predation pressure. Furthermore, it may be difficult for predators to predict the specific spawning site on a particular day because squids disperse away from egg beds at night and use numerous spawning sites along the coast.
- Full Text:
- Date Issued: 2001
- Authors: Smale, Malcolm J , Sauer, Warwick H H , Roberts, Michael J
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123921 , vital:35516 , https://doi.10.1007/s002270100664
- Description: The interaction of a suite of predators with mating and spawning chokka squid (Loligo vulgaris reynaudii) was studied at inshore (<50 m) spawning grounds off South Africa. This study provides the first detailed records of predator–prey interactions of squids on their spawning grounds and is the first attempt to time disruptions caused by predators to the egg-laying behaviour of squids, thereby quantifying the perceived threat to the prey. The squids are focused on mate choice and reproduction while they aggregate over egg beds and they may be more vulnerable to predation than at other times. Their vulnerability to different predators in the field is examined and the tactics used against different predatory species are illustrated using recordings made with underwater video cameras. Predators recorded included two cephalopods (Octopus vulgaris and L. v. reynaudii), five teleosts (Pagellus bellotii natalensis, Spondyliosoma emarginatum, Pachymetopon aeneum, Cheimerius nufar and Pomatomus saltatrix), seven chondrichthyians (Squalus megalops, Mustelus mustelus, Carcharias taurus, Dasyatis brevicaudata, Gymnura natalensis, Poroderma africanum and P. pantherinum) and three marine mammals (Arctocephalus puscillus, Tursiops aduncus and Delphinus delphis). Analysis of behavioural interactions between predators and prey showed that predator disruption of egg laying may be quantified in terms of time. Marine mammals caused the most acute disruption, whereas other taxa had more chronic disruption effects because they spent more time on the spawning grounds. During November 1995, the suite of predators changed during the course of a 2-day period of underwater video recording, possibly because of an increase in water temperature. The hypothesis that predators would be concentrated around a spawning aggregation was tested by surveying the spawning ground using an underwater camera towed by a boat navigating with differential GPS. The results supported the hypothesis because predators were located only around the spawning sites. The serial spawning of chokka squids in recently upwelled water may reduce predation pressure. Furthermore, it may be difficult for predators to predict the specific spawning site on a particular day because squids disperse away from egg beds at night and use numerous spawning sites along the coast.
- Full Text:
- Date Issued: 2001
Challenges facing a community structure to implement CBNRM in the Eastern Cape, South Africa:
- Cocks, Michelle L, Dold, Anthony P, Grundy, Isla
- Authors: Cocks, Michelle L , Dold, Anthony P , Grundy, Isla
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141416 , vital:37970 , http://asq.africa.ufl.edu/files/Cocks-Dold-Grundy-Vol-5-Issue-3.pdf
- Description: In most developing countries, community based natural resource management (CBNRM) initiatives have been adopted in an attempt to address the issue of environmental sustainability. This has largely come about due to an increasing recognition of the ineffectiveness of the state to achieve such sustainability. Within the South African context, recent policies have been drafted that aim to achieve these outcomes, which strongly articulate the need for the participation of local people in the management of natural resources both within communal areas and on state-owned land. The objectives of new policies, however, are not being met in the Eastern Cape of South Africa for the following key reasons: the insufficient recognition of the impact of past historical and political upheavals experienced within the former homelands’ situation; the government’s inability to process land applications; the government’s lack of ability and capacity to implement these policies; and frustratingly high levels of hierarchy at both the local and national level. The Masakane community, a group of former farm workers from the former Ciskei homeland in South Africa, are attempting to implement CBNRM initiatives. The Masakane case study reveals the urgent need to develop, implement and enforce new institutional and managerial arrangements, because without such arrangements state policies are unlikely to be implemented at the grassroots level.
- Full Text:
- Date Issued: 2001
- Authors: Cocks, Michelle L , Dold, Anthony P , Grundy, Isla
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141416 , vital:37970 , http://asq.africa.ufl.edu/files/Cocks-Dold-Grundy-Vol-5-Issue-3.pdf
- Description: In most developing countries, community based natural resource management (CBNRM) initiatives have been adopted in an attempt to address the issue of environmental sustainability. This has largely come about due to an increasing recognition of the ineffectiveness of the state to achieve such sustainability. Within the South African context, recent policies have been drafted that aim to achieve these outcomes, which strongly articulate the need for the participation of local people in the management of natural resources both within communal areas and on state-owned land. The objectives of new policies, however, are not being met in the Eastern Cape of South Africa for the following key reasons: the insufficient recognition of the impact of past historical and political upheavals experienced within the former homelands’ situation; the government’s inability to process land applications; the government’s lack of ability and capacity to implement these policies; and frustratingly high levels of hierarchy at both the local and national level. The Masakane community, a group of former farm workers from the former Ciskei homeland in South Africa, are attempting to implement CBNRM initiatives. The Masakane case study reveals the urgent need to develop, implement and enforce new institutional and managerial arrangements, because without such arrangements state policies are unlikely to be implemented at the grassroots level.
- Full Text:
- Date Issued: 2001
Changes in the abundance of cells in the anterior pituitary gland and the possible roles of luteinizing hormone, prolactin and progesterone in the control of delayed implantation in the straw-coloured fruit bat (Eidolon helvum)
- Simbauni, J A, Bernard, Ric T F
- Authors: Simbauni, J A , Bernard, Ric T F
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447131 , vital:74586 , https://doi.org/10.1080/15627020.2001.11657115
- Description: Eidolon helvum (Megachiroptera) is a large frugivorous bat found in equatorial and tropical Africa. The reproductive cycle is characterized by a three-month period of delayed implantation and the total length of pregnancy may be as much as 10 months. A histochemical study of the gonadotrophs and mammotrophs of the anterior pituitary, in conjunction with assays of LH-like, progesterone-like and prolactin-like immunoreactivity in the plasma suggest that during delayed implantation the gonadotrophs were inactive while the mammotrophs were active and plasma PRL-like immunoreactivity high. We interpret this as indicating that, in the straw-coloured fruit bat, implantation was inhibited by high levels of prolactin and, as such, the endocrine control of delayed implantation may be quite different from that described for other mammals.
- Full Text:
- Date Issued: 2001
- Authors: Simbauni, J A , Bernard, Ric T F
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447131 , vital:74586 , https://doi.org/10.1080/15627020.2001.11657115
- Description: Eidolon helvum (Megachiroptera) is a large frugivorous bat found in equatorial and tropical Africa. The reproductive cycle is characterized by a three-month period of delayed implantation and the total length of pregnancy may be as much as 10 months. A histochemical study of the gonadotrophs and mammotrophs of the anterior pituitary, in conjunction with assays of LH-like, progesterone-like and prolactin-like immunoreactivity in the plasma suggest that during delayed implantation the gonadotrophs were inactive while the mammotrophs were active and plasma PRL-like immunoreactivity high. We interpret this as indicating that, in the straw-coloured fruit bat, implantation was inhibited by high levels of prolactin and, as such, the endocrine control of delayed implantation may be quite different from that described for other mammals.
- Full Text:
- Date Issued: 2001
Comparative photosensitised transformation of polychlorophenols with different sulphonated metallophthalocyanine complexes in aqueous medium
- Ozoemena, Kenneth, Kuznetsova, Nina, Nyokong, Tebello
- Authors: Ozoemena, Kenneth , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291520 , vital:56883 , xlink:href="https://doi.org/10.1016/S1381-1169(01)00243-6"
- Description: The relative efficiencies for the oxidation of trichlorophenol (TCP) and pentachlorophenol (PCP), sensitised by sulphonated phthalocyanine complexes containing Zn, Al, Sn and Si as central metals, were studied in aqueous solutions. For the first time, sulphonated silicon and tin phthalocyanines were synthesised and their activity towards photosensitisation of singlet oxygen and photo-oxidation of polychlorophenols was examined. The efficiency of the sensitised photo-oxidative degradation of polychlorophenols depends not only on singlet oxygen quantum yield of sensitiser, but also on its stability. The influence of substrate structure and the pH of the solution on the photo-oxidation efficiency, as well as on the sensitiser photodegradation were studied. It was found that the contribution of the Type II (singlet oxygen-mediated) mechanism to the relative efficiency of the photosensitised photo-oxidation of the phenol, decreased from phenol to p-chlorophenol, TCP and PCP, whereas Type I radical pathway increased. The results obtained for PCP give evidence that electron transfer from the excited sensitiser to the substrate in its unionised form is responsible for enhanced sensitiser photodegradation.
- Full Text:
- Date Issued: 2001
- Authors: Ozoemena, Kenneth , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291520 , vital:56883 , xlink:href="https://doi.org/10.1016/S1381-1169(01)00243-6"
- Description: The relative efficiencies for the oxidation of trichlorophenol (TCP) and pentachlorophenol (PCP), sensitised by sulphonated phthalocyanine complexes containing Zn, Al, Sn and Si as central metals, were studied in aqueous solutions. For the first time, sulphonated silicon and tin phthalocyanines were synthesised and their activity towards photosensitisation of singlet oxygen and photo-oxidation of polychlorophenols was examined. The efficiency of the sensitised photo-oxidative degradation of polychlorophenols depends not only on singlet oxygen quantum yield of sensitiser, but also on its stability. The influence of substrate structure and the pH of the solution on the photo-oxidation efficiency, as well as on the sensitiser photodegradation were studied. It was found that the contribution of the Type II (singlet oxygen-mediated) mechanism to the relative efficiency of the photosensitised photo-oxidation of the phenol, decreased from phenol to p-chlorophenol, TCP and PCP, whereas Type I radical pathway increased. The results obtained for PCP give evidence that electron transfer from the excited sensitiser to the substrate in its unionised form is responsible for enhanced sensitiser photodegradation.
- Full Text:
- Date Issued: 2001
Construction and characterization of carbon paste ultra-microelectrodes
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
Effect of oligomerization on the photochemical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001