Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique
- Zongo, S, Sanusi, Kayode, Britton, Jonathan, Mthunzi, P, Nyokong, Tebello, Maaza, M, Sahraoui, B
- Authors: Zongo, S , Sanusi, Kayode , Britton, Jonathan , Mthunzi, P , Nyokong, Tebello , Maaza, M , Sahraoui, B
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7261 , http://hdl.handle.net/10962/d1020270
- Description: We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532 nm with 10 ns, 10 Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10−10 m/W, 10−9 esu and 10−32 esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.04.031
- Full Text: false
- Date Issued: 2015
- Authors: Zongo, S , Sanusi, Kayode , Britton, Jonathan , Mthunzi, P , Nyokong, Tebello , Maaza, M , Sahraoui, B
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7261 , http://hdl.handle.net/10962/d1020270
- Description: We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532 nm with 10 ns, 10 Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10−10 m/W, 10−9 esu and 10−32 esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.04.031
- Full Text: false
- Date Issued: 2015
Sand stress as a non-determinant of habitat segregation of indigenous (Perna perna) and invasive (Mytilus galloprovincialis) mussels in South Africa
- Zardi, Gerardo I, Nicastro, Katy R, Porri, Francesca, McQuaid, Christopher D
- Authors: Zardi, Gerardo I , Nicastro, Katy R , Porri, Francesca , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6946 , http://hdl.handle.net/10962/d1011974
- Description: Periodical sand inundation influences diversity and distribution of intertidal species throughout the world. This study investigates the effect of sand stress on survival and on habitat segregation of the two dominant mussel species living in South Africa, the invasive Mytilus galloprovincialis and the indigenous Perna perna. P. perna occupies a lower intertidal zone which, monthly surveys over 1.5 years showed, is covered by sand for longer periods than the higher M. galloprovincialis zone. Despite this, when buried under sand, P. perna mortality rates were significantly higher than those of M. galloprovincialis in both laboratory and in field experiments. Under anoxic condition, P. perna mortality rates were still significantly higher than those for M. galloprovincialis, but both species died later than when exposed to sand burial, underlining the importance of the physical action of sand on mussel internal organs. When buried, both species accumulate sediments within the shell valves while still alive, but the quantities are much greater for P. perna. This suggests that P. perna gills are more severely damaged by sand abrasion and could explain its higher mortality rates. M. galloprovincialis has longer labial palps than P. perna, indicating a higher particle sorting ability and consequently explaining its lower mortality rates when exposed to sand in suspension. Habitat segregation is often explained by physiological tolerances, but in this case, such explanations fail. Although sand stress strongly affects the survival of the two species, it does not explain their vertical zonation. Contrary to our expectations, the species that is less well adapted to cope with sand stress maintains dominance in a habitat where such stress is high.
- Full Text:
- Date Issued: 2006
- Authors: Zardi, Gerardo I , Nicastro, Katy R , Porri, Francesca , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6946 , http://hdl.handle.net/10962/d1011974
- Description: Periodical sand inundation influences diversity and distribution of intertidal species throughout the world. This study investigates the effect of sand stress on survival and on habitat segregation of the two dominant mussel species living in South Africa, the invasive Mytilus galloprovincialis and the indigenous Perna perna. P. perna occupies a lower intertidal zone which, monthly surveys over 1.5 years showed, is covered by sand for longer periods than the higher M. galloprovincialis zone. Despite this, when buried under sand, P. perna mortality rates were significantly higher than those of M. galloprovincialis in both laboratory and in field experiments. Under anoxic condition, P. perna mortality rates were still significantly higher than those for M. galloprovincialis, but both species died later than when exposed to sand burial, underlining the importance of the physical action of sand on mussel internal organs. When buried, both species accumulate sediments within the shell valves while still alive, but the quantities are much greater for P. perna. This suggests that P. perna gills are more severely damaged by sand abrasion and could explain its higher mortality rates. M. galloprovincialis has longer labial palps than P. perna, indicating a higher particle sorting ability and consequently explaining its lower mortality rates when exposed to sand in suspension. Habitat segregation is often explained by physiological tolerances, but in this case, such explanations fail. Although sand stress strongly affects the survival of the two species, it does not explain their vertical zonation. Contrary to our expectations, the species that is less well adapted to cope with sand stress maintains dominance in a habitat where such stress is high.
- Full Text:
- Date Issued: 2006
Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions
- Zagal, José H, Griveau, Sophie J, Silva, Francisco, Nyokong, Tebello, Bedioui, Fethi
- Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
- Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
- Full Text: false
- Date Issued: 2010
- Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
- Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
- Full Text: false
- Date Issued: 2010
The transportability and utility of cognitive therapy in South African contexts: a review
- Authors: Young, Charles S
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6279 , http://hdl.handle.net/10962/d1008280
- Description: Cognitive therapy could be more widely promoted in South Africa given the great disparity between the need and provision of psychological therapies. Three possible objections to the promotion of cognitive therapy are considered: uncertainty surrounding the effectiveness of cognitive therapy in South African contexts; uncertainty surrounding the applicability in multicultural contexts; and suggestions that cognitive therapy is decontextualised and therefore objectionable in a country facing major social challenges. A systematic review of the literature indentified 15 outcome studies, and suggests that cognitive therapy is a viable and much-needed approach in South Africa.
- Full Text:
- Date Issued: 2009
- Authors: Young, Charles S
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6279 , http://hdl.handle.net/10962/d1008280
- Description: Cognitive therapy could be more widely promoted in South Africa given the great disparity between the need and provision of psychological therapies. Three possible objections to the promotion of cognitive therapy are considered: uncertainty surrounding the effectiveness of cognitive therapy in South African contexts; uncertainty surrounding the applicability in multicultural contexts; and suggestions that cognitive therapy is decontextualised and therefore objectionable in a country facing major social challenges. A systematic review of the literature indentified 15 outcome studies, and suggests that cognitive therapy is a viable and much-needed approach in South Africa.
- Full Text:
- Date Issued: 2009
Recent progress in the conversion of agricultural waste into functional materials
- Xhamla, Nqoro, Raymond Taziwa,Patricia Popoola
- Authors: Xhamla, Nqoro, Raymond Taziwa,Patricia Popoola
- Date: 2023
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/9238 , vital:73025
- Description: Agricultural waste is enriched with a variety of environmentally friendly materials that can potentially boost economic growth, reduce the spread of contagious diseases, and serve as a carbon-free renewable energy bioresource. Biopolymers produced from agricultural waste have a range of applications in medicine, agriculture, pharmaceutics, and industrial factories. The chemical extraction of biopolymers from biomass requires a series of alternating alkali, acid, and alkali treatments at controlled temperatures. Chemical extraction of plant-based biopolymers requires elevated temperatures (70–100°C), while for animal and sea organism-based biopolymers, moderate temperatures of 25–60°C are used. The obtained biopolymers are functionalized into various materials for application in a wide range of industries. The reported functional materials are loaded with inorganic nanomaterials, plant extracts, and organic compounds, which resulted in a synergistic effect and enhanced activity of the materials. Several researchers have synthesized biopolymers with synthetic polymers to improve their bioavailability, tensile strength, shelf life, and UV adsorption. This review article reports the extraction techniques of biopolymers from agricultural waste and their application in wound healing, water treatment, food storage, passive cooling, and cosmetics. The dearth of scientific articles on the applications of biopolymers generated from agricultural waste produced from food crops grown in Africa is a motivation for the present compilation.
- Full Text:
- Date Issued: 2023
- Authors: Xhamla, Nqoro, Raymond Taziwa,Patricia Popoola
- Date: 2023
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/9238 , vital:73025
- Description: Agricultural waste is enriched with a variety of environmentally friendly materials that can potentially boost economic growth, reduce the spread of contagious diseases, and serve as a carbon-free renewable energy bioresource. Biopolymers produced from agricultural waste have a range of applications in medicine, agriculture, pharmaceutics, and industrial factories. The chemical extraction of biopolymers from biomass requires a series of alternating alkali, acid, and alkali treatments at controlled temperatures. Chemical extraction of plant-based biopolymers requires elevated temperatures (70–100°C), while for animal and sea organism-based biopolymers, moderate temperatures of 25–60°C are used. The obtained biopolymers are functionalized into various materials for application in a wide range of industries. The reported functional materials are loaded with inorganic nanomaterials, plant extracts, and organic compounds, which resulted in a synergistic effect and enhanced activity of the materials. Several researchers have synthesized biopolymers with synthetic polymers to improve their bioavailability, tensile strength, shelf life, and UV adsorption. This review article reports the extraction techniques of biopolymers from agricultural waste and their application in wound healing, water treatment, food storage, passive cooling, and cosmetics. The dearth of scientific articles on the applications of biopolymers generated from agricultural waste produced from food crops grown in Africa is a motivation for the present compilation.
- Full Text:
- Date Issued: 2023
The dassie and the hunter: a South African meeting, by Jeff Opland: book review
- Authors: Wylie, Dan
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6125 , http://hdl.handle.net/10962/d1004709
- Description: [From the intoduction]: In this fascinating if not quite fine book Professor Opland, doyen scholar of oral poetries, treads that razor-edged line, devil of all memoirists, between humility and hubris, between open honesty and wallowing in one’s own unavoidability. David Yali-Manisi, the other half of this “South African meeting,” helps Opland out with his almost indefatigably calming, selfcontained, wise and energised presence. The relationship between these two men is an extraordinary, strangely evolving, not always smooth dance through several decades of South African history, politics, and academia. It really is ‘South African’ in the way in which it serves as lightning-rod to so many racial, personal, party-political, and literary currents in our recent past.
- Full Text:
- Date Issued: 2005
- Authors: Wylie, Dan
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6125 , http://hdl.handle.net/10962/d1004709
- Description: [From the intoduction]: In this fascinating if not quite fine book Professor Opland, doyen scholar of oral poetries, treads that razor-edged line, devil of all memoirists, between humility and hubris, between open honesty and wallowing in one’s own unavoidability. David Yali-Manisi, the other half of this “South African meeting,” helps Opland out with his almost indefatigably calming, selfcontained, wise and energised presence. The relationship between these two men is an extraordinary, strangely evolving, not always smooth dance through several decades of South African history, politics, and academia. It really is ‘South African’ in the way in which it serves as lightning-rod to so many racial, personal, party-political, and literary currents in our recent past.
- Full Text:
- Date Issued: 2005
Unconscious nobility: the animal poetry of Harold Farmer
- Authors: Wylie, Dan
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6122 , http://hdl.handle.net/10962/d1004705
- Description: I want to suggest that Harold Farmer's poetry works repeatedly in this area of ambiguity, a zone of tension triangulated, as it were, between three impulses. First : a notion (or even the fact) that a sense of community depends on 'knowing' what the 'other' is thinking or feeling, and on being able to articulate that knowledge. Second : suspecting, or even knowing, that certain reaches of the mind of the 'other' are fundamentally, and fascinatingly, unknowable - of the realm of the unconscious. And third : knowing (or just fearing or hoping) that any secure distinction between ourselves-as-humans and ourselves-as-sharing-animal-traits is artificial, or at least permeable. Hence, while Farmer's wild animals are perpetually on the brink of disappearing from sight and understanding, it is precisely that mysteriousness which attracts us, can sometimes envelop us, and even speak to us. In having spoken and been spoken to, we are somehow ennobled.
- Full Text:
- Date Issued: 2007
- Authors: Wylie, Dan
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6122 , http://hdl.handle.net/10962/d1004705
- Description: I want to suggest that Harold Farmer's poetry works repeatedly in this area of ambiguity, a zone of tension triangulated, as it were, between three impulses. First : a notion (or even the fact) that a sense of community depends on 'knowing' what the 'other' is thinking or feeling, and on being able to articulate that knowledge. Second : suspecting, or even knowing, that certain reaches of the mind of the 'other' are fundamentally, and fascinatingly, unknowable - of the realm of the unconscious. And third : knowing (or just fearing or hoping) that any secure distinction between ourselves-as-humans and ourselves-as-sharing-animal-traits is artificial, or at least permeable. Hence, while Farmer's wild animals are perpetually on the brink of disappearing from sight and understanding, it is precisely that mysteriousness which attracts us, can sometimes envelop us, and even speak to us. In having spoken and been spoken to, we are somehow ennobled.
- Full Text:
- Date Issued: 2007
The effect of sulfide on -glucosidases: implications for starch degradation in anaerobic bioreactors
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6463 , http://hdl.handle.net/10962/d1005792 , dx.doi.org/10.1016/j.chemosphere.2006.03.011
- Description: Membrane associated α-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 °C and pH optima of 8.0 for the α-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l[superscript (−1)]) resulted in the complete loss of all α-glucosidase activity in both the MR and SR. β-Glucosidase activities in our bioreactors were previously shown to be stimulated in the presence of sulfide. α-Glucosidases, in contrast, are inhibited by sulfide. This differential effect of sulfide on α-glucosidase and β-glucosidase activities is highlighted and is of crucial consequence to the respective degradation and utilization of starch and cellulose substrates in natural anaerobic environments and anaerobic bioreactors specifically designed for the accelerated digestion of wastewater sludge under biosulfidogenic conditions.
- Full Text:
- Date Issued: 2007
The effect of sulfide on -glucosidases: implications for starch degradation in anaerobic bioreactors
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6463 , http://hdl.handle.net/10962/d1005792 , dx.doi.org/10.1016/j.chemosphere.2006.03.011
- Description: Membrane associated α-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 °C and pH optima of 8.0 for the α-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l[superscript (−1)]) resulted in the complete loss of all α-glucosidase activity in both the MR and SR. β-Glucosidase activities in our bioreactors were previously shown to be stimulated in the presence of sulfide. α-Glucosidases, in contrast, are inhibited by sulfide. This differential effect of sulfide on α-glucosidase and β-glucosidase activities is highlighted and is of crucial consequence to the respective degradation and utilization of starch and cellulose substrates in natural anaerobic environments and anaerobic bioreactors specifically designed for the accelerated digestion of wastewater sludge under biosulfidogenic conditions.
- Full Text:
- Date Issued: 2007
The effect of physico-chemical parameters and chemical compounds on the activity of β-d-galactosidase (B-GAL), a marker enzyme for indicator microorganisms in water
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6470 , http://hdl.handle.net/10962/d1005800 , https://doi.org/10.1016/j.chemosphere.2007.02.050
- Description: The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6470 , http://hdl.handle.net/10962/d1005800 , https://doi.org/10.1016/j.chemosphere.2007.02.050
- Description: The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
- Full Text:
- Date Issued: 2007
Suitability of total coliform beta-D-galactosidase activity and CFU counts in monitoring faecal contamination of environmental water samples
- Wutor, V C, Togo, C A, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6477 , http://hdl.handle.net/10962/d1006165 , http://www.scielo.org.za/scielo.php?pid=S1816-79502009000100010&script=sci_arttext
- Description: Total coliforms are a group of bacteria found in high numbers in mammalian intestines; hence their presence in water indicates the possible contamination with faecal material. Total and faecal coliform counts were monitored over a period of 18 months using mFC, m-Endo and CM1046 media together with enzymatic assays on 215 environmental water samples obtained from the Eastern Cape Province of South Africa. A positive correlation, with an R2 value of 0.9393 was observed between faecal and total coliform colony units employing mFc and m-Endo media, and 0.8818 using CM1046 media. Also, a positive correlation was observed between Escherichia coli colony-forming units and β-D-galactosidase (B-GAL) activity (R2=0.8542). Overall, this study indicated that faecal contamination of environmental water samples could be monitored by measuring total coliform β-galactosidase activity and total coliform colony-forming units.
- Full Text: false
- Date Issued: 2009
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6477 , http://hdl.handle.net/10962/d1006165 , http://www.scielo.org.za/scielo.php?pid=S1816-79502009000100010&script=sci_arttext
- Description: Total coliforms are a group of bacteria found in high numbers in mammalian intestines; hence their presence in water indicates the possible contamination with faecal material. Total and faecal coliform counts were monitored over a period of 18 months using mFC, m-Endo and CM1046 media together with enzymatic assays on 215 environmental water samples obtained from the Eastern Cape Province of South Africa. A positive correlation, with an R2 value of 0.9393 was observed between faecal and total coliform colony units employing mFc and m-Endo media, and 0.8818 using CM1046 media. Also, a positive correlation was observed between Escherichia coli colony-forming units and β-D-galactosidase (B-GAL) activity (R2=0.8542). Overall, this study indicated that faecal contamination of environmental water samples could be monitored by measuring total coliform β-galactosidase activity and total coliform colony-forming units.
- Full Text: false
- Date Issued: 2009
A novel biosensor for the detection and monitoring of -d-galactosidase of faecal origin in water
- Wutor, V C, Togo, C A, Limson, Janice L, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
Comparison of the direct enzyme assay method with the membrane filtration technique in the quantification and monitoring of microbial indicator organisms - seasonal variations in the activities of coliforms and E.coli, temperature and pH
- Wutor, V C, Togo, C A, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6479 , http://hdl.handle.net/10962/d1006241
- Description: The aim of this project was to monitor variations and relationships between coliform and E. coli counts, the activities of their marker enzymes GAL and GUD, and temperature and pH over a period of 12 months in river samples obtained from the Eastern Cape, South Africa. Several polluted water samples were collected for direct coliform β-D-galactosidase (B-GAL) and Escherichia coli β-D-glucuronidase (B-GUD) assays and the membrane filtration technique. While all the samples showed enzyme activities, not all exhibited growth on CM1046 media. Variation in B-GAL activity (40%) was observed between November (highest activity month) and May (lowest activity month). The highest and lowest B-GUD activities were observed in the months of September and May/June, respectively. The sensitivity of the spectrophotometric assay method was indicated by a limit of detection (LOD) of 1 coliform forming unit (CFU)/100 mℓ and 2 CFU/100 mℓ for coliforms and E. coli, respectively. There was a significant (P < 0.05) positive correlation between E. coli counts and GUD activity (R2 = 0.8909). A correlation of R2 = 0.9151 was also observed between total coliforms and B-GAL activity, even though the CFUs were not evenly distributed. Direct enzyme assays were also shown to be more sensitive than the membrane filtration (MF) technique.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6479 , http://hdl.handle.net/10962/d1006241
- Description: The aim of this project was to monitor variations and relationships between coliform and E. coli counts, the activities of their marker enzymes GAL and GUD, and temperature and pH over a period of 12 months in river samples obtained from the Eastern Cape, South Africa. Several polluted water samples were collected for direct coliform β-D-galactosidase (B-GAL) and Escherichia coli β-D-glucuronidase (B-GUD) assays and the membrane filtration technique. While all the samples showed enzyme activities, not all exhibited growth on CM1046 media. Variation in B-GAL activity (40%) was observed between November (highest activity month) and May (lowest activity month). The highest and lowest B-GUD activities were observed in the months of September and May/June, respectively. The sensitivity of the spectrophotometric assay method was indicated by a limit of detection (LOD) of 1 coliform forming unit (CFU)/100 mℓ and 2 CFU/100 mℓ for coliforms and E. coli, respectively. There was a significant (P < 0.05) positive correlation between E. coli counts and GUD activity (R2 = 0.8909). A correlation of R2 = 0.9151 was also observed between total coliforms and B-GAL activity, even though the CFUs were not evenly distributed. Direct enzyme assays were also shown to be more sensitive than the membrane filtration (MF) technique.
- Full Text:
- Date Issued: 2007
Book review: Derek Barker: English Academic Literary Discourse in South Africa 1958-2004: A Review of 11 Academic Journals
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7044 , http://hdl.handle.net/10962/d1007386
- Description: Barker’s book concerns the evolution and publishing trajectories of South African journals devoted to English literary studies between the years 1958 (when the first such journal, English Studies in Africa, came into being) and 2004, the end-date of the survey. In other words, his work coincides with the period in South African history when apartheid’s protagonists were pushing for total political and social ascendancy through to the nation’s emergence into the arena of democratic possibility.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7044 , http://hdl.handle.net/10962/d1007386
- Description: Barker’s book concerns the evolution and publishing trajectories of South African journals devoted to English literary studies between the years 1958 (when the first such journal, English Studies in Africa, came into being) and 2004, the end-date of the survey. In other words, his work coincides with the period in South African history when apartheid’s protagonists were pushing for total political and social ascendancy through to the nation’s emergence into the arena of democratic possibility.
- Full Text:
- Date Issued: 2006
Guy Butler: 21 January 1918 - 26 April 2001
- Authors: Wright, Laurence
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7053 , http://hdl.handle.net/10962/d1007413
- Description: [From Introduction]: For much of the last twenty-five years of his life, Butler’s thought and work were not perceived to be ‘current’ at all. His poetry was hardly read (what’s new there? – neither is anyone else’s); some of it lay in manuscript or obscure little publications until the Collected Poems appeared in 1999. The autobiographies attracted a loyal following amongst a small, educated reading public. His early dramas, though they met with initial success, were stifled by the poetic idiom to which they aspired, and by the racial claustrophobia against which they fought. (Demea, Butler’s South African reworking of the Medea, made it to the boards only in 1990 – the multi-racial cast, let alone the themes, kept it in hibernation until then.) The deluge of journalism and polemic suffered the usual fate of ephemera. Until resurrected by Stephen Watson in 1990, the essays and lectures remained buried in periodicals where they could not be assessed as a totality. His inspiring teaching was a gift to his students, hardly accessible to the wider society; and above all, much of his time was spent as homo commiticus, serving on the boards and sub-committees of numerous university institutions and other organizations, some of which he founded. In his autobiography, he observed wryly of his changed status following accession to the Chair of English at Rhodes in 1951: ‘Professors are not entirely themselves. Their interest as persons decreases because they are now public personages. Much of their time is spent on committees whose function is to pick the brains of individuals without giving them credit.’ Guy Butler gave generously of his brains in such circumstances.
- Full Text:
- Date Issued: 2001
- Authors: Wright, Laurence
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7053 , http://hdl.handle.net/10962/d1007413
- Description: [From Introduction]: For much of the last twenty-five years of his life, Butler’s thought and work were not perceived to be ‘current’ at all. His poetry was hardly read (what’s new there? – neither is anyone else’s); some of it lay in manuscript or obscure little publications until the Collected Poems appeared in 1999. The autobiographies attracted a loyal following amongst a small, educated reading public. His early dramas, though they met with initial success, were stifled by the poetic idiom to which they aspired, and by the racial claustrophobia against which they fought. (Demea, Butler’s South African reworking of the Medea, made it to the boards only in 1990 – the multi-racial cast, let alone the themes, kept it in hibernation until then.) The deluge of journalism and polemic suffered the usual fate of ephemera. Until resurrected by Stephen Watson in 1990, the essays and lectures remained buried in periodicals where they could not be assessed as a totality. His inspiring teaching was a gift to his students, hardly accessible to the wider society; and above all, much of his time was spent as homo commiticus, serving on the boards and sub-committees of numerous university institutions and other organizations, some of which he founded. In his autobiography, he observed wryly of his changed status following accession to the Chair of English at Rhodes in 1951: ‘Professors are not entirely themselves. Their interest as persons decreases because they are now public personages. Much of their time is spent on committees whose function is to pick the brains of individuals without giving them credit.’ Guy Butler gave generously of his brains in such circumstances.
- Full Text:
- Date Issued: 2001
"Something rotten in this age of hope": Wesley Deintje directs The HamletMachine (Rhodes University Theatre, 28 September 2007)
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7048 , http://hdl.handle.net/10962/d1007390
- Description: Heiner Müller’s most famous play (Die Hamletmaschine, 1977) has evolved into something of a familiar war-horse for student theatre. The United States in particular has taken to the work; indeed, it was meant in part for them: “Heil Coca-cola!” says the script. For today’s South African ears this has become, very aptly, “Hail the Rainbow Nation!” What young director can resist it? Only eight pages in extent, the sparse yet densely referential text offers unfettered scope for interpretation and contextualization. Sure, the original offered Muller’s despairing take on the collapse of western civilisation, typified in the East German predicament where intellectuals felt trapped between the total failure of ‘actually existing socialism’ – that ideological mirage – in the German Democratic Republic, and the horrors of emergent bandit capitalism presaging an uncomfortable future. But the spaces in the text are so capacious that almost any claim to climactic despair can be entertained: idiot consumerism, gender oppression and aggression, political treachery and malfeasance, fascism, existential angst, intellectual cowardice, the postmodern condition, the rejection of hope.
- Full Text:
- Date Issued: 2008
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7048 , http://hdl.handle.net/10962/d1007390
- Description: Heiner Müller’s most famous play (Die Hamletmaschine, 1977) has evolved into something of a familiar war-horse for student theatre. The United States in particular has taken to the work; indeed, it was meant in part for them: “Heil Coca-cola!” says the script. For today’s South African ears this has become, very aptly, “Hail the Rainbow Nation!” What young director can resist it? Only eight pages in extent, the sparse yet densely referential text offers unfettered scope for interpretation and contextualization. Sure, the original offered Muller’s despairing take on the collapse of western civilisation, typified in the East German predicament where intellectuals felt trapped between the total failure of ‘actually existing socialism’ – that ideological mirage – in the German Democratic Republic, and the horrors of emergent bandit capitalism presaging an uncomfortable future. But the spaces in the text are so capacious that almost any claim to climactic despair can be entertained: idiot consumerism, gender oppression and aggression, political treachery and malfeasance, fascism, existential angst, intellectual cowardice, the postmodern condition, the rejection of hope.
- Full Text:
- Date Issued: 2008
Cultivating Grahamstown: Nathaniel Merriman, Shakespeare and Books
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7033 , http://hdl.handle.net/10962/d1007367
- Description: In 1857, Archdeacon Nathaniel Merriman delivered two public lectures on Shakespeare under the auspices of the “General Institute” of Grahamstown. The first, “On the Study of Shakspeare”, was given on 2 September and “Shakspeare, As Bearing on English History” two months later, on Friday 6 November. This article sets out to place the lectures in their local context, by providing a brief sketch of literary and cultural life in the town, in which the appreciation of Shakespeare played no small part.
- Full Text:
- Date Issued: 2008
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7033 , http://hdl.handle.net/10962/d1007367
- Description: In 1857, Archdeacon Nathaniel Merriman delivered two public lectures on Shakespeare under the auspices of the “General Institute” of Grahamstown. The first, “On the Study of Shakspeare”, was given on 2 September and “Shakspeare, As Bearing on English History” two months later, on Friday 6 November. This article sets out to place the lectures in their local context, by providing a brief sketch of literary and cultural life in the town, in which the appreciation of Shakespeare played no small part.
- Full Text:
- Date Issued: 2008
Guy Butler (obituary)
- Authors: Wright, Laurence
- Date: 1999
- Language: English
- Type: Article
- Identifier: vital:7052 , http://hdl.handle.net/10962/d1007411
- Description: An obituary focusing on Guy Butler's Shakespearean preoccupations. The 1999/2000 volume of Shakespeare in Southern Africa only appeared in 2001. The Butler obituary was included as a 'stop-press' item as the volume went to print, which accounts for the apparent anomaly between the date of publication and the date of Guy Butler's death.
- Full Text:
- Date Issued: 1999
- Authors: Wright, Laurence
- Date: 1999
- Language: English
- Type: Article
- Identifier: vital:7052 , http://hdl.handle.net/10962/d1007411
- Description: An obituary focusing on Guy Butler's Shakespearean preoccupations. The 1999/2000 volume of Shakespeare in Southern Africa only appeared in 2001. The Butler obituary was included as a 'stop-press' item as the volume went to print, which accounts for the apparent anomaly between the date of publication and the date of Guy Butler's death.
- Full Text:
- Date Issued: 1999
Repositioning Renaissance studies in South Africa: strategic thinking or 'business-as-usual
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006
Nathaniel Merriman's lecture: "On the study of Shakspeare".
- Authors: Wright, Laurence
- Date: 2008-09-23
- Language: English
- Type: Article
- Identifier: vital:7034 , http://hdl.handle.net/10962/d1007368
- Description: Nathaniel Merriman’s lectures on Shakespeare were published in 1857 and 1858. The first, “On the Study of Shakspeare,” was delivered in the Court House, Grahamstown on the 2nd September 1857 to an audience of more than four hundred and fifty people. The second, “Shakspeare, as Bearing on English History,” was given in the same venue two months later, on Friday, 6 November 1857, and was also well attended. The lectures were published under the auspices of the Committee of “The General Institute,” which sponsored the lectures, and printed at the Anglo-African Office in the High Street. The two lectures and their context are little known in Shakespeare studies because the original pamphlets are rare. The first lecture appears in Mendelssohn’s South African Bibliography (1910), while the second is picked up only in the 1979 revision of that work. Copies of “On the Study of Shakspeare” are held by the Mendelssohn Library in the Library of Parliament, Cape Town; by The South African Library, Cape Town; and in the Oppenheimer Collection, Johannesburg. Copies of “Shakspeare, as Bearing on English History” are held by the Mendelssohn Library; by the University of the Witwatersrand Library, Johannesburg; and by the Kimberley Public Library. The purpose of preparing annotated editions of these lectures is to make them more accessible to scholars and draw them further into the mainstream of international discussion on colonial Shakespeare.
- Full Text:
- Authors: Wright, Laurence
- Date: 2008-09-23
- Language: English
- Type: Article
- Identifier: vital:7034 , http://hdl.handle.net/10962/d1007368
- Description: Nathaniel Merriman’s lectures on Shakespeare were published in 1857 and 1858. The first, “On the Study of Shakspeare,” was delivered in the Court House, Grahamstown on the 2nd September 1857 to an audience of more than four hundred and fifty people. The second, “Shakspeare, as Bearing on English History,” was given in the same venue two months later, on Friday, 6 November 1857, and was also well attended. The lectures were published under the auspices of the Committee of “The General Institute,” which sponsored the lectures, and printed at the Anglo-African Office in the High Street. The two lectures and their context are little known in Shakespeare studies because the original pamphlets are rare. The first lecture appears in Mendelssohn’s South African Bibliography (1910), while the second is picked up only in the 1979 revision of that work. Copies of “On the Study of Shakspeare” are held by the Mendelssohn Library in the Library of Parliament, Cape Town; by The South African Library, Cape Town; and in the Oppenheimer Collection, Johannesburg. Copies of “Shakspeare, as Bearing on English History” are held by the Mendelssohn Library; by the University of the Witwatersrand Library, Johannesburg; and by the Kimberley Public Library. The purpose of preparing annotated editions of these lectures is to make them more accessible to scholars and draw them further into the mainstream of international discussion on colonial Shakespeare.
- Full Text:
Can formal language planning link to grassroots cultural initiatives?: an informal investigation
- Authors: Wright, Laurence
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:7041 , http://hdl.handle.net/10962/d1007381
- Description: Formal language planning is inevitably a top-down, highly technical process. Success for such planning would seem to depend on engaging productively with existing or readily developed social motivation within the society. This article reports on an informal investigation into how ordinary language practitioners and cultural workers in South Africa view the possibilities of contributing to the country’s emerging language dispensation, what they regard as their most useful possible contributions, and what they expect from the language planners and ‘government’ in support of South Africa’s Language Policy and Plan.
- Full Text:
- Date Issued: 2002
- Authors: Wright, Laurence
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:7041 , http://hdl.handle.net/10962/d1007381
- Description: Formal language planning is inevitably a top-down, highly technical process. Success for such planning would seem to depend on engaging productively with existing or readily developed social motivation within the society. This article reports on an informal investigation into how ordinary language practitioners and cultural workers in South Africa view the possibilities of contributing to the country’s emerging language dispensation, what they regard as their most useful possible contributions, and what they expect from the language planners and ‘government’ in support of South Africa’s Language Policy and Plan.
- Full Text:
- Date Issued: 2002