Using a unified invasion framework to characterize Africa’s first loricariid catfish invasion
- Jones, Roy W, Weyl, Olaf L F, Hill, Martin P, Swartz, Ernest R
- Authors: Jones, Roy W , Weyl, Olaf L F , Hill, Martin P , Swartz, Ernest R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418081 , vital:71507 , xlink:href="https://doi.org/10.1007/s10530-013-0438-7"
- Description: This paper presents evidence of establishment of a loricariid population in the Nseleni River in South Africa and uses a unified framework to determine its invasion stage. Specimens were identified morphologically as Pterygioplichthys disjunctivus (Weber 1991), but genetic barcoding results indicated close association with specimens that may have a hybrid history. The species was introduced into South Africa via the pet trade and the first record of introduction into the wild was in 2004. Samples collected in 2011 and 2012 demonstrated that there were multiple length cohorts in the population including juveniles (12–130 mm total length TL) and large (>300 mm TL) adult fish. Gonadal assessment of adults demonstrated the presence of reproduction capable specimens. The concurrent occurrence of mature adults and juvenile fish demonstrated establishment. Locality records indicate that P. disjunctivus has already spread between two rivers through an inter basin water transfer. Using a unified framework for invasions this invasion was categorized as a self-sustaining population in the wild with individuals surviving and reproducing a significant distance from their original point of introduction. Containment is suggested as potential management strategy.
- Full Text:
- Date Issued: 2013
- Authors: Jones, Roy W , Weyl, Olaf L F , Hill, Martin P , Swartz, Ernest R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418081 , vital:71507 , xlink:href="https://doi.org/10.1007/s10530-013-0438-7"
- Description: This paper presents evidence of establishment of a loricariid population in the Nseleni River in South Africa and uses a unified framework to determine its invasion stage. Specimens were identified morphologically as Pterygioplichthys disjunctivus (Weber 1991), but genetic barcoding results indicated close association with specimens that may have a hybrid history. The species was introduced into South Africa via the pet trade and the first record of introduction into the wild was in 2004. Samples collected in 2011 and 2012 demonstrated that there were multiple length cohorts in the population including juveniles (12–130 mm total length TL) and large (>300 mm TL) adult fish. Gonadal assessment of adults demonstrated the presence of reproduction capable specimens. The concurrent occurrence of mature adults and juvenile fish demonstrated establishment. Locality records indicate that P. disjunctivus has already spread between two rivers through an inter basin water transfer. Using a unified framework for invasions this invasion was categorized as a self-sustaining population in the wild with individuals surviving and reproducing a significant distance from their original point of introduction. Containment is suggested as potential management strategy.
- Full Text:
- Date Issued: 2013
Exploring a systems approach to mainstreaming sustainability in universities: A case study of Rhodes University in South Africa
- Togo, Muchaiteyi, Lotz-Sisitka, Heila
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013
Design and evaluation of an electrochemical immunosensor for measles serodiagnosis using measles-specific Immunoglobulin G antibodies
- Mashazi, Philani N, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
Fluorescence “turn on” probe for bromide ion using nanoconjugates of glutathione-capped CdTe@ ZnS quantum dots with nickel tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190479 , vital:44998 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.05.013"
- Description: In this paper, three differently sized glutathione (GSH)-capped CdTe@ZnS quantum dots (QDs) have been successfully conjugated to nickel tetraamino-phthalocyanine (NiTAPc) to form different QDs-NiTAPc nanocomplexes. Several techniques such as TEM, FT-IR, time-resolved fluorescence measurement and electronic spectroscopy were employed to characterize the nanocomplex. Bromide ion was chosen as a model anion to test the efficacy of the nanoprobe. The fluorescence of the nanoconjugate was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion. Experimental results showed that the quantum size effect of nanocrystal QD determined the overall sensitivity and selectivity of the nanoprobe and followed the order QD563-NiTAPc > QD605-NiTAPc > QD621-NiTAPc. The mechanism of reaction is proposed.
- Full Text:
- Date Issued: 2013
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190479 , vital:44998 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.05.013"
- Description: In this paper, three differently sized glutathione (GSH)-capped CdTe@ZnS quantum dots (QDs) have been successfully conjugated to nickel tetraamino-phthalocyanine (NiTAPc) to form different QDs-NiTAPc nanocomplexes. Several techniques such as TEM, FT-IR, time-resolved fluorescence measurement and electronic spectroscopy were employed to characterize the nanocomplex. Bromide ion was chosen as a model anion to test the efficacy of the nanoprobe. The fluorescence of the nanoconjugate was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion. Experimental results showed that the quantum size effect of nanocrystal QD determined the overall sensitivity and selectivity of the nanoprobe and followed the order QD563-NiTAPc > QD605-NiTAPc > QD621-NiTAPc. The mechanism of reaction is proposed.
- Full Text:
- Date Issued: 2013
Nutrient-mediated effects on Cornops aquaticum Brüner (Orthoptera: Acrididae), a potential biological control agent of water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae)
- Bownes, Angela, Hill, Martin P, Byrne, Marcus J
- Authors: Bownes, Angela , Hill, Martin P , Byrne, Marcus J
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406131 , vital:70241 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Environmental nutrient availability can drive and modify both plant responses to herbivory by phytophagous insects and insect feeding patterns which, in insect-weed systems, may ultimately determine whether biological control succeeds or fails. The impacts of insect biological control agents on the invasive aquatic weed, water hyacinth (Eichhornia crassipes) vary with nutrient levels in the environment. It was therefore considered important to evaluate nutrient-specific responses of E. crassipes to a grasshopper herbivore, Cornops aquaticum, prior to its release in South Africa. Both plant productivity and the response of E. crassipes to herbivory by C. aquaticum were nutrient dependent. Increases in plant biomass and leaf and ramet production were correlated with increases in nutrients in the water and plant biomass accumulation was reduced by herbivory at all three nutrient levels tested (high = 67%; medium = 100%; low = 400%). C. aquaticum nymphs fed E. crassipes leaves with the lowest nitrogen levels produced the highest biomass of frass during their development, indicating compensatory consumption. The results suggest that environmental nutrient availability will influence efficacy of C. aquaticum. They also provide further evidence that E. crassipes problems are exacerbated by an over-abundance of nutrients in aquatic environments, and that biological control would be a highly effective management tool if aquatic systems in South Africa were less polluted. Additionally, the results also show how an understanding of the fundamental responses of E. crassipes and its insect biocontrol agents to their environment can assist in determining specific management strategies or interventions according to prevailing site-specific conditions.
- Full Text:
- Date Issued: 2013
- Authors: Bownes, Angela , Hill, Martin P , Byrne, Marcus J
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406131 , vital:70241 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Environmental nutrient availability can drive and modify both plant responses to herbivory by phytophagous insects and insect feeding patterns which, in insect-weed systems, may ultimately determine whether biological control succeeds or fails. The impacts of insect biological control agents on the invasive aquatic weed, water hyacinth (Eichhornia crassipes) vary with nutrient levels in the environment. It was therefore considered important to evaluate nutrient-specific responses of E. crassipes to a grasshopper herbivore, Cornops aquaticum, prior to its release in South Africa. Both plant productivity and the response of E. crassipes to herbivory by C. aquaticum were nutrient dependent. Increases in plant biomass and leaf and ramet production were correlated with increases in nutrients in the water and plant biomass accumulation was reduced by herbivory at all three nutrient levels tested (high = 67%; medium = 100%; low = 400%). C. aquaticum nymphs fed E. crassipes leaves with the lowest nitrogen levels produced the highest biomass of frass during their development, indicating compensatory consumption. The results suggest that environmental nutrient availability will influence efficacy of C. aquaticum. They also provide further evidence that E. crassipes problems are exacerbated by an over-abundance of nutrients in aquatic environments, and that biological control would be a highly effective management tool if aquatic systems in South Africa were less polluted. Additionally, the results also show how an understanding of the fundamental responses of E. crassipes and its insect biocontrol agents to their environment can assist in determining specific management strategies or interventions according to prevailing site-specific conditions.
- Full Text:
- Date Issued: 2013
Characterization of bioflocculants produced by consortia of three marine bacteria belonging to the genera bacillus and cobetia previously isolated from the bottom sediment of Algoa Bay in the Eastern Cape Province of South Africa
- Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Comparative phototransformation of environmental pollutants using metallophthalocyanines supported on electrospun polymer fibers
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190509 , vital:45001 , xlink:href="https://doi.org/10.1002/app.38381"
- Description: The fluorescence and photoactivity of a series of Zn and Lu phthalocyanine complexes incorporated in various polymer fibers were investigated for the phototransformation of 4-chlorophenol, 4-nitrophenol, and methyl orange. The phthalocyanine complexes functionalized on polystyrene and polysulfone polymer fibers could be applied in the degradation of 4-chlorophenol, 4-nitrophenol, and methyl orange with 4-chlorophenol being much more susceptible to degradation while methyl orange was the least. Also polymer fibers of polystyrene were found to be reusable.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190509 , vital:45001 , xlink:href="https://doi.org/10.1002/app.38381"
- Description: The fluorescence and photoactivity of a series of Zn and Lu phthalocyanine complexes incorporated in various polymer fibers were investigated for the phototransformation of 4-chlorophenol, 4-nitrophenol, and methyl orange. The phthalocyanine complexes functionalized on polystyrene and polysulfone polymer fibers could be applied in the degradation of 4-chlorophenol, 4-nitrophenol, and methyl orange with 4-chlorophenol being much more susceptible to degradation while methyl orange was the least. Also polymer fibers of polystyrene were found to be reusable.
- Full Text:
- Date Issued: 2013
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
Morphological and genetic characterization of a South African Plutella xylostella granulovirus (plxy GV) isolate
- Abdulkadir, Fatima, Marsberg, Tamryn, Knox, Caroline M, Hill, Martin P, Moore, Sean D
- Authors: Abdulkadir, Fatima , Marsberg, Tamryn , Knox, Caroline M , Hill, Martin P , Moore, Sean D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406117 , vital:70240 , xlink:href="https://hdl.handle.net/10520/EJC132828"
- Description: Plutella xylostella (L.) (Lepidoptera: Plutellidae), also known as diamondback moth, is a destructive insect pest of cruciferous crops (Talekar and Shelton 1993; Shelton 2004). The pest occurs wherever its host plants are cultivated and the global annual cost of damage and control is estimated to be US$4-5 billion (Zalucki et al. 2012). The extensive use of synthetic pesticides for control combined with the high fecundity of P. xylostella has resulted in the pest developing resistance to nearly all classes of insecticides (Grzywacz et al. 2009). Moreover, these chemicals have negative environmental implications and may affect non-target species, some of which are natural enemies of the pest.
- Full Text:
- Date Issued: 2013
- Authors: Abdulkadir, Fatima , Marsberg, Tamryn , Knox, Caroline M , Hill, Martin P , Moore, Sean D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406117 , vital:70240 , xlink:href="https://hdl.handle.net/10520/EJC132828"
- Description: Plutella xylostella (L.) (Lepidoptera: Plutellidae), also known as diamondback moth, is a destructive insect pest of cruciferous crops (Talekar and Shelton 1993; Shelton 2004). The pest occurs wherever its host plants are cultivated and the global annual cost of damage and control is estimated to be US$4-5 billion (Zalucki et al. 2012). The extensive use of synthetic pesticides for control combined with the high fecundity of P. xylostella has resulted in the pest developing resistance to nearly all classes of insecticides (Grzywacz et al. 2009). Moreover, these chemicals have negative environmental implications and may affect non-target species, some of which are natural enemies of the pest.
- Full Text:
- Date Issued: 2013
The development of catalytic oxovanadium (IV)-containing microspheres for the oxidation of various organosulfur compounds
- Ogunlaja, Adeniyi S, Khene, Samson M, Antunes, Edith M, Nyokong, Tebello, Torto, Nelson, Tshentu, Zenixole R
- Authors: Ogunlaja, Adeniyi S , Khene, Samson M , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241783 , vital:50969 , xlink:href="https://doi.org/10.1016/j.apcata.2013.05.004"
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil.
- Full Text:
- Date Issued: 2013
- Authors: Ogunlaja, Adeniyi S , Khene, Samson M , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241783 , vital:50969 , xlink:href="https://doi.org/10.1016/j.apcata.2013.05.004"
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil.
- Full Text:
- Date Issued: 2013
Impacts of a sub-lethal dose of glyphosate on water hyacinth nutrients and its indirect effects on Neochetina weevils
- Katembo, Naweji, Hill, Martin P, Byrne, Marcus J
- Authors: Katembo, Naweji , Hill, Martin P , Byrne, Marcus J
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417726 , vital:71481 , xlink:href="https://doi.org/10.1080/09583157.2013.839982"
- Description: A sub-lethal dose of a herbicide under field conditions was applied to determine if it stimulates an increase in water hyacinth nutrients, thereby increasing feeding intensity by Neochetina spp. weevils used as biocontrol agents of the weed. Nitrogen (N) and carbon (C) were measured and compared between sprayed plants and control plants. At one site (Delta Park), N levels were lower in the sprayed plants compared to the control plants both in the leaves and the crown. At the second site (Farm Dam), leaf N was also lower in the sprayed plants than in the control plants, while no difference was found in crown N. Mean number of feeding scars per cm2 at Delta Park was significantly higher on the sprayed plants compared to the control plants, while no significant difference was found at Farm Dam. At Delta Park, there was no correlation, however, between the number of weevil feeding scars and leaf N or C:N ratio in sprayed plants. In conclusion, the sub-lethal dose of glyphosate did not directly result in an increase in weevil feeding intensity but it can be recommended in an integrated control system to retard water hyacinth growth while conserving the weevil population.
- Full Text:
- Date Issued: 2013
- Authors: Katembo, Naweji , Hill, Martin P , Byrne, Marcus J
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417726 , vital:71481 , xlink:href="https://doi.org/10.1080/09583157.2013.839982"
- Description: A sub-lethal dose of a herbicide under field conditions was applied to determine if it stimulates an increase in water hyacinth nutrients, thereby increasing feeding intensity by Neochetina spp. weevils used as biocontrol agents of the weed. Nitrogen (N) and carbon (C) were measured and compared between sprayed plants and control plants. At one site (Delta Park), N levels were lower in the sprayed plants compared to the control plants both in the leaves and the crown. At the second site (Farm Dam), leaf N was also lower in the sprayed plants than in the control plants, while no difference was found in crown N. Mean number of feeding scars per cm2 at Delta Park was significantly higher on the sprayed plants compared to the control plants, while no significant difference was found at Farm Dam. At Delta Park, there was no correlation, however, between the number of weevil feeding scars and leaf N or C:N ratio in sprayed plants. In conclusion, the sub-lethal dose of glyphosate did not directly result in an increase in weevil feeding intensity but it can be recommended in an integrated control system to retard water hyacinth growth while conserving the weevil population.
- Full Text:
- Date Issued: 2013
Stock returns and Friday the 13th effect in five African countries
- Authors: Botha, Ferdi
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396127 , vital:69152 , xlink:href="https://www.ajol.info/index.php/aref/article/view/91060"
- Description: This study is concerned with Friday the 13th and daily stock market returns in five African countries. Using the MSCI Global Equity Indices during various periods, the evidence overwhelmingly suggests that there is no Friday the 13th effect.
- Full Text:
- Date Issued: 2013
- Authors: Botha, Ferdi
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396127 , vital:69152 , xlink:href="https://www.ajol.info/index.php/aref/article/view/91060"
- Description: This study is concerned with Friday the 13th and daily stock market returns in five African countries. Using the MSCI Global Equity Indices during various periods, the evidence overwhelmingly suggests that there is no Friday the 13th effect.
- Full Text:
- Date Issued: 2013
The challenges of alleviating poverty through ecological restoration: Insights from South Africa's “working for water” program
- McConnachie, Matthew M, Cowling, Richard M, Shackleton, Charlie M, Knight, Andrew T
- Authors: McConnachie, Matthew M , Cowling, Richard M , Shackleton, Charlie M , Knight, Andrew T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181003 , vital:43680 , xlink:href="https://doi.org/10.1111/rec.12038"
- Description: Public works programs have been posited as win–win solutions for achieving societal goals for ecological restoration and poverty alleviation. However, little is documented regarding the challenges of implementing such projects. A commonly cited example is South Africa's invasive alien plant control program “Working for Water” (WfW), which aims to create employment via restoring landscapes invaded with alien plants. Recent studies have raised questions over the effectiveness of this program in achieving both its restoration and poverty alleviation goals. This is the first study that we are aware of that synthesizes the knowledge of managers on both the poverty alleviation and environmental outcomes of a public works project. Herein, we sought to understand the challenges and constraints faced by 23 WfW managers in fulfilling the program's environmental and poverty alleviation objectives. We found that the challenges most frequently cited by managers related to the capacity and competence of managers and teams, followed by challenges relating to planning and coordination, specifically the challenges of being flexible and adaptive when constrained by operating procedures. In addition, the current focus on maximizing short-term employment was perceived by some as limiting the efficiency and long-term effectiveness of the WfW program in achieving its environmental and social goals. We suggest that improving the conditions and duration of employment could improve the effectiveness of invasive alien plant control and ecological outcomes. We also suggest that WfW measure the impacts of their interventions through an adaptive management approach so that it can learn and adapt to the challenges it faces.
- Full Text:
- Date Issued: 2013
- Authors: McConnachie, Matthew M , Cowling, Richard M , Shackleton, Charlie M , Knight, Andrew T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181003 , vital:43680 , xlink:href="https://doi.org/10.1111/rec.12038"
- Description: Public works programs have been posited as win–win solutions for achieving societal goals for ecological restoration and poverty alleviation. However, little is documented regarding the challenges of implementing such projects. A commonly cited example is South Africa's invasive alien plant control program “Working for Water” (WfW), which aims to create employment via restoring landscapes invaded with alien plants. Recent studies have raised questions over the effectiveness of this program in achieving both its restoration and poverty alleviation goals. This is the first study that we are aware of that synthesizes the knowledge of managers on both the poverty alleviation and environmental outcomes of a public works project. Herein, we sought to understand the challenges and constraints faced by 23 WfW managers in fulfilling the program's environmental and poverty alleviation objectives. We found that the challenges most frequently cited by managers related to the capacity and competence of managers and teams, followed by challenges relating to planning and coordination, specifically the challenges of being flexible and adaptive when constrained by operating procedures. In addition, the current focus on maximizing short-term employment was perceived by some as limiting the efficiency and long-term effectiveness of the WfW program in achieving its environmental and social goals. We suggest that improving the conditions and duration of employment could improve the effectiveness of invasive alien plant control and ecological outcomes. We also suggest that WfW measure the impacts of their interventions through an adaptive management approach so that it can learn and adapt to the challenges it faces.
- Full Text:
- Date Issued: 2013
Photophysical and photochemical properties of a novel thiol terminated low symmetry zinc phthalocyanine complex and its gold nanoparticles conjugate
- Mthethwa, Thandekile P, Durmus, Mahmut, Nyokong, Tebello
- Authors: Mthethwa, Thandekile P , Durmus, Mahmut , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231474 , vital:49891 , xlink:href="https://doi.org/10.1039/C3DT32698E"
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone.
- Full Text:
- Date Issued: 2013
- Authors: Mthethwa, Thandekile P , Durmus, Mahmut , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231474 , vital:49891 , xlink:href="https://doi.org/10.1039/C3DT32698E"
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone.
- Full Text:
- Date Issued: 2013
The Dangers of Student-Centered Learning-A Caution about Blind Spots in the Scholarship of Teaching and Learning
- Authors: McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187362 , vital:44624 , xlink:href="https://doi.org/10.20429/ijsotl.2013.070206"
- Description: Student-centered learning is an increasingly popular approach that shifts the focus from the teacher to the student. The approach argues that we need to have a clear understanding of who our students are and what their needs are in order for us to provide quality education. This paper applauds the focus on the student but raises two concerns about absences in this approach. Firstly, student-centered approaches rarely consider the actual knowledge being taught and learnt. There is little consideration of how the disciplinary knowledge is constructed and what norms and values underpin such constructions. Secondly, student-centered approaches are often undertaken within the dominant autonomous discourse where student success or failure is seen to result from characteristics inherent in the student. She is understood as an individual rather than as a member of a larger social group and there is equally little acknowledgement of the socially constructed nature of universities and the practices within them.
- Full Text:
- Date Issued: 2013
- Authors: McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187362 , vital:44624 , xlink:href="https://doi.org/10.20429/ijsotl.2013.070206"
- Description: Student-centered learning is an increasingly popular approach that shifts the focus from the teacher to the student. The approach argues that we need to have a clear understanding of who our students are and what their needs are in order for us to provide quality education. This paper applauds the focus on the student but raises two concerns about absences in this approach. Firstly, student-centered approaches rarely consider the actual knowledge being taught and learnt. There is little consideration of how the disciplinary knowledge is constructed and what norms and values underpin such constructions. Secondly, student-centered approaches are often undertaken within the dominant autonomous discourse where student success or failure is seen to result from characteristics inherent in the student. She is understood as an individual rather than as a member of a larger social group and there is equally little acknowledgement of the socially constructed nature of universities and the practices within them.
- Full Text:
- Date Issued: 2013
Gazing at Exhibit A
- Authors: Krueger, Anton
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229643 , vital:49696 , xlink:href="http://liminalities.net/9-1/exhibit.pdf"
- Description: Brett Bailey recently toured a new work in Europe and South Africa, called The Exhibit Series (2010-2013). In different countries the work has appeared under different titles—Exhibit A and Exhibit B, while Exhibit C will be produced in 2014. These productions replicate and parody ethnographic spectacles of the nineteenth century, interrogating European colonial atrocities in Africa, as well as contemporary xenophobia. They consist of a series of installations housed in individual rooms that audience members enter one by one. Inside these rooms one is confronted by beautifully arranged spectacles referencing historical atrocities committed in Namibia by German speaking peoples, as well as atrocities under the Belgian and French colonial regimes in the two Congos. The “exhibits” also include references to more recent incidents of European racism against migrants from Africa. The work has been both applauded and derided. In Berlin, for example, activists called it “a human zoo” and protested that this was “the wrong way to discuss a violent colonial history,”1 while others have called the work “haunting”, praising the production for its “dignity” and “beauty.”2
- Full Text:
- Date Issued: 2013
- Authors: Krueger, Anton
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229643 , vital:49696 , xlink:href="http://liminalities.net/9-1/exhibit.pdf"
- Description: Brett Bailey recently toured a new work in Europe and South Africa, called The Exhibit Series (2010-2013). In different countries the work has appeared under different titles—Exhibit A and Exhibit B, while Exhibit C will be produced in 2014. These productions replicate and parody ethnographic spectacles of the nineteenth century, interrogating European colonial atrocities in Africa, as well as contemporary xenophobia. They consist of a series of installations housed in individual rooms that audience members enter one by one. Inside these rooms one is confronted by beautifully arranged spectacles referencing historical atrocities committed in Namibia by German speaking peoples, as well as atrocities under the Belgian and French colonial regimes in the two Congos. The “exhibits” also include references to more recent incidents of European racism against migrants from Africa. The work has been both applauded and derided. In Berlin, for example, activists called it “a human zoo” and protested that this was “the wrong way to discuss a violent colonial history,”1 while others have called the work “haunting”, praising the production for its “dignity” and “beauty.”2
- Full Text:
- Date Issued: 2013
Forced degradation studies of clobetasol 17‐propionate in methanol, propylene glycol, as bulk drug and cream formulations by RP‐HPLC
- Fauzee, Ayesha F, Walker, Roderick B
- Authors: Fauzee, Ayesha F , Walker, Roderick B
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184005 , vital:44154 , xlink:href="https://doi.org/10.1002/jssc.201200969"
- Description: A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 μm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min−1. Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15–15 μg mL−1. All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations.
- Full Text:
- Date Issued: 2013
- Authors: Fauzee, Ayesha F , Walker, Roderick B
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184005 , vital:44154 , xlink:href="https://doi.org/10.1002/jssc.201200969"
- Description: A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 μm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min−1. Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15–15 μg mL−1. All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations.
- Full Text:
- Date Issued: 2013
MCD spectroscopy and TD-DFT calculations of a naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer
- Mack, John, Liang, Xu, Dubinina, Tatiana V, Tomilova, Larisa G, Nyokong, Tebello, Kobayashi, Nagao
- Authors: Mack, John , Liang, Xu , Dubinina, Tatiana V , Tomilova, Larisa G , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232511 , vital:49998 , xlink:href="https://doi.org/10.1142/S1088424613500259"
- Description: Magnetic circular dichroism (MCD) spectroscopy and TD-DFT calculations are used to analyze the electronic structure and optical properties of an alkyl-substituted naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer. An analysis of the MCD spectrum of the naphthalene-ring-bridged dimer relative to those of benzene-bridged compounds reported previously, demonstrates that there is a significantly weaker interaction between the two phthalocyanine rings. TD-DFT results obtained using the B3LYP functional with 6–31G basis sets were found to be problematic. Closer agreement with the experimental data is obtained when the CAM-B3LYP functional is used instead. The naphthalene-ring-bridged compound is found to be unsuitable for use as a photosensitizer for the formation of singlet oxygen, because the ΦT values are negligible.
- Full Text:
- Date Issued: 2013
- Authors: Mack, John , Liang, Xu , Dubinina, Tatiana V , Tomilova, Larisa G , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232511 , vital:49998 , xlink:href="https://doi.org/10.1142/S1088424613500259"
- Description: Magnetic circular dichroism (MCD) spectroscopy and TD-DFT calculations are used to analyze the electronic structure and optical properties of an alkyl-substituted naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer. An analysis of the MCD spectrum of the naphthalene-ring-bridged dimer relative to those of benzene-bridged compounds reported previously, demonstrates that there is a significantly weaker interaction between the two phthalocyanine rings. TD-DFT results obtained using the B3LYP functional with 6–31G basis sets were found to be problematic. Closer agreement with the experimental data is obtained when the CAM-B3LYP functional is used instead. The naphthalene-ring-bridged compound is found to be unsuitable for use as a photosensitizer for the formation of singlet oxygen, because the ΦT values are negligible.
- Full Text:
- Date Issued: 2013
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
Editorial. Methodology, Context and Quality
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013