Investigation of local institutions for the application of the in-field rain water harvesting technology in rural areas: the case of Guquka and Khayaletu in Nkonkobe Municipality in central Eastern Cape
- Authors: Mfaca, Malibongwe
- Date: 2011
- Subjects: Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11184 , http://hdl.handle.net/10353/d1001031 , Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
- Full Text: false
- Authors: Mfaca, Malibongwe
- Date: 2011
- Subjects: Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11184 , http://hdl.handle.net/10353/d1001031 , Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
- Full Text: false
Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa: a case study of the Balfour Formation in the Eastern Cape Province
- Authors: Yu, Liuji
- Date: 2011
- Subjects: Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11522 , http://hdl.handle.net/10353/415 , Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Description: Hydrogeologists have faced serious challenges worldwide in the characterization of fractured rock aquifers due to the heterogeneous nature of the imbedded geology. The bulk flow parameters in the Karoo strata in South Africa are specifically uncertain since most models are based on homogenous block systems. As part of a WRC research project, entitled “Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa”, this study focuses on the characterization, borehole drilling, flow parameter measurements and groundwater quality assessment of the Balfour Formation in the Beaufort Group of the Karoo Supergroup in the Eastern Cape, South Africa, which is seriously heterogeneous in deposition and has also been largely neglected as drilling targets for groundwater. The Balfour Formation comprises mostly mudstone, shale and sandstone, formed in a braided and meandering river system. In addition to the heterogeneous deposition, the flow pathways in this aquifer system are not fully understood due to lack of actual measurement data. The methods used in this study include field mapping, site characterization, borehole drilling, and pumping and tracer testing in order to obtain the borehole yield, aquifer transmissivity, storativity and groundwater flow velocity. In addition, the groundwater chemistry was also studied to determine quality for use and possible connectivity with the nearby Tyume River and to determine potential sources of groundwater contamination. The results obtained include: 1) The study area is predominantly mudstone/shale with thin layers and lenses of siltstone and sandstone, which are interbedded; 2) Two boreholes were successfully drilled, which had yields in excess of 10 l/s in four water levels (at 7, 22, 54 and 65 m); 3) The estimated average transmissivity is 246 m 2/day according to the recovery test; 4) The estimated seepage velocity is 120 m/day according to tracer tests in the aquifer between the two boreholes which are 5 m apart; and 5) The water chemical type is the combination of HCO3-, Cl-and SO42- , which is distinguishable from that of the Tyume river; 6) There is no evidence for groundwater recharge to the deep aquifers from the Tyume river, based on the differences of the water chemistry; 7) The elements Ca, Cl, Na and C are distributed more than 90% as free ion species in BH2 borehole water; and 8) The groundwater in BH2 borehole is undersaturated (negative SI) with respect to some minerals (for example: anhydrite, fluorite, gypsum and halite), oversaturated (positive SI) with respect to some minerals (for example: aragonite, calcite and dolomite). It is concluded that there is a great potential to obtain drilling targets for high yielding boreholes in the sedimentary rocks of the Balfour Formation in the Karoo Supergroup.
- Full Text:
- Authors: Yu, Liuji
- Date: 2011
- Subjects: Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11522 , http://hdl.handle.net/10353/415 , Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Description: Hydrogeologists have faced serious challenges worldwide in the characterization of fractured rock aquifers due to the heterogeneous nature of the imbedded geology. The bulk flow parameters in the Karoo strata in South Africa are specifically uncertain since most models are based on homogenous block systems. As part of a WRC research project, entitled “Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa”, this study focuses on the characterization, borehole drilling, flow parameter measurements and groundwater quality assessment of the Balfour Formation in the Beaufort Group of the Karoo Supergroup in the Eastern Cape, South Africa, which is seriously heterogeneous in deposition and has also been largely neglected as drilling targets for groundwater. The Balfour Formation comprises mostly mudstone, shale and sandstone, formed in a braided and meandering river system. In addition to the heterogeneous deposition, the flow pathways in this aquifer system are not fully understood due to lack of actual measurement data. The methods used in this study include field mapping, site characterization, borehole drilling, and pumping and tracer testing in order to obtain the borehole yield, aquifer transmissivity, storativity and groundwater flow velocity. In addition, the groundwater chemistry was also studied to determine quality for use and possible connectivity with the nearby Tyume River and to determine potential sources of groundwater contamination. The results obtained include: 1) The study area is predominantly mudstone/shale with thin layers and lenses of siltstone and sandstone, which are interbedded; 2) Two boreholes were successfully drilled, which had yields in excess of 10 l/s in four water levels (at 7, 22, 54 and 65 m); 3) The estimated average transmissivity is 246 m 2/day according to the recovery test; 4) The estimated seepage velocity is 120 m/day according to tracer tests in the aquifer between the two boreholes which are 5 m apart; and 5) The water chemical type is the combination of HCO3-, Cl-and SO42- , which is distinguishable from that of the Tyume river; 6) There is no evidence for groundwater recharge to the deep aquifers from the Tyume river, based on the differences of the water chemistry; 7) The elements Ca, Cl, Na and C are distributed more than 90% as free ion species in BH2 borehole water; and 8) The groundwater in BH2 borehole is undersaturated (negative SI) with respect to some minerals (for example: anhydrite, fluorite, gypsum and halite), oversaturated (positive SI) with respect to some minerals (for example: aragonite, calcite and dolomite). It is concluded that there is a great potential to obtain drilling targets for high yielding boreholes in the sedimentary rocks of the Balfour Formation in the Karoo Supergroup.
- Full Text:
Phytochemical analysis and bioactivity of selected South African medicinal plants on clinical isolates of Helicobacter pylori
- Authors: Njume, Collise
- Date: 2011
- Subjects: Helicobacter pylori , Medicinal plants -- Biotechnology , Traditional medicine -- South Africa -- Eastern Cape , Antibiotics , Drug resistance in microorganisms , Extracts , Helicobacter pylori infections
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11260 , http://hdl.handle.net/10353/449 , Helicobacter pylori , Medicinal plants -- Biotechnology , Traditional medicine -- South Africa -- Eastern Cape , Antibiotics , Drug resistance in microorganisms , Extracts , Helicobacter pylori infections
- Description: Medicinal plants have been used as traditional medicine in the treatment of numerous human diseases for thousands of years in many parts of the world. In the developing world, especially in rural areas, herbal remedies continue to be a primary source of medicine. Scientifically, medicinal plants have proven to be an abundant source of biologically active compounds, many of which have already been formulated into useful therapeutic substances or have provided a basis for the development of new lead molecules for pharmaceuticals. Antibiotic resistance, undesireable side effects and expences associated with the use of combination therapy in the treatment of Helicobacter pylori infections have generated a considerable interest in the study of medicinal plants as potential sources of new drugs against this organism. The high complexicity of bioactive compounds accumulated in plants coupled with their broad antimicrobial activity may make it difficult for pathogenic organisms, including H. pylori to acquire resistance during treatment. This study therefore evaluates the antimicrobial potential of selected South African medicinal plants employed in the treatment of H. pylori-related infections, and the subsequent isolation of the plant active principles. An ethnobotanical survey of plants used in the treatment of H. pylori-related infections was conducted in the study area. Crude extracts of Combretum molle, Sclerocarya birrea, Garcinia kola, Alepidea amatymbica and 2 Strychnos species were screened against 30 clinical strains of H. pylori and 2 standard control strains (NCTC 11638 and ATCC 43526). In the preliminary stages of this study, ethyl acetate, acetone, ethanol, methanol and water extracts of the plants were tested against H. pylori by agar well diffusion and micro broth dilution methods. The plant crude extracts that exhibited anti-H. pylori activity with a iv percentage susceptibility of 50 percent and above were considered for the rate of kill assays and the most active crude extracts selected for bio-assay guided isolation of the active ingredient. Preliminary fractionation of the crude extract was achieved by thin layer chromatography (TLC) using different solvent combinations; hexane/diethylether (HDE), ethyl acetate/methanol/water (EMW) and chloroform/ethyl acetate/formic acid (CEF) in order to determine the most suitable combination for column chromatography (CC) and subsequent testing by indirect bioautography. The extract was then fractionated in a silica gel column using previously determined solvent combinations as eluent. Active fractions obtained from column chromatography separations were further fractionated and the compounds identified by gas chromatography/mass spectrometry (GC/MS) analysis. All the plants exhibited antimicrobial activity against H. pylori with zone of inhibition diameters ranging from 0 - 38 mm and minimum inhibitory concentration (MIC) values ranging from 0.06 - 5.0 mg/mL. The most active plant extracts were the acetone extract of C. molle with a percentage susceptibility of 87.1 percent, acetone and aqueous extracts of S. birrea (71 percent each) and the ethanolic extracts of G. kola (53.3 percent). Except for the aqueous extract, these extracts also exhibited a strong bactericidal activity against H. pylori at different concentrations. TLC analysis revealed the presence of 9 components in the acetone extract of S. birrea with the EMW solvent system as opposed to 5 and 8 with HDE and CEF respectively. Bioassay-guided isolation led to the identification of 52 compounds from the acetone extract of S. birrea with n-octacosane being the most abundant (41.68 percent). This was followed by pyrrolidine (38.91 percent), terpinen-4-ol (38.3 percent), n-eicosane (24.98 percent), cyclopentane (16.76 percent), n-triacontane (16.28 percent), aromadendrene (13.63 percent) and α-gujunene (8.77 percent). Terpinen-4-ol and pyrrolidine demonstrated strong antimicrobial activity against H. pylori at all concentrations tested. These results may serve as preliminary scientific validation of the ethnomedicinal uses of the above mentioned plants in the treatment of H. pylori-related infections in South Africa. Terpinen-4-ol and pyrrolidine could be considered for further evaluation as therapeutic or prophylactic agents in the treatment of H. pylori-related infections. However, further investigations would be necessary to determine their toxicological properties, in-vivo potencies and mechanism of action against H.pylori
- Full Text:
- Authors: Njume, Collise
- Date: 2011
- Subjects: Helicobacter pylori , Medicinal plants -- Biotechnology , Traditional medicine -- South Africa -- Eastern Cape , Antibiotics , Drug resistance in microorganisms , Extracts , Helicobacter pylori infections
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11260 , http://hdl.handle.net/10353/449 , Helicobacter pylori , Medicinal plants -- Biotechnology , Traditional medicine -- South Africa -- Eastern Cape , Antibiotics , Drug resistance in microorganisms , Extracts , Helicobacter pylori infections
- Description: Medicinal plants have been used as traditional medicine in the treatment of numerous human diseases for thousands of years in many parts of the world. In the developing world, especially in rural areas, herbal remedies continue to be a primary source of medicine. Scientifically, medicinal plants have proven to be an abundant source of biologically active compounds, many of which have already been formulated into useful therapeutic substances or have provided a basis for the development of new lead molecules for pharmaceuticals. Antibiotic resistance, undesireable side effects and expences associated with the use of combination therapy in the treatment of Helicobacter pylori infections have generated a considerable interest in the study of medicinal plants as potential sources of new drugs against this organism. The high complexicity of bioactive compounds accumulated in plants coupled with their broad antimicrobial activity may make it difficult for pathogenic organisms, including H. pylori to acquire resistance during treatment. This study therefore evaluates the antimicrobial potential of selected South African medicinal plants employed in the treatment of H. pylori-related infections, and the subsequent isolation of the plant active principles. An ethnobotanical survey of plants used in the treatment of H. pylori-related infections was conducted in the study area. Crude extracts of Combretum molle, Sclerocarya birrea, Garcinia kola, Alepidea amatymbica and 2 Strychnos species were screened against 30 clinical strains of H. pylori and 2 standard control strains (NCTC 11638 and ATCC 43526). In the preliminary stages of this study, ethyl acetate, acetone, ethanol, methanol and water extracts of the plants were tested against H. pylori by agar well diffusion and micro broth dilution methods. The plant crude extracts that exhibited anti-H. pylori activity with a iv percentage susceptibility of 50 percent and above were considered for the rate of kill assays and the most active crude extracts selected for bio-assay guided isolation of the active ingredient. Preliminary fractionation of the crude extract was achieved by thin layer chromatography (TLC) using different solvent combinations; hexane/diethylether (HDE), ethyl acetate/methanol/water (EMW) and chloroform/ethyl acetate/formic acid (CEF) in order to determine the most suitable combination for column chromatography (CC) and subsequent testing by indirect bioautography. The extract was then fractionated in a silica gel column using previously determined solvent combinations as eluent. Active fractions obtained from column chromatography separations were further fractionated and the compounds identified by gas chromatography/mass spectrometry (GC/MS) analysis. All the plants exhibited antimicrobial activity against H. pylori with zone of inhibition diameters ranging from 0 - 38 mm and minimum inhibitory concentration (MIC) values ranging from 0.06 - 5.0 mg/mL. The most active plant extracts were the acetone extract of C. molle with a percentage susceptibility of 87.1 percent, acetone and aqueous extracts of S. birrea (71 percent each) and the ethanolic extracts of G. kola (53.3 percent). Except for the aqueous extract, these extracts also exhibited a strong bactericidal activity against H. pylori at different concentrations. TLC analysis revealed the presence of 9 components in the acetone extract of S. birrea with the EMW solvent system as opposed to 5 and 8 with HDE and CEF respectively. Bioassay-guided isolation led to the identification of 52 compounds from the acetone extract of S. birrea with n-octacosane being the most abundant (41.68 percent). This was followed by pyrrolidine (38.91 percent), terpinen-4-ol (38.3 percent), n-eicosane (24.98 percent), cyclopentane (16.76 percent), n-triacontane (16.28 percent), aromadendrene (13.63 percent) and α-gujunene (8.77 percent). Terpinen-4-ol and pyrrolidine demonstrated strong antimicrobial activity against H. pylori at all concentrations tested. These results may serve as preliminary scientific validation of the ethnomedicinal uses of the above mentioned plants in the treatment of H. pylori-related infections in South Africa. Terpinen-4-ol and pyrrolidine could be considered for further evaluation as therapeutic or prophylactic agents in the treatment of H. pylori-related infections. However, further investigations would be necessary to determine their toxicological properties, in-vivo potencies and mechanism of action against H.pylori
- Full Text:
Phytochemical analysis and bioactivity of the stem bark of Combretum Molle on some selected bacterial pathogens
- Authors: Nyenje, Mirriam, E
- Date: 2011
- Subjects: Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11261 , http://hdl.handle.net/10353/391 , Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Description: Antimicrobial resistance is a worldwide problem that has deleterious long-term effects as the development of drug resistance outpaces the development of new drugs. Plants have been used for many generations for healing purposes, and screening of extracts of these plants has often yielded positive outcomes. This study was aimed at isolating and characterizing the major active antimicrobial compounds present in the stem bark of C. molle, in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. Various solvents (hexane, ethyl acetate, dichloromethane, acetone, ethanol and methanol) were used for extraction. The agar well diffusion technique was used to screen for antimicrobial activity of C. molle extracts against Streptococcus pyogenes ATCC 49399, Plesiomonas shigelloides ATCC 51903, Pseudomonas aeruginosa ATCC 15442, Helicobacter pylori ATCC 43526 and Helicobacter pylori 252C (clinical isolate); minimum inhibition concentration (MIC) of the most active extracts was determined by the broth dilution method. Fractionation of acetone extract was done by thin layer chromatography (TLC) and bioautography to determine the compounds present and their antimicrobial activity respectively. The acetone extract was purified by column chromatography and their MIC determined. The most potent fraction (EA4) was subjected to Gas chromatography- Mass spectrometry (GC-MS) and High performance liquid chromatography (HPLC) for identification of the active compounds. Results were analyzed by the Fisher‟s exact test. All the extracts tested demonstrated antimicrobial activity with zone diameters of inhibition ranging from 0–32 mm. Acetone was the most potent extract with its MIC ranging from 0.078–5.0 mg/mL. Seventeen fractions were collected from column chromatography and the most active fraction against all the organisms was EA 4 (eluted with 100 percent ethyl acetate), with its MIC ranging from 0.078 - 2.5mg/mL. There was no statistically significant difference (P>0.05) in the potency of the xii four extracts (acetone, methanol, ethanol and ethyl acetate) and antibiotic (ciprofloxacin) on the different bacterial strains tested, likewise the crude extract and the fractions. No compound was detected by GC-MS whereas numerous peaks were identified by HPLC implying that the active compounds in this plant are non volatile. We could not identify the compounds thereby proposing further studies using Nuclear magnetic resonance to identify the compounds. The study revealed that the acetone extract of C. molle was the most active against all the test organisms and therefore justifies the use of this plant in traditional medicine.
- Full Text:
- Authors: Nyenje, Mirriam, E
- Date: 2011
- Subjects: Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11261 , http://hdl.handle.net/10353/391 , Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Description: Antimicrobial resistance is a worldwide problem that has deleterious long-term effects as the development of drug resistance outpaces the development of new drugs. Plants have been used for many generations for healing purposes, and screening of extracts of these plants has often yielded positive outcomes. This study was aimed at isolating and characterizing the major active antimicrobial compounds present in the stem bark of C. molle, in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. Various solvents (hexane, ethyl acetate, dichloromethane, acetone, ethanol and methanol) were used for extraction. The agar well diffusion technique was used to screen for antimicrobial activity of C. molle extracts against Streptococcus pyogenes ATCC 49399, Plesiomonas shigelloides ATCC 51903, Pseudomonas aeruginosa ATCC 15442, Helicobacter pylori ATCC 43526 and Helicobacter pylori 252C (clinical isolate); minimum inhibition concentration (MIC) of the most active extracts was determined by the broth dilution method. Fractionation of acetone extract was done by thin layer chromatography (TLC) and bioautography to determine the compounds present and their antimicrobial activity respectively. The acetone extract was purified by column chromatography and their MIC determined. The most potent fraction (EA4) was subjected to Gas chromatography- Mass spectrometry (GC-MS) and High performance liquid chromatography (HPLC) for identification of the active compounds. Results were analyzed by the Fisher‟s exact test. All the extracts tested demonstrated antimicrobial activity with zone diameters of inhibition ranging from 0–32 mm. Acetone was the most potent extract with its MIC ranging from 0.078–5.0 mg/mL. Seventeen fractions were collected from column chromatography and the most active fraction against all the organisms was EA 4 (eluted with 100 percent ethyl acetate), with its MIC ranging from 0.078 - 2.5mg/mL. There was no statistically significant difference (P>0.05) in the potency of the xii four extracts (acetone, methanol, ethanol and ethyl acetate) and antibiotic (ciprofloxacin) on the different bacterial strains tested, likewise the crude extract and the fractions. No compound was detected by GC-MS whereas numerous peaks were identified by HPLC implying that the active compounds in this plant are non volatile. We could not identify the compounds thereby proposing further studies using Nuclear magnetic resonance to identify the compounds. The study revealed that the acetone extract of C. molle was the most active against all the test organisms and therefore justifies the use of this plant in traditional medicine.
- Full Text:
Preliminary investigation into estimating eye disease incidence rate from age specific prevalence data
- Authors: Majeke, Lunga
- Date: 2011
- Subjects: Medicine -- Research -- Statistical methods , Eye -- Diseases -- Statistics , Incidence functions , Regression analysis -- Data processing , Regression analysis -- Mathematical models -- Evaluation , Medical statistics
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11776 , http://hdl.handle.net/10353/464 , Medicine -- Research -- Statistical methods , Eye -- Diseases -- Statistics , Incidence functions , Regression analysis -- Data processing , Regression analysis -- Mathematical models -- Evaluation , Medical statistics
- Description: This study presents the methodology for estimating the incidence rate from the age specific prevalence data of three different eye diseases. We consider both situations where the mortality may differ from one person to another, with and without the disease. The method used was developed by Marvin J. Podgor for estimating incidence rate from prevalence data. It delves into the application of logistic regression to obtain the smoothed prevalence rates that helps in obtaining incidence rate. The study concluded that the use of logistic regression can produce a meaningful model, and the incidence rates of these diseases were not affected by the assumption of differential mortality.
- Full Text:
- Authors: Majeke, Lunga
- Date: 2011
- Subjects: Medicine -- Research -- Statistical methods , Eye -- Diseases -- Statistics , Incidence functions , Regression analysis -- Data processing , Regression analysis -- Mathematical models -- Evaluation , Medical statistics
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11776 , http://hdl.handle.net/10353/464 , Medicine -- Research -- Statistical methods , Eye -- Diseases -- Statistics , Incidence functions , Regression analysis -- Data processing , Regression analysis -- Mathematical models -- Evaluation , Medical statistics
- Description: This study presents the methodology for estimating the incidence rate from the age specific prevalence data of three different eye diseases. We consider both situations where the mortality may differ from one person to another, with and without the disease. The method used was developed by Marvin J. Podgor for estimating incidence rate from prevalence data. It delves into the application of logistic regression to obtain the smoothed prevalence rates that helps in obtaining incidence rate. The study concluded that the use of logistic regression can produce a meaningful model, and the incidence rates of these diseases were not affected by the assumption of differential mortality.
- Full Text:
Preparation and evaluation of Lignocellulose-Montmorillonite nanocomposites for the adsorption of some heavy metals and organic dyes from aqueous solution
- Authors: Bunhu, Tavengwa
- Date: 2011
- Subjects: Lignocellulose , Lignocellulose -- Biodegradation , Water -- Purification , Adsorption , Separation (Technology) , Dyes and dyeing , Montmorillonite
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11333 , http://hdl.handle.net/10353/535 , Lignocellulose , Lignocellulose -- Biodegradation , Water -- Purification , Adsorption , Separation (Technology) , Dyes and dyeing , Montmorillonite
- Description: The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.
- Full Text:
- Authors: Bunhu, Tavengwa
- Date: 2011
- Subjects: Lignocellulose , Lignocellulose -- Biodegradation , Water -- Purification , Adsorption , Separation (Technology) , Dyes and dyeing , Montmorillonite
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11333 , http://hdl.handle.net/10353/535 , Lignocellulose , Lignocellulose -- Biodegradation , Water -- Purification , Adsorption , Separation (Technology) , Dyes and dyeing , Montmorillonite
- Description: The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.
- Full Text:
Preparation of photocatalytic TiO₂ nanoparticles immobilized on carbon nanofibres for water purification
- Authors: Nyamukamba, Pardon
- Date: 2011
- Subjects: Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11330 , http://hdl.handle.net/10353/367 , Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Description: Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
- Full Text:
- Authors: Nyamukamba, Pardon
- Date: 2011
- Subjects: Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11330 , http://hdl.handle.net/10353/367 , Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Description: Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
- Full Text:
Rainfall intensity, kinetic energy and erosivity of individual rainfall events on the island of Mauritius
- Authors: Mongwa, Themba
- Date: 2011
- Subjects: Rain and rainfall -- Mauritius , Soil erosion -- Mauritius , Rainfall intensity duration frequencies -- Mauritius
- Language: English
- Type: Thesis , Masters , MSc (Geography)
- Identifier: vital:11506 , http://hdl.handle.net/10353/452 , Rain and rainfall -- Mauritius , Soil erosion -- Mauritius , Rainfall intensity duration frequencies -- Mauritius
- Description: On most tropical volcanic islands the risk for soil erosion is enhanced due to a complex topography, high intensity rainfall and the exploitation of land for agriculture. Mauritius is a typical maritime tropical volcanic island with a distinct elevated interior. Rainfall is dominated by tropical weather systems and trade winds and the island is under intensive cultivation. Rainfall depth, duration, intensity, kinetic energy and erosivity were analysed for 385 erosive rainfall events at five locations over a five year period (2004 to 2008) on the island of Mauritius. Two stations located on the west coast and three stations sited on the Central Plateau above 550 m a.s.l. are used to provide detailed rainfall data at six minute intervals. Erosive storm events, defined here as a total rainfall exceeding 12.5 mm and a maximum 6-minute intensity exceeding 25 mm/hour, are found to differ markedly between the coastal lowlands and the elevated interior with regards to the frequency, the total rainfall generated, the duration, total kinetic energy and total erosivity of individual events. However, mean kinetic energy, mean and maximum rainfall erosivity (EI30) and maximum intensities (I30) from individual erosive events do not show this distinct differentiation. Erosivity measured during summer exceeds that recorded in winter, but the data indicate that large percentages of winter rainfall on Mauritius are defined as erosive and non-tropical cyclone rainfall can pose a substantial erosion risk. In this maritime tropical environment with its elevated interior, soil erosion risk occurs from storm scale to synoptic scale rainfall events and extreme events generate the bulk of the erosivity. Findings show that using rainfall records at an event scale within soil erosion risk assessments on tropical islands with a complex topography will increase the effectiveness of erosivity estimates
- Full Text:
- Authors: Mongwa, Themba
- Date: 2011
- Subjects: Rain and rainfall -- Mauritius , Soil erosion -- Mauritius , Rainfall intensity duration frequencies -- Mauritius
- Language: English
- Type: Thesis , Masters , MSc (Geography)
- Identifier: vital:11506 , http://hdl.handle.net/10353/452 , Rain and rainfall -- Mauritius , Soil erosion -- Mauritius , Rainfall intensity duration frequencies -- Mauritius
- Description: On most tropical volcanic islands the risk for soil erosion is enhanced due to a complex topography, high intensity rainfall and the exploitation of land for agriculture. Mauritius is a typical maritime tropical volcanic island with a distinct elevated interior. Rainfall is dominated by tropical weather systems and trade winds and the island is under intensive cultivation. Rainfall depth, duration, intensity, kinetic energy and erosivity were analysed for 385 erosive rainfall events at five locations over a five year period (2004 to 2008) on the island of Mauritius. Two stations located on the west coast and three stations sited on the Central Plateau above 550 m a.s.l. are used to provide detailed rainfall data at six minute intervals. Erosive storm events, defined here as a total rainfall exceeding 12.5 mm and a maximum 6-minute intensity exceeding 25 mm/hour, are found to differ markedly between the coastal lowlands and the elevated interior with regards to the frequency, the total rainfall generated, the duration, total kinetic energy and total erosivity of individual events. However, mean kinetic energy, mean and maximum rainfall erosivity (EI30) and maximum intensities (I30) from individual erosive events do not show this distinct differentiation. Erosivity measured during summer exceeds that recorded in winter, but the data indicate that large percentages of winter rainfall on Mauritius are defined as erosive and non-tropical cyclone rainfall can pose a substantial erosion risk. In this maritime tropical environment with its elevated interior, soil erosion risk occurs from storm scale to synoptic scale rainfall events and extreme events generate the bulk of the erosivity. Findings show that using rainfall records at an event scale within soil erosion risk assessments on tropical islands with a complex topography will increase the effectiveness of erosivity estimates
- Full Text:
Randomization in a two armed clinical trial: an overview of different randomization techniques
- Authors: Batidzirai, Jesca Mercy
- Date: 2011
- Subjects: Clinical trials -- Statistical methods , Biometry , Sampling (Statistics)
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11781 , http://hdl.handle.net/10353/395 , Clinical trials -- Statistical methods , Biometry , Sampling (Statistics)
- Description: Randomization is the key element of any sensible clinical trial. It is the only way we can be sure that the patients have been allocated into the treatment groups without bias and that the treatment groups are almost similar before the start of the trial. The randomization schemes used to allocate patients into the treatment groups play a role in achieving this goal. This study uses SAS simulations to do categorical data analysis and comparison of differences between two main randomization schemes namely unrestricted and restricted randomization in dental studies where there are small samples, i.e. simple randomization and the minimization method respectively. Results show that minimization produces almost equally sized treatment groups, but simple randomization is weak in balancing prognostic factors. Nevertheless, simple randomization can also produce balanced groups even in small samples, by chance. Statistical power is also improved when minimization is used than in simple randomization, but bigger samples might be needed to boost the power.
- Full Text:
- Authors: Batidzirai, Jesca Mercy
- Date: 2011
- Subjects: Clinical trials -- Statistical methods , Biometry , Sampling (Statistics)
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11781 , http://hdl.handle.net/10353/395 , Clinical trials -- Statistical methods , Biometry , Sampling (Statistics)
- Description: Randomization is the key element of any sensible clinical trial. It is the only way we can be sure that the patients have been allocated into the treatment groups without bias and that the treatment groups are almost similar before the start of the trial. The randomization schemes used to allocate patients into the treatment groups play a role in achieving this goal. This study uses SAS simulations to do categorical data analysis and comparison of differences between two main randomization schemes namely unrestricted and restricted randomization in dental studies where there are small samples, i.e. simple randomization and the minimization method respectively. Results show that minimization produces almost equally sized treatment groups, but simple randomization is weak in balancing prognostic factors. Nevertheless, simple randomization can also produce balanced groups even in small samples, by chance. Statistical power is also improved when minimization is used than in simple randomization, but bigger samples might be needed to boost the power.
- Full Text:
The economics of Bt maize/yieldgard production: case of smallholder farmers in the Eastern Cape Province
- Mandikiana, Brian Washington
- Authors: Mandikiana, Brian Washington
- Date: 2011
- Subjects: Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11167 , http://hdl.handle.net/10353/326 , Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Description: Maize is the staple food for most South Africans. This implies that any damage to the maize crop will affect food security of many South Africans. Although Eastern Cape Province is not a traditionally maize producing area, smallholder farmers in the province produce it mostly for subsistence purposes and some sell the surplus on the local market or use it to secure other good through barter trading. In South Africa, insect-resistant Bt maize/yieldgard has been used commercially for approximately 10 years now. Available impact studies on Bt maize reveal that, this technology is beneficial not only to farmers but consumers of maize products as well. Welfare gains as well as positive effects for human health are realised by both groups. Due to the costs and effectiveness associated with traditional and conventional maize stem borer control methods, Bt technology has the potential to be part of the solution. This thesis has attempted to investigate the economic viability of planting Bt maize seeds under smallholder farming conditions and identify factors as well as perceptions relating to attributes of Bt maize and to analyze the relationships between those perceptions and choices regarding use of Bt technology. Data was collected from 90 households who were selected using purposive sampling through the use of the snowball method. To collect data, a questionnaire was administered through face-to-face interviews. Gross margin analysis revealed that Bt maize is a more profitable option as compared to conventional maize seeds. Furthermore, econometric analyses, through use of the binomial regression model revealed that perceptions could be used to distinguish between users and non-users of Bt maize seed in the Eastern Cape Province. Results of inferential analysis indicate that the statistically significant variables at 5% level are gene erosion, quality and nutrition of products and food labels for Bt maize products perceptions. On the other hand, low expenses, seed market availability and farmers’ knowledge perceptions were significant at 10%. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of Bt maize adoption. In view of the research findings, several policy proposals are suggested to support policy formulation. Key words: Bacillus thuringiensis (Bt) maize, yieldgard, smallholder farmers, perceptions, Flagstaff, gross margin analysis, binomial logistic regression model, Eastern Cape Province.
- Full Text:
- Authors: Mandikiana, Brian Washington
- Date: 2011
- Subjects: Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11167 , http://hdl.handle.net/10353/326 , Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Description: Maize is the staple food for most South Africans. This implies that any damage to the maize crop will affect food security of many South Africans. Although Eastern Cape Province is not a traditionally maize producing area, smallholder farmers in the province produce it mostly for subsistence purposes and some sell the surplus on the local market or use it to secure other good through barter trading. In South Africa, insect-resistant Bt maize/yieldgard has been used commercially for approximately 10 years now. Available impact studies on Bt maize reveal that, this technology is beneficial not only to farmers but consumers of maize products as well. Welfare gains as well as positive effects for human health are realised by both groups. Due to the costs and effectiveness associated with traditional and conventional maize stem borer control methods, Bt technology has the potential to be part of the solution. This thesis has attempted to investigate the economic viability of planting Bt maize seeds under smallholder farming conditions and identify factors as well as perceptions relating to attributes of Bt maize and to analyze the relationships between those perceptions and choices regarding use of Bt technology. Data was collected from 90 households who were selected using purposive sampling through the use of the snowball method. To collect data, a questionnaire was administered through face-to-face interviews. Gross margin analysis revealed that Bt maize is a more profitable option as compared to conventional maize seeds. Furthermore, econometric analyses, through use of the binomial regression model revealed that perceptions could be used to distinguish between users and non-users of Bt maize seed in the Eastern Cape Province. Results of inferential analysis indicate that the statistically significant variables at 5% level are gene erosion, quality and nutrition of products and food labels for Bt maize products perceptions. On the other hand, low expenses, seed market availability and farmers’ knowledge perceptions were significant at 10%. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of Bt maize adoption. In view of the research findings, several policy proposals are suggested to support policy formulation. Key words: Bacillus thuringiensis (Bt) maize, yieldgard, smallholder farmers, perceptions, Flagstaff, gross margin analysis, binomial logistic regression model, Eastern Cape Province.
- Full Text:
The efficacy and toxicological effects of aloe ferox mill. used in the management of constipation in Nkonkobe municipality of the Eastern Cape province, South Africa
- Authors: Wintola, Olubunmi Abosede A
- Date: 2011
- Subjects: Asphodelaceae -- South Africa -- Eastern Cape , Aloe -- South Africa -- Eastern Cape , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Constipation -- South Africa -- Eastern Cape , Poisonous plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Ethnobotany)
- Identifier: vital:11882 , http://hdl.handle.net/10353/485 , Asphodelaceae -- South Africa -- Eastern Cape , Aloe -- South Africa -- Eastern Cape , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Constipation -- South Africa -- Eastern Cape , Poisonous plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Description: Herbal remedies are commonly used in developing countries for the treatment of various diseases, including constipation. The rationale for utilizing medicinal plants for the treatment of diseases rested largely on the belief that they are safe and free of side effects. However, there is limited scientific evidence on the safety and efficacy of these herbal medicines to back up their continued therapeutic application. Aloe ferox Mill. (Aspodelaceae), known as Cape aloe, locally called ikhala is a medicinal plant used by the people of the Eastern Cape Province for the treatment of gastrointestinal problems and constipation. The plant is a perennial shrub with thick succulent leaves bearing brown thorns on the margin and bright orange flowers arranged in oval lanceolate. It occurs in all weather in bush veld, road side, gardens and undisturbed places. According to the ethnomedicinal information, A. ferox is used as purgative. This research project was therefore designed to evaluate its ability in the treatment of constipation and to investigate its possible toxicological property. At the beginning of this programme, a survey of plants used for the treatment of constipation in Nkonkobe Municipality of the Eastern Cape Province was carried out using a questionnaire, which was administered to herbalists, traditional healers and rural dwellers. The study revealed 10 plant species from 8 families that are used for the treatment of constipation in the province. Four plants, Aloe ferox Mill, Boophone distischa L.f Herb, Alepidea amatybica Eckl and Artemisia afra Jacq, were repeatedly mentioned. Based on the frequency of usage, perceived efficacy and availability to the rural dwellers and the traditional healers, Aloe ferox was the most commonly used of the plants for the treatment of constipation. The plant was thus, chosen for the study. The invivo laxative effect of the aqueous extract of Aloe ferox in the treatment of loperamide-induced constipation in Wistar rats was investigated at varying concentrations. The leaf extract at all the dosages investigated (50, 100 and 200 mg/kg body weight) improved intestinal motility, increased fecal volume and normalized body weight in the constipated rats. This was an indication of its laxative properties. However, the laxative property of the herb at 200 mg/kg body weight of the extract showed best efficacy and compares favourably well with senokot, a standard laxative drug. These findings have therefore, lent scientific credence to the folkloric use of the herb by the people of the Eastern Cape of South Africa as a laxative agent. Toxicological evaluation of aqueous leaf extract of Aloe ferox in loperamide-induced constipation was studied at 50, 100, and 200 mg/kg body weight. The oral administration of the extracts did not show any significant effect on the liver and kidney body weight ratios as well as the kidney and liver function indices. The extracts, at all the dosages investigated, did not alter the levels of creatinine, uric acid, urea, calcium and potassium ions. Similarly, the levels of total protein, albumin, bilirubin and gamma glutamyl transferase (GGT) were not significantly different from the control. The plant extract appreciably normalized the elevated activities of alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the untreated constipated rats following treatment with the extract. The extract did not show a significant effect on the hematological parameters except for the increase in the lymphocyte count in the untreated constipated rats, which was attenuated after administering the herb. ThThe available evidence in this study suggests that A. ferox may be safe as an oral remedy for constipation. Generally, the effect of the extract compared favourably well with senokot, a recommended drug for the treatment of constipation. The antioxidant activities against 1, 1 diphenyl- 2 picrylhydrazl (DPPH), 2,2’ – azinobis [3- ethylbenzothiazoline -6- sulfonic acid] diammonium salt (ABTS), hydrogen peroxide (H2O2), Nitric oxide (NO), lipid peroxidation and the ferric reducing agents were investigated spectrophotometrically. Alkaloids, saponins, tannins, total phenols, flavonoids, flavonols and proanthocyanidin were also determined to assess their effects on the antioxidants activity of this plant. The phytochemical content of the ethanol and acetone extracts were consistently high compared to other solvents extracts. The level of tannins was not significant (P > 0.05) as compared with other solvent extracts. The free radical scavenging activity of the extracts was high even at lower concentrations (0.025 mg/ml) except in DPPH and lipid peroxidation. The ferric reducing potential of the extracts was concentration dependent and significantly different from Vitamin C and butylated hydroxytoluene (BHT) that were used as standard drugs. The present study showed a high level of scavenging activity of the leaf extracts of Aloe ferox in all the solvent extracts. Both ethanol and methanolic extract showed potent antioxidant activities than acetone and aqueous extracts. The study indicated that the leaf extracts of Aloe ferox might be a valuable source of natural antioxidant for both medicine and food industries. A. ferox leaf consists of the gel, latex and mesophyll layer; however, the main active constituents of the latex and the leaf exudate of Aloe ferox are anthraquinones which are believed to be responsible for the laxative property. The laxative compound in Aloe ferox leaf extract was isolated and characterized by extracting the plant material in methanol and extract suspended in distilled water. Partitioning was done with n-hexane, ethyl acetate and butanol respectively and was co-spotted with the over-the-counter (OTC) laxative drugs. This led to the successive column chromatography and thin layer chromatography (TLC) of the most active ethyl acetate fraction on silica gel with benzene/ethanol/ammonia hydroxide (BEA: 90:10:1), ethyl acetate/methanol/water (EMW: 40:5.4:5) and chloroform/ethyl acetate/formic acid (CEF: 50:40:10) as the mobile phase. The successive chromatograph and TLC afforded two compounds of Rf 0.420 (blue) and 0.831 (yellow) with the over-the-counter (OTC) drugs. These compounds were not totally elucidated due to their small quantity and instability. However, hydroxyl (OH) and carboxyl groups (COOH) was established as common to the extracted compounds, which might be responsible for the biological activity recorded for the plant extract.
- Full Text:
- Authors: Wintola, Olubunmi Abosede A
- Date: 2011
- Subjects: Asphodelaceae -- South Africa -- Eastern Cape , Aloe -- South Africa -- Eastern Cape , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Constipation -- South Africa -- Eastern Cape , Poisonous plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Ethnobotany)
- Identifier: vital:11882 , http://hdl.handle.net/10353/485 , Asphodelaceae -- South Africa -- Eastern Cape , Aloe -- South Africa -- Eastern Cape , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Constipation -- South Africa -- Eastern Cape , Poisonous plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Description: Herbal remedies are commonly used in developing countries for the treatment of various diseases, including constipation. The rationale for utilizing medicinal plants for the treatment of diseases rested largely on the belief that they are safe and free of side effects. However, there is limited scientific evidence on the safety and efficacy of these herbal medicines to back up their continued therapeutic application. Aloe ferox Mill. (Aspodelaceae), known as Cape aloe, locally called ikhala is a medicinal plant used by the people of the Eastern Cape Province for the treatment of gastrointestinal problems and constipation. The plant is a perennial shrub with thick succulent leaves bearing brown thorns on the margin and bright orange flowers arranged in oval lanceolate. It occurs in all weather in bush veld, road side, gardens and undisturbed places. According to the ethnomedicinal information, A. ferox is used as purgative. This research project was therefore designed to evaluate its ability in the treatment of constipation and to investigate its possible toxicological property. At the beginning of this programme, a survey of plants used for the treatment of constipation in Nkonkobe Municipality of the Eastern Cape Province was carried out using a questionnaire, which was administered to herbalists, traditional healers and rural dwellers. The study revealed 10 plant species from 8 families that are used for the treatment of constipation in the province. Four plants, Aloe ferox Mill, Boophone distischa L.f Herb, Alepidea amatybica Eckl and Artemisia afra Jacq, were repeatedly mentioned. Based on the frequency of usage, perceived efficacy and availability to the rural dwellers and the traditional healers, Aloe ferox was the most commonly used of the plants for the treatment of constipation. The plant was thus, chosen for the study. The invivo laxative effect of the aqueous extract of Aloe ferox in the treatment of loperamide-induced constipation in Wistar rats was investigated at varying concentrations. The leaf extract at all the dosages investigated (50, 100 and 200 mg/kg body weight) improved intestinal motility, increased fecal volume and normalized body weight in the constipated rats. This was an indication of its laxative properties. However, the laxative property of the herb at 200 mg/kg body weight of the extract showed best efficacy and compares favourably well with senokot, a standard laxative drug. These findings have therefore, lent scientific credence to the folkloric use of the herb by the people of the Eastern Cape of South Africa as a laxative agent. Toxicological evaluation of aqueous leaf extract of Aloe ferox in loperamide-induced constipation was studied at 50, 100, and 200 mg/kg body weight. The oral administration of the extracts did not show any significant effect on the liver and kidney body weight ratios as well as the kidney and liver function indices. The extracts, at all the dosages investigated, did not alter the levels of creatinine, uric acid, urea, calcium and potassium ions. Similarly, the levels of total protein, albumin, bilirubin and gamma glutamyl transferase (GGT) were not significantly different from the control. The plant extract appreciably normalized the elevated activities of alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the untreated constipated rats following treatment with the extract. The extract did not show a significant effect on the hematological parameters except for the increase in the lymphocyte count in the untreated constipated rats, which was attenuated after administering the herb. ThThe available evidence in this study suggests that A. ferox may be safe as an oral remedy for constipation. Generally, the effect of the extract compared favourably well with senokot, a recommended drug for the treatment of constipation. The antioxidant activities against 1, 1 diphenyl- 2 picrylhydrazl (DPPH), 2,2’ – azinobis [3- ethylbenzothiazoline -6- sulfonic acid] diammonium salt (ABTS), hydrogen peroxide (H2O2), Nitric oxide (NO), lipid peroxidation and the ferric reducing agents were investigated spectrophotometrically. Alkaloids, saponins, tannins, total phenols, flavonoids, flavonols and proanthocyanidin were also determined to assess their effects on the antioxidants activity of this plant. The phytochemical content of the ethanol and acetone extracts were consistently high compared to other solvents extracts. The level of tannins was not significant (P > 0.05) as compared with other solvent extracts. The free radical scavenging activity of the extracts was high even at lower concentrations (0.025 mg/ml) except in DPPH and lipid peroxidation. The ferric reducing potential of the extracts was concentration dependent and significantly different from Vitamin C and butylated hydroxytoluene (BHT) that were used as standard drugs. The present study showed a high level of scavenging activity of the leaf extracts of Aloe ferox in all the solvent extracts. Both ethanol and methanolic extract showed potent antioxidant activities than acetone and aqueous extracts. The study indicated that the leaf extracts of Aloe ferox might be a valuable source of natural antioxidant for both medicine and food industries. A. ferox leaf consists of the gel, latex and mesophyll layer; however, the main active constituents of the latex and the leaf exudate of Aloe ferox are anthraquinones which are believed to be responsible for the laxative property. The laxative compound in Aloe ferox leaf extract was isolated and characterized by extracting the plant material in methanol and extract suspended in distilled water. Partitioning was done with n-hexane, ethyl acetate and butanol respectively and was co-spotted with the over-the-counter (OTC) laxative drugs. This led to the successive column chromatography and thin layer chromatography (TLC) of the most active ethyl acetate fraction on silica gel with benzene/ethanol/ammonia hydroxide (BEA: 90:10:1), ethyl acetate/methanol/water (EMW: 40:5.4:5) and chloroform/ethyl acetate/formic acid (CEF: 50:40:10) as the mobile phase. The successive chromatograph and TLC afforded two compounds of Rf 0.420 (blue) and 0.831 (yellow) with the over-the-counter (OTC) drugs. These compounds were not totally elucidated due to their small quantity and instability. However, hydroxyl (OH) and carboxyl groups (COOH) was established as common to the extracted compounds, which might be responsible for the biological activity recorded for the plant extract.
- Full Text:
The role of the state and the environment in indigenous livestock farming: a case study of Debe Marela, Middledrift area, Eastern Cape
- Authors: Hashe, Luvuyo E
- Date: 2011
- Subjects: Farmers -- South Africa -- Eastern Cape , Livestock -- South Africa -- Eastern Cape , Traditional farming -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Agriculture and politics -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPhil (Environmental Studies)
- Identifier: vital:11877 , http://hdl.handle.net/10353/372 , Farmers -- South Africa -- Eastern Cape , Livestock -- South Africa -- Eastern Cape , Traditional farming -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Agriculture and politics -- South Africa -- Eastern Cape
- Description: The study focused on the role of the State and the environment in indigenous livestock farming in Debe Marela in Middledrift. Although communal farmers in the area used ethnoveterinary medicines to treat and prevent animal diseases, they also widely used conventional medicines, as these often provided a remedy to animal diseases. The livestock farmers believed in indigenous knowledge which empowered them in using herbs to a certain extent, but the latter was preferred. The Department of Agriculture has featured as a support institution and although livestock farmers in the area have participated in and benefitted from state programmes, they believe that they needed more interventions such as visits from veterinary surgeons, Extension Officers and Animal Health Technicians. The study therefore attempts to address the gaps highlighted in the work of other researchers.
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- Authors: Hashe, Luvuyo E
- Date: 2011
- Subjects: Farmers -- South Africa -- Eastern Cape , Livestock -- South Africa -- Eastern Cape , Traditional farming -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Agriculture and politics -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPhil (Environmental Studies)
- Identifier: vital:11877 , http://hdl.handle.net/10353/372 , Farmers -- South Africa -- Eastern Cape , Livestock -- South Africa -- Eastern Cape , Traditional farming -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Agriculture and politics -- South Africa -- Eastern Cape
- Description: The study focused on the role of the State and the environment in indigenous livestock farming in Debe Marela in Middledrift. Although communal farmers in the area used ethnoveterinary medicines to treat and prevent animal diseases, they also widely used conventional medicines, as these often provided a remedy to animal diseases. The livestock farmers believed in indigenous knowledge which empowered them in using herbs to a certain extent, but the latter was preferred. The Department of Agriculture has featured as a support institution and although livestock farmers in the area have participated in and benefitted from state programmes, they believe that they needed more interventions such as visits from veterinary surgeons, Extension Officers and Animal Health Technicians. The study therefore attempts to address the gaps highlighted in the work of other researchers.
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Variability of the peak height of the ionospheric F2 layer over South Africa
- Authors: Mbambo, Makhangela Casey
- Date: 2011
- Subjects: Ionosphere -- South Africa , Ionosphere -- Observations , Ionosphere -- Research , Double layers (Astrophysics)
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: vital:11594 , http://hdl.handle.net/10353/446 , Ionosphere -- South Africa , Ionosphere -- Observations , Ionosphere -- Research , Double layers (Astrophysics)
- Description: Abstract This thesis will present an investigation into the variability of the maximum height of the ionospheric F2 layer, hmF2, with hour, season and latitude over the South African region. The dependence of hmF2 on solar and magnetic activity is also investigated. Data from three South African stations, namely Madimbo (22.4 S, 26.5 E), Grahamstown (33.3 S, 26.5 E) and Louisvale (28.5 S, 21.2 E) were used in this study. Initial results indicate that hmF2 shows a larger variability around midnight than during daytime for all the seasons. Monthly median values for hmF2 were used in all cases to illustrate the variability, and the International Reference Ionosphere (IRI) model has been used to investigate hmF2 predictability over South Africa. This research represents the initial steps towards a predictive model for the hmF2 parameter, with the long term aim of developing a new global hmF2 predictive model for the IRI. It is believed that this work will contribute signi cantly towards this aim through the understanding of the hmF2 parameter over a region that has not previously been investigated.
- Full Text:
- Authors: Mbambo, Makhangela Casey
- Date: 2011
- Subjects: Ionosphere -- South Africa , Ionosphere -- Observations , Ionosphere -- Research , Double layers (Astrophysics)
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: vital:11594 , http://hdl.handle.net/10353/446 , Ionosphere -- South Africa , Ionosphere -- Observations , Ionosphere -- Research , Double layers (Astrophysics)
- Description: Abstract This thesis will present an investigation into the variability of the maximum height of the ionospheric F2 layer, hmF2, with hour, season and latitude over the South African region. The dependence of hmF2 on solar and magnetic activity is also investigated. Data from three South African stations, namely Madimbo (22.4 S, 26.5 E), Grahamstown (33.3 S, 26.5 E) and Louisvale (28.5 S, 21.2 E) were used in this study. Initial results indicate that hmF2 shows a larger variability around midnight than during daytime for all the seasons. Monthly median values for hmF2 were used in all cases to illustrate the variability, and the International Reference Ionosphere (IRI) model has been used to investigate hmF2 predictability over South Africa. This research represents the initial steps towards a predictive model for the hmF2 parameter, with the long term aim of developing a new global hmF2 predictive model for the IRI. It is believed that this work will contribute signi cantly towards this aim through the understanding of the hmF2 parameter over a region that has not previously been investigated.
- Full Text: