Harvesting strategies of fuelwood and kraalwood users at Machibi : identifying the driving factors and feedbacks
- Authors: Scheepers, Kelly
- Date: 2008
- Subjects: Fuelwood -- South Africa -- Eastern Cape Forest ecology -- South Africa -- Eastern Cape Natural resources -- South Africa -- Eastern Cape Natural resources -- Management -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Landscape protection -- Economic aspects -- South Africa -- Eastern Cape Fuelwood consumption -- South Africa -- Eastern Cape Fuelwood consumption -- Economic aspects -- South Africa -- Eastern Cape Forests and forestry -- South Africa -- Eastern Cape Fuelwood conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4765 , http://hdl.handle.net/10962/d1007167
- Description: Forest and woodland ecosystems provide a variety of natural resources such as fuelwood, brushwood and kraal posts to local communities, as well as possess important cultural and spiritual value. However, many forests and woodlands worldwide have been unsustainably used and managed. Thus, under pressure from the international conservation community to recognise the importance of people's relationships with their surrounding natural environment, particularly for the natural resources it can provide, and given a move away from the management of forests and woodlands for sustained yields, and according to simple cause and effect models, in favour of systems approaches, South Africa has developed some of the most progressive natural resource management policies in the world. Nevertheless, for these policies to be sensitive to local contexts, there remains a need for a better understanding of how local people in different contexts, determine forest and woodland ecosystems to be of use to them, and what 'usefulness' means to different groups of resources users. This is a case study, which examines the role of fuelwood, brushwood and kraal posts in the rural livelihoods of the people of Machibi village, located in the Eastern Cape province of South Africa, through people's preferences for particular landscapes and species, accessed for these purposes, and the trade-offs people make between resource availability and resource accessibility. Key objectives of the study are to 1) determine the preferred landscapes and species for fuelwood, brushwood and kraal posts at Machibi, 2) determine the landscapes and species actually used for fuelwood, brushwood and kraal posts, and 3) with the help of a conceptual model, and using iterative modelling as a tool, determine the factors that influence people's harvesting strategies in terms of the costs and benefits associated with the different landscape and species options. On the basis of this knowledge, the study provides some guiding principles for the better use and management of these landscapes and species for fuelwood, brushwood and kraal posts. An innovative research approach and methodology that integrates social and ecological systems, works across disciplines, and draws on different types of knowledge is used to develop and test a conceptual model of the harvesting strategies of fuelwood and kraalwood users at Machibi. Participatory methods such as workshops, participatory resource mapping, ranking exercises and trend-lines were used to tap into local knowledge while plotless vegetation sampling and GIS maps were used to capture the scientific information. Results showed that people did not always use the landscapes and species they preferred. However, the local people did behave in a rational manner by weighing up the returns from harvesting and accessibility costs associated with the respective options available to them, before selecting the option(s) associated with the greatest net benefits. At the landscape level, people made trade-offs between the returns from harvesting and the accessibility costs of using particular landscapes in addition to costs associated with the physical work of harvesting fuelwood, brushwood or kraal posts from these landscapes. At the species level, people made trade-offs between the returns from harvesting and the accessibility costs of harvesting particular species for fuelwood, brushwood and kraal posts, or the costs of commercial alternatives. Costbenefit factors that influenced people's resource use patterns also differed across landscapes and species for fuelwood, brushwood and kraal posts, respectively. Consequently, a range of diverse and flexible management options and strategies is recommended for the wise use and management of these landscapes and species, focused on short, medium and long term goals. These strategies examine the use of cost - benefit incentives to influence people’s landscape and species use patterns.
- Full Text:
- Date Issued: 2008
- Authors: Scheepers, Kelly
- Date: 2008
- Subjects: Fuelwood -- South Africa -- Eastern Cape Forest ecology -- South Africa -- Eastern Cape Natural resources -- South Africa -- Eastern Cape Natural resources -- Management -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Landscape protection -- Economic aspects -- South Africa -- Eastern Cape Fuelwood consumption -- South Africa -- Eastern Cape Fuelwood consumption -- Economic aspects -- South Africa -- Eastern Cape Forests and forestry -- South Africa -- Eastern Cape Fuelwood conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4765 , http://hdl.handle.net/10962/d1007167
- Description: Forest and woodland ecosystems provide a variety of natural resources such as fuelwood, brushwood and kraal posts to local communities, as well as possess important cultural and spiritual value. However, many forests and woodlands worldwide have been unsustainably used and managed. Thus, under pressure from the international conservation community to recognise the importance of people's relationships with their surrounding natural environment, particularly for the natural resources it can provide, and given a move away from the management of forests and woodlands for sustained yields, and according to simple cause and effect models, in favour of systems approaches, South Africa has developed some of the most progressive natural resource management policies in the world. Nevertheless, for these policies to be sensitive to local contexts, there remains a need for a better understanding of how local people in different contexts, determine forest and woodland ecosystems to be of use to them, and what 'usefulness' means to different groups of resources users. This is a case study, which examines the role of fuelwood, brushwood and kraal posts in the rural livelihoods of the people of Machibi village, located in the Eastern Cape province of South Africa, through people's preferences for particular landscapes and species, accessed for these purposes, and the trade-offs people make between resource availability and resource accessibility. Key objectives of the study are to 1) determine the preferred landscapes and species for fuelwood, brushwood and kraal posts at Machibi, 2) determine the landscapes and species actually used for fuelwood, brushwood and kraal posts, and 3) with the help of a conceptual model, and using iterative modelling as a tool, determine the factors that influence people's harvesting strategies in terms of the costs and benefits associated with the different landscape and species options. On the basis of this knowledge, the study provides some guiding principles for the better use and management of these landscapes and species for fuelwood, brushwood and kraal posts. An innovative research approach and methodology that integrates social and ecological systems, works across disciplines, and draws on different types of knowledge is used to develop and test a conceptual model of the harvesting strategies of fuelwood and kraalwood users at Machibi. Participatory methods such as workshops, participatory resource mapping, ranking exercises and trend-lines were used to tap into local knowledge while plotless vegetation sampling and GIS maps were used to capture the scientific information. Results showed that people did not always use the landscapes and species they preferred. However, the local people did behave in a rational manner by weighing up the returns from harvesting and accessibility costs associated with the respective options available to them, before selecting the option(s) associated with the greatest net benefits. At the landscape level, people made trade-offs between the returns from harvesting and the accessibility costs of using particular landscapes in addition to costs associated with the physical work of harvesting fuelwood, brushwood or kraal posts from these landscapes. At the species level, people made trade-offs between the returns from harvesting and the accessibility costs of harvesting particular species for fuelwood, brushwood and kraal posts, or the costs of commercial alternatives. Costbenefit factors that influenced people's resource use patterns also differed across landscapes and species for fuelwood, brushwood and kraal posts, respectively. Consequently, a range of diverse and flexible management options and strategies is recommended for the wise use and management of these landscapes and species, focused on short, medium and long term goals. These strategies examine the use of cost - benefit incentives to influence people’s landscape and species use patterns.
- Full Text:
- Date Issued: 2008
Intersolid pyrotechnic reactions of silicon
- Authors: Rugunanan, Rajan Anil
- Date: 1992
- Subjects: Thermochemistry , Thermal analysis , Chemistry, Analytic , Chemistry, Organic , Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4527 , http://hdl.handle.net/10962/d1015571
- Description: A study of the role of different oxidants with silicon as the fuel in simple binary pyrotechnic compositions is reported. Several oxidants were examined, but only three (Sb₂0₃, Fe₂0₃ and Sn0₂) satisfied the restrictions that the combustion temperatures should be below the melting point of platinum/rhodium thermocouples (1760°C), that burning rates should not exceed the response of the thermocouples, and that burning should occur without significant mass-transport. A fourth oxidant, KN0₃, was selected on account of its low melting point and general importance as a pyrotechnic oxidant. The oxidation of silicon in the presence of either Sb₂0₃ or KN0₃ could be identified from thermal analysis curves. No thermal events were noted when Si/Sn0₂ and SiFe₂0₃ compositions were heated under similar conditions. The oxidation of Si powder in oxygen was also studied. All four binary systems sustained burning over a reasonably wide range of compositions. The range of burning rates measured (2 to 35 mm s⁻¹) depended on the oxidant used. Fe₂0₃ and Sb₂0₃ gave slow burning mixtures compared to Sn0₂ and to KN0₃ compositions with a high Si content. Burning rates generally increased with increasing specific surface area of silicon, but decreased in the presence of inert diluents and moisture. The burning rates of the Si/Fe₂0₃ and Si/Sn0₂ systems increased with increasing compaction of the samples. Kinetic parameters derived from the temperature proftles recorded during combustion were generally low (6 to 37 kJ mol⁻¹). This is in keeping with proposals that burning is diffusion controlled. The values of kinetic parameters derived from thermal analysis curves were considerably greater ( > 250 kJ mol⁻¹). Two other fuels, FeSi₇ and CaSi₂, gave similar thermal analysis curves when used instead of silicon. There were considerable differences in the burning rates for binary mixtures of these fuels compared to silicon. Ternary systems with two fuels or two oxidants showed that only limited interaction occurs during thermal analysis. The use of a second fuel or oxidant did, however, modify the burning behaviour considerably. Other techniques used in this study to probe the details of the reaction processes included bomb calorimetry, measurement of thermal conductivities, infrared spectroscopy, X-ray diffraction and scanning electron micoscropy.
- Full Text:
- Date Issued: 1992
- Authors: Rugunanan, Rajan Anil
- Date: 1992
- Subjects: Thermochemistry , Thermal analysis , Chemistry, Analytic , Chemistry, Organic , Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4527 , http://hdl.handle.net/10962/d1015571
- Description: A study of the role of different oxidants with silicon as the fuel in simple binary pyrotechnic compositions is reported. Several oxidants were examined, but only three (Sb₂0₃, Fe₂0₃ and Sn0₂) satisfied the restrictions that the combustion temperatures should be below the melting point of platinum/rhodium thermocouples (1760°C), that burning rates should not exceed the response of the thermocouples, and that burning should occur without significant mass-transport. A fourth oxidant, KN0₃, was selected on account of its low melting point and general importance as a pyrotechnic oxidant. The oxidation of silicon in the presence of either Sb₂0₃ or KN0₃ could be identified from thermal analysis curves. No thermal events were noted when Si/Sn0₂ and SiFe₂0₃ compositions were heated under similar conditions. The oxidation of Si powder in oxygen was also studied. All four binary systems sustained burning over a reasonably wide range of compositions. The range of burning rates measured (2 to 35 mm s⁻¹) depended on the oxidant used. Fe₂0₃ and Sb₂0₃ gave slow burning mixtures compared to Sn0₂ and to KN0₃ compositions with a high Si content. Burning rates generally increased with increasing specific surface area of silicon, but decreased in the presence of inert diluents and moisture. The burning rates of the Si/Fe₂0₃ and Si/Sn0₂ systems increased with increasing compaction of the samples. Kinetic parameters derived from the temperature proftles recorded during combustion were generally low (6 to 37 kJ mol⁻¹). This is in keeping with proposals that burning is diffusion controlled. The values of kinetic parameters derived from thermal analysis curves were considerably greater ( > 250 kJ mol⁻¹). Two other fuels, FeSi₇ and CaSi₂, gave similar thermal analysis curves when used instead of silicon. There were considerable differences in the burning rates for binary mixtures of these fuels compared to silicon. Ternary systems with two fuels or two oxidants showed that only limited interaction occurs during thermal analysis. The use of a second fuel or oxidant did, however, modify the burning behaviour considerably. Other techniques used in this study to probe the details of the reaction processes included bomb calorimetry, measurement of thermal conductivities, infrared spectroscopy, X-ray diffraction and scanning electron micoscropy.
- Full Text:
- Date Issued: 1992
An investigation into the development of environmental education as a field of practice in South African National Parks
- Authors: Taljaard, Sandra
- Date: 2009
- Subjects: Environmental education -- South Africa National parks and reserves -- South Africa Environmental education -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1603 , http://hdl.handle.net/10962/d1003485
- Description: This study looks at aspects of the development of environmental education in South African National Parks (SANParks), in relation to the emergence of national and organisational policy frameworks. In order to put current environmental education practices into context, the study firstly looks at the historical development line of environmental education in SANParks, as well as in the broader national context. This provides a framework within which the processes of change and development can be traced in terms of social, political and economic influences on an international and national front. The study finds that the promulgation of legislation, including the Constitution, National Acts and various other policies, reflected the trends of thinking and set the pace in a democratic South Africa, which led to the emergence of more explicit processes and refined policies. Popkewitz’s finding, that education emerged in modernity, is used in the study to illustrate this tendency. It finds that these changes in South Africa resulted in the establishment of more structured environmental education processes within SANParks, and led to the expansion, diversification and strengthening of environmental education as a field of practice over time. The study traces significant processes of recontextualisation of international and national environmental education related policies according to the framework established by Bernstein (1980). These processes of recontextualisation were followed in the formulation processes of SANParks policy and strategy documents in the period from 1999 to 2005, and resulted in an official pedagogic discourse for environmental education in SANParks. The study establishes a second level of recontextualisation, that is, the official pedagogic discourse of environmental education in SANParks is recontextualised to a pedagogic discourse of reproduction. The pedagogic discourse of reproduction relates to park practices, where contextualisation within park-based programmes appears to be strong. The park-based programmes resemble a ‘curriculum in practice’, which brings us to Cornbleth’s critical curriculum approach. The study utilises this approach to explore and explain the meaning of the critical perspective taken on curriculum construction and change efforts at park implementation level (Cornbleth, 1990). The study finds that the contextualisation of park programmes and practices lead to variety in park programmes, which adds richness to environmental education programmes and activities, and further highlights the fact that environmental education practices are prolific in national parks. The study also finds that historical and contextual processes associated with specific parks strongly characterise environmental education programmes and practices in those parks, and that partnership programmes, such as the Kids in Parks programme, contribute towards, and enhance the growth of environmental education as a specialised field of practice in SANParks. The study comments on the need for environmental education practices in SANParks to be reviewed and expanded in line with the contemporary approach towards the environment as a social construct of interacting components. These components include the biophysical, social, economic and political dimensions. The study also highlights the need for the recognition and acknowledgement of the long, historical development line of environmental education in SANParks in order to build on established structures in a holistic way. The study further determines a need for strong leadership to successfully expand this specialised field of practice and encourages a participatory approach in the review and further development of this field of practice in SANParks. The study ultimately finds that environmental education in SANParks has a long and rich development profile, which has placed it in a strong position for further development. However, it concludes that there is a great need for a rejuvenated approach, which requires expert knowledge, professionalism and broad based networking approach to enable meaningful expansion within this specialised field of practice.
- Full Text:
- Date Issued: 2009
- Authors: Taljaard, Sandra
- Date: 2009
- Subjects: Environmental education -- South Africa National parks and reserves -- South Africa Environmental education -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1603 , http://hdl.handle.net/10962/d1003485
- Description: This study looks at aspects of the development of environmental education in South African National Parks (SANParks), in relation to the emergence of national and organisational policy frameworks. In order to put current environmental education practices into context, the study firstly looks at the historical development line of environmental education in SANParks, as well as in the broader national context. This provides a framework within which the processes of change and development can be traced in terms of social, political and economic influences on an international and national front. The study finds that the promulgation of legislation, including the Constitution, National Acts and various other policies, reflected the trends of thinking and set the pace in a democratic South Africa, which led to the emergence of more explicit processes and refined policies. Popkewitz’s finding, that education emerged in modernity, is used in the study to illustrate this tendency. It finds that these changes in South Africa resulted in the establishment of more structured environmental education processes within SANParks, and led to the expansion, diversification and strengthening of environmental education as a field of practice over time. The study traces significant processes of recontextualisation of international and national environmental education related policies according to the framework established by Bernstein (1980). These processes of recontextualisation were followed in the formulation processes of SANParks policy and strategy documents in the period from 1999 to 2005, and resulted in an official pedagogic discourse for environmental education in SANParks. The study establishes a second level of recontextualisation, that is, the official pedagogic discourse of environmental education in SANParks is recontextualised to a pedagogic discourse of reproduction. The pedagogic discourse of reproduction relates to park practices, where contextualisation within park-based programmes appears to be strong. The park-based programmes resemble a ‘curriculum in practice’, which brings us to Cornbleth’s critical curriculum approach. The study utilises this approach to explore and explain the meaning of the critical perspective taken on curriculum construction and change efforts at park implementation level (Cornbleth, 1990). The study finds that the contextualisation of park programmes and practices lead to variety in park programmes, which adds richness to environmental education programmes and activities, and further highlights the fact that environmental education practices are prolific in national parks. The study also finds that historical and contextual processes associated with specific parks strongly characterise environmental education programmes and practices in those parks, and that partnership programmes, such as the Kids in Parks programme, contribute towards, and enhance the growth of environmental education as a specialised field of practice in SANParks. The study comments on the need for environmental education practices in SANParks to be reviewed and expanded in line with the contemporary approach towards the environment as a social construct of interacting components. These components include the biophysical, social, economic and political dimensions. The study also highlights the need for the recognition and acknowledgement of the long, historical development line of environmental education in SANParks in order to build on established structures in a holistic way. The study further determines a need for strong leadership to successfully expand this specialised field of practice and encourages a participatory approach in the review and further development of this field of practice in SANParks. The study ultimately finds that environmental education in SANParks has a long and rich development profile, which has placed it in a strong position for further development. However, it concludes that there is a great need for a rejuvenated approach, which requires expert knowledge, professionalism and broad based networking approach to enable meaningful expansion within this specialised field of practice.
- Full Text:
- Date Issued: 2009
The diamondback moth, Plutella xylostella (L.), (Lepidoptera: Plutellidae) and its biological control in the Eastern Cape Province, South Africa
- Authors: Smith, Tamara Jane
- Date: 2003
- Subjects: Plutellidae Plutellidae -- South Africa -- Eastern Cape Insect pests -- Biological control -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5626 , http://hdl.handle.net/10962/d1004742
- Description: The diamondback moth, Plutella xylostella (L.), is a pest on crucifer crops worldwide, damaging the leaves, florets and seed pods of many crucifers including cabbage, cauliflower, broccoli and canola. It has been controlled using broad-spectrum insecticides, but this has led to a rapid build-up of insecticide resistance. In the Grahamstown area of the Eastern Cape Province, South Africa, diamondback moth showed resistance to cypermethrin (a pyrethroid) on commercially grown cabbages. Therefore it is imperative that other methods of control be adopted, including both cultural control and biological control using parasitoids, and that these are incorporated into an Integrated Pest Management (IPM) programme. The diamondback moth and its parasitoids were monitored weekly from April 1997 to November 1999 at three sites near Grahamstown. One site was a commercial farm with an active insecticide spraying program; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May). Nine species of parasitoids were associated with the diamondback moth, with abundances being highest over spring and early summer (September to December). Cotesia plutellae (Kurdjumov) dominated the sprayed site, while the unsprayed sites yielded a complex of parasitoids, including C. plutellae, Diadegma mollipla (Holmgren), Diadromus collaris Gravenhorst and Oomyzus sokolowsldi (Kurdjumov). Parasitism levels ranged between 10 and 90%. There was a large amount of site-to-site and year-to-year variation. Parasitoids were an effective mortality factor against the diamondback moth. The effects of temperature on development and mortality, and of field size and non-crop plants on the distribution of diamondback moth and its parasitoids, were investigated. The results show that high temperatures can depress pest populations, and that the size and surroundings of fields can be manipulated to improve cultural control of the diamondback moth. Suggestions for effective rPM in the Eastern Cape Province include a reduction in insecticide applications, the use of bioinsecticides, for example Bacillus thuringiensis Berliner (Bt) and the encouragement of indigenous parasitoids by planting suitable nectar sources. Cultural control methods are also important and involve removal of cabbage refuse after harvest, management of wild crucifers around cabbage fields, scouting and monitoring the moth population and determining the optimal field size to assist with control by parasitoids.
- Full Text:
- Date Issued: 2003
- Authors: Smith, Tamara Jane
- Date: 2003
- Subjects: Plutellidae Plutellidae -- South Africa -- Eastern Cape Insect pests -- Biological control -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5626 , http://hdl.handle.net/10962/d1004742
- Description: The diamondback moth, Plutella xylostella (L.), is a pest on crucifer crops worldwide, damaging the leaves, florets and seed pods of many crucifers including cabbage, cauliflower, broccoli and canola. It has been controlled using broad-spectrum insecticides, but this has led to a rapid build-up of insecticide resistance. In the Grahamstown area of the Eastern Cape Province, South Africa, diamondback moth showed resistance to cypermethrin (a pyrethroid) on commercially grown cabbages. Therefore it is imperative that other methods of control be adopted, including both cultural control and biological control using parasitoids, and that these are incorporated into an Integrated Pest Management (IPM) programme. The diamondback moth and its parasitoids were monitored weekly from April 1997 to November 1999 at three sites near Grahamstown. One site was a commercial farm with an active insecticide spraying program; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May). Nine species of parasitoids were associated with the diamondback moth, with abundances being highest over spring and early summer (September to December). Cotesia plutellae (Kurdjumov) dominated the sprayed site, while the unsprayed sites yielded a complex of parasitoids, including C. plutellae, Diadegma mollipla (Holmgren), Diadromus collaris Gravenhorst and Oomyzus sokolowsldi (Kurdjumov). Parasitism levels ranged between 10 and 90%. There was a large amount of site-to-site and year-to-year variation. Parasitoids were an effective mortality factor against the diamondback moth. The effects of temperature on development and mortality, and of field size and non-crop plants on the distribution of diamondback moth and its parasitoids, were investigated. The results show that high temperatures can depress pest populations, and that the size and surroundings of fields can be manipulated to improve cultural control of the diamondback moth. Suggestions for effective rPM in the Eastern Cape Province include a reduction in insecticide applications, the use of bioinsecticides, for example Bacillus thuringiensis Berliner (Bt) and the encouragement of indigenous parasitoids by planting suitable nectar sources. Cultural control methods are also important and involve removal of cabbage refuse after harvest, management of wild crucifers around cabbage fields, scouting and monitoring the moth population and determining the optimal field size to assist with control by parasitoids.
- Full Text:
- Date Issued: 2003
Stratigraphy, geochemistry and origin of the manganese ore deposit in Carletonville, North West province of South Africa
- Authors: Pharoe, Benedict Kinshasa
- Date: 2015
- Subjects: Geology, Stratigraphic Geology--South Africa Geochemistry--South Africa
- Language: English
- Type: Thesis , Masters , Geology
- Identifier: http://hdl.handle.net/10353/11641 , vital:39092
- Description: The Carletonville manganese ore-deposit is a Neogene weathered nodule deposit which was developed on the Early Proterozoic Malmani dolomite succession of the Transvaal Supergroup in Carletonville area, North-West Province, South Africa. The deposits were formed from surficial weathering of the underlying Mn-rich dolomites of the Malmani Subgroup and some were formed from weathered Mn-rich Tertiary alluvial-fluvial sediments. These deposits are currently mineralized and hosted in modern Mn-Fe rich soil profiles and occurs at shallow depths, thus the ore is suitable to be mined by open-cast mining. The study dealt with the stratigraphy, petrology, geochemistry, diagenesis and origin of the ore-deposit. The stratigraphic profile of the manganese ore-deposit was subdivided into 8 zones, namely the (A, B, C, D, E, F, G, and H) zones from the surface downwards. On the basis of variation in mineralogical and chemical composition, nodule grain sizes and the zonation colour, the above mentioned zones were further integrated into the Upper (A and B), Middle (C, D and E) and Lower (F, G and H) Zone, with the I zone, the basement zone, representing the underlying Malmani Subgroup stromatolitic dolomite. The Upper Zone represents organic rich, fine grain silty soil which caps the stratigraphic succession in the mine area. Mineralogically, these zones are depleted in manganese and comprises of hematite, kaolinite, micas and quartz grains, with Mn-Fe coated terrigenous clasts concentrated at the lowermost portion of the B-zone along the contact with the underlying zones. The Middle Zone is characteristically medium to fine in grain sizes with reddish colour due to intense weathering of iron minerals to hematite and is depleted in Ca, Na and Mg bearing minerals as a result of dissolution and leaching and is highly concentrated in quartz and caliche fragments. The Lower Zone is coarse grained with dark, reddish-brown colour. The Middle and Lower Zones comprise mainly of Mn and Fe oxides, clays, quartz, limonite, micas and caliche patches. The concentration of manganese is, however, not consistent in these zones from one borehole to the next, it deviates with topography and depth. The overall stratigraphic succession in the mine area can be described as characterizing of basal stromatolitic dolomite of the Malmani Subgroup, overlain by zone of black, powder-like manganiferous wad which is in turn overlain by weathered Mn-rich Tertiary alluvial-fluvial sediments hosting manganiferous nodules. The whole succession is covered by Quaternary sands. The studies undertaken on grain size analysis for the determination of variation in nodule grain sizes with increasing depth along the profile has indicated a perfect variation trend in grain sizes, where the underlying Lower Zone characterizes of coarse grain fraction whilst the overlying Middle Zone is mainly medium to fine grained and the Upper Zone comprise of very fine silt soil. Statistical parameters were used to classify these sediments under Udden-Wentworth grain size classification scheme. Based on these parameters the samples were classified as pebbles and/or gravel on GRADISTAT program and were found to be moderately to poorly sorted, positively skewed with moderate kurtosis and displays a bimodal distribution. Mineralogical analysis with X-Ray Diffraction and petrographic studies indicates that cryptomelane (KMn8 O16) is the major manganese mineral, whereas pyrolusite occurs as a minor manganese mineral in the mine. Other mineral constituents include hematite/goethite, clay minerals, muscovite, quartz, calcite, limonite with minor amount of heavy minerals. The modal composition studies carried out on the terrigenous clasts which are coated on surface by Mn-Fe oxide concentric laminae indicated their nature to be sub-arkoses and quartz arenites. These clasts are found to occur in association with manganiferous nodules in the mine area, with high concentration experienced at the uppermost portion of the profile below the top soil. The provenance studies indicates the source of these terrigenous sediments from cratonic interior to recycle orogen at low plains with a temperate and subhumid climate and on tropical, humid conditions within an area of moderate to low relief. Based on the geochemical studies, different manganese classification schemes were adopted in this study and inferences were made from geochemical data which indicated supergene and hydrogenous source of the Carletonville manganese nodules suggesting precipitation from weathering residues of Malmani dolomite at passive continental margin of tectonic provenance, with temperate and tropical to humid climatic conditions. The diagenetic features were broadly divided into early, mid and uplift diagenetic stage. Early stage includes sediment consolidation which characterized of cementation and neomorphism in carbonate sediments. This period was followed by mid (burial diagenesis) stage which brought about an increase in tightness of grain packing, loss of pore spaces and thinning of beds due to weight of overlying sediments and selective dissolution of framework grains. Mineral dissolution and replacement were common factors during this stage. In the last diagenetic stage, rocks were uplifted, weathered and unroofed by erosion bringing mineral assemblage including newly formed diagenetic minerals into environment of low temperature and pressure, and high oxygen environment.
- Full Text:
- Date Issued: 2015
- Authors: Pharoe, Benedict Kinshasa
- Date: 2015
- Subjects: Geology, Stratigraphic Geology--South Africa Geochemistry--South Africa
- Language: English
- Type: Thesis , Masters , Geology
- Identifier: http://hdl.handle.net/10353/11641 , vital:39092
- Description: The Carletonville manganese ore-deposit is a Neogene weathered nodule deposit which was developed on the Early Proterozoic Malmani dolomite succession of the Transvaal Supergroup in Carletonville area, North-West Province, South Africa. The deposits were formed from surficial weathering of the underlying Mn-rich dolomites of the Malmani Subgroup and some were formed from weathered Mn-rich Tertiary alluvial-fluvial sediments. These deposits are currently mineralized and hosted in modern Mn-Fe rich soil profiles and occurs at shallow depths, thus the ore is suitable to be mined by open-cast mining. The study dealt with the stratigraphy, petrology, geochemistry, diagenesis and origin of the ore-deposit. The stratigraphic profile of the manganese ore-deposit was subdivided into 8 zones, namely the (A, B, C, D, E, F, G, and H) zones from the surface downwards. On the basis of variation in mineralogical and chemical composition, nodule grain sizes and the zonation colour, the above mentioned zones were further integrated into the Upper (A and B), Middle (C, D and E) and Lower (F, G and H) Zone, with the I zone, the basement zone, representing the underlying Malmani Subgroup stromatolitic dolomite. The Upper Zone represents organic rich, fine grain silty soil which caps the stratigraphic succession in the mine area. Mineralogically, these zones are depleted in manganese and comprises of hematite, kaolinite, micas and quartz grains, with Mn-Fe coated terrigenous clasts concentrated at the lowermost portion of the B-zone along the contact with the underlying zones. The Middle Zone is characteristically medium to fine in grain sizes with reddish colour due to intense weathering of iron minerals to hematite and is depleted in Ca, Na and Mg bearing minerals as a result of dissolution and leaching and is highly concentrated in quartz and caliche fragments. The Lower Zone is coarse grained with dark, reddish-brown colour. The Middle and Lower Zones comprise mainly of Mn and Fe oxides, clays, quartz, limonite, micas and caliche patches. The concentration of manganese is, however, not consistent in these zones from one borehole to the next, it deviates with topography and depth. The overall stratigraphic succession in the mine area can be described as characterizing of basal stromatolitic dolomite of the Malmani Subgroup, overlain by zone of black, powder-like manganiferous wad which is in turn overlain by weathered Mn-rich Tertiary alluvial-fluvial sediments hosting manganiferous nodules. The whole succession is covered by Quaternary sands. The studies undertaken on grain size analysis for the determination of variation in nodule grain sizes with increasing depth along the profile has indicated a perfect variation trend in grain sizes, where the underlying Lower Zone characterizes of coarse grain fraction whilst the overlying Middle Zone is mainly medium to fine grained and the Upper Zone comprise of very fine silt soil. Statistical parameters were used to classify these sediments under Udden-Wentworth grain size classification scheme. Based on these parameters the samples were classified as pebbles and/or gravel on GRADISTAT program and were found to be moderately to poorly sorted, positively skewed with moderate kurtosis and displays a bimodal distribution. Mineralogical analysis with X-Ray Diffraction and petrographic studies indicates that cryptomelane (KMn8 O16) is the major manganese mineral, whereas pyrolusite occurs as a minor manganese mineral in the mine. Other mineral constituents include hematite/goethite, clay minerals, muscovite, quartz, calcite, limonite with minor amount of heavy minerals. The modal composition studies carried out on the terrigenous clasts which are coated on surface by Mn-Fe oxide concentric laminae indicated their nature to be sub-arkoses and quartz arenites. These clasts are found to occur in association with manganiferous nodules in the mine area, with high concentration experienced at the uppermost portion of the profile below the top soil. The provenance studies indicates the source of these terrigenous sediments from cratonic interior to recycle orogen at low plains with a temperate and subhumid climate and on tropical, humid conditions within an area of moderate to low relief. Based on the geochemical studies, different manganese classification schemes were adopted in this study and inferences were made from geochemical data which indicated supergene and hydrogenous source of the Carletonville manganese nodules suggesting precipitation from weathering residues of Malmani dolomite at passive continental margin of tectonic provenance, with temperate and tropical to humid climatic conditions. The diagenetic features were broadly divided into early, mid and uplift diagenetic stage. Early stage includes sediment consolidation which characterized of cementation and neomorphism in carbonate sediments. This period was followed by mid (burial diagenesis) stage which brought about an increase in tightness of grain packing, loss of pore spaces and thinning of beds due to weight of overlying sediments and selective dissolution of framework grains. Mineral dissolution and replacement were common factors during this stage. In the last diagenetic stage, rocks were uplifted, weathered and unroofed by erosion bringing mineral assemblage including newly formed diagenetic minerals into environment of low temperature and pressure, and high oxygen environment.
- Full Text:
- Date Issued: 2015
An investigation into the feasibility of incorporating didanosine into innovative solid lipid nanocarriers
- Authors: Wa Kasongo, Kasongo
- Date: 2010
- Subjects: Antiretroviral agents HIV infections -- Drug testing Didanosine Nanoparticles Drug delivery systems Nanostructured materials Lipids -- Therapeutic use
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3800 , http://hdl.handle.net/10962/d1003278
- Description: The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).
- Full Text:
- Date Issued: 2010
- Authors: Wa Kasongo, Kasongo
- Date: 2010
- Subjects: Antiretroviral agents HIV infections -- Drug testing Didanosine Nanoparticles Drug delivery systems Nanostructured materials Lipids -- Therapeutic use
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3800 , http://hdl.handle.net/10962/d1003278
- Description: The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).
- Full Text:
- Date Issued: 2010
Reaction phenomena between Karroo Dolerite and cave sandstone xenoliths in the Bird's River complex
- Authors: Kenyon, A K
- Date: 1976
- Subjects: Volcanic ash, tuff, etc , Igneous rocks -- Inclusions , Sandstone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4996 , http://hdl.handle.net/10962/d1005608
- Description: Mapping of the north-eastern portion of the Bird1s River Complex revealed that two large xenoliths composed of pyroclastic rocks and sandstone of the Cave Sandstone Stage have reacted with the dolerite. All the reaction phenomena normally associated with Karroo Dolerite are encountered. These are: (a) Metasomatism during the stage of iron enrichment of the dolerite with the production of a pyroxene-plagioclase metasomatic granophyre (b) Metasomatism during the stage of alkali enrichment of the dolerite with the production of a potassium feldspar adinole C c) Assimilation 'vi th the production of contaminated doleri tes Cd) Fusion 'vi th the production of glassy rocks including buchi tes (e) The production of rheomorphic veins
- Full Text:
- Date Issued: 1976
- Authors: Kenyon, A K
- Date: 1976
- Subjects: Volcanic ash, tuff, etc , Igneous rocks -- Inclusions , Sandstone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4996 , http://hdl.handle.net/10962/d1005608
- Description: Mapping of the north-eastern portion of the Bird1s River Complex revealed that two large xenoliths composed of pyroclastic rocks and sandstone of the Cave Sandstone Stage have reacted with the dolerite. All the reaction phenomena normally associated with Karroo Dolerite are encountered. These are: (a) Metasomatism during the stage of iron enrichment of the dolerite with the production of a pyroxene-plagioclase metasomatic granophyre (b) Metasomatism during the stage of alkali enrichment of the dolerite with the production of a potassium feldspar adinole C c) Assimilation 'vi th the production of contaminated doleri tes Cd) Fusion 'vi th the production of glassy rocks including buchi tes (e) The production of rheomorphic veins
- Full Text:
- Date Issued: 1976
Aspects of the transdermal permeation and analysis of betamethasone 17-valerate
- Authors: Smith, Eric W
- Date: 1988
- Subjects: Transdermal medication Skin absorption Dermatologic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3815 , http://hdl.handle.net/10962/d1004741
- Description: The current world-wide interest in transdermal drug delivery makes the prospect of valid in vitro diffusion cell methodology highly attractive. A new laboratory diffusion cell has been designed and constructed based on theoretical principles and practical permeation reports surveyed in recent literature, and has been applied to the monitoring of betamethasone 17-valerate permeation. The cell performance has been validated with respect to hydrodynamic mixing efficiency and temperature of the receptor phase. The steady-state permeation of this corticosteroid has been monitored through various synthetic and animal membranes in order to select the most appropriate media for in vitro study. The permeation of betamethasone 17-valerate has been monitored from various types of commercial and extemporaneously prepared semisolid topical formulation (cream, lotion, ointment and scalp application), through silicone membrane, human and weanling pig stratum corneum, and full thickness hairless mouse skin, and these in vitro results have been compared to data from in vivo blanching assays, using the same formulations, in an attempt to correlate the findings. This experimental methodology has necessitated the development of ancillary analytical techniques. A column-switching high-performance liquid chromatographic method has been developed for the rapid on-line clean-up and analysis of betamethasone 17-valerate contained in the various topical formulations, which minimizes sample handling and extraction procedures. The method has been modified for the analysis of this corticosteroid in the isopropyl myristate receptor phase used in the in vitro permeation experiments, and scintillation counting of tritium-labelled water has been used to verify the integrity of the animal membranes. The comparison of in vitro permeation and in vivo blanching results indicate good correlation of the data in certain instances. The closest correlations have been observed when the human stratum corneum has been used in vitro and these results are compared to data from the occluded mode of the blanching assay. The results of the porcine and murine media have also correlated with the human in vivo data, whereas the silicone membrane appears applicable only in certain in vitro experiments. The results indicate that valid, comparative percutaneous absorption data may be obtained in vitro by using a well designed, validated diffusion cell system.
- Full Text:
- Date Issued: 1988
- Authors: Smith, Eric W
- Date: 1988
- Subjects: Transdermal medication Skin absorption Dermatologic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3815 , http://hdl.handle.net/10962/d1004741
- Description: The current world-wide interest in transdermal drug delivery makes the prospect of valid in vitro diffusion cell methodology highly attractive. A new laboratory diffusion cell has been designed and constructed based on theoretical principles and practical permeation reports surveyed in recent literature, and has been applied to the monitoring of betamethasone 17-valerate permeation. The cell performance has been validated with respect to hydrodynamic mixing efficiency and temperature of the receptor phase. The steady-state permeation of this corticosteroid has been monitored through various synthetic and animal membranes in order to select the most appropriate media for in vitro study. The permeation of betamethasone 17-valerate has been monitored from various types of commercial and extemporaneously prepared semisolid topical formulation (cream, lotion, ointment and scalp application), through silicone membrane, human and weanling pig stratum corneum, and full thickness hairless mouse skin, and these in vitro results have been compared to data from in vivo blanching assays, using the same formulations, in an attempt to correlate the findings. This experimental methodology has necessitated the development of ancillary analytical techniques. A column-switching high-performance liquid chromatographic method has been developed for the rapid on-line clean-up and analysis of betamethasone 17-valerate contained in the various topical formulations, which minimizes sample handling and extraction procedures. The method has been modified for the analysis of this corticosteroid in the isopropyl myristate receptor phase used in the in vitro permeation experiments, and scintillation counting of tritium-labelled water has been used to verify the integrity of the animal membranes. The comparison of in vitro permeation and in vivo blanching results indicate good correlation of the data in certain instances. The closest correlations have been observed when the human stratum corneum has been used in vitro and these results are compared to data from the occluded mode of the blanching assay. The results of the porcine and murine media have also correlated with the human in vivo data, whereas the silicone membrane appears applicable only in certain in vitro experiments. The results indicate that valid, comparative percutaneous absorption data may be obtained in vitro by using a well designed, validated diffusion cell system.
- Full Text:
- Date Issued: 1988
Visual art education narratives in context: contribution by offenders in one correctional facility in the Eastern Cape
- Authors: Potelwa, Siphe
- Date: 2019
- Subjects: Adult learning
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16665 , vital:40741
- Description: This study sought a solution to close the gap of visual art education narratives under recognition and not taken into consideration in correctional facilities. The researcher’s original contribution to knowledge was to provide the theoretical framework as the lens of this study. This research questions the universal objective of how visual art education narratives contribute to the context of the offender’s voice of selfexpression, self-worth, personal identity and human right in a democratic South African as citizens of society. The aim and objectives were to determine if transformation is evidenced through visual art education and ascertain personal identity as a human right and self-worth for an offender. This study was a qualitative research in which perceptions of offenders in visual art education programmes are investigated in-depth regarding the programmes addressing rehabilitation, selfexpression, self-fulfilment and personal development. Eight respondents participated in this study voluntarily. The selection of respondents in this study was through purposeful sampling. Individual interviews, focus group interviews, observation, document review, open-ended interviews, and website data of correctional services were conducted to collect data. The target participants for this qualitative study were permanent employees of Department of Correctional Services and offenders found guilty of murder and sexual abuse against women and children enrolled in a programme of art education. This study found no anticipated risks to voluntary participation in this research, and the study was free from psychological harm. The study contributed and found adult learners bringing their experience and knowledge into creative artwork skills as voice of self-expression, self-worth and rehabilitation. Analysis of data and interpretation of findings revealed the results that visual art education narratives programme brought self-worth, self-expression, selfdevelopment, self-fulfilment, discipline, prevents conflict, boredom and offender recidivism. This study conclusion stressed, an approach to the solution of the adult learning visual art education in correctional centre were problems identified. It is recommended that the correctional facility, interactive relationships with other departments, and commitment should be implemented without delay
- Full Text:
- Date Issued: 2019
- Authors: Potelwa, Siphe
- Date: 2019
- Subjects: Adult learning
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16665 , vital:40741
- Description: This study sought a solution to close the gap of visual art education narratives under recognition and not taken into consideration in correctional facilities. The researcher’s original contribution to knowledge was to provide the theoretical framework as the lens of this study. This research questions the universal objective of how visual art education narratives contribute to the context of the offender’s voice of selfexpression, self-worth, personal identity and human right in a democratic South African as citizens of society. The aim and objectives were to determine if transformation is evidenced through visual art education and ascertain personal identity as a human right and self-worth for an offender. This study was a qualitative research in which perceptions of offenders in visual art education programmes are investigated in-depth regarding the programmes addressing rehabilitation, selfexpression, self-fulfilment and personal development. Eight respondents participated in this study voluntarily. The selection of respondents in this study was through purposeful sampling. Individual interviews, focus group interviews, observation, document review, open-ended interviews, and website data of correctional services were conducted to collect data. The target participants for this qualitative study were permanent employees of Department of Correctional Services and offenders found guilty of murder and sexual abuse against women and children enrolled in a programme of art education. This study found no anticipated risks to voluntary participation in this research, and the study was free from psychological harm. The study contributed and found adult learners bringing their experience and knowledge into creative artwork skills as voice of self-expression, self-worth and rehabilitation. Analysis of data and interpretation of findings revealed the results that visual art education narratives programme brought self-worth, self-expression, selfdevelopment, self-fulfilment, discipline, prevents conflict, boredom and offender recidivism. This study conclusion stressed, an approach to the solution of the adult learning visual art education in correctional centre were problems identified. It is recommended that the correctional facility, interactive relationships with other departments, and commitment should be implemented without delay
- Full Text:
- Date Issued: 2019
Synthesis and evaluation of novel HIV-1 enzyme inhibitors
- Olomola, Temitope Oloruntoba
- Authors: Olomola, Temitope Oloruntoba
- Date: 2011
- Subjects: HIV infections -- Treatment HIV infections -- Chemotherapy HIV (Viruses) Enzyme inhibitors AZT (Drug) Reverse transcriptase Proteolytic enzymes Ligands Psoralens Resorcinol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4369 , http://hdl.handle.net/10962/d1005034
- Description: This study has involved the design, synthesis and evaluation of novel HIV-1 enzyme inhibitors accessed by synthetic elaboration of Baylis-Hillman adducts. Several series of complex coumarin-AZT and cinnamate ester-AZT conjugates have been prepared, in high yields, by exploiting the click reaction between appropriate Baylis-Hillman derived precursors and azidothymidine (AZT), all of which have been fully characterised using spectroscopic techniques. These conjugates, designed as potential dual-action HIV-1 inhibitors, were tested against the appropriate HIV-1 enzymes, i.e. HIV-1 reverse transcriptase and protease or HIV-1 reverse transcriptase and integrase. A number of the ligands have exhibited % inhibition levels and IC50 values comparable to drugs in clinical use, permitting their identification as lead compounds for the development of novel dual-action inhibitors. In silico docking of selected ligands into the active sites of the respective enzymes has provided useful insight into binding conformations and potential hydrogen-bonding interactions with active-site amino acid residues. A series of furocoumarin carboxamide derivatives have been synthesised in four steps starting from resorcinol and these compounds have also been tested for HIV-1 integrase inhibition activity. The structures of unexpected products isolated from Aza-Baylis-Hillman reactions of N-tosylaldimines have been elucidated by spectroscopic analysis, and confirmed by single crystal X-ray analysis. A mechanism for what appears to be an unprecedented transformation has been proposed. Microwave-assisted SeO₂ oxidation of Baylis-Hillman-derived 3-methylcoumarins has provided convenient and efficient access to coumarin-3-carbaldehydes, and a pilot study has revealed the potential of these coumarin-3-carbaldehydes as scaffolds for the construction of tricyclic compounds. The HCl-catalysed reaction of tert-butyl acrylate derived Baylis-Hillman adducts has been shown to afford 3-(chloromethyl)coumarins and α-(chloromethyl)cinnamic acids, the Zstereochemistry of the latter being established by X-ray crystallography. ¹H NMR-based experimental kinetic and DFT-level theoretical studies have been undertaken to establish the reaction sequence and other mechanistic details. Base-catalysed cyclisation on the other hand, has been shown to afford 2H-chromene rather than coumarin derivatives.
- Full Text:
- Date Issued: 2011
- Authors: Olomola, Temitope Oloruntoba
- Date: 2011
- Subjects: HIV infections -- Treatment HIV infections -- Chemotherapy HIV (Viruses) Enzyme inhibitors AZT (Drug) Reverse transcriptase Proteolytic enzymes Ligands Psoralens Resorcinol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4369 , http://hdl.handle.net/10962/d1005034
- Description: This study has involved the design, synthesis and evaluation of novel HIV-1 enzyme inhibitors accessed by synthetic elaboration of Baylis-Hillman adducts. Several series of complex coumarin-AZT and cinnamate ester-AZT conjugates have been prepared, in high yields, by exploiting the click reaction between appropriate Baylis-Hillman derived precursors and azidothymidine (AZT), all of which have been fully characterised using spectroscopic techniques. These conjugates, designed as potential dual-action HIV-1 inhibitors, were tested against the appropriate HIV-1 enzymes, i.e. HIV-1 reverse transcriptase and protease or HIV-1 reverse transcriptase and integrase. A number of the ligands have exhibited % inhibition levels and IC50 values comparable to drugs in clinical use, permitting their identification as lead compounds for the development of novel dual-action inhibitors. In silico docking of selected ligands into the active sites of the respective enzymes has provided useful insight into binding conformations and potential hydrogen-bonding interactions with active-site amino acid residues. A series of furocoumarin carboxamide derivatives have been synthesised in four steps starting from resorcinol and these compounds have also been tested for HIV-1 integrase inhibition activity. The structures of unexpected products isolated from Aza-Baylis-Hillman reactions of N-tosylaldimines have been elucidated by spectroscopic analysis, and confirmed by single crystal X-ray analysis. A mechanism for what appears to be an unprecedented transformation has been proposed. Microwave-assisted SeO₂ oxidation of Baylis-Hillman-derived 3-methylcoumarins has provided convenient and efficient access to coumarin-3-carbaldehydes, and a pilot study has revealed the potential of these coumarin-3-carbaldehydes as scaffolds for the construction of tricyclic compounds. The HCl-catalysed reaction of tert-butyl acrylate derived Baylis-Hillman adducts has been shown to afford 3-(chloromethyl)coumarins and α-(chloromethyl)cinnamic acids, the Zstereochemistry of the latter being established by X-ray crystallography. ¹H NMR-based experimental kinetic and DFT-level theoretical studies have been undertaken to establish the reaction sequence and other mechanistic details. Base-catalysed cyclisation on the other hand, has been shown to afford 2H-chromene rather than coumarin derivatives.
- Full Text:
- Date Issued: 2011
Water supply development decision-making in South Africa
- Authors: Preston, Ian Robert
- Date: 2016
- Subjects: Water security -- South Africa , Water resources development -- South Africa -- Cost effectiveness , Water consumption -- Economic aspects -- South Africa , Water-supply -- South Africa -- Management , Water-supply -- South Africa -- Decision making
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1210 , http://hdl.handle.net/10962/d1020848
- Description: Balancing water demand and supply in South Africa involves high levels of uncertainty. The Department of Water and Sanitation (DWS) is responsible for making decisions to either increase water supply or decrease water demand so as to ensure that sufficient water is available, when and where it is needed. However, no retrospective analyses of such decisions have been found. One way to assess such decisions is to evaluate the associated costs and benefits thereof. Therefore the primary aim of this study is to evaluate the costs and benefits of selected water supply options, and of the decision-making associated with those options. In order to achieve this purpose, four case studies were analysed within a mixed-methods research paradigm, which used both quantitative and qualitative methods, including unit reference value (URV) analysis, inter- and intra-case analysis and content analysis to examine the success of the decisions made. The four case studies were conducted on the Inyaka, Nandoni, Berg and De Hoop dams and their catchments. Firstly, estimated and actual project costs were compared using unit reference analysis and inter-case analyses. Secondly, the reduction of mean annual runoff (MAR) caused by invasive alien plants (IAPs) and the cost of clearing them in the dam catchments were evaluated using inter-case analyses. Information thus gathered was used together with data from DWS documentation and the results of interviews with ten key specialists, to analyse the decision-making process that led to the decision to build De Hoop Dam (the most recent case study). The rational decision-making model (RDMM) was used as a framework within which to analyse and evaluate this decision-making process. This study has also demonstrated how the RDMM can be used to assess decision-making associated with water supply development. The results of this study show that there is considerable variation of estimated costs (at the time that the decision to build the dam was taken) in relation to the actual costs of building the dams and that Ministers were not put in a position to understand the full long-term costs or the opportunity costs of the proposed dams. Furthermore, the most recent IAP data (2008) shows that the impact on water security by IAPs could not offset the water security resulting from building each of the four dams. However, if IAP management is not continued in these catchments, the projected reduction of MAR by IAPs will compromise water security within 45 years. Given the almost exponential spread and densification of IAPs, together with their long-term impact on MAR and increased costs of controlling them, it is clear that IAP management should have been factored into water supply decision-making from the outset. In the analysis of the decision to build the De Hoop Dam, the results show that while the decision-making process that culminated in the decision to build the dam did not follow the steps of the RDMM, DWS appears to have followed a somewhat similar approach. It was found that while there was a need for the provision of additional water in the Olifants catchment, this need was overstated and the resulting overestimation caused the scale and size of the dam to be larger than it could and probably should have been. Additionally, it appears that DWS‘s decision to build the De Hoop Dam themselves, rather than having it built by the private sector, may have been less than optimal. It is recommended that, in future decision-making, DWS needs to incorporate multiple alternative options into the same solution, and to ensure that decision-makers are put into a position to make informed decisions, including adequate consideration of externalities. Furthermore, DWS needs to employ decision-making models such as the RDMM to facilitate retrospective analyses to improve their institutional knowledge. Keywords: water resources management, dams, invasive alien plants, decision-making, unit reference values, rational decision-making model.
- Full Text:
- Date Issued: 2016
- Authors: Preston, Ian Robert
- Date: 2016
- Subjects: Water security -- South Africa , Water resources development -- South Africa -- Cost effectiveness , Water consumption -- Economic aspects -- South Africa , Water-supply -- South Africa -- Management , Water-supply -- South Africa -- Decision making
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1210 , http://hdl.handle.net/10962/d1020848
- Description: Balancing water demand and supply in South Africa involves high levels of uncertainty. The Department of Water and Sanitation (DWS) is responsible for making decisions to either increase water supply or decrease water demand so as to ensure that sufficient water is available, when and where it is needed. However, no retrospective analyses of such decisions have been found. One way to assess such decisions is to evaluate the associated costs and benefits thereof. Therefore the primary aim of this study is to evaluate the costs and benefits of selected water supply options, and of the decision-making associated with those options. In order to achieve this purpose, four case studies were analysed within a mixed-methods research paradigm, which used both quantitative and qualitative methods, including unit reference value (URV) analysis, inter- and intra-case analysis and content analysis to examine the success of the decisions made. The four case studies were conducted on the Inyaka, Nandoni, Berg and De Hoop dams and their catchments. Firstly, estimated and actual project costs were compared using unit reference analysis and inter-case analyses. Secondly, the reduction of mean annual runoff (MAR) caused by invasive alien plants (IAPs) and the cost of clearing them in the dam catchments were evaluated using inter-case analyses. Information thus gathered was used together with data from DWS documentation and the results of interviews with ten key specialists, to analyse the decision-making process that led to the decision to build De Hoop Dam (the most recent case study). The rational decision-making model (RDMM) was used as a framework within which to analyse and evaluate this decision-making process. This study has also demonstrated how the RDMM can be used to assess decision-making associated with water supply development. The results of this study show that there is considerable variation of estimated costs (at the time that the decision to build the dam was taken) in relation to the actual costs of building the dams and that Ministers were not put in a position to understand the full long-term costs or the opportunity costs of the proposed dams. Furthermore, the most recent IAP data (2008) shows that the impact on water security by IAPs could not offset the water security resulting from building each of the four dams. However, if IAP management is not continued in these catchments, the projected reduction of MAR by IAPs will compromise water security within 45 years. Given the almost exponential spread and densification of IAPs, together with their long-term impact on MAR and increased costs of controlling them, it is clear that IAP management should have been factored into water supply decision-making from the outset. In the analysis of the decision to build the De Hoop Dam, the results show that while the decision-making process that culminated in the decision to build the dam did not follow the steps of the RDMM, DWS appears to have followed a somewhat similar approach. It was found that while there was a need for the provision of additional water in the Olifants catchment, this need was overstated and the resulting overestimation caused the scale and size of the dam to be larger than it could and probably should have been. Additionally, it appears that DWS‘s decision to build the De Hoop Dam themselves, rather than having it built by the private sector, may have been less than optimal. It is recommended that, in future decision-making, DWS needs to incorporate multiple alternative options into the same solution, and to ensure that decision-makers are put into a position to make informed decisions, including adequate consideration of externalities. Furthermore, DWS needs to employ decision-making models such as the RDMM to facilitate retrospective analyses to improve their institutional knowledge. Keywords: water resources management, dams, invasive alien plants, decision-making, unit reference values, rational decision-making model.
- Full Text:
- Date Issued: 2016
Effects of Vigna unguiculata and Lablab purpureus on methanogenesis, haematological parameters and the quality of meat from Xhosa Lop Ear goats
- Authors: Washaya, Soul
- Date: 2017
- Subjects: Legumes Forage Forage plants
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/9996 , vital:35249
- Description: The objective of the current study was to evaluate the nutritive value of forage legumes Lablab purpureus (Lablab) and Vigna unguiculata (Cowpea) and their effects on intake, growth, blood parameters and meat quality in Xhosa goats. Forages were established at UFH research farm in the summer of the 2014 /15 growing season in blocks measuring 8m width x 16m long for each legume, replicated three times, making a total of four blocks, and eight treatment units for each legume. Samples were collected at three different stages of growth of preanthesis, anthesis and post anthesis for biomass yield determination. A homogenous sub-sample was then oven dried for 72 hours at 60 0C. After drying the forage samples were milled through a 1mm screen and a 20g sample from each stage of growth and forage sample was subjected to proximate analysis, in-vitro digestibility and anti-nutrient evaluation. The in-vitro digestibility experiment was done with rumen liquor of cattle and sheep collected from an abbatoir. Tannins, total phenolics and sapponins were the only anti-nutrients evaluated as they are perceived to influence methanogenesis in ruminat animals. At 50percent flowering, forage legumes were harvested for hay making which was then used in an in-vivo trial to evaluate the nutritive value of forages. This trial was conducted using eighteen one-year-old goats of average weight 14.2±0.24 kg over a period of sixty days. The results showed that biomass yield, which increased with stage of growth, was significantly higher (P < 0.05) for Lablab than Cowpea (7.968t/ha vs 7.105t/ha). Cowpea exhibited higher moisture content (7.72percent), Ash (13.11percent), acid detergent fibre (ADF) (38.42percent) and crude protein (CP) (20.23percent) than Lablab which had 7.50percent, 11.45 percent, 36.17percent and 19percent, respectively. Lablab forage had significantly higher (P < 0.05) fat content (2.41percent), neutral detergent fibre (NDF) (49.27percent) and hemicellulose (13.07percent) than Cowpea which had 2.1percent; 46.91percent and 8.48percent, respectively. The stage of growth significantly (P < 0.05) affected the mineral content of both forages. Lablab showed significantly higher (P < 0.05) values (1.22percent 0.55percent, 2.67percent) than Cowpea (1.00percent, 0.45percent, 2.30percent) for calcium (Ca), phosphorus (P), and potassium (K) respectively. Lablab forage had significantly higher (P < 0.05) tannin (3.345mgCAE/gDM), phenolic (13.47mgGAE/gDM) and saponin (0.75percent) content compared to Cowpea with values of 1.494mgCAEg/DM; 9.402mgGAE/gDM and vs 1.55percent respectively. The tannin content significantly influenced in-vitro digestibility and enteric methane production. The forage type, harvesting stage and inoculum source significantly (P < 0.05) affected the in-vitro digestibility of the forages. The in-vitro dry matter (IVDM) and in-vitro organic matter (IVOM) digestibility was significantly higher (P < 0.05) for Lablab (41.13percent; 39.63percent) than Cowpea (39.86percent; 19.44percent), respectively. Both forages recorded higher dry matter (DM) digestibility coefficients at anthesis stage of growth 61.58percent, and 51.5 percent for Lablab and Cowpea respectively. The IVOM digestibility increased with stage of harvest (23.7percent to 25.57percent) for Cowpea while Lablab showed a decrease (44.6 percent to 43.9percent) when cattle inoculum was used. The IVDM digestibility was higher (P < 0.05) for Lablab (50.5percent) when cattle inoculum was used while Cowpea was observed to have higher digestibility co-efficiencies (38.54percent) when sheep inoculum was used. Cowpea had lower (P < 0.05) IVOM digestibility than Lablab (19.44percent) vs. 39.6percent). Lablab exhibited higher (P < 0.05) metabolisable energy (ME) values than Cowpea (6.21 vs. 2.70 MJ/kgDM). In the feeding study, the total DM intake by goats for Lablab was higher (P < 0.05) compared to Cowpea (688.1 vs. 607.8 g/head/ day). There was a positive (P < 0.05) correlation between dry matter intake and average daily gain (r= 0.8513, and r=0.5279) for Cowpea and Lablab respectively. Lablab and Cowpea promoted growth of Xhosa goats at a rate of 35.0g/d; and 38.3g/d, respectively which was not significantly different (P > 0.05). However, this growth was associated with a significantly higher (P < 0.05) food conversion ratio (FCR) of 19.16 vs 18.11 for Cowpea and Lablab, respectively. The apparent DM, non structural carbohydrate (NSC) nutrient digestibilities were significantly different (P < 0.05) for Lablab and Cowpea. Furthermore sex of animal influenced significantly (P < 0.05) the DM, ADF, NSC and NDF digestibilities. Lablab and Cowpea did not influence (P > 0.05) individual VFA molar concentrations in both sexes. However, animals fed Lablab had significantly higher butyrate concentrations (P < 0.05). Lablab and Cowpea forages significantly lowered (P > 0.05) enteric methane production in goats compared to a concentrate diet, and this was related to animal activity. Animals produced significantly more (P < 0.05) methane gas when ruminating than feeding or just standing. The average methane produced each year was lower but not significant (P > 0.05) for animals fed Cowpea than Lablab (4.602kg CH4, vs. 4.719kg CH4) when expressed per year. Male animals produced more gas than females with values of 17.40L/day; 12.46 g/kg DMI and 0.126g/day vs. 15.47L/day, 12.28 g/kg DMI, and 0.0109g/day, respectively. Forage legumes had no significant effects (P > 0.05) on serum total proteins (TP), globulin, urea, creatinine, alanine aminotransferase (ALT), alkaline phosphatase (ALP), and gamma- glutamyl transferase (GGT) concentrations, but serum concentration of albumin was influenced by the diets (P < 0.05). Sex of animals significantly influenced ALP concentration (P < 0.05) with male animals exhibiting higer ALP values than females. Measured over time, the plasma concentration of urea and ALP significantly increased (P < 0.05) while creatinine and cholesterol concentration decreased (P < 0.05). Although the overall serum concentration of urea, total proteins, globulin, creatinine, ALT, ALP and GGT remained unchanged among the treatments and between sexes; treatment by sex, treatment by day and sex by day interactions were significant (P < 0.05). The white blood cell (WBC), red blood cell (RBC), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), haemoglobin, haematocrite, platelet and mean platelet volume (MPV) levels were similar among treatments and between sexes (P > 0.05). The WBC decreased with time by 8.07 x10 9/l while mean crepuscular volume (MCV) increased by 11.83(fl) from day 15 to day 55. Treatment diets significantly (P < 0.05) influenced neutrophile (percent) content while sex influenced basophile (percent) content. There were no treatment or sex effects (P > 0.05) on lymphocytes (percent), monocytes (percent) and eosinophiles (percent). In the meat quality study, the dietary treatments and sex had a significant (P < 0.05) effect on dressing out percent (DPpercent), initial pH, redness (a*), yellowness (b*), Warner Blartze Shear force (WBS) , drip loss and cooking loss in the chevon from Xhosa goats. Compared with a commercial pellet diet, Lablab and Cowpea diets resulted in similar slaughter body weights (SBW), hot carcass weight (HCW) and cold dressed mass (CDM) of carcasses. However, female animals exhibited a significantly (P < 0.05) higher DPpercent than male animals (42.3percent vs. 38.9percent) for all treatments. The male animals exhibited significantly (P < 0.05) higher pH values one hour after slaughter than females (5.79 vs 5.67). Neverthreless the diet and gender did not significantly (P > 0.05) affect the ultimate pH (pHu). Meat samples from male animals had significantly (P < 0.05) higher redness values than females. Feeding cowpea significantly (P < 0.05) increased meat redness with the least drip loss of chevon. Female animals produced significantly (P < 0.05) tougher chevon compared to male animals; 4.16kg and 3.36kg for female and male, respectively. Lablab and Cowpea posses high CP levels and moderately lower NDF with high ADF values that influences dry matter intake (DMI), digestibility and growth of goats. These forage legumes meet animal requirements for fat, ADF, NDF, CP, Ca, Mn, zinc and Cu and their biomass yield is satisfactory.
- Full Text:
- Date Issued: 2017
- Authors: Washaya, Soul
- Date: 2017
- Subjects: Legumes Forage Forage plants
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/9996 , vital:35249
- Description: The objective of the current study was to evaluate the nutritive value of forage legumes Lablab purpureus (Lablab) and Vigna unguiculata (Cowpea) and their effects on intake, growth, blood parameters and meat quality in Xhosa goats. Forages were established at UFH research farm in the summer of the 2014 /15 growing season in blocks measuring 8m width x 16m long for each legume, replicated three times, making a total of four blocks, and eight treatment units for each legume. Samples were collected at three different stages of growth of preanthesis, anthesis and post anthesis for biomass yield determination. A homogenous sub-sample was then oven dried for 72 hours at 60 0C. After drying the forage samples were milled through a 1mm screen and a 20g sample from each stage of growth and forage sample was subjected to proximate analysis, in-vitro digestibility and anti-nutrient evaluation. The in-vitro digestibility experiment was done with rumen liquor of cattle and sheep collected from an abbatoir. Tannins, total phenolics and sapponins were the only anti-nutrients evaluated as they are perceived to influence methanogenesis in ruminat animals. At 50percent flowering, forage legumes were harvested for hay making which was then used in an in-vivo trial to evaluate the nutritive value of forages. This trial was conducted using eighteen one-year-old goats of average weight 14.2±0.24 kg over a period of sixty days. The results showed that biomass yield, which increased with stage of growth, was significantly higher (P < 0.05) for Lablab than Cowpea (7.968t/ha vs 7.105t/ha). Cowpea exhibited higher moisture content (7.72percent), Ash (13.11percent), acid detergent fibre (ADF) (38.42percent) and crude protein (CP) (20.23percent) than Lablab which had 7.50percent, 11.45 percent, 36.17percent and 19percent, respectively. Lablab forage had significantly higher (P < 0.05) fat content (2.41percent), neutral detergent fibre (NDF) (49.27percent) and hemicellulose (13.07percent) than Cowpea which had 2.1percent; 46.91percent and 8.48percent, respectively. The stage of growth significantly (P < 0.05) affected the mineral content of both forages. Lablab showed significantly higher (P < 0.05) values (1.22percent 0.55percent, 2.67percent) than Cowpea (1.00percent, 0.45percent, 2.30percent) for calcium (Ca), phosphorus (P), and potassium (K) respectively. Lablab forage had significantly higher (P < 0.05) tannin (3.345mgCAE/gDM), phenolic (13.47mgGAE/gDM) and saponin (0.75percent) content compared to Cowpea with values of 1.494mgCAEg/DM; 9.402mgGAE/gDM and vs 1.55percent respectively. The tannin content significantly influenced in-vitro digestibility and enteric methane production. The forage type, harvesting stage and inoculum source significantly (P < 0.05) affected the in-vitro digestibility of the forages. The in-vitro dry matter (IVDM) and in-vitro organic matter (IVOM) digestibility was significantly higher (P < 0.05) for Lablab (41.13percent; 39.63percent) than Cowpea (39.86percent; 19.44percent), respectively. Both forages recorded higher dry matter (DM) digestibility coefficients at anthesis stage of growth 61.58percent, and 51.5 percent for Lablab and Cowpea respectively. The IVOM digestibility increased with stage of harvest (23.7percent to 25.57percent) for Cowpea while Lablab showed a decrease (44.6 percent to 43.9percent) when cattle inoculum was used. The IVDM digestibility was higher (P < 0.05) for Lablab (50.5percent) when cattle inoculum was used while Cowpea was observed to have higher digestibility co-efficiencies (38.54percent) when sheep inoculum was used. Cowpea had lower (P < 0.05) IVOM digestibility than Lablab (19.44percent) vs. 39.6percent). Lablab exhibited higher (P < 0.05) metabolisable energy (ME) values than Cowpea (6.21 vs. 2.70 MJ/kgDM). In the feeding study, the total DM intake by goats for Lablab was higher (P < 0.05) compared to Cowpea (688.1 vs. 607.8 g/head/ day). There was a positive (P < 0.05) correlation between dry matter intake and average daily gain (r= 0.8513, and r=0.5279) for Cowpea and Lablab respectively. Lablab and Cowpea promoted growth of Xhosa goats at a rate of 35.0g/d; and 38.3g/d, respectively which was not significantly different (P > 0.05). However, this growth was associated with a significantly higher (P < 0.05) food conversion ratio (FCR) of 19.16 vs 18.11 for Cowpea and Lablab, respectively. The apparent DM, non structural carbohydrate (NSC) nutrient digestibilities were significantly different (P < 0.05) for Lablab and Cowpea. Furthermore sex of animal influenced significantly (P < 0.05) the DM, ADF, NSC and NDF digestibilities. Lablab and Cowpea did not influence (P > 0.05) individual VFA molar concentrations in both sexes. However, animals fed Lablab had significantly higher butyrate concentrations (P < 0.05). Lablab and Cowpea forages significantly lowered (P > 0.05) enteric methane production in goats compared to a concentrate diet, and this was related to animal activity. Animals produced significantly more (P < 0.05) methane gas when ruminating than feeding or just standing. The average methane produced each year was lower but not significant (P > 0.05) for animals fed Cowpea than Lablab (4.602kg CH4, vs. 4.719kg CH4) when expressed per year. Male animals produced more gas than females with values of 17.40L/day; 12.46 g/kg DMI and 0.126g/day vs. 15.47L/day, 12.28 g/kg DMI, and 0.0109g/day, respectively. Forage legumes had no significant effects (P > 0.05) on serum total proteins (TP), globulin, urea, creatinine, alanine aminotransferase (ALT), alkaline phosphatase (ALP), and gamma- glutamyl transferase (GGT) concentrations, but serum concentration of albumin was influenced by the diets (P < 0.05). Sex of animals significantly influenced ALP concentration (P < 0.05) with male animals exhibiting higer ALP values than females. Measured over time, the plasma concentration of urea and ALP significantly increased (P < 0.05) while creatinine and cholesterol concentration decreased (P < 0.05). Although the overall serum concentration of urea, total proteins, globulin, creatinine, ALT, ALP and GGT remained unchanged among the treatments and between sexes; treatment by sex, treatment by day and sex by day interactions were significant (P < 0.05). The white blood cell (WBC), red blood cell (RBC), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), haemoglobin, haematocrite, platelet and mean platelet volume (MPV) levels were similar among treatments and between sexes (P > 0.05). The WBC decreased with time by 8.07 x10 9/l while mean crepuscular volume (MCV) increased by 11.83(fl) from day 15 to day 55. Treatment diets significantly (P < 0.05) influenced neutrophile (percent) content while sex influenced basophile (percent) content. There were no treatment or sex effects (P > 0.05) on lymphocytes (percent), monocytes (percent) and eosinophiles (percent). In the meat quality study, the dietary treatments and sex had a significant (P < 0.05) effect on dressing out percent (DPpercent), initial pH, redness (a*), yellowness (b*), Warner Blartze Shear force (WBS) , drip loss and cooking loss in the chevon from Xhosa goats. Compared with a commercial pellet diet, Lablab and Cowpea diets resulted in similar slaughter body weights (SBW), hot carcass weight (HCW) and cold dressed mass (CDM) of carcasses. However, female animals exhibited a significantly (P < 0.05) higher DPpercent than male animals (42.3percent vs. 38.9percent) for all treatments. The male animals exhibited significantly (P < 0.05) higher pH values one hour after slaughter than females (5.79 vs 5.67). Neverthreless the diet and gender did not significantly (P > 0.05) affect the ultimate pH (pHu). Meat samples from male animals had significantly (P < 0.05) higher redness values than females. Feeding cowpea significantly (P < 0.05) increased meat redness with the least drip loss of chevon. Female animals produced significantly (P < 0.05) tougher chevon compared to male animals; 4.16kg and 3.36kg for female and male, respectively. Lablab and Cowpea posses high CP levels and moderately lower NDF with high ADF values that influences dry matter intake (DMI), digestibility and growth of goats. These forage legumes meet animal requirements for fat, ADF, NDF, CP, Ca, Mn, zinc and Cu and their biomass yield is satisfactory.
- Full Text:
- Date Issued: 2017
The use of response surface methodology and artificial neural networks for the establishment of a design space for a sustained release salbutamol sulphate formulation
- Authors: Chaibva, Faith Anesu
- Date: 2010
- Subjects: Salbutamol sulphate Artificial intelligence -- Medical applications Neural networks (Computer science) Response surfaces (Statistics) Pharmaceutical biotechnology -- Quality contro Drugs -- Design Pharmacokinetics Drugs -- Dosage forms Drugs -- Controlled release
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3845 , http://hdl.handle.net/10962/d1010432
- Description: Quality by Design (QbD) is a systematic approach that has been recommended as suitable for the development of quality pharmaceutical products. The QbD approach commences with the definition of a quality target drug profile and predetermined objectives that are then used to direct the formulation development process with an emphasis on understanding the pharmaceutical science and manufacturing principles that apply to a product. The design space is directly linked to the use of QbD for formulation development and is a multidimensional combination and interaction of input variables and process parameters that have been demonstrated to provide an assurance of quality. The objective of these studies was to apply the principles of QbD as a framework for the optimisation of a sustained release (SR) formulation of salbutamol sulphate (SBS), and for the establishment of a design space using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN). SBS is a short-acting ♭₂ agonist that is used for the management of asthma and chronic obstructive pulmonary disease (COPD). The use of a SR formulation of SBS may provide clinical benefits in the management of these respiratory disorders. Ashtalin®8 ER (Cipla Ltd., Mumbai, Maharashtra, India) was selected as a reference formulation for use in these studies. An Ishikawa or Cause and Effect diagram was used to determine the impact of formulation and process factors that have the potential to affect product quality. Key areas of concern that must be monitored include the raw materials, the manufacturing equipment and processes, and the analytical and assessment methods employed. The conditions in the laboratory and manufacturing processes were carefully monitored and recorded for any deviation from protocol, and equipment for assessment of dosage form performance, including dissolution equipment, balances and hardness testers, underwent regular maintenance. Preliminary studies to assess the potential utility of Methocel® Kl OOM, alone and in combination with other matrix forming polymers, revealed that the combination of this polymer with xanthan gum and Carbopol® has the potential to modulate the release of SBS at a specific rate, for a period of 12 hr. A central composite design using Methocel® KlOOM, xanthan gum, Carbopol® 974P and Surelease® as the granulating fluid was constructed to fully evaluate the impact of these formulation variables on the rate and extent of SBS release from manufactured formulations. The results revealed that although Methocel® KlOOM and xanthan gum had the greatest retardant effect on drug release, interactions between the polymers used in the study were also important determinants of the measureable responses. An ANN model was trained for optimisation using the data generated from a central composite study. The efficiency of the network was optimised by assessing the impact of the number of nodes in the hidden layer using a three layer Multi Layer Perceptron (MLP). The results revealed that a network with nine nodes in the hidden layer had the best predictive ability, suitable for application to formulation optimisation studies. Pharmaceutical optimisation was conducted using both the RSM and the trained ANN models. The results from the two optimisation procedures yielded two different formulation compositions that were subjected to in vitro dissolution testing using USP Apparatus 3. The results revealed that, although the formulation compositions that were derived from the optimisation procedures were different, both solutions gave reproducible results for which the dissolution profiles were indeed similar to that of the reference formulation. RSM and ANN were further investigated as possible means of establishing a design space for formulation compositions that would result in dosage forms that have similar in vitro release test profiles comparable to the reference product. Constraint plots were used to determine the bounds of the formulation variables that would result in the manufacture of dosage forms with the desired release profile. ANN simulations with hypothetical formulations that were generated within a small region of the experimental domain were investigated as a means of understanding the impact of varying the composition of the formulation on resultant dissolution profiles. Although both methods were suitable for the establishment of a design space, the use of ANN may be better suited for this purpose because of the manner in which ANN handles data. As more information about the behaviour of a formulation and its processes is generated during the product Iifecycle, ANN may be used to evaluate the impact of formulation and process variables on measureable responses. It is recommended that ANN may be suitable for the optimisation of pharmaceutical formulations and establishment of a design space in line with ICH Pharmaceutical Development [1], Quality Risk Management [2] and Pharmaceutical Quality Systems [3]
- Full Text:
- Date Issued: 2010
- Authors: Chaibva, Faith Anesu
- Date: 2010
- Subjects: Salbutamol sulphate Artificial intelligence -- Medical applications Neural networks (Computer science) Response surfaces (Statistics) Pharmaceutical biotechnology -- Quality contro Drugs -- Design Pharmacokinetics Drugs -- Dosage forms Drugs -- Controlled release
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3845 , http://hdl.handle.net/10962/d1010432
- Description: Quality by Design (QbD) is a systematic approach that has been recommended as suitable for the development of quality pharmaceutical products. The QbD approach commences with the definition of a quality target drug profile and predetermined objectives that are then used to direct the formulation development process with an emphasis on understanding the pharmaceutical science and manufacturing principles that apply to a product. The design space is directly linked to the use of QbD for formulation development and is a multidimensional combination and interaction of input variables and process parameters that have been demonstrated to provide an assurance of quality. The objective of these studies was to apply the principles of QbD as a framework for the optimisation of a sustained release (SR) formulation of salbutamol sulphate (SBS), and for the establishment of a design space using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN). SBS is a short-acting ♭₂ agonist that is used for the management of asthma and chronic obstructive pulmonary disease (COPD). The use of a SR formulation of SBS may provide clinical benefits in the management of these respiratory disorders. Ashtalin®8 ER (Cipla Ltd., Mumbai, Maharashtra, India) was selected as a reference formulation for use in these studies. An Ishikawa or Cause and Effect diagram was used to determine the impact of formulation and process factors that have the potential to affect product quality. Key areas of concern that must be monitored include the raw materials, the manufacturing equipment and processes, and the analytical and assessment methods employed. The conditions in the laboratory and manufacturing processes were carefully monitored and recorded for any deviation from protocol, and equipment for assessment of dosage form performance, including dissolution equipment, balances and hardness testers, underwent regular maintenance. Preliminary studies to assess the potential utility of Methocel® Kl OOM, alone and in combination with other matrix forming polymers, revealed that the combination of this polymer with xanthan gum and Carbopol® has the potential to modulate the release of SBS at a specific rate, for a period of 12 hr. A central composite design using Methocel® KlOOM, xanthan gum, Carbopol® 974P and Surelease® as the granulating fluid was constructed to fully evaluate the impact of these formulation variables on the rate and extent of SBS release from manufactured formulations. The results revealed that although Methocel® KlOOM and xanthan gum had the greatest retardant effect on drug release, interactions between the polymers used in the study were also important determinants of the measureable responses. An ANN model was trained for optimisation using the data generated from a central composite study. The efficiency of the network was optimised by assessing the impact of the number of nodes in the hidden layer using a three layer Multi Layer Perceptron (MLP). The results revealed that a network with nine nodes in the hidden layer had the best predictive ability, suitable for application to formulation optimisation studies. Pharmaceutical optimisation was conducted using both the RSM and the trained ANN models. The results from the two optimisation procedures yielded two different formulation compositions that were subjected to in vitro dissolution testing using USP Apparatus 3. The results revealed that, although the formulation compositions that were derived from the optimisation procedures were different, both solutions gave reproducible results for which the dissolution profiles were indeed similar to that of the reference formulation. RSM and ANN were further investigated as possible means of establishing a design space for formulation compositions that would result in dosage forms that have similar in vitro release test profiles comparable to the reference product. Constraint plots were used to determine the bounds of the formulation variables that would result in the manufacture of dosage forms with the desired release profile. ANN simulations with hypothetical formulations that were generated within a small region of the experimental domain were investigated as a means of understanding the impact of varying the composition of the formulation on resultant dissolution profiles. Although both methods were suitable for the establishment of a design space, the use of ANN may be better suited for this purpose because of the manner in which ANN handles data. As more information about the behaviour of a formulation and its processes is generated during the product Iifecycle, ANN may be used to evaluate the impact of formulation and process variables on measureable responses. It is recommended that ANN may be suitable for the optimisation of pharmaceutical formulations and establishment of a design space in line with ICH Pharmaceutical Development [1], Quality Risk Management [2] and Pharmaceutical Quality Systems [3]
- Full Text:
- Date Issued: 2010
The restoration of an alien-invaded riparian zone in grassy fynbos, South Africa
- Authors: Fourie, Saskia
- Date: 2013
- Subjects: Fynbos ecology -- South Africa Riparian ecology -- South Africa Riparian restoration -- South Africa Alien plants -- South Africa Invasive plants -- South Africa Endemic plants -- South Africa Plants -- Effect of fires on -- South Africa Soil seed banks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4733 , http://hdl.handle.net/10962/d1003840
- Description: The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
- Full Text:
- Date Issued: 2013
- Authors: Fourie, Saskia
- Date: 2013
- Subjects: Fynbos ecology -- South Africa Riparian ecology -- South Africa Riparian restoration -- South Africa Alien plants -- South Africa Invasive plants -- South Africa Endemic plants -- South Africa Plants -- Effect of fires on -- South Africa Soil seed banks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4733 , http://hdl.handle.net/10962/d1003840
- Description: The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
- Full Text:
- Date Issued: 2013
Lending technologies and small, micro and medium enterprise borrowing: evidence from the Eastern Cape province of South
- Authors: Mbedzi, Edson
- Date: 2019
- Subjects: Financial services industry -- Information technology Banks and banking -- Information technology Small business -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Economics)
- Identifier: http://hdl.handle.net/10353/12621 , vital:39293
- Description: Small, Micro and Medium Enterprises (SMMEs) play a major role in contributing to the development of most economies globally. However, such small firms often lack external financing due to their information opacity. Besides, the small firm size nature of most SMMEs impairs their ability to access finance as motivated by the market power theory. In order to address the information asymmetry problem associated with such small firms, financial institutions use different forms of lending technologies as the basis upon which lending decisions are made, that is, whether to loan or not and if the decision to lend is taken, how the intrinsic credit risks are taken into consideration. In the evaluation of the credit worthiness of small businesses, the decision to lend or not depends on soft or hard information acquired through use of a particular lending technology. Many studies in the literature cite access to credit as the main hindrance to SMMEs success. Lending technologies being the conduits transmitting that credit access, the study hypothesises that more emphasis be placed on the relationship between lending technologies and the success of small firms. Success in this case is measured in two ways; the level of SMME credit rationing that small firms endure and the resultant growth of small businesses if they access funding. However, the use of lending technologies as a measure of SMME finance access is missing in academic literature. Specifically, literature on SMMEs in South Africa only narrate the structure of SMMEs and factors affecting SMMEs funding and growth without providing a link on how these eventually influence lending technologies used that determine the lending process. This study therefore traces types of lending technologies used, factors influencing their usage and the subsequent level of credit rationing and growth of small firms. The study uses only formal and registered small firms that are members of the Border-Kei Chamber of Business and Nelson Mandela Bay Business Chamber and listed in their data bases. The study adopts a mixed methods methodology in a two stage analysis approach. In the first stage, the study identifies types of lending technologies used by funding institutions in the study area and factors lenders take into account in order to extend funding to small vi businesses. Based on interview data gathered from eight financial institutions, the types of lending technologies and factors that influence lending decisions are identified using thematic analysis method. In the second stage, the study then interrogates how lending technologies shape the credit rationing and growth of SMMEs within the Eastern Cape Province in South Africa. A sample of three hundred and twenty one (321) randomly selected SMMEs from Buffalo City and Nelson Mandela Bay metropolitans in the Eastern Cape Province is used. Data collected from SMMEs using questionnaires has been analysed to reveal the extent of credit rationing and firm growth variations among SMMEs based on the main lender and firm characteristics identified in the first stage. Credit rationing is both dichotomous, by the firm being either rationed or not, and categorical, by forms of credit rationing experienced by firms. The analysis therefore uses a combination of binary and multinomial logistic regression to evaluate effects of determinants of lending technologies on credit rationing of firms. Financial efficiency scores of firms are used as the proxy for growth of firms. The financial efficiency score is preferred because in its derivation several firm activities are incorporated as opposed to using only one growth indicator such as sales volume. The efficiency scores are generated using Data Enveloping Analysis based on selected main activity inputs and outputs of sampled firms. Since efficiency scores of a firm representing growth are a scale dependent variable, a two-way factorial analysis is used to determine the effect of lender and firm characteristics on the firm’s growth. Both the main and interaction effects of the lender and firm characteristics are captured in the analysis of both credit rationing and growth of firms. Results show that four classes of financial institutions financed formal and registered SMMEs. These are commercial banks, government-owned development financial institutions, private-owned development financial institutions and microfinance institutions. In addition, four types of lending technologies have been used to finance SMMEs in which financial institutions consider people, firm and financial information vii factors as pillars of financing decisions. Findings indicate extensive discriminatory credit rationing among SMMEs in South Africa and that growth paths followed by firms vary significantly as a result of these characteristics. The study therefore recommends the implementation of a financing framework model that allocates funds to different company structures based on credit rationing risk profiles of enterprises so as to minimize the extent of inequality exhibited in the South African population structures which have historical differences on the basis of enterprise size, ownership structure and race. The study further recommends matching of types of lending technologies with types of lenders in order to minimize overall industry credit rationing level in the SMME sector as a supplementary funding model. However, this may need further research to evaluate its application. This is important given that financial institutions use different lending technologies at the same time and further, not all financing institutions may use all forms of lending technologies. For example, microfinance institutions may not have the capacity to use venture capital lending technologies
- Full Text:
- Date Issued: 2019
- Authors: Mbedzi, Edson
- Date: 2019
- Subjects: Financial services industry -- Information technology Banks and banking -- Information technology Small business -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Economics)
- Identifier: http://hdl.handle.net/10353/12621 , vital:39293
- Description: Small, Micro and Medium Enterprises (SMMEs) play a major role in contributing to the development of most economies globally. However, such small firms often lack external financing due to their information opacity. Besides, the small firm size nature of most SMMEs impairs their ability to access finance as motivated by the market power theory. In order to address the information asymmetry problem associated with such small firms, financial institutions use different forms of lending technologies as the basis upon which lending decisions are made, that is, whether to loan or not and if the decision to lend is taken, how the intrinsic credit risks are taken into consideration. In the evaluation of the credit worthiness of small businesses, the decision to lend or not depends on soft or hard information acquired through use of a particular lending technology. Many studies in the literature cite access to credit as the main hindrance to SMMEs success. Lending technologies being the conduits transmitting that credit access, the study hypothesises that more emphasis be placed on the relationship between lending technologies and the success of small firms. Success in this case is measured in two ways; the level of SMME credit rationing that small firms endure and the resultant growth of small businesses if they access funding. However, the use of lending technologies as a measure of SMME finance access is missing in academic literature. Specifically, literature on SMMEs in South Africa only narrate the structure of SMMEs and factors affecting SMMEs funding and growth without providing a link on how these eventually influence lending technologies used that determine the lending process. This study therefore traces types of lending technologies used, factors influencing their usage and the subsequent level of credit rationing and growth of small firms. The study uses only formal and registered small firms that are members of the Border-Kei Chamber of Business and Nelson Mandela Bay Business Chamber and listed in their data bases. The study adopts a mixed methods methodology in a two stage analysis approach. In the first stage, the study identifies types of lending technologies used by funding institutions in the study area and factors lenders take into account in order to extend funding to small vi businesses. Based on interview data gathered from eight financial institutions, the types of lending technologies and factors that influence lending decisions are identified using thematic analysis method. In the second stage, the study then interrogates how lending technologies shape the credit rationing and growth of SMMEs within the Eastern Cape Province in South Africa. A sample of three hundred and twenty one (321) randomly selected SMMEs from Buffalo City and Nelson Mandela Bay metropolitans in the Eastern Cape Province is used. Data collected from SMMEs using questionnaires has been analysed to reveal the extent of credit rationing and firm growth variations among SMMEs based on the main lender and firm characteristics identified in the first stage. Credit rationing is both dichotomous, by the firm being either rationed or not, and categorical, by forms of credit rationing experienced by firms. The analysis therefore uses a combination of binary and multinomial logistic regression to evaluate effects of determinants of lending technologies on credit rationing of firms. Financial efficiency scores of firms are used as the proxy for growth of firms. The financial efficiency score is preferred because in its derivation several firm activities are incorporated as opposed to using only one growth indicator such as sales volume. The efficiency scores are generated using Data Enveloping Analysis based on selected main activity inputs and outputs of sampled firms. Since efficiency scores of a firm representing growth are a scale dependent variable, a two-way factorial analysis is used to determine the effect of lender and firm characteristics on the firm’s growth. Both the main and interaction effects of the lender and firm characteristics are captured in the analysis of both credit rationing and growth of firms. Results show that four classes of financial institutions financed formal and registered SMMEs. These are commercial banks, government-owned development financial institutions, private-owned development financial institutions and microfinance institutions. In addition, four types of lending technologies have been used to finance SMMEs in which financial institutions consider people, firm and financial information vii factors as pillars of financing decisions. Findings indicate extensive discriminatory credit rationing among SMMEs in South Africa and that growth paths followed by firms vary significantly as a result of these characteristics. The study therefore recommends the implementation of a financing framework model that allocates funds to different company structures based on credit rationing risk profiles of enterprises so as to minimize the extent of inequality exhibited in the South African population structures which have historical differences on the basis of enterprise size, ownership structure and race. The study further recommends matching of types of lending technologies with types of lenders in order to minimize overall industry credit rationing level in the SMME sector as a supplementary funding model. However, this may need further research to evaluate its application. This is important given that financial institutions use different lending technologies at the same time and further, not all financing institutions may use all forms of lending technologies. For example, microfinance institutions may not have the capacity to use venture capital lending technologies
- Full Text:
- Date Issued: 2019
Promoting healthy and safe school environments : the role of school governance - a study in the East London and Butterworth educational districts of the Eastern Cape, South Africa
- Authors: Napier, Astrid
- Date: 2018
- Subjects: School children -- Health and hygiene -- South Africa -- Eastern Cape School hygiene -- South Africa Environmental risk assessment -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9489 , vital:34356
- Description: This thesis investigated how school governance promoted healthy and safe school environments and focussed on elements that make the school environment unhealthy and unsafe. These elements were spatial density, sanitation, ventilation, visibility, the acoustic element of the school environment, the aesthetic element and the psychosocial school environment. These are very important elements, and the neglect thereof could lead to ill health. The study excluded elements such as violence and substance use, as well as HIV/ AIDS. The research was conducted at six schools in the Butterworth and East London Educational Districts, as well as the district office in each of these two educational districts of the Eastern Cape. The design was a case study, and a qualitative methodology was used. The sample consisted of members from the school governing bodies, that is, the principal, one other member of the school governing body and a member of the school management team, as well as one official from each educational district, totalling twenty participants. A non-probability, purposive sampling method was used. The instrument was semi-structured interviews and document analyses. The researcher also made use of photographic evidence. Findings indicated that although support services were in place, promoting a healthy and safe school environment was a challenge at all of the schools. Various contributing factors such as the lack of support from the Department of Basic Education (DBE) for schools and district officials, non – implementation of policies, lack of infrastructure, lack of human and other resources, lack of security personnel and vandalism, prohibited the promotion of healthy and safe school environments. It is recommended that the DBE pays urgent attention to these elements that make the school environment unhealthy and unsafe; that the DBE fills the gap that exists between the national, provincial and district offices that hamper the flow of infrastructure and the supply of human and other resources. There is also a need for workshops on policy writing and implementation thereof. A workshop focussing on these elements that make the school environment unhealthy and unsafe would also be beneficial.
- Full Text:
- Date Issued: 2018
- Authors: Napier, Astrid
- Date: 2018
- Subjects: School children -- Health and hygiene -- South Africa -- Eastern Cape School hygiene -- South Africa Environmental risk assessment -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9489 , vital:34356
- Description: This thesis investigated how school governance promoted healthy and safe school environments and focussed on elements that make the school environment unhealthy and unsafe. These elements were spatial density, sanitation, ventilation, visibility, the acoustic element of the school environment, the aesthetic element and the psychosocial school environment. These are very important elements, and the neglect thereof could lead to ill health. The study excluded elements such as violence and substance use, as well as HIV/ AIDS. The research was conducted at six schools in the Butterworth and East London Educational Districts, as well as the district office in each of these two educational districts of the Eastern Cape. The design was a case study, and a qualitative methodology was used. The sample consisted of members from the school governing bodies, that is, the principal, one other member of the school governing body and a member of the school management team, as well as one official from each educational district, totalling twenty participants. A non-probability, purposive sampling method was used. The instrument was semi-structured interviews and document analyses. The researcher also made use of photographic evidence. Findings indicated that although support services were in place, promoting a healthy and safe school environment was a challenge at all of the schools. Various contributing factors such as the lack of support from the Department of Basic Education (DBE) for schools and district officials, non – implementation of policies, lack of infrastructure, lack of human and other resources, lack of security personnel and vandalism, prohibited the promotion of healthy and safe school environments. It is recommended that the DBE pays urgent attention to these elements that make the school environment unhealthy and unsafe; that the DBE fills the gap that exists between the national, provincial and district offices that hamper the flow of infrastructure and the supply of human and other resources. There is also a need for workshops on policy writing and implementation thereof. A workshop focussing on these elements that make the school environment unhealthy and unsafe would also be beneficial.
- Full Text:
- Date Issued: 2018
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