Deterrents to continued blood donation among regular blood donors
- Authors: Harris, Maryke
- Date: 2017
- Subjects: Marketing -- Decision making -- Health aspects -- South Africa Blood donors -- South Africa -- Port Elizabeth , Blood -- Collection and preservation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/15934 , vital:28292
- Description: Collecting blood from repeat blood donors is cost effective and safer compared to other donor types. At the end of 2012, 84% of the SANBS donor panel were inactive or lapsed. There is a lack of research available on lapsed donors in the South African context and available research is mostly quantitative with subtle contradictions. Donors who donated blood in 2012 at fixed site donor centres in Port Elizabeth, and did not return in 2013, were studied. A descriptive analysis was done and a random sample of 78 lapsed donors were selected to participate in a face-to-face interview. Interviews were digitally recorded and transcribed. A grounded model was developed from various existing theories to seek out and conceptualise social patterns and structures of lapsed blood donors through a process of comparison. There were 10 062 donors who donated blood in 2012 and 4 923 became lapsed during 2013. Analysis of sub groups showed a higher proportion of donors who became lapsed in the following sub-categories: new donors (95%), re-joined donors (64%), black donors (63%), donors younger than 40 (61%), female donors (52%). The feedback received from the 11 participants highlighted peer pressure as the biggest motivator. Of the six communication theories applied, The Social Penetration Theory highlighted the cost-minus-benefit ratio which played a big role in a donor’s motivation and decision to return. The AIDA Marketing Model application described lapsed donor behaviour most comprehensively and it highlighted a missing step which was created as part of a Grounded Model and is called the AIDAA Model. The role and existence of peer pressure is directly linked to donor motivation and is categorised as an Action Motivator in the AIDAA Model. The new model creates additional recruitment opportunities which has not been explored and applied strategically before.
- Full Text:
- Date Issued: 2017
- Authors: Harris, Maryke
- Date: 2017
- Subjects: Marketing -- Decision making -- Health aspects -- South Africa Blood donors -- South Africa -- Port Elizabeth , Blood -- Collection and preservation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/15934 , vital:28292
- Description: Collecting blood from repeat blood donors is cost effective and safer compared to other donor types. At the end of 2012, 84% of the SANBS donor panel were inactive or lapsed. There is a lack of research available on lapsed donors in the South African context and available research is mostly quantitative with subtle contradictions. Donors who donated blood in 2012 at fixed site donor centres in Port Elizabeth, and did not return in 2013, were studied. A descriptive analysis was done and a random sample of 78 lapsed donors were selected to participate in a face-to-face interview. Interviews were digitally recorded and transcribed. A grounded model was developed from various existing theories to seek out and conceptualise social patterns and structures of lapsed blood donors through a process of comparison. There were 10 062 donors who donated blood in 2012 and 4 923 became lapsed during 2013. Analysis of sub groups showed a higher proportion of donors who became lapsed in the following sub-categories: new donors (95%), re-joined donors (64%), black donors (63%), donors younger than 40 (61%), female donors (52%). The feedback received from the 11 participants highlighted peer pressure as the biggest motivator. Of the six communication theories applied, The Social Penetration Theory highlighted the cost-minus-benefit ratio which played a big role in a donor’s motivation and decision to return. The AIDA Marketing Model application described lapsed donor behaviour most comprehensively and it highlighted a missing step which was created as part of a Grounded Model and is called the AIDAA Model. The role and existence of peer pressure is directly linked to donor motivation and is categorised as an Action Motivator in the AIDAA Model. The new model creates additional recruitment opportunities which has not been explored and applied strategically before.
- Full Text:
- Date Issued: 2017
Developing academic literacies through understanding the nature of disciplinary knowledge
- Clarence, Sherran, McKenna, Sioux
- Authors: Clarence, Sherran , McKenna, Sioux
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61062 , vital:27942 , https://doi.org/10.18546/LRE.15.1.04
- Description: Much academic development work that is framed by academic literacies, especially that focused on writing, is concerned with disciplinary conventions and knowledges: conceptual, practical, and procedural. This paper argues, however, that academic literacies work tends to conflate literacy practices with disciplinary knowledge structures, thus obscuring the structures from which these practices emanate. This paper demonstrates how theoretical and analytical tools for conceptualizing disciplinary knowledge structures can connect these with academic literacies development work. Using recent studies that combine academic literacies and theories of knowledge in novel ways, this paper will show that understanding the knowledge structures of different disciplines can enable academic developers to build a stronger body of practice. This will enable academic developers working within disciplinary contexts to more ably speak to the nature of coming to know in higher education.
- Full Text:
- Date Issued: 2017
- Authors: Clarence, Sherran , McKenna, Sioux
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61062 , vital:27942 , https://doi.org/10.18546/LRE.15.1.04
- Description: Much academic development work that is framed by academic literacies, especially that focused on writing, is concerned with disciplinary conventions and knowledges: conceptual, practical, and procedural. This paper argues, however, that academic literacies work tends to conflate literacy practices with disciplinary knowledge structures, thus obscuring the structures from which these practices emanate. This paper demonstrates how theoretical and analytical tools for conceptualizing disciplinary knowledge structures can connect these with academic literacies development work. Using recent studies that combine academic literacies and theories of knowledge in novel ways, this paper will show that understanding the knowledge structures of different disciplines can enable academic developers to build a stronger body of practice. This will enable academic developers working within disciplinary contexts to more ably speak to the nature of coming to know in higher education.
- Full Text:
- Date Issued: 2017
Developing end-user requirements for the design of an eProcurement portal
- Authors: Du Preez, Pedro Gordon
- Date: 2017
- Subjects: End-user computing , Government purchasing -- South Africa Business information services Management information systems Business logistics -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/33272 , vital:32628
- Description: During the 2015 South African budget speech, the country was made aware of the proposed changes to be introduced to the tendering process. These changes were to be implemented from 1 April 2015 and were to span over two years. The changes were to facilitate the transition of the tendering process from a paper- based system to a completely digital process, where the majority of the processes will take place on an eProcurement portal (www.etenders.gov.za). This means that businesses will be obligated to use the portal, in order to access tender opportunities and ultimately, to submit tenders on this portal, with the phasing out of all paper-based tender processes. If the portal is to succeed it has to be well adopted by its users. If the portal is not adopted or is used incorrectly, businesses might struggle to access tender opportunities for their business. This research searches to address this problem by helping the users of this portal to gain efficient and effective access to tendering opportunities, through finding and developing user requirements for successful adoption from a user experience perspective. The primary objective of this research is to develop end-user requirements for the design of an eProcurement portal. To achieve this, a general understanding of the legal policies in place for tendering is necessary, as well as a first-hand experience of the users. Case study research methodology and a mixed method approach are used to gather both qualitative and quantitative data. The case study is conducted in the Eastern Cape and directed at business within the construction sector that do tender, as this research is only focusing on the end user and their roles within the tendering process and not on the government internal tendering processes. The outcome of this research is to offer a list of user requirements that can be used within the design of the eProcurement portal that will function as valuable material towards the adoption and effectiveness of the eProcurement portal.
- Full Text:
- Date Issued: 2017
- Authors: Du Preez, Pedro Gordon
- Date: 2017
- Subjects: End-user computing , Government purchasing -- South Africa Business information services Management information systems Business logistics -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/33272 , vital:32628
- Description: During the 2015 South African budget speech, the country was made aware of the proposed changes to be introduced to the tendering process. These changes were to be implemented from 1 April 2015 and were to span over two years. The changes were to facilitate the transition of the tendering process from a paper- based system to a completely digital process, where the majority of the processes will take place on an eProcurement portal (www.etenders.gov.za). This means that businesses will be obligated to use the portal, in order to access tender opportunities and ultimately, to submit tenders on this portal, with the phasing out of all paper-based tender processes. If the portal is to succeed it has to be well adopted by its users. If the portal is not adopted or is used incorrectly, businesses might struggle to access tender opportunities for their business. This research searches to address this problem by helping the users of this portal to gain efficient and effective access to tendering opportunities, through finding and developing user requirements for successful adoption from a user experience perspective. The primary objective of this research is to develop end-user requirements for the design of an eProcurement portal. To achieve this, a general understanding of the legal policies in place for tendering is necessary, as well as a first-hand experience of the users. Case study research methodology and a mixed method approach are used to gather both qualitative and quantitative data. The case study is conducted in the Eastern Cape and directed at business within the construction sector that do tender, as this research is only focusing on the end user and their roles within the tendering process and not on the government internal tendering processes. The outcome of this research is to offer a list of user requirements that can be used within the design of the eProcurement portal that will function as valuable material towards the adoption and effectiveness of the eProcurement portal.
- Full Text:
- Date Issued: 2017
Development and assessment of gastric-retentive sustained release metronidazole microcapsules
- Authors: Makan, Anjana
- Date: 2017
- Subjects: Metronidazole , Drug delivery systems , Helicobacter pylori , High performance liquid chromatography , Gas chromatography , Drugs , Drugs Controlled release
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59240 , vital:27491
- Description: Helicobacter pylori is one of the most common pathogenic bacterial infections and is the leading cause of gastritis, gastroduodenal ulcer disease and gastric cancers. Studies have revealed the prevalence of Helicobacter pylori is high in many countries around the globe. Although Helicobacter pylori is highly sensitive to antimicrobial agents in vitro the clinical eradication rate of the disease is still low. The instability of API at gastric pH, low concentration of API in the gastric mucosa and short gastric residence times are the main reasons for poor eradication rates. The high prevalence rate of this disease necessitates the design and development of gastric-retentive site specific oral dosage forms for the optimized delivery of existing therapeutic molecules and may be an approach to improving the eradication rate of Helicobacter pylori. Metronidazole (MTZ) is a 5-nitroimidazole derivative that exhibits antibiotic and antiprotozoal activity. MTZ is used in combination with other compounds for the treatment of Helicobacter pylori in peptic ulcer disease. MTZ is a potential candidate for inclusion in a sustained release gastric-retentive delivery system that acts in the stomach and since it is unstable in the intestinal/colonic environment enhancing gastric residence time would be a therapeutic advantage. MTZ is a cost-effective therapy that exhibits good anti-microbial activity and has a favourable pharmacokinetic profile. A sustained release gastric-retentive formulation is therefore proposed as an approach to enhance the local delivery of MTZ and improve treatment outcomes for patients infected with Helicobacter pylori. A stability indicating Reversed-Phase High Performance Liquid Chromatography (RP- HPLC) method for the quantitation of MTZ in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The RP-HPLC method was found to be linear, accurate, precise, sensitive, selective, and was applied to the analysis of MTZ in commercially available medicines. Preformulation studies were conducted as preparative work prior to manufacture gastric- retentive sustained release MTZ microcapsules. The experiments conducted were tailored for the development of sustained release MTZ microcapsules using a solvent evaporation method. The particle size and shape of the microcapsules was investigated using Scanning Electron Microscopy (SEM). MTZ- excipient compatibility studies were performed using Fourier Transform Infra-red Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). The results revealed that no definite interaction between MTZ and intended excipients to be used for manufacture of MTZ formulations occurred. A solvent evaporation procedure was used for the manufacture of MTZ microcapsules. Preliminary formulations were manufactured using two different grades of Methocel® at various levels. In addition the impact of processing parameters on performance was also investigated. The formulations were assessed in terms of in vitro release, buoyancy, yield, encapsulation efficiency and microcapsule size. Formulation optimisation was undertaken using a CCD approach and numerical optimisation was used to predict an optimised formulation composition that would produce minimal initial MTZ release, maximum MTZ release at 12 hours and maximum buoyancy, encapsulation efficiency and yield. The kinetics of MTZ release from microcapsules was established by fitting in vitro release data to different mathematical models. Higuchi model and first-order model appeared to best fit the data as majority of the formulation batches had highest R2 values for these models. Short-term stability assessment of the optimised formulation was established by undertaking stability studies at 25°C/60% RH and 40°C/75%RH. No significant changes in any of the CQA were observed over 30 days of stability testing. A gas chromatographic (GC) method was developed and validated for the quantitation of residual acetone and n-hexane. The optimised formulation contained 213.60 ppm/g acetone and 25.23 ppm/g n-hexane which are well below the limits set for residual solvents. In conclusion, gastric-retentive sustained release MTZ microcapsules with potential for further development and optimisation have been successfully developed and assessed in these studies. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2017
- Full Text:
- Date Issued: 2017
- Authors: Makan, Anjana
- Date: 2017
- Subjects: Metronidazole , Drug delivery systems , Helicobacter pylori , High performance liquid chromatography , Gas chromatography , Drugs , Drugs Controlled release
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59240 , vital:27491
- Description: Helicobacter pylori is one of the most common pathogenic bacterial infections and is the leading cause of gastritis, gastroduodenal ulcer disease and gastric cancers. Studies have revealed the prevalence of Helicobacter pylori is high in many countries around the globe. Although Helicobacter pylori is highly sensitive to antimicrobial agents in vitro the clinical eradication rate of the disease is still low. The instability of API at gastric pH, low concentration of API in the gastric mucosa and short gastric residence times are the main reasons for poor eradication rates. The high prevalence rate of this disease necessitates the design and development of gastric-retentive site specific oral dosage forms for the optimized delivery of existing therapeutic molecules and may be an approach to improving the eradication rate of Helicobacter pylori. Metronidazole (MTZ) is a 5-nitroimidazole derivative that exhibits antibiotic and antiprotozoal activity. MTZ is used in combination with other compounds for the treatment of Helicobacter pylori in peptic ulcer disease. MTZ is a potential candidate for inclusion in a sustained release gastric-retentive delivery system that acts in the stomach and since it is unstable in the intestinal/colonic environment enhancing gastric residence time would be a therapeutic advantage. MTZ is a cost-effective therapy that exhibits good anti-microbial activity and has a favourable pharmacokinetic profile. A sustained release gastric-retentive formulation is therefore proposed as an approach to enhance the local delivery of MTZ and improve treatment outcomes for patients infected with Helicobacter pylori. A stability indicating Reversed-Phase High Performance Liquid Chromatography (RP- HPLC) method for the quantitation of MTZ in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The RP-HPLC method was found to be linear, accurate, precise, sensitive, selective, and was applied to the analysis of MTZ in commercially available medicines. Preformulation studies were conducted as preparative work prior to manufacture gastric- retentive sustained release MTZ microcapsules. The experiments conducted were tailored for the development of sustained release MTZ microcapsules using a solvent evaporation method. The particle size and shape of the microcapsules was investigated using Scanning Electron Microscopy (SEM). MTZ- excipient compatibility studies were performed using Fourier Transform Infra-red Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). The results revealed that no definite interaction between MTZ and intended excipients to be used for manufacture of MTZ formulations occurred. A solvent evaporation procedure was used for the manufacture of MTZ microcapsules. Preliminary formulations were manufactured using two different grades of Methocel® at various levels. In addition the impact of processing parameters on performance was also investigated. The formulations were assessed in terms of in vitro release, buoyancy, yield, encapsulation efficiency and microcapsule size. Formulation optimisation was undertaken using a CCD approach and numerical optimisation was used to predict an optimised formulation composition that would produce minimal initial MTZ release, maximum MTZ release at 12 hours and maximum buoyancy, encapsulation efficiency and yield. The kinetics of MTZ release from microcapsules was established by fitting in vitro release data to different mathematical models. Higuchi model and first-order model appeared to best fit the data as majority of the formulation batches had highest R2 values for these models. Short-term stability assessment of the optimised formulation was established by undertaking stability studies at 25°C/60% RH and 40°C/75%RH. No significant changes in any of the CQA were observed over 30 days of stability testing. A gas chromatographic (GC) method was developed and validated for the quantitation of residual acetone and n-hexane. The optimised formulation contained 213.60 ppm/g acetone and 25.23 ppm/g n-hexane which are well below the limits set for residual solvents. In conclusion, gastric-retentive sustained release MTZ microcapsules with potential for further development and optimisation have been successfully developed and assessed in these studies. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2017
- Full Text:
- Date Issued: 2017
Development and assessment of ketoconazole intravaginal thermosetting hydrogel formulations
- Authors: Ramanah, Ashmita
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5198 , vital:20785
- Description: Imidazole compounds are commonly used as antifungal therapies and ketoconazole was the first broad spectrum orally active azole identified and registered. However, the risks of hepatotoxicity and drug interactions following systemic delivery and absorption of ketoconazole outweigh the therapeutic benefits and ketoconazole was therefore discontinued as first line systemic antifungal therapy in many countries. Although not yet banned in South Africa, the South African Medicine Formulary has ceased to recommend the use of ketoconazole for systemic treatment. Topical use of ketoconazole is, however, regarded as safe following extensive human use as low systemic absorption occurs following topical administration. Vulvo-vaginal candidiasis is a yeast infection that affects a large number of women, some of whom present with several infections annually. The topical treatment options for vulvo-vaginal candidiasis include the use of vaginal tablets, capsules, ovules and creams administered as a single dose or one to three times daily for three to fourteen days either alone or in combination with another dosage form depending on the regimen. Administration of the dose nightly is recommended for most vaginal creams and ovule formulation due to leakage and the uncomfortable feel of the dosage form if administered during the day. A thermosetting gel that remains in the vagina following administration and prolongs the release of ketoconazole from a once daily dose would be a useful addition to the arsenal for intra-vaginal antifungal therapy. Thermosetting gels would be more comfortable to administer as the gel would set in a form similar to naturally occurring mucous in the vagina and, if formulated with a low pH, irritation of the sensitive and fissured tissue would be minimised. A further benefit would be that once set the gel would loosely take on the anatomical shape of the vagina. A simple, precise, accurate, reproducible and sensitive stability-indicating reversed phase-high performance liquid chromatographic method using ultraviolet detection for the quantitation of ketoconazole was developed and validated. The method was specific and was applied to the determination of ketoconazole in commercial and experimental formulations in addition to samples from degradation studies and in vitro release testing. Product performance characteristics of commercial products were investigated with the goal to provide a strategy for the development of a novel intra vaginal gel in the shortest possible time. Characterisation of Xolegel®, Kez® shampoo and Ketazol® cream included an evaluation of pH, viscosity and assay, in addition to spectroscopic and thermal analysis, to identify ideal characteristics of topical products that could be used as targets during formulation development of the gel. An in vitro release method was developed and validated for precision and accuracy and the in vitro release profiles of commercial ketoconazole products were compared using analysis of variance, model dependent and independent approaches. Ketoconazole release data from test gel manufactured during formulation development were investigated to obtain information about the relationship between formulation content and drug release. Poloxamers marketed as Pluronic® and Lutrol® are synthetic non-ionic tri-block copolymers that consist of hydrophobic propylene oxide and hydrophilic polyethylene oxide blocks, which in solution interact to exhibit thermo-reversible behaviour. In situ forming hydrogels consisting of poloxamers, more specifically poloxamer 407, are activated following a temperature stimulus and undergo a sol to gel transition. This approach was used to produce a thermosetting vaginal gel that would exhibit a long residence time in the vagina with an associated enhancement of therapeutic efficacy. Ketoconazole- excipient compatibility was investigated during preformulation studies using spectroscopic and thermal analysis to enable the selection of excipients best suited for the production of a novel dosage form prior to formulation development activities. No obvious interactions between ketoconazole and excipient were observed and ketoconazole was found in an amorphous form when in combination with polysorbate 80 and poloxamers. A two-level factorial design was used to produce solvent systems with different amounts of polysorbate 80, citric acid and ethanol to identify a vehicle in which ketoconazole exhibited optimum solubility and at a pH that would be least irritating to the vaginal mucosa with a low content of excipients. The optimised vehicle consisted of 4% m/v citric acid, 1.5% v/v polysorbate 80 and 9.5% v/v ethanol made up to 50 g with citrate-phosphate buffer adjusted to pH 5.0, resulted in a vehicle of pH of 3.5 in which 71.41 mg of ketoconazole was dissolved per mL. A Central Composite Design was used to evaluate compositions for the modulation of viscosity of the thermosetting dosage form such that it was a liquid at 22 °C that rapidly formed a stiff gel when heated to 37 °C (intra-vaginal temperature) using different amounts of the poloxamer grades 407, 188 and 237. Thermosetting gels containing 2% m/v ketoconazole were manufactured using specifications generated using the Central Composite Design and the viscosity at 22 °C and 37 °C, solution to gel transition time, potency and ketoconazole release at 24, 48 and 72 hours investigated. Contour and three-dimensional response surface plots and mathematical relationships with target ranges set for responses were identified and with the aid of Central Composite Design the optimisation of a desirable thermosetting gel was achieved. The optimised composition included 16% m/v poloxamer 407, 10% m/v poloxamer 188 and 6% m/v poloxamer 237 in the gel that was used as the basis for further optimisation studies. The low ketoconazole release for ketoconazole observed indicated that the poloxamers had formed a gel matrix that sustained the release of ketoconazole and would therefore ensure that once daily administration of the gel was possible. The sol-gel transition test may be used as a simple and cheap alternative to viscosity testing for thermosetting formulations when expensive viscometers and rheometers are unavailable and was successfully used for this purpose.Ketoconazole is photolabile and is prone to degradation in aqueous solutions. The hydrophobic core of micelles formed in these dosage forms are believed to shield ketoconazole molecules and improve stability in aqueous solutions and acidic gels. The thermosetting gel optimised for poloxamer content was subjected to a further Central Composite Design in which sodium metabisulphite content and vehicle pH were investigated. The length of storage was used as a numeric variable and storage condition as a categoric variable at two levels to monitor the stability of the gels. The formulations were investigated at sample times of 0, 1, 2, 4 and 8 weeks at 5 °C, 25 °C and 40 °C. The use of a Central Composite Design facilitated an understanding of the interactions between input variables and their impact on the responses analysed including ketoconazole content, release at 24, 48 and 72 hours, gel pH and viscosity at 22 °C and 37 °C. Design of Experiments may be used as a rapid cost effective tool for an overall assessment of the stability of novel topical dosage forms. However, a more thorough assessment of stability may be required for product registration. Ketoconazole was found to be unstable in the acidic thermosetting gels despite the addition of antioxidant. The gels in liquid form at 5 °C and 25 °C have a low number of micelles for ketoconazole incorporation and therefore additional optimisation studies would be required to enhance the shelf-life of this product.
- Full Text:
- Date Issued: 2017
- Authors: Ramanah, Ashmita
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5198 , vital:20785
- Description: Imidazole compounds are commonly used as antifungal therapies and ketoconazole was the first broad spectrum orally active azole identified and registered. However, the risks of hepatotoxicity and drug interactions following systemic delivery and absorption of ketoconazole outweigh the therapeutic benefits and ketoconazole was therefore discontinued as first line systemic antifungal therapy in many countries. Although not yet banned in South Africa, the South African Medicine Formulary has ceased to recommend the use of ketoconazole for systemic treatment. Topical use of ketoconazole is, however, regarded as safe following extensive human use as low systemic absorption occurs following topical administration. Vulvo-vaginal candidiasis is a yeast infection that affects a large number of women, some of whom present with several infections annually. The topical treatment options for vulvo-vaginal candidiasis include the use of vaginal tablets, capsules, ovules and creams administered as a single dose or one to three times daily for three to fourteen days either alone or in combination with another dosage form depending on the regimen. Administration of the dose nightly is recommended for most vaginal creams and ovule formulation due to leakage and the uncomfortable feel of the dosage form if administered during the day. A thermosetting gel that remains in the vagina following administration and prolongs the release of ketoconazole from a once daily dose would be a useful addition to the arsenal for intra-vaginal antifungal therapy. Thermosetting gels would be more comfortable to administer as the gel would set in a form similar to naturally occurring mucous in the vagina and, if formulated with a low pH, irritation of the sensitive and fissured tissue would be minimised. A further benefit would be that once set the gel would loosely take on the anatomical shape of the vagina. A simple, precise, accurate, reproducible and sensitive stability-indicating reversed phase-high performance liquid chromatographic method using ultraviolet detection for the quantitation of ketoconazole was developed and validated. The method was specific and was applied to the determination of ketoconazole in commercial and experimental formulations in addition to samples from degradation studies and in vitro release testing. Product performance characteristics of commercial products were investigated with the goal to provide a strategy for the development of a novel intra vaginal gel in the shortest possible time. Characterisation of Xolegel®, Kez® shampoo and Ketazol® cream included an evaluation of pH, viscosity and assay, in addition to spectroscopic and thermal analysis, to identify ideal characteristics of topical products that could be used as targets during formulation development of the gel. An in vitro release method was developed and validated for precision and accuracy and the in vitro release profiles of commercial ketoconazole products were compared using analysis of variance, model dependent and independent approaches. Ketoconazole release data from test gel manufactured during formulation development were investigated to obtain information about the relationship between formulation content and drug release. Poloxamers marketed as Pluronic® and Lutrol® are synthetic non-ionic tri-block copolymers that consist of hydrophobic propylene oxide and hydrophilic polyethylene oxide blocks, which in solution interact to exhibit thermo-reversible behaviour. In situ forming hydrogels consisting of poloxamers, more specifically poloxamer 407, are activated following a temperature stimulus and undergo a sol to gel transition. This approach was used to produce a thermosetting vaginal gel that would exhibit a long residence time in the vagina with an associated enhancement of therapeutic efficacy. Ketoconazole- excipient compatibility was investigated during preformulation studies using spectroscopic and thermal analysis to enable the selection of excipients best suited for the production of a novel dosage form prior to formulation development activities. No obvious interactions between ketoconazole and excipient were observed and ketoconazole was found in an amorphous form when in combination with polysorbate 80 and poloxamers. A two-level factorial design was used to produce solvent systems with different amounts of polysorbate 80, citric acid and ethanol to identify a vehicle in which ketoconazole exhibited optimum solubility and at a pH that would be least irritating to the vaginal mucosa with a low content of excipients. The optimised vehicle consisted of 4% m/v citric acid, 1.5% v/v polysorbate 80 and 9.5% v/v ethanol made up to 50 g with citrate-phosphate buffer adjusted to pH 5.0, resulted in a vehicle of pH of 3.5 in which 71.41 mg of ketoconazole was dissolved per mL. A Central Composite Design was used to evaluate compositions for the modulation of viscosity of the thermosetting dosage form such that it was a liquid at 22 °C that rapidly formed a stiff gel when heated to 37 °C (intra-vaginal temperature) using different amounts of the poloxamer grades 407, 188 and 237. Thermosetting gels containing 2% m/v ketoconazole were manufactured using specifications generated using the Central Composite Design and the viscosity at 22 °C and 37 °C, solution to gel transition time, potency and ketoconazole release at 24, 48 and 72 hours investigated. Contour and three-dimensional response surface plots and mathematical relationships with target ranges set for responses were identified and with the aid of Central Composite Design the optimisation of a desirable thermosetting gel was achieved. The optimised composition included 16% m/v poloxamer 407, 10% m/v poloxamer 188 and 6% m/v poloxamer 237 in the gel that was used as the basis for further optimisation studies. The low ketoconazole release for ketoconazole observed indicated that the poloxamers had formed a gel matrix that sustained the release of ketoconazole and would therefore ensure that once daily administration of the gel was possible. The sol-gel transition test may be used as a simple and cheap alternative to viscosity testing for thermosetting formulations when expensive viscometers and rheometers are unavailable and was successfully used for this purpose.Ketoconazole is photolabile and is prone to degradation in aqueous solutions. The hydrophobic core of micelles formed in these dosage forms are believed to shield ketoconazole molecules and improve stability in aqueous solutions and acidic gels. The thermosetting gel optimised for poloxamer content was subjected to a further Central Composite Design in which sodium metabisulphite content and vehicle pH were investigated. The length of storage was used as a numeric variable and storage condition as a categoric variable at two levels to monitor the stability of the gels. The formulations were investigated at sample times of 0, 1, 2, 4 and 8 weeks at 5 °C, 25 °C and 40 °C. The use of a Central Composite Design facilitated an understanding of the interactions between input variables and their impact on the responses analysed including ketoconazole content, release at 24, 48 and 72 hours, gel pH and viscosity at 22 °C and 37 °C. Design of Experiments may be used as a rapid cost effective tool for an overall assessment of the stability of novel topical dosage forms. However, a more thorough assessment of stability may be required for product registration. Ketoconazole was found to be unstable in the acidic thermosetting gels despite the addition of antioxidant. The gels in liquid form at 5 °C and 25 °C have a low number of micelles for ketoconazole incorporation and therefore additional optimisation studies would be required to enhance the shelf-life of this product.
- Full Text:
- Date Issued: 2017
Development and implementation of health promotion activities for the prevention of adolescent pregnancies
- Authors: Chemuru, Nomsa Rutendo
- Date: 2017
- Subjects: Teenage pregnancy -- South Africa -- Makhanda , Teenage pregnancy -- Prevention -- South Africa -- Makhanda
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/5115 , vital:20776
- Description: Of the eight Millennium Development Goals (MDGs) established in 2000 by the World Health Organisation, Millennium Development Goals 5 aimed at improving maternal health by addressing the high maternal mortality rate and increasing universal access to reproductive health by 2015.Adolescent pregnancy contributes to maternal, perinatal and infant mortality and also worsens the empowerment of young girls by negatively affecting their physical, educational, social, and economic development.This is a pressing public health concern in South Africa. The reduction of adolescent pregnancy is vital for achieving the sustainable human, health social and economic development of society at large. Culturally sensitive interventions to prevent adolescent pregnancies not only integrate the communities' norms, values, practices and behavioural patterns into the intervention's design and implementation but also the historical, social and economic contexts in which they exist. Progress has been made on the research on health promotion and education in South Africa; however communities are often not consulted on the design and conduct of health promotion research projects.The aim of the study was to develop and implement culturally sensitive and appropriate health promotion activities for the prevention of adolescent pregnancy in Grahamstown, Glenmore and Ndwayana communities in the Eastern Cape, South Africa.Two community based organisations and community care workers associated with them participated in this Community Based Participatory Research using the PEN-3 cultural model. The first phase of this study involved semi-structured interviews carried out with 14 community care workers to identify factors and consequences of adolescent pregnancies in their respective communities. The audio-recorded interviews were transcribed and coded using NVivo® 2010 software. The PEN 3 cultural model was adopted in the studyto address the socio-cultural factors contributing to adolescent pregnancy in the communities. The second phase involved a series of interactive workshops with CCWs for a participatory development of the facilitator's manual. Responses from CCWs informed the design of this study's intervention strategies. A facilitator's manual was developed to implement health promotion intervention, leading to the third phase of this study. The guided implementationof the health promotion intervention for the prevention of adolescent pregnancy was carried out over a period of 14 months and evaluated in the final phase of the study. The facilitator's manual was modified based on feedback fromCCWs, on possible improvements and cultural appropriateness. Readability testing guided the final modification of the manual. According to the community care workers, there were a number of adolescents who fell pregnant in their communities each year. The CCWs identified the influence of family members, friends and other stakeholders as contributory factors to adolescent pregnancy. They identified the lack of parental support in informing and educating adolescents about sexual health. Adolescents themselves lacked the maturity to recognise the risks and consequences of adolescent pregnancy. The negative perceptions of contraception in the community were discouraging contraceptive use amongst the adolescents. However, the results showed that enablers such as home and school visits done by the community care workers can be utilised to prevent adolescent pregnancy. Other factors included lack of health promotion materials and activities with information about preventing of adolescent pregnancy, and if available, the material is in English, that the adolescents may not comprehend. Socio-economic factors such as poverty, the Child Support Grant, cross generational relationships and coerced sex further contributed to adolescent pregnancy in the communities.CCWs identified the need for a more comprehensive health promotion intervention to prevent of adolescent pregnancy. A facilitator's manual addressing the prevention of adolescent pregnancy was developed and modified through a series participatory workshops with the community care workers.The facilitator's manual was used by CCWs to conducthealth promotion activities encouraging the prevention of adolescent pregnancies within the community's clinics, schools and during home visits. Community based participatory research methods and the PEN-3cultural model were used to develop this culturally sensitive and community specific adolescent pregnancy intervention for and by the CCWs. The participatory development of the facilitator's manual and the regular interactive workshops with the CCWs were strengthened by embedding this project into the development programs of the two non-governmental organisations contributing to sustainable development programs for women and children.
- Full Text:
- Date Issued: 2017
- Authors: Chemuru, Nomsa Rutendo
- Date: 2017
- Subjects: Teenage pregnancy -- South Africa -- Makhanda , Teenage pregnancy -- Prevention -- South Africa -- Makhanda
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/5115 , vital:20776
- Description: Of the eight Millennium Development Goals (MDGs) established in 2000 by the World Health Organisation, Millennium Development Goals 5 aimed at improving maternal health by addressing the high maternal mortality rate and increasing universal access to reproductive health by 2015.Adolescent pregnancy contributes to maternal, perinatal and infant mortality and also worsens the empowerment of young girls by negatively affecting their physical, educational, social, and economic development.This is a pressing public health concern in South Africa. The reduction of adolescent pregnancy is vital for achieving the sustainable human, health social and economic development of society at large. Culturally sensitive interventions to prevent adolescent pregnancies not only integrate the communities' norms, values, practices and behavioural patterns into the intervention's design and implementation but also the historical, social and economic contexts in which they exist. Progress has been made on the research on health promotion and education in South Africa; however communities are often not consulted on the design and conduct of health promotion research projects.The aim of the study was to develop and implement culturally sensitive and appropriate health promotion activities for the prevention of adolescent pregnancy in Grahamstown, Glenmore and Ndwayana communities in the Eastern Cape, South Africa.Two community based organisations and community care workers associated with them participated in this Community Based Participatory Research using the PEN-3 cultural model. The first phase of this study involved semi-structured interviews carried out with 14 community care workers to identify factors and consequences of adolescent pregnancies in their respective communities. The audio-recorded interviews were transcribed and coded using NVivo® 2010 software. The PEN 3 cultural model was adopted in the studyto address the socio-cultural factors contributing to adolescent pregnancy in the communities. The second phase involved a series of interactive workshops with CCWs for a participatory development of the facilitator's manual. Responses from CCWs informed the design of this study's intervention strategies. A facilitator's manual was developed to implement health promotion intervention, leading to the third phase of this study. The guided implementationof the health promotion intervention for the prevention of adolescent pregnancy was carried out over a period of 14 months and evaluated in the final phase of the study. The facilitator's manual was modified based on feedback fromCCWs, on possible improvements and cultural appropriateness. Readability testing guided the final modification of the manual. According to the community care workers, there were a number of adolescents who fell pregnant in their communities each year. The CCWs identified the influence of family members, friends and other stakeholders as contributory factors to adolescent pregnancy. They identified the lack of parental support in informing and educating adolescents about sexual health. Adolescents themselves lacked the maturity to recognise the risks and consequences of adolescent pregnancy. The negative perceptions of contraception in the community were discouraging contraceptive use amongst the adolescents. However, the results showed that enablers such as home and school visits done by the community care workers can be utilised to prevent adolescent pregnancy. Other factors included lack of health promotion materials and activities with information about preventing of adolescent pregnancy, and if available, the material is in English, that the adolescents may not comprehend. Socio-economic factors such as poverty, the Child Support Grant, cross generational relationships and coerced sex further contributed to adolescent pregnancy in the communities.CCWs identified the need for a more comprehensive health promotion intervention to prevent of adolescent pregnancy. A facilitator's manual addressing the prevention of adolescent pregnancy was developed and modified through a series participatory workshops with the community care workers.The facilitator's manual was used by CCWs to conducthealth promotion activities encouraging the prevention of adolescent pregnancies within the community's clinics, schools and during home visits. Community based participatory research methods and the PEN-3cultural model were used to develop this culturally sensitive and community specific adolescent pregnancy intervention for and by the CCWs. The participatory development of the facilitator's manual and the regular interactive workshops with the CCWs were strengthened by embedding this project into the development programs of the two non-governmental organisations contributing to sustainable development programs for women and children.
- Full Text:
- Date Issued: 2017
Development and validation of an In Vitro Release Test (IVRT) to investigate the release of miconazole nitrate from topical cream formulations
- Authors: Purazi, Potiwa
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65223 , vital:28711
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
- Authors: Purazi, Potiwa
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65223 , vital:28711
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
Development and validation of DNA barcoding for biodiversity assessment and conservation of red algae in the Algoa Bay region
- Authors: Mshiywa, Faith Masilive
- Date: 2017
- Subjects: Red algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9011 , vital:34182
- Description: DNA barcoding is a molecular technique that uses a short DNA sequence for species identification. It harnesses global community efforts to establish large-scale public reference libraries to allow species identification. Red algae are a complex group of species and are difficult to identify on morphological grounds only. Red algae have the highest production of halogenated compounds, and are used in the medical and pharmaceutical industries. This study therefore aimed at developing DNA barcodes, universal primers and a Kenton-on-Sea red algae species list, which will aid as a baseline for red algae biodiversity and conservation research. A potential DNA barcode region was designed from the rbcL gene, because rbcL is easy to amplify, easy to sequence and it can differentiate organisms to species level. Primers were designed from multiple red algae rbcL sequences and they were evaluated using bioinformatics tools. Red algae from the Algoa Bay region were screened with these primers and a 77% PCR amplification success was obtained. The PCR products were sequenced and 96% of the amplicons were successfully sequenced and resulted in a barcode sequence length above 700bp, which could be used to identify red algae species. Twenty-six (26) red algae species from Kenton-on-Sea, near Algoa Bay, were successfully identified using the Barcode sequence amplified from a primer set developed from the rbcL gene and were uploaded on the BOLD database for public access. This barcode is, therefore, suitable for use by the South African National Biodiversity Institute or other marine researchers, to identify South African red algae species and ensure the maintenance of their biodiversity and conservation.
- Full Text:
- Date Issued: 2017
- Authors: Mshiywa, Faith Masilive
- Date: 2017
- Subjects: Red algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9011 , vital:34182
- Description: DNA barcoding is a molecular technique that uses a short DNA sequence for species identification. It harnesses global community efforts to establish large-scale public reference libraries to allow species identification. Red algae are a complex group of species and are difficult to identify on morphological grounds only. Red algae have the highest production of halogenated compounds, and are used in the medical and pharmaceutical industries. This study therefore aimed at developing DNA barcodes, universal primers and a Kenton-on-Sea red algae species list, which will aid as a baseline for red algae biodiversity and conservation research. A potential DNA barcode region was designed from the rbcL gene, because rbcL is easy to amplify, easy to sequence and it can differentiate organisms to species level. Primers were designed from multiple red algae rbcL sequences and they were evaluated using bioinformatics tools. Red algae from the Algoa Bay region were screened with these primers and a 77% PCR amplification success was obtained. The PCR products were sequenced and 96% of the amplicons were successfully sequenced and resulted in a barcode sequence length above 700bp, which could be used to identify red algae species. Twenty-six (26) red algae species from Kenton-on-Sea, near Algoa Bay, were successfully identified using the Barcode sequence amplified from a primer set developed from the rbcL gene and were uploaded on the BOLD database for public access. This barcode is, therefore, suitable for use by the South African National Biodiversity Institute or other marine researchers, to identify South African red algae species and ensure the maintenance of their biodiversity and conservation.
- Full Text:
- Date Issued: 2017
Development communication for water conservation in rural and peri-urban communities : a study of three district municipalities in Eastern Cape, South Africa
- Onyenankeya, Kevin Uwaecheghi
- Authors: Onyenankeya, Kevin Uwaecheghi
- Date: 2017
- Subjects: Communication in rural development -- South Africa -- Eastern Cape Water conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8397 , vital:32562
- Description: South Africa continues to ramp up public campaigns to rein in escalating water demand amid dwindling and erratic supply. One of the objectives of the campaign is to reduce water demand in urban areas to 15 precent by 2030 through water conservation and water demand management strategies. While the water conservation drive continue to gain traction among commercial and urban water users, it does not appear to resonate with rural and peri-urban residents. Using the pragmatic convergent parallel mixed methods approach consisting of the quantitative and qualitative methods such as survey, focus groups, and indepth-interviews and observation, this study explored the water conservation attitudes, behaviour and intentions of rural and peri-urban respondents in four Eastern Cape communities in South Africa, and to determine if any factors influence their attitudes and behaviour. The study also attempted to determine whether a dialogic approach to communication about water conservation is likely to lead to positive change in attitude and behaviour. The questionnaires were distributed personally by researcher and trained assistants but respondents were left to complete the questionnaires at their convenience and in their own pace but within a negotiated period of five working days. The collected data were analysed using both parametric and non-parametric methods. The nonparametric methods used include thematic analysis. Transcripts of focus group and individual interviews were coded using Nvivo, while quantitative data was analysed in SPSS and presented in simple frequency and cross tabulation. Regression analysis was used to establish the influence of attitude, subjective norm and perceived behavioural control on water conservation intention. Results revealed respondents consider water conservation important and are favourably disposed to conserving water. Although peri-urban and rural residents considered water important and would want to make effort to conserve water in the future, not all considered water conservation an overarching social priority and, as a result, are generally passive or indifferent to water conservation. The indifference appears to be underpinned by residents’ beliefs about water. Further analysis showed that peri-urban residents have stronger positive attitude towards water conservation and greater intent and commitment towards water conservation than their rural counterpart. Attitude, subjective norm and behavioural control emerged as significant factors influencing water conservation intentions of respondents. The findings suggest that water curtailment behaviours were the prevalent water conservation activities rural and peri-urban residents engaged in, while water efficiency behaviours was very poor among the population. Factors such as cost, need, knowledge and locus of control had significant influence on residents’ water conservation behaviour and intentions, especially in purchasing or installing water efficient appliances. The study found no significant relationship between sociodemographic such as age, level of education and home tenure on resident’s water conservation behaviour or intentions. The findings indicate that many rural and peri-urban communities do not have adequate information on water conservation, what to do, how to do it and why it should be done and this affects their water conservation behaviour. It was also found that engaging residents through participatory dialogue is effective in raising awareness and stimulating interest in water saving activities. The study concludes that rural and peri-urban residents are yet to develop a social ethic of water conservation. The study highlights the need for concerted education and awareness campaign around water issues so as to build community knowledge and support for water conservation. But to encourage residents to make adjustment in deep-rooted “beliefs, habits, or practices” and change to a sustainable water use behaviour in the face of scarce water supplies and increasing demand, requires not just communication to inform and persuade, but also development communication to foster mutual understanding and collective action.
- Full Text:
- Date Issued: 2017
- Authors: Onyenankeya, Kevin Uwaecheghi
- Date: 2017
- Subjects: Communication in rural development -- South Africa -- Eastern Cape Water conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8397 , vital:32562
- Description: South Africa continues to ramp up public campaigns to rein in escalating water demand amid dwindling and erratic supply. One of the objectives of the campaign is to reduce water demand in urban areas to 15 precent by 2030 through water conservation and water demand management strategies. While the water conservation drive continue to gain traction among commercial and urban water users, it does not appear to resonate with rural and peri-urban residents. Using the pragmatic convergent parallel mixed methods approach consisting of the quantitative and qualitative methods such as survey, focus groups, and indepth-interviews and observation, this study explored the water conservation attitudes, behaviour and intentions of rural and peri-urban respondents in four Eastern Cape communities in South Africa, and to determine if any factors influence their attitudes and behaviour. The study also attempted to determine whether a dialogic approach to communication about water conservation is likely to lead to positive change in attitude and behaviour. The questionnaires were distributed personally by researcher and trained assistants but respondents were left to complete the questionnaires at their convenience and in their own pace but within a negotiated period of five working days. The collected data were analysed using both parametric and non-parametric methods. The nonparametric methods used include thematic analysis. Transcripts of focus group and individual interviews were coded using Nvivo, while quantitative data was analysed in SPSS and presented in simple frequency and cross tabulation. Regression analysis was used to establish the influence of attitude, subjective norm and perceived behavioural control on water conservation intention. Results revealed respondents consider water conservation important and are favourably disposed to conserving water. Although peri-urban and rural residents considered water important and would want to make effort to conserve water in the future, not all considered water conservation an overarching social priority and, as a result, are generally passive or indifferent to water conservation. The indifference appears to be underpinned by residents’ beliefs about water. Further analysis showed that peri-urban residents have stronger positive attitude towards water conservation and greater intent and commitment towards water conservation than their rural counterpart. Attitude, subjective norm and behavioural control emerged as significant factors influencing water conservation intentions of respondents. The findings suggest that water curtailment behaviours were the prevalent water conservation activities rural and peri-urban residents engaged in, while water efficiency behaviours was very poor among the population. Factors such as cost, need, knowledge and locus of control had significant influence on residents’ water conservation behaviour and intentions, especially in purchasing or installing water efficient appliances. The study found no significant relationship between sociodemographic such as age, level of education and home tenure on resident’s water conservation behaviour or intentions. The findings indicate that many rural and peri-urban communities do not have adequate information on water conservation, what to do, how to do it and why it should be done and this affects their water conservation behaviour. It was also found that engaging residents through participatory dialogue is effective in raising awareness and stimulating interest in water saving activities. The study concludes that rural and peri-urban residents are yet to develop a social ethic of water conservation. The study highlights the need for concerted education and awareness campaign around water issues so as to build community knowledge and support for water conservation. But to encourage residents to make adjustment in deep-rooted “beliefs, habits, or practices” and change to a sustainable water use behaviour in the face of scarce water supplies and increasing demand, requires not just communication to inform and persuade, but also development communication to foster mutual understanding and collective action.
- Full Text:
- Date Issued: 2017
Development of a liposomal acyclovir mucoadhesive film
- Authors: Nalungwe, Sarah
- Date: 2017
- Subjects: Clinical pharmacology , Liposomes Nanomedicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14212 , vital:27451
- Description: Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The efficacy of oral acyclovir is limited as a result of its low bioavailability (15-30%) as it is poorly water soluble and therefore requires a frequent dosing regimen. When orally administered, peak plasma concentration occurs after 1.5–2.5 hours, while its elimination half-life is approximately 2-3 hours. Acyclovir displays poor solubility in water and in lipid bilayers, which leads to poor drug levels at target sites after oral, local, or parenteral administration. In order to improve this lack of solubility, novel amphiphilic derivatives have been designed to form nanoparticles, which allow for the efficient encapsulation of this hydrophobic antiviral agent. Reformulation of drugs in liposomes has provided an opportunity to enhance the therapeutic indices of various agents mainly via alteration of their bio-distribution. Liposomal drug delivery systems have received considerable attention due to their immense advantages which include, effective encapsulation of both small and large molecules that have a wide range of hydrophobicity levels and pKa values, prolonging and targeting release of therapeutic agents by modification of liposomal surface and also minimising clinical drug dose thus reducing toxicity effects. Liposomes exhibit a number of special biological characteristics, including specific interactions with biological membranes and various cells, hence, liposomes are used as biocompatible carriers to improve delivery properties across mucus membranes. Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for improved therapeutic outcome. The aim of this study was to develop an acyclovir liposomal mucoadhesive film by actively encapsulating acyclovir into liposomes and preparing a mucoadhesive film to optimise delivery of acyclovir liposomes at target sites. To actively encapsulate acyclovir and prepare the acyclovir-containing liposomes, a comprehensive statistical methodology was used in optimising the liposome formulation to encapsulate acyclovir. Central composite design was used as the response surface methodology statistical tool to design and develop an optimised method for active encapsulation of acyclovir into liposomes. The predicted optimised encapsulation parameters were incubation temperature of 60 °C and incubation time of 45 minutes. The mean percentage encapsulation calculated was 27.72%. The overall average size of the liposomes was 99.5 nm with a narrow distribution polydispersity index of 0.105 and were physically characterised as small unilamellar vesicles which possessed an average zeta potential of -45.6 mV. High Performance Liquid Chromatography (HPLC) was used to analyse and determine acyclovir drug content in the liposomes and drug release pattern from the mucoadhesive film. Polyvinyl-pyrrolidone (PVP) and Polyethylene glycol (PEG) were used in the preparation of mucoadhesive film, in which the acyclovir encapsulated liposomes were incorporated. The average amount of acyclovir drug content quantified to be in 4 cm2 of the mucoadhesive film was 36.8543 μg. The average tensile strength of the mucoadhesive film was determined to be 3.06 N/mm2 with an elongation percentage of 4.54%. The toughness of the film was 71.50 N.mm and the force required to rupture film was 16.49 N. The work and maximum force required to detach the mucoadhesive film from the glass side was 2.58 N.mm and 11615.32 mN, respectively. A Franz diffusion cell was used to perform acyclovir drug release studies from the mucoadhesive film and a commercial brand of acyclovir cream (Acitop®). Percentage acyclovir drug release from the film and cream was plotted against time using Sigmaplot® software version 13 following First order, Peppas, Hixon and Crowell, Higuchi (Square Root Time) and Bakers and Lonsdale mathematical models. The mucoadhesive film acyclovir attained the highest correlation coefficient r2 of 0.9879 following the Baker & Lonsdale mathematical model which describes controlled drug release from spherical matrices hence fits the model as the acyclovir is encapsulated in liposomes which are incorporated in the polymer mucoadhesive film. And the acyclovir cream (Acitop®) attained the highest correlation coefficient r2 of 0.9944 following the Peppas mathematical model. The Peppas model has been used to describe drug release from various release dosage forms when there is more than one type of dosage release or when release mechanism is not well known. One assumption of this model is that drug release occurs in one dimension, which is a suitable release profile for the cream as it is absorbed through the skin in one dimension when applied topically. There was significant difference between the drug release data for the mucoadhesive film and the acyclovir cream (Acitop®). A physically stable mucoadhesive film containing acyclovir-loaded liposomes was developed.
- Full Text:
- Date Issued: 2017
- Authors: Nalungwe, Sarah
- Date: 2017
- Subjects: Clinical pharmacology , Liposomes Nanomedicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14212 , vital:27451
- Description: Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The efficacy of oral acyclovir is limited as a result of its low bioavailability (15-30%) as it is poorly water soluble and therefore requires a frequent dosing regimen. When orally administered, peak plasma concentration occurs after 1.5–2.5 hours, while its elimination half-life is approximately 2-3 hours. Acyclovir displays poor solubility in water and in lipid bilayers, which leads to poor drug levels at target sites after oral, local, or parenteral administration. In order to improve this lack of solubility, novel amphiphilic derivatives have been designed to form nanoparticles, which allow for the efficient encapsulation of this hydrophobic antiviral agent. Reformulation of drugs in liposomes has provided an opportunity to enhance the therapeutic indices of various agents mainly via alteration of their bio-distribution. Liposomal drug delivery systems have received considerable attention due to their immense advantages which include, effective encapsulation of both small and large molecules that have a wide range of hydrophobicity levels and pKa values, prolonging and targeting release of therapeutic agents by modification of liposomal surface and also minimising clinical drug dose thus reducing toxicity effects. Liposomes exhibit a number of special biological characteristics, including specific interactions with biological membranes and various cells, hence, liposomes are used as biocompatible carriers to improve delivery properties across mucus membranes. Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for improved therapeutic outcome. The aim of this study was to develop an acyclovir liposomal mucoadhesive film by actively encapsulating acyclovir into liposomes and preparing a mucoadhesive film to optimise delivery of acyclovir liposomes at target sites. To actively encapsulate acyclovir and prepare the acyclovir-containing liposomes, a comprehensive statistical methodology was used in optimising the liposome formulation to encapsulate acyclovir. Central composite design was used as the response surface methodology statistical tool to design and develop an optimised method for active encapsulation of acyclovir into liposomes. The predicted optimised encapsulation parameters were incubation temperature of 60 °C and incubation time of 45 minutes. The mean percentage encapsulation calculated was 27.72%. The overall average size of the liposomes was 99.5 nm with a narrow distribution polydispersity index of 0.105 and were physically characterised as small unilamellar vesicles which possessed an average zeta potential of -45.6 mV. High Performance Liquid Chromatography (HPLC) was used to analyse and determine acyclovir drug content in the liposomes and drug release pattern from the mucoadhesive film. Polyvinyl-pyrrolidone (PVP) and Polyethylene glycol (PEG) were used in the preparation of mucoadhesive film, in which the acyclovir encapsulated liposomes were incorporated. The average amount of acyclovir drug content quantified to be in 4 cm2 of the mucoadhesive film was 36.8543 μg. The average tensile strength of the mucoadhesive film was determined to be 3.06 N/mm2 with an elongation percentage of 4.54%. The toughness of the film was 71.50 N.mm and the force required to rupture film was 16.49 N. The work and maximum force required to detach the mucoadhesive film from the glass side was 2.58 N.mm and 11615.32 mN, respectively. A Franz diffusion cell was used to perform acyclovir drug release studies from the mucoadhesive film and a commercial brand of acyclovir cream (Acitop®). Percentage acyclovir drug release from the film and cream was plotted against time using Sigmaplot® software version 13 following First order, Peppas, Hixon and Crowell, Higuchi (Square Root Time) and Bakers and Lonsdale mathematical models. The mucoadhesive film acyclovir attained the highest correlation coefficient r2 of 0.9879 following the Baker & Lonsdale mathematical model which describes controlled drug release from spherical matrices hence fits the model as the acyclovir is encapsulated in liposomes which are incorporated in the polymer mucoadhesive film. And the acyclovir cream (Acitop®) attained the highest correlation coefficient r2 of 0.9944 following the Peppas mathematical model. The Peppas model has been used to describe drug release from various release dosage forms when there is more than one type of dosage release or when release mechanism is not well known. One assumption of this model is that drug release occurs in one dimension, which is a suitable release profile for the cream as it is absorbed through the skin in one dimension when applied topically. There was significant difference between the drug release data for the mucoadhesive film and the acyclovir cream (Acitop®). A physically stable mucoadhesive film containing acyclovir-loaded liposomes was developed.
- Full Text:
- Date Issued: 2017
Development of a MPEG-7 based multimedia content description and retrieval tool for internet protocol television (IPTV)
- Ncube, Prince Daughing Ngqabutho
- Authors: Ncube, Prince Daughing Ngqabutho
- Date: 2017
- Subjects: MPEG (Video coding standard) Digital television Multimedia communications
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/4893 , vital:28738
- Description: Search and retrieval of multimedia content from open platforms such as the Internet and IPTV platforms has long been found to be hugely inefficient. It has been noted that a major cause of such inefficient results is the improper labeling or incomplete description of multimedia content by its creators. The lack of adequate description of video content by the proper annotation of video content with the relevant metadata leads to poor search and retrieval yields. The creation of such metadata itself is a major problem as there are various metadata description standards which users could employ. On the other hand there are tools such as FFprobe that can retrieve important features of video that can be used in searching and retrieval. The combination of such tools and metadata description standards could be the solution to the metadata problem. The Multimedia Content Description Interface (MPEG-7) is an example of a metadata description standard. It has been adopted by TISPAN for the description of IPTV multimedia content. The MPEG-7 standard is rather complex, seeing as it has over 1200 global Descriptors and Description Schemes which a user would have to know in order to implement such technology. This complexity is a nuisance when we consider the existence of multitudes of amateur video producers. These multimedia content creators have no idea how to use the MPEG-7 standard to annotate their creations with metadata. Consequently, overloading of the IPTV platform with content that has not been annotated in a standardized manner occurs, making search and retrieval of the multimedia content (videos, in this instance) inefficient. Therefore, it was imperative to try and determine whether the use of the MPEG-7 standard could be made much easier by creating a tool that is MPEG-7 enabled which will allow for the annotation of video content by any user without concerning themselves about how to use the MPEG-7 standard. In attempting to develop a tool for metadata generation, it was incumbent for us to understand the issues associated with metadata generation for users wishing to create IPTV services. An extensive literature review on IPTV standardization was carried out to determine the issues associated with metadata generation for IPTV and their proposed solutions. An experimental research approach was taken in an attempt to figure out if our proposed solution to the lack of technical expertise by users about the MPEG-7 standard could be the final solution to the metadata generation problem. We developed a Multimedia Content Description and Management System (MCDMS) prototype which enabled us to describe video content by annotating it with 16 different metadata elements and storing the descriptions in XML MPEG-7 format. Incremental development and re-use oriented development were used during the development phase of this research. The MCDMS underwent functional testing; smoke testing of the individual system components and Big Bang integration testing for the combined components. Our results indicate that the more metadata is appended to a video as description the better it is to search for and retrieve. The MCDMS hides the complexity of MPEG-7 metadata creation from the users. With the effortless creation of MPEG-7 based metadata, it becomes easier to annotate videos. Consequently, search and retrieval of video content becomes more efficient. It is important to note that the description of multimedia content remains a complex feat. Even with the metadata elements laid out for users, there still exist other issues that affect metadata creation such as polysemy and the semantic gap. However, the provision of a tool that does the MPEG-7 standardizing behind the scenes for users when they upload a video makes the description of multimedia content in a standardized manner a much easier feat to achieve.
- Full Text:
- Date Issued: 2017
- Authors: Ncube, Prince Daughing Ngqabutho
- Date: 2017
- Subjects: MPEG (Video coding standard) Digital television Multimedia communications
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/4893 , vital:28738
- Description: Search and retrieval of multimedia content from open platforms such as the Internet and IPTV platforms has long been found to be hugely inefficient. It has been noted that a major cause of such inefficient results is the improper labeling or incomplete description of multimedia content by its creators. The lack of adequate description of video content by the proper annotation of video content with the relevant metadata leads to poor search and retrieval yields. The creation of such metadata itself is a major problem as there are various metadata description standards which users could employ. On the other hand there are tools such as FFprobe that can retrieve important features of video that can be used in searching and retrieval. The combination of such tools and metadata description standards could be the solution to the metadata problem. The Multimedia Content Description Interface (MPEG-7) is an example of a metadata description standard. It has been adopted by TISPAN for the description of IPTV multimedia content. The MPEG-7 standard is rather complex, seeing as it has over 1200 global Descriptors and Description Schemes which a user would have to know in order to implement such technology. This complexity is a nuisance when we consider the existence of multitudes of amateur video producers. These multimedia content creators have no idea how to use the MPEG-7 standard to annotate their creations with metadata. Consequently, overloading of the IPTV platform with content that has not been annotated in a standardized manner occurs, making search and retrieval of the multimedia content (videos, in this instance) inefficient. Therefore, it was imperative to try and determine whether the use of the MPEG-7 standard could be made much easier by creating a tool that is MPEG-7 enabled which will allow for the annotation of video content by any user without concerning themselves about how to use the MPEG-7 standard. In attempting to develop a tool for metadata generation, it was incumbent for us to understand the issues associated with metadata generation for users wishing to create IPTV services. An extensive literature review on IPTV standardization was carried out to determine the issues associated with metadata generation for IPTV and their proposed solutions. An experimental research approach was taken in an attempt to figure out if our proposed solution to the lack of technical expertise by users about the MPEG-7 standard could be the final solution to the metadata generation problem. We developed a Multimedia Content Description and Management System (MCDMS) prototype which enabled us to describe video content by annotating it with 16 different metadata elements and storing the descriptions in XML MPEG-7 format. Incremental development and re-use oriented development were used during the development phase of this research. The MCDMS underwent functional testing; smoke testing of the individual system components and Big Bang integration testing for the combined components. Our results indicate that the more metadata is appended to a video as description the better it is to search for and retrieve. The MCDMS hides the complexity of MPEG-7 metadata creation from the users. With the effortless creation of MPEG-7 based metadata, it becomes easier to annotate videos. Consequently, search and retrieval of video content becomes more efficient. It is important to note that the description of multimedia content remains a complex feat. Even with the metadata elements laid out for users, there still exist other issues that affect metadata creation such as polysemy and the semantic gap. However, the provision of a tool that does the MPEG-7 standardizing behind the scenes for users when they upload a video makes the description of multimedia content in a standardized manner a much easier feat to achieve.
- Full Text:
- Date Issued: 2017
Development of an automatic news summarizer for isiXhosa language
- Authors: Ndyalivana, Zukile
- Date: 2017
- Subjects: Text processing (Computer science) Automatic abstracting Computational linguistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7875 , vital:30783
- Description: From practice perspective, given the abundance of digital content nowadays, coming up with a technological solution that summarizes written text without losing its message, coherence and cohesion of ideas is highly essential. The technology saves time for readers as well as gives them a chance to focus on the contents that matter most. This is one of the research areas in natural language processing/ information retrieval, which the dissertation tries to contribute to. It tries to contextualize tools and technologies that are developed for other languages to automatically summarize textual Xhosa news articles. Specifically, the dissertation aims at developing a text summarizer for textual Xhosa news articles based on the extraction methods. In doing so, it examines the literature and understand the techniques and technologies used to analyse contents of a written text, transform and synthesize it, the phonology and morphology of the Xhosa language, and finally, designs, implements and test an extraction-based automatic news article for the Xhosa language. Given comprehension and relevance of the literature review, the research design, the methods and tools and technologies used to design, implement and test the pilot system. Two approaches were used to extract relevant sentences, which are, term frequency and sentence position. The Xhosa summarizer is evaluated using a test set. This study has employed both subjective and objective evaluation methods. The results of both methods are satisfactory. Keywords: Xhosa, Automatic Text Summarization, Term Frequency and Sentence Position.
- Full Text:
- Date Issued: 2017
- Authors: Ndyalivana, Zukile
- Date: 2017
- Subjects: Text processing (Computer science) Automatic abstracting Computational linguistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7875 , vital:30783
- Description: From practice perspective, given the abundance of digital content nowadays, coming up with a technological solution that summarizes written text without losing its message, coherence and cohesion of ideas is highly essential. The technology saves time for readers as well as gives them a chance to focus on the contents that matter most. This is one of the research areas in natural language processing/ information retrieval, which the dissertation tries to contribute to. It tries to contextualize tools and technologies that are developed for other languages to automatically summarize textual Xhosa news articles. Specifically, the dissertation aims at developing a text summarizer for textual Xhosa news articles based on the extraction methods. In doing so, it examines the literature and understand the techniques and technologies used to analyse contents of a written text, transform and synthesize it, the phonology and morphology of the Xhosa language, and finally, designs, implements and test an extraction-based automatic news article for the Xhosa language. Given comprehension and relevance of the literature review, the research design, the methods and tools and technologies used to design, implement and test the pilot system. Two approaches were used to extract relevant sentences, which are, term frequency and sentence position. The Xhosa summarizer is evaluated using a test set. This study has employed both subjective and objective evaluation methods. The results of both methods are satisfactory. Keywords: Xhosa, Automatic Text Summarization, Term Frequency and Sentence Position.
- Full Text:
- Date Issued: 2017
Development of an item bank of health literacy questions appropriate for limited literacy public sector patients in South Africa:
- Marimwe, Chipiwa, Dowse, Roslind
- Authors: Marimwe, Chipiwa , Dowse, Roslind
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156618 , vital:40031 , https://doi.org/10.1080/17538068.2017.1380577
- Description: The majority of current health literacy measures emanate from high-income countries. In South Africa, there is no appropriate measure available for use by the diverse public sector population, many of whom have some literacy limitations. The objective was to develop a bank of questions for this population informed by a broader definition of health literacy, which acknowledges both traditional cognitive skills and explores the influence of the collective social environment on health literacy. Thirty questions for the Item Bank were developed to ensure cultural, contextual and educational appropriateness, and were continuously subjected to critical review by an expert consultant panel. Patients (n = 120) were recruited from a local primary care clinic and individually interviewed with the assistance of an interpreter to collect data on the Item Bank, Multidimensional Screener of Functional Health Literacy (MSFHL) and sociodemographics.
- Full Text:
- Date Issued: 2017
- Authors: Marimwe, Chipiwa , Dowse, Roslind
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156618 , vital:40031 , https://doi.org/10.1080/17538068.2017.1380577
- Description: The majority of current health literacy measures emanate from high-income countries. In South Africa, there is no appropriate measure available for use by the diverse public sector population, many of whom have some literacy limitations. The objective was to develop a bank of questions for this population informed by a broader definition of health literacy, which acknowledges both traditional cognitive skills and explores the influence of the collective social environment on health literacy. Thirty questions for the Item Bank were developed to ensure cultural, contextual and educational appropriateness, and were continuously subjected to critical review by an expert consultant panel. Patients (n = 120) were recruited from a local primary care clinic and individually interviewed with the assistance of an interpreter to collect data on the Item Bank, Multidimensional Screener of Functional Health Literacy (MSFHL) and sociodemographics.
- Full Text:
- Date Issued: 2017
Development of antibiotic loaded liposomal hydrocolloid dressings for application in wound healing
- Authors: Ntsalu, Vuyiseka
- Date: 2017
- Subjects: Wound healing -- South Africa Liposomes Hydrocolloid surgical dressings -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13957 , vital:27361
- Description: Wound healing, as a normal biological process in the human body, is achieved through four precise and highly programmed phases: hemostasis, inflammation, proliferation, and remodeling. For a wound to heal successfully, all four phases must occur in the proper sequence and time frame. However, many factors can interfere with one or more of these phases, thus causing improper or impaired wound healing. Maintaining a moist wound environment is crucial in facilitating the wound-healing process. The beneficial effects of a moist versus a dry wound environment include re-epithelization, tissue granulation, and repair. The use of hydrocolloid occlusive dressings in maintaining a moist wound environment has proven to be a useful adjunct in facilitating wound healing. Although hydrocolloid dressings have been widely used clinically in wound management, bacterial resistance, poor solubility and sustained drug release remain to be a problem for many of the drugs used in wound therapy. In chronic wound management, where patients normally undergo long treatments and frequent dressing changes, a system that delivers drugs into a wound site in a controlled fashion can improve patient compliance and therapeutic outcomes. Liposomes are small phospholipid vesicles that have been widely investigated as drug carriers for the delivery of therapeutic agents. They are spherical lipid vesicles consisting of phospholipid bilayers that improve the efficacy of the drugs by fusing with biological membranes, and eventually releasing their entrapped content into the cells or bacteria. The aim of this study therefore, is to develop a new bacitracin-based controlled release hydrocolloid dressing, with good absorptive properties for improving the efficacy of antibiotics in wound healing. HPLC (high-pressure liquid chromatography) assay of bacitracin was performed for quantification of the drug. Liposomes were prepared using thin film hydration and extrusion methods. Liposomes were also characterized based on their ideal particle size and encapsulation efficiency, and then incorporated into the different ratios of chitosan/gelatin hydrocolloid films. The films were prepared with increase in gelatin concentration and were evaluated for folding endurance, tensile strength, water absorption capacity, morphology, drug release kinetics, antimicrobial activity and stability. The morphology of these films was found to be very smooth and homogeneous proving a good compatibility between the two polymers. With increase in gelatin concentration, folding endurance, water absorption capacity, tensile strength, drug release kinetics and antimicrobial activity were increased. The antibacterial activity against various bacterial species was improved in the bacitracin loaded hydrocolloid films as compared to the blank films. Based on the findings above, it can be concluded that chitosan/gelatin films at 1:3 proportion is a successful wound dressing for wound management with improved wound healing properties than other formulations. This formulation is a potential candidate for the development of alternative pharmaceutical dosage forms, for the treatment of bacterial infected wounds, based on the activity of the eco-friendly chitosan matrix added to the bacitracin activity. In this work, chitosan also demonstrated a great potential as a dressing for advanced wound therapy and confirmed its good biocompatibility and potential to provide, in combination with liposomes, sustained drug release which is highly beneficial for wound treatment. The addition of gelatin improved the water affinity of the films and facilitated water mediated cross-linking process.
- Full Text:
- Date Issued: 2017
- Authors: Ntsalu, Vuyiseka
- Date: 2017
- Subjects: Wound healing -- South Africa Liposomes Hydrocolloid surgical dressings -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13957 , vital:27361
- Description: Wound healing, as a normal biological process in the human body, is achieved through four precise and highly programmed phases: hemostasis, inflammation, proliferation, and remodeling. For a wound to heal successfully, all four phases must occur in the proper sequence and time frame. However, many factors can interfere with one or more of these phases, thus causing improper or impaired wound healing. Maintaining a moist wound environment is crucial in facilitating the wound-healing process. The beneficial effects of a moist versus a dry wound environment include re-epithelization, tissue granulation, and repair. The use of hydrocolloid occlusive dressings in maintaining a moist wound environment has proven to be a useful adjunct in facilitating wound healing. Although hydrocolloid dressings have been widely used clinically in wound management, bacterial resistance, poor solubility and sustained drug release remain to be a problem for many of the drugs used in wound therapy. In chronic wound management, where patients normally undergo long treatments and frequent dressing changes, a system that delivers drugs into a wound site in a controlled fashion can improve patient compliance and therapeutic outcomes. Liposomes are small phospholipid vesicles that have been widely investigated as drug carriers for the delivery of therapeutic agents. They are spherical lipid vesicles consisting of phospholipid bilayers that improve the efficacy of the drugs by fusing with biological membranes, and eventually releasing their entrapped content into the cells or bacteria. The aim of this study therefore, is to develop a new bacitracin-based controlled release hydrocolloid dressing, with good absorptive properties for improving the efficacy of antibiotics in wound healing. HPLC (high-pressure liquid chromatography) assay of bacitracin was performed for quantification of the drug. Liposomes were prepared using thin film hydration and extrusion methods. Liposomes were also characterized based on their ideal particle size and encapsulation efficiency, and then incorporated into the different ratios of chitosan/gelatin hydrocolloid films. The films were prepared with increase in gelatin concentration and were evaluated for folding endurance, tensile strength, water absorption capacity, morphology, drug release kinetics, antimicrobial activity and stability. The morphology of these films was found to be very smooth and homogeneous proving a good compatibility between the two polymers. With increase in gelatin concentration, folding endurance, water absorption capacity, tensile strength, drug release kinetics and antimicrobial activity were increased. The antibacterial activity against various bacterial species was improved in the bacitracin loaded hydrocolloid films as compared to the blank films. Based on the findings above, it can be concluded that chitosan/gelatin films at 1:3 proportion is a successful wound dressing for wound management with improved wound healing properties than other formulations. This formulation is a potential candidate for the development of alternative pharmaceutical dosage forms, for the treatment of bacterial infected wounds, based on the activity of the eco-friendly chitosan matrix added to the bacitracin activity. In this work, chitosan also demonstrated a great potential as a dressing for advanced wound therapy and confirmed its good biocompatibility and potential to provide, in combination with liposomes, sustained drug release which is highly beneficial for wound treatment. The addition of gelatin improved the water affinity of the films and facilitated water mediated cross-linking process.
- Full Text:
- Date Issued: 2017
Development of aquaculture practitioner’s business skills to enhance income sustainability
- Authors: Koyo, Sichumile
- Date: 2017
- Subjects: Aquaculture industry -- South Africa -- Eastern Cape -- Management , Success in business -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape Economic development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18025 , vital:28561
- Description: The Eastern Cape Province is endowed with numerous aquatic resources with aquaculture potential. Farmers in suitable areas across the province are turning to fish farming as a way of producing high quality food, either for their families or for the market, and as a way of earning extra income. This research study therefore sought to examine the business management skills of the current aquaculture practitioners in the province as to enhance them. Literature reviewed showed that various business management skills that an aquaculture practitioner is required to have in order to enhance income sustainability. The business management that seemed to be of importance in enhancing income generation were identified, and those included, marketing management skills, financial management skills, operations management skills, and supporting skills which include, computer skills, technical skills , negotiation and time management skills. The study employed descriptive survey design and stratified sampling design was used in order to select a sample size of 55 respondents. The study adopted online survey questionnaires as instruments of data collection. Quantitative research approach then took place from chapter three in the empirical data collection, analysis and interpretation. Data collection tool was the constructed using the developed theoretical framework to determine the perception about the level of business management skills of aquaculture practitioners. Data was then collected using an online survey because it was seen as convenient and time saving to the researcher. The collected data was the recorded, organised and cleaned. The necessary statistical calculations which include; Pearson r counts, mean, mode, median, standard deviations, percentiles, chi-square, Spearman rank and percentages were performed. These statistical analyses were used to describe and interpreted the data. The findings indicate that the most aquaculture practitioners are the middle aged people from the age group 45 to 50 years. The results also show that the present aquaculture practitioners marketing management skills are still not considered in the aquaculture business because in the aquaculture industry there is currently less advertising as the demand for the products surpasses the production. The marketing management skills elements that appeared to be low negative include, considering the needs of the market, identifying target market, working out marketing strategy and finding ways to do better that the competition. The findings also indicate that the respondents also seem not to be confident about applying their personal life skill like time management and negotiation skills. The majority the respondents have on average had received education training in Honours/B.Tech Degree qualification. More of the respondents had on average worked more than 11 years. The abalone industry aquaculture sub-sector seems to be the most dominating sub sector.
- Full Text:
- Date Issued: 2017
- Authors: Koyo, Sichumile
- Date: 2017
- Subjects: Aquaculture industry -- South Africa -- Eastern Cape -- Management , Success in business -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape Economic development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18025 , vital:28561
- Description: The Eastern Cape Province is endowed with numerous aquatic resources with aquaculture potential. Farmers in suitable areas across the province are turning to fish farming as a way of producing high quality food, either for their families or for the market, and as a way of earning extra income. This research study therefore sought to examine the business management skills of the current aquaculture practitioners in the province as to enhance them. Literature reviewed showed that various business management skills that an aquaculture practitioner is required to have in order to enhance income sustainability. The business management that seemed to be of importance in enhancing income generation were identified, and those included, marketing management skills, financial management skills, operations management skills, and supporting skills which include, computer skills, technical skills , negotiation and time management skills. The study employed descriptive survey design and stratified sampling design was used in order to select a sample size of 55 respondents. The study adopted online survey questionnaires as instruments of data collection. Quantitative research approach then took place from chapter three in the empirical data collection, analysis and interpretation. Data collection tool was the constructed using the developed theoretical framework to determine the perception about the level of business management skills of aquaculture practitioners. Data was then collected using an online survey because it was seen as convenient and time saving to the researcher. The collected data was the recorded, organised and cleaned. The necessary statistical calculations which include; Pearson r counts, mean, mode, median, standard deviations, percentiles, chi-square, Spearman rank and percentages were performed. These statistical analyses were used to describe and interpreted the data. The findings indicate that the most aquaculture practitioners are the middle aged people from the age group 45 to 50 years. The results also show that the present aquaculture practitioners marketing management skills are still not considered in the aquaculture business because in the aquaculture industry there is currently less advertising as the demand for the products surpasses the production. The marketing management skills elements that appeared to be low negative include, considering the needs of the market, identifying target market, working out marketing strategy and finding ways to do better that the competition. The findings also indicate that the respondents also seem not to be confident about applying their personal life skill like time management and negotiation skills. The majority the respondents have on average had received education training in Honours/B.Tech Degree qualification. More of the respondents had on average worked more than 11 years. The abalone industry aquaculture sub-sector seems to be the most dominating sub sector.
- Full Text:
- Date Issued: 2017
Development of Bioinformatics Infrastructure for Genomics Research:
- Mulder, Nicola J, Adebiyi, Ezekiel, Adebiyi, Marion, Adeyemi, Seun, Ahmed, Azza, Ahmed, Rehab, Akanle, Bola, Alibi, Mohamed, Armstrong, Don L, Aron, Shaun, Ashano, Efejiro, Baichoo, Shakuntala, Benkahla, Alia, Brown, David K, Chimusa, Emile Rugamika, Fadlelmola, Faisal M, Falola, Dare, Fatumo, Segun, Ghedira, Kais, Ghouila, Amel, Hazelhurst, Scott, Itunuoluwa Isewon, Segun Jung, Kassim, Samar Kamal, Kayondo, Jonathan K, Mbiyavanga, Mamana, Meintjes, Ayton, Mohammed, Somia, Mosaku, Abayomi, Moussa, Ahmed, Muhammd, Mustafa, Mungloo-Dilmohamud, Zahra, Nashiru, Oyekanmi, Odia, Trust, Okafor, Adaobi, Oladipo, Olaleye, Osamor, Victor, Oyelade, Jellili, Sadki, Khalid, Salifu, Samson Pandam, Soyemi, Jumoke, Panji, Sumir, Radouani, Fouzia, Souiai, Oussama, Tastan Bishop, Özlem
- Authors: Mulder, Nicola J , Adebiyi, Ezekiel , Adebiyi, Marion , Adeyemi, Seun , Ahmed, Azza , Ahmed, Rehab , Akanle, Bola , Alibi, Mohamed , Armstrong, Don L , Aron, Shaun , Ashano, Efejiro , Baichoo, Shakuntala , Benkahla, Alia , Brown, David K , Chimusa, Emile Rugamika , Fadlelmola, Faisal M , Falola, Dare , Fatumo, Segun , Ghedira, Kais , Ghouila, Amel , Hazelhurst, Scott , Itunuoluwa Isewon , Segun Jung , Kassim, Samar Kamal , Kayondo, Jonathan K , Mbiyavanga, Mamana , Meintjes, Ayton , Mohammed, Somia , Mosaku, Abayomi , Moussa, Ahmed , Muhammd, Mustafa , Mungloo-Dilmohamud, Zahra , Nashiru, Oyekanmi , Odia, Trust , Okafor, Adaobi , Oladipo, Olaleye , Osamor, Victor , Oyelade, Jellili , Sadki, Khalid , Salifu, Samson Pandam , Soyemi, Jumoke , Panji, Sumir , Radouani, Fouzia , Souiai, Oussama , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148239 , vital:38722 , DOI: 10.1016/j.gheart.2017.01.005
- Description: Although pockets of bioinformatics excellence have developed in Africa, generally, large-scale genomic data analysis has been limited by the availability of expertise and infrastructure. H3ABioNet, a pan-African bioinformatics network, was established to build capacity specifically to enable H3Africa (Human Heredity and Health in Africa) researchers to analyze their data in Africa. Since the inception of the H3Africa initiative, H3ABioNet's role has evolved in response to changing needs from the consortium and the African bioinformatics community.
- Full Text:
- Date Issued: 2017
- Authors: Mulder, Nicola J , Adebiyi, Ezekiel , Adebiyi, Marion , Adeyemi, Seun , Ahmed, Azza , Ahmed, Rehab , Akanle, Bola , Alibi, Mohamed , Armstrong, Don L , Aron, Shaun , Ashano, Efejiro , Baichoo, Shakuntala , Benkahla, Alia , Brown, David K , Chimusa, Emile Rugamika , Fadlelmola, Faisal M , Falola, Dare , Fatumo, Segun , Ghedira, Kais , Ghouila, Amel , Hazelhurst, Scott , Itunuoluwa Isewon , Segun Jung , Kassim, Samar Kamal , Kayondo, Jonathan K , Mbiyavanga, Mamana , Meintjes, Ayton , Mohammed, Somia , Mosaku, Abayomi , Moussa, Ahmed , Muhammd, Mustafa , Mungloo-Dilmohamud, Zahra , Nashiru, Oyekanmi , Odia, Trust , Okafor, Adaobi , Oladipo, Olaleye , Osamor, Victor , Oyelade, Jellili , Sadki, Khalid , Salifu, Samson Pandam , Soyemi, Jumoke , Panji, Sumir , Radouani, Fouzia , Souiai, Oussama , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148239 , vital:38722 , DOI: 10.1016/j.gheart.2017.01.005
- Description: Although pockets of bioinformatics excellence have developed in Africa, generally, large-scale genomic data analysis has been limited by the availability of expertise and infrastructure. H3ABioNet, a pan-African bioinformatics network, was established to build capacity specifically to enable H3Africa (Human Heredity and Health in Africa) researchers to analyze their data in Africa. Since the inception of the H3Africa initiative, H3ABioNet's role has evolved in response to changing needs from the consortium and the African bioinformatics community.
- Full Text:
- Date Issued: 2017
Development of conservation strategies for Alepidea Amatymbica ECKL. & ZEYH. : a rare medicinal plant in the Eastern Cape, South Africa
- Mangoale, Ramatsobane Maureen
- Authors: Mangoale, Ramatsobane Maureen
- Date: 2017
- Subjects: Medicinal plants Plants, Cultivated
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/8667 , vital:33400
- Description: Conservation through cultivation has been recommended as a means to relieve overexploitation of medicinal plants. However, the medicinal plants users believe that plants collected from the wild are more potent than cultivated ones. Hence, there is a need for scientific documentation of the potency of cultivated medicinal plants to contribute to the development of a sustainable management strategy to conserve wild populations. This study was aimed at documenting cultivation techniques of a known medicinal plant, Alepidea amatymbica and to validate its medicinal efficacy. In order to identify overexploited medicinal plants in the study area and thus develop their conservation strategy, a survey on the trade of medicinal plants was conducted in selected towns of Amathole District Municipality of the Eastern Cape, South Africa. The survey revealed 67 plants belonging to 46 different families. Twenty-five medicinal plants were identified as overexploited and scarce and they were prioritized for conservation. Furthermore, 69.14 percent of the respondents were not willing to use cultivated medicinal plants. Lack of belief on the potency of cultivated plants and cultivation techniques were mentioned as the most significant constraints to conservation of medicinal plants. Also, the time for cultivated plants to reach maturity deterred herbal medicine practitioners from cultivating them. Alepidea amatymbica was mentioned as one of the most overexploited medicinal plants which has become scarce in the study area. This medicinal plant was therefore selected for this study. In order to develop sustainable conservation program for the species, various studies which include survey on the medicinal plants trade, cultivation, comparative micromorphology, elemental composition, toxicity, phytochemical and antioxidant activity of the wild and cultivated A. amatymbica were conducted. Cultivation of Alepidea amatymbica was conducted to determine the appropriate planting depth and rhizome fragment length for the growth of this plant. The experiment was laid out in a Complete Randomized Block Design (CRBD) with two factors in 6×3 factorial design. There were six levels of fragment length (1, 2, 3, 4, 5 and 6 cm) and three levels of burial depth (2.5, 5 and 7.5 cm). Emergence rate, number of leaves, leaf area, and plant height, number of florets, rhizome length gain, rhizome weight gain, shoot moisture and rhizome moisture were measured as growth parameters. The best overall yield in terms of plant height, shoot emergence, rhizome weight gain, number of florets and number of leaves was observed in 7.5 cm planting depth at 6 cm rhizome length. Four centimetre rhizome length had the highest leaf area of 111.9±3.5 cm2, 101.3±3.5 cm2, 105±3.5 cm2 at 2.5, 5, 7.5 cm planting depth respectively. Shorter fragment lengths showed high potential for vegetative propagation in terms of rhizome length gain at all burial depths. Scanning electron microscopy (SEM) was used to examine the foliar micro morphological characteristics while energy dispersive x-ray spectroscopy (EDXS) was used to determine the elemental composition in different parts of the wild and cultivated plants. The study revealed numerous differences between the wild and cultivated ones. These include deposition of epicuticular waxes, stomatal apparatus, helical thickening of the xylem walls, thickening of the epidermal cell layer and presence of starch grains in the parenchyma cells of the cortex. The EDXS analysis also revealed disproportionate quantities of C, O, Ca, K, Al, Mg, Si, Br and N as the major constituents in both cultivated and wild A. amatymbica specimens. The quantities of elements varied in the different parts of wild and cultivated plants. Toxicity of the methanol, water and acetone extracts of the fresh rhizome of the wild and cultivated A. amatymbica were evaluated using hatchability of cysts and lethality on the hatched cysts (nauplii) of Artemia salina. The highest hatching success was observed in the water extracts of the wild plant (46.16percent) with a MIC of 0.184 mg/ml while the cultivated plants had a hatching success of 40.83percent with MIC of 0.208 mg/ml. Highest mortality was observed in the acetone extract of the wild plants at the lethal dose of 0.191 mg/ml while the cultivated plant had a lethal dose of 0.270 mg/ml. Water extracts of both wild and cultivated plants showed similar lethal dose (LD50) of >1 mg/ml. Methanol extracts of both the wild and cultivated species exhibited almost the same level of toxicity (0.695 mg/ml and 0.628 mg/ml, respectively). Based on the Bastos criterion of toxicity indices of the lethality test, all the plant fractions demonstrated cytotoxicity effect, although the degree of their toxicity varied among the plants used. Standard spectrophotometry assays were used to quantify the phytochemical contents and to determine the antioxidant potentials of the cultivated and wild A. amatymbica. The results revealed different levels of phytochemicals with corresponding antioxidant activities. The wild extracts had higher phytochemical contents in most of the assays than cultivated extracts. Total phenol in the wild extracts ranged from 32.30±3.43 to 117.8±8.45 mg GAE/g with the acetone extracts having the highest content while the water extracts was the least. The range in the total phenol of the cultivated species was 66.46±5.29 to 98.44±6.08 mg GAE/g with the methanol extracts having the highest content while water extracts was the least. The flavonoids content ranged from 55.01±6.51 to 99.09±7.20 mg QE/mg and from 48.65±7.74 to 67.32±4.1 mg QE/mg for the wild and cultivated plants, respectively. The alkaloids contents ranged from 14.70±0.04 to 17.80±0.015 percent in the wild species while it ranged from 11.98±0.14 to 13.21±0.06 percent in the cultivated species. The wild species also showed higher antioxidant activities in most of the assays evaluated. The study revealed successful cultivation of the wild species of Alepidea amatymbica using fragments from the rhizome. The micromorphological study of both the wild and cultivated species showed minimal differences in the helical thickening of the walls in the xylem vessels and starch grain accumulation pattern. Although herbal medicine practitioners believe that cultivated species are not potent, however this study revealed some levels of phytochemicals contents and antioxidant activities which are comparable to the wild species. Cultivation is a major strategy in conserving nature and their resources. Hence, the successful domestication of A. amatymbica would help in reducing the pressure on the wild species while also meeting their medicinal demands purposes, utilisation and conserving for future generations.
- Full Text:
- Date Issued: 2017
- Authors: Mangoale, Ramatsobane Maureen
- Date: 2017
- Subjects: Medicinal plants Plants, Cultivated
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/8667 , vital:33400
- Description: Conservation through cultivation has been recommended as a means to relieve overexploitation of medicinal plants. However, the medicinal plants users believe that plants collected from the wild are more potent than cultivated ones. Hence, there is a need for scientific documentation of the potency of cultivated medicinal plants to contribute to the development of a sustainable management strategy to conserve wild populations. This study was aimed at documenting cultivation techniques of a known medicinal plant, Alepidea amatymbica and to validate its medicinal efficacy. In order to identify overexploited medicinal plants in the study area and thus develop their conservation strategy, a survey on the trade of medicinal plants was conducted in selected towns of Amathole District Municipality of the Eastern Cape, South Africa. The survey revealed 67 plants belonging to 46 different families. Twenty-five medicinal plants were identified as overexploited and scarce and they were prioritized for conservation. Furthermore, 69.14 percent of the respondents were not willing to use cultivated medicinal plants. Lack of belief on the potency of cultivated plants and cultivation techniques were mentioned as the most significant constraints to conservation of medicinal plants. Also, the time for cultivated plants to reach maturity deterred herbal medicine practitioners from cultivating them. Alepidea amatymbica was mentioned as one of the most overexploited medicinal plants which has become scarce in the study area. This medicinal plant was therefore selected for this study. In order to develop sustainable conservation program for the species, various studies which include survey on the medicinal plants trade, cultivation, comparative micromorphology, elemental composition, toxicity, phytochemical and antioxidant activity of the wild and cultivated A. amatymbica were conducted. Cultivation of Alepidea amatymbica was conducted to determine the appropriate planting depth and rhizome fragment length for the growth of this plant. The experiment was laid out in a Complete Randomized Block Design (CRBD) with two factors in 6×3 factorial design. There were six levels of fragment length (1, 2, 3, 4, 5 and 6 cm) and three levels of burial depth (2.5, 5 and 7.5 cm). Emergence rate, number of leaves, leaf area, and plant height, number of florets, rhizome length gain, rhizome weight gain, shoot moisture and rhizome moisture were measured as growth parameters. The best overall yield in terms of plant height, shoot emergence, rhizome weight gain, number of florets and number of leaves was observed in 7.5 cm planting depth at 6 cm rhizome length. Four centimetre rhizome length had the highest leaf area of 111.9±3.5 cm2, 101.3±3.5 cm2, 105±3.5 cm2 at 2.5, 5, 7.5 cm planting depth respectively. Shorter fragment lengths showed high potential for vegetative propagation in terms of rhizome length gain at all burial depths. Scanning electron microscopy (SEM) was used to examine the foliar micro morphological characteristics while energy dispersive x-ray spectroscopy (EDXS) was used to determine the elemental composition in different parts of the wild and cultivated plants. The study revealed numerous differences between the wild and cultivated ones. These include deposition of epicuticular waxes, stomatal apparatus, helical thickening of the xylem walls, thickening of the epidermal cell layer and presence of starch grains in the parenchyma cells of the cortex. The EDXS analysis also revealed disproportionate quantities of C, O, Ca, K, Al, Mg, Si, Br and N as the major constituents in both cultivated and wild A. amatymbica specimens. The quantities of elements varied in the different parts of wild and cultivated plants. Toxicity of the methanol, water and acetone extracts of the fresh rhizome of the wild and cultivated A. amatymbica were evaluated using hatchability of cysts and lethality on the hatched cysts (nauplii) of Artemia salina. The highest hatching success was observed in the water extracts of the wild plant (46.16percent) with a MIC of 0.184 mg/ml while the cultivated plants had a hatching success of 40.83percent with MIC of 0.208 mg/ml. Highest mortality was observed in the acetone extract of the wild plants at the lethal dose of 0.191 mg/ml while the cultivated plant had a lethal dose of 0.270 mg/ml. Water extracts of both wild and cultivated plants showed similar lethal dose (LD50) of >1 mg/ml. Methanol extracts of both the wild and cultivated species exhibited almost the same level of toxicity (0.695 mg/ml and 0.628 mg/ml, respectively). Based on the Bastos criterion of toxicity indices of the lethality test, all the plant fractions demonstrated cytotoxicity effect, although the degree of their toxicity varied among the plants used. Standard spectrophotometry assays were used to quantify the phytochemical contents and to determine the antioxidant potentials of the cultivated and wild A. amatymbica. The results revealed different levels of phytochemicals with corresponding antioxidant activities. The wild extracts had higher phytochemical contents in most of the assays than cultivated extracts. Total phenol in the wild extracts ranged from 32.30±3.43 to 117.8±8.45 mg GAE/g with the acetone extracts having the highest content while the water extracts was the least. The range in the total phenol of the cultivated species was 66.46±5.29 to 98.44±6.08 mg GAE/g with the methanol extracts having the highest content while water extracts was the least. The flavonoids content ranged from 55.01±6.51 to 99.09±7.20 mg QE/mg and from 48.65±7.74 to 67.32±4.1 mg QE/mg for the wild and cultivated plants, respectively. The alkaloids contents ranged from 14.70±0.04 to 17.80±0.015 percent in the wild species while it ranged from 11.98±0.14 to 13.21±0.06 percent in the cultivated species. The wild species also showed higher antioxidant activities in most of the assays evaluated. The study revealed successful cultivation of the wild species of Alepidea amatymbica using fragments from the rhizome. The micromorphological study of both the wild and cultivated species showed minimal differences in the helical thickening of the walls in the xylem vessels and starch grain accumulation pattern. Although herbal medicine practitioners believe that cultivated species are not potent, however this study revealed some levels of phytochemicals contents and antioxidant activities which are comparable to the wild species. Cultivation is a major strategy in conserving nature and their resources. Hence, the successful domestication of A. amatymbica would help in reducing the pressure on the wild species while also meeting their medicinal demands purposes, utilisation and conserving for future generations.
- Full Text:
- Date Issued: 2017
Developmental dynamics in land reform projects : comparative studies of two different land reform projects, farm-worker equity schemes and beneficiary-owned and run citrus projects
- Authors: Tiwana, Sebenzile Wilbert
- Date: 2017
- Subjects: Land reform -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/5047 , vital:29025
- Description: In this study, a comparison was made between two different land reform models in the Sarah Baartman District of the Eastern Cape to, firstly; evaluate and identify factors that influence long-term sustainability and prosperity of farms owned and run by beneficiaries, and farms jointly owned by beneficiaries and former farmer / mentor in a share equity scheme, referred to as Farmworkers Equity Share Schemes (FWES), and secondly; to identify forms of government support in each of the two models. Mixed methods were used to collect data for the study. It involved the administration of structured interviews to beneficiaries, and semi-structured interviews with the mentor and government officials. The study found that the equity share scheme improved the livelihood of the beneficiaries in terms of getting annual dividends and acquiring new properties, empowered beneficiaries in decision-making in terms of having a say in financial expenditure on farm operations and the structuring of dividend pay-outs, and the project showed great potential of long-term sustainability and prosperity. Conversely, the beneficiary-owned and run project did not improve the lives of beneficiaries, was prone to infighting and fraught with organisational and management problems with no prospects of long-term sustainability and economic viability.
- Full Text:
- Date Issued: 2017
- Authors: Tiwana, Sebenzile Wilbert
- Date: 2017
- Subjects: Land reform -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/5047 , vital:29025
- Description: In this study, a comparison was made between two different land reform models in the Sarah Baartman District of the Eastern Cape to, firstly; evaluate and identify factors that influence long-term sustainability and prosperity of farms owned and run by beneficiaries, and farms jointly owned by beneficiaries and former farmer / mentor in a share equity scheme, referred to as Farmworkers Equity Share Schemes (FWES), and secondly; to identify forms of government support in each of the two models. Mixed methods were used to collect data for the study. It involved the administration of structured interviews to beneficiaries, and semi-structured interviews with the mentor and government officials. The study found that the equity share scheme improved the livelihood of the beneficiaries in terms of getting annual dividends and acquiring new properties, empowered beneficiaries in decision-making in terms of having a say in financial expenditure on farm operations and the structuring of dividend pay-outs, and the project showed great potential of long-term sustainability and prosperity. Conversely, the beneficiary-owned and run project did not improve the lives of beneficiaries, was prone to infighting and fraught with organisational and management problems with no prospects of long-term sustainability and economic viability.
- Full Text:
- Date Issued: 2017
Devulcanization of model compounds by a variety of diphenyldisulfides
- Authors: Boyce, Annemè
- Date: 2017
- Subjects: Rubber -- Recycling Rubber, Reclaimed , Rubber -- Standards -- South Africa Rubber -- Research Chromatographic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14730 , vital:27834
- Description: Improvements to the properties of recycled rubber, by developing a more selective breakdown process, is an important issue and a global challenge. Devulcanization is the most promising way to achieve this. It is a process which aims to totally or partially cleave monosulfidic (C-S-C), disulfidic (C-S-S-C) and polysulfidic (C-Sx-C) crosslinks of vulcanized rubber. In this study, the devulcanization of sulfur-vulcanized natural rubber with a variety of diphenyldisulfides has been studied using 2,3-dimethyl-2-butene and squalene as model compounds, vulcanized by sulfur and 2-bisbenzothiazole-2,2’-disulfide. 2-aminodiphenyldisulfide; 4-amino-diphenyldisulfide; bis(2-benzamido-)diphenyldisulfide and 2,2’-bithiosalicylic acid were used as aromatic disulfides devulcanization agents. Thermal analysis was used to investigate interactions between various combinations of curatives in the vulcanization systems in the absence of model compounds. Thermogravimetric analysis was used to detect mass changes during vulcanization and whether the samples decompose/evaporate so as not to contaminate differential scanning calorimetry instrumentation. Differential scanning calorimetry was used to investigate reactions occurring between curatives. Comparison of reversing and non-reversing signals in modulated experiments are suggestive of reactions between devulcanization agents and sulfur, and accelerators Vulcanization of the model compounds were performed in 10m evacuated sealed glass ampoules placed in an oil bath at 160 °C and agitated for the duration of vulcanization. After 60 min the ampoules were removed and quenched. These were then devulcanized by exposure to a devulcanization agent in a sealed ampoule at 180 for 60 min. Crosslinked 2,3-dimethyl-2-butene species were isolated and analysed by reversed phase high performance liquid chromatography. Particular attention was paid to changes in the number of sulfur atoms in the crosslinks. Results indicate that of the devulcanization agents tested 4-amino-diphenyldisulfide was the most effective. No detrimental effect on devulcanization efficiency was caused by the substitution of a basic amino group with an acidic carboxylic acid group Gel permeation chromatography was performed on devulcanized squalene crosslinks using a tetrahydrofuran eluent. GPC investigations with squalene were less effective than HPLC experiments with 2,3-dimethyl-2-butene at evaluating the relative efficiency of individual devulcanization agents. Results were, however, consistent with 4-amino-diphenyldisulfide again being the most efficient devulcanization agent.
- Full Text:
- Date Issued: 2017
- Authors: Boyce, Annemè
- Date: 2017
- Subjects: Rubber -- Recycling Rubber, Reclaimed , Rubber -- Standards -- South Africa Rubber -- Research Chromatographic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14730 , vital:27834
- Description: Improvements to the properties of recycled rubber, by developing a more selective breakdown process, is an important issue and a global challenge. Devulcanization is the most promising way to achieve this. It is a process which aims to totally or partially cleave monosulfidic (C-S-C), disulfidic (C-S-S-C) and polysulfidic (C-Sx-C) crosslinks of vulcanized rubber. In this study, the devulcanization of sulfur-vulcanized natural rubber with a variety of diphenyldisulfides has been studied using 2,3-dimethyl-2-butene and squalene as model compounds, vulcanized by sulfur and 2-bisbenzothiazole-2,2’-disulfide. 2-aminodiphenyldisulfide; 4-amino-diphenyldisulfide; bis(2-benzamido-)diphenyldisulfide and 2,2’-bithiosalicylic acid were used as aromatic disulfides devulcanization agents. Thermal analysis was used to investigate interactions between various combinations of curatives in the vulcanization systems in the absence of model compounds. Thermogravimetric analysis was used to detect mass changes during vulcanization and whether the samples decompose/evaporate so as not to contaminate differential scanning calorimetry instrumentation. Differential scanning calorimetry was used to investigate reactions occurring between curatives. Comparison of reversing and non-reversing signals in modulated experiments are suggestive of reactions between devulcanization agents and sulfur, and accelerators Vulcanization of the model compounds were performed in 10m evacuated sealed glass ampoules placed in an oil bath at 160 °C and agitated for the duration of vulcanization. After 60 min the ampoules were removed and quenched. These were then devulcanized by exposure to a devulcanization agent in a sealed ampoule at 180 for 60 min. Crosslinked 2,3-dimethyl-2-butene species were isolated and analysed by reversed phase high performance liquid chromatography. Particular attention was paid to changes in the number of sulfur atoms in the crosslinks. Results indicate that of the devulcanization agents tested 4-amino-diphenyldisulfide was the most effective. No detrimental effect on devulcanization efficiency was caused by the substitution of a basic amino group with an acidic carboxylic acid group Gel permeation chromatography was performed on devulcanized squalene crosslinks using a tetrahydrofuran eluent. GPC investigations with squalene were less effective than HPLC experiments with 2,3-dimethyl-2-butene at evaluating the relative efficiency of individual devulcanization agents. Results were, however, consistent with 4-amino-diphenyldisulfide again being the most efficient devulcanization agent.
- Full Text:
- Date Issued: 2017
Diamond turning of contact lens polymers
- Authors: Liman, Muhammad Mukhtar
- Date: 2017
- Subjects: Diamond turning Contact lenses , Electrostatic lenses Lenses -- Design and construction Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/19223 , vital:28789
- Description: Contact lens production requires high accuracy and good surface integrity. Surface roughness is generally used to measure the index quality of a turning process. It has been an important response because it has direct influence toward the part performance and the production cost. Hence, choosing optimal cutting parameters will not only improve the quality measure but also the productivity. In this study, an ONSI-56 (Onsifocon A) contact lens buttons were used to investigate the triboelectric phenomena and the effects of turning parameters on surface finish of the lens materials. ONSI-56 specimens are machined by Precitech Nanoform Ultra-grind 250 precision machine and the roughness values of the diamond turned surfaces are measured by Taylor Hopson PGI Profilometer. Electrostatics values were measured using electrostatic voltmeter. An artificial neural network (ANN) and response surface (RS) model were developed to predict surface roughness and electrostatic discharge (ESD) on the turned ONSI-56. In the development of predictive models, turning parameters of cutting speed, feed rate and depth of cut were considered as model variables. The required data for predictive models were obtained by conducting a series of turning test and measuring the surface roughness and ESD data. Good agreement is observed between the predictive models results and the experimental measurements. The ANN and RSM models for ONSI-56 are compared with each other using mean absolute percentage error (MAPE) for accuracy and computational cost.
- Full Text:
- Date Issued: 2017
- Authors: Liman, Muhammad Mukhtar
- Date: 2017
- Subjects: Diamond turning Contact lenses , Electrostatic lenses Lenses -- Design and construction Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/19223 , vital:28789
- Description: Contact lens production requires high accuracy and good surface integrity. Surface roughness is generally used to measure the index quality of a turning process. It has been an important response because it has direct influence toward the part performance and the production cost. Hence, choosing optimal cutting parameters will not only improve the quality measure but also the productivity. In this study, an ONSI-56 (Onsifocon A) contact lens buttons were used to investigate the triboelectric phenomena and the effects of turning parameters on surface finish of the lens materials. ONSI-56 specimens are machined by Precitech Nanoform Ultra-grind 250 precision machine and the roughness values of the diamond turned surfaces are measured by Taylor Hopson PGI Profilometer. Electrostatics values were measured using electrostatic voltmeter. An artificial neural network (ANN) and response surface (RS) model were developed to predict surface roughness and electrostatic discharge (ESD) on the turned ONSI-56. In the development of predictive models, turning parameters of cutting speed, feed rate and depth of cut were considered as model variables. The required data for predictive models were obtained by conducting a series of turning test and measuring the surface roughness and ESD data. Good agreement is observed between the predictive models results and the experimental measurements. The ANN and RSM models for ONSI-56 are compared with each other using mean absolute percentage error (MAPE) for accuracy and computational cost.
- Full Text:
- Date Issued: 2017