Development of an M-commerce security framework
- Authors: Murufu, Mufudzi Anesu Chapman
- Date: 2014
- Subjects: Mobile commerce , Telecommunication systems
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: http://hdl.handle.net/10353/833 , vital:26501 , Mobile commerce , Telecommunication systems
- Description: Research shows how M-Commerce has managed to find its way to previously inaccessible parts of the world as a major Information and Communication Technologies (ICT) tool for development due to widespread introduction of mobile phones in remote areas. M-Commerce has offered valuable advantages: anytime, anywhere, more personal, more location-aware, more context-aware, more age aware, always online and instant connectivity. But this is not without its problems, of which security is high on the list. The security issues span the whole M-Commerce spectrum, from the top to the bottom layer of the OSI network protocol stack, from machines to humans. This research proposes a threat-mitigation modular framework to help address the security issues lurking in M-Commerce systems being used by marginalised rural community members. The research commences with a literature survey carried out to establish security aspects related to M-Commerce and to determine requirements for a security framework. The framework classifies M-Commerce security threat-vulnerability-risks into four levels: human behaviour and mobile device interaction security, mobile device security, M-Commerce access channel security, wireless network access security. This is followed by a review of the supporting structures or related frameworks that the proposed framework could leverage to address security issues on M-Commerce systems as ICT4D initiatives. The proposed security framework based on the requirements discovered is then presented. As a proof-of-concept, a case study was undertaken at the Siyakhula Living Lab at Dwesa in the Eastern Cape province of South Africa in order to validate the components of the proposed framework. Following the application of the framework in a case study, it can be argued that the proposed security framework allows for secure transacting by marginalised users using M-Commerce initiatives. The security framework is therefore useful in addressing the identified security requirements of M-Commerce in ICT4D contexts.
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Development of conservation methods for gunnera perpensa l.: an overexploited medicinal plant in the Eastern Cape, South Africa
- Authors: Chigor, Chinyere Blessing
- Date: 2014
- Subjects: Gunnera -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Medical anthropology -- South Africa -- Eastern Cape , Medical policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Botany)
- Identifier: vital:11311 , http://hdl.handle.net/10353/d1019832 , Gunnera -- South Africa -- Eastern Cape , Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Medical anthropology -- South Africa -- Eastern Cape , Medical policy -- South Africa -- Eastern Cape
- Description: South Africa, many plants which are used in traditional medicines are collected from wild populations. The high demand for trade and use of these medicinal plants place an enormous pressure on their natural populations, especially because they are indiscriminately harvested. The most affected of these plant species are those harvested from their underground parts, among which is Gunnera perpensa L. Gunnera perpensa is of considerable ethnobotanical interest in traditional medicine because of its wide usage. The rhizomes are widely used and indiscriminately collected in large quantities from the wild to meet the ever increasing demand in traditional medicine markets. As a result, this valuable medicinal plant species is being endangered. According to the Red List of South African Plants, the conservation status of G. perpensa has been listed as ‘declining’. The ethnobotanical survey conducted as part of this research confirms the plant species as threatened. It is, therefore, important to develop propagation and conservation strategies for this medicinal plant. Clonal propagation of G. perpensa was conducted using varying lengths of the rhizome (1, 2, 3, 4 and 5 cm) segments as propagules. While regeneration was possible with all the rhizome lengths, most of the growth parameters were significantly higher in the 5 cm rhizomes than the other rhizome segments. The appropriate planting depth for the rhizomes was also determined and 4 or 5 cm planting depths were found appropriate. No significant difference was observed in the growth parameters amongst the planting depths; nevertheless, 4 cm depth gave higher growth and yield. The results of this study show that regenerating G. perpensa.
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Dialogic pedagogical innovation for liberating learning practices: a case of one programme in a higher education institution in South Africa
- Authors: Mudehwe, Florence Rutendo
- Date: 2014
- Subjects: Educational change -- South Africa , School improvement programs -- South Africa , Critical pedagogy , Curriculum evaluation -- South Africa , Education --Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16225 , http://hdl.handle.net/10353/d1019737 , Educational change -- South Africa , School improvement programs -- South Africa , Critical pedagogy , Curriculum evaluation -- South Africa , Education --Study and teaching
- Description: The past two to three decades have seen unprecedented expansion in enrolments in Universities across the world. Increased participation rates in Higher Education, however, has not been matched by a corresponding increase in success rates as reflected in students' poor retention rates and unsatisfactory outcomes. One strand of explanation claims that students, for a variety of reasons, come to university `unprepared' and suffer an articulation gap in the transition between high school and university; the other explanation seeks to move away from the deficit perspective and puts emphasis on the need to enrich experiences of students to enable them to exercise agency and change constraining circumstances in order to succeed. This study reports on one programme, a grounding programme known as the Life, Knowledge and Action (LKA) in one South African university. One of the central purposes of the LKA is to enrich students' first year experiences through liberating dialogue embedded in its pedagogical architecture. A sequential mixed methods study was carried out. A survey of first year students who had been exposed to the LKA was first carried out. This was followed by a case study of purposively selected first year students. Findings show that LKA promoted dialogue in varied ways depending on the level of the pedagogical architecture. At Umzi level students as peers across disciplines exchanged ideas freely about their circumstances and social issues. At the Ekhaya level where the abakwezeli (facilitators) were active, power dynamics emerged between students and the facilitators which had the effect of diminishing dialogical moments. At village level, there was not much discussion; instead there was a lot of lecturing. Dialogue was limited to a few minutes of discussion at the end of the lecture. The other finding was that seen from Archer's lens of morphogenetic analysis, the `articulation gap' can be seen as a structural constraint, that can be addressed through liberating dialogue which enables the students to question the status quo. There was evidence that through dialogue in the LKA, students felt that it liberated them in the sense that it exposed them to different perspectives as well as enabled them to explore alternatives. It can be concluded that through an appropriately designed dialogical pedagogy, students can be empowered to transform the structural constraints to their education and create enablers that can help them succeed in their learning. There is evidence that within the LKA pedagogical architecture, the students have the opportunity to take responsibility for their learning and thus enabled to exercise agency. It is recommended that the processes that take place at each level of the LKA architecture must be further studied with a view to discovering mechanisms at work that may undermine the liberating thrust of the programme. As a liberating core curriculum, LKA must not be limited to first year students; consideration must be given to roll it out across the levels of the undergraduate offerings.
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Diet and microhabitat use of the woodland dormouse Graphiurus murinus at the Great Fish River Reserve, Eastern Cape, South Africa
- Authors: Lamani, Siviwe
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11797 , http://hdl.handle.net/10353/d1019854
- Description: The diet of the woodland dormouse Graphiurus murinus was studied in a riverine Combretum forest at the Great Fish River Reserve (Eastern Cape, South Africa). Food remains were collected seasonally from a maximum of 45 different nest boxes between December 2010 and November 2011. An overall mean of 1.32 ± 0.51 food categories (range 1–4) were identified in each nest box used as “larder” during the year. Dietary diversity and standardized diet breadth were low to intermediate, with a peak in summer and a nadir in winter. In terms of percentage occurrence, arthropods were dominant (99%) in all seasons, followed by molluscs (16%) and fruits (14%). When relative percentage occurrence and percentage weight were considered, arthropods were still dominant, but a slight decrease was observed in summer. Besides spiders (order Araneae), nine arthropod families were found in the diet of the woodland dormouse; Tenebrionidae (40%), Spirostreptidae (30%), Carabidae (15%) and Blattidae (14%) were the most dominant families in terms of percentage weight. Grewia robusta and Ziziphus mucronata were the only fruit species present in the diet. Pianka’s diet overlap indices were very high (>0.93), indicating that the diet of the woodland dormouse was similar between pairs of seasons. This study also investigated whether woodland dormice Graphiurus murinus positively select or avoid specific microhabitat types or structures, and whether a set of predictor variables related to microhabitat characteristics can explain the presence and rates of visits to specific trapping stations. Trapping was conducted seasonally, over 5 days, between June 2011 and April 2012. A grid of 96 stations (16 rows × 6 lines) was established. Trap stations were set at 10-m intervals. At each station two Sherman traps were placed. The 192 traps were distributed relatively equitably among four height categories (0–0.5 m, 0.51–1 m, 1.01–1.5 m, and 1.51–2.5 m). On average, trapping success was 4.70 ± 4.17 dormice per 100 traps. Dormice were trapped at an average height of 136 ± 64 cm, which was significantly higher than the average height at which traps were set (99 ± 75 cm). Bonferroni Z tests indicated that dormice positively selected areas with high canopy cover and connectivity, possibly to decrease predation risk. Generalized Linear Models showed that trap use and numbers of visits and different animals caught were positively associated with a high arboreal connectivity, hence supporting the hypothesis that woodland dormice may depend on wooden “corridors” for their movements.
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Diet of the yellow mongoose (Cynictis penicillata) in the Albany Thicket Biome of South Africa
- Authors: Bizani, Mfundo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11796 , http://hdl.handle.net/10353/d1019840
- Description: The dietary habits of the yellow mongoose Cynictis penicillata were studied in the Albany Thicket Biome of South Africa (Great Fish River Reserve, Eastern Cape). The diet was investigated through the analysis of 1,056 scats that were sampled over a period of 7 years (2005−2009 and 2011−2012) mainly in three similar sites (Kelarny, Grasslands and Junction 10) that were used by at least three families or groups of yellow mongooses. Scats were collected near latrine sites, labelled and stored in a freezer. In the laboratory, scats were oven dried for a period of 24 hours at 50 C. Diet was determined by identifying undigested food remains in the scats. Hair samples were examined under the compound microscope to identify which mammals were ingested. In the field, both arthropod and small mammal abundance were determined in order to evaluate whether yellow mongooses are opportunistic or specialist feeders. Furthermore, inter-annual (2006–2008) and inter-group/inter-site variations in the diet were assessed. Based on faecal analysis, arthropods were the principal prey, while small mammals acted as supplementary food item. Other food categories like vegetation, reptiles and birds were only ingested or preyed upon infrequently. Intermediate dietary diversity, and low standardised diet breadth indices were obtained for all seasons, as well as for the whole sampling period. The diet overlaps calculated for pairs of seasons were very high and did not differ substantially. However, the diet of the yellow mongoose varied seasonally, yearly and between groups (sites), mostly due to variations in arthropod and small mammal consumption. Food availability displayed an increase in biomass of both small mammals and arthropods in summer and autumn. Results obtained in this study could suggest that the yellow mongoose at the GFRR is insectivorous by preferring to feed on insects (and arthropods in general) when both insects and rodents are abundant. However the fact that its diet varies both seasonally, yearly and locally, as well as the presence of remains of other food categories in the scats, indicates that this species is rather an opportunistic, generalist feeder than an insect specialist.
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Educators’ perceptions of foundation phase mathematics Curriculum Assessment Policy Statements (CAPS)
- Authors: Mnqatu, Fiola Wayne
- Date: 2014
- Subjects: Curriculum evaluation -- South Africa , Curriculum planning -- South Africa , Mathematics -- Study and teaching --South Africa
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: http://hdl.handle.net/10353/1358 , vital:26549 , Curriculum evaluation -- South Africa , Curriculum planning -- South Africa , Mathematics -- Study and teaching --South Africa
- Description: The aim of the study was to investigate the educators’ perceptions of the Foundation Phase Mathematics Curriculum Assessment Policy Statements (CAPS). This was a case study of eight educators in two primary schools based in Cradock in the Eastern Cape Province of South Africa. There were six main findings. First, all participants displayed a good general knowledge of CAPS. They saw CAPS as different from NCS in that the former is content driven as opposed to outcomes driven in the latter. Second, all participants were happy that CAPS specifies what is to be taught grade by grade as opposed to NCS which specified outcomes and required educators to construct the content. Third, a feature which participants liked was the weighting of different components of the subjects taught. This was seen as an important guideline that indicates how much time should be spent on each component. Fourth, participants understood that CAPS is not a new curriculum; it is an amendment of the NCS. As such educators used the same teaching strategies and methods. Fifth, participants had reservations about the CAPS assessment guidelines as they were the same as those of the NCS and felt that the guidelines which require educators to discuss assessment criteria with children were not suitable for children in Foundation Phase. Sixth, participants were happy with the CAPS programme of assessment and workbooks .They felt the programme guides their teaching while the workbooks complement their teaching. It can be concluded that educators, on the whole, held positive perceptions about CAPS. They saw it as explicit about the content that is to be taught, and it has clear guidelines about assessment procedures. For this reason it can be seen as an improvement on the NCS. Given the findings, it can be recommended that further research be carried out on how educators’ understanding of CAPS is translated into practical teaching and learning in the classroom. To improve the delivery of CAPS, the Education Department must devise strategies aimed at educator empowerment activities that will enhance their work performance.
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Effect of irrigation farming potential on commercialization of smallholder farming in the Eastern Cape Province of South Africa
- Authors: Sipoko, Nomava
- Date: 2014
- Subjects: Irrigation farming -- South Africa -- Eastern Cape , Farms, Small -- South Africa -- Eastern Cape , Agriculture -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11218 , http://hdl.handle.net/10353/d1019772 , Irrigation farming -- South Africa -- Eastern Cape , Farms, Small -- South Africa -- Eastern Cape , Agriculture -- Economic aspects
- Description: Enhancement of smallholder production to improve rural livelihood is an important policy goal in developing countries. Research findings indicate that smallholder production can be improved through establishment of new smallholder irrigation schemes, and the rehabilitation of abandoned ones. Smallholder irrigation has a potential to contribute significantly in shifting smallholder farming to commercial farming. Although the roles of irrigating farmers are clearly defined, smallholder farmer’s development results in South Africa have been disappointing. The performance of smallholder irrigation is unsatisfactory. Smallholder irrigation has failed to improve the standard of living and livelihoods of smallholder farmers in South Africa. The majority of farmers are still producing at subsistence level. This study, therefore, aimed to contribute to smallholder irrigation literature in two ways; firstly by evaluating the extent of irrigation participation of smallholder farmers towards commercialization in the study areas. The study also examined the determinants of irrigation participation among smallholder farmers. A sample of 80 households was drawn by random sampling of smallholders in four villages as follows: 40 respondents from Mgxabakazi and Dinizulu villages and 40 respondents from Ncorha flats and Tshatshu. The sample included both irrigators and non-irrigators. Descriptive analysis shows that irrigators had better production and wellbeing than non-irrigators. For the inferential analysis of the data, two models were employed namely, Binary Logistic Regression Model (BRM) and Truncated Regression Model (TRM). The Binary Regression model was used to predict the probability of farmers participating in irrigation schemes. Whether or not a farmer participated in irrigation was introduced as the binary dependent or response variable that could be explained by a range of explanatory or predictor variables such as source of water, land size, ability to sustain business, membership in the scheme, market access, availability of the irrigation system, willingness to irrigate, farming type commercial or subsistence and institutional support services. From these predictor variables, being part of the irrigation, ability to sustain business and market were found to be factors influencing farmer’s decision to participate. The second model required the in-depth investigation of the influence of irrigation participation as reflected by extent of commercialization. In order to do this, the level of commercialization was measured by calculating Household Commercialization Index. Then the truncated regression model (TR) was used to test the factors that affect the level of commercialization for the farmers who are participating in the irrigation schemes.Age, irrigated land, willingness to commercialize and gross value of production were found to exert strong influence on the level of commercialization among farmers participating in irrigation. The study recommends that investments in smallholder irrigation should receive high priority, with emphasis on collective action, promotion of contract farming and strengthening the support services from government and the private sector, and ensuring enhanced access to market to all farmers.
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Effect of pre-slaughter stress of pigs on the levels of cortisol, creatine kinase and their subsequent relationship with pork quality
- Authors: Nzolo, Jama
- Date: 2014
- Subjects: Slaughtering and slaughter-houses , Pork -- Quality , Swine -- Handling , Livestock -- Handling , Creatine kinase
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11837 , http://hdl.handle.net/10353/d1021287 , Slaughtering and slaughter-houses , Pork -- Quality , Swine -- Handling , Livestock -- Handling , Creatine kinase
- Description: The study was conducted to determine the effect of pre-slaughter stress of pigs on the levels of cortisol, creatine kinase (CK) and their subsequent relationship with pork quality. From our knowledge, there is paucity of information on transportation, lairage duration and sex effects on saliva cortisol and its relation with serum cortisol, urine cortisol and other meat quality traits. Stage one of the study assessed the effect of sex and time to slaughter (transport and lairage duration) on the levels of cortisol and CK in crossbred pigs. The second stage of the study evaluated the effect of sex and lairage duration on pork quality. The trials comprised of 60 22-weeks old commercial crossbred pigs [(30 boars vs. 30 gilts) with an average body weight of 76.9kg for gilts and 78.3kg for boars. Thirty pigs (15 Boars vs. 15 Gilts) were slaughtered on arrival after a 120km road journey and the other 30, after travelling the same road and distance, were slaughtered after having been in the lairage for 20 hours. Saliva samples were obtained during three time periods: between 07:00-10:00 on the day before the journey, on arrival at the abattoir and after lairage. Levels of cortisol in serum and urine and CK in serum samples collected at slaughter were determined. The samples (saliva and serum) were centrifuged at 20oC for 10 min at 3550 x g and stored at -20oC in separate vials until analysis. Pork quality was assessed using muscle pH, colour, thawing and cooking losses and Warner-Bratzler Shear Force. Correlations between cortisol levels in saliva, serum and urine and meat quality were assessed. The effect of sex and time to slaughter on saliva cortisol was significant. Statistical analysis showed significant interaction of sex by time to slaughter on serum cortisol. It was only the effect of sex that demonstrated higher (P <0.05) serum creatine kinase levels in gilts. Likewise, urine cortisol was influenced (P <0.05) only by time to slaughter. Saliva cortisol after transportation (r = 0.52) was correlated (P <0.05) with urine cortisol. The study suggests that there are greater responses of the Hypothalamic-pituitary-adrenal axis following time to slaughter (transport and lairage duration) between gilts and boars. This can be used in measuring cortisol in saliva, serum and urine, and serum creatine kinase to determine stress levels in pigs. Besides the lightness (L*) colour value which was significantly lower (P <0.05) in meat from gilts than from boars, the results of this study showed no interaction or individual effect (sex or lairage duration) on pH and other colour measurements. Meat cooking loss was affected (P <0.05) by gender x lairage interaction. Effect of lairage duration (as an individual effect) on the measured meat quality traits was not significant (P <0.05). Correlation analysis showed significant (P <0.05) negative relation between baseline saliva cortisol (r = -0.40) and the pork L* value. Saliva cortisol after lairage duration (r = -0.38 and r = 0.38) was correlated (P <0.05) with pH45 and pork a* value, respectively. Serum cortisol (r = -0.35) was negatively correlated (P <0.05) with pH45. Moreover, there were negative correlations (P <0.05) between saliva cortisol after transportation (r = -0.35), saliva cortisol after lairage duration (r = -0.44), serum cortisol (r = -0.40) and meat cooking loss. The study suggests that cortisol in saliva and serum can be used to determine effect of time to slaughter (transport and lairage duration) on meat quality traits from gilts and boars. Keywords: Boars; gilts; saliva cortisol; serum cortisol; serum creatine kinase; urine cortisol.
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Effects of dietary inclusion of Moringa oleifera leaf meal on growth performance, physico-chemical attributes, oxidative stability and sensory quality of pork
- Authors: Nduku, Xola Pauline
- Date: 2014
- Subjects: Pork -- Quality , Food -- Sensory evaluation , Fatty acids , Moringa , Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11836 , http://hdl.handle.net/10353/d1021281 , Pork -- Quality , Food -- Sensory evaluation , Fatty acids , Moringa , Meat -- Quality
- Description: The objective of the study was to determine growth performance, physico-chemical attributes, oxidative stability and sensory quality of pork from pigs fed one of three dietary treatments, eac containing 0%, 2.5% or 5% (T1, T2 and T3, respectively) Moringa oleifera leaf meal (MOLM). Dietary treatments were formulated to be isonitrogenous and isoenergetic for weaner (6 – 8 weeks) and grower (9 – 13 weeks) phases. Twelve Large White (LW) and 12 Kolbroek (KB) male pigs at 6 weeks of age, initially weighing an average 10 kg, were randomly allocated to one of the dietary treatments, each with four replicates, in individual pens. Feed and water were offered ad libitum. The Longissimus thoracis et lumborum (LTL) muscle of each carcass (n = 24) was sampled for meat quality and fatty acid analyses. Breed differences in measured parameters were observed. In pigs receiving 5% MOLM, the LW had significantly the highest ADFI (P<0.05) than KB pigs. In pigs receiving 2.5% and 5% MOLM, backfat thickness was significantly highest (P<0.05) compared to those receiving 0% MOML. Dietary inclusion of MOLM had no significant effects (P>0.05) on the physico-chemical quality of pork from LW pigs; although it significantly (P<0.05) increased a* and reduced WBSF values in pork from KB pigs. Pork from LW pigs receiving 5% MOLM had significantly increased (P<0.05) n-3 content of the subcutaneous tissue of LW pigs compared to KB, and also when compread to other treatment groups. In both breeds, the composition of PUFA: SFA and n-6: n-3 in the subcutaneous adipose tissue was significantly (P<0.05) lower in T2 and T3 than in T1. The n-3 levels for pork muscle from LW pigs receiving 2.5% and 5% MOLM, and from KB pigs receiving 5% MOLM, were significantly (P<0.05) lower. Inclusions of MOLM significantly (P<0.05) reduced the n-6: n-3 fatty acids in pork from both LW pigs and KB pigs. Consumer scores on sensory attributes (aroma intensity, initial impression of juiciness, first bite, sustained impression of juiciness, muscle fibre and overall tenderness and overall flavor intensity) significantly (P<0.05) increased as the level of MOLM inclusion in the diet increased; and higher scores were observed in fried meat than in boiled for most sensory attributes. It may be concluded that inclusion of MOLM in pig diets up to 5% improved the ADFI, a*, tenderness of pork without adversely affecting the FCR and other physico-chemical quality attributes; and resulted in desired increase in levels of n-3 and reduced the n-6: n-3 fatty acid ratio.
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Effects of oats and vetch cover crops on light organic matter fractions and activities of selected enzymes in an irrigated maize based conservation agriculture system on Alice Jozini Ecotope in the Eastern Cape, South Africa
- Authors: Mukumbareza, Caroline
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11872 , http://hdl.handle.net/10353/d1019815
- Description: Low soil fertility in the Eastern Cape Province (EC) is attributed to poor agricultural management, which reduces organic matter, among other factors. Conservation agriculture (CA), consisting of no-till, soil cover and rotations, is being promoted to improve soil quality and productivity. Soil biological parameters respond to the overall effects of management on the physical and chemical components of soil. This study was conducted to evaluate the effects of oat (Avena sativa) and grazing vetch (Vicia dasycarpa) cover crops on soil biological activity after five years under CA and evaluate light organic matter fractions, MBC and activities of selected enzymes as early indicators of organic matter build up under in no-till maize based CA system. The study was based on soil samples collected from a five year trial with rotations of maize and sole covercrops and two younger trials (4 and 28 months) with oat and grazing vetch bicultures. In the five year old trial, oat and grazing vetch were planted at four fertiliser regimes (i) Fertilizer applied to cover crops and maize (F1), (ii) fertilizer applied to cover crops only (F2), (iii) fertilizer applied to maize only (F3) and (iv) no fertilizer applied (F4)) to give a 2 × 4 factorial plus control laid out in a randomized complete block design (RCBD) with three replications. Fertilizer was applied at 10 kg P ha-1, as a compound (6.7% N; 10% P; 13.3% K) at planting and grazing vetch was inoculated with Rhizobium legunominosarium biovar viciae. Oat was top dressed using limestone ammonium nitrate (LAN – 28% N) at 7 weeks after planting (WAP) to make a total of 45 kg N ha-1. Three weeks after termination of the cover crops, all plots were split in half and maize was planted and fertilizer applied at 0 and 60 N kg ha-1. A third of the N was applied at planting (6.7% N; 10% P; 13.3% K). In the biculture trials, the treatments were 90% oat + 10% vetch, 70% oat + 30% vetch, 50% oat+ 50% vetch, 100% vetch and 100% oat and laid out in a RCBD with three replicates. Only basal fertilizer was applied to the cover crop at planting at 13.34 kg N ha-1, 20 kg P ha-1 and 26.66 kg K ha-1 using 2:3:4 (30 + 0.5% Zn) compound fertiliser. After cover crop termination, SC701 maize variety was planted, and fertilised at 60 kg N ha-1 with a third of the N applied as a basal. In the five year old trial, oat and vetch gave significantly (P < 0.05) higher MBC and activities of all soil enzymes measured than the weedy fallow at 0-5 and 5-20 cm depths. Fertilization of cover crop (F2) and maize (F3) gave similar MBC. The F4 in cover crops gave similar dehydrogenase activity with F3 under weedy fallow and that for vetch rotation was the same for F3 in oat. The F4 for grazing vetch had similar β-glucosidase activity as F1 and similar urease activity as F1, F2 and F3 of oat rotations. Acid and alkaline activity in F1 had similar results to F2. In the younger trials, biculture treatments did not improve total C, and N when compared with the weedy fallow. Dehydrogenase, β-glucosidase, arylsulphatase and alkaline phosphatase activities were higher in the 28 month trial compared to the 4 month one while urease was higher in the 4-month old trial. Treatments with more than 50% oat content had higher acid phosphatase activity in the 4- than 28 month old trial. Effects of cover crop, as the main factor, was significant in all enzymes (P < 0.05), with 70% oat + 30% vetch treatment having the highest dehydrogenase and arylsulphatase while for alkaline phosphatase it had similar results to 90% oat + 10% vetch. For β-glucosidase and urease, effects of cover crop as the main factor were also significant with sole vetch giving the highest activity for both enzymes. Acid phosphatase activity was highest in sole oat. Particulate OM was highest in the 100% oat treatment and declined with decrease in the proportion of oat in the biculture. The 50% oat + 50% vetch treatment had similar POM to the 70% oat +30% vetch in the 4 month old trial and to the 90% oat + 10% vetch in the 28 months old trial in the 0-5 cm depth (P < 0.05). In the 5-20 cm depth, the 70% oat +30% vetch treatment had similar POM to the 90% oat + 10% vetch in the 28 month old trial. The 70% oat+30% vetch had greatest WSC and MBC followed by the 90% oat +10% vetch, with the 50% oat + 50% vetch being similar to 100% vetch and 100% oat (MBC only). The 28 months old trial had greater POM and WSC than the 4 months trial. The findings of this study imply that the use of grazing vetch and fertilization of cover crops only improves soil biological activity, represented by MBC and enzyme activities, after 5 years of maize-cover crop rotations in low input conservation agriculture system. Bicultures, particularly the 70% oat + 30% vetch, work better than their sole crops in improving organic matter fractions, MBC and enzyme activities and that POM, WSC, MBC, enzyme activities are useful early indicators of soil organic matter build-up of CA systems.
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Electing high-order modes in solid state laser resonators
- Authors: Iheanetu, Kelachukwu
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: http://hdl.handle.net/10353/995 , vital:26516
- Description: The first chapter considered the fundamental processes of laser operation: photon absorption, spontaneous and stimulated emissions. These processes are considered when designing a laser gain medium. A four-level laser scheme was also illustrated. Then, the basic components and operating principle of a simple laser system was presented using a diode end-pumped Nd:YAG solid state laser resonator. The second chapter considered laser light as light rays propagating in the resonator and extensively discussed the oscillating field in the laser resonators. It examined the characteristics of the fundamental Gaussian mode and the same theory was applied to higher-order modes. Chapter three started with an introduction to beam shaping and proceeded to present a review of some intra-cavity beam shaping techniques, the use of; graded phase mirrors, difractive elements { binary phase elements and spiral phase elements. Also, a brief discussion was given on the concept of conventional holography and digital holography. The phase-only spatial light modulator (SLM) was presented, which by default is used to perform (only) phase modulation of optical fields and how it can be use to perform amplitude modulation also. Finally, a detailed discussion of the digital laser which uses the intracavity SLM as a mode selection element was presented, since it was the technique used in the experiment. The elegance of dynamic on-demand mode selection that required only a change of the grey-scale hologram on the SLM was one quality that was exploited in using the digital laser. The next two chapters presented the experiments and results. The concept of the digital laser was first used in the experiment in chapter four, to assemble a stable diode endpumped Nd:YAG solid state laser resonator. Basically, the cavity was of hemispherical configuration using an intra-cavity SLM (virtual concave mirror) as a back re ector and a at mirror output coupler. A virtual concave mirror was achieve on the SLM by using phase modulation to generate the hologram of a lens, which when displayed on the SLM made it to mimic a concave mirror. Then the next phase was using symmetric Laguerre-Gaussian mode function, of zero azimuthal order to generate digital holograms that correspond to amplitude absorbing concentric rings. These holograms, combined with the hologram that iv mimics a concave mirror were used on the SLM to perform high-order Laguerre-Gaussian modes selection in the cavity. The fifth chapter presented the results of the mode selection and considered the purity of the beam at the output coupler by comparing measured modal properties with the theoretical prediction. The outcome confirmed that the modes were of high purity and quality which further implied that the cavity was indeed selecting single pure high-order modes. The results also demonstrated that forcing the cavity to oscillate at higher-order modes (p = 3) extracted 74% more power from the gain medium compared to the fundamental mode (p = 0), but this extra power is only accessible beyond a critical pump input power of 38.8 W. Laser brightness describes the potential of a laser beam to achieve high intensities while still maintaining a large Rayleigh range. It is a property that is dependent on beam power and its quality factor. To achieve high brightness one needs to generate a beam that extracts maximum power from the gain with good beam quality. Building on the experiments demonstrated in this study, one can make the correct choices of output coupler's re ectivity, the laser gain medium's length and doping concentration and the pump mode overlap for a particular mode to further enhance energy extraction from the cavity, and then using well known extra-cavity techniques to improve the output beams quality factor by transforming the high-order mode back to the fundamental mode. This will electively achieve higher laser brightness.
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Electronic Governance (E-Governance) as a Public Sector Management Tool for service provision in Buffalo City Metropolitan Municipality
- Authors: Moyo, Thokozani P
- Date: 2014
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:11714 , http://hdl.handle.net/10353/d1015268
- Description: The study explores the use of Electronic governance (E-governance) as a Public Sector management tool for service provision in the Buffalo City Metropolitan Municipality. The main research question being pursued sought to find out the extent to which E-governance can be an effective tool for public sector management and service provision in the municipality. The study used both quantitative data (obtained through questionnaire survey) and qualitative data (through in-depth responses from municipality employees). The findings of the study seem to indicate that electronic governance is being utilised by a lesser percentage of citizens although it seems to be slowly gaining popularity with the highly educated and younger members of the public. Some members of the communities were still adamant to using online resources for different reasons. The study also reveals some challenges such as poverty, inequality and illiteracy as some of the hindrances to e-government. However, there is a degree of success of electronic governance in the municipality as evidenced by the percentage of the population now using the online transactions. A lot needs to be done in order to view e-governance as a true success in this municipality of Buffalo City Metropolitan if services are to be delivered effectively and efficiently to the people. It is therefore strongly recommended that there is a need to put in place good educational measures to ensure that the citizens are informed about various ways of doing online transactions with the municipality other than physically going there.
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Energy and sustainable development: the case of Dewedzo rural community in Zimbabwe
- Authors: Mbulayi, Shingirai P
- Date: 2014
- Subjects: Sustainable development -- Zimbabwe , Renewable energy sources -- Zimbabwe , Power resources -- Zimbabwe , Energy consumption -- Zimbabwe
- Language: English
- Type: Thesis , Masters , M Soc Sc (Dev)
- Identifier: http://hdl.handle.net/10353/866 , vital:26504 , Sustainable development -- Zimbabwe , Renewable energy sources -- Zimbabwe , Power resources -- Zimbabwe , Energy consumption -- Zimbabwe
- Description: Energy poverty is a concept that has gained significance quite recently. Its significance has been prompted by the realization that without sustainable modern energy alternatives for the rural poor, prospects for rural transformation remains low. The recognition of modern energy as one of the missing link in rural transformation comes amid the growing concern about the negative effects of relying on traditional energy services and the increasing forecasts that most developing countries are likely to miss their MDG targets by 2015. Drawing on the Modernization and the Sustainable Development Approach, this study concluded that improving the quantity and quality of energy services consumed by the rural poor can counteract rural underdevelopment and enhance rural social and economic transformation in Dewedzo. The study confirmed that energy poor households are prone to various social, economic and environmental detriments such as poor health, hunger, malnutrition, poor education and missed socio economic opportunities. By addressing rural people‟s energy needs, more nexus can be injected into rural productivity and the economic social outputs of this process can in turn increase the pace at which MDGs can be achieved.
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Enhancement of the usability of SOA services for novice users
- Authors: Yalezo, Sabelo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: http://hdl.handle.net/10353/822 , vital:26500
- Description: Recently, the automation of service integration has provided a significant advantage in delivering services to novice users. This art of integrating various services is known as Service Composition and its main purpose is to simplify the development process for web applications and facilitates reuse of services. It is one of the paradigms that enables services to end-users (i.e.service provisioning) through the outsourcing of web contents and it requires users to share and reuse services in more collaborative ways. Most service composers are effective at enabling integration of web contents, but they do not enable universal access across different groups of users. This is because, the currently existing content aggregators require complex interactions in order to create web applications (e.g., Web Service Business Process Execution Language (WS-BPEL)) as a result not all users are able to use such web tools. This trend demands changes in the web tools that end-users use to gain and share information, hence this research uses Mashups as a service composition technique to allow novice users to integrate publicly available Service Oriented Architecture (SOA) services, where there is a minimal active web application development. Mashups being the platforms that integrate disparate web Application Programming Interfaces (APIs) to create user defined web applications; presents a great opportunity for service provisioning. However, their usability for novice users remains invalidated since Mashup tools are not easy to use they require basic programming skills which makes the process of designing and creating Mashups difficult. This is because Mashup tools access heterogeneous web contents using public web APIs and the process of integrating them become complex since web APIs are tailored by different vendors. Moreover, the design of Mashup editors is unnecessary complex; as a result, users do not know where to start when creating Mashups. This research address the gap between Mashup tools and usability by the designing and implementing a semantically enriched Mashup tool to discover, annotate and compose APIs to improve the utilization of SOA services by novice users. The researchers conducted an analysis of the already existing Mashup tools to identify challenges and weaknesses experienced by novice Mashup users. The findings from the requirement analysis formulated the system usability requirements that informed the design and implementation of the proposed Mashup tool. The proposed architecture addressed three layers: composition, annotation and discovery. The researchers developed a simple Mashup tool referred to as soa-Services Provisioner (SerPro) that allowed novice users to create web application flexibly. Its usability and effectiveness was validated. The proposed Mashup tool enhanced the usability of SOA services, since data analysis and results showed that it was usable to novice users by scoring a System Usability Scale (SUS) score of 72.08. Furthermore, this research discusses the research limitations and future work for further improvements.
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Enterococcus pathotypes as reservoirs of antibiotic resistance determinants in the Kat River and Fort Beaufort abstraction waters
- Authors: Ntloko, Phindiwe
- Date: 2014
- Subjects: Enterococcus , Drug resistance
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11290 , http://hdl.handle.net/10353/d1019821 , Enterococcus , Drug resistance
- Description: In this study, 400 presumptive Enterococcus isolates previously recovered from Kat River and Fort Beaufort Abstraction water dam were subjected to molecular confirmation and pathotyping. Two hundred and seventy-four (68%) of these isolates were confirmed to be enterococci species. Confirmations studies were polymerase chain reaction (PCR) based, using enterococci specific primers targeting the tuf gene. The confirmed enterococci isolates were further differentiated into their pathotypes, the targets of which were: E. faecalis, E. avium, E. hirae, E. casseliflavarus and E. gallinarum using well documented species specific primer sequences. E. faecalis accounted for 20% of the isolates, followed by E. avium (16%), E. hirae (13%), E. casseliflavarus (5%) and E. gallinarum (3%). Furthermore, all the confirmed isolates were analysed for antibiotic susceptibilities using a panel of nine different antibiotics, namely vancomycin, linezolid, ciprofloxacin, ampicillin, gentamicin, chloramphenicol, tetracycline, erythromycin, penicillin, and those that were resistant were assayed for the presence of relevant antibiotic resistance genes. All the 274 isolates were found to harbour vanA resistance gene confirming their phenotypic resistance to the vancomycin. Similarly, 60% (109/180) of the isolates showed phenotypic resistance to erythromycin which was further confirmed by the presence of ermA genes in these isolates. The presence of antibiotic resistant bacteria in surface waters poses a risk to public health.
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Ethanol production from lignocellulosic sugarcane leaves and tops
- Authors: Dodo, Charlie Marembu
- Date: 2014
- Subjects: Biomass energy , Ethanol as fuel , Lignocellulose
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11347 , http://hdl.handle.net/10353/d1019839 , Biomass energy , Ethanol as fuel , Lignocellulose
- Description: Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.
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Evaluating the beneficiary management process in housing delivery: a case study of Buffalo City Metropolitan Municipality in the Eastern Cape (2013)
- Authors: Matiwane, T
- Date: 2014
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:11685 , http://hdl.handle.net/10353/d1013565
- Description: The study critically analysed the problems encountered in the housing delivery in the Buffalo City Metropolitan Municipality for the 2013 period. The purpose is to look at the factors that affect housing delivery in the area, focusing more especially at the management of the beneficiaries and the process thereof. Buffalo City Metropolitan Municipality is not immune to the housing problem hence the study was initiated. Respondents were selected from among others the housing beneficiary and the predominantly the staff of Buffalo City Metropolitan Municipality to respond to the questionnaires related to the beneficiary management. Permission was sought from the Municipality to conduct the research, after which the questionnaires were distributed to all sampled respondents accordingly in line with the objectives of the research. The researcher distributed the questionnaires and allowed a period of three weeks for the respondents to respond to them, after which the researcher collected all the questionnaires. The study revealed the great understanding of the housing delivery process by the housing recipients. Inclusive of the administrators, i.e. Buffalo City Metropolitan Municipality staff members, are fully aware of the expectations from the recipients and the process. The findings further indicates that there are serious challenges facing housing delivery in the province and the country at large. Hence the beneficiaries could not get their houses on time and the housing projects did not get completed within the scheduled period, this ends up delaying the delivery process.
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Evaluating the implementation of the principles of good governance in Zimbabwe local government system : a case of Marondera local municipality
- Authors: Muswaka, Phyllis
- Date: 2014
- Subjects: Local government -- Zimbabwe Public administration -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/13068 , vital:39453
- Description: Participatory budgeting currently occupies centre stage in Public and Municipal financial management Acts. The principle of participatory budgeting ushers in a broader public forum in which crucial principles in Public financial management such as accountability and transparency are observed, thereby automatically ensuring effective governance. The efficacy of participatory budgeting is to improve service delivery through opening up structures that will combat the spread of mal administrative practices such as corruption and financial fraud whilst enhancing democratic participation and upholding the rule of law by fostering transparency and accountability and making the governments more responsive to the needs of the people. The main objective of this study is to explore the pernicious effects of having limited citizen participation in Public finance management. It seeks to examine whether the poor service delivery by local municipalities can be attributed to the lack of effective citizen participation. This will be done through assessing whether the seeds of participatory budgeting have led to the fruits of efficient and effective service delivery in the public sector both in theory and in practice at Nkonkobe local municipality. It has been discovered that the inability to provide effective service delivery is a complex challenge facing many municipalities in South Africa, and although such a situation has been co-determined by many other factors including financial restraints, the root cause of service delivery incapability’s can be traced back to weather the citizens are actually participating in the management of public finances through participatory budgeting or not. More often than not, the failure to accommodate the citizens in local government affairs has been the spark that has been responsible for setting alight strikes and service delivery protest marches in most of South Africa’s Provinces. However, due to this, this study aims to reveal that participatory budgeting is an ambitious issue that requires local authorities to focus on in order to improve service delivery through embracing active citizen participation. Recommendations as well as consequences of lack of citizen participation in the budget process were thereby highlighted.
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Evaluation of some wastewater treatment facilities in Chris Hani and Amathole district municipalities as potential sources of Escherichia coli in the environment
- Authors: Mazwi, Sinazo Nomathamsanqa
- Date: 2014
- Subjects: Escherichia coli -- South Africa -- Eastern Cape , Water -- Purification
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11285 , http://hdl.handle.net/10353/d1019804 , Escherichia coli -- South Africa -- Eastern Cape , Water -- Purification
- Description: Access to clean and safe water is essential for the survival of human beings. Pollution of freshwater sources constitutes a major problem hindering access to safe water for drinking and other domestic uses. Wastewater effluent discharges often impact the microbiological qualities of surface waters with its attendant health and environmental problems. This study evaluated the microbiological qualities of the discharged effluents of four selected wastewater treatment plants in Amathole and Chris Hani District Municipalities of the Eastern Cape Province over a twelve-month sampling period. Microbiological analysis (faecal coliform, Escherichia coli and Escherichia coli O157:H7) was done using standard methods and polymerase chain reaction method was used to confirm identities ofbacterial isolates. Presumptive bacteria counts ranged as follows: faecal coliforms 0 to 1.6 × 103 CFU/100 ml, E. coli 0 to 1.4 × 103 CFU/100 ml and E. coli O157:H7 0 to 9.6 × 102 CFU/100 ml. Forty eight percent (305/626) of the presumptive E. coli isolates were confirmed using species-specific uidA gene which code for β-glucuronidase enzyme in E. coli. Antibiotic susceptibility profile of the isolate using a panel of 10 antibiotics shows 100% (150/150) resistance to antibiotics rifampicin and penicillin G while 49.3% (74/150) of the isolates and 46.7% (70/150) were susceptible to streptomycin and cefotaxime respectively. Multiple antibiotic resistance phenotypes (MARP) of the isolates showed resistance to two or more test antibiotics while the calculated multiple antibiotic resistance index (MARI) for the tested isolated is 0.49. The detection of potentially pathogenic E. coli in the final effluents suggestspotential danger to the receiving water bodies where the effluents are discharge. The high MARI valued obtained in this study indicates that the isolates are form environment where the tested antibiotics are being used and may further lead to the spread of multiple antibiotics resistance among other pathogens that may be present in the same environment.
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Evaluation of the efficacy of Carpobrotus edulis (L.) bolus leaf as a traditional treatment for the management of HIV/AIDS
- Authors: Omoruyi, Beauty Etinosa
- Date: 2014
- Subjects: AIDS (Disease) -- Treatment -- South Africa -- Eastern Cape , Phytochemicals -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Carpobrotus
- Language: English
- Type: Thesis , Doctoral , PhD (Biochemistry)
- Identifier: http://hdl.handle.net/10353/744 , vital:26493 , AIDS (Disease) -- Treatment -- South Africa -- Eastern Cape , Phytochemicals -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Carpobrotus
- Description: The human immunodeficiency virus (HIV) is one of the most common and dreaded diseases of the 21th century. Today, the disease is still spreading with increasing incidence. “Since the beginning of the epidemic, almost 75 million people have been infected with the HIV virus and about 36 million people have died of HIV. Globally, 35.3 million [32.2–38.8 million] people were living with HIV at the end of 2012” (http://www.who.int/gho/hiv/en/). Several studies have been conducted on herbs under a multitude of ethnobotanical grounds. The use of medicinal plants for the management of HIV has become a common practice especially, in the Eastern Cape Province of South Africa (Wilfred Otang Mbeng, 2013 PhD thesis, UFH). At the beginning of this programme, an ethnomedicinal survey of plants used for the management of HIV infection was carried out in targeted areas of the Province and information on the names of plants, the parts and the methods of preparation were collected. The survey revealed that 18 species representing 12 families were found to be commonly used for the management of HIV, as well as other opportunistic diseases such as tuberculosis, diabetes mellitus, sores, high blood pressure, etc. Carpobrotus edulis was selected for this research because it was the most frequently used in the Province. The foliar micro morphological contents of the plant, its phytochemical and antioxidant activity, in vitro antimicrobial activity, inhibitory effect against HIV-1 protease and reverse transcriptase, mechanisms of action and cytotoxicity were investigated. In terms of the foliar micro morphological contents in plants, an electron microscopy scanning (SEM) was completed. Investigation revealed that both glandular tricomes and calcium oxalate crystals (CaOX) were observed. Consequently, it is hypothesized that the bioactive therapeutic compounds secreted by C. edulis may be produced in the glandular trichomes. An investigation of phytochemical content of the plant extracts (C. edulis) was completed using four solvent extracts (hexane, acetone, ethanol and water). Results of the phytochemical analysis showed that proanthocyanidins (86.9 ± 0.005%) where highest in the aqueous extract with phenolics at 55.7 ± 0.404% in acetone extract, tannin at 48.9 ± 0.28% in ethanol extract, while the hexane extract had the highest levels of flavonoids (0.12 ± 0.05%) and flavonols (0.12 ± 0.05%). Antioxidant studies of the various extracts revealed that aqueous and ethanol extracts were found to be the best solvents for antioxidant activity in C. edulis leaves. GC-MS analysis of the essential oil from C. edulis leaves revealed that the essential oil contained at least 28 compounds. These included, in order of abundance: Oxygenated monoterpenes (36.61%); fatty acids esters (19.25%); oxygenated diterpenes (19.24%); monoterpenes (10.6%); sesquiterpenes (3.58%); and diterpenes (1.43%). Similarly, a GC-MS analysis of the crude hexane, acetone and ethanol extracts from C. edulis leaves identified a total of 59 compounds. Of the 59 compounds, 12 major phyto-metabolites that are active against infectious diseases were identified. To comfirm the potential use of C. edulis to treat infectious disease, antifungal activity of the crude essential oil extract and the four solvent extracts were tested against Candida albicans, Candida krusei, Candida glabrata, Candida rugosa and Cryptococcus neoformans strains. The essential oil extract was found to be the most active against all the fungal strains tested and performed better than the four extracts used various solvents used to extract (hexane, acetone, ethanol and water) the C. edulis leaves were tested for antibacterial and anti HIV-1 reverse transcriptase (RT) activity. The results indicated that both gram-positive and gram-negative isolates were inhibited by the extracts (hexane, acetone and ethanol) but antimicrobial activity was observed for the water extract. The lowest minimum inhibitory concentration values were obtained for the ethanol extract, followed by acetone and hexane extracts. No inhibition of HIV-1 reverse transcriptase was observed for any of the leaf extracts, even up to concentrations of 16 mg/ml. The potential inhibitory activities of the various solvent extracts against HIV-1 protease were evaluated at four different concentrations (16, 1.6, 0.16 and 0.016 mg/ml). Results indicated that the water extract showed almost 100% inhibition of HIV-1 protease activity, with an IC50 of 0.86 mg/ml leaf extract. Other solvent extracts (hexane, acetone and ethanol) however, did not show any inhibition activity above that observed for the DMSO control. The metabolic components in the water extract were subjected to LC-MS/MS analysis, which identified at least 91 compounds present in the water extract. Further studies involving the molecular modelling need to be carried out to confirm the inhibitory potential of these compounds. The cytotoxicity of the water extract of C. edulis leaves was also screened using human Chang liver cells at concentrations ranging bewteen 0.005 mg/ml and 1 mg/ml. Results indicated that the water extracts were not toxic. In conclusion the results from this study support the use of water extracts of C. edulis leaves by traditional healers to treat HIV infections and have identified possible mechanisms of action of the water extracts of C. edulis.
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