Performance comparison of the residential types of air source heat pump water heaters in South Africa due to the refrigerant thermo-physical properties
- Authors: Sikhonza, Mandlenkosi
- Date: 2018
- Subjects: Heat pumps Water heaters
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9275 , vital:34317
- Description: Globally hot water heating contributes enormously to the increase in energy consumption in the residential sector. Coal being a fossil fuel and non-renewable source of energy remains the major source used for electricity generation. The burning of coal is the primary cause of CO2 emission into the environment which causes climate change and global warming. Energy efficiency and renewable energy technologies were employed as one of the alternative ways of reducing global warming. In most residential areas in South Africa, the water heating generates 30 -50percent of the monthly electricity bill (Zhang and Huan, 2013). In this light, residential load management (RLM) is a significant part of the load management programme of Eskom’s overall demand side management strategy. Through RLM, the electricity load is being transferred from peak times to off times by switching the geysers during peak hours because geysers consume more electricity and contribute significantly to the national grid constraint problem (Eskom, 2012).
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Performance evaluation of an off-grid building integrated photovoltaic system in Alice, Eastern Cape province, South Africa
- Authors: Buma, Carine Lethem
- Date: 2018
- Subjects: Building-integrated photovoltaic systems Buildings -- Energy conservation Performance -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13227 , vital:39623
- Description: The constant increase in the global demand for energy and the current crisis on global warming and climate change has prompted a dying quest for clean, sustainable and reliable sources of energy. Amongst numerous renewable energy technologies, harnessing energy from the sun is the most viable way of guaranteeing a clean and sustainable supply of energy. Also, photovoltaic energy is one of the ways of using energy from the sun, where sunlight is converted to electricity using photovoltaic panels. Furthermore, the integration of photovoltaic modules into buildings is one of the most elegant innovations of this technology, as it plays the dual role of supplying energy to the building as well as protecting the building from outdoor weather conditions. Moreover, operating off the grid offers the possibility of energy access to locations far off from the grid and individuals willing to gain some degree of energy independence. Evaluating the performance of existing off grid and/or building integrated photovoltaic systems is the key to guaranteeing sustainable development and advancement in the technology. Thus, the aim of this work was to evaluate the performance of an off-grid building integrated photovoltaic system that was installed at the Fort Hare Institute of Technology. This entailed performing an in-depth characterisation of the solar resource at this location, evaluating the performance of the modules under outdoor weather conditions and also evaluating the performance of the balance of system (BOS) components. The system was monitored for a period of nine months (between February and October 2017). A data acquisition system was designed for measuring and recording both electrical system parameters and meteorological parameters affecting the performance of the system. These meteorological parameters include; solar irradiance, ambient temperature, cell temperature, relative humidity, wind speed and direction. A detailed characterisation of the solar resource at this location was carried out. It was observed that the solar declination angle varied from -23.5o on the summer solstice to 23.5o on the winter solstice. Also, the solar altitude angle (at solar noon) which is a complementary angle to the zenith angle varied from 33.7o in June to 80.65o in December. During the summer months, longer day lengths were experienced because the sun traversed the sky over a longer time, rising south of east and setting south of west. Whereas, in the winter months, the path length of the sun was shorter, with the sun rising north of east and setting north of west, hence, shorter day lengths. The solar radiation incident on a 25o north facing solar collector was found to be in three components; beam, diffuse and reflected. The beam component was higher in summer whereas the diffuse component was higher in winter due to an increase in the air mass ratio. However, the total daily average radiation was highest in January (7.12 peak sun hours) and least in June (3.04 peak sun hours). Finally, a comparison between the calculated and measured values of solar radiation showed just a 1.1percent difference over the year with disparities being in the individual months.m The influence of outdoor weather conditions on the performance of the system was also evaluated. Operating temperatures were noticed to have a great impact on the output voltage and power of the PV array. Significant correlations existed between various meteorological parameters. Also, a multiple linear regression model was developed to ascertain the dependence of module temperature on solar irradiance, ambient temperature, relative humidity, wind speed and wind direction. The coefficient of determination for the model was 0.928, showing a strong relationship between cell temperature and the chosen predictors. Also, the six thermocouples installed at various locations of the PV array revealed variations in the operating temperatures of the modules. The modules on the east side of the array recorded relatively lower temperatures because of the ceiling that had been removed beneath one of the modules on this side of the array, which permitted the free flow of air. Furthermore, I-V measurements conducted on various strings of the array revealed so many steps (hotspots), indicative of module (or cell) mismatch on almost all the cell strings.
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Pollution potential of on-site dry sanitation systems associated with the Mzimvubu Water Project, Eastern Cape, South Africa
- Authors: Mamera, Matthew
- Date: 2018
- Subjects: Water resources development Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6038 , vital:29485
- Description: Protecting the environment requires tools that can be used to monitor environmental conditions for proper sustainable management of water resources. The Mzimvubu River is the largest undeveloped river, in the poorest region of South Africa. The South African government announced plans to construct two large storage dams (Ntabelanga and Laleni) in the Tsitsa River, one of the largest tributaries to the Mzimvubu River. The dams and associated infrastructure is termed the Mzimvubu Water Project (MWP). In developing countries like South Africa, several households use pit latrines. Moreover, many people also rely upon untreated groundwater supplies for their drinking water. The shared utilization of both pit latrines and groundwater resources, can lead to human and ecological health risks from microbial and chemical pollutants. These threats can be accelerated due to a permanent rise in the water table associated with dam constructions. Four hillslope sites with pit latrines (MT1, MT2, MT3 and MT4) above 1st order tributaries to the Tsitsa River, in the vicinity of the proposed MWP were chosen for this study. The soils were described and classified at selected locations below the pit latrine and above the tributary. Undisturbed core samples were from representative soil horizons on which hydraulic properties were determined in the laboratory. Samples were also collected to determine the feacal coliform and other bacterial concentrations during a winter and summer period. Mechanistic modelling with Hydrus 2D for a 121 day period was conducted to determine the risk of pollution to surface and groundwater from the various sites. Apedal soils of the Clovelly form dominated upper slopes of MT1 and the lower slopes of MT2. A Clovelly form is hydropedologically termed a recharge soil, as morphological indicators of saturation are absent. Hydromorphic soil properties were observed in the sub-surface B horizons of a Tukulu form in MT1-3 and MT4. High clay contents and strong structure soils of the Sepane form were dominant in MT3. The soils of MT1 and MT2 are relatively sandy with slightly higher hydraulic conductivities compared to MT3 and MT4. In general higher measured faecal coliform concentrations were higher in winter as compared to summer seasons but in most sites both winter and summer seasons had counts < 1 CFU/g. The highest concentrations of total bacteria (9 x 106 CFU/ g soil) was observed in MT3-1. Other sites with potential pollution include MT3-3, with a count above 4 x 104 CFU /g soil in winter and MT1-1 with a count above 2.2 X 104 CFU /g soil in summer. In most of the sites, the E. coli bacteria detections were low (< 1 CFU/g) during both seasons. The highest value in summer of 1.8 x 102 CFU/g was observed in MT3-3 which increased from 1.2 x102 CFU/g in winter. As the soil water flow rate increase the mobility of bacteria increase as well. Hydrus simulations showed that surface water resources are threatened by pollution from MT3 and MT4 due to the prominence of lateral flow. Groundwater pollution is more likely to occur on MT1 and MT2 as the soils are freely drained. Future work should focus on the more direct measurements and modelling of the migration of bacterial pollutants from pit latrines to various water resources.
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Preparation, characterization and in vitro analysis of polyamidoamine drug conjugates containing ferrocene and platinum analogues
- Authors: Mugogodi, Ansley
- Date: 2018
- Subjects: Ferrocene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10145 , vital:35360
- Description: Polyamidoamine drug conjugates were prepared from analogues of ferrocene and platinum. Standard reaction procedures were followed in the synthesis of platinum and ferrocene analogues. Michael addition reaction of amines to the activated double bonds of methylenebisacrylamide was applied for preparation of the water soluble polyamidoamine carriers onto which drug analogues were attached. The drug release studies of the conjugates were evaluated at different pH environments. The results obtained from drug release studies showed that rate of drug release was variable depending on the conjugate and pH environment. Mathematical drug release models by Korsmeyer-Peppas were used to determine the drug release characteristics of the ferrocene and platinum based drugs from polyamidoamine drug conjugates. Cytotoxicity potential of the analogues and polyamidoamine drug conjugates was tested on selected cell lines. Cisplatin was used as the standard for comparison of the IC50 values obtained for the compounds tested for cytotoxicity activity. The results from six polymer drug conjugates tested for cytotoxicity activity showed that conjugation of analogues to polyamidoamine carrier enhanced the activity of the analogues in some of the polyamidoamine drug conjugates. Various techniques such as Fourier Transform Infrared (FTIR) spectroscopy, Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX) spectroscopy were employed for the characterization of the ferrocene and platinum analogues, polyamidoamine carriers and drug conjugates.
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Productivity and profitability of different maize varieties and cropping systems used in the smallholder sector of the Eastern Cape Province of South Africa : implication on food security
- Authors: Kambanje, Ardinesh
- Date: 2018
- Subjects: Crop yields Crops and climate Cropping systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6237 , vital:29528
- Description: Low maize yields in the midst of abundant arable land, favourable climatic conditions, input and financial support programs, plagues smallholder maize farming in Eastern Cape Province. These scenarios have led the province to be a net importer of maize. In essence, low production may signify a mis-match between maize varieties being promoted amongst smallholder farmers and their farming system. Thus, the main objective of the study was to investigate the productivity and profitability of different maize varieties and cropping system under smallholder agriculture in selected villages of the Eastern Cape Province of South Africa as well as, the implications posed on the household food security. The study sought to assess: (i) the productivity of different maize varieties and cropping systems, (ii) the effect of GM maize adoption on food security among smallholder farmers, (iii) the profitability of GM, conventional hybrids and OPV maize varieties produced by farmers under different agro-ecological conditions and (iv) the impact of different maize varieties and cropping systems on food security in the smallholder agriculture. A cross sectional quantitative-based survey study was carried out to obtain information from a total of 650 small holder farmers. The study was conducted in three local municipalities in Oliver Reginald (OR) Tambo District Municipality of the Eastern Cape Province of South Africa. Descriptive statistics, partial factor productivity, gross margin analysis, household food insecurity access score (HFIAS), ordinal logistic and linear regression were the analytical techniques used in establishing correlations among variables. Results obtained from the survey indicated that under mono-cropping system, Genetically Modified (GM) maize variety was highly productive with an average yield of 1.9 t/ha whilst, improved OPV maize variety was productive (with an average yield of 1.6 t/ha) under mixed cropping system. Furthermore, GM maize (GM = -R418.10), and landrace (GM = -R1 140.29) maize varieties had negative gross margins whilst, conventional hybrids (GM = R5 181.21) and improved OPV (GM = R1 457.41) were profitable. There was a significant and negative correlation between use of GM maize variety and reduction of household food insecurity. GM maize varieties, improved OPV, white maize, white as well as yellow GM maize varieties had a significant impact in reducing household food insecurity; whilst using more than one variety of maize (landraces and GMO) positively influenced household food insecurity. In light of these research findings, it is recommended that, there is need to address household food security by growing improved OPVs under a mixed cropping system and GM maize under monocropping system.
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Regional and community food systems for rural households :|bthe case of maize in Mqanduli, Eastern Cape Province, South Africa
- Authors: Qangule, Mondli
- Date: 2018
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Agricultural systems -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10232 , vital:35383
- Description: Smallholder farmers have been growing food in their communities, but some are still food insecure. Therefore, appropriate food systems are very important for smallholder farmers’ self-reliance as well as food and nutrition security. The study focuses only on community and regional maize food systems for rural households. The main aim of this study was to investigate the regional and community food systems for smallholder maize farmers in Mqanduli. The objectives of the study were to profile smallholder maize farmers, describing the existing maize food systems and patterns in Mqanduli and also to determine factors that influence farmers’ participation in local or regional markets. Availability or convenient sampling and random sampling techniques were used to collect primary data from smallholder maize farmers. Descriptive statistics was used to profile smallholder farmers, as well as, in describing the existing maize food systems at Mqanduli. The binary logistic regression model was used to analyse the variables that had influenced the smallholder famers’ participation in markets. Descriptive results revealed that, smallholder maize farmers in Mqanduli are characterised by high participation in both local and regional markets. Moreover, they utilized both community and regional food systems. Logistic regression results indicated that, out of 11 variables included in the analysis as factors influencing farmers’ participation, 6 of them (age, level of education, market information, distance, access to credit and extension visit) were found to be significant and 5 (gender, amount of land, transport availability etc) were not significant. However, access to credit and distance were found to be the most significant variables, showing a positive relationship to smallholder maize producer`s market participation. Therefore, it was recommended that, there must be more investment in research by government and policy makers when it comes to food systems especially in rural areas, to enhance smallholders’ livelihood. More access to credit is also needed by farmers in order to be able to market their produces.
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Rose-scented geranium oil yield and composition as affected by leaf age, herbage drying and paclobutrazol
- Authors: Dyafta, Viwe
- Date: 2018
- Subjects: Essences and essential oils Rose geranium oil
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10747 , vital:35733
- Description: Essential oil of rose scented-geranium is highly versatile and this makes it a very important essential oil in aromatherapy, medicine and cosmetics as well as in flavouring of food and drinks for different industries. The value of the essential oil is directly related to the quality of the oil. Therefore, it is important that the geranium growers take good care of agricultural practices in the production of essential oils as it is a crucial step where oil quality and yield is either obtained or lost. Thus, growing conditions and harvesting time must be cautiously established and controlled including herbage drying to ensure optimum yields and high quality of rose-scented geranium oil. The geranium oil production industry in South Africa is still expanding and oil yield & quality variation is important. This study was undertaken to determine the effects of herbage drying and method, leaf age and paclobutrazol concentrations on oil yield and quality of rose-scented geranium. The responses of oil yield and quality to drying effect was conducted on plant materials which were harvested from the University of Fort Hare Research Farm and glasshouse in December 2014 and October 2015. To determine the effect of drying method on essential oil yield and composition of rose-scented geranium the harvested leaves were dried in direct sunlight (20-35℃) and in a shade conditions (25℃/room temperature). Essential oil was obtained by hydro-distillation using a Clevenger apparatus. The oil samples were analysed by gas chromatography (GC) at the Dohne Agricultural institute. The major components of the oil conducted under the shade method were Linalool (5.58 percent), Menthone (0.68 percent), Citronellol (36.14 percent), Geraniol (7.29 percent), CitronellylFormate (15.39 percent) and GeranylFormate (3.30 percent), whereas those that were sun dried comprised of Linalool (3.56percent), Menthone (0.76 percent), Citronellol (32.25 percent), Geraniol (6.49 percent), CitronellylFormate (14.84 percent) and GeranylFormate (3.15 percent). The analysis of variance showed that freshly dried herbage followed by shade drying is suitable for highest oil yield. In addition, changes in essential oil composition and oil yield with leaf age in rose-scented geranium (Pelargonium capitatum x P. radens cv. Rose) were investigated in a glasshouse of the University of Fort Hare, during January to April and April to August 2012. The plants were allowed to grow to about 12-leaf stage. From top to bottom, the leaves were put into five groups (each group comprising two successive leaves, Pairs 1, 2, 3, 4 and 5). Leaf growth (leaf fresh and dry mass), and essential oil yield and composition data were collected and compared. The results indicated that, leaf fresh and dry mass data were significantly lower in the top-most (youngest leaves) as compared with the rest of the leaf pairs harvested. Essential oil in the youngest leaves was colourless, but as the leaves advanced with age, the oil tended to have a blue-green colour. Oil content (on dry mass basis) from the top to bottom, for Leaf Pairs 1, 2, 3, 4, and 5 were about 7.0, 4.9, 3.2, 2.4, 1.9 percent, respectively. Oil yield showed a significant increase in the second youngest pair of leaves and progressively declined, resulting in a significant lower yield in the oldest leaves. Leaf Pairs 1, 2, 3, 4 and 5, contributed about 19.3, 22.0, 17.71, 12.03 and 8.5 percent of the total yield per branch, respectively. Citronellol:Geraniol ratio was significantly lower in the young leaves than in the old leaves. Linalool and Geranylformate concentrations were the highest in the youngest leaves, and the opposite was observed in isomenthone. Other essential oil components did respond to leaf age. In support of research by Góra et al. (2002), Motsa et al. (2006) and Southwell and Stiff (1989), the current results indicate that early leaf age affects essential oil yield and composition. Thus, shorter regrowth cycles would increase essential oil yield and quality of rose-scented geranium. The paclobutrazol experiment was conducted in a glasshouse at the University of Fort Hare, Alice. A randomized complete block design with four replications was applied. One month after cutting back of the plants, PBZ was applied at the rates of 0, 100, 200 and 300 mg/l on the regrowth and harvested at four months of age. Data, such as chlorophyll content, plant circumference, plant height, fresh and dry mass and oil composition, were determined. The results highlighted that with an increase in PBZ concentration, total herbage mass and plant height tended to decline (Esmaielpour et al., 2011). Thus, in most cases herbage fresh and dry weight of treated plants had lower weight than the control. Paclobutrazol significantly reduced canopy circumference. There was no significant difference (P< 0.05) in oil yield and composition. Furthermore, observations showed that plants receiving PBZ had a deep green colour although the chlorophyll data did not show a significant difference. These results clearly show that PBZ helps geranium plants with compact canopy, which would enable farmers to increase income by increasing planting density, reducing distillation cost of the herbage volume and mass without reducing oil yield per plant. The findings, add another dimension to practical use of this hormone for commercial cultivation.
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Ruthenium (II) complexes of mixed bipyridyl and dithiolate/thiourea ligands :|bsynthesis, characterization, photophysical and electrochemical studies
- Authors: Nkombi, Pelokazi
- Date: 2018
- Subjects: Ruthenium Ruthenium compounds Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10134 , vital:35358
- Description: Energy is one of the most important factor to influence human lives. The increased in energy demand as well as the detrimental effects posed by emission of greenhouse gases due to continue use of fossil fuels for electricity generation has led to a renewed focus on energy production using renewable energy sources which are relatively cheap, clean and environmentally sustainable. Among the various renewable energy sources used so far, the Dye Synthesized Solar Cells (DSSCs), a form of photovoltaic device is reported for their better efficiencies despite their low cost of production and ability to work relatively under low light conditions. A recent report on the solar-to-electricity conversion efficiency of a typical DSSC sensitizer made from zinc based porphyrin dye coupled with sintered titanium(IV) oxide as semiconductor was 13 percent. In this study, 2,2-bipyridyl-4,4-dicarboxylic acid (bpydc) was used as mixed ligand and four dithiolate ligands; L1 = dipotassium ethoxycarbonyl-1-cyanoethylene-2,2-dithiolate, L2 = dipotassium bis(ethoxycarbonyl)ethane-2,2-dithiolate, L3 = dipotassium cyanodithio imidocarbonate and L4 = dipotassium 2,2-dicyanoethylene-2,2-dithiolate were synthesized while four alkyl thiourea ligands, L5 = 1,3-dimethyl thiourea, L6 = 1,3-diethyl thiourea, L7 = 1,3-diisopropyl thiourea and L8 = 1-methyl thiourea were purchased and used as supplied without further purification. These ligands were used to prepare eight ruthenium(II) complexes of mixed bipyridyl/dithiolate/thiourea. The compounds were characterised by elemental analysis and spectroscopic techniques, namely: Fourier transform infrared (FTIR), Nuclear Magnetic Resonance (NMR), ultraviolet-visible and photoluminescence (PL). Cyclic voltammetry (CV) and square wave voltammetry (SWV) were used for the electrochemical studies. Photoluminescence and UV-Vis spectroscopies were used for geometric and photophysical studies of the complexes respectively. FTIR spectra confirmed presence of functional groups in ligands and coordination of these ligands to ruthenium(II) ions to form complexes. The UV-Vis confirmed that the Ru(II) dithiolene complexes exhibited square planar geometries while the Ru(II) thiourea complexes gave octahedral geometries, this was deduced from the transitions assigned to the complexes. All the ruthenium(II) complexes synthesized showed photoluminescence properties that are suitable for light harvesting and application for dye-sensitized solar cells. Cyclic and square wave voltammetry show Ru(II) thiourea complexes have better redox properties when compared to Ru(II) dithiolate complexes which is ascribed to ligand strength field possibly due to contribution from the two bonded NCS groups.
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Smallholder farmers' selection criteria of maize varieties in Eastern Cape Province (Implications for adoption of GM maize) : the case of Port St. Johns, Flagstaff and Mqanduli
- Authors: Ngcinela, Siphokazi
- Date: 2018
- Subjects: Genetically modified foods
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10178 , vital:35372
- Description: Different maize varieties are produced by smallholder farmers in Eastern Cape Province in different agro ecological zones. Government cropping programmes have been promoting the production of GM maize varieties by smallholder farmers to enhance food security. However, there is no evidence to show how smallholder farmers are selecting the maize varieties they want to produce. On the other hand, smallholder farmers are slowly adopting GM maize due to number of factors affecting them. The study adopted Cross sectional design to collect the data from smallholder farmers from the three study sites. The sample size was 704 respondents. A semi structured questionnaire was used to collect primary data from smallholder farmers in Mqanduli (Lowest rainfall), Flagstaff (moderate rainfall) Port St. Johns LM (highest rainfall), under OR Tambo DM. Multistage sampling was utilised. SPSS version 24 was used to analyse descriptive statistics and Multinomial logistic regression model. STATA version 13 was used to analyse Crag’s double hurdle model. The results showed that, farmers were producing GM maize (Ht and Bt), unimproved OPV (landrace) and improved OPV (Sahara). The majority of farmers were producing OPVs. The findings further showed that, the selection of GM maize varieties is positively related to maize threat stalk borer damage. The results indicated that, most of the respondents were not aware of the GM permit conditions thus, they failed to comply with the expected conditions. The following variables influenced the adoption and intensity of adoption of GM maize: gender, highest educational level, household size, employment status, access to land, access to market, access to credit, membership to farmers group, main source of income, farm size, and access to extension services. It was concluded that from the three study areas different maize varieties were produced. Adoption of GM maize was influenced by the number of factors. GM maize permit condition were not met by smallholder farmers. It was recommended that, research should be done on OPVs which are the most preferred varieties by smallholder farmers. Extension officers and those who are adopting GM maize should be educated and trained about GM maize permit conditions.
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Synthesis, characterization and in vitro antiplasmodial evaluation of 4-& 8-aminoquinoline based-hybrid compounds
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
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Synthesis, characterization and photophysical studies of RU(II)bipyridyl-dithiocarbamate complexes as sensitizers for dye sensitized solar cells
- Authors: Fudo, Zintle
- Date: 2018
- Subjects: Dye-sensitized solar cells Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6168 , vital:29498
- Description: The depletion of fossil fuels and the increasing energy demand for energy has led to the search for better and improved technologies with special focus renewable energy, especially solar cells. The first generation solar cells based on silicon are expensive, hence dye sensitized solar cells come in as a better alternative as these solar cells are environmental friendly, they have moderately good conversion efficiency and they are relatively cheap to produce. Dithiocarbamate ligands have been widely used in many research fields, as these are versatile ligands. Coordination of dithiocarbamates with metals such as ruthenium has produced high conversion efficiency and have the ability to extend the MLCT absorptions, and this can further extend their wavelength. In this study five dithiocarbamate sodium salt ligands were prepared and were coded as FL1= Aniline, FL2= p- toluidine, FL3= p- anisidine, FL4=dibenzyl, FL5=diphenyl. These ligands were used to synthesize Ru(II) metal complexes which were formulated as [Ru(FLx)(dcbpy)(NCS)] and [Ru(FLx)2(dcbpy)] where FLx is the dithiocarbamate ligand and dcbpy is 2,2-bipyridine-4,4’-dicarboxylic acid and the complexes were coded as FCx. The synthesized compounds were characterized using techniques such as the melting point, molar conductivity, FT-IR and NMR spectroscopy. For spectroelectrochemical studies of the metal complexes, techniques such as UV-Vis and photoluminescence spectroscopy were carried out. Furthermore, redox properties of the complexes were analyzed using cyclic and square wave voltammetry. The FT-IR displayed all the expected peaks of interest both in the dithiocarbamate ligands and in the metal complexes. The electronic spectra confirmed the successful coordination of ligand to the metal centre, the electronic spectra of the complexes also confirmed the six coordinate octahedral geometry of the complexes. The complexes exhibited some photoluminescence properties that are suitable for dye sensitization. The cyclic voltammogram of the complexes displayed more reduction potentials that could be attributed to the π-conjugation in the ligands incorporated during synthesis. The square wave voltammogram of the complexes is in agreement with the results obtained in cyclic voltammetry.
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The contribution of small-scale fisheries to rural livelihoods and food security : evidence from Hamburg, Eastern Cape Province, South Africa
- Authors: Budaza, Nwabisa
- Date: 2018
- Subjects: Small-scale fisheries -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Fishery management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10338 , vital:35396
- Description: Small-scale fisheries are known to provide food and income to millions of people around the world, but their role and existence is often ignored in development planning. The growing human demand for animal protein has become one of the foremost world challenges for which aquatic organisms have a significant role to play. In South Africa, small-scale fisheries have been recognized since the end of Apartheid, but the extent of the contribution of the sector to rural livelihoods and food security is not well understood. Using data drawn from a sample of 80 fishers in the coastal community of Hamburg, Eastern Cape, this dissertation presents an assessment of the contribution of small-scale fisheries to rural livelihoods, income and food security. The primary data were collected from the fishers using a structured questionnaire and non-probability sampling. The data were analysed with the assistance of descriptive techniques and a few simply statistical tests. The results of the study indicate that fishers in Hamburg catch a wide range of fish, which include wild kob, octopus, spotted grunter, white/black mussel cracker and white steenbras. Fishers in the study area are not solely dependent on small-scale fisheries for their livelihoods, income and food security, but generally supplement their welfare payments with fishing in order to sustain their livelihoods. About 78percent of the surveyed fishers depend on government grants, including old age grants, child support grants and social care grant. In terms of employment, 15percent of the surveyed fishers are casually employed, while 6percent are formally employed on a contract basis. Although they are not only dependent on fishing, nevertheless fishing is an important source of livelihood, income and food security. About 37percent of the fishers harvest marine resources for home consumption, while 7percent harvest solely for income, and 56percent harvest for both home consumption and income. Income generated from fisheries is approximately R935 per month and is used to buy food, electricity, fishing equipment and other household needs. The findings from this research underline the need for interventions such as coordinated institutions, improved infrastructure, improved monitoring and enforcement systems, as well as improved access to permit/fishing rights for sustainable use of marine resources.
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