Effect of increasing fossil shell flour levels on digestive and metabolic utilization, health, body weight change and wool production, and quality in Dohne-Merino wethers
- Authors: Ikusika, Olusegun Oyebade
- Date: 2020
- Subjects: Merino sheep Sheep -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18465 , vital:42542
- Description: The study's broad objective was to assess growth performance, blood and parasitic profiles, wool parameters, methane emission, and nutritional status of Dohne-Merino wethers fed diets supplemented with varying levels of fossil shell flour. Twenty-four Dohne-Merino wethers, averagely weighing 20.0±1.50 kg, were divided into four groups and used in this study. The effects of varying inclusion levels of fossil shell flour (FSF) (0, 2, 4, and 6 %) on feed intake, water intake, nutrient digestibility, N-retention, hematobiochemical and parasitic profiles, body condition scores, feed preference, wool parameters and methane output were determined. The influence of FSF's varying inclusion levels on fermentation parameters, in vitro true digestibility, and relative feed values were also determined. Wethers fed with 4% FSF inclusion level diet showed the highest (P<0.05) values for dry matter intake, average daily weight gain, N retention, (Nitrogen retention) and apparent digestibility of crude protein (CP), Ether Extract (EE) and Ash 6 % (P < 0.05). The urinary N and fecal N were lowest in wethers fed 4% FSF inclusion level and highest in those fed on diets without FSF (P < 0.05). Water intake was highest in wethers fed 0% FSF diet, followed by those fed on 4% and lowest in 6% FSF (P< 0.05). There was a significant increase in white blood cell counts in wethers fed on a diet with 4% and 6% FSF inclusion levels from day 10 to 100 compared to wethers fed on a diet with 0% and 2% FSF (P <0.05). Red blood cell counts also increased significantly in wethers fed on a diet containing 4% FSF, but a slight increase in wethers with 6 % FSF diet, throughout the experimental period (P < 0.05). Blood urea was highest in wethers fed 0% FSF inclusion level and lowest in 6% at day 30 to day 100. Wethers on 4% FSF diet showed an increase in blood urea from day 30 to day 100 (P < 0.05) while wethers on 0% and 2% remained unchanged (P<0.05) during this period and not different (P > 0.05) from wethers on 4% FSF as well. The total protein concentration, albumin, total bilirubin, Na, K, glucose, cholesterol, and liver enzymes were normal for wethers. However, serum creatinine level was lower in wethers fed on 4% FSF than those on 0% FSF (P < 0.01). Haemonchus and Coccidian fecal egg counts were low in wethers fed diets with 2%, 4%, and 6 % FSF (P < 0.01) compared 11 with wethers fed with 0% FSF inclusion level during the same period. The body condition score of wethers fed on diets with 2%, 4%, and 6% FSF inclusion levels were higher than those on 0% (P < 0.05). Wool yield, staple length, the coefficient variation of the fibre diameter, and fibre of wethers fed on diets with FSF were higher than those without FSF (P < 0.05). The fibre diameter of the wethers fed on FSF supplemented diets was the same as those on 0 % FSF (P > 0.05). The wethers spent more time on FSF supplemented diets and consumed more feed compared to that without FSF supplemented (P < 0.05). The levels of FSF inclusion in the diet affected the enteric methane output (ppm-m), where 4 % FSF had the highest enteric methane output while wethers on 2 % FSF had the lowest methane output (P < 0.05). Resting wethers produced more methane (g/day) than those feeding or standing (P < 0.05). Increasing levels of FSF did not affect ruminal temperature and pH. Ammonia-N increased with increasing FSF except in wethers fed on a diet with 4% FSF (P < 0.01). The total molar concentrations of the wethers' volatile fatty acids decreased with increasing FSF levels (P > 0.05). The acetic propionic ratio of the wethers also decreased except at a 4% inclusion level. The in vitro true digestibility dry matter (IVTDDM), in vitro true digestibility neutral detergent fibre (IVTDNDF), and in vitro true digestibility acid detergent fibre (IVTDADF) of the wethers decreased up to 4% FSF inclusion but tended to increase at 6% inclusion. This study's result as one of the pioneer studies in Dohne-Marino wethers showed that FSF treatment has the potential to improve the nutritional status of the animal and the animal performance and wool quality. Health-wise, FSF decrease nematode population and boost animal immunity as seen in RBC and WBC counts. It also can play a major role in protecting the environment, as seen in its reduction in feacal and urinary nitrogen, which is heavily involved in environmental pollution. Result also confirmed that the best period to target for methane mitigation in ruminants is the resting period. In conclusion, the inclusion of FSF in the diet of Dohne-Merino wethers has the potential to improve the overall performance, with a 4% FSF inclusion level having optimal productivity. However, future research is required to investigate FSF's effect on meat quality, rumen microbial community, in-vivo digestibility, and milk production.
- Full Text:
- Date Issued: 2020
Joint Modelling Inference for Longitudinal and Time To Event Data with Application to Biomarkers in Medical and Clinical Studies
- Authors: Azeez, Adeboye Nurudeen
- Date: 2020
- Subjects: Biochemical markers Bayesian statistical decision theory
- Language: English
- Type: Thesis , Doctoral , PhD (Biostatistics)
- Identifier: http://hdl.handle.net/10353/18476 , vital:42543
- Description: In the past couple of decades, longitudinal and survival data analysis have emerged as important and popular concepts of biostatistics and statistics for disease modelling. In recent years, these two statistics concepts have been combined to develop a joint model for longitudinal and survival data analysis. The Joint model is a simultaneous modelling application of longitudinal and survival data while taking into account a possible association between them. In this thesis, three sub-topics (Conditional score approach, estimating equation approach, and modified Cholesky decomposition approach) are utilised to model the association if the independence assumption is violated. Using the conditional score approach, the study investigated the association between longitudinal covariates and the time-to-event process to examine the within-subject measurement error that could influence estimation when the assumption of normality and mutual independence is violated. Given the assumption violation, I proposed an estimating equation approach based on the conditional score to relax parametric distributional assumptions for repeated measures of random effects. I jointly modelled the time-dependent biomarkers and event times using the Cox model with intermittent time-dependent covariates measure, in which the longitudinal model was used to characterize the biomarker underlying (unobservable) trajectory and incorporated as a latent time-dependent covariate in the survival model to predict failure times. Estimates of the parameters were obtained by a restricted maximum likelihood estimate (REML). A modified Cholesky decomposition method was used to capture the within-subject covariance for a positive definite and symmetric matrix, with the assumption that the observed data from different subjects are independent. I illustrated the proposed method by a real data set from a lung study and simulation. An extension to the joint model of longitudinal-survival data was also proposed, in which the longitudinal data has a cumulative and weighted effect on the hazard event function. Using a Bayesian parametric method, I proposed a skewed weighted probability density function to estimate the parameters. The weighted cumulative effect used enabled different longitudinal profiles to be incorporated over time in calculating the hazard ratio between the subjects. The proposed functions provide greater flexibility for modelling the association structure of different longitudinal and survival sub-model. The focus was on the association between the biomarker (serum creatinine, sCr) and the development of end-stage renal disease (ESRD). Since the effect of sCr biomarker is anticipated to be a cumulative effect, with the development of sCr biomarker over time leading to progressively higher damage of the kidney. The approach was applied a simulation for validation of the proposed method
- Full Text:
- Date Issued: 2020
Resource Allocation Framework in Fog Computing for the Internet of Things Environments
- Authors: Vambe, William Tichaona
- Date: 2020
- Subjects: Internet of things Cloud computing
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: http://hdl.handle.net/10353/18498 , vital:42575
- Description: Fog computing plays a pivotal role in the Internet of Things (IoT) ecosystem because of its ability to support delay-sensitive tasks, bringing resources from cloud servers closer to the “ground” and support IoT devices that are resource-constrained. Although fog computing offers some benefits such as quick response to requests, geo-distributed data processing and data processing in the proximity of the IoT devices, the exponential increase of IoT devices and large volumes of data being generated has led to a new set of challenges. One such problem is the allocation of resources to IoT tasks to match their computational needs and quality of service (QoS) requirements, whilst meeting both task deadlines and user expectations. Most proposed solutions in existing works suggest task offloading mechanisms where IoT devices would offload their tasks randomly to the fog layer or cloud layer. This helps in minimizing the communication delay; however, most tasks would end up missing their deadlines as many delays are experienced during offloading. This study proposes and introduces a Resource Allocation Scheduler (RAS) at the IoT-Fog gateway, whose goal is to decide where and when a task is to be offloaded, either to the fog layer, or the cloud layer based on their priority needs, computational needs and QoS requirements. The aim directly places work within the communication networks domain, in the transport layer of the Open Systems Interconnection (OSI) model. As such, this study follows the four phases of the top-down approach because of its reusability characteristics. To validate and test the efficiency and effectiveness of the RAS, the fog framework was implemented and evaluated in a simulated smart home setup. The essential metrics that were used to check if round-trip time was minimized are the queuing time, offloading time and throughput for QoS. The results showed that the RAS helps to reduce the round-trip time, increases throughput and leads to improved QoS. Furthermore, the approach addressed the starvation problem, a phenomenon that tends to affect low priority tasks. Most importantly, the results provides evidence that if resource allocation and assignment are appropriately done, round-trip time can be reduced and QoS can be improved in fog computing. The significant contribution of this research is the novel framework which minimizes round-trip time, addresses the starvation problem and improves QoS. Moreover, a literature reviewed paper which was regarded by reviewers as the first, as far as QoS in fog computing is concerned was produced.
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- Date Issued: 2020
Synthesis and characterization of binary and ternary palladium alloys for use as alternative counter electrode catalysts in dye sensitized solar cells
- Authors: Zingwe, Nyengerai Hillary
- Date: 2020
- Subjects: Electrocatalysis Chemistry
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: http://hdl.handle.net/10353/18513 , vital:42580
- Description: The dye sensitized solar cell counter electrode facilitates the regeneration of the dye molecules thereby ensuring the provision of higher sunlight to electricity conversion efficiency. The standard platinum electrode suffers from low efficiency due to corrosion by the redox mediator as well as being extremely expensive due to high demand. As an alternative this research study illustrates the efforts undertaken to replace the standard platinum counter electrode with palladium alloy counter electrodes. Application of palladium alloys ensures sustenance of high catalytic activity by palladium which is as effective as platinum. Although palladium is equally as expensive as platinum, its application in the form of alloys minimizes the amount required to produce an effective counter electrode to 0.001-0.004 moles thereby ensuring the provision of high efficiency at a lower cost. Furthermore, charge transfer from the other alloyed elements to the palladium atom increases active sites leading to higher catalytic activity than platinum. Additionally, changes in crystal structure due to alloying enhances resistance to corrosion thus enabling the longevity of the alloy counter electrode in the electrolyte ___________________________________________________________________________ Electrochemical analysis was conducted to determine the catalytic functionality of the developed alloys in cobalt, ferrocene and iodine redox mediators. The binary (PdNi-reduced graphene oxide (rGO) and PdCo-rGO) and ternary (PdNiCo-rGO) palladium alloys were fabricated via a hydrothermal method. In order to determine the composition which could provide the maximum activity, optimization was conducted through variation of the molar ratios of the precursor solutions. The properties of the synthesized palladium alloys were determined using various techniques including x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The developed alloys were observed to comprise of palladium, nickel, cobalt, and carbon atoms. The particles were spherical in nature for all the unsupported alloys with the carbon supported alloys exhibiting spherical particle wholly surrounded by graphene sheets. Cyclic voltammetry and electrochemical impedance spectroscopy analysis showed that the carbon supported alloys PdNi-rGO, PdCo-rGO and PdNiCo-rGO produced the highest catalytic activities due to the synergy between their respective alloys and the incorporated reduced graphene oxide. The high catalytic effectiveness of these alloys yielded power conversion efficiency in the order PdNiCo-rGO (9.01) > PdNi-rGO (8.4.%) > PdCo-rGO (6.56%) > Pt (5.7%) which were better than the platinum efficiency in the cobalt redox mediator. The higher efficiency in the cobalt redox mediator relative to the iodine electrolyte illustrates that they are viable alternatives to the, corrosive and volatile iodine. Obtained results show that, the high recombination rates between the photogenerated electrons and the oxidized dye molecule which have been reported to reduce power conversion efficiency in one electron redox mediators did not affect the performance of the cell. However, these higher recombination rates affected the ferrocene electrolyte leading to extremely poor efficiency metrics. The obtained results indicated that reduced graphene oxide supported PdNi-rGO, PdNiCo-rGO as well as the unsupported PdNi3 alloys could successfully be implemented as substitutes to the platinum counter electrode in dye sensitized solar cells. The application of the palladium alloys is vital for improving stability and power conversion efficiency, as well as reducing cost.
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- Date Issued: 2020
Towards a reconstruction of Marion Island’s glacial history
- Authors: Rudolph, Elizabeth
- Date: 2020
- Subjects: Glacial landforms Geomorphological mapping
- Language: English
- Type: Thesis , Doctoral , PhD (Geography)
- Identifier: http://hdl.handle.net/10353/18531 , vital:42581
- Description: Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topography, but also in oceanic situation when compared to other continental landmasses (e.g. Antarctica or Patagonia). On sub-Antarctic Marion Island, southern Indian Ocean, the exact timing and extent of the local Last Glacial Maximum is not yet known as glacial reconstructions have mostly been based on palynological proxies and relative-age dating techniques. This study presents 29 cosmogenic 36Cl exposure ages of deglaciated bedrock surfaces and moraine deposits from Marion Island. In addition, a comprehensive glacial-geomorphological map, which in conjunction with exposure ages provide improved temporal and spatial constraints for the island’s glacial history. Results show that the ice reached a local Last Glacial Maximum before 56 ka ago and retreated, with minor stillstands, until ~17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after ~19 ka, and any subsequent advances during the Late Glacial or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maximum earlier than the global LGM. A combination of climatic drivers such as declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere Westerly Winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage 4 (MIS 4; ~65 ka ago) instead of the global LGM in MIS 2 (~18 ka). These findings redefine the glacial history of Marion Island, and have implications for future investigations on post-glacial landscape development and ecological succession.
- Full Text:
- Date Issued: 2020
Analyses of Retail and Transport Geography of Liquefied Petroleum Products in Ibadan metropolis, Nigeria
- Authors: Ajayi, Adeyinka Peter
- Date: 2019
- Subjects: Petroleum products
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/19065 , vital:40090
- Description: This study analyzed the effects that spatial arrangement of petroleum products retail outlets and the supply chain management techniques employed for products distribution (for both intra city and intercity shipments) have on the retailing dynamism of petroleum products within built environment and peripherals of Ibadan metropolis over the years. Specifically, the study investigated the differentials in the spatial configurations of petroleum products retail outlets between the core and periurban zones of the metropolis. An attempt was made to determine the explanatory variables that influence the spatial distributional decisions of petroleum products retail outlets in the metropolis. The study equally examined how the supply chain management (SCM) techniques by the different categories of the retail outlet owners influence the efficient and cost effective distribution of petroleum products. Lastly an attempt was made to analyze the relationship between the socio-economic attributes of the haulers and the achievement of compliance to the HSE stipulations guiding the conveyance of petroleum products. The theoretical underpinnings for the research were a derivative of the amalgamation of normative and psychological theories from geography, psychology, SCM and retailing science. Specifically, Expectation Disconfirmation Theory (EDT), Distributive Justice, Central Place Theory (CPT) Theories of Urban Impact (TUI) and Theory of Constraint (ToC) were the theories utilized in the study. For the achievement of the first objective which was to investigate the possible differential in the compliance rate between spatial pattern of fuel retail outlets in the core and peripheral zones of Ibadan metropolis, the first hypothesis of the study (which examined if there was no significant difference in the rate of compliance to the planning authority stipulations guiding the location pattern of petroleum product retail outlets between those located in the built up and xxiv peripheral zones of the city), was tested through the use of buffering and proximity analyses in the ArcMap environment of ArcGIS 10.1, while inferential statistical tool of an independent-samples t-test was conducted to compare the rate of compliance to the stipulations guiding the locations of these outlets in both the core and the peripheral zones. The result from the GIS analysis indicated that 33 (15.56%) out of the 220 outlets in the core zone of the metropolis complied with the planning stipulations guiding the location of fuel retail outlets. For the peripheral zone, out of the 220 fuel retail outlets 24 (10.90%) complied with the stipulations. The result from the t- test which was employed to test the hypothesis indicated that no significant difference existed in the rate of compliance t (263) =-2.66, p = 0.08 between fuel retail outlets in the core zone (M=3.9, SD=1.4) and peripheral zone (M=4.5, SD=1.79). The alternate hypothesis which stated that ―no significant difference existed in the compliance rate between fuel retail outlets located in the two zones‖ is accepted. For the achievement of the second objective of the study which was to analyze the factors which determine the location of fuel retail outlets both in the core and peripheral zones of Ibadan metropolis. All the managers/owners of the 432 fuel retail outlets in the metropolis were sampled out of which 256 questionnaires were retrieved for the purpose of this analysis. The breakdown of the socio-economic characteristics of the sampled respondents showed that the gender distribution showed that 194 (75.78%) of the respondents were males, while 64 (24.22 %) were females. The average age of the sampled population was 33.70 years. The mixed method was employed for the achievement of the second objective of this study. Logistic Regression Model (LRM) was employed to test the hypothesis and the result revealed that the inclusion of the independent variables in the model increased the overall level of it accuracy. The overall significance revealed that the Model Chi- xxv Square, derived from the likelihood fitted is also accurate (X2 = 43.47, df=5, p>.05). The model chi-square value of 43.47 (approximately 44% ) was significant. Thus, the indication is that the model has a good fit in predicting the possibility of a fuel retail outlet being located in the core or peripheral zone of the metropolis as determined by the explanatory variables (the independent variables accounted for about 44% of possible factors which determined whether a fuel retail outlets is located either within the core or peripheral zones of the metropolis. The remaining 56% are factors not considered in the study). The result gotten from the in depth interview sessions corroborated the findings from the tested hypothesis. The third objective was to examine the effects which the supply chain technique employed (either vertically integrated model or third-party arrangement) has on the achievement of efficient and effective distribution of the products. In order to achieve this objective, all the 389 registered members of Petroleum Tanker Drivers (PTD) association who are members of the PTD in the metropolis were sampled, 265 (around 70%) of the distributed questionnaires were retrieved and used for the analysis. In depth interview sessions were also conducted with three different managers of the three major conglomerates in the downstream sector of the Nigerian petroleum sector. The result of one-way between subjects (ANOVA) which was conducted to compare differences in the management and performances of haulage services outsourced to the 3PLS and those run under VIM showed that there was a significant effect of ownership type on management performance (F (2,262) = 60.26, p<.05). The null hypothesis was therefore rejected while the alternate hypothesis was accepted. The findings from the interview sessions posted similar results. The fourth and final objective was to analyze the effect that the socio-economic attributes of the participants (haulers and managers of retail outlets) involved in the distribution of xxvi petroleum products has on the safe, efficient and cost-effective distribution of product and this was done through the use of descriptive statistics, inferential statistics and incisive analysis of the interview sessions. A total number of 265 (70%) out of the 389 registered members of Petroleum Tanker Driver Association (PTDA) participated in the study. Multiple regression analysis (MRA) was used to test this hypothesis. The result from the statistical analysis show that the use of stimulant, work condition, marital status and educational attainment/literacy level have joint influence on compliance (R2 = 0.31, F (4,260) = 29.72, p<.05). On the basis of the foregoing, the hypothesis is thus accepted. The result from the interview sessions confirmed the existence of strong relationship between the explanatory variables and the hypothetical dependant variable. The study recommended a review of the planning processes guiding the establishment of fuel retail outlets. The study also advocated that retailers should endeavour to have stronger control over the supply chain of their products this could done by investing more in VIM rather than outsourcing such functions to 3PLs. This will help in better business performances. Government agencies in charge of monitoring drug abuse among haulers are advised to be more proactive by the duo of prevention and punishment strategies. This should include advocacy campaign against drug abuse. Different ranges of punishments should also be meted out for individual haulers found culpable.
- Full Text:
- Date Issued: 2019
Application of some missing data techniques in estimating missing data in high blood pressure covariates
- Authors: Odeyemi, A. S
- Date: 2019
- Subjects: Missing observations (Statistics) Hypertension
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15189 , vital:40195
- Description: Cases recorded with high blood pressure are a major concern in both public and private hospitals. Adequate provision of health information of patients relating to high blood pressure in Eastern Cape Hospitals hinges so much on the outcome of statistical analysis results. The usual statistical methodologies become inadequate in handling statistical analysis of data collected due to incomplete patients’ information stored in the hospital database. From time to time, new methods are developed to address the problem of missing data. High blood pressure is linked to a lot of diseases such hypertension, cardiovascular disease, kidney disease and stroke. In this study, we developed a new method for addressing the problem of missing data in assessing model used for estimating missing values in terms of minimum errors(using RMSE, MAE, and SE) and goodness-of-fits(using 2 R and adjusted 2 R ) of this model and P-value. . The study compared six different methods: Original data (OD), Listwise deletion (LD), Mean imputations (MEI), Mean above (MA), and Mean above below(MAB) and two steps nearest neighbour (2-NN).The comparison was performed using original data set, and missing values at 5%, 10%, 20%, 30% were simulated on Framingham risk scores under MCAR and MAR simulation on BMI values given some assumptions. Five performance indicators were used to describe the model minimum errors and goodness of fit for all the methods. The results showed that the 2-NN is the best replacement method at lower levels (5% and10%) of missing values while MA and MEI performed best at higher levels(15% and 20%) of missing values. All comparison was based on estimates closest to those of the original data where no value was missing. MAR results showed that 2-NN performed better than LD,MA,MAB, and MEI at 5%,10%, and 20% levels of missing data in terms of absolute difference in p-value to original data.
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- Date Issued: 2019
Characterization of the heat source of thermal aquifers within the Soutpansberg Basin in the Limpopo Province, South Africa: Evidence from geophysical and geological investigations
- Authors: Nyabeze, Peter Kushara
- Date: 2019
- Subjects: Basins (Geology) -- Analysis Geology, Structural -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: http://hdl.handle.net/10353/15167 , vital:40192
- Description: The research was conducted to contribute towards the knowledge base on the potential for geothermal energy in the Soutpansberg Basin, located in the Limpopo Province of South Africa. The focus area was Siloam, an area that hosts a hottest spring with the highest recorded temperature of 67.5°C. The research involved visits to the Soutpansberg Basin, water sampling, carrying out ground geophysical surveys, and high-level processing of airborne magnetic data to determine depths and temperatures of magnetic sources. The water samples from the hot springs were found to be enriched in sodium, bicarbonate and chlorine with very low concentrations of other element species. The chemical composition of the spring water indicated a source chemistry comprising of the Na-ClHCO3 water assemblage that is a typical signature for deep circulating groundwater of meteoric origin. The circulation depth was inferred to be 2.0 km. The increased resolution of the ground magnetic, electrical resistivity tomography, and electromagnetic conductivity methods data made it possible to delineate subsurface structures at the spring such as dykes, sills, faults and fractures from generated depth models. Modelling of ground magnetic data showed that the Siloam hot spring occurred between two interpreted north dipping dykes approximately 150 m apart. The minimum depth extent of the dykes was interpreted to be 650 m. The magnetic susceptibility values determined from rock measurements and modelling of magnetic data indicated the presence of volcanic and metamorphic rocks. Electromagnetic profiling data showed that there were three main high conductivity zones in the study area with values above 100 mS/m; A central zone associated with the spring; A zone to the south of the spring and a north zone associated with the Siloam Fault. Ground geophysics survey results confirmed the existence of the Siloam Fault. Two artesian boreholes with water warmer than 40 °C were identified to the south of the Siloam hot spring. Both electromagnetic conductivity and electrical resistivity tomography surveys delineated lateral and vertical variation in the bedrock to depths of 40 m to 60 m. Water bearing structures that could be faults, or fractures were identified. Layering due to weathering and water content was found to be in the depth range of 20 m to 40 m. The depths of the potential heat sources were computed from the radially averaged power spectrum of airborne magnetic data for square blocks with side dimensions L of 51 km, 103 km, and 129 km. Spectral analysis based approaches namely Centroid method, Spectral peak method, and the Fractal based approach were used for computing depth and temperatures to heat sources. Airborne magnetic data sets with larger window sizes were preferred for depth computations, as they preserved spectral signatures of deeper sources and reduced the contribution of shallower sources. The size of the data windows did not have a marked effect of depth and temperature values. Shallower magnetic sources depths of approximately 2.0 km were delineated using the Euler deconvolution method. An anticlinal feature at depths of 2.0 to 4.5 km was 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper delineated in the central part of the basin. Spectral analysis results indicated that the depth to the top of magnetic sources was at 3.5 km to 6.2 km; the centroid of the basement at 7.92 km to 13.41 km, and the basal below 11.09 km and 14.08 km. The lower end depth spectrum was determined from application of the Centroid method with the deeper being results from the Fractal based approach. The Spectral peak method was useful for determining the depth to the top of magnetic sources. The temperature of the top of magnetic sources and basement centroid were computed to be in the range 234.00 °C to 281.34 °C. Magnetic source depths and basal temperatures that were in the Curie point range within which rocks lose magnetism due to heat were determined, using a computation approach that utilised fractal parameters, to be 21.39 km and 577.42 °C, respectively. Increasing the value of the fractal parameter β from 0 to 4, had an effect of retaining deeper depths and higher temperatures. The fractal parameter β range of 3 to 4 that gave the Curie point parameters indicated basal rock types with an igneous predisposition. The research highlighted evidence for the existence of the Soutpansberg Basin Geothermal Field (SBGF). The area around Siloam is a potential target for drilling exploration geothermal energy boreholes based on the occurrence of hot springs, shallow heat source depths, anticlinal structure, high formation temperatures, deep circulating water and the achieved Curie point temperature.
- Full Text:
- Date Issued: 2019
Diversity, host plant range and ecology of Lepidoptera stem borers in South Africa
- Authors: Stemele, Mxolisi Arnold
- Date: 2019
- Subjects: Lepidoptera Host plants Stem borers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15409 , vital:40405
- Description: The biology and ecology of Lepidopteran pests stem borers has been extensively studied because of the economic importance of pest species such as Busseola fusca (Fuller) (Noctuidae), Sesamia calamistis (Hampson) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae), and Eldana saccharina (Walker) (Pyralidae). Knowledge relating to diversity, infestation dynamics, and host plant range is readily available. In natural vegetation, the variety of stem borers is higher than that found in agroecosystems. However, there is a paucity of South African studies that explain the observed differences in diversity between the two systems. Stem borers are also known to exhibit species-specific ecological requirements, which influence their distribution between African countries. South African biomes are classified based on vegetation structure and climate, which happens to be the most critical factors that affect the distribution of phytophagous insects. This makes biomes an excellent model to investigate diversity and distribution of stem borer species. In this study, we investigated diversity, distribution and species composition in four biomes. The results showed that diversity and distribution of the stem borers in natural vegetation was determined by host plant distribution. Stem borer diversity correlated with high diversity of host plants. Thirty-two stem borer species were collected from 27 host plants and another three from light traps. Widely distributed host plants supported a higher diversity of stem borers, which is consistent with the resource availability hypotheses. Non-metric dimensional scale unfolding revealed disparity in host plant preference and plant species composition between the various stem borer families (Kruskal’s Stress = 0.16). Tortricidae species and Sesamia typhae (Le rü) (Noctuidae) feed exclusively on hydrophytic Cyperaceae species. The majority of Noctuidae, Crambidae and Phycitidae species collected were oligophagous on terrestrial Poaceae, with a few polyphagous exceptions feeding on hydrophytic Cyperaceae and Typhaceae. Additionally, species composition of Poaceae host plants differed between 8 Crambidae and the Phycitidae species. Stem borer species composition between biomes revealed the presence of distinct host plants (2D stress = 0.09) and stem borer (2D stress = 0.13) communities. The stem borer abundance and diversity were strongly correlated (R2 = 0.64), but species diversity (R2 = - 0.95) and host plant diversity (R2 = - 0.85) were inversely correlated to altitude. Based on these results it was concluded that stem borer diversity and distribution in natural vegetation was influenced by host plant diversity and distribution as well as climate associated with altitudinal gradients. In the last two decades, four stem borer species previously known on wild host plants; Busseola segeta (Bowden), Busseola phaia (Bowden), Pirateolea piscator (Fletcher) and Conicofrontia sesamoides (Hampson) have invaded cultivated crops. These invasions remained undetected because of a shortage of surveys, habitat transformation and misidentifications. Misidentifications are common among stem borers due to the considerable resemblance between morphospecies. In this study, we assessed the capacity of the mitochondrial gene Cytochrome c oxidase (COI) to delineate closely related species to develop monitoring and early detection of invasive species and to assess migration patterns and gene flow between the populations. The results demonstrated that COI is an effective DNA marker for species delineation and assessment of intra- and interspecific genetic relationship. The K2P distances and phylogenetic tree defined boundaries between Noctuidae species with high resolution. No divergence distance was detected between intraspecific species, but for the congener species, divergence distance was 0.044%-0.111% with an average of 0.076%. The average interspecies K2P distance (0.57%) was 5-15 times higher than the congener species distances. Phylogenetic analysis revealed the presence of two clades. Busseola and Sesamia species were connected in a monophyletic clade with a strong (93%) bootstrap. The second monophyletic clade comprised of a cluster of Pirateolea, Acrapex and Conicofrontia species, and this was also supported with 9 a strong bootstrap (100%). The gene flow study revealed low levels of genetic differentiation between the populations of B. fusca collected from different maize producing areas in South Africa. This low genetic differentiation was consistent with high gene flow. The number of effective migrants between the populations was between 8 and 99 individuals per generation. These results indicate high connectivity between the populations.
- Full Text:
- Date Issued: 2019
Effect of social capital and information acquisition on the adoption and benefits of conservation agriculture among cassava and maize smallholder farmers in South-West Nigeria
- Authors: Olawuyi, Seyi Olalekan
- Date: 2019
- Subjects: Agricultural conservation , Sustainable agriculture , Farms, Small
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15200 , vital:40200
- Description: Sustainable economic growth and development in developing economy like Nigeria is achievable through the agricultural sector and sub-sectors which are concentrated in rural areas. Rural areas represent a home to majority (about 75%) of the households practicing farming for family sustenance and/or to earn income from the sales of agricultural products (Oyakhilomen and Zibah, 2014). In addition to the persistent use of traditional farming practices, these rural farming households cultivate crops varieties that are low-yielding on small and scattered farmland holdings (smallholder farmers) (Oyakhilomen and Zibah, 2014). This act depletes the soil organic matter with devastating consequences on production output, income generation as well as the ecosystem. Similarly, non-access to agricultural credit and limited technical knowhow are parts of the challenges that are facing the development of farming activities in subSaharan Africa, including Nigeria (Kassie, Pender, Yesuf, Köhlin, Bluffstone and Mulugeta, 2008). These challenges call for holistic interventions such as conservative agricultural practices; which are sustainable, promote safe environment and ultimately increase production output.
- Full Text:
- Date Issued: 2019
Effects of pre-slaughter stress, sex and breed on blood stress indicators, heat shock proteins, glycolytic potential and lamb quality
- Authors: Stempa, Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare , Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
- Full Text:
- Date Issued: 2019
Electrical, photo-thermal and mechanical degradation analysis of degraded single junction amorphous silicon solar modules
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
Evaluating Livestock Development Programmes through the Production Risk Interface: Case of the Kaonafatso ya Dikgomo (KyD) Scheme in South Africa
- Authors: Ngarava, Saul
- Date: 2019
- Subjects: Livestock projects
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10353/15730 , vital:40513
- Description: Livestock is significant in the livelihoods of the rural poor, providing a plethora of benefits. Livestock Development Programmes (LDPs) can transform smallholder farmers’ production for increased production and poverty reduction. The Kaonafatso ya Dikgomo (KyD) Scheme is a LDP implemented in South Africa with the aim of assisting smallholder farmers to attain economic and sustainable beef production. The literature shows that most evaluations of LDPs have been quantitative based on measurable and quantifiable metrics. Furthermore, various socio-economic and institutional factors have a bearing on the decision to participate in LDPs and eventually adopting the practices. Impact assessments of LDPs have been devoid of risk consideration as well as ascertaining how risk introduced by participating in LDPs has impacted productivity. The overall objective of the study was therefore to evaluate LDPs, focussing on benefits, participation and risk. The specific objectives of the study entailed developing a conceptual tool for measuring the qualitative and secondary benefits. Secondly, it was to determine factors influencing participation decisions in the KyD Scheme. Thirdly, the study sought to measure and compare calving rate and off-take rate risk between KyD Scheme participants and non-participants. Lastly, the study highlighted the variability (risk) introduced by participating in a LDP and its impact on production. The study utilised a cross-sectional survey of KyD Scheme participants and nonparticipants in KwaZulu-Natal, Limpopo and Eastern Cape Provinces of South Africa. Non-probability convenience sampling method was utilised in selecting a sample of 164 KyD Scheme participants and 81 non-participants. A semi-structured questionnaire was the data collection tool utilised. A conceptual “Livelihood Effect Benefit Index”; Probit, Tobit and Ordered Probit models; Just and Pope Production function; Propensity Score Matching; and Monte Carlo Simulations were utilised to analyse data. Statistical Package for Social Scientists version 24, STATA 13 and @Risk Decision Tool were the analytical packages utilised in analysing the data. The study found that the Scheme provided low qualitative benefits, mainly through social capital. Furthermore, socio-economic and institutional factors have significant impact on the decision to participate in the Scheme, extent of participation and decision to continue practicing Scheme experiences. In comparing the two groups of Scheme and Scheme non-participants, calving and off-take risk for KyD Scheme participants was lower than that of Scheme non-participants. In comparing individuals with similar characteristics between the two groups, Scheme participants reduced calving risk whilst increasing the off-take risk. Page | vi The study concluded that the Scheme exhibited low qualitative benefits. Furthermore, the decisions to participate and the extent of participation in the KyD Scheme were influenced by various socio-economic and institutional factors, which were however more favourable to resource endowed smallholder farmers. In addition, the Scheme had significant impact on production risk. The risk reducing determinants appeared to also favour more resource endowed smallholder farmers who had more farming experience. The study’s recommendations were subdivided into short term, medium term and long term. The short term recommendations included targeting farmers within a distance of between 30km and 90km from a formal market, promoting dipping services-based training and extension, and providing information and training concerning calving i.e. animal health, husbandry and breed selection for herd maximization. Participation in the Scheme and the extent of participation can be improved through enhancing awareness of the Scheme at various points where stock feed are available to farmers. Furthermore, enhanced cooperation with extension workers provides a conduit in improving awareness of the Scheme and enhancing participation. The medium term recommendations pertained to initiatives such as promoting other livelihood options to enhance benefits of the programme, and promoting social capital enhancing initiatives such as mentoring and providing social capital objectives that can be integrated into the overall livestock sector strategy. The long-term recommendations include initiatives such as subsidizing increase in herd size to between 50 and 120 cattle, maintaining a monthly frequency of farmer-extension contact of between 2 and 5 times per month, as well as incorporating calving and off-take risk in policy formulation, implementation and evaluation
- Full Text:
- Date Issued: 2019
Evaluation of groundwater potential based on hybrid approach of geology, geophysics, and geoinformatics: Case study of Buffalo Catchment area, Eastern Cape, South Africa
- Authors: Owolabi,Solomon T
- Date: 2019
- Subjects: Hydrogeology Geology
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: http://hdl.handle.net/10353/12238 , vital:39218
- Description: This study focuses on the feasibility of exploring potential groundwater zones through assessment of catchment geo-hydrodynamic processes, using hydro-statistic principles and geographic information system-based approaches. The research work integrated analysis of hydrologic variables, geologic structures, and geomorpho-tectonic processes that provide information on spatial variability of hydrologic units in a watershed. The study is aimed at improving conceptual knowledge and presenting the technical feasibility of exploring potential groundwater zones through geo-hydrodynamic perspectives in hydrogeologically challenged environments. The study adopted a case design approach at the Buffalo hydrologic basin headwater in Eastern Cape, South Africa. The methods used in this study include: field mapping of geologic units and structures, digital processing of aeromagnetic map, cross-section profiling of borehole logs, auto-extraction of lineament, streamflow variability and recession assessment, geomorpho-tectonic analysis of surficial drainage pattern, vertical electrical sounding for imaging shallow subsurface layers, and geospatial integration of thematic maps of groundwater multi-influencing factors. The results indicate that the hydrogeological settings of Buffalo watershed comprised of good, moderate, fair, poor and very poor groundwater potential zones which cover 187 km2 , 338 km2 , 406 km2 , 185 km2 , and 121 km2 respectively. The results report that the groundwater system of Buffalo watershed is mainly hosted by the well-drained fractured dolerite and the shallow unconfined sandstone aquifer. The aquifer is bounded by two parallel impermeable valley walls in the north and south. Also, the Buffalo drainage system constitutes a variable head boundary as a groundwater discharge zone. The groundwater discharge which mostly occurs at the Tshoxa upper course, Mgqakwebe, Quencwe, Yellowwoods upper course and the Buffalo River center influence the status of the Buffalo River as a perennial river system. vi The groundwater recharge occurs through the networks of surficial lineaments and fractures concentrated on the sandstone lithosome, mostly in the northern half of the watershed. The surficial tectonic features trend in a WNW-ESE and E-W direction. The groundwater flow system is controlled by the subsurface lineaments which are oriented in west-northwest – eastsoutheast direction. Most of the groundwater recharge is driven by rain which is extreme at the north. The hydro-climatic pattern of the region influences the dendritic drainage system of Buffalo watershed. The geologic characterization and geomorpho-tectonic analysis indicate that the geologic settings are made up of upward-fining lithologic material and siliciclastic materials that were deposited as fill in paleochannels by braided and meandering fluvial systems. The variability in dissection property and the fluvial system indicates that Buffalo hydrologic and geomorphic systems are heterogeneous and complex. The possible impact of these variabilities aligns with the report of geoelectric sections which revealed the heterogeneity of the aquifer intrinsic properties and variability in groundwater yield. The electric resistivity tomography revealed the existence of a fault system and variation in the thickness of the aquifer. Hydrologic characterization indicates the vulnerability status of the rivers within the watershed. In particular, the Ngqokweni River is vulnerable to diminution while Quencwe River has the potential for a flash flood. Buffalo station is an important surface water capture zone. Delineation of groundwater potential zone should incorporate geologic, hydrologic, geophysical, geomorphotectonic, and environmental perspectives due to the inherent relationship among influencing factors. The study therefore identifies groundwater capture zones which can be further explored for groundwater development and to mitigate the stake of water shortage. The study therefore recommends the approach here to the department of water affairs for adoption to map the zones of groundwater potential at a regional scale. The study also provides resourceful information on vii groundwater recharge zones and therefore recommends that the environment and water stakeholders work together to protect the recharge zones from groundwater contamination due to land use
- Full Text:
- Date Issued: 2019
Evaluation of pre-treatment methods on production of bioethanol from bagasse and sugarcane trash
- Authors: Dodo, Charlie Marembo
- Date: 2019
- Subjects: Lignocellulose
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15387 , vital:40403
- Description: A variety of methods have been researched on for bioethanol preparation from different feedstocks. Amongst the available feedstock, one such feedstock is the sugarcane plant. In most of the research on bioethanol preparation with sugarcane the sugary juice has been widely used, with the bagasse and trash having been discarded as waste. The “waste” bagasse and trash are usually removed and thrown away or burnt during harvesting or in sugar mills to supplement energy requirements. This research on lignocellulosic bagasse and trash was done so as not to discard them but to rather find ways in which to use this biomass constructively. Alternatives to burning that can potentially add value to this biomass need to be researched on by evaluating their hydrolysis content. The different lignocellulose pretreatment methods of concentrated and dilute acid pretreatment, with subsequent enzyme hydrolysis as well as alkali and oxidative alkali pretreatment with enzyme hydrolysis were experimented on the bagasse and trash for hydrolysis efficiency and effectiveness. There are two types of acid hydrolysis which were investigated on which are concentrated and dilute sulphuric acid pretreatments. Use of concentrated sulphuric acid yielded the highest amounts of reducing sugars but also resulted in the highest amounts of downstream process inhibitors formation. This resulted in the need for neutralisation steps which in turn increase the overall costs of using this method to obtain reducing sugars. It has however the advantage of occurring at a faster rate, within minutes or hours, than using biological enzymes which took days, up to 72 hours to obtain the highest reducing sugar amounts. Dilute sulphuric acid pretreatment offered the advantage of using fewer chemicals which are therefore less severe on equipment and result in fewer fermentation inhibitors being formed. Dilute sulphuric acid hydrolysis also takes a relatively shorter period than biological methods of pretreatment. A challenge of fermentation inhibitors formed during acid hydrolysis was countered by using the methods of overliming (calcium hydroxide) and comparing it to neutralization with sodium hydroxide. Alkali pretreatment with sodium hydroxide was researched on by applying different pretreatment concentrations during experiments on the lignocellulosic biomass. There was an increase in the available quantities of cellulose with a significant reduction in lignin with pretreatment. Alkali pretreatment proved effective in exposing the cellulose which made v more cellulose surface area available to cellulase enzymes for enzyme hydrolysis. The highest yield of reducing sugars was obtained from hydrolysates pretreated with 0.25 M sodium hydroxide for 60 min and a period of 72 h of enzyme hydrolysis. In general the longer the pretreatment time the more reducing sugars were produced from the enzyme hydrolysis. Alkali peroxide pretreatment also resulted in significant reductions in lignin quantities of lignocellulose material. In this method sodium hydroxide in combination with hydrogen peroxide were used in pretreating the biomass. Hydrolysates with even fewer fermentation inhibitors were produced as a result. The highest percentage concentration of cellulose of 63% (g/g) was achieved after pretreatment of bagasse with 5% alkali hydrogen peroxide and trash with 0,25M sodium hydroxide pretreatment. Pretreatment of biomass using alkali with subsequent enzymatic hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) alkali peroxide pre-treated trash than 36% (g/g) for 5% (v/v) with the least inhibitors. Reducing sugar yields of 25% (g/g) and 22% (g/g) were obtained after pretreatment with concentrated and dilute acid respectively. Neutralization of the acid hydrolysates was necessary to reduce inhibitors formed with neutralisation by sodium hydroxide resulting in low dilutions and loss of fermentable sugars as unlike in the case of overliming. Subsequent steps of fermenting the reducing sugars resulting from pretreatment into bioethanol were based on using the yeast Saccharomyces cerevisae. Pretreatment hydrolysates from alkali peroxide experiments produced higher bioethanol yields of 13.7 (g/l) after enzyme hydrolysates versus 6.9 (g/l) bioethanol from dilute acid hydrolyzates. A comparison of the effects of time showed there was more bioethanol yield of 13.7 (g/l) after 72 h of fermentation with the yeast versus 7.0 (g/l) bioethanol after pretreatment for 24 h. The only drawback is the longer fermentation period which thus reduces the process and so reduces the value of the increase in yield
- Full Text:
- Date Issued: 2019
Genetic characteristics of Human Immunodeficiency Virus-1, and deter-minants of late presentation for care and Diabetes mellitus amongst newly diagnosed Human Immunodeficiency Virus positive patients in the Eastern Cape, South Africa.
- Authors: Sogbanmu, Olufunso Oladipo
- Date: 2019
- Subjects: HIV infections
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/${Handle} , vital:40495
- Description: Phylogenies may help to characterize transmission pairs, enhance contact tracing and outbreak investigations, track the origin and spread of epidemics over place and time, and to identify patterns of onward Human Immunodeficiency-Virus (HIV) transmission among risk groups. If the pattern and evolution of HIV drug resistance can be mapped, this may influence the development of guidelines in the clinical management of HIV especially with issues relating to prevalence of primary drug resistance and its impact on outcomes of present antiretroviral treatment (ART) regimen in use and the ability to trace and track the development of drug resistant strains. The roll-out of the test and treat Programme for newly diagnosed HIV infected pa-tient, seeks to identify HIV infected individuals early and to prevent morbidity and mortality associated with the late presentation for HIV care. The determination of the magnitude of ‘late presentation’ and or ‘presentation with advanced HIV disease’ can be used in very diverse settings and for many purposes. It provides a unified way to define the problem, thereby targeting appropriate interventions to prevent the detrimental outcomes associated with late presentation to care. The subtle relationship between HIV and diabetes mellitus (DM) may also help in formulating better preventive programs to aid the control of non-communicable diseases such as DM. This cross-sectional study includes a purposive selection of 335 HIV positive patients attending the voluntary counselling and Testing (VCT) and HIV Counselling and Testing (HCT) centres and outpatient departments at Cecilia Makiwane Hospital and the HCT sites at the Buffalo District municipality community health centres, Eastern Cape Province, South Africa. Late or delayed presentation of HIV infection was defined as CD4 cell count beneath 350 cells/μL and/or patients presenting with an AIDS-defining event at the first follow-up regardless of the CD4 cell count. Chapter 1 provides the general introduction had an overview of the introduction to the study, the statement of the research problem, hypothesis, the aim and the objectives. xx Chapter 2 looked in-depth at the HIV, case definition, the latest epidemiology of HIV, the HIV genome, the life cycle of HIV, its diagnosis, the classes of antiretroviral drugs, development of drug resistance. Chapter 3 highlighted the prevalence of Transmitted Drug Resistance (TDR) with focus on the protease gene. RNA was extracted from blood samples of 72 newly diagnosed HIV-1 patients attending some HIV testing and counselling clinics from August 2016 to July 2017. Protease fragments were amplified with specific primers by RT-PCR followed by nested PCR. The amplified products were sequenced using the ABI 360 sequencer, edited with Geneious version 9.1.5 and translated into amino acid with BioEdit software. Drug related resistance mutation (DRMs) analysis was performed on all the protease sequences in accordance with the 2009 WHO list of surveillance drug resistance mutations by submitting the edited sequences to Stanford HIV drug interpretation programme and the international AIDS society-USA guidelines for query of drug resistance associated mutations while phylogenetic analysis was performed using MEGA 6 to allocate all viral sequences into subtypes. In the study, a total of 52/72 (71.1%) reliable HIV-1 protease sequences were obtained in which subtyping and drug resistance mutations were performed. Two (3.8%) major Protease resistance associated mutation (V82A/L and L90M) were observed while another polymorphism like L10F, T74S, Q58E, L10I/V and M46V were also identified. Phylogenetic analyses delineated all the sequences as HIV-1 subtype C. Chapter 4 describes the prevalence and the determinants of late presentation amongst newly diagnosed HIV positive individuals in the Eastern Cape. It indicates the extent of the prevalence of patients presenting to care and at what HIV stage they were assessing health care services since the inception of the ‘test and treat’ strategy. It is a cross-sectional study where a total of 335 newly diagnosed patients were recruited consecutively be-tween August 2016 and July 2017. Late presenter for HIV care was defined in accordance with the European Late Presenter Consensus working group as a patient who reports for care when the CD4 count is below 350 cells/μL and/or when there is an established Aids- xxi defining clinical condition, irrespective of CD4 count. Adjusted and unadjusted logistic regression analysis was used to examine the determinants of late HIV diagnosis. The study showed that 60% of patients were late presenters, with 35% presenting with advanced disease. The major determinants identified were being male and low level of education. This led to recommendations directed at ensuring programmes that targets men in identifying their HIV status and assess care at early stage to prevents the morbidity and mortality associated with delayed presentation. Also, it was recommended that effort should be made to improve access to education and also include HIV related topics into the educational curriculum. Chapter 5 aimed to describe the prevalence and determinants of DM amongst newly diagnosed HIV positive individuals. This is a cross-sectional study which recruited 335 patients between August 2016 and September 2017. Definition for diabetes mellitus was made based on the SEDMSA 2015 guideline of HBA1C of above 6.5%. Adjusted and unadjusted logistic regression analysis was used to examine the determinants of abnormal glycated haemoglobin. Findings showed the prevalence of DM at about 6% amongst newly diagnosed HIV positive individuals. This is similar to findings in other study within the country, but a bit lower than what was obtained in the developed countries. The role of older age (above 40 years) as predisposing factor to development of diabetes in newly diagnosed HIV positive individual was well noted and taken. This ensures that screening for DM should be targeted at elderly HIV positive individuals. The grey area of the appropriate mode of diagnostic test to use to diagnose HIV is still debatable, however, a combination of HBA1c and fasting blood sugar (FBS) may improve the diagnosis of DM in this population group. In chapter 6, the general conclusions, recommendations and future perspectives of the study are reflected.
- Full Text:
- Date Issued: 2019
Genetic diversity, resistance profile of hiv and risk assessment of mother-to-child transmission in pregnant women on antiretroviral therapy in the Eastern Cape, South Africa
- Authors: Adeniyi, Oladele Vincent
- Date: 2019
- Subjects: Antiretroviral agents , HIV infections -- Treatment -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15120 , vital:40183
- Description: Despite the initiation of life-long ART in HIV-infected pregnant women, the rate and determinants of infant HIV transmission are not known, especially in the poor resource settings of the Eastern Cape, South Africa. Maternal anti-retroviral therapy (ART) is crucial for elimination of mother-to-child transmission (MTCT) of HIV. However, the inevitable risks of emergence of HIV drug resistance poses significant threat to achieving this goal of HIV-free generation and keeping mothers alive. Also, it is unclear if women with high viral load at delivery have acquired clinically relevant mutations, which could confer resistance to the ART, thus, further increasing the risks of motherto-child transmission of HIV-drug resistance strains. In addition to the gaps identified in the prevention of mother-to-child transmission (PMTCT) context, the understanding of regional epidemics is crucial to the broader epidemiological profiling of HIV infections in the country. Despite the rapid influx of foreign nationals to South African and Eastern Cape Province, there has not been any molecular epidemiological studies profiling the HIV diversity in the Eastern Cape.
- Full Text:
- Date Issued: 2019
Geological and geophysical assessment of groundwater vulnerability to contamination in selected general landfill sites in the Eastern Cape Province, South Africa
- Authors: Mepaiyeda, Seyi
- Date: 2019
- Subjects: Groundwater -- Pollution Sanitary landfills
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: http://hdl.handle.net/10353/12227 , vital:39217
- Description: Increasing expansion, population and urbanization have resulted in high volume of waste generated daily in South Africa. Most municipalities in the Eastern Cape are experiencing challenges in effective waste disposal, thus resulting in pollution of the air, soil and groundwater by the percolation of harmful contaminants into the environment from landfill leachate. Groundwater resources are limited in South Africa due to itssemi-arid nature. Also, there islimited information available, not only about where it occurs but how to manage it so that its quality does not depreciate to unacceptable levels. A combination of these factors coupled with a gap between waste policy and its subsequent implementation may be disastrous to South Africa. This research examines the impact of landfill sites on groundwater resources at three selected sites in the Eastern Cape Province using an integrated geological and geophysical approach. The methodology adopted include: an exhaustive literature review on waste management policies and practices in South Africa and Eastern Cape specifically. It also involved remote sensing for the study of geomorphology and structural interpretations of lineaments. Field excursions, analysis of physico-chemical and geochemical properties of groundwater obtained from monitoring boreholes and leachate pond in the vicinity of the landfill sites was also carried out. Combined induced polarization (IP) and electrical resistivity measurements for geophysical assessment of groundwater vulnerability and petrographical analysis was alos adopted. Data analysis and interpretation of the obtained results showed that the selected landfill sites are generally characterized by a 4-layer Earth structure with an average depth to top of the bedrock between 15 m - 30 m. Plant-rock association observed from the aerial photo-interpretation showed groundwater potential around the locality of the landfill sites with a dendritic to poorly drained x patterns and moderate to high topography. Structural controls such as the presence of lineaments and a fractured bedrock beneath, which are excellent pathways for the migration of leachate, particularly at the Berlin and King Williams Town landfill sites were observed. Analysis of physico-chemical and geochemical properties of water samples showed contamination of the groundwater by heavy metals and some of the physico-chemical properties were above the generally acceptable limits (WHO). These include high electrical conductivity (EC) and total dissolved solid (TDS) values observed in the groundwater samples from the King Williams Town landfill which indicated a downward transfer of leachate into the groundwater. The difference in EC and TDS values for boreholes BH2 and BH1 (9892 µS/cm, 4939 mg/L and 6988 µS/cm, 3497 mg/L respectively), showed that concentration of contaminants increased towards the centre of the landfill. Interpretation of the obtained results from the Berlin landfill showed the presence of heavy metals in groundwater samples in high concentrations. This indicated the dumping of toxic and hazardous waste substances on the landfill, contrary to the landfill design and classification. This could have harmful effect on plants and animals. Integrated geophysical assessment showed the presence of leachate plumes on pseudosections across the landfill sites. This was further corroborated on the chargeability pseudosections. Resistivity and IP pseudosections from the Berlin landfill showed a 4-layered Earth structure and anomalous zones of resistivity (≤ 112 Ώ-m) and low chargeability (≤1.25 ms) in the top layers. This is indicative of percolating leachate plume in the unsaturated zone. Contaminants ranging from unsaturated waste with high ion content to dense aqueous phase liquid contaminants, characterized by low resistivity (34 Ώm to 80 Ώ-m) and low chargeability values (0.05 ms to 5.75 ms) were identified across the Alice landfill. Results from the King Williams Town Landfill revealed plume contamination to a depth of about 75 m, well within the aquiferous zone. xi It is suggested that waste disposal practices should be improved by proper waste inspection and classification at landfills prior to disposal, use of lining and cap material to prevent leaching of contaminants into the groundwater below and the construction of waste cells and containment structures. This will go a long way in mitigating groundwater contamination due to landfilling at the study areas
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- Date Issued: 2019
Impact of adoption of drought tolerant maize varieties on yield in the face of climate change: A case of Salima, Chikwawa and Karonga districts, Malawi
- Authors: Rukasha, Conscience Tanyaradzwa
- Date: 2019
- Subjects: Climatic changes Food security Dry farming
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15628 , vital:40491
- Description: Drought is a huge limiting factor in maize production, mainly in the rain-fed agriculture of subSaharan Africa. In response to this threat, drought-tolerant (DT) maize varieties have been developed with an aim to ensure maize productivity under drought conditions. This study assessed the impact of smallholder farmers’ adoption of DT maize varieties on maize productivity. The first step into understanding the impact of adoption of these varieties on smallholder farmers’ productivity was to first identify the varieties that they were growing. To achieve this, data was collected through the means of a household survey of 600 farmers from Karonga, Chikwawa and Salima districts in Malawi. The major findings drawn were that though most of the farmers have adopted the use of hybrids, as they are fairly common among the varieties that are being grown, most of these hybrids were not drought tolerant varieties. Previous studies had concluded that most of the farmers in Malawi were still growing local varieties. Results from this study showed a major increase in the use of hybrids with SC403 being the most grown variety. The second step in the analysis of the impact of DT maize adoption was to analyse the level and intensity of adoption of these varieties among the smallholder farmers. This was done using a Double Hurdle Model. The results from the double hurdle showed that only 23% of the sampled farmers were growing one or more DT varieties on their plots. Generally, farmers’ decision to use improved agricultural technologies and the intensity of the use in a given period of time are hypothesized to be influenced by a combined effect of various factors such as household characteristics, socioeconomic and physical environments in which farmers operate. The results in this study have shown that the geographical location of farmers plays a significant role in the decision to adopt as well as off-farm income and input subsidies. In terms of intensity, the results revealed that the farmers allocated an average of 0.46 ha of their land under maize cultivation to DT varieties. The results also showed that the intensity of adoption was influenced by gender, household size, whether or not the farmer is recycling the seed and soil fertility. The next step in the study was analysing the impact that intra-seasonal weather variability had on maize productivity. This was done by using daily weather variables for the whole growing season so as to take into account evaporation, rain gaps and other intra seasonal weather limitations. The Just and Pope Production Function was used to analyse the impact of intra-seasonal weather vi variability on productivity. The results suggest that the amount and distribution of rainfall have a strong impact on the development of the maize crop and consequently the quantity harvested. From the results, there was evidence of high variability in rainfall characteristics in terms of the intraseasonal distribution which in turn translated into high variability in maize quantity harvested by the smallholder farmers in Malawi. Lastly, the Endogenous Switching Regression Model was used to analyse the impact of adoption of DT varieties on yield. The results showed that the adoption of DT varieties increases productivity. The use of counterfactual data from the Endogenous Switching Regression (ESR) allowed for an in-depth analysis of the productive implications. The results from the ESR model showed that the farm households that did not adopt, had they adopted, they would have increased their productivity. Furthermore, the results indicated that the use of DT maize varieties successfully delivered relatively less reliance on the total and net rainfall, that is, adopters managed to support their productivity in the face of changing climate while the non-adopters were adversely affected by an increase in temperature and decrease in total rainfall. Adoption of DT varieties increased output among smallholder farmers by 441.33 kg which translates to a 41% increase. Conclusively, the results from this study showed that smallholder farmers are adopting new and improved hybrids and improved OPVs and moving away from the use of local varieties. However the new varieties they are currently using are mostly not DT varieties. This is an interesting finding because the farmers when asked about their preferred traits in maize seed mentioned drought tolerance, therefore the low level of adoption points to numerous factors. These factors include lack of awareness of these varieties among smallholder farmers and unavailability of seed. The results also showed that the level of adoption was low among the farmers. With respect to productivity, this study has shown that adoption of DT varieties by smallholder farmers will increase their yield in the face of climate change
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- Date Issued: 2019
Incidence of cholera-causing and non cholera-causing pathogenic vibrio species in the river-k and two of its feeder wastewater treatment plants in the Raymond Mhlaba municipality, Eastern Cape province of South Africa
- Authors: Gcilitshana, Onele
- Date: 2019
- Subjects: Water -- Purification -- South Africa -- Eastern Cape Effluent quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15145 , vital:40190
- Description: Despite technological advances in water treatment and improved sanitation in many developing countries, acute microbial diseases still thrive and continue to distress millions of people. This is due to the high number of rural dwellers that still source water for drinking and other domestic uses from contaminated rivers. In South Africa, there have been reports on waterborne disease outbreaks, and specifically in the area understudy, two records of diarrhoeal outbreaks associated with consumption of river water were reported within the last decade. All those outbreaks and previous reports on isolation of other pathogenic bacteria within the area necessitated the conduction of this study in order to identify the potential causes of the cholera-associate diarrheal outbreaks previously reported in the area and nationally. This study was designed to assess the incidence of cholera-causing and non-cholera causing pathogens in final effluents and surface waters of the Raymond Mhlaba Local Municipality, Eastern Cape Province, South Africa. RiverK which serves as a major resource for domestic activities, agricultural practices as well as an abstraction point for a potable water treatment plant was used for this study. River-K freshwater and final effluents of its two feeder wastewater treatment plants were sampled monthly, over a twelve-month period (December 2016–November 2017). For purposes of confidentiality, the names of the wastewater treatment plants and river involved are coded in this report. A total of 108 water samples were assessed for the physicochemical parameters that influence the presence of Vibrio pathogens. For bacteriology, the membrane filtration method followed by polymerase chain reaction (PCR) was adopted to assess the incidence of cholera-causing and non-choleracausing Vibrio pathogens, as well as their virulence-associated genes from the two wastewater treatment plants and their receiving waterbody (River-K). Antibiotic susceptibility profiles of identified Vibrio species were determined using the disc diffusion method against a panel of xvi sixteen antibiotics commonly used as antimicrobial drugs of Vibrio infections. Multiple antibiotics resistance index (MARI) and phenotypes (MARP) were measured, and the existence of antibiotic resistance genes was evaluated by PCR using specific primer sets. Most of the physicochemical parameters measured (pH, TDS, temperature, salinity and DO) complied with the recommended standards for drinking water, while some fell short of the recommended limits (EC, turbidity, TSS, free chlorine). From the presumptive Vibrio isolates, 64.3% (476/740) were confirmed by PCR, with their Vibrio densities across all sampling points ranging between 0 and 2.7 × 104 CFU/100 mL, with high counts recorded in summer, hence their positive significant correlation (P< 0.01) with temperature. From the confirmed Vibrio isolates, only V. cholerae (53/476), V. mimicus (21/476) and V. parahaemolyticus (5/476) were detected. For virulence-associated genes, virulence genes homologous to V. cholerae virulence determinants, namely ompU (35%), TCP (14%), ACE (11%), ctx (7%) and HylA (4.5%) were widespread (independently) amongst the V. cholerae and V. mimicus species, while V. parahemolyticus isolates (100%) produced only the ToxR gene. Antibiogram profiling found resistance against some antibiotics such as Nalidixic acid (65%), Polymyxin B (43.8%) etc. The MAR indices ranged between 0 and 0.67 with 41.3% of the isolates recording MAR index values above 0.2. The results presented high degrees of MARPs ranging from four to eleven antimicrobials. For resistance gene detection, the SXT element was detected in 66% of the isolates, while cat1 (93%) was the most predominant, followed by aac (68%), ant (61%), with bla-V (7.1%) as the least detected gene. Findings from this study suggest that the wastewater effluents from the two wastewater treatment plants are potential sources of pathogenic Vibrio species and River-K contains a high quantity of pathogenic Vibrio species with fluctuating seasonal variations that reaffirm temperature as a strong reason for their abundance. The antibiotic-resistant Vibrio species isolated here carry a pool of virulence-associated genes and xvii antibiotic resistance genes, presenting a health threat to the communities that use it directly for domestic and irrigation purposes. In conclusion, some surface waters in the Eastern Cape Province, South Africa are widely contaminated with cholera-causing and non-cholera causing Vibrio pathogens; furthermore, some wastewater treatment plants are ineffective in adequately removing microbial contaminants and have become sources of pathogenic bacteria to their receiving waterbodie
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- Date Issued: 2019