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Factors affecting effective ecological restoration of Portulacaria afra (spekboom)-rich subtropical thicket and aboveground carbon endpoint projections

  • Authors: Van der Vyver, Marius Lodewyk
  • Date: 2018
  • Subjects: Restoration ecology , Plant conservation -- South Africa Portulacaria afra -- South Africa Shrubs -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/23250 , vital:30468
  • Description: Among the requirements to achieve effective ecological restoration on a landscape scale are a scientific underpinning, strong adaptive management and the setting of realistic endpoints. Efficacy and success depend on a complex interplay of factors of both local and regional influence. Biome-wide restoration experiments are rare, but valuable for evaluating efficacy of different protocols according to local context. The Thicket-wide Plot (TWP) experiment was initiated by the Subtropical Thicket Restoration Programme to inform landscape-scale ecological restoration of degraded Portulacaria afra (spekboom)-rich Subtropical Thicket. Thirteen different planting treatments of Portulacaria afra (spekboom) truncheons were planted as replicated rows on 0.25 ha fenced plots across the distribution range of spekboom-rich thicket habitat to better establish effective restoration protocols. I used a rule-based learning ensemble algorithm to evaluate 60 different predictors that potentially impact effective restoration, covering a range of climatic, topographic, edaphic, ecological and management related factors observed at 227 of these TWP plots. Percentage survivorship and aboveground biomass carbon sequestration rate (ABCsr) were taken as proxies for efficacy derived from subsequent monitoring data gathered 2 - 5 years after establishment, and a new allometric model I developed for spekboom. I found herbivory and identification of target habitat the two most important predictors of restoration efficacy, both well within the control of the practitioner. Highest survivorship and ABCsr were associated with larger truncheons planted deeper. The only exception to this pattern was found amongst the two smallest size truncheon categories. The application of external rooting hormone or watering treatment to truncheons were found of no significance to effective restoration, while all the pruned treatments were, in association with lesser planting depth, found to be significantly less effective than untreated truncheons planted deeper. When the restoration protocol is optimal (largest truncheons planted deepest in target habitats and protected from herbivory), my results show higher annual carbon sequestration rates (1.46 - 3.7 t C ha−1 yr−1 in aboveground biomass) than most older restoration sites that have been identified as benchmarks of success. In order to project ABC endpoints, I generated 40 new species-specific allometric models and used them to estimate biomass and carbon of intact and degraded stands on five sites spread out across the region. The highest AGC for stands in both intact and degraded states were estimated at 42.96 t Cha−1 and 12.98 t C ha−1 respectively, and the lowest at 26.32 t C ha−1 and 2.52 t C ha−1. Large canopy dominant (LCD) species contributed the largest AGC portion at three intact stands. The second largest portion was recorded for spekboom. The difference between paired stands on each sample site ranged between 23.8 and 32.8 t C ha−1, which provide a realistic target for biome-wide restoration that, when adopted together with current protocols, may be reached within three decades of inception.
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  • Date Issued: 2018

Grapple cable yarding: a productivity model for fast-growing tree plantations in Sarawak, Malaysia

  • Authors: Engelbrecht, Riaan
  • Date: 2018
  • Subjects: Tree farms -- Malaysia -- Sarawak , Forests and forestry -- Malaysia -- Sarawak Forest productivity -- Malaysia -- Sarawak
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/22049 , vital:29816
  • Description: Today, the two most important tasks faced by harvesting foresters and contractors are selecting the equipment and systems best suited to the site, and then to use this equipment in the best way possible (MacDonald, 1999). Experts estimate that the importance of tree plantations will continue to grow and that by 2050 75 per cent of the global fibre supply will be sourced from dedicated plantations (Ragauskas et al., 2006). To meet this growing demand plantations will most likely expand to steep slopes due to the priority given to agricultural and urban development, on flat land. New technological advancements in both cable yarding and ground-based harvesting systems has to a certain extent provided forest engineers with more options to choose from. Whether considering these options individually or in combination, they will have to make good choices in order to realise the full potential of forest plantations. One of the most promising techniques consist of an excavator-based unguyed yarder equipped with a new radio-controlled grapple carriage, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic and removes operators from positions of high risk. This long-term study was conducted on 12 different teams equipped with the new technology, operating in the fast-growing Acacia mangium plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 yarding cycles - each recorded individually. This large data pool allowed for the development of robust models for system production, utilization and availability estimated respectively at: 63 m3 per productive machine hour (excluding all delays), 63 per cent and 93 per cent. The study also determined the effects of yarder type and team competence on productivity and utilization. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, which accounted for 50 per cent of the total variability in the dataset and was validated with a non-significant error estimated at less than 1 per cent. The models reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations. While gained specifically on one yarder make (Alpine Yarder) and a specific plantation type (Acacia mangium), the information in this study can be extended to other similar machines and plantations, because the sheer volume of data allows cautious generalization. The teachings of kaizen, which suggest small-step work improvements, was adopted in order to propose the process of possible improvements, by combining elements of other harvesting systems as shown in Figure 1 below (Vorn Industries, 2017). Forestry is essentially a problem of transportation (Schenck, 1911) and the efficiency of such a transportation system will ultimately be determined by technology developments which drive system productivity (Ger & Klvac, 2014). Therefore, when we talk about systems for the future we should view them not as predictions or as prescriptions but as options that may be selected or rejected (Wood, 1979).
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  • Date Issued: 2018

Habitat use of important juvenile fish species in temperate Earnestine nursery areas with notes on feeding ecology and historical shifts to assist with conservation planning, South Africa

  • Authors: Nel, Larize
  • Date: 2018
  • Subjects: Mariculture -- South Africa , Fishes -- Ecology -- South Africa Fishes -- Food -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/32904 , vital:32396
  • Description: Estuaries are among the most productive ecosystems worldwide as they provide important refuge and feeding areas for the juveniles of many marine species, many of which have recreational importance. The use of these nursery areas by juvenile fishes in South Africa are in need of further investigation and many critical areas such as shallow water creeks and vegetated habitats remain understudied. By using mixed-methods, estuarine fish assemblages were assessed in five permanently open estuaries in the Eastern Cape Province of South Africa. A total of 81 428 comprising 24 families and 40 species of fishes were sampled by means of a 50 m seine net (12 mm mesh) along the length of these systems that comprised of six equidistant sites during the summer recruitment period (October - December) of 2014 and 2015. A higher catch per unit effort (CPUE) was recorded in 2014 (68 875) compared to the following year where a decline of approximately 82% was observed in the catch (12 553) for all estuaries except the Kromme Estuary. Catches were mainly dominated by the marine estuarine dependent sparid, Rhabdosargus holubi and the solely estuarine clupeid, Gilchristella aestuaria. Species compositions and catch abundance with regards to historical catches showed that the abundance of many marine estuarine dependent juveniles as well as important recreational species have declined within these systems and are mainly attributed to marine overfishing and the exploitation of undersized individuals in estuarine nurseries. Juvenile fishes that occur in these estuaries utilize a range of vegetated habitats ranging from salt marsh creeks, Zostera capensis beds, Spartina maritima and previously unexplored Phragmites australis areas. Sampling was achieved by using passive, double-winged, six-hooped fyke nets, 1 mm mesh size that was secured in placed on the nocturnal flood tide at each inundated vegetated and adjacent unvegetated habitat types. Higher catches were frequently recorded in vegetated areas for solely estuarine and marine estuarine dependent species and supports evidence of plasticity within these habitats. In general, the previously unstudied reed, P. australis showed the highest species richness and abundance of juvenile fishes overall, followed by, Z. capensis and the intertidal salt marsh species, S. maritima. These findings relate to many international trends on the value of vegetated areas as refugia for young fishes in estuaries. Fishes were also showing evidence of feeding and sheltering in these areas. By using conventional stomach contents and stable isotope methods (δ13C and δ15N signatures) on the abundant R. holubi in previously selected vegetation sites, it was clear that this species has a significant reliance on any of these habitats as their diets was largely comprised of a mixture of epiphytic algae and aquatic macrophytes. In addition, the diet of larger individuals (>80 mm) showed a greater component of invertebrates in previously unexplored habitats, which proves their omnivorous diet related to ontogenetic niche use. Knowledge of fine-scale habitat use by fishes is essential for conservation planning as exclusion zones can be optimised to limit anthropogenic influence on nursery use patterns in fishes. The availability of shallow water habitats (<60 cm) was assessed as an additional driver to explain the species diversity and richness of juvenile fishes within the lower reaches. These habitats are known as important nursery habitats providing numerous marine and estuarine spawned fishes with adequate refuge and food supply. This shallow water volume was measured by means of a two-man kayak using both the spring high and low tides in the lower reaches of these systems to assess juvenile assemblages. It was clear from the results that aquatic vegetation significantly adds to the volume of these areas and as a result, much greater fish density and species richness were observed. Generalized additive models showed that marine spawned species were particularly reliant on the availability of this shallow water along with submerged vegetation and additional environmental variables. The presence of structurally submerged vegetation typically characterized within shallow estuarine waters is commonly believed to reduce predation risk resulting in elevated densities of biota. Based on the current stock status and percentage of pristine breeding stock, five fish species classified as collapsed/overexploited was consistently found within these systems with an additional 14 species currently classified as exploited/vulnerable. Based on the current species richness and diversity, available habitat cover and knowledge regarding important recreational species, priority areas that require some form of legal protection in order to meet potential biodiversity targets, could be identified. It is a legal requirement in South Africa that all estuaries require management plans that should be based on good knowledge of priority habitats for fauna and flora. The identification of estuarine protected areas is seen as a mechanism for protecting a representative sample of the biodiversity accompanied by a complete range of environmental gradients and habitat types at a reasonable scale in order to maximize the protection of estuarine species.
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  • Date Issued: 2018

Health and activity monitoring to support the self-management of chronic diseases of lifestyle using smart devices

  • Authors: Mujuru, George Tungamirai
  • Date: 2018
  • Subjects: Computer vision in medicine , Self-care, Health Chronic diseases
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/33076 , vital:32516
  • Description: Chronic diseases of lifestyle (CDLs) are non-infectious medical conditions, such as diabetes, cardiovascular disease and cancer. These conditions are the second leading cause of death and disease in Africa. Failure to modify primary risk factors, such as an unhealthy diet, lack of physical activity and tobacco use, can give rise to intermediate risk factors such as hypertension and obesity, which predispose individuals to CDLs. The aim of the research was to investigate the use of smart devices to facilitate the self-management of health and health behaviours. The Health Action Process Approach (HAPA) model of health behaviour change was adopted, which focuses on the correction of modifiable risk factors. Two smart devices were selected, namely the Fitbit Charge 2 and Fitbit Aria, which monitor specific physiological information. The Fitbit Charge 2 can determine health activity, and the Fitbit Aria can determine the weight, body mass index (BMI) and body fat percentage of an individual. A field study was conducted with 22 participants (11 males and 11 females) to evaluate and determine the effectiveness of the smart devices. The participants were sampled from Nelson Mandela University staff and were aged between 30 and 60 years of age. The field study was conducted over two weeks in two one-week long phases. The first phase was used to obtain subjective data (using a lifestyle questionnaire), and objective health data (collected by the smart devices) from the participants. The purpose of the first phase was to form intentions. The second phase was the goal setting phase, where each participant was assisted in setting manageable personal goals. The results show that the smart devices used in the research could be used to provide motivation and monitor health data to support self-management of CDLs. The use of these smart devices was included in an updated HAPA model.
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  • Date Issued: 2018

Hydrochemical assessment of mine water discharging into the surface and groundwater systems that flow through the Cradle of Humankind World Heritage Site, South Africa

  • Authors: Long, Chazanne Anita
  • Date: 2018
  • Subjects: Cradle of Humankind World Heritage Site (South Africa) , Environmental chemistry Mine water -- South Africa Acid mine drainage -- South Africa Geochemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/30928 , vital:31225
  • Description: The UNESCO site known as the Cradle of Humankind World Heritage Site (COH WHS) is a globally important cultural heritage area that hosts some of the oldest discovered hominid fossils and is a major contributor to our understanding of the evolution of modern hominids over the past 3.5 million years. The area is locally referred to as the Cradle of Humankind that flanks a densely populated region in South Africa, and which hosts a large sector of the Witwatersrand Basin, known as the West Rand. The Witwatersrand Basin contains the world’s largest gold deposits, some of which have been mined for more than 130 years. This study characterises the West Rand mine drainage to determine the extent of the hydrochemical interaction within the COH WHS and beyond. The hydrochemistry of surface waters was analysed across a sub-catchment draining the West Rand, using standard q-ICPMS and IC techniques. A total of 32 samples were collected quarterly for an annual cycle during 2011 to 2012. The median data were used for standard hydrochemical classifications for surface waters and two mine water classification systems. This is the first time this type of quantitative and comparative study has been performed in South Africa. The results of these classifications show that the mine drainage generated from the West Rand Goldfield can be described as an acidic (pH = 3.19 to 3.36), highly metalliferous (ΣMetals = 2564 to 3 141 μg/L) mine drainage, and with (SO42- = 3217 to 3532 mg/L) and (TDScalc = 3217 to 3536 mg/L). This mine drainage has been allowed to discharge continuously into the environment for fifteen years following the flooding of the mine voids in 2002. The extent of the mine drainage signature was determined to flow through the southern portion of the COH WHS and into the Crocodile River up to 54.2 km (CA24) downstream of the point source from Randfontein Estates mine property in the West Goldfield. In addition to the surficial contamination, there is evidence of groundwater – surface water interactions within the karstic terrain of the COH WHS. The findings highlight the need for on-going monitoring and further research to determine the possible consequences that acidic mine drainage discharge has on the environment and on the yet undiscovered fossils within the cave systems of the COH WHS. The GARD and Ficklin mine water classifications are used and compared in this thesis. A single universal hydrochemical classification system, capable of becoming a globally robust and standardised approach for mine waters is a valuable contribution that is needed within this field of study, along with the inclusion of uncertainty presented graphically in a clear and unambiguous way. Research is needed to provide realistic solutions that can be implemented to mitigate potential negative outcomes identified and that are in-line with national and global legislation to preserve and protect this world heritage area. The study has implications for mine water legislation and monitoring in areas of active and historic mining, and for water resource management.
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  • Date Issued: 2018

Improving the exhaust pigment dyeing of cotton garments

  • Authors: Harilal, Shantha
  • Date: 2018
  • Subjects: Dyes and dyeing -- Textile fibers , Dyes and dyeing -- Chemistry Textile fabrics -- Coloring Textile fabrics Cotton -- Coloring
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/22231 , vital:29895
  • Description: Due to the rapid changes in fashion trends, garment dyeing is gaining popularity because of its quick response time and reduced costs, especially when dyeing with pigments. However, a drawback of pigment dyeing of cotton garments is the problem of unlevel dyeing and poor wet fastness, together with the high amount of staining of the dyeing equipment. This research has focused on investigating the effects of varying dyeing parameters on the colour strength and fastness of exhaust pigment dyed cotton garments, with the ultimate aim to improve colour strength, wet rub fastness and wash fastness; as well as try to reduce the amount of staining of the equipment, and in so doing reducing production and effluent treatment costs. The research was undertaken at a textile company, Spectrum Textiles (Pty) Ltd, which has been experiencing problems with poor wet fastness, unlevel dyeing and high staining of equipment for both knitted and woven cotton garments. Trials on knitted and woven garments were carried out in which the effects of the concentrations of the cationising agent, pigment and binder/fixer, on colour strength and dye fastness were investigated, as was also the effects of temperature, pH, material-to-liquor ratio and process route. The dyed fabrics were analysed in terms of colour strength, wash fastness and wet and dry rub fastness. It was found that, in general, increasing the amount of cationising agent, pigment, binder/fixer, pH, temperature and material-to-liquor ratio decreased the colour strength (K/S), with applying the binder/fixer prior to pigmenting mostly producing a higher K/S than when applying the binder/fixer after pigmenting. Furthermore, the use of a fixer achieved higher K/S values than when the binder was used. By the selection of the correct chemical levels and dyeing conditions, level pigment dyeing of cotton garments, with high colour strength, was achieved with Grey Scale ratings of 4 or higher for all the fastness criteria. A single optimum dyeing combination, which produced a high K/S and a Grey Scale rating of 4 or higher for wash fastness and wet and dry rub fastness, was derived.
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  • Date Issued: 2018

Improving understanding of the ecology of Indo-pacific bottlenose dolphins (tursiops aduncus) in Algoa Bay, South Africa

  • Authors: Shaanika, Titus Mwiitantandje
  • Date: 2018
  • Subjects: Bottlenose dolphin -- South Africa -- Port Elizabeth , Bottlenose dolphin -- Ecology -- South Africa -- Port Elizabeth Dolphins -- Ecology -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/34788 , vital:33451
  • Description: Site fidelity and spatial distribution of Indo-Pacific bottlenose dolphins (Tursiops aduncus) were assesed using mark-recapture from opportunistic photographs collected between June 2008-May 2011 in Algoa Bay, South Africa. Over 10 000 photographs were collected, and assessed, resulting in 2472 photographs being catalogued and analysed. In total, 2002 individual dolphins were photographically identified. The discovery curve does not reach a plateau, indicating a large, open population, as a result, the re-sighting rate over the study period was low. 178 (8.9%) animals were re-sighted, and 32 animals these were seen three times or more. The individual which was re-sighted most often was sighted five times. The residency index averaged 0.05 and reached a maximum at 0.25. 41% of the data were collected in 2009, which skewed the identifications per unit effort (IDsPUE) across years (Kruskal-Wallis Anova, KW= 11.59 n=60, p= 0.009) and seasons (KW= 17.47, n= 60, p=0.007). Due to the relatively higher data collection in 2009, identifications across years (KW=13.29, n=60, P= 0.004) and across seasons (KW=17.81 n=60, P=0.007) also differed significantly. In contrast, there was no significant difference is re-sighting across years (KW = 6.9, n=56, p= 0.8) and seasons (KW=12.26, n=56, p=0.6). The association between the 32 individuals seen three times or more was measured using the Half Weight Index, the index ranged from 0 to 1. A dendrogram revealed two social clusters consisting of 23 and 8 animals each, with one individual having no associations. Xenobalanus was recorded on all but five surveys over the study period. Xenobalanus occurrence did not significantly differ across years (KW=1.49, n=42, p=0.68) and seasons (KW= 6.59, n=43, p=0.36). Dolphins were mostly sighted in depths of <15 metres all around the bay. Travelling (36%) behaviour was the most recorded, followed by feeding (29 %), socialising (15%), milling (11 %), Slow travel (6%), resting (2%) and fast travelling (1%). Other than milling the spatial distribution of all behaviours were similar to the general spatial distribution of sightings. The project provides information that can be used for further research and conservation management of T. aduncus. Photographs used in this project were opportunistically collected, which has resulted in the underestimation of photo-identified individuals and consequently results of this project.
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  • Date Issued: 2018

In vivo toxicological evaluation of peptide conjugated gold nanoparticles for potential application in colorectal cancer diagnosis

  • Authors: Adewale, Olusola Bolaji
  • Date: 2018
  • Subjects: Nanostructured materials -- Toxicology , Colon (Anatomy) -- Cancer Rectum -- Cancer
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/50133 , vital:42050
  • Description: Colorectal cancer (CRC) is among the leading cause of cancer-related deaths in South Africa and worldwide. Efforts are being made at finding improved diagnostic tools, as early detection (before metastasis) is a major factor in CRC treatment. Colonoscopy is the most reliable detection method, but is a specialised and expensive procedure, which is invasive, not readily available and not patient-friendly. There is a risk of developing interval cancers, as colonoscopies are performed every 10 years after the age of 40. The development of non-invasive, cost efficient and readily available diagnostic tools to CRC, which can be performed at more regular intervals, using tumour-targeting molecular imaging agents, is of urgent attention. Gold nanoparticles (AuNPs) possess several physicochemical properties, including ease of synthesis, biocompatibility, and the ability to be conjugated by ligands or biomolecules such as polyethylene glycol (PEG) and peptides for improved stability, tissue targeting and selectivity. These factors potentiate the role in biomedical applications, including cancer theranostics. Conjugation of AuNPs with a targeting molecule (e.g. antibody or peptide) is directed against cancer cell receptors. The peptides, p.C, p.L, and p.14, bind to CRC cells in vitro. Conjugation of AuNPs with these peptides should be investigated for CRC diagnosis in vivo, as it is hypothesised to allow examinations at shorter intervals through imaging techniques. This could reduce the risk of interval cancers, but before developing this novel tool, in vivo toxicity evaluations are essential. This study was therefore aimed at investigating the short- and long-term toxicological effects of a single intravenous injection of peptides (p.C, p.L, and p.14) conjugated to AuNPs in a healthy rat model. Citrate-capped AuNPs were synthesised by the citrate-reduction method, and conjugated with each peptide (biotinylated) using a combination of PEG (99% PEG-OH and 1% PEG-biotin) as a stabilising agent and linker, via biotin-streptavidin interaction. Healthy male Wistar rats were intravenously injected with 14 nm citrate-AuNPs, PEG-, p.C-PEG, p.L-PEG, and p.14-PEG-AuNPs (100 μg/kg body weight), and the control rats were injected with phosphate buffered saline. The animals were monitored for behavioural, physiological, biochemical, haematological and histological changes, as well as inflammatory responses. Phase 1 rats were sacrificed 2 weeks post-injection to determine the immediate or acute toxicity of the AuNPs, while phase 2 animals were sacrificed 12 weeks post-injection, to investigate the delayed or persistence toxicity of the AuNPs. Results revealed no significant toxicities with the citrate, PEG-, p.C-PEG and p.14-PEG-AuNPs over 12 weeks post-exposure, as evidenced by biochemical assays such as serum marker enzymes, liver and kidney function markers, and cholestatic indicators; haematological parameters; oxidative stress markers; and histopathological examinations. P.L-PEG-AuNPs, however, caused significant toxicity (p<0.05) to rats, as evidenced by increased relative liver weight, increased malondialdehyde levels, and total white blood cell counts 2 weeks post-exposure when compared to the control group. This was, however, reversed during the 12 weeks post-exposure. Further, there were no evidence of inflammatory responses, using pro-inflammatory markers including phospho interleukin 18 (IL-18) and interferon-γ (IFN-γ), as indicated by immunohistochemical staining of the liver, spleen, kidney and colon of rats 2 weeks post-injection of AuNPs. Citrate, PEG-, p.C-PEG, and p.14-PEG-AuNPs did not induce immediate, acute or persistent toxicity, while p.L-PEG-AuNPs induced a transient acute toxicity. It can be concluded that 14 nm spherical citrate-AuNPs at 100 μg/kg body weight is a good candidate for biomedical applications, and as a suitable carrier for diagnostic and/or therapeutic molecules. Combination of 99% PEG-OH and 1% PEG-biotin is an appropriate option for stabilising AuNPs in biological environment, and conjugating secondary diagnostic or therapeutic biomolecules or agents to citrate-capped AuNPs. Peptide-conjugated AuNPs are suitable for the development into a diagnostic tool for CRC in vivo.
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  • Date Issued: 2018

Incidence of bacterial infections and colonisation in patients admitted to a tuberculosis hospital

  • Authors: Annear, Dale John
  • Date: 2018
  • Subjects: Medical microbiology , Microbiology Bacteriology Tuberculosis -- Hospitals -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/21482 , vital:29526
  • Description: Patients with drug resistant tuberculosis (TB) are treated with multiple antibiotics including moxifloxacin, linezolid, and meropenem, which puts them at greater risk for colonisation by multi-drug resistant (MDR) bacteria. The objectives of this study were to: (i) assess the antimicrobial prescribing patterns practiced within the hospital by retrospective patient file review; (ii) determine the spectrum of bacterial colonisation in TB patients upon admission and during hospitalisation; (iii) identify bacterial isolates and evaluate antimicrobial susceptibility profiles; (iv) detect antimicrobial resistance genes in the bacterial isolates by PCR and DNA sequencing; and (v) investigate genetic relatedness of Klebsiella pneumoniae isolates using Multi Locus Sequence Typing. Nasal, groin and rectal swabs [for the detection of extended spectrum beta lactamases (EBSLs), carbapenem-resistant Enterobacteriaceae (CRE), vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA)] were analysed from a cohort of patients (n=37) admitted either from the community (n = 28) or from other healthcare facilities (n=9) to a TB hospital. Swab samples were collected at admission and at four week intervals thereafter during hospitalization. Identification and antimicrobial susceptibility testing of bacterial isolates (n=62) were determined at the National Health Laboratory Services (NHLS) by the VITEK-MS and Vitek 2 systems respectively. Additional antimicrobial susceptibility testing was conducted by Sensititre Gram Negative Xtra (GNFX2) MIC plates. PCR and DNA sequencing were used for detection of resistance genes. Patients (n=13/37; 35%) were colonized by MDR bacteria (ESBLs [n=11], MRSA [n=2]) on admission. Colonization rates were lower in patients admitted from the community (9/28; 32%) compared to those transferred from other healthcare facilities (4/9; 44%). All admitted patients who did not exhibit colonization at baseline and who were resident within the hospital for longer than 4 weeks (17/37; 46% of total patients) became colonised by an ESBL-producing Enterobacteriaceae species. No patients acquired MRSA during hospitalisation. Among ESBL Enterobacteriaceae, Escherichia coli (41/62; 66%) and K. pneumoniae [14/62; 23%]) predominated. Nineteen percent (7/37) of patients demised during their hospitalization. Both the Vitek system and Sensititre Gram Negative Xtra (GNFX2) MIC plates susceptibilities were similar for most antimicrobials, however there were discrepancies for tigecycline susceptibility profiles. A high number of isolates exhibited resistance to aminoglycosides and fluoroquinolones. Genes encoding for ESBLs (CTX-M-14, CTX-M-15, SHV-28, OXA-1, and OXY-2-9) were detected among ESBL Enterobacteriaceae. Two Enterobacteriaceae isolates with reduced carbapenem susceptibility did not contain carbapenemase-encoding genes. MLST revealed unique sequence types and genetic diversity among the K. pneumoniae isolates from hospitalised patients. However, the source and colonization routes of these isolates could not be determined, which requires further investigation. This study provides insight into the spectrum of bacterial pathogen colonisation in hospitalised TB patients and suggests a review of infection control programs and practices at the TB hospital.
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  • Date Issued: 2018

Index optimisation for structural equation models (SEM)

  • Authors: Stindt, Carmen
  • Date: 2018
  • Subjects: Structural equation modelling
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10948/17919 , vital:28518
  • Description: Structural equation modelling (SEM), a statistical technique used extensively in quantitative marketing research and other domains, is an analytical approach used to model latent (unobservable) variables. Unlike distribution fitting where simple chi-squared goodness-of-fit assessment yields satisfactory results, model fit in SEM is more difficult. Descriptive goodness-of-fit indices have been developed over the past 50 years to assist in the assessment of model fit. The traditional assessment method requires reporting multiple indices, all of which should reflect an adequate model fit in order for the overall model fit to be deemed good. The choice of indices to report are left to the researcher’s discretion, leading to the indices used to differ considerably. The combination of using the traditional assessment method and differing indices often lead to conflicting results. This study proposes a composite index, combining frequently used indicators in an attempt to obtain a single index method for assessing model fit in SEM that performs better when compared to the traditional assessment method. Composite indices have been used in other domains as an improved method of assessing performance (Barr and Kantor, 2004). The composite index proposed is evaluated using a Monte Carlo simulation study under different experimental conditions. The experimental conditions investigated are sample size, estimation method and model misspecification. These experimental conditions are chosen to investigate as each has been shown to affect the traditional indices performances. The ideal fit indices should be able to detect model misspecification while being insensitive to sample size and estimation methods. This is not always the case with the traditional indices. The composite index proposed is shown to outperform the traditional assessment method under many of the experimental condition combinations. This provides evidence that composite indices may be a more beneficial method of assessing model fit in SEM.
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  • Date Issued: 2018

Investigating long-term host-parasite dynamics in odontocetes in Southern Africa

  • Authors: Adams, Inge Alison
  • Date: 2018
  • Subjects: Biological invasions -- Environmental aspects , Cetacea -- Indian Ocean , Ecological disturbances
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/23437 , vital:30543
  • Description: Cetaceans are a very diverse family and globally, various aspects about their biology have been studied, including infection by parasites. Twenty-five dolphin species can be found in the South African subregion and very little information is available detailing which parasites are infecting them. Parasite samples have been collected opportunistically since the 1970’s from dolphins incidentally caught in shark nets off the KwaZulu-Natal coastline as well as from dolphins stranded along the Eastern Cape coastline. These samples have been stored in the Graham Ross Marine Mammal Collection at the Port Elizabeth Museum and samples belonging to eight odontocete species have been used in the present analysis. These eight species are: the Indian Ocean Humpback Dolphin (Sousa plumbea), the Indo-Pacific Bottlenose Dolphin (Tursiops aduncus), the Long-beaked Common Dolphin (Delphinus capensis), the Risso’s Dolphin (Grampus griseus), the Pantropical Spotted Dolphin (Stenella attenuata), the Striped Dolphin (Stenella coeruleoalba), the Pygmy Sperm Whale (Kogia breviceps) and the Dwarf Sperm Whale (Kogia breviceps). This study aims to investigate which parasites are infecting odontocetes in Southern Africa. Secondly, this study aims to investigate whether any trends in infection exist between sexes, age groups, cause of death and over time. Eighteen parasite species were found to infect odontocetes in Southern Africa. Two could only be identified to family level, seven to genus level and eight to species level. Only one parasite, a trematode, could not be identified and several parasite species were new host records for the subregion. Results showed that the prevalence of parasitic infection has increased over the last four decades, prompting questions regarding the health of our oceans. This study is the first to comprehensively investigate which parasite species are found in these eight odontocete species in Southern Africa. This baseline data will contribute greatly to other types of research involving parasites and provides us with information regarding the health of our ocean.
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  • Date Issued: 2018

Investigation of the potential separation of isomers and related compounds using host compound (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol

  • Authors: Pohl, Pieter Lourens
  • Date: 2018
  • Subjects: Chemistry, Organic , Clathrate compounds Thermal analysis
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/23131 , vital:30432
  • Description: In this study, we investigated the potential of a host compound, (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT), for use in the separation of isomers and related compounds using host-guest chemistry. The title molecule, DMT, is composed of a butane chain bearing hydroxyl moieties on the terminal carbons and methoxy moieties on the two internal, chiral carbon atoms. In addition, there are two phenyl rings on each of the terminal carbons. The synthesis of DMT was carried out by subjecting the diester of naturally-occurring optically active tartaric acid to a Grignard reaction employing phenylmagnesium bromide. Subsequent methylation of the secondary hydroxy groups with dimethyl sulfate afforded DMT. The resulting host molecule was investigated for its inclusion abilities by crystallizing with a number of potential aromatic, aliphatic and alicyclic guests such as toluene, aniline, nitrobenzene, anisole, cyclohexane, ethyl acetate and ethanol. Host:guest ratios were determined by means of 1H-NMR spectroscopy. Of the hosts investigated, DMT favoured a host:guest ratio of 2:1 for all included guests investigated. It complexed with most non-polycyclic aromatic guests as well as cyclohexane, cyclohexene and cyclohexanone. It was not able to include short chain or branched alcohols such as methanol, ethanol or 2-propanol, or other hetero-aliphatic or hetero- cyclic compounds such as diethyl ether, acetonitrile, morpholine or dioxane. Competition inclusion experiments were performed in which DMT was crystallized from equimolar and non-equimolar binary, ternary and quaternary mixtures of appropriate guests. The mother liquor mixtures and resultant crystals were subjected to GC-MS analysis in order to determine whether DMT showed discriminatory behaviour towards the guests from a mixture. It was observed that DMT was able to differentiate between related compounds, for example, the host preferred to include N,N-dimethylaniline compared with N-methylaniline and aniline. The host also discriminated against isomers, for example, p-xylene was preferentially included over o-xylene and m-xylene, while o-cresol was included in preference to p-cresol and m-cresol. Single crystal X-ray analysis was used to investigate the host–guest interactions responsible for guest inclusion, as well as to discern reasons for the host’s selective behaviour. X-ray data for the inclusion complexes indicated that each complex was isostructural, crystallizing in the monoclinic C2 crystal system. A pair of 1,3- and 2,4- intramolecular hydrogen bonds, as well as intramolecular non-classic hydrogen bonds between adjacent ortho-aromatic hydrogens and hydroxy moieties was a significant stabilizing factor for the geometry of the host. Guests were held within discrete cavities in the crystal lattice, and experienced only π–π stacking, CH–π interactions and other short contacts. Thermal analyses were used to determine the relative thermal stabilities of the complexes, and these data compared to the selectivity preference of DMT, obtained from the competition experiments, in order to assess the reasons for any discriminatory behaviour. Finally, Hirshfeld surface analysis data was used to determine if the thermal stability of the complexes was related to the number and type of interactions between host and guest.
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  • Date Issued: 2018

Investigation of the thermo-chemical behaviour of coal-algae agglomerates

  • Authors: Baloyi, Hope
  • Date: 2018
  • Subjects: Biomass energy , Coal -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/23913 , vital:30642
  • Description: There is a growing research interest in the co-processing of biomass and coal, with the aim of addressing the negative attributes associated with the thermal processing of coal alone. Biomass feedstocks are regarded as a clean, renewable source, and the co-utilization of biomass feedstocks with coal is deemed to have a potential to reduce emission of pollutants (i.e. NOx and SOx) and volatile organic compounds (VOC’s). Moreover, biomass are thermally reactive and thus facilitate the conversion of coal during co-processing. Biomass material and coal are two autonomous fuel materials with different chemical characteristics and have a dissimilar thermal behaviour making it difficult to achieve chemical interaction between the two solid fuels to contribute to the formation of products. Coalgae® Technology developed at the Nelson Mandela University, involves the biological treatment of coal fines by adsorbing live microalgae biomass (in slurry form) onto waste coal fines to form coal-microalgae agglomerates. This new innovative approach seeks to integrate bio-based feedstock into coal thermal processing and to improve the utilization and thermal efficiency of coal fines as well as the interaction between the volatile components of biomass and coal during thermal processing (e.g. devolatilization), thereby overcoming some of the challenges that confront the co-processing of coal and biomass. Coal fines are low-ranked coals, generally characterized by high contents of sulphur, high ash yields, low calorific values and poor thermal reactivity, and these attributes limits the thermo-chemical processing of the coal fines. Therefore, this investigation was undertaken to assess the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorbing live microalgae slurry at varying ratios onto coal fines. For this purpose, the effects of adsorbing microalgae at varying ratios on the chemical characteristics and thermal behaviour of coal fines under pyrolytic conditions were investigated. The primary aim was to assess whether the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorption of live microalgae onto fine coal, is substantively modified compared to a simple additive model of the original coal and pre-dried microalgae biomass samples. Results obtained from the proximate analyses performed on an Eltra Thermo-gravimetric analyzer (TGA) thermostep, have shown that the adsorption of microalgae slurry onto coal fines does not possess greater influence in improving the yield of volatiles and ash in coal fines than can be expected from a simple additive model of the original raw materials. Based on the ultimate analyses results, it was found that the adsorption of microalgae slurry resulted in a systematic reduction in the sulphur content, a notable increase in the hydrogen and oxygen contents, however, no significant disparities were found between the measured ultimate properties of coal-microalgae agglomerates as compared to the theoretically-expected ultimate properties from a simple linear combination of parental coal and microalgae biomass. Assessment of the thermal behaviour of parental samples and coal-microalgae agglomerates involved the use non-isothermal (40-900ºC, 20 K/min) thermogravimetry under inert conditions. It was found that the adsorption of microalgae slurry onto coal fines resulted in an improved thermal reactivity of coal fines, although, did not affect the overall pyrolysis characteristics of the coal fines. Comparison of the thermal profiles (measured and calculated TG/DTG curves), revealed that the yield of volatile products during the pyrolysis of coal-microalgae blends do not exceed the expected volatile yields from a simple combination of coal and microalgae biomass. These results suggest that there was no positive or accelerative synergistic interaction between volatile components of adsorbed microalgae and coal fines during pyrolysis. Mild pyrolysis of raw coal and coal-microalgae performed in a fixed-bed reactor furnace (450ºC), resulted in improved yields of Fossil-Bio crude (FBC) oil (derived from coal-microalgae pyrolysis), at increased biomass ratio compared to coal tar. FBC Oil was found to contain relatively high contents of oxygen, hydrogen, and low sulphur content than coal tar. GC-MS analyses showed the presence of a heterocyclic compounds (i.e. Indole and 2, 6 dimethyl pyridine) in the FBC oil and these were not identified in the coal tar. Furthermore, high boiling compounds such as Flourene, pyrene and pentacosane were identified in the coal tar, however not identified in the FBC oil. Simulated distillation results showed notable differences between the FBC oil and coal tar in terms of the distribution of boiling point fractions particularly, high boing point components. Semi-devolatilized chars derived from coal-microalgae agglomerates showed substantial degree of decarboxylation and dehydrogenation compared to the coal chars.
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  • Date Issued: 2018

Linking people’s needs, preferences and values to ecosystem services provided by marine phytoplankton of Algoa Bay, South Africa

  • Authors: Snow, Bernadette
  • Date: 2018
  • Subjects: Marine phytoplankton -- South Africa -- Port Elizabeth , Marine biology -- Research Biodiversity conservation -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/33363 , vital:32669
  • Description: Marine, coastal and ocean development has gained impetus around the globe and in particular along Africa’s coastal states. A socio-ecological systems framework approach was adopted to explore marine and coastal socio-ecological systems in Algoa Bay, situated in the Eastern Cape, South Africa a Bay with a rich history steeped in culture and diversity. Phytoplankton biodiversity was determined for the Bay to characterise aspects of the marine environment in Algoa Bay. The policy landscape for South Africa was also analysed to characterise the governance landscape and identify if the policies, legislation and frameworks adopted and applied would support socio-ecological systems thinking and support equitable development of marine and coastal resources. Positives raised by manager are the general positive attitude and pro-environmental value system. To understand how people within the Nelson Mandela Bay Municipality value the marine and coastal environment, their knowledge of phytoplankton and services provided, governance knowledge, attitudes towards the future of the socio-environment landscape and value positions that would identify pro-environmental behaviour of the communities surveyed. Loss of marine and coastal environments and services would be a direct threat to spiritual and cultural practices and beliefs of the amaXhosa. Further access was a driving theme in this study and therefore development and conservation efforts need to heed the value and importance of having access to the marine and coastal environment, not only for sustaining livelihoods but for religious and leisure experiences. Size fractionated biomass was determined to describe the contribution of different cell size assemblages to the overall productivity of Algoa Bay. The analysis showed a general dominance of microplankton cell sizes with the picoplankton not contributing much towards the overall biomass of the period analysed. Cell size of the phytoplankton species provides an indication of the environmental changes, together with contribution towards biomass. Species that bloom also change the productivity of the system, for example a diatom bloom will increase productivity more so than a dinoflagellate bloom. Cell size will influence response of phytoplankton to environmental changes and how phytoplankton adapts physiologically to stressors such as climate change. However in the context of studies linking biodiversity to a socio-ecological framework, size fractionated data is not required and overall productivity and diversity of the system is better suited for this type of study. The direct link between the ecological and social data is the application of the information for management of the ecosystem and as an early warning system. The information learnt from the managers and community also highlights the need for a shared approach to gathering knowledge and learning about the world around us.
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  • Date Issued: 2018

Lipid pathway regulation in high fat diet induced insulin resistance and prevention by Sutherlandia frutescens

  • Authors: Nnolum-Orji, Ngozi Francisca
  • Date: 2018
  • Subjects: Insulin -- Physiological effect , Fatty acids -- Metabolism Lipids in human nutrition
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/33442 , vital:32873
  • Description: Excessive dietary fats are key players in the development of insulin resistance (IR). These fatty acids alter the normal lipid metabolic processes, mostly lipolysis and lipogenesis, through hormonal and transcriptional regulation, and in part, through alterations in the gut microbiota composition and their secretion of short-chain fatty acids (SCFAs). In this regard, extensive knowledge on the development (at different time points) of this deregulation of lipid metabolism by high-fat feeding, and the control thereof, is necessary to identify early biomarkers of metabolic diseases such as IR and T2DM, and provide new pharmacological and behavioural lifestyle intervention strategies. In a previous study at NMMU, male Wister rats developed IR within 56 days of chronic intake of a high-fat diet (HFD), while the group that consumed the same HFD supplemented with aqueous extracts of Sutherlandia frutescens (HFD+SF) were protected from IR (Mackenzie, 2009). The present study investigated the role of the gut microbiota via SCFA secretion, and that of the lipid pathways in the observed IR with high-fat feeding, and in the prevention with S. frutescens supplementation. These were done through study of the over-time (days 28, 56 and 86) regulation of gut-derived SCFAs in the liver and plasma samples, as well as the regulation of lipolytic and lipogenic parameters in the liver and adipose tissue samples of these rats. Quantification of SCFAs was carried out using GC-MS technique, while qRT-PCR was used for estimation of the expression levels of genes coding for lipolytic and lipogenic enzymes and transcriptional/regulatory factors. The results obtained showed no role of gut-derived SCFAs as substrates for lipid metabolism in the study rats. Also, gene expression of the lipolytic enzyme (HSL) did not provide evidence of a causative role of adipose lipolysis in the development of observed IR in HFD rats. However, the importance of adipose tissue insulin sensitivity to the maintenance of normal lipolytic rates was indicated in Sutherlandia treated rats. On the other hand, over-time decrease in the gene expression of lipogenic enzymes (ACC and FAS) in the liver and adipose tissues of HFD rats imply that deregulation of lipogenesis contributed to IR in these rats. Conversely, stimulation of lipogenesis in the S. frutescens treated rats prevented the rats from developing IR. Furthermore, gene expression of the transcription factors (liver PPARalpha for lipolysis; and SREBP-1c and PPARgamma for lipogenesis) correlate these observations. Leptin gene expression supports its effect on lipolysis but not lipogenesis, while gene expressions of SCFA receptors correlate FFAR2, but not FFAR3, to lipogenesis and lipolysis.
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  • Date Issued: 2018

Manufacturing of continuous flow equipment

  • Authors: Strydom, Martin
  • Date: 2018
  • Subjects: Microfluidics , Nanofluids Micro-reactor
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/35818 , vital:33850
  • Description: For the work of this thesis a proof of concept microreactor and pump have been designed. Open source technology was used where possible to reduce the manufacturing cost. The pump is a pseudo HPLC/Syringe pump hybrid which adopts designs from both pumping systems. It works by charging two volumes of liquid into the primary chamber while the secondary chamber discharges. When the charge of the primary chamber is complete half of the liquid is pumped into the secondary chamber and the other half gets discharged. This has the benefit of sharing a common drive to reduce cost. The pump did function; however, the 3D printed parts did not have sufficient rigidity to offset mechanical stress, thus flexing occurred. The micro-reactor that was developed, was unique to commercial units. It was not chemically or thermally bonded but clamped with a gasket sealing the channels. This provides the advantage of unblocking inert material in the reactor. The reactor disk that was clamped was a super alloy, namely, Hastelloy C276. The reactor was tested against two commonly used reactors, namely, Chemtrix3227 and Little Things Factory (MS+VS). A simple synthesis of ethyl acetate has been used as a model reaction for comparing. The test reactor did not perform as well as the commercial counterparts, however probable causes have been identified for potential future work. Both the pump and the reactor worked as a proof of concept system, however further development is required for commercialisation.
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  • Date Issued: 2018

Method development for chemolysis of waste tyres and characterization of the components

  • Authors: Tsipa, Phuti Cedric
  • Date: 2018
  • Subjects: Composite materials , Rubber Chemistry, Organic
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/36694 , vital:34044
  • Description: Chemolysis method for degradation and extraction of waste tyres for production of oil was developed. This method consist of three different solvent systems; firstly, the selective solvent system capable of extracting the process oil used in the production of tyres. This solvent system follows a phase transfer catalysis reaction, which is a reaction with a solvent consisting of two phases. Second system is a Destructive solvent system, which is capable of breaking down the polymer chains within the rubber matrix. It follows phase transfer catalysis reaction. Lastly, the collecting/wash solvent system, which is capable of collecting the remaining extracts in the residual crumb. Three products where obtained from this method: Liquid (oil), Gas and Solid (char), with the oil plus char being the focus of this study. Characterizations were carried out to obtain the quality of the oil recovered. Various analytical techniques were used to achieve the aims and objectives of this study, this involved Fourier Transform Infra-red spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy, High-resolution Thermogravimetric analysis (Hi-resTM TGA), Gas Chromatography coupled to Mass spectroscopy (GC-MS) and Simulated Distillation D86 (SIMDIST D86). Hydrocarbon compounds and market value acids where identified with reference to standards ran on the GC-MS. Market value acids were quantified to obtain the exact amount present in the extracted oil, the amounts for dodecanoic acid, hexadecanoic acid, heptadecanoic acid and octadecanoic acid were 0.73%, 5.1%, 0.49% and 9.98% respectively. Approximately 15% of this market value acid are present in the extracted oil. Internal GC-MS library and Retention Index (RI) methods with the help of NIST library were also used for compounds identification. A total of 53 compounds were successfully identified. SIMDIST D86 analysis showed that the petroleum fractions present in the total extracted oil were Heavy naphtha 0.73%, Kerosene 3.23%, Distillate fuel oil 6.27%, Light vacuum gas oil 57.93% and Heavy vacuum gas oil 31.83%. Hi-resTM TGA was used to characterize the char recovered for thermal properties. Chemolysis char showed relatively similar thermal stability compared to commercial N115 carbon black. The chemolysis method of oil extraction from waste tyres reported in this thesis shows promise in terms of both the routine of execution, quantification of market value constituents of the oil and chemical details of both the tyre derived oil and char.
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  • Date Issued: 2018

Microhabitat and biotic structure of stromatolite formations

  • Authors: Weston, Ross-Lynne Alida
  • Date: 2018
  • Subjects: Stromatolites , Microbial mats Sedimentary structures
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/17493 , vital:28358
  • Description: Stromatolites are among the oldest types of microbial formations. In contrast to their ancient counterparts, many modern marine stromatolites have a coarser internal structure and host a diverse eukaryotic community. Different mesofabric structures are found within stromatolite formations which may provide microhabitat opportunities for organisms. Therefore, the first aim of this study was to investigate how the microalgal (including Bacillariophyta, Chlorophyta and cyanobacteria) community contributes towards the differences observed amongst mesofabric structures in terms of depth profiles and layering at representative stromatolites forming along the Port Elizabeth coastline in South Africa. The second aim was to investigate how the invertebrate community changes between mesofabric types. This was achieved by comparing the proportional abundances of each of the major microalgal classes between the different mesofabric types and depth profiles. Additionally, the invertebrates found within samples collected were identified and counted. These were related to site and environmental characteristics using multivariate modelling. Clear variability in terms of proportional abundance was apparent between microhabitats and with depth. Coarser, more-bioturbated types had a higher bacillariophyte biomass than smoother types. Invertebrate abundance was generally higher in coarser mats. However, one of the finer, well-laminated types had surprisingly more invertebrates than expected, but only in summer. The changes in microalgal and invertebrate community distribution varied seasonally. More microalgae were found in summer and more invertebrates were found in winter. Microalgae distribution was driven by mesofabric features whereas invertebrate distribution was attributed to resource changes. The implications of this study are in terms of the role of microalgae as ecosystem engineers in driving microhabitat differences. The microhabitats provide opportunities for colonisation by invertebrates.
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  • Date Issued: 2018

Molecularly imprinted polymeric materials for adsorptive removal of nitrogen compounds from fuel oils

  • Authors: Abdul-Quadir, Muhammad Sabiu
  • Date: 2018
  • Subjects: Polymerization , Organonitrogen compounds Nitrogen compounds
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/23426 , vital:30542
  • Description: The deleterious effects of refractory polyaromatic hydrocarbons found in fuels such as organonitrogen compounds (quinoline, carbazole and its alkylated derivatives) are such that they emit NOx to the environment when combusted, thereby reducing air quality. These compounds also deactivate the catalyst used during fuel refinement and in catalytic converters of cars. Hydro-denitrogenation (HDN), a process currently being employed in petroleum refineries to eliminate organonitrogen compounds in fuels, is limited in treating these refractory compounds. Hence, this thesis describes the use of two separate complimentary approaches for the removal of organonitrogen compounds in fuel such as oxidative denitrogenation and adsorptive denitrogenation. The catalyzed oxidation of fuel oil model nitrogen containing compound, quinoline to quinoline N-oxide, was conducted under batch and continuous flow microreactor at 70°C by using tert-butylhydroperoxide (t-BuOOH) as oxidant and silica supported V2O5 as catalyst, followed by the selective adsorption of the quinoline N-oxide. An overall conversion of 62% quinoline N-oxide was observed. Quinoline-N-oxide in model fuel was absorbed by employing synthesized molecularly imprinted 2,6-pyridine-polybenzimidazole (2,6-PyPBI) nanofibers, 86% of quinoline-N-oxide was removed to give an adsorption capacity (qe) of 4.8 mg/g. DFT calculations to study the interactions of quinoline-N-oxide vs 2,6-PyPBI indicated that: (i) hydrogen bonding (through amino group of 2,6-PyPBI and oxygen atoms of the quinoline-N-oxide), (ii) pi-pi stacking and (iii) extensive number of van der Waals interactions took place. Several oxygenates from N-compounds were produced, thus, complicating the fuel matrix. Therefore, there is a need to move towards adsorptive denitrogenation. Poly-2-(1H-imidazol-2-yl)-4-phenol (PIMH) imprinted microspheres was prepared by suspension polymerization using 2-(2’-hydroxy-4-ethenylphenyl) imidazole as a functional monomer and ethylene glycol dimethacrylate as a crosslinker in the presence of various organonitrogen compounds (templates) to produce 2-(2’-hydroxy-4-ethenylphenyl) imidazole (PIMH). Imprinted microspheres show selectivity for various target model nitrogen-containing compounds with adsorption capacities of 6.8 ± 0.2 mg/g, 6.3 ± 0.3 mg/g and 5.8 ± 0.3 mg/g for quinoline, pyrimidine and carbazole, respectively. Adsorption selectivity increased in the order of quinoline (αi-r = 136.9) ˃ pyrimidine (αi-r = 126.2) ˃carbazole (αi-r = 86.3), when naphthalene was selected as a reference compound. Though, imprinted microspheres displayed excellent nitrogen compound removal both in model and real fuel, there was a need to improve the adsorbent adsorption capacity for N-compounds in fuel through the fabrication of imprinted nanofibers. Molecularly imprinted poly-2-(1H-imidazol-2-yl)-4-phenol nanofibers was prepared by electrospinning of 2-(2’-hydroxy-4-ethenylphenyl) imidazole (PIMH) in the presence of various organonitrogen compounds. These imprinted nanofibers show selectivity for various target model nitrogen-containing compounds with adsorption capacities of 11.7 ± 0.9 mg/g, 11.9 ± 0.8 mg/g and 11.3 ± 1.1 mg/g for quinoline, pyrimidine and carbazole, respectively. Adsorption selectivity increased in the order of pyrimidine (αi-r = 258.8) ˃ quinoline (αi-r = 235.5) ˃ carbazole (αi-r = 168.2). It further displayed excellent nitrogen removal in real fuel. The use of polybenzimidazole (PBI) nanofibers showed selective adsorption of organonitrogen compounds as imprinted sorbent also displayed high selectivity for their target model nitrogen-containing compounds with adsorption capacities of 11.4 ± 0.4 mg/g, 11.9 ± 0.2 mg/g and 10.9 ± 0.7 mg/g for quinoline, pyrimidine and carbazole respectively. Adsorption selectivity increased in the order of pyrimidine (αi-r = 241.5) ˃ quinoline (αi-r = 237.6) ˃ carbazole (αi-r = 170). Thermodynamic parameters obtained from isothermal titration calorimetry (ITC) revealed that quinoline-PIMH/PBI and pyrimidine-PIMH/PBI interactions are exothermic in nature, while carbazole-PIMH/PBI is endothermic in nature. DFT calculations indicated that π-π interactions/stacking and hydrogen bond interactions took place between N-compounds (carbazole, quinoline and pyrimidine) and adsorbent (PIMH and PBI). A significant reduction in the quantity of nitrogen containing compounds in hydrotreated fuel was observed (peak area reduction) when adsorbents (PIMH and PBI) was employed, however, the complex nature of organonitrogen compounds in fuel complicate the structure/function approach on MIPs for targeting these unwanted compounds.
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  • Date Issued: 2018

Motivation for landscape stewardship as a driver of change-Garden Route, South Africa

  • Authors: Heider, Lisa
  • Date: 2018
  • Subjects: Social ecology , Environmental psychology Conservation (Psychology)
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/30116 , vital:30826
  • Description: Stewardship, as portrayed in much of contemporary literature is considered as a key to the sustainability challenges of the biosphere. In disciplines which regard sustainability in the context of Social Ecological Systems (SES), stewardship is associated with the goal of building resilience through the informal governance structures that dictate how the landscape is utilized. These disciplines lack a better integration of individual roles and responsibilities as they relate to their daily interactions with the environment. Formally initiated stewardship can evoke maladaptation, in other words the attempts to conserve a specific natural assets in one particular locality can shift the problem of degradation or exploitation to another place or point in time. This is because the individual, as an inevitable driver of unsustainability, has not been addressed. What is needed is the knowledge of strategies which resolve human disconnection from nature and the biosphere, through a greater focus on the individual motivational scale. In Chapter 2, which consists of a literature review of recent stewardship discourses, I extract alternative theories which consider individual motivation and subjectivity as the underlying drivers of resilience. These include knowledge about Sense of Place, and theories from Conservation Psychology. Basic Human Value theory is also presented as a possible entry point for societal transformation through individual motivation. These ought to inform conservation interventions with mechanisms which truly grasp unsustainability at its roots. This is a place-based, qualitative study where the results assist in interrogating the question: How does individual motivation for stewardship mediate socialecological trajectories of change? The context of the study and the methods used to generate my research findings are presented in Chapter 3 and 4. The Garden Route provides the place-based context for this research and is situated in the Western Cape Province of South Africa. The region is home to diverse cultures representative of Western and indigenous regions who meet and negotiate what it means to care for the environment. The area is biologically rich and ecologically highly sensitive to current trajectories of development, fragmentation and global change. Mixed methods and a qualitative approach was used to answer three sub-questions: (1) Which theories facilitate greater understanding of transformative stewardship pathways? (2) How can a transformative pathway be recognized? and (3) How can transformative pathways be pursued? One method used in this study is a photo-voice technique, which is coupled with self-directed journaling and in-depth interviews. Other sources of data include communication and engagement, observations iii and focus groups. I apply a content analysis to the transcribed qualitative data to resolve the research questions. Research results are presented in Chapter 5. In this empirical chapter I present three competing meanings of stewardship and visions for change held by individuals in the Garden Route. The three meanings are described as: protect nature from human influence (Nature despite People); work together and communicate (Nature for People/Nature and People); and be the change you want to see in this world (People in Nature). The variable which best describes the differences in visions is Critical Connectivity. Resilience in a SES is critically dependent on three levels of connectivity in stewardship. Firstly, individuals’ consciousness of being interrelated and interdependent within a community of life; Secondly, expressions in the physical landscape which promote the connectivity of ecological systems as well as the connectivity between people and nature. Thirdly, Connectedness with the Biosphere, which means that the boundaries of the planet and the functioning of the life-supporting earth system are considered in behaviours. I use Basic Human Value theory to test whether it can explain how the differences between and commonalities within the three groups arise. The results support the theory, suggesting that Basic Human Values underlie individual motivation for stewardship. However, inconsistencies and shortcomings of Basic Human Value theory became evident. I identified new values and value combinations which were not made explicit in the framework. These emerged due to my in-depth qualitative approach, as opposed to the common quantitative uses of the framework. The qualitative approach allows for values to emerge inductively and it elicits nuances of individual value interpretations that the definitions of Basic Human Values do not depict. In the second part of the empirical chapter, I present evidence of maladaptive and transformative stewardship pathways in the Garden Route. A maladaptive pathway is one in which individuals’ expression of care for the environment undermines Critical Connectivity and transfers vulnerabilities in the SES. A transformative pathway is one in which individuals pro-actively invest into Critical Connectivity and enhance resilience. The differences in these pathways are directly related to the differences in motivation. iv The findings of this research reveal that stewardship is the act of ‘place creation’ which is motivated by unique and nuanced differences in basic values and individual consciousness. Recognizable features of transformative and maladaptive stewardship pathways are discussed in Chapter 6. I present a conceptual model that critically evaluates stewardship. This model firstly assists researchers and practitioners to become alert to early warning signs of maladaptive pathways. Secondly, it informs them of potential leverage points for interventions which can induce sustainability transformations. I then apply this model to discuss transformative and maladaptive pathways against the backdrop of my findings and the literature. The elements which emerged as critical in this assessment are risk perceptions, stewardship meaning, connectivity with nature, connectedness with the biosphere, relationship with place, sustenance and identity. Different configurations of each indicator help explain the different pathways. Lastly, I discuss the role of Basic Human Values in each of the pathways. I compare how the motivational orientation towards self-enhancement and self-transcendence, or towards openness to change and conservation, play roles in SES resilience. This discussion brings to the surface the fact that transformative stewardship rests on a combination of these four value categories. In contrast, the absence of self-transcendent values and the presence of power, security and conformity underlie the motivation for maladaptation. I leave the reader with suggestions for interventions which have become relevant as a result of my study. Policy, media, conservation agencies and science shape meanings of stewardship, portray social norms and hence must motivate Critical Connectivity. Transformations can be achieved by targeting changes in values which must include autonomy, universalism, benevolence and spirituality. I discuss how policy and planning, communication, marketing and education can lever transformation through mechanisms identified in my research. Chapter 7 concludes this research with a reflective summary of the academic and practical contributions my study has made for stewardship discourses and for the management of SES resilience in local landscapes. I provide recommendations for further research, as they apply to socio-political change in Post-Apartheid South Africa. I end the concluding chapter by encapsulating my research finding in future scenarios for the Garden Route in the face of change, which namely relate to abrupt and uncertain environmental change, immigration, population growth and implications for spatial planning, and the Garden Route Biosphere Reserve. v In Chapter 8, I provide a reflection of this research. This entails foremost a reflection of how I have accounted for four quality criteria in social research, which are namely dependability, credibility, conformability and transferability. I end the chapter with the limitations and outline of scope of my study..
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  • Date Issued: 2018
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