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Evaluating the cyber security skills gap relating to penetration testing

  • Authors: Beukes, Dirk Johannes
  • Date: 2021
  • Subjects: Computer networks -- Security measures , Computer networks -- Monitoring , Computer networks -- Management , Data protection , Information technology -- Security measures , Professionals -- Supply and demand , Electronic data personnel -- Supply and demand
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/171120 , vital:42021
  • Description: Information Technology (IT) is growing rapidly and has become an integral part of daily life. It provides a boundless list of services and opportunities, generating boundless sources of information, which could be abused or exploited. Due to this growth, there are thousands of new users added to the grid using computer systems in a static and mobile environment; this fact alone creates endless volumes of data to be exploited and hardware devices to be abused by the wrong people. The growth in the IT environment adds challenges that may affect users in their personal, professional, and business lives. There are constant threats on corporate and private computer networks and computer systems. In the corporate environment companies try to eliminate the threat by testing networks making use of penetration tests and by implementing cyber awareness programs to make employees more aware of the cyber threat. Penetration tests and vulnerability assessments are undervalued; are seen as a formality and are not used to increase system security. If used regularly the computer system will be more secure and attacks minimized. With the growth in technology, industries all over the globe become fully dependent on information systems in doing their day-to-day business. As technology evolves and new technology becomes available, the bigger the risk becomes to protect against the dangers which come with this new technology. For industry to protect itself against this growth in technology, personnel with a certain skill set is needed. This is where cyber security plays a very important role in the protection of information systems to ensure the confidentiality, integrity and availability of the information system itself and the data on the system. Due to this drive to secure information systems, the need for cyber security by professionals is on the rise as well. It is estimated that there is a shortage of one million cyber security professionals globally. What is the reason for this skills shortage? Will it be possible to close this skills shortage gap? This study is about identifying the skills gap and identifying possible ways to close this skills gap. In this study, research was conducted on the cyber security international standards, cyber security training at universities and international certification focusing specifically on penetration testing, the evaluation of the need of industry while recruiting new penetration testers, finishing with suggestions on how to fill possible gaps in the skills market with a conclusion.
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  • Date Issued: 2021

An investigation into the synergistic association between the major Clostridium cellulovorans cellulosomal endoglucanase and two hemicellulases on plant cell wall degradation

  • Authors: Beukes, Natasha
  • Date: 2008
  • Subjects: Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3968 , http://hdl.handle.net/10962/d1004027 , Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
  • Description: The cellulosome is a multimeric enzyme complex that has the ability to metabolise a wide variety of carbonaceous compounds. Cellulosomal composition may vary according to the microbe’s nutritional requirement and allows for the anaerobic degradation of complex substrates. The complex substrates of interest in this research study were sugarcane bagasse and pineapple fibre waste, as they represent two important lignocellulosic, South African agricultural crops. The effective degradation of complex plant biomass wastes may present a valuable source of renewable compounds for the production of a variety of biofuels, for example bioethanol, and a variety of biocomposites of industrial importance. The identification of renewable energy sources for the production of biofuels is becoming increasingly important, as a result of the rapid depletion of the fossil fuels that are traditionally used as energy sources. An effective means of completely degrading lignocellulose biomass still remains elusive due to the complex heterogeneity of the substrate structure, and the fact that the effective degradation of the substrate requires a consortium of enzymes. The cellulosome not only provides a variety of enzymes with varying specificities, but also promote a close proximity between the catalytic components (enzymes). The close proximity between the enzymes promotes the synergistic degradation of complex plant biomass for the production of valuable energy products. Previous synergy studies have focused predominantly on the synergistic associations between cellulases; however, the synergy between hemicellulases has occasionally been documented. This research project established the synergistic associations between two Clostridium cellulovorans hemicellulases that may be incorporated into the cellulosome and a cellulosomal endoglucanase that is conserved in all cellulosomes. This research study indicated that there was indeed a synergistic degradation of the complex plant biomass (sugarcane bagasse and pineapple fibre). The degrees of synergy and the ratio of the enzymes varied between the two complex substrates. The initial degradation of the bagasse required the presence of all the enzymes and proceeded at an enhanced rate under sulphidogenic conditions; however, there was a low production of fermentable sugars. The low quantity of fermentable sugars produced by the degradation of the bagasse may be related to the chemical composition of the substrate. The sugarcane contains a high percentage of lignin forming a protective layer around the holocellulose, thus the glycosidic bonds are shielded extensively from enzymatic attack. In comparison, the initial degradation of the pineapple fibre required the action of hemicellulases, and proceeded at an enhanced rate under sulphidogenic conditions. The initial degradation of the pineapple fibre produced a substantially larger quantity of fermentable sugars in comparison to the bagasse. The higher production of fermentable sugars from the degradation of the pineapple fibre may be explained by the fact that this substrate may have a lower percentage of lignin than the bagasse, thus allowing a larger percentage of the glycosidic bonds to be exposed to enzymatic attack. The data obtained also indicated that the glycosidic bonds from the hemicellulosic components of the pineapple fibre shielded the glycosidic bonds of the cellulose component. The identification of the chemical components of the different substrates may allow for the initial development of an ideal enzyme complex (designer cellulosome) with enzymes in an ideal ratio with optimal synergy that will effectively degrade the complex plant biomass substrate.
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  • Date Issued: 2008

Ecological principles for honeybush (Cyclopia spp.) conservation and cultivation

  • Authors: Beyers, Andrea
  • Date: 2016
  • Subjects: Fynbos -- South Africa , Rooibos tea industry -- South Africa , Herbal teas -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/5723 , vital:20975
  • Description: Market demand for the fynbos-derived honeybush (Cyclopia spp.) tea is on the rise, and there is an urgent need for better conservation of wild Cyclopia populations and for a shift to sustainable cultivation. Rooibos is another popular fynbos product that underwent exponential market growth over the last two decades but this resulted in large-scale conversion of pristine mountain fynbos to intensively-used crop lands. Adopting a conservation agriculture approach in expanding indigenous products will help in conserving biodiversity and ecosystem processes in this global biodiversity hotspot. Conservation agriculture of indigenous fynbos products grown in the Cape Floristic Region (CFR) should follow five main principles in order to maximise biodiversity conservation alongside agriculture. These principles are: 1) maintain high diversity at all levels, 2) conserve soil structure and processes, 3) conserve and restore natural ecosystem processes, 4) promote ecosystem stability and self-perpetuation, and 5) maintain natural areas as sources of ecosystem components. Given the negative ecological consequences of the industrialisation of the rooibos industry, it would be in the interest of biodiversity conservation, and even of agriculture, to apply these principles to honeybush cultivation. In order to prevent further fynbos habitat loss, cultivation of honeybush could be catalysed on old fields rather than in ploughed or cleared fynbos. Here I compare germination, growth and survival of two species (Cyclopia intermedia E.Mey. and C. subternata Vogel) between different land use types (ploughed lands, old fields and intact fynbos) and treatments (cleared and uncleared) in the Langkloof, Eastern Cape, over one year. Plots of each land use type were subject to each of these two treatments, although the ploughed plot constituted only a cleared treatment. Growth was highest on ploughed land, while survival and growth were lowest in uncleared fynbos. Cleared fynbos had the lowest germination success in both species, with the other sites and treatments coming out roughly the same. These results show that although ploughed lands give highest yields, growth and survival on old fields without ploughing is comparable with that on ploughed lands and is therefore a feasible alternative. Understanding the recruitment dynamics of honeybush is imperative for adequate conservation of wild populations. Furthermore, understanding this ecological aspect of the genus will help in developing the honeybush industry as a sustainable, agroecological market that uses semi-natural populations for production. Although Cyclopia species are early-successional species that germinate after fire, recruitment of Cyclopia pubescens Eckl. & Zeyh. continues throughout the inter-fire period. Cyclopia pubescens populations near Port Elizabeth were described according to their age structure and plant densities to discern possible density-dependent recruitment effects. Results showed that dense stands for the most part do not support high post-fire recruitment. This gives insight into suitable planting densities for new or restore populations and into management guidelines for remnant populations of threatened species. This thesis highlights important issues facing the honeybush industry. Mainstreaming biodiversity conservation into honeybush production is achievable, given that the industry is still relatively young, but this will require further research and strong market leadership.
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  • Date Issued: 2016

An experimental study of the effect of Acacia mearnsii (black wattle trees) on streamflow in the Sand River, Eastern Cape

  • Authors: Beyers, Gregory John
  • Date: 1999
  • Subjects: Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4832 , http://hdl.handle.net/10962/d1005507 , Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
  • Description: This thesis explores the effect of Acacia mearnsii on streamflow in the Eastern Cape. There is a need for data on the localised effects of removing alien trees from the riparian zones within the Fynbos Biome. Fynbos catchments throughout the Western and Eastern Cape yield large quantities of good quality water which is an essential resource in the region. To convince local land owners to manage their riparian zones, small scale experimental results will prove invaluable to assure them of the immediate advantages for themselves and for downstream water users. Three permanent weirs were built 500 m apart to monitor the effect of removing A. mearnsii on streamflow in the Sand River, Eastern Cape. Consecutive weirs allowed for the comparison of streamflow between a cleared and uncleared section of the river without significant differences in riparian conditions, channel morphology and vegetation densities. A site survey confirmed comparable densities of A. mearnsii in both sections. A sample of trees was weighed and a relationship was found between diameter at breast height and above ground wet biomass. Between the first two weirs, 2.5 ha of riparian zone was cleared amounting to approximately 160tlha. Streamflow was monitored from the 10th of January 1996 to the 9th of September 1996. The average streamflow reduction for the duration of the experiment was 15.1 m³/ha/day or 551 mm per annum. Initially, after a period of above average rainfall, streamflow was augmented by discharge from the riparian zone but as conditions dried out, there was a net uptake of water with the highest average uptake of 23. 7m³/ha/day in June. A comparison between weather conditions and streamflow reduction indicated there is a complex relationship, with evidence of A. mearnsii exhibiting control of water loss during dry conditions. Acacia mearnsii trees in the riparian zone have been shown to cause significant streamflow reduction. Permanent weirs were found to be appropriate for this type of study. There is a need for further research on the effect of alien trees in riparian zones around South Africa as there is potential for significant increases in streamflow.
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  • Date Issued: 1999

A stunting profile of children under the age of five visiting Bhisho hospital clinic, part of the umbrella project: a profile of stunting in children under the age of five in food insecure villages in Mqanduli, Ngqushwa and Bhisho hospital, Eastern Cape, South Africa

  • Authors: Beyleveld, Janine
  • Date: 2020
  • Subjects: Children -- growth
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/50201 , vital:42066
  • Description: Introduction and Background: Stunting is the most prevalent form of childhood malnutrition where about 149 million children under the age of five can be classified as stunted globally. South Africa has one of the highest stunting rates in the world at 27%, causing devastating effects on economic productivity as well as on an individual’s nutritional status. The presence of stunted growth in children is a strong indicator of chronic undernutrition and highlights injustices experienced within communities. Aims and Objectives: The aim of this study is to develop a stunning profile of children under the age of five, visiting BhishoHospital’s gateway clinic in the Eastern Cape, South Africa. The objectives were to determine the prevalence of stunting of the children visiting Bhisho Hospital’s clinic and to identify the drivers of stunting in the area. Methodology: A quantitative study with a descriptive, cross-sectional design was used. The study population included all children under the age of five visiting Bhisho Hospital’s clinic. Data was collected by means of an interview-administered questionnaire. Results: The prevalence of stunting in the area was 47.5%. A significant association was found between the participants' main form of sanitation and stunting category in the group of infants younger than six months (p = 0.007) and the group older than six months(p = 0.040). Discussion: The prevalence of stunting in the area was far higher than the national average of 27%, although the majority of the sample had a normal weight. The use of non-flush toilets was found to be a risk factor for childhood stunting. Recommendation: Financial and political investment in child health needs to be placed as a top priority in South Africa to reduce stunting rates.
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  • Date Issued: 2020

Sandy beach food webs and trophic linkages with estuaries: a stable light isotope approach

  • Authors: Bezuidenhout, Karien
  • Date: 2010
  • Subjects: Stable isotopes in ecological research -- South Africa -- Eastern Cape , Food chains (Ecology) -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10694 , http://hdl.handle.net/10948/1269 , Stable isotopes in ecological research -- South Africa -- Eastern Cape , Food chains (Ecology) -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape
  • Description: Two pocket sandy beaches, Eastern Cape, South Africa, were investigated, to determine whether these beaches were subsidised by an adjacent mangrove estuary, by using stable light isotope (δ 13C and δ 15N) analyses. The trophodynamics and macrofaunal food webs of these two beaches, situated between the Mgazi and Mgazana estuaries (in a warm-temperate/subtropical transition zone,), were described. Two to 2.5 trophic levels were identified for the macrobenthic community, with suspension feeders and omnivorous scavengers as the primary consumers, and carnivores as the secondary consumers. Mangrove material and terrigenous inputs were not driving the sandy beach food webs. Instead, marine allochthonous inputs (carrion, macroalgae), possibly phytoplankton, sediment organic matter, and resident macroinfauna were the dominant food sources. Cattle dung could have been the only important terrigenous food source utilised by the beach benthos. The macroinfauna displayed generalist/omnivorous feeding strategies, but within the limits of predominantly marine food sources. There was evidence that carnivores actively preyed on resident beach fauna. Omnivory and intraguild feeding might also be important biological processes in these communities. Seasonal and spatial variability in stable isotope composition of the fauna was observed, but few patterns were evident. There was a general trend of more enriched δ 15N and δ 13C composition of animal tissues in summer as opposed to winter. This was accompanied by a general decrease in C:N ratios in summer. It was hypothesised that these isotopic and biochemical changes were in response to increased food availability during summer. Although mangrove material appeared not to play an important role in the nutrition of these sandy beach communities, it was suggested that a high retention time of particles in the bay could enhance bacterial decay of particulate mangrove material, which could then act as fine, bacterial-enriched particulate food to the macrobenthos. This remains to be tested.
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  • Date Issued: 2010

On the characterisation of photovoltaic device parameters using light beam induced current measurements

  • Authors: Bezuidenhout, Lucian John-Ross
  • Date: 2015
  • Subjects: Solar cells--Materials , Semiconductors
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10551 , http://hdl.handle.net/10948/d1020282
  • Description: Light Beam Induced Current (LBIC) measurement is a non-destructive technique used to perform localized characterization of solar cells using a light beam as a probe. The technique allows the determination of local photo response of a cell, the electrical parameters and defects that occur in the individual solar cell. The semiconductor materials used to create solar cells are not always defect free and these defects reduce the electrical performance of the device. It is therefore important to use a system that will allow the characterization and extract the solar cell parameters as can be done using the LBIC system. By analysing these parameters and cell defects, further studies can be done to enhance the cell’s lifetime and hence its efficiency. Light beam induced current (LBIC) is a technique that focuses light onto a solar cell device and thus creating a photo-generated current that can be measured in the external circuit for analyses. By scanning this beam probe across a solar cell while measuring the current-voltage characteristics, a map of various parameters can be obtained. This thesis presents the design of the LBIC system, the software interfacing of the data acquisition system and local photo-response within different solar cell technologies. In addition, this thesis represent two curve fitting algorithms namely: the Gradient Descent Optimisation and the Differential Evolution used for the extraction of solar cell device parameters. The algorithms are based on the one-diode solar cell model and make use of the light generated current-voltage (I-V) data obtained from the LBIC system. Different solar cell technologies namely; single crystalline (c-Si) and multicrystalline silicon (mc-Si) was used for analysis. LBIC maps and I-V characteristics of both technologies was obtained. The LBIC maps shows performance degrading defects present in the bulk and the surface of the solar cells as a function of spatial distribution. These localised defects acts as trapping mechanism for the charge carriers and therefore limits recombination within the solar cell and thus decreasing the performance of the solar cell device. The resulting I-V characteristics obtained from the LBIC system were used to determine the performance parameters using the two algorithms. The resultant effect of these parameters on the performance of the solar cells was observed. The overall results showed that LBIC is a useful tool for identifying and characterising defects in solar cells.
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  • Date Issued: 2015

The effects of age on the worker capacity and mechanisation on the task demands in a South African manufacturing industry

  • Authors: Bezuidenhout, Samantha Catherine
  • Date: 2014
  • Subjects: Age and employment -- South Africa , Labor -- Social aspects -- South Africa , Brickmaking -- South Africa -- Automation , Brickmaking -- Social aspects -- South Africa , Brick trade -- South Africa , Aging -- Social aspects -- South Africa , Aging -- Research
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5151 , http://hdl.handle.net/10962/d1013167
  • Description: The focus of the study was two-fold, firstly to determine the effect of age on the capacity of manual materials handling workers and secondly to determine the effect of increasing task mechanisation on the workers’ responses to task demands. The first component of this study, namely Part I, 101 male and 12 female ‘unskilled’ manual workers – of various ages – from a brick manufacturing industry were assessed. Anthropometric, health and strength factors were measured to improve the understanding of the South African manual worker capacity and more specifically, the effect of age on this capacity. Data collection was done between 7.30am and 9.30am in a laboratory-type setting on-site. Anthropometric characteristics (including body mass index, waist to hip ratio, waist circumference and body fat percentage) provided information on the state of obesity and the impact of age in the South African context. Linked to this, the health factors (including blood pressure, resting heart rate and a self-reported questionnaire) provide an extra snapshot of the disease profile in South Africa, and could potentially influence other capacity factors. Isometric strength capacities (of eight different areas, namely: back, leg, bicep, shoulder, pinch, pinch and pull) demonstrated whether South African manual workers show the same decline in strength with aging as seen in industrially advanced countries. The second component of the study, Part II, was performed in situ and measured the workers’ responses to task demands of three brick palletising tasks, one manual (n=21) and two with increasing mechanisation (n=12 each). Spinal kinematics, joint forces and working heart rate were assessed on normal work days during a 30-lift duration and body discomfort measures were taken at the start, middle and end of the work-shift. Spinal kinematics were measured dynamically using a lumbar motion monitor, whereas the spinal forces were estimated using the three dimensional static strength prediction program. The worker capacity results showed that waist to hip ratio, waist circumference and body fat percentage increased significantly with aging, whereas body mass index was not affected by age. All body morphology values were within ‘normal’ ranges. Although diastolic blood pressure increased significantly with age, systolic was not affected significantly by age. Both groups, however, showed an increasing prevalence of hypertension with aging. There were no significant changes in resting heart rate with aging, with a range of 66 bt.min⁻¹ to 74.86 bt.min⁻¹, therefore within normal ranges. Of the strength factors, age only affected shoulder and push strength significantly: Showing a decrease in shoulder strength from 49.89 kgF to 39.91 kgF in the men aged 20-29 to the 50-59 respectively and an increase in push strength from men aged 30-39 and 40-49 to those aged 50-59. Part II results revealed highly frequent lift rates and large degrees of sagittal flexion and lateral bending in all three tasks. These postures adopted for long durations are likely to lead to the development of musculoskeletal disorders. Heart rates of workers from the three tasks were significantly different and heart rates for two tasks were above the recommended 110 bt.min⁻¹. Similarly the body discomfort ratings of the three tasks differed, although a common trend was seen in that lower back pain was the most commonly reported area of discomfort in all tasks. South African manual materials handling males did not show the same responses to aging as men from industrially advanced countries, calling for further research into these differences. Due to the high risks of the three tasks assessed, future research and interventions are required to reduce the risk of injury in the assessed tasks.
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  • Date Issued: 2014

Delineation of buried stream channels using geophysical techniques

  • Authors: Biedler, Murray W
  • Date: 1994
  • Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
  • Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
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  • Date Issued: 1994

A study of four-dimensional oscillator groups and the associated left-invariant control affine systems

  • Authors: Biggs, Rory
  • Date: 2012
  • Subjects: Uncatalogued
  • Language: English
  • Type: thesis , text , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/164941 , vital:41186
  • Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Mathematics, 2012
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  • Date Issued: 2012

Eco-ethology of shell-dwelling cichlids in Lake Tanganyika

  • Authors: Bills, Ian Roger
  • Date: 1997
  • Subjects: Cichlids -- Africa, East , Cichlids -- Tanganyika, Lake , Fishes -- Behavior
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5265 , http://hdl.handle.net/10962/d1005109 , Cichlids -- Africa, East , Cichlids -- Tanganyika, Lake , Fishes -- Behavior
  • Description: Observations of habitats are reported. A series of underwater experiments were conducted in natural habitats to answer questions concerning a) why Lamprologus ocellatus and Lamprologus ornatipinnis bury gastropod shells refuges into the substrate, and b) to examine interspecies differences in shell-using behaviours. Some behaviour patterns were analysed using phylogenetic methods. Lamprologus ocellatus and L. ornatipinnis responded to new shells in a variety of ways, shells were moved, buried (and used) or hidden (buried and not used). How shells are utilised seems to be dependant on a complex of factors such as the size and quality of new the shell and the number already in the territory. Shell use may also be affected by neighbour species, sex, size and predation levels. There are interspecific differences in the size of shells used and the methods of shell use. The latter results in species-characteristic shell orientations, vertical burial in L. ocellatus and horizontal burial in L. ornatipinnis. Shell orientation does affect other species/use of shells. Shell movement and vertical orientation appear to be apomorphic while shell hiding and burial are pleisiomorphic within the genus Lamprologus. Numerous cues are involved in stimulating shell burial. Most of these cues are actively sought by the fish by external and internal inspections. Shell burial therefore appears to be a method of reducing the information gathering ability of potential shell-dwelling competitors. Shell burial can therefore be regarded as an investment process which enhances the residents ability to defend its territory. Males can also control the distribution of open shells within teritories and thus control mate access to shells. This behaviour could be a significant factor in the evolution of marked sexual dichromatism exhibited within the genus.
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  • Date Issued: 1997

An evaluation of recirculating artificial stream designs for acute toxicity testing using two South African Ephemeroptera species exposed to sodium sulphate

  • Authors: Binder, Markus
  • Date: 2000
  • Subjects: Water -- Pollution -- Toxicology , Toxicology -- Research , Aquatic organisms -- Effect of water pollution on , Sodium sulfate , Mayflies
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5690 , http://hdl.handle.net/10962/d1005376 , Water -- Pollution -- Toxicology , Toxicology -- Research , Aquatic organisms -- Effect of water pollution on , Sodium sulfate , Mayflies
  • Description: Three artificial stream designs, termed Large Artificial Stream Units (LASUs), Raceways, and Channels, at two major scales (1700 L, 12.5 L and 20 L recirculated volume) were developed at the Institute for Water Research, Rhodes University, Grahamstown, in order to explore the possibilities of using indigenous rheophilic macroinvertebrates in routine toxicity tests. This study compared these systems, using 96h-EC50 values from sodium sulphate toxicity tests as the experimental response. Two local Ephemeroptera (Leptophlebiidae: Adenophlebia auriculata Eaton, and Baetidae: Afroptilum sudafricanum Lestage) were evaluated for their suitability in routine toxicity tests; and the possible effects of elevated salinity levels in South African rivers on the test species were assessed. Two sets of experiments with each mayfly species were conducted, following an unreplicated regression design. Dechlorinated tap water was used as the water source. Experiments in the Channels were repeated to determine experimental variability. Results were compared statistically by testing for overlap of 95% confidence limits (95%Cls) of EC50 values. The differences between A. auriculata EC50 values in the different systems were statistically significant (no overlap of 95%CLs), but they were not more variable than has been considered normal for biological systems (Coefficient of variation 20.1 %; ratio of greatest EC50 / smallest EC50 1.63). The differences were not related to the scale or the average current velocity characteristic of each stream design (average current velocity LASUs - Raceways - Channels 0.090 - 0.083 - 0.038 m/s). The Channels proved to be most efficient with regard to practical performance as they are portable and easily transportable, user-friendly, reliable, splash-free, cost effective to construct, and can easily be adapted to specific requirements. These systems are therefore recommended for regular use. The suitability of the two mayfly species for routine toxicity testing was evaluated. A. auriculata EC50 values showed a significant negative correlation with the corresponding average body-size (range 1476 - 1610 μm, mean 1555 μm). The different average body-sizes probably reflected the abundance of a certain size range present in the Palmiet River at the time of collection. Both species reacted similarly to Na₂S0₄ (similar slopes of the toxicity curves), identifying this salt as a slow acting toxicant. A. sudafricanum populations were more sensitive to Na₂S0₄ (EC50 3.404 g/L) than A. auriculata (EC50 8.090 g/L), probably because of its smaller body-size (mean 709 μm) and a lack of extremely tolerant individuals. In comparison to other freshwater macro invertebrates, including the standard toxicity test organism Daphnia spp., both mayfly species seemed to be moderately tolerant of Na₂S0₄; therefore there was no particular advantage to using these indigenous taxa rather than Daphnia spp. An assessment of the effects of elevated salinity/TDS levels on the test taxa yielded preliminary insights. A NaCI-EC50 for A. sudafricanum could be extrapolated and suggested a higher sensitivity to Na₂S0₄ than to NaCl. When Na₂S0₄ EC50 values of both species were compared to selected TDS levels of South African rivers, 4. auriculata would mostly not be affected, but A. sudafricanum might occasionally suffer from sub-lethal effects, depending on the sulphate proportion of the TDS. The South African guideline for TDS seemed to protect both species sufficiently.
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  • Date Issued: 2000

The influence of briefing on Eastern Cape government project outcomes

  • Authors: Binqela, Lukhanyo
  • Date: 2019
  • Subjects: Government projects -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/44562 , vital:38128
  • Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
  • Full Text:
  • Date Issued: 2019

The influence of briefing on Eastern Cape government project outcomes

  • Authors: Binqela, Lukhanyo
  • Date: 2019
  • Subjects: Project management -- South Africa -- Eastern Cape , Construction industry -- South Africa -- Eastern Cape Construction industry -- Management
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/44895 , vital:38186
  • Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
  • Full Text:
  • Date Issued: 2019

Human-river relationships in the Kat River catchment and the implications for integrated water resource management (IWRM) : an exploraratory study

  • Authors: Birkholz, Sharon Alice
  • Date: 2009
  • Subjects: Aquatic ecology -- South Africa -- Kat River , Rivers -- South Africa -- Kat River -- Sociological aspects , Rivers -- South Africa -- Kat River , Water supply -- South Africa -- Kat River -- Management , Human ecology -- South Africa -- Kat River , Stream ecology -- South Africa -- Kat River
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: vital:4838 , http://hdl.handle.net/10962/d1005514
  • Description: Through out this study ‘relational scenarios’ were seen as the possible outcomes of the expression of human-river relationships in a catchment. Working within Inglis’s (2008, pg. 10) comment that ‘the Human World Relationship is expressed through a person’s views and behaviour towards the natural world, which can be either constructive or destructive’, two relational scenarios were selected to represent these two predicted outcomes of human-environment (or in the case of this thesis human-river) relationships: IWRM, seen as constructive and mutually beneficial to both the social and ecological system, and the Tragedy of the Commons, seen as destructive and parasitic in nature. In respect to this assertion, a conceptual framework or model was developed and used to guide the inductive process of this research. Through a social survey (administered via semi-structured interviews) of stakeholders (water-users) in the Kat River Catchment, Eastern Cape, South Africa, social attitudes towards the Kat River were explored. These attitudes were considered as variables that relate to the expression of ‘Human World Relationships’ namely ‘values and behaviour’ (Inglis, 2008, pg. 10). The findings of this thesis confirm that attitudes are influential components of human-river relationships in the Kat River Catchment. It was observed from the findings that the attitudes individuals have towards the Kat River have the potential to influence the ways people interact with the River and its associated resources, and are in turn influenced by the condition of the River and connections people have or make with the River within their daily lives. Such relationships in turn affect the management of the River and its water resources and influence how individuals approach water-related issues and undertake the associated activities. Given this understanding it was then proposed that attitudes could provide information that enables the prediction of likely ‘relational scenarios’ (IWRM or the Tragedy of the Commons) in a catchment. The findings appear to support this proposal, and three main attitude groups (utilitarian, associative and dissociative) were identified and used to further the discussion into how this knowledge could be used in predicting possible relational scenarios based on human-river relationships. Further exploration of the identified attitude groups suggested that these variables are significantly influenced by environmental ethics and place attachment (present in the community) and a series of guiding frameworks were developed to facilitate the exploration of the attitude groups relative to these concepts. The frameworks were generated from the hypothesis that knowledge of attitude groups in a catchment, in connection with the relative degrees to which moral values and worldviews are expressed, could provide insight into the readiness of a catchment system for the implementation of IWRM and/or the facilitative steps needed to shift the influence of unfavourable attitude groups (i.e. dissociative attitudes). Such steps would most likely involve extensive educational, awareness and capacity building programs. Finally, given the above theoretical frameworks, inductively developed from the findings of the social survey and related literature, the conceptual model was reevaluated and extended to include the thesis findings and hypotheses. It is suggested that in a catchment where there is a balance between the expression of utilitarian and associative attitude groups, then there is a high probability of finding present evidence of mutually beneficial human-river relationships already in play, as well as ‘fertile soil’ for the promotion of IWRM and philosophies and skills that generate such relationships. Alternatively in an area with a strong expression of dissociative attitudes, it is more likely to find evidence of destructive, more parasitic-like relationships being expressed, and a lack of commitment and interest in being involved in changing the status quo. It is likely that where both associative and dissociative attitudes are present there will be an overlap of elements of both scenarios – a situation that is probable in most catchments – depending on the strength of expression of either attitude group the balance will shift (be shifting) between the two relational scenarios.
  • Full Text:
  • Date Issued: 2009

Age, growth, reproduction and sexual dimorphism of the striped dolphin, Stenella coeruleoalba, off the south-east coast of southern Africa

  • Authors: Bishop, Amy Ruth
  • Date: 2014
  • Subjects: Striped dolphin -- Conservation -- Africa, Southern , Striped dolphin -- Development -- Africa, Southern , Striped dolphin -- Africa, Southern -- Reproduction , Striped dolphin -- Age determination -- Africa, Southern , Dolphins -- Conservation -- Africa, Southern , Dolphins -- Development -- Africa, Southern , Dolphins -- Africa, Southern -- Reproduction , Dolphins -- Age determination -- Africa, Southern , Dimorphism (Animals)
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5848 , http://hdl.handle.net/10962/d1011600 , Striped dolphin -- Conservation -- Africa, Southern , Striped dolphin -- Development -- Africa, Southern , Striped dolphin -- Africa, Southern -- Reproduction , Striped dolphin -- Age determination -- Africa, Southern , Dolphins -- Conservation -- Africa, Southern , Dolphins -- Development -- Africa, Southern , Dolphins -- Africa, Southern -- Reproduction , Dolphins -- Age determination -- Africa, Southern , Dimorphism (Animals)
  • Description: The striped dolphin, Stenella coeruleoalba, is an oceanic dolphin found worldwide in tropical to warm temperate waters. Globally populations are threatened through direct fishing, bycatch and pollution. Little is known about the life history of this species in South African waters and it is currently listed as ‘Data Deficient’ by the International Union for Conservation of Nature (IUCN). Critical to the conservation and management of this species is an understanding of basic life history parameters. For the present study, metadata and tissues from 101 stranded S. coeruleoalba along the south-east coast of southern Africa between 1969 and 2012 were analyzed to examine age and growth, male and female reproduction and sexual dimorphism. Age and growth were determined by counting the number of growth layer groups (GLG’s) present in their teeth. A von Bertalanffy growth curve gave the best fit to the data and indicated that physical maturity was reached around 21 years in males and 18 years in females. Additionally, asymptotic lengths were reached at 231cm and 224cm in males and females, respectively. The maximum ages obtained were 21 years for males and 20 years for females. Length at birth was estimated to be between 116cm and 119cm for males and between 112cm and 114cm for females. The reproductive status of the adult dolphins was assessed by histological and macroscopic analyses of gonadal tissue. Sexual maturity was attained before physical maturity in both sexes. The males reached sexual maturity between 8 and 12 years of age and between 209 and 224cm in total body length. The maximum combined testis weight comprised about 0.24% of the total body weight and sexual maturity was reached between a combined testis weight of 16 and 41g, a mean testis length of 8 and 10cm, and a mean seminiferous tubule diameter of 44 and 70μm. Females attained sexual maturity between 7 and 8 years of age and between 213 and 216 cm in total body length. The ovulation rate was 0.32 per year and the majority of ovulations occurred in the left ovary, with ovulations occurring in the right ovary only in individuals older than 10 years of age. The annual pregnancy rate was calculated to be 26%. Reproductive seasonality could not be established due to the small sample size and the absence of samples throughout the year. However, both conceptions and births appear to occur in both August and December/January. Additionally, testis weight and seminiferous tubule diameters appear to fluctuate throughout the year, which could suggest reproductive seasonality in this species. Sexual size dimorphism in mature adults was evident for a number of external measurements, however, sexual shape dimorphism was not present in this species. Mature males had significantly longer and wider pectoral fins, dorsal fins and flukes than females (p<0.05 in all cases). It was suggested that the larger appendages are required for male on male combat during intraspecific competition for females. Additionally, larger appendages aid in thermoregulation, propulsion and maneuverability. Females had a significantly greater distance between the tip upper jaw and the genital aperture and anus, which was expected due to differences in anatomy between male and female genital openings. Overall, S. coeruleoalba did not exhibit distinct sexual dimorphism and together with the relatively small testes in relation to the total body weight (0.24%) it was proposed that this species demonstrates a less extreme form of polygyny. Additionaly, the results of this study are important to the understanding of the basic biology of the species.
  • Full Text:
  • Date Issued: 2014

The feeding ecology, habitat selection and hunting behaviour of re-introduced cheetah on Kwandwe Private Game Reserve, Eastern Cape Province

  • Authors: Bissett, Charlene
  • Date: 2005
  • Subjects: Kwandwe Game Reserve (South Africa) , Cheetah -- Behavior -- South Africa -- Eastern Cape , Cheetah -- Nutrition -- South Africa -- Eastern Cape , Cheetah -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5698 , http://hdl.handle.net/10962/d1005384 , Kwandwe Game Reserve (South Africa) , Cheetah -- Behavior -- South Africa -- Eastern Cape , Cheetah -- Nutrition -- South Africa -- Eastern Cape , Cheetah -- South Africa -- Eastern Cape
  • Description: The re-introduction of cheetah onto small reserves in the Eastern Cape Province has created the opportunity to study this species in an environment (Valley Bushveld) in which it has not previously been studied and which is quite different from the less wooded habitats in which previous studies have occurred. Thus the aim of this study is to add to the growing number of studies of cheetah in more wooded habitats and to contribute a better understanding of the level of specialization or adaptability in space use, habitat selection, diet and hunting behaviour that the cheetah possesses. The research was conducted on Kwandwe Private Game Reserve from February 2003 to August 2004. Direct observations, scat analysis and continuous observations were used to avoid bias towards large sized prey found when only using direct observations to study diet. The cheetah killed 15 species and four of the five most important prey species (kudu, springbok, grey duiker and bushbuck) were hunted according to their abundance on the reserve, while impala, the fifth most important prey species, was avoided (i.e. preference index less than one) by the cheetah. The cheetah’s main prey was medium sized ungulates, although the three male coalition killed larger prey than females and females with cubs. The daily food intake per cheetah per day was calculated to range from 5.3kg/cheetah/day for the coalition to 8kg/cheetah/day for a solitary female. Home range areas ranged from 11.1 km² for female cheetah with cubs in a den to 65.6 km² for single female cheetah and core areas ranged from 6 km² for the three male coalition to 26.5 km² for independent cubs. Habitat selection by cheetah on Kwandwe varied between the social groups depending on their susceptibility to predation by lions, their need for cover and need for water, and was similar to what has been previously reported. The home range of the coalition incorporated the most open vegetation type (karroid shrubland) with surrounding denser vegetation, while females occupied areas of denser vegetation. Activity patterns and hunting behaviour varied between different cheetah social groups with female cheetah being more active during day light hours compared to males which made 38% of their kills after dark. The average chase distances for the various cheetah groups varied considerably, and the chase distance for successful hunts was longer than for unsuccessful for all groups except single female cheetah. The percentage of kills’ kleptoparasitised on Kwandwe was very low compared to other studies possibly due to the low density of direct competitors, which in turn lead to longer mean kill retention times. These results suggest that cheetah are more adaptable than previously thought and this adaptability may have important implications for their conservation.
  • Full Text:
  • Date Issued: 2005

Gold mineralization in a high grade metamorphic terrane in the Handeni District, Eastern Tanzania

  • Authors: Bitesigirwe, Godfrey Stephen
  • Date: 2014
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/54756 , vital:26609
  • Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
  • Full Text:
  • Date Issued: 2014

Studies on flax/polypropylene-reinforced composites for automotive applications

  • Authors: Biyana, Nobuhle Yvonne
  • Date: 2015
  • Subjects: Polypropylene fibers , Fibrous composites , Reinforced plastics
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10456 , http://hdl.handle.net/10948/d1021150
  • Description: The use of natural fibers as reinforcement in thermoplastics presents an interesting alternative for the production of low cost and ecologically friendly composites. One of the advantages of using natural fibres is their low specific weight, resulting in higher specific strength and stiffness when compared to glass reinforced composites. Natural fibres also present safer handling and working conditions. They are non-abrasive to mixing and can contribute to significant cost reduction. This work is divided into two phases: Phase 1 deals with developing nonwoven mats composites from flax/polypropylene (PP) and evaluating their properties. Flax/polypropylene fibres (at different weight ratios) were processed by needle-punching technique in order to form nonwoven mats. The mats were compression-molded at a temperature of 180oC to form composite materials. The mechanical, thermal and viscoelastic properties of the composites were analyzed. Composites (untreated and silane-treated) were also subjected to varying conditions of temperature and humidity and the tensile properties of the conditioned and unconditioned composites were investigated. The mechanical properties (tensile, flexural and impact) of flax/PP composites were found to increase and reach maximum values at 30 per cent fibre loading and then decrease at higher fibre content. Thermal studies revealed that the composites were stable up to 320oC and samples containing 40 per cent flax fibres were found to exhibit greater thermal stability than neat PP. The dynamic mechanical analyses of the composites showed that the incorporation of flax in the composites resulted in an increase of the storage modulus with a maximum value exhibited by composite containing 40 per cent fibre loading. Composites containing chemically modified fibres exhibited low tensile modulus after conditioning. Phase 2 is based on the investigation of the effect of nano-calcium carbonate (CaCO3) on the properties of two types of polymer matrices: recycled PP and virgin PP. In this case, composites were prepared by melt-mixing and injection molding. The mechanical and thermal properties of the composites were characterized. The tensile modulus of the nano-CaCO3 filled PP (virgin and recycled) composites were found to increase and reach maximum at 30 per cent nano-CaCO3 loading, while the tensile strength decreased with increasing filler content. Thermal studies showed that the nano-CaCO3 filled PP samples exhibited a one-step degradation pattern and are thermally stable up to 450oC. The thermal stability of the samples was found to decrease following the addition of nano-CaCO3. SEM micrographs of the tensile fractured surfaces of composites of the nano-CaCO3 filled virgin and recycled PP revealed the presence of nano-CaCO3 agglomeration.
  • Full Text:
  • Date Issued: 2015

Ericoid mycorrhizal fungi and potential for inoculation of commercial berry species (Vaccinium corymbosium L.)

  • Authors: Bizabani, Christine
  • Date: 2011
  • Subjects: Ericaceae , Mycorrhizas , Fynbos
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4136 , http://hdl.handle.net/10962/d1016127
  • Description: Ericaceous plants are the richest growth form of the fynbos vegetation of South Africa. The fynbos is characterized by highly leached acidic soils, low mineral nutrients and climatically it is a winter rainfall and dry summer region. Ericoid mycorrhizal fungi associate with Erica species enhancing their ability to access essential nutrients for survival under unfavourable growth conditions. The aim of this study was to select local Ericaceae plant species and to isolate, identify and characterize the ericoid endophytes and assess these isolates as potential inocula for commercial berry species. Two ericaceous plants Erica cerinthoides L. and Erica demmissa Klotzsch ex Benth. were identified from the Mountain Drive area of Grahamstown, Eastern Cape. Root staining was used to confirm the mycorrhizal status of both plants. Hyphal coils typical of ericoid association were observed within the epidermal cells of the hair roots under a light microscope. The endophytes were successfully isolated in pure culture on 2% malt extract agar (MEA) and modified Fontana medium. Cultural morphology and microscopy were used for initial identification. Two slow growing isolates were selected. These isolates were further subjected to molecular identification; extracted DNA was amplified using ITS1 and ITS4 fungal primers. The rDNA gene internal transcriber spacer (ITS) was then sequenced and analyzed by comparison to sequences in the GenBank. On the basis of percentage sequence identity Lachnum Retz. species and Cadophora Lagerb. & Melin species were identified as the ericoid endophytes of E. cerinthoides and E. demmissa respectively. The optimum growth parameters of the fungal isolates were determined in 2% MEA incubated at varying temperatures and pH. It was established that both species had optimum growth at 27⁰C and pH 5. The Ericaceae species are sometimes found in metal contaminated sites were ericoid fungi have been proved to alleviate toxicity of their host. The fungal isolates were grown in increasing concentration of Cu²⁺ and Zn²⁺ in 2% MEA. The growth of Lachnum species decreased with increasing Zn²⁺ ions above 2.7 mM while Cadophora species showed a change in morphology and also decreased in growth with increased ion concentration. However there were no significant differences recorded in the growth of Cadophora and Lachnum species on increasing Cu²⁺ concentration. Lachnum and Cadophora isolates were formulated into a semi solid inoculum and inoculated onto micropropagated Vaccinni corymbosum L. plantlets of 5 different varieties. Colonization was low for all varieties, Elliott and Brightwell varieties recorded the highest colonization of 35% and 31% respectively. Lachnum species infected roots showed potential ericoid structures while the Cadophora inoculated plantlets had hyphal coils within the cortical cells typical of ericoid mycorrhizas. Inoculation significantly enhanced the shoot growth of Brightwell and Elliott varieties. The Chandler variety inoculated with Lachnum species showed improved shoot dry weight. The Bluecrop and Elliott varieties inoculated with Cadophora and Lachnum accumulated more root biomass. All inoculated Bluecrop plantlets had an improved canopy growth index. Brightwell plantlets inoculated with Lachnum species also had an enhanced canopy growth index. The growth responses were variable within varieties and between varieties. Treatments with the Cadophora and Lachnum have shown potential in the promotion of growth of the Blueberry species. The findings indicate the need to conduct trials under conditions which simulate the commercial growth conditions so as explore the optimum potential of the isolates.
  • Full Text:
  • Date Issued: 2011
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